Jens Soukup - Academia.edu (original) (raw)
Papers by Jens Soukup
Brain Research, 2004
The aim of the present study was to examine the impact of moderate and profound hyperventilation ... more The aim of the present study was to examine the impact of moderate and profound hyperventilation on regional cerebral blood flow (rCBF), oxygenation and metabolism. Twelve anesthetized pigs were subjected to moderate (mHV) and profound (pHV) hyperventilation (target arterial pO(2): 30 and 20 mmHg, respectively) for 30 min each, after baseline normoventilation (BL) for 1 h. Local cerebral extracellular fluid (ECF) concentrations of glucose, lactate, pyruvate and glutamate as well as brain tissue oxygenation (p(ti)O(2)) were monitored using microdialysis and a Licox oxygen sensor, respectively. In nine pigs, regional cerebral blood flow (rCBF) was also continuously measured via a thermal diffusion system. Both moderate and profound hyperventilation resulted in a significant decrease in rCBF (BL: 37.9+/-4.3 ml/100 g/min; mHV: 29.4+/-3.6 ml/100 g/min; pHV: 23.6+/-4.7 ml/100 g/min; p<0.05) and p(ti)O(2) (BL: 22.7+/-4.1 mmHg; mHV: 18.9+/-4.9 mmHg; pHV: 13.0+/-2.2 mmHg; p<0.05). A p(ti)O(2) decrease below the critical threshold of 10 mmHg was induced in three animals by moderate hyperventilation and in five animals by profound hyperventilation. Furthermore, significant increases in lactate (BL: 1.06+/-0.18 mmol/l; mHV: 1.36+/-0.20 mmol/l; pHV: 1.67+/-0.17 mmol/l; p<0.005), pyruvate (BL: 46.4+/-7.8 micromol/l; mHV: 58.0+/-10.3 micromol/l; pHV: 66.1+/-12.7 micromol/l; p<0.05), and lactate/glucose ratio were observed during hyperventilation. (Data are presented as mean+/-S.E.M.) Both moderate and profound hyperventilation may result in insufficient regional oxygen supply and anaerobic metabolism, even in the uninjured brain. Therefore, the use of hyperventilation cannot be considered as a safe procedure and should either be avoided or used with extreme caution.
A prospective, randomized, double-blind study was performed in 62 patients (ASA Classes I and II)... more A prospective, randomized, double-blind study was performed in 62 patients (ASA Classes I and II) treated with either 0.15 or 0.25 mg/kg cisatracurium or 0.15 mg/kg vecuronium administered as a rapid bolus. We wished to determine whether the muscle relaxants caused cutaneous, systemic, or chemical evidence of histamine release. Six minutes after induction of anes- thesia with thiopental, patients received
Krankenhaus-Hygiene + Infektionsverhütung, 2007
ABSTRACT The routine use of volatile anesthetics in intensive care medicine has been limited so f... more ABSTRACT The routine use of volatile anesthetics in intensive care medicine has been limited so far due to technical difficulties and the need for an anaesthetic machine. The new Anesthetic Conserving Device (AnaConDa®) is a modified heat and moisture exchanger which includes activated carbon fibres. It works as a miniaturized vapor with recirculation facilitating the use of volatile anesthetic for long-term sedation with any classical ventilator. The Anaesthetic Conserving Device (AnaConDa®-System) replaces the common heat and moisture exchanger in the ventilator circuit. The volatile anaesthetic is continuously applied in liquid status via a syringe pump to the minivapor where the anesthetic is vaporized. The expired anaesthetic gas is stored in the carbon filter and about 90% are resupplied into the breathing circle. Beside the active central hospital scavenging system actual three passive scavenging systems with different modified activated charcoal can be used for anaesthesia gas scavenging from the ventilator. Current studies have experienced a safe application route, no development of tolerance as well as short wake-up times after long-term sedation with volatile anaesthetics. There is still need for studies on economical aspects. The current experiences suggest that volatile anaesthetics present an alternative for long-term sedation on intensive care units, providing optimized pathways from a medical as well as from an economical viewpoint. According to current drug-approval-laws the use of volatile anaesthetics for a longer period is an off-label use and should only be applied by medical professionals at their own responsibility.
Intensiv- und Notfallbehandlung, 2007
Der Anaesthesist
The use of volatile anaesthetics in intensive care medicine has so far been limited by the lack o... more The use of volatile anaesthetics in intensive care medicine has so far been limited by the lack of equipment suitable for daily routine use and the need for an anaesthetic machine. The new Anaesthetic Conserving Device (AnaConDa) enables the routine use of volatile anaesthetics for long-term sedation via intensive care ventilators. The Anaesthetic Conserving Device replaces the common heat and moisture exchanger in the ventilation circuit. The volatile anaesthetic is continuously applied in liquid status via a syringe pump to a form of mini-vaporiser where the anaesthetic agent is vaporised. The expired anaesthetic gas is stored in the carbon filter and approximately 90% of the gas is resupplied into the breathing cycle. The current experiences suggest that volatile anaesthetics present an alternative for long-term sedation in intensive care units, providing optimised pathways, from a medical as well as from an economical point of view. It must, however, be emphasized that the use o...
Clinical hemorheology and microcirculation, 2006
Using a well defined pig model, we investigated whether cerebral hypertension and hypotension inf... more Using a well defined pig model, we investigated whether cerebral hypertension and hypotension influence hemorheological factors. After surgical preparation and stabilization, periods of hyperventilation, controlled periods of cerebral perfusion pressure increases and decreases were utilized. After each period, blood samples were collected from the cannulated femoral artery and vein, and from the superior sagittal sinus. Erythrocyte deformability, whole blood and plasma viscosity and hematological parameters were determined. Erythrocyte deformability significantly worsened in arterial samples after hypertension and hypotension, and in sinus samples it was impaired after hypotension period. Hematocrit significantly increased in arterial and sinus samples during hypertensive period, accompanied by similar alterations in whole blood viscosity. We conclude that hemodynamic changes caused by hyperventilation, hyper- or hypotension can influence hemorheological factors, and suggest that th...
![Research paper thumbnail of Efficiency of 7.2% hypertonic saline hydroxyethyl starch 200/0.5 versus mannitol 15% in the treatment of increased intracranial pressure in neurosurgical patients - a randomized clinical trial [ISRCTN62699180]](https://attachments.academia-assets.com/42486649/thumbnails/1.jpg)
](Critical care (London, England), Jan 5, 2005
This prospective randomized clinical study investigated the efficacy and safety of 7.2% hypertoni... more This prospective randomized clinical study investigated the efficacy and safety of 7.2% hypertonic saline hydroxyethyl starch 200/0.5 (7.2% NaCl/HES 200/0.5) in comparison with 15% mannitol in the treatment of increased intracranial pressure (ICP). Forty neurosurgical patients at risk of increased ICP were randomized to receive either 7.2% NaCl/HES 200/0.5 or 15% mannitol at a defined infusion rate, which was stopped when ICP was < 15 mmHg. Of the 40 patients, 17 patients received 7.2% NaCl/HES 200/0.5 and 15 received mannitol 15%. In eight patients, ICP did not exceed 20 mmHg so treatment was not necessary. Both drugs decreased ICP below 15 mmHg (p < 0.0001); 7.2% NaCl/HES 200/0.5 within 6.0 (1.2-15.0) min (all results are presented as median (minimum-maximum range)) and mannitol within 8.7 (4.2-19.9) min (p < 0.0002). 7.2% NaCl/HES 200/0.5 caused a greater decrease in ICP than mannitol (57% vs 48%; p < 0.01). The cerebral perfusion pressure was increased from 60 (39-78...
International journal of dermatology, 2004
References 1 Dereure O. Drug induced skin pigmentation epidemiology, diagnosis and treatment. Am.... more References 1 Dereure O. Drug induced skin pigmentation epidemiology, diagnosis and treatment. Am. J. Clin Dermatol 2001; 2 : 253 -62 2 Granstein RD, Sober AJ. Drug and heavy metal induced hyperpigmentation. J Am Acad Dermatol 1981; 5 : 1 -15. 3 Rappersberger K, Honigsmann H. Ortel B, et al. Photosensitivity and hyperpigmentation in amiodarone treated patients incidence, time course and recovery. J Invest Dermatol 1989; 93 : 2201 -2209. 4 Zachary CB, Slater DN, Holt DW, et al. The pathogenesis of amiodarone-induced pigmentation and photosensitivity. Br. J Dermatol 1984; 100 : 451 -456. 5 McGrac JD, Zelickson As. Skin pigmentation secondary to minocycline therapy.
![Research paper thumbnail of Safety and efficacy of analgesia-based sedation with remifentanil versus standard hypnotic-based regimens in intensive care unit patients with brain injuries: a randomised, controlled trial [ISRCTN50308308]](https://attachments.academia-assets.com/42486678/thumbnails/1.jpg)
](Critical care (London, England), 2004
This randomised, open-label, observational, multicentre, parallel group study assessed the safety... more This randomised, open-label, observational, multicentre, parallel group study assessed the safety and efficacy of analgesia-based sedation using remifentanil in the neuro-intensive care unit. Patients aged 18-80 years admitted to the intensive care unit within the previous 24 hours, with acute brain injury or after neurosurgery, intubated, expected to require mechanical ventilation for 1-5 days and requiring daily downward titration of sedation for assessment of neurological function were studied. Patients received one of two treatment regimens. Regimen one consisted of analgesia-based sedation, in which remifentanil (initial rate 9 microg kg(-1) h(-1)) was titrated before the addition of a hypnotic agent (propofol [0.5 mg kg(-1) h(-1)] during days 1-3, midazolam [0.03 mg kg(-1) h(-1)] during days 4 and 5) (n = 84). Regimen two consisted of hypnotic-based sedation: hypnotic agent (propofol days 1-3; midazolam days 4 and 5) and fentanyl (n = 37) or morphine (n = 40) according to rout...
Anaesthesist, 1996
Zusammenfassung Der perioperative Einsatz von rekombinantem Erythropoetin (rhEPO) zeigt neue Pe... more Zusammenfassung Der perioperative Einsatz von rekombinantem Erythropoetin (rhEPO) zeigt neue Perspektiven in der Behandlung der postoperativen nichtrenalen Anämie im Rahmen fremdblutsparender Maßnahmen. Anhand des vorliegenden Fallbeispiels einer 66jährigen Patientin, die der Glaubensgemeinschaft „Zeugen Jehovas“ angehört und von uns auf die anstehende Implantation einer Hüfttotalendoprothese präoperativ mit dreimal wöchentlich 5000 I.E. sc. rekombinantem Erythropoetin behandelt wurde, soll die Möglichkeit des perioperativen
Trials, 2012
Background: State of the art sedation concepts on intensive care units (ICU) favor propofol for a... more Background: State of the art sedation concepts on intensive care units (ICU) favor propofol for a time period of up to 72 h and midazolam for long-term sedation. However, intravenous sedation is associated with complications such as development of tolerance, insufficient sedation quality, gastrointestinal paralysis, and withdrawal symptoms including cognitive deficits. Therefore, we aimed to investigate whether sevoflurane as a volatile anesthetic technically implemented by the anesthetic-conserving device (ACD) may provide advantages regarding 'weaning time', efficiency, and patient's safety when compared to standard intravenous sedation employing propofol. Method/Design: This currently ongoing trial is designed as a two-armed, monocentric, randomized prospective phase II study including intubated intensive care patients with an expected necessity for sedation exceeding 48 h. Patients are randomly assigned to either receive intravenous sedation with propofol or sevoflurane employing the ACD. Primary endpoint is the comparison of the 'weaning time' defined as the time required from discontinuation of the sedating agent until sufficient spontaneous breathing occurs. Moreover, sedation depth evaluated by Richmond Agitation Sedation Scale and parameters of patient's safety (that is, vital signs, laboratory monitoring of organ function) as well as the duration of mechanical ventilation and overall stay on the ICU are analyzed and compared. An intention-to-treat analysis will be carried out with all patients for whom it will be possible to define a wake-up time. In addition, a per-protocol analysis is envisaged. Completion of patient recruitment is expected by the end of 2012.
Journal of Pain and Symptom Management, 2003
Neuropathic pain is a major problem in the treatment of cancer pain. We performed a retrospective... more Neuropathic pain is a major problem in the treatment of cancer pain. We performed a retrospective analysis of 213 cancer patients with neuropathic pain treated by a pain service following the World Health Organization guidelines for relief of cancer pain. Of these, 79% presented with nerve compression pain, 16% with nerve injury pain, and 5% with sympathetically-maintained pain. Whereas nerve compression and nerve injury pain were caused most frequently by cancer growth, sympathetically-maintained pain was caused most frequently by cancer treatment. There were no significant differences in the use of analgesics, the mean pain intensity, or the efficacy of analgesic treatment among the three groups. Nerve injury pain and sympathetically-maintained pain were treated more frequently with adjuvant analgesics, especially antidepressants and anticonvulsants. The variety of different neuropathic pain syndromes should be separated in future studies of the efficacy of different treatment approaches.
Journal of Neurotrauma, 2002
Brain temperature was continuously measured in 58 patients after severe head injury and compared ... more Brain temperature was continuously measured in 58 patients after severe head injury and compared to rectal temperature, intracranial pressure, cerebral blood flow, and outcome after 3 months. The temperature difference between brain and rectal temperature was also calculated. Mild hypothermia (34-36 degrees C) was also used to treat uncontrollable intracranial pressure (ICP) above 20 mm Hg when other methods failed. Brain and rectal temperature were strongly correlated (r = 0.866; p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Four groups were identified. The mean brain temperature ranged from 36.9 +/- 0.4 degrees C in the normothermic group to 38.2 +/- 0.5 degrees C in the hyperthermic group, 35.3 +/- 0.5 degrees C in the mild therapeutic hypothermia group, and 34.3 +/- 1.5 degrees C in the hypothermia group without active cooling. The mean DeltaT(br-rect) was positive for patients with a T(br) above 36.0 degrees C (0.0 +/- 0.5 degrees C) and negative for patients during mild therapeutic hypothermia (-0.2 +/- 0.6 degrees C) and also in those with a brain temperature below 36 degrees C without active cooling (0.8 +/- -1.4 degrees C) - the spontaneous hypothermic group. The cerebral perfusion pressure (CPP) was increased significantly by active cooling compared to the normothermic and hyperthermic groups. The mean cerebral blood flow (CBF) in patients with a brain temperature between 36.0 degrees C and 37.5 degrees C was 37.8 +/- 14.0 mL/100 g/min. The lowest CBF was measured in patients with a brain temperature &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;36.0 degrees C and a negative brain-rectal temperature difference (17.1 +/- 14.0 mL/100 g/min). A positive trend for improved outcome was seen in patients with mild hypothermia. Simultaneous monitoring of brain and rectal temperature provides important diagnostic and prognostic information to guide the treatment of patients after severe head injury (SHI) and the wide differentials that can develop between the brain and core temperature, especially during rapid cooling, strongly supports the use of brain temperature measurement if therapeutic hypothermia is considered for head injury care.
Journal of Neurotrauma, 1998
Local brain tissue oxygenation (p(ti)O2) and global cerebrovenous hemoglobin saturation (SjO2) ar... more Local brain tissue oxygenation (p(ti)O2) and global cerebrovenous hemoglobin saturation (SjO2) are increasingly used to continuously monitor patients after severe head injury (SHI). In patients, simultaneous local and global oxygen measurements of these types have shown different results regarding the comparability of the findings during changes in CPP and ICP. This is in contrast to theoretical expectations. The aim of this study was to compare p(ti)O2 measurement with cerebrovenous oxygen partial pressure measurement (p(cv)O2) in an animal intracranial pressure model. To this end, a multisensor probe was placed in the left frontoparietal white matter to measure p(ti)O2, pCO2 (p(ti)CO2), pH (pH[ti]), and temperature (t[ti]) while simultaneously measuring these same parameters (p(cv)O2, p(cv)CO2 pH(cv), t[cv]) in the sagittal sinus of 9 pigs under general anesthesia. By stepwise inflating a balloon catheter, placed in supracerebellar infratentorial compartment, ICP was increased and CPP was decreased. The baseline levels of p(ti)O2, p(ti)CO2, and pH(ti) in the noninjured brain tissue showed more heterogeneity compared to the findings in cerebrovenous blood. Both, p(ti)O2 and p(cv)O2 were significantly correlated to the induced CPP decrease. PCO2 was inversely correlated to the course of CPP in both measurement compartments. Temperature measurement showed a positive correlation with CPP in both compartments. These findings demonstrate that brain tissue oximetry and cerebrovenous PO2 measurement are sensitive to CPP changes. The newly available continuous parameters in multisensor probes could be helpful in interpreting findings of cerebral oxygen measurement in man by analyzing the interrelationship of these parameters.
Journal of Neurosurgical Anesthesiology, 1999
Journal of Neurosurgical Anesthesiology, 2000
The objective of the first part of this study was to use an animal model to investigate the relat... more The objective of the first part of this study was to use an animal model to investigate the relationship between temperature in the cerebrovenous compartment and cerebral perfusion pressure. In the second part of the study, the objective was to examine the influence of hyperventilation and hypothermia on jugular bulb temperature and body temperature in patients undergoing elective neurosurgery. Intracranial pressure was increased artificially by inflating an infratentorial supracerebellar placed balloon catheter in nine pigs under general anesthesia. Temperature was monitored by thermocouples inserted in the sagittal sinus, white matter of the left lobe and abdominal aorta during the ensuing decrease in cerebral profusion pressure (CPP). Cerebrovenous blood temperature (jugular bulb) and body temperature (urinary bladder) were simultaneously monitored in 24 patients undergoing craniotomy. Moderate hyperventilation was performed in all patients. Cerebrovenous blood and core body temperature were recorded and differences between these two temperatures calculated at the beginning and the end of hyperventilation. At the beginning of the intracranial pressure (ICP), increase mean temperatures of cerebrovenous blood and cerebral tissue (left lobe) were lower than core body temperature. During CPP reduction the difference between core body temperature and cerebrovenous blood temperature increased significantly from 0.86+/-0.44 degrees C prior to ICP rise to 1.19+/-0.58 degrees C at maximum ICP. Before hyperventilation, cerebrovenous blood temperature was higher in 19 patients (+/- difference: 0.34 degrees C +/- 0.27) and equal or lower in five patients (difference: -0.08 degrees C +/- 0.11), than core body temperature. At the end of hyperventilation, the difference between cerebrovenous blood temperature and core body temperature increased (+0.42 degrees C +/- 0.24) in those 19 patients who had started with a higher cerebrovenous blood temperature and decreased (-0.10 degrees C +/- 0. 18) in the other five patients. Both studies demonstrated that the temperature of cerebrovenous blood is influenced by maneuvers which are supposed to decrease cerebral blood flow.
Journal of Neurosurgical Anesthesiology, 1999
Early impaired cerebral blood flow (CBF) after severe head injury (SHI) leads to poor brain tissu... more Early impaired cerebral blood flow (CBF) after severe head injury (SHI) leads to poor brain tissue oxygen delivery and lactate accumulation. The purpose of this investigation was to elucidate the relationship between CBF, local dialysate lactate (lact(md)) and dialysate glucose (gluc(md)), and brain tissue oxygen levels (PtiO2) under arterial normoxia. The effect of increased brain tissue oxygenation due to high fractions of inspired oxygen (FiO2) on lact(md) and CBF was explored. A total of 47 patients with SHI were enrolled in this studies (Glasgow Coma Score [GCS] &amp;lt; 8). CBF was first assessed in 40 patients at one time point in the first 96 hours (27 +/- 28 hours) after SHI using stable xenon computed tomography (Xe-CT) (30% inspired xenon [FiXe] and 35% FiO2). In a second study, sequential double CBF measurements were performed in 7 patients with 35% FiO2 and 60% FiO2, respectively, with an interval of 30 minutes. In a subsequent study, 14 patients underwent normobaric hyperoxia by increasing FiO2 from 35 +/- 5% to 60% and then 100% over a period of 6 hours. This was done to test the effect of normobaric hyperoxia on lact(md) and brain gluc(md), as measured by local microdialysis. Changes in PtiO2 in response to changes in FiO2 were analyzed by calculating the oxygen reactivity. Oxygen reactivity was then related to the 3-month outcome data. The levels of lact(md) and gluc(md) under hyperoxia were compared with the baseline levels, measured at 35% FiO2. Under normoxic conditions, there was a significant correlation between CBF and PtiO2 (R = 0.7; P &amp;lt; .001). In the sequential double CBF study, however, FiO2 was inversely correlated with CBF (P &amp;lt; .05). In the 14 patients undergoing the 6-hour 100% FiO2 challenge, the mean PtiO2 levels increased to 353 (87% compared with baseline), although the mean lact(md) levels decreased by 38 +/- 16% (P &amp;lt; .05). The PtiO2 response to 100% FiO2 (oxygen reactivity) was inversely correlated with outcome (P &amp;lt; .01). Monitoring PtiO2 after SHI provides valuable information about cerebral oxygenation and substrate delivery. Increasing arterial oxygen tension (PaO2) effectively increased PtiO2, and brain lact(md) was reduced by the same maneuver.
Journal of Neurosurgical Anesthesiology, 2008
Mild hyperventilation remains a key element in the management of elevated intracranial pressure. ... more Mild hyperventilation remains a key element in the management of elevated intracranial pressure. However, a harmful effect of hyperventilation on the development or deterioration of ischemic lesions has been shown in patients after severe head trauma. The objective of this study was to investigate the clinical feasibility and reliability of continuous monitoring of regional cerebral blood flow (rCBF) during mild hyperventilation using a thermodiffusion probe. CO2 reactivity was calculated. The measurement of the partial pressure of oxygen (PtiO2) in the cerebral tissue served as a reference parameter. An intraparenchymal intracranial pressure sensor, a multiparameter probe for determining the partial pressure of cerebral gases (pHti, PtiO2, PtiCO2), and a thermodiffusion probe for measuring rCBF were used in 10 intensive care patients. All patients were analgosedated and received pressure-controlled mechanical ventilation. Controlled mild hyperventilation was carried out on 2 consecutive days. CO2 reactivity was determined in relation to both CBF and PtiO2. Controlled hyperventilation resulted in a rCBF reduction from 30+/-3 mL/100 g/min to 25+/-2.4 mL/100 g/min (-17%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the first day of examination and 31+/-3.6 mL/100 g/min to 22+/-4.9 mL/100 g/min (-29%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the second day. Likewise, mild hyperventilation resulted in a reduction of regional cerebral tissue oxygen partial pressure from 20+/-2.9 mm Hg to 15+/-4 (-25%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the first day and 20+/-3.1 mm Hg to 14+/-1.5 mm Hg (-30%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the second. Continuous monitoring of regional CBF, using an intraparenchymally placed thermodiffusion probe, seems to be a simple and safe bedside technique. The promise of reliably monitoring and interpreting additional parameters such as PtiO2 and PtiCO2 warrants further investigation.
Journal of Neurosurgery, 1999
Early impairment of cerebral blood flow in patients with severe head injury correlates with poor ... more Early impairment of cerebral blood flow in patients with severe head injury correlates with poor brain tissue O2 delivery and may be an important cause of ischemic brain damage. The purpose of this study was to measure cerebral tissue PO2, lactate, and glucose in patients after severe head injury to determine the effect of increased tissue O2 achieved by increasing the fraction of inspired oxygen (FiO2). In addition to standard monitoring of intracranial pressure and cerebral perfusion pressure, the authors continuously measured brain tissue PO2, PCO2, pH, and temperature in 22 patients with severe head injury. Microdialysis was performed to analyze lactate and glucose levels. In one cohort of 12 patients, the PaO2 was increased to 441+/-88 mm Hg over a period of 6 hours by raising the FiO2 from 35+/-5% to 100% in two stages. The results were analyzed and compared with the findings in a control cohort of 12 patients who received standard respiratory therapy (mean PaO2 136.4+/-22.1 mm Hg). The mean brain PO2 levels increased in the O2-treated patients up to 359+/-39% of the baseline level during the 6-hour FiO2 enhancement period, whereas the mean dialysate lactate levels decreased by 40% (p &amp;lt; 0.05). During this O2 enhancement period, glucose levels in brain tissue demonstrated a heterogeneous course. None of the monitored parameters in the control cohort showed significant variations during the entire observation period. Markedly elevated lactate levels in brain tissue are common after severe head injury. Increasing PaO2 to higher levels than necessary to saturate hemoglobin, as performed in the O2-treated cohort, appears to improve the O2 supply in brain tissue. During the early period after severe head injury, increased lactate levels in brain tissue were reduced by increasing FiO2. This may imply a shift to aerobic metabolism.
Journal of Neurosurgery, 2005
Brain tissue acidosis is known to mediate neuronal death. Therefore the authors measured the main... more Brain tissue acidosis is known to mediate neuronal death. Therefore the authors measured the main parameters of cerebral acid-base homeostasis, as well as their interrelations, shortly after severe traumatic brain injury (TBI) in humans. Brain tissue pH, PCO2, PO2, and/or lactate were measured in 151 patients with severe head injuries, by using a Neurotrend sensor and/or a microdialysis probe. Monitoring was started as soon as possible after the injury and continued for up to 4 days. During the 1st day following the trauma, the brain tissue pH was significantly lower, compared with later time points, in patients who died or remained in a persistent vegetative state. Six hours after the injury, brain tissue PCO2 was significantly higher in patients with a poor outcome compared with patients with a good outcome. Furthermore, significant elevations in cerebral concentrations of lactate were found during the 1st day after the injury, compared with later time points. These increases in lactate were typically more pronounced in patients with a poor outcome. Similar biochemical changes were observed during later hypoxic events. Severe human TBI profoundly disturbs cerebral acid-base homeostasis. The observed pH changes persist for the first 24 hours after the trauma. Brain tissue acidosis is associated with increased tissue PCO2 and lactate concentration; these pathobiochemical changes are more severe in patients who remain in a persistent vegetative state or die. Furthermore, increased brain tissue PCO2 (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 60 mm Hg) appears to be a useful clinical indicator of critical cerebral ischemia, especially when accompanied by increased lactate concentrations.
Brain Research, 2004
The aim of the present study was to examine the impact of moderate and profound hyperventilation ... more The aim of the present study was to examine the impact of moderate and profound hyperventilation on regional cerebral blood flow (rCBF), oxygenation and metabolism. Twelve anesthetized pigs were subjected to moderate (mHV) and profound (pHV) hyperventilation (target arterial pO(2): 30 and 20 mmHg, respectively) for 30 min each, after baseline normoventilation (BL) for 1 h. Local cerebral extracellular fluid (ECF) concentrations of glucose, lactate, pyruvate and glutamate as well as brain tissue oxygenation (p(ti)O(2)) were monitored using microdialysis and a Licox oxygen sensor, respectively. In nine pigs, regional cerebral blood flow (rCBF) was also continuously measured via a thermal diffusion system. Both moderate and profound hyperventilation resulted in a significant decrease in rCBF (BL: 37.9+/-4.3 ml/100 g/min; mHV: 29.4+/-3.6 ml/100 g/min; pHV: 23.6+/-4.7 ml/100 g/min; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) and p(ti)O(2) (BL: 22.7+/-4.1 mmHg; mHV: 18.9+/-4.9 mmHg; pHV: 13.0+/-2.2 mmHg; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). A p(ti)O(2) decrease below the critical threshold of 10 mmHg was induced in three animals by moderate hyperventilation and in five animals by profound hyperventilation. Furthermore, significant increases in lactate (BL: 1.06+/-0.18 mmol/l; mHV: 1.36+/-0.20 mmol/l; pHV: 1.67+/-0.17 mmol/l; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.005), pyruvate (BL: 46.4+/-7.8 micromol/l; mHV: 58.0+/-10.3 micromol/l; pHV: 66.1+/-12.7 micromol/l; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05), and lactate/glucose ratio were observed during hyperventilation. (Data are presented as mean+/-S.E.M.) Both moderate and profound hyperventilation may result in insufficient regional oxygen supply and anaerobic metabolism, even in the uninjured brain. Therefore, the use of hyperventilation cannot be considered as a safe procedure and should either be avoided or used with extreme caution.
A prospective, randomized, double-blind study was performed in 62 patients (ASA Classes I and II)... more A prospective, randomized, double-blind study was performed in 62 patients (ASA Classes I and II) treated with either 0.15 or 0.25 mg/kg cisatracurium or 0.15 mg/kg vecuronium administered as a rapid bolus. We wished to determine whether the muscle relaxants caused cutaneous, systemic, or chemical evidence of histamine release. Six minutes after induction of anes- thesia with thiopental, patients received
Krankenhaus-Hygiene + Infektionsverhütung, 2007
ABSTRACT The routine use of volatile anesthetics in intensive care medicine has been limited so f... more ABSTRACT The routine use of volatile anesthetics in intensive care medicine has been limited so far due to technical difficulties and the need for an anaesthetic machine. The new Anesthetic Conserving Device (AnaConDa®) is a modified heat and moisture exchanger which includes activated carbon fibres. It works as a miniaturized vapor with recirculation facilitating the use of volatile anesthetic for long-term sedation with any classical ventilator. The Anaesthetic Conserving Device (AnaConDa®-System) replaces the common heat and moisture exchanger in the ventilator circuit. The volatile anaesthetic is continuously applied in liquid status via a syringe pump to the minivapor where the anesthetic is vaporized. The expired anaesthetic gas is stored in the carbon filter and about 90% are resupplied into the breathing circle. Beside the active central hospital scavenging system actual three passive scavenging systems with different modified activated charcoal can be used for anaesthesia gas scavenging from the ventilator. Current studies have experienced a safe application route, no development of tolerance as well as short wake-up times after long-term sedation with volatile anaesthetics. There is still need for studies on economical aspects. The current experiences suggest that volatile anaesthetics present an alternative for long-term sedation on intensive care units, providing optimized pathways from a medical as well as from an economical viewpoint. According to current drug-approval-laws the use of volatile anaesthetics for a longer period is an off-label use and should only be applied by medical professionals at their own responsibility.
Intensiv- und Notfallbehandlung, 2007
Der Anaesthesist
The use of volatile anaesthetics in intensive care medicine has so far been limited by the lack o... more The use of volatile anaesthetics in intensive care medicine has so far been limited by the lack of equipment suitable for daily routine use and the need for an anaesthetic machine. The new Anaesthetic Conserving Device (AnaConDa) enables the routine use of volatile anaesthetics for long-term sedation via intensive care ventilators. The Anaesthetic Conserving Device replaces the common heat and moisture exchanger in the ventilation circuit. The volatile anaesthetic is continuously applied in liquid status via a syringe pump to a form of mini-vaporiser where the anaesthetic agent is vaporised. The expired anaesthetic gas is stored in the carbon filter and approximately 90% of the gas is resupplied into the breathing cycle. The current experiences suggest that volatile anaesthetics present an alternative for long-term sedation in intensive care units, providing optimised pathways, from a medical as well as from an economical point of view. It must, however, be emphasized that the use o...
Clinical hemorheology and microcirculation, 2006
Using a well defined pig model, we investigated whether cerebral hypertension and hypotension inf... more Using a well defined pig model, we investigated whether cerebral hypertension and hypotension influence hemorheological factors. After surgical preparation and stabilization, periods of hyperventilation, controlled periods of cerebral perfusion pressure increases and decreases were utilized. After each period, blood samples were collected from the cannulated femoral artery and vein, and from the superior sagittal sinus. Erythrocyte deformability, whole blood and plasma viscosity and hematological parameters were determined. Erythrocyte deformability significantly worsened in arterial samples after hypertension and hypotension, and in sinus samples it was impaired after hypotension period. Hematocrit significantly increased in arterial and sinus samples during hypertensive period, accompanied by similar alterations in whole blood viscosity. We conclude that hemodynamic changes caused by hyperventilation, hyper- or hypotension can influence hemorheological factors, and suggest that th...
Critical care (London, England), Jan 5, 2005
This prospective randomized clinical study investigated the efficacy and safety of 7.2% hypertoni... more This prospective randomized clinical study investigated the efficacy and safety of 7.2% hypertonic saline hydroxyethyl starch 200/0.5 (7.2% NaCl/HES 200/0.5) in comparison with 15% mannitol in the treatment of increased intracranial pressure (ICP). Forty neurosurgical patients at risk of increased ICP were randomized to receive either 7.2% NaCl/HES 200/0.5 or 15% mannitol at a defined infusion rate, which was stopped when ICP was < 15 mmHg. Of the 40 patients, 17 patients received 7.2% NaCl/HES 200/0.5 and 15 received mannitol 15%. In eight patients, ICP did not exceed 20 mmHg so treatment was not necessary. Both drugs decreased ICP below 15 mmHg (p < 0.0001); 7.2% NaCl/HES 200/0.5 within 6.0 (1.2-15.0) min (all results are presented as median (minimum-maximum range)) and mannitol within 8.7 (4.2-19.9) min (p < 0.0002). 7.2% NaCl/HES 200/0.5 caused a greater decrease in ICP than mannitol (57% vs 48%; p < 0.01). The cerebral perfusion pressure was increased from 60 (39-78...
International journal of dermatology, 2004
References 1 Dereure O. Drug induced skin pigmentation epidemiology, diagnosis and treatment. Am.... more References 1 Dereure O. Drug induced skin pigmentation epidemiology, diagnosis and treatment. Am. J. Clin Dermatol 2001; 2 : 253 -62 2 Granstein RD, Sober AJ. Drug and heavy metal induced hyperpigmentation. J Am Acad Dermatol 1981; 5 : 1 -15. 3 Rappersberger K, Honigsmann H. Ortel B, et al. Photosensitivity and hyperpigmentation in amiodarone treated patients incidence, time course and recovery. J Invest Dermatol 1989; 93 : 2201 -2209. 4 Zachary CB, Slater DN, Holt DW, et al. The pathogenesis of amiodarone-induced pigmentation and photosensitivity. Br. J Dermatol 1984; 100 : 451 -456. 5 McGrac JD, Zelickson As. Skin pigmentation secondary to minocycline therapy.
Critical care (London, England), 2004
This randomised, open-label, observational, multicentre, parallel group study assessed the safety... more This randomised, open-label, observational, multicentre, parallel group study assessed the safety and efficacy of analgesia-based sedation using remifentanil in the neuro-intensive care unit. Patients aged 18-80 years admitted to the intensive care unit within the previous 24 hours, with acute brain injury or after neurosurgery, intubated, expected to require mechanical ventilation for 1-5 days and requiring daily downward titration of sedation for assessment of neurological function were studied. Patients received one of two treatment regimens. Regimen one consisted of analgesia-based sedation, in which remifentanil (initial rate 9 microg kg(-1) h(-1)) was titrated before the addition of a hypnotic agent (propofol [0.5 mg kg(-1) h(-1)] during days 1-3, midazolam [0.03 mg kg(-1) h(-1)] during days 4 and 5) (n = 84). Regimen two consisted of hypnotic-based sedation: hypnotic agent (propofol days 1-3; midazolam days 4 and 5) and fentanyl (n = 37) or morphine (n = 40) according to rout...
Anaesthesist, 1996
Zusammenfassung Der perioperative Einsatz von rekombinantem Erythropoetin (rhEPO) zeigt neue Pe... more Zusammenfassung Der perioperative Einsatz von rekombinantem Erythropoetin (rhEPO) zeigt neue Perspektiven in der Behandlung der postoperativen nichtrenalen Anämie im Rahmen fremdblutsparender Maßnahmen. Anhand des vorliegenden Fallbeispiels einer 66jährigen Patientin, die der Glaubensgemeinschaft „Zeugen Jehovas“ angehört und von uns auf die anstehende Implantation einer Hüfttotalendoprothese präoperativ mit dreimal wöchentlich 5000 I.E. sc. rekombinantem Erythropoetin behandelt wurde, soll die Möglichkeit des perioperativen
Trials, 2012
Background: State of the art sedation concepts on intensive care units (ICU) favor propofol for a... more Background: State of the art sedation concepts on intensive care units (ICU) favor propofol for a time period of up to 72 h and midazolam for long-term sedation. However, intravenous sedation is associated with complications such as development of tolerance, insufficient sedation quality, gastrointestinal paralysis, and withdrawal symptoms including cognitive deficits. Therefore, we aimed to investigate whether sevoflurane as a volatile anesthetic technically implemented by the anesthetic-conserving device (ACD) may provide advantages regarding 'weaning time', efficiency, and patient's safety when compared to standard intravenous sedation employing propofol. Method/Design: This currently ongoing trial is designed as a two-armed, monocentric, randomized prospective phase II study including intubated intensive care patients with an expected necessity for sedation exceeding 48 h. Patients are randomly assigned to either receive intravenous sedation with propofol or sevoflurane employing the ACD. Primary endpoint is the comparison of the 'weaning time' defined as the time required from discontinuation of the sedating agent until sufficient spontaneous breathing occurs. Moreover, sedation depth evaluated by Richmond Agitation Sedation Scale and parameters of patient's safety (that is, vital signs, laboratory monitoring of organ function) as well as the duration of mechanical ventilation and overall stay on the ICU are analyzed and compared. An intention-to-treat analysis will be carried out with all patients for whom it will be possible to define a wake-up time. In addition, a per-protocol analysis is envisaged. Completion of patient recruitment is expected by the end of 2012.
Journal of Pain and Symptom Management, 2003
Neuropathic pain is a major problem in the treatment of cancer pain. We performed a retrospective... more Neuropathic pain is a major problem in the treatment of cancer pain. We performed a retrospective analysis of 213 cancer patients with neuropathic pain treated by a pain service following the World Health Organization guidelines for relief of cancer pain. Of these, 79% presented with nerve compression pain, 16% with nerve injury pain, and 5% with sympathetically-maintained pain. Whereas nerve compression and nerve injury pain were caused most frequently by cancer growth, sympathetically-maintained pain was caused most frequently by cancer treatment. There were no significant differences in the use of analgesics, the mean pain intensity, or the efficacy of analgesic treatment among the three groups. Nerve injury pain and sympathetically-maintained pain were treated more frequently with adjuvant analgesics, especially antidepressants and anticonvulsants. The variety of different neuropathic pain syndromes should be separated in future studies of the efficacy of different treatment approaches.
Journal of Neurotrauma, 2002
Brain temperature was continuously measured in 58 patients after severe head injury and compared ... more Brain temperature was continuously measured in 58 patients after severe head injury and compared to rectal temperature, intracranial pressure, cerebral blood flow, and outcome after 3 months. The temperature difference between brain and rectal temperature was also calculated. Mild hypothermia (34-36 degrees C) was also used to treat uncontrollable intracranial pressure (ICP) above 20 mm Hg when other methods failed. Brain and rectal temperature were strongly correlated (r = 0.866; p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Four groups were identified. The mean brain temperature ranged from 36.9 +/- 0.4 degrees C in the normothermic group to 38.2 +/- 0.5 degrees C in the hyperthermic group, 35.3 +/- 0.5 degrees C in the mild therapeutic hypothermia group, and 34.3 +/- 1.5 degrees C in the hypothermia group without active cooling. The mean DeltaT(br-rect) was positive for patients with a T(br) above 36.0 degrees C (0.0 +/- 0.5 degrees C) and negative for patients during mild therapeutic hypothermia (-0.2 +/- 0.6 degrees C) and also in those with a brain temperature below 36 degrees C without active cooling (0.8 +/- -1.4 degrees C) - the spontaneous hypothermic group. The cerebral perfusion pressure (CPP) was increased significantly by active cooling compared to the normothermic and hyperthermic groups. The mean cerebral blood flow (CBF) in patients with a brain temperature between 36.0 degrees C and 37.5 degrees C was 37.8 +/- 14.0 mL/100 g/min. The lowest CBF was measured in patients with a brain temperature &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;36.0 degrees C and a negative brain-rectal temperature difference (17.1 +/- 14.0 mL/100 g/min). A positive trend for improved outcome was seen in patients with mild hypothermia. Simultaneous monitoring of brain and rectal temperature provides important diagnostic and prognostic information to guide the treatment of patients after severe head injury (SHI) and the wide differentials that can develop between the brain and core temperature, especially during rapid cooling, strongly supports the use of brain temperature measurement if therapeutic hypothermia is considered for head injury care.
Journal of Neurotrauma, 1998
Local brain tissue oxygenation (p(ti)O2) and global cerebrovenous hemoglobin saturation (SjO2) ar... more Local brain tissue oxygenation (p(ti)O2) and global cerebrovenous hemoglobin saturation (SjO2) are increasingly used to continuously monitor patients after severe head injury (SHI). In patients, simultaneous local and global oxygen measurements of these types have shown different results regarding the comparability of the findings during changes in CPP and ICP. This is in contrast to theoretical expectations. The aim of this study was to compare p(ti)O2 measurement with cerebrovenous oxygen partial pressure measurement (p(cv)O2) in an animal intracranial pressure model. To this end, a multisensor probe was placed in the left frontoparietal white matter to measure p(ti)O2, pCO2 (p(ti)CO2), pH (pH[ti]), and temperature (t[ti]) while simultaneously measuring these same parameters (p(cv)O2, p(cv)CO2 pH(cv), t[cv]) in the sagittal sinus of 9 pigs under general anesthesia. By stepwise inflating a balloon catheter, placed in supracerebellar infratentorial compartment, ICP was increased and CPP was decreased. The baseline levels of p(ti)O2, p(ti)CO2, and pH(ti) in the noninjured brain tissue showed more heterogeneity compared to the findings in cerebrovenous blood. Both, p(ti)O2 and p(cv)O2 were significantly correlated to the induced CPP decrease. PCO2 was inversely correlated to the course of CPP in both measurement compartments. Temperature measurement showed a positive correlation with CPP in both compartments. These findings demonstrate that brain tissue oximetry and cerebrovenous PO2 measurement are sensitive to CPP changes. The newly available continuous parameters in multisensor probes could be helpful in interpreting findings of cerebral oxygen measurement in man by analyzing the interrelationship of these parameters.
Journal of Neurosurgical Anesthesiology, 1999
Journal of Neurosurgical Anesthesiology, 2000
The objective of the first part of this study was to use an animal model to investigate the relat... more The objective of the first part of this study was to use an animal model to investigate the relationship between temperature in the cerebrovenous compartment and cerebral perfusion pressure. In the second part of the study, the objective was to examine the influence of hyperventilation and hypothermia on jugular bulb temperature and body temperature in patients undergoing elective neurosurgery. Intracranial pressure was increased artificially by inflating an infratentorial supracerebellar placed balloon catheter in nine pigs under general anesthesia. Temperature was monitored by thermocouples inserted in the sagittal sinus, white matter of the left lobe and abdominal aorta during the ensuing decrease in cerebral profusion pressure (CPP). Cerebrovenous blood temperature (jugular bulb) and body temperature (urinary bladder) were simultaneously monitored in 24 patients undergoing craniotomy. Moderate hyperventilation was performed in all patients. Cerebrovenous blood and core body temperature were recorded and differences between these two temperatures calculated at the beginning and the end of hyperventilation. At the beginning of the intracranial pressure (ICP), increase mean temperatures of cerebrovenous blood and cerebral tissue (left lobe) were lower than core body temperature. During CPP reduction the difference between core body temperature and cerebrovenous blood temperature increased significantly from 0.86+/-0.44 degrees C prior to ICP rise to 1.19+/-0.58 degrees C at maximum ICP. Before hyperventilation, cerebrovenous blood temperature was higher in 19 patients (+/- difference: 0.34 degrees C +/- 0.27) and equal or lower in five patients (difference: -0.08 degrees C +/- 0.11), than core body temperature. At the end of hyperventilation, the difference between cerebrovenous blood temperature and core body temperature increased (+0.42 degrees C +/- 0.24) in those 19 patients who had started with a higher cerebrovenous blood temperature and decreased (-0.10 degrees C +/- 0. 18) in the other five patients. Both studies demonstrated that the temperature of cerebrovenous blood is influenced by maneuvers which are supposed to decrease cerebral blood flow.
Journal of Neurosurgical Anesthesiology, 1999
Early impaired cerebral blood flow (CBF) after severe head injury (SHI) leads to poor brain tissu... more Early impaired cerebral blood flow (CBF) after severe head injury (SHI) leads to poor brain tissue oxygen delivery and lactate accumulation. The purpose of this investigation was to elucidate the relationship between CBF, local dialysate lactate (lact(md)) and dialysate glucose (gluc(md)), and brain tissue oxygen levels (PtiO2) under arterial normoxia. The effect of increased brain tissue oxygenation due to high fractions of inspired oxygen (FiO2) on lact(md) and CBF was explored. A total of 47 patients with SHI were enrolled in this studies (Glasgow Coma Score [GCS] &amp;lt; 8). CBF was first assessed in 40 patients at one time point in the first 96 hours (27 +/- 28 hours) after SHI using stable xenon computed tomography (Xe-CT) (30% inspired xenon [FiXe] and 35% FiO2). In a second study, sequential double CBF measurements were performed in 7 patients with 35% FiO2 and 60% FiO2, respectively, with an interval of 30 minutes. In a subsequent study, 14 patients underwent normobaric hyperoxia by increasing FiO2 from 35 +/- 5% to 60% and then 100% over a period of 6 hours. This was done to test the effect of normobaric hyperoxia on lact(md) and brain gluc(md), as measured by local microdialysis. Changes in PtiO2 in response to changes in FiO2 were analyzed by calculating the oxygen reactivity. Oxygen reactivity was then related to the 3-month outcome data. The levels of lact(md) and gluc(md) under hyperoxia were compared with the baseline levels, measured at 35% FiO2. Under normoxic conditions, there was a significant correlation between CBF and PtiO2 (R = 0.7; P &amp;lt; .001). In the sequential double CBF study, however, FiO2 was inversely correlated with CBF (P &amp;lt; .05). In the 14 patients undergoing the 6-hour 100% FiO2 challenge, the mean PtiO2 levels increased to 353 (87% compared with baseline), although the mean lact(md) levels decreased by 38 +/- 16% (P &amp;lt; .05). The PtiO2 response to 100% FiO2 (oxygen reactivity) was inversely correlated with outcome (P &amp;lt; .01). Monitoring PtiO2 after SHI provides valuable information about cerebral oxygenation and substrate delivery. Increasing arterial oxygen tension (PaO2) effectively increased PtiO2, and brain lact(md) was reduced by the same maneuver.
Journal of Neurosurgical Anesthesiology, 2008
Mild hyperventilation remains a key element in the management of elevated intracranial pressure. ... more Mild hyperventilation remains a key element in the management of elevated intracranial pressure. However, a harmful effect of hyperventilation on the development or deterioration of ischemic lesions has been shown in patients after severe head trauma. The objective of this study was to investigate the clinical feasibility and reliability of continuous monitoring of regional cerebral blood flow (rCBF) during mild hyperventilation using a thermodiffusion probe. CO2 reactivity was calculated. The measurement of the partial pressure of oxygen (PtiO2) in the cerebral tissue served as a reference parameter. An intraparenchymal intracranial pressure sensor, a multiparameter probe for determining the partial pressure of cerebral gases (pHti, PtiO2, PtiCO2), and a thermodiffusion probe for measuring rCBF were used in 10 intensive care patients. All patients were analgosedated and received pressure-controlled mechanical ventilation. Controlled mild hyperventilation was carried out on 2 consecutive days. CO2 reactivity was determined in relation to both CBF and PtiO2. Controlled hyperventilation resulted in a rCBF reduction from 30+/-3 mL/100 g/min to 25+/-2.4 mL/100 g/min (-17%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the first day of examination and 31+/-3.6 mL/100 g/min to 22+/-4.9 mL/100 g/min (-29%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the second day. Likewise, mild hyperventilation resulted in a reduction of regional cerebral tissue oxygen partial pressure from 20+/-2.9 mm Hg to 15+/-4 (-25%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the first day and 20+/-3.1 mm Hg to 14+/-1.5 mm Hg (-30%; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) on the second. Continuous monitoring of regional CBF, using an intraparenchymally placed thermodiffusion probe, seems to be a simple and safe bedside technique. The promise of reliably monitoring and interpreting additional parameters such as PtiO2 and PtiCO2 warrants further investigation.
Journal of Neurosurgery, 1999
Early impairment of cerebral blood flow in patients with severe head injury correlates with poor ... more Early impairment of cerebral blood flow in patients with severe head injury correlates with poor brain tissue O2 delivery and may be an important cause of ischemic brain damage. The purpose of this study was to measure cerebral tissue PO2, lactate, and glucose in patients after severe head injury to determine the effect of increased tissue O2 achieved by increasing the fraction of inspired oxygen (FiO2). In addition to standard monitoring of intracranial pressure and cerebral perfusion pressure, the authors continuously measured brain tissue PO2, PCO2, pH, and temperature in 22 patients with severe head injury. Microdialysis was performed to analyze lactate and glucose levels. In one cohort of 12 patients, the PaO2 was increased to 441+/-88 mm Hg over a period of 6 hours by raising the FiO2 from 35+/-5% to 100% in two stages. The results were analyzed and compared with the findings in a control cohort of 12 patients who received standard respiratory therapy (mean PaO2 136.4+/-22.1 mm Hg). The mean brain PO2 levels increased in the O2-treated patients up to 359+/-39% of the baseline level during the 6-hour FiO2 enhancement period, whereas the mean dialysate lactate levels decreased by 40% (p &amp;lt; 0.05). During this O2 enhancement period, glucose levels in brain tissue demonstrated a heterogeneous course. None of the monitored parameters in the control cohort showed significant variations during the entire observation period. Markedly elevated lactate levels in brain tissue are common after severe head injury. Increasing PaO2 to higher levels than necessary to saturate hemoglobin, as performed in the O2-treated cohort, appears to improve the O2 supply in brain tissue. During the early period after severe head injury, increased lactate levels in brain tissue were reduced by increasing FiO2. This may imply a shift to aerobic metabolism.
Journal of Neurosurgery, 2005
Brain tissue acidosis is known to mediate neuronal death. Therefore the authors measured the main... more Brain tissue acidosis is known to mediate neuronal death. Therefore the authors measured the main parameters of cerebral acid-base homeostasis, as well as their interrelations, shortly after severe traumatic brain injury (TBI) in humans. Brain tissue pH, PCO2, PO2, and/or lactate were measured in 151 patients with severe head injuries, by using a Neurotrend sensor and/or a microdialysis probe. Monitoring was started as soon as possible after the injury and continued for up to 4 days. During the 1st day following the trauma, the brain tissue pH was significantly lower, compared with later time points, in patients who died or remained in a persistent vegetative state. Six hours after the injury, brain tissue PCO2 was significantly higher in patients with a poor outcome compared with patients with a good outcome. Furthermore, significant elevations in cerebral concentrations of lactate were found during the 1st day after the injury, compared with later time points. These increases in lactate were typically more pronounced in patients with a poor outcome. Similar biochemical changes were observed during later hypoxic events. Severe human TBI profoundly disturbs cerebral acid-base homeostasis. The observed pH changes persist for the first 24 hours after the trauma. Brain tissue acidosis is associated with increased tissue PCO2 and lactate concentration; these pathobiochemical changes are more severe in patients who remain in a persistent vegetative state or die. Furthermore, increased brain tissue PCO2 (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 60 mm Hg) appears to be a useful clinical indicator of critical cerebral ischemia, especially when accompanied by increased lactate concentrations.