Karel Vermeyen - Academia.edu (original) (raw)
Papers by Karel Vermeyen
In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pr... more In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pressure in the paratracheal region and in the deltoid and supraspinatus muscles, looking for evidence of a potentially dangerous rise in pressure, especially in the paratracheal region. Statistical analysis was used to determine predictable variables of the time of reaching maximum pressure in and between the three regions. Deltoid pressure rose quickly during surgery, and did not drop to baseline levels at the end of surgery. Supraspinatus pressures showed a similar trend but with lower maximum levels of pressure rise. Five patients had an (unexpected) rise in paratracheal pressure, with an absolute maximum of 133.4 mmHg in one. In only two patients, did "10 minutes post-op" paratracheal pressure levels not drop to baseline levels. No respiratory problems occurred during any procedure. There are no variables to predict a potentially dangerous rise in surrounding soft tissue pre...
Acta Orthopaedica Belgica, Nov 1, 2005
In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pr... more In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pressure in the paratracheal region and in the deltoid and supraspinatus muscles, looking for evidence of a potentially dangerous rise in pressure, especially in the paratracheal region. Statistical analysis was used to determine predictable variables of the time of reaching maximum pressure in and between the three regions. Deltoid pressure rose quickly during surgery, and did not drop to baseline levels at the end of surgery. Supraspinatus pressures showed a similar trend but with lower maximum levels of pressure rise. Five patients had an (unexpected) rise in paratracheal pressure, with an absolute maximum of 133.4 mmHg in one. In only two patients, did "10 minutes post-op" paratracheal pressure levels not drop to baseline levels. No respiratory problems occurred during any procedure. There are no variables to predict a potentially dangerous rise in surrounding soft tissue pressure during shoulder arthroscopy. We recommend endotracheal intubation during shoulder arthroscopy.
International Journal of Nursing Studies, 2009
Aim-To study the relationship between nurse work environment, job outcomes and nurse-assessed qua... more Aim-To study the relationship between nurse work environment, job outcomes and nurse-assessed quality of care in the Belgian context. Background-Work environment characteristics are important for attracting and retaining professional nurses in hospitals. The Revised Nursing Work Index (NWI-R) was originally designed to describe the professional nurse work environment in U.S. Magnet Hospitals and subsequently has been extensively used in research internationally. Method-The NWI-R was translated into Dutch to measure the nurse work environment in 155 nurses across 13 units in three Belgian hospitals. Factor analysis was used to identify a set of coherent subscales. The relationship between work environments and job outcomes and nurse-assessed quality of care was investigated using logistic and linear regression analyses. Results: Three reliable, consistent and meaningful subscales of the NWI-R were identified: nurse-physician relations, nurse management at the unit level and hospital management and organizational support. All three subscales had significant associations with several outcome variables. Nurse-physician relations had a significant positive association with nurse job satisfaction, intention to stay the hospital, the nurseassessed unit level quality of care and personal accomplishment. Nurse management at the unit level had a significant positive association with the nurse job satisfaction, nurse-assessed quality of care on the unit and in the hospital, and personal accomplishment. Hospital management and organizational support had a significant positive association with the nurse-assessed quality of care
Pharmacology Biochemistry and Behavior, 2003
Although exogenous opioids alter the responses of animals to tissue-damaging stimuli and therefor... more Although exogenous opioids alter the responses of animals to tissue-damaging stimuli and therefore are the cornerstone in the treatment of acute antinociception, they have profound side effects on ventilation. To diminish ventilatory effects, combination therapies have been advocated. Recent studies reported the effectiveness of the addition of N-methyl-D-aspartate (NMDA) receptor antagonists such as ketamine to morphine in the treatment of acute pain. However, NMDA receptors, together with non-NMDA receptors are known to be involved in the neurotransmission of inspiratory drive to phrenic motoneurons. Co-administration of NMDA and non-NMDA receptor antagonists has been shown to be deleterious to respiratory function. The present study investigated the hypothesis that the association of opioids and NMDA receptor antagonists may add to the impairment of respiratory parameters. In male Wistar rats, combinations of opioids (fentanyl or morphine) at antinociceptive doses and NMDA receptor antagonists (ketamine, 40 mg/kg, or dextromethorphan, 10 mg/kg) at subanesthetic doses were administered intraperitoneally. Antinociception was tested with the tail-withdrawal reaction (TWR) test, while the effect on respiratory parameters was investigated with blood-gas analysis. We found that, in rats, co-administration of NMDA receptor antagonists and opioids may result in an increased respiratory depression as compared to the opioids alone. The effect of the NMDA receptor antagonists on opioid-induced antinociception was limited.
Pediatric Anesthesia, 2004
Journal of Cardiothoracic and Vascular Anesthesia, 2001
To analyze the effects of the pericardium on the length-dependent regulation of myocardial functi... more To analyze the effects of the pericardium on the length-dependent regulation of myocardial function in coronary artery surgery patients. Prospective. University hospital. Patients scheduled for elective coronary artery surgery. In 10 patients, a combined micromanometer transducer conductance catheter was inserted into the left ventricle for measurement of left ventricular pressures and volumes. Consecutive data were obtained during a progressive increase in left ventricular pressures and volumes obtained by leg elevation in closed chest-closed pericardium and open chest-open pericardium conditions. Pericardiotomy did not alter baseline left ventricular hemodynamics. The effects of leg elevation were different, however. In closed chest-closed pericardium conditions, stroke volume and stroke work remained unchanged, whereas these parameters increased in open chest-open pericardium conditions. This increase was related to the increase in end-diastolic volume that was observed in open chest-open pericardium conditions and not in closed chest-closed pericardium conditions. In coronary artery surgery patients, pericardiotomy does not alter baseline left ventricular function. When cardiac load is increased by leg elevation, however, use of the Frank-Starling mechanism is enhanced in open chest-open pericardium conditions.
Journal of Cardiothoracic and Vascular Anesthesia, 1995
To estimate myocardial oxygen needs by studying the effects of reduced coronary blood flow on seg... more To estimate myocardial oxygen needs by studying the effects of reduced coronary blood flow on segmental myocardial function. To study the tolerance of limited oxygen supply to a myocardial segment during propofol administration. Design: A prospective experimental study. Setting: An experimental animal laboratory in a university. Participants: Eighteen adult dogs, weighing 20 to 35 kg. Interventions: Open thorax open pericardium experiments were performed under standard anesthetic conditions. Segment length gauges were placed subendocardially in an anteroapical and in a basal segment. Flow to the anteroapical segment was reduced by tightening a micrometer-controlled snare placed around the second diagonal coronary artery. Left ventricular pressure-length signals allowed for identification of onset of relaxation dysfunction. Myocardial tissue flow at onset of relaxation dysfunction was defined as critical flow. Tracer microspheres were used to measure subepicardial, midwall, and subendocardial flow at critical flow. Measurements and Main Results: Stability of the model and reproducibility of critical flow were studied in a first series of six dogs with the hearts paced at 110 beats/min. Hemodynamics, left ventricular, and segmental myocardial function during critical flow were stable. Subendocardial critical flow was identical with each flow reduction (45%-+ 5, 44% _+ 8, and 43% _+ 5 of baseline myocardial tissue flow). In a second series of six dogs, critical flow was measured at pacing rates 100 beats/min, 150 beats/min, and 100 beats/min with propranolol, 0.1 mg/kg, pretreatment. Critical flows were 38%-+ 5, 55%-+ 6, and 17%-+ 2 of baseline, respectively (p < 0.05). In a third series of six dogs, critical flow was measured during sufentanil, 0.6 i~g/kg/min, and increasing doses of propofol (P0:0.0 mg/kg/h, P4:4.0 mg/kg/h and P8:8.0 mg/kg/h). Heart rate was kept constant at 110 beats/min. When compared with P0, hemodynamic and left ventricular contraction parameters were stable at P4 but were decreased at P8. At P0, critical flow was: 0.63 + 0.14, at P4:0.34-+ 0.09, and at P8:0.25-+ 0.07 mL/min/g (p < 0.05}. Conclusion: Critical myocardial tissue flow was reproducible and sensitive for altered myocardial oxygen needs. The negative inotropic properties of P decreased myocardial oxygen needs during unchanged hemodynamic and left ventricular contraction parameters. A higher P dose depressed left ventricular function.
Journal of Cardiothoracic and Vascular Anesthesia, 1995
To compare the hemodynamic effects, pharmacokinetic profiles, and the need for vasoactive agents ... more To compare the hemodynamic effects, pharmacokinetic profiles, and the need for vasoactive agents between a low (20 micrograms/kg during 15 minutes [group 1; n = 10]) and a high (40 micrograms/kg during 15 minutes [group 2; n = 10]) loading dose of milrinone. Prospective, randomized, double-blind. University hospital. Twenty patients scheduled for elective coronary artery surgery. Weaning from CPB was achieved using a strict protocol. After atrioventricular pacing at 90 beats per minute and preload optimalization, a first weaning attempt was started with only calcium and nitroglycerin as support. If this attempt was unsuccessful (cardiac index &amp;lt; 2L/min/m2), CPB was reinitiated and weaning level 2 was prepared, consisting of inotropic support with milrinone. Patients received either the low (group 1) or the high (group 2) loading dose of milrinone. After the end of the loading dose, a continuous infusion of milrinone of 0.5 micrograms/kg/min was started in both groups. Both groups were comparable regarding preoperative and intraoperative data. Hemodynamic data were comparable in both groups at each time of measurement (p = 0.941). The need for vasoactive medication (norepinephrine [NE]) in order to keep mean arterial pressure &amp;gt; or = 50 mm Hg was significantly higher in group 2 (p = 0.004). Need for NE during the loading infusion was 9.6 +/- 4.9 micrograms (mean +/- SEM) in group 1 and 41.6 +/- 7.6 micrograms in group 2 (p = 0.004). Need for NE during the immediate post-CPB period was also higher in group 2 (16.0 +/- 10.4 micrograms in group 1 and 232.5 +/- 82.8 micrograms in group 2 (p = 0.002)). Plasma clearance of milrinone after CPB was less in both groups than in healthy volunteers. However, clearance of milrinone was significantly higher in group 2 (p = 0.006), and consequently, half-life of milrinone was significantly less in group 2 (p = 0.007). The present results demonstrate that when milrinone is used during weaning from CPB, a loading dose of 20 micrograms/kg provided to similar hemodynamic support a loading dose of 40 micrograms/kg. The need for vasoconstrictive medication was significantly less in the group with the low loading dose.
Journal of Cardiothoracic and Vascular Anesthesia, 1993
This study evaluated the benefit of additional electrocardiographic monitoring of the right preco... more This study evaluated the benefit of additional electrocardiographic monitoring of the right precordial lead V4R for detection of ST segment changes during elective coronary artery bypass surgery in 210 patients. ST segment analysis was performed for leads I, II, CBs, and V4R. ST segment changes were noted in 60 patients. Of these, 32 had combined left-sided and right-sided coronary artery disease (group A), and 26 had only left-sided coronary artery disease on coronary angiography (group B). Lead sensitivity was estimated assuming that all ST segment changes were true positive responses. Sensitivity using a single lead was greatest for lead CBS in the two groups (76% in group A and 76% in group B). Sensitivity for lead I was low in both groups (34% in group A and 26% in group B). Sensitivity for lead Ii was 63% in group A and 52% in group B, and sensitivity for lead VqR METHODS This prospective study was performed in 210 patients who were scheduled for elective CABG. Patients with preexisting, documented arrhythmias, right or left bundle-branch block, valve disease, pacemakers, taking digoxin, or with previous cardiac surgery were excluded. Premeditation consisted of oral lorazepam, 2.5 mg, the evening was 71% in group A but only 37% in group B. Combination of leads VaR and CBS increased sensitivity to 96% in group A. In group B, this lead combination had a sensitivity of 93%. but lead combinations I-CB5-V4R and II-CBs-V4R were more sensitive (97% and 100%. respectively). The monitoring of lead VdR allowed detection of 20% of ST segment changes in group A that would have passed undetected if only leads I, II, and CBS were monitored. These results demonstrate the value of additional electrocardiographic monitoring of the right precordial lead VaR during coronary artery bypass grafting in patients with right-sided coronary artery disease.
Journal of Cardiothoracic and Vascular Anesthesia, 1997
Evaluation of the effects of intravenous CaCl2 on systolic and diastolic function early after sep... more Evaluation of the effects of intravenous CaCl2 on systolic and diastolic function early after separation from cardiopulmonary bypass (CPB) DESIGN: Prospective study University hospital Twenty patients scheduled for elective coronary artery surgery Left ventricular (LV) pressures were measured with fluid-filled catheters. Data were digitally recorded during pressure elevation induced by tilt-up of the legs. Transgastric short-axis echocardiographic views of the LV were simultaneously recorded on videotape. Measurements were obtained before the start of CPB, 10 minutes after termination of CPB, after intravenous administration of CaCl2, 5 mg/kg, and 10 minutes later. Systolic function was evaluated with the slope (Ees, mmHg/mL) of the systolic pressure-volume relation. Diastolic function was evaluated with the chamber stiffness constant (Kc, mmHg/mL) of the diastolic pressure-volume relation. CaCl2 increased Ees from 2.62 +/- 0.46 to 5.58 +/- 0.61 (mean +/- SD), but induced diastolic dysfunction with an increase in Kc from 0.011 +/- 0.006 to 0.019 +/- 0.007. These changes were transient and had disappeared within 10 minutes after administration of CaCl2. CaCl2 early after CPB transiently improved systolic function at the expense of an increase in ventricular stiffness, suggesting temporary diastolic dysfunction.
European Journal of Anaesthesiology, 2001
European Journal of Anaesthesiology, 2002
The effects of administering albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% on ox... more The effects of administering albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% on oxygen transport and left ventricular function were prospectively investigated in different experimental conditions: baseline, fluid load, after 10 min of myocardial ischaemia and after reperfusion. Twenty-seven rabbits received at random one of three colloids in escalating boluses over 10-15 min to achieve left ventricular end-diastolic pressures (LVEDP) between 8 and 10mmHg. A branch of the left anterior descending coronary artery was then temporarily occluded by a ligature and released after 10 min. Myocardial function was assessed using left ventricular pressure recordings and dimension data obtained from ultrasound crystals inserted onto the ventricular wall. Blood was sampled for the determination of oxygen delivery and consumption, the oxygen extraction ratio, acid-base status, and glucose and lactate concentrations. Administration of the colloids similarly increased oxygen delivery and improved left ventricular function in all groups. Peak rate of pressure development (dP/dt(max)) and oxygen delivery were reduced during ischaemia and reperfusion. The decrease in dP/dt(max) was more pronounced in the hydroxyethylstarch group. Administration of albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% had similar effects on oxygen delivery and myocardial function. After ischaemia and during reperfusion, the decrease in myocardial function was most pronounced with hydroxyethylstarch 6%.
European Journal of Anaesthesiology, 1998
European Journal of Anaesthesiology, 2005
Materials and Methods: After Ethics Committee approval, 42 patients aged 19-82 years with ASA Cla... more Materials and Methods: After Ethics Committee approval, 42 patients aged 19-82 years with ASA Class 1-3 were enrolled. Each subject received a dose of 0.6 mg/kg rocuronium after propofol induction. For maintenance of anaesthesia, subjects were randomized to receive propofol ...
European Journal of Anaesthesiology, 2005
BJA: British Journal of Anaesthesia, 1991
We have studied the haemodynamic and myocardial effects of propofol-fentanyl anaesthesia in 12 pa... more We have studied the haemodynamic and myocardial effects of propofol-fentanyl anaesthesia in 12 patients undergoing coronary artery bypass surgery during the pre-bypass period. The induction dose of propofol was 1.5 mg kg-1 and mean infusion rate during maintenance was 4.48 mg kg-1 h-1 (range 1.87-7.24 mg kg-1 h-1). The total dose of fentanyl was 30 micrograms kg-1. The haemodynamic changes indicated myocardial depression and peripheral vasodilatation. Coronary sinus flow and indicators of global myocardial perfusion (myocardial oxygen consumption, myocardial lactate extraction) did not change. Although not excluding regional myocardial ischaemia, these results show that propofol-fentanyl anaesthesia has no major adverse effects on cardiac function.
BJA: British Journal of Anaesthesia, 1987
Although the efficacy of propofol-as an induction agent-has been studied in patients with coronar... more Although the efficacy of propofol-as an induction agent-has been studied in patients with coronary artery disease (Patrick et al., 1985), the haemodynamic effects of a maintenance technique, in which propofol was infused continuously in patients about to undergo elective coronary bypass surgery, have not been reported. This study describes the haemodynamic effects associated with induction of anaesthesia using propofol, and the continuous infusion of propofol (supplemented with fentanyl) during the pre-bypass period. PATIENTS AND METHODS The design of the study was approved by the Ethical Committee of the Antwerp University Hospital. Fifteen patients with good left ventricular function (ejection fraction > 55 % and left ventricular end diastolic pressure < 14 mm Hg), scheduled for elective coronary bypass surgery were included in the study. Mean age was 53 ± 9 (SD) yr, average weight 75.6+11.2 kg and mean body surface area was 1.87 ±0.17 m 2. All patients had angiographically proven coronary artery disease (two-or three-vessel disease); no patient had significant left main coronary artery stenosis. Thirteen patients were taking beta-adrenoreceptor antagonists. Five patients had a history of previous infarction, and four other patients had
BJA: British Journal of Anaesthesia, 1989
Haemodynamic changes and catecholamine responses were measured during anaesthesia with sufentanil... more Haemodynamic changes and catecholamine responses were measured during anaesthesia with sufentanil (total dose 7 micrograms kg-1) supplemented with isoflurane in 14 patients undergoing coronary artery surgery. Isoflurane was used to control systolic arterial pressure, which was allowed to decrease to 100 mm Hg. Mean inspired isoflurane concentration was 0.22 (SD 0.19)% (induction), 0.34 (0.18)% (pre-bypass) and 0.22 (0.17)% (post-bypass). During cardiopulmonary bypass 0.22 (0.13)% isoflurane was administered to control mean perfusion pressure. During induction and the pre-bypass period, significant decreases in systolic and diastolic arterial pressure, systemic vascular resistance and left ventricular stroke work index (LVSWI) (P less than 0.01) were noted. The decrease in LVSWI with unchanged filling pressures indicated myocardial depression. Serum catecholamine concentrations remained at the pre-induction value until cardiopulmonary bypass, when a significant increase was noted. Tracheal intubation, sternotomy and sternal spread were not associated with hypertension or tachycardia. Clinical signs that could reflect myocardial ischaemia were not observed peroperatively. After operation, cardiac enzymes were within the normal clinical range and ECG was unchanged.
In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pr... more In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pressure in the paratracheal region and in the deltoid and supraspinatus muscles, looking for evidence of a potentially dangerous rise in pressure, especially in the paratracheal region. Statistical analysis was used to determine predictable variables of the time of reaching maximum pressure in and between the three regions. Deltoid pressure rose quickly during surgery, and did not drop to baseline levels at the end of surgery. Supraspinatus pressures showed a similar trend but with lower maximum levels of pressure rise. Five patients had an (unexpected) rise in paratracheal pressure, with an absolute maximum of 133.4 mmHg in one. In only two patients, did "10 minutes post-op" paratracheal pressure levels not drop to baseline levels. No respiratory problems occurred during any procedure. There are no variables to predict a potentially dangerous rise in surrounding soft tissue pre...
Acta Orthopaedica Belgica, Nov 1, 2005
In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pr... more In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pressure in the paratracheal region and in the deltoid and supraspinatus muscles, looking for evidence of a potentially dangerous rise in pressure, especially in the paratracheal region. Statistical analysis was used to determine predictable variables of the time of reaching maximum pressure in and between the three regions. Deltoid pressure rose quickly during surgery, and did not drop to baseline levels at the end of surgery. Supraspinatus pressures showed a similar trend but with lower maximum levels of pressure rise. Five patients had an (unexpected) rise in paratracheal pressure, with an absolute maximum of 133.4 mmHg in one. In only two patients, did "10 minutes post-op" paratracheal pressure levels not drop to baseline levels. No respiratory problems occurred during any procedure. There are no variables to predict a potentially dangerous rise in surrounding soft tissue pressure during shoulder arthroscopy. We recommend endotracheal intubation during shoulder arthroscopy.
International Journal of Nursing Studies, 2009
Aim-To study the relationship between nurse work environment, job outcomes and nurse-assessed qua... more Aim-To study the relationship between nurse work environment, job outcomes and nurse-assessed quality of care in the Belgian context. Background-Work environment characteristics are important for attracting and retaining professional nurses in hospitals. The Revised Nursing Work Index (NWI-R) was originally designed to describe the professional nurse work environment in U.S. Magnet Hospitals and subsequently has been extensively used in research internationally. Method-The NWI-R was translated into Dutch to measure the nurse work environment in 155 nurses across 13 units in three Belgian hospitals. Factor analysis was used to identify a set of coherent subscales. The relationship between work environments and job outcomes and nurse-assessed quality of care was investigated using logistic and linear regression analyses. Results: Three reliable, consistent and meaningful subscales of the NWI-R were identified: nurse-physician relations, nurse management at the unit level and hospital management and organizational support. All three subscales had significant associations with several outcome variables. Nurse-physician relations had a significant positive association with nurse job satisfaction, intention to stay the hospital, the nurseassessed unit level quality of care and personal accomplishment. Nurse management at the unit level had a significant positive association with the nurse job satisfaction, nurse-assessed quality of care on the unit and in the hospital, and personal accomplishment. Hospital management and organizational support had a significant positive association with the nurse-assessed quality of care
Pharmacology Biochemistry and Behavior, 2003
Although exogenous opioids alter the responses of animals to tissue-damaging stimuli and therefor... more Although exogenous opioids alter the responses of animals to tissue-damaging stimuli and therefore are the cornerstone in the treatment of acute antinociception, they have profound side effects on ventilation. To diminish ventilatory effects, combination therapies have been advocated. Recent studies reported the effectiveness of the addition of N-methyl-D-aspartate (NMDA) receptor antagonists such as ketamine to morphine in the treatment of acute pain. However, NMDA receptors, together with non-NMDA receptors are known to be involved in the neurotransmission of inspiratory drive to phrenic motoneurons. Co-administration of NMDA and non-NMDA receptor antagonists has been shown to be deleterious to respiratory function. The present study investigated the hypothesis that the association of opioids and NMDA receptor antagonists may add to the impairment of respiratory parameters. In male Wistar rats, combinations of opioids (fentanyl or morphine) at antinociceptive doses and NMDA receptor antagonists (ketamine, 40 mg/kg, or dextromethorphan, 10 mg/kg) at subanesthetic doses were administered intraperitoneally. Antinociception was tested with the tail-withdrawal reaction (TWR) test, while the effect on respiratory parameters was investigated with blood-gas analysis. We found that, in rats, co-administration of NMDA receptor antagonists and opioids may result in an increased respiratory depression as compared to the opioids alone. The effect of the NMDA receptor antagonists on opioid-induced antinociception was limited.
Pediatric Anesthesia, 2004
Journal of Cardiothoracic and Vascular Anesthesia, 2001
To analyze the effects of the pericardium on the length-dependent regulation of myocardial functi... more To analyze the effects of the pericardium on the length-dependent regulation of myocardial function in coronary artery surgery patients. Prospective. University hospital. Patients scheduled for elective coronary artery surgery. In 10 patients, a combined micromanometer transducer conductance catheter was inserted into the left ventricle for measurement of left ventricular pressures and volumes. Consecutive data were obtained during a progressive increase in left ventricular pressures and volumes obtained by leg elevation in closed chest-closed pericardium and open chest-open pericardium conditions. Pericardiotomy did not alter baseline left ventricular hemodynamics. The effects of leg elevation were different, however. In closed chest-closed pericardium conditions, stroke volume and stroke work remained unchanged, whereas these parameters increased in open chest-open pericardium conditions. This increase was related to the increase in end-diastolic volume that was observed in open chest-open pericardium conditions and not in closed chest-closed pericardium conditions. In coronary artery surgery patients, pericardiotomy does not alter baseline left ventricular function. When cardiac load is increased by leg elevation, however, use of the Frank-Starling mechanism is enhanced in open chest-open pericardium conditions.
Journal of Cardiothoracic and Vascular Anesthesia, 1995
To estimate myocardial oxygen needs by studying the effects of reduced coronary blood flow on seg... more To estimate myocardial oxygen needs by studying the effects of reduced coronary blood flow on segmental myocardial function. To study the tolerance of limited oxygen supply to a myocardial segment during propofol administration. Design: A prospective experimental study. Setting: An experimental animal laboratory in a university. Participants: Eighteen adult dogs, weighing 20 to 35 kg. Interventions: Open thorax open pericardium experiments were performed under standard anesthetic conditions. Segment length gauges were placed subendocardially in an anteroapical and in a basal segment. Flow to the anteroapical segment was reduced by tightening a micrometer-controlled snare placed around the second diagonal coronary artery. Left ventricular pressure-length signals allowed for identification of onset of relaxation dysfunction. Myocardial tissue flow at onset of relaxation dysfunction was defined as critical flow. Tracer microspheres were used to measure subepicardial, midwall, and subendocardial flow at critical flow. Measurements and Main Results: Stability of the model and reproducibility of critical flow were studied in a first series of six dogs with the hearts paced at 110 beats/min. Hemodynamics, left ventricular, and segmental myocardial function during critical flow were stable. Subendocardial critical flow was identical with each flow reduction (45%-+ 5, 44% _+ 8, and 43% _+ 5 of baseline myocardial tissue flow). In a second series of six dogs, critical flow was measured at pacing rates 100 beats/min, 150 beats/min, and 100 beats/min with propranolol, 0.1 mg/kg, pretreatment. Critical flows were 38%-+ 5, 55%-+ 6, and 17%-+ 2 of baseline, respectively (p < 0.05). In a third series of six dogs, critical flow was measured during sufentanil, 0.6 i~g/kg/min, and increasing doses of propofol (P0:0.0 mg/kg/h, P4:4.0 mg/kg/h and P8:8.0 mg/kg/h). Heart rate was kept constant at 110 beats/min. When compared with P0, hemodynamic and left ventricular contraction parameters were stable at P4 but were decreased at P8. At P0, critical flow was: 0.63 + 0.14, at P4:0.34-+ 0.09, and at P8:0.25-+ 0.07 mL/min/g (p < 0.05}. Conclusion: Critical myocardial tissue flow was reproducible and sensitive for altered myocardial oxygen needs. The negative inotropic properties of P decreased myocardial oxygen needs during unchanged hemodynamic and left ventricular contraction parameters. A higher P dose depressed left ventricular function.
Journal of Cardiothoracic and Vascular Anesthesia, 1995
To compare the hemodynamic effects, pharmacokinetic profiles, and the need for vasoactive agents ... more To compare the hemodynamic effects, pharmacokinetic profiles, and the need for vasoactive agents between a low (20 micrograms/kg during 15 minutes [group 1; n = 10]) and a high (40 micrograms/kg during 15 minutes [group 2; n = 10]) loading dose of milrinone. Prospective, randomized, double-blind. University hospital. Twenty patients scheduled for elective coronary artery surgery. Weaning from CPB was achieved using a strict protocol. After atrioventricular pacing at 90 beats per minute and preload optimalization, a first weaning attempt was started with only calcium and nitroglycerin as support. If this attempt was unsuccessful (cardiac index &amp;lt; 2L/min/m2), CPB was reinitiated and weaning level 2 was prepared, consisting of inotropic support with milrinone. Patients received either the low (group 1) or the high (group 2) loading dose of milrinone. After the end of the loading dose, a continuous infusion of milrinone of 0.5 micrograms/kg/min was started in both groups. Both groups were comparable regarding preoperative and intraoperative data. Hemodynamic data were comparable in both groups at each time of measurement (p = 0.941). The need for vasoactive medication (norepinephrine [NE]) in order to keep mean arterial pressure &amp;gt; or = 50 mm Hg was significantly higher in group 2 (p = 0.004). Need for NE during the loading infusion was 9.6 +/- 4.9 micrograms (mean +/- SEM) in group 1 and 41.6 +/- 7.6 micrograms in group 2 (p = 0.004). Need for NE during the immediate post-CPB period was also higher in group 2 (16.0 +/- 10.4 micrograms in group 1 and 232.5 +/- 82.8 micrograms in group 2 (p = 0.002)). Plasma clearance of milrinone after CPB was less in both groups than in healthy volunteers. However, clearance of milrinone was significantly higher in group 2 (p = 0.006), and consequently, half-life of milrinone was significantly less in group 2 (p = 0.007). The present results demonstrate that when milrinone is used during weaning from CPB, a loading dose of 20 micrograms/kg provided to similar hemodynamic support a loading dose of 40 micrograms/kg. The need for vasoconstrictive medication was significantly less in the group with the low loading dose.
Journal of Cardiothoracic and Vascular Anesthesia, 1993
This study evaluated the benefit of additional electrocardiographic monitoring of the right preco... more This study evaluated the benefit of additional electrocardiographic monitoring of the right precordial lead V4R for detection of ST segment changes during elective coronary artery bypass surgery in 210 patients. ST segment analysis was performed for leads I, II, CBs, and V4R. ST segment changes were noted in 60 patients. Of these, 32 had combined left-sided and right-sided coronary artery disease (group A), and 26 had only left-sided coronary artery disease on coronary angiography (group B). Lead sensitivity was estimated assuming that all ST segment changes were true positive responses. Sensitivity using a single lead was greatest for lead CBS in the two groups (76% in group A and 76% in group B). Sensitivity for lead I was low in both groups (34% in group A and 26% in group B). Sensitivity for lead Ii was 63% in group A and 52% in group B, and sensitivity for lead VqR METHODS This prospective study was performed in 210 patients who were scheduled for elective CABG. Patients with preexisting, documented arrhythmias, right or left bundle-branch block, valve disease, pacemakers, taking digoxin, or with previous cardiac surgery were excluded. Premeditation consisted of oral lorazepam, 2.5 mg, the evening was 71% in group A but only 37% in group B. Combination of leads VaR and CBS increased sensitivity to 96% in group A. In group B, this lead combination had a sensitivity of 93%. but lead combinations I-CB5-V4R and II-CBs-V4R were more sensitive (97% and 100%. respectively). The monitoring of lead VdR allowed detection of 20% of ST segment changes in group A that would have passed undetected if only leads I, II, and CBS were monitored. These results demonstrate the value of additional electrocardiographic monitoring of the right precordial lead VaR during coronary artery bypass grafting in patients with right-sided coronary artery disease.
Journal of Cardiothoracic and Vascular Anesthesia, 1997
Evaluation of the effects of intravenous CaCl2 on systolic and diastolic function early after sep... more Evaluation of the effects of intravenous CaCl2 on systolic and diastolic function early after separation from cardiopulmonary bypass (CPB) DESIGN: Prospective study University hospital Twenty patients scheduled for elective coronary artery surgery Left ventricular (LV) pressures were measured with fluid-filled catheters. Data were digitally recorded during pressure elevation induced by tilt-up of the legs. Transgastric short-axis echocardiographic views of the LV were simultaneously recorded on videotape. Measurements were obtained before the start of CPB, 10 minutes after termination of CPB, after intravenous administration of CaCl2, 5 mg/kg, and 10 minutes later. Systolic function was evaluated with the slope (Ees, mmHg/mL) of the systolic pressure-volume relation. Diastolic function was evaluated with the chamber stiffness constant (Kc, mmHg/mL) of the diastolic pressure-volume relation. CaCl2 increased Ees from 2.62 +/- 0.46 to 5.58 +/- 0.61 (mean +/- SD), but induced diastolic dysfunction with an increase in Kc from 0.011 +/- 0.006 to 0.019 +/- 0.007. These changes were transient and had disappeared within 10 minutes after administration of CaCl2. CaCl2 early after CPB transiently improved systolic function at the expense of an increase in ventricular stiffness, suggesting temporary diastolic dysfunction.
European Journal of Anaesthesiology, 2001
European Journal of Anaesthesiology, 2002
The effects of administering albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% on ox... more The effects of administering albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% on oxygen transport and left ventricular function were prospectively investigated in different experimental conditions: baseline, fluid load, after 10 min of myocardial ischaemia and after reperfusion. Twenty-seven rabbits received at random one of three colloids in escalating boluses over 10-15 min to achieve left ventricular end-diastolic pressures (LVEDP) between 8 and 10mmHg. A branch of the left anterior descending coronary artery was then temporarily occluded by a ligature and released after 10 min. Myocardial function was assessed using left ventricular pressure recordings and dimension data obtained from ultrasound crystals inserted onto the ventricular wall. Blood was sampled for the determination of oxygen delivery and consumption, the oxygen extraction ratio, acid-base status, and glucose and lactate concentrations. Administration of the colloids similarly increased oxygen delivery and improved left ventricular function in all groups. Peak rate of pressure development (dP/dt(max)) and oxygen delivery were reduced during ischaemia and reperfusion. The decrease in dP/dt(max) was more pronounced in the hydroxyethylstarch group. Administration of albumin 5%, hydroxyethylstarch 6% and succinylated gelatine 4% had similar effects on oxygen delivery and myocardial function. After ischaemia and during reperfusion, the decrease in myocardial function was most pronounced with hydroxyethylstarch 6%.
European Journal of Anaesthesiology, 1998
European Journal of Anaesthesiology, 2005
Materials and Methods: After Ethics Committee approval, 42 patients aged 19-82 years with ASA Cla... more Materials and Methods: After Ethics Committee approval, 42 patients aged 19-82 years with ASA Class 1-3 were enrolled. Each subject received a dose of 0.6 mg/kg rocuronium after propofol induction. For maintenance of anaesthesia, subjects were randomized to receive propofol ...
European Journal of Anaesthesiology, 2005
BJA: British Journal of Anaesthesia, 1991
We have studied the haemodynamic and myocardial effects of propofol-fentanyl anaesthesia in 12 pa... more We have studied the haemodynamic and myocardial effects of propofol-fentanyl anaesthesia in 12 patients undergoing coronary artery bypass surgery during the pre-bypass period. The induction dose of propofol was 1.5 mg kg-1 and mean infusion rate during maintenance was 4.48 mg kg-1 h-1 (range 1.87-7.24 mg kg-1 h-1). The total dose of fentanyl was 30 micrograms kg-1. The haemodynamic changes indicated myocardial depression and peripheral vasodilatation. Coronary sinus flow and indicators of global myocardial perfusion (myocardial oxygen consumption, myocardial lactate extraction) did not change. Although not excluding regional myocardial ischaemia, these results show that propofol-fentanyl anaesthesia has no major adverse effects on cardiac function.
BJA: British Journal of Anaesthesia, 1987
Although the efficacy of propofol-as an induction agent-has been studied in patients with coronar... more Although the efficacy of propofol-as an induction agent-has been studied in patients with coronary artery disease (Patrick et al., 1985), the haemodynamic effects of a maintenance technique, in which propofol was infused continuously in patients about to undergo elective coronary bypass surgery, have not been reported. This study describes the haemodynamic effects associated with induction of anaesthesia using propofol, and the continuous infusion of propofol (supplemented with fentanyl) during the pre-bypass period. PATIENTS AND METHODS The design of the study was approved by the Ethical Committee of the Antwerp University Hospital. Fifteen patients with good left ventricular function (ejection fraction > 55 % and left ventricular end diastolic pressure < 14 mm Hg), scheduled for elective coronary bypass surgery were included in the study. Mean age was 53 ± 9 (SD) yr, average weight 75.6+11.2 kg and mean body surface area was 1.87 ±0.17 m 2. All patients had angiographically proven coronary artery disease (two-or three-vessel disease); no patient had significant left main coronary artery stenosis. Thirteen patients were taking beta-adrenoreceptor antagonists. Five patients had a history of previous infarction, and four other patients had
BJA: British Journal of Anaesthesia, 1989
Haemodynamic changes and catecholamine responses were measured during anaesthesia with sufentanil... more Haemodynamic changes and catecholamine responses were measured during anaesthesia with sufentanil (total dose 7 micrograms kg-1) supplemented with isoflurane in 14 patients undergoing coronary artery surgery. Isoflurane was used to control systolic arterial pressure, which was allowed to decrease to 100 mm Hg. Mean inspired isoflurane concentration was 0.22 (SD 0.19)% (induction), 0.34 (0.18)% (pre-bypass) and 0.22 (0.17)% (post-bypass). During cardiopulmonary bypass 0.22 (0.13)% isoflurane was administered to control mean perfusion pressure. During induction and the pre-bypass period, significant decreases in systolic and diastolic arterial pressure, systemic vascular resistance and left ventricular stroke work index (LVSWI) (P less than 0.01) were noted. The decrease in LVSWI with unchanged filling pressures indicated myocardial depression. Serum catecholamine concentrations remained at the pre-induction value until cardiopulmonary bypass, when a significant increase was noted. Tracheal intubation, sternotomy and sternal spread were not associated with hypertension or tachycardia. Clinical signs that could reflect myocardial ischaemia were not observed peroperatively. After operation, cardiac enzymes were within the normal clinical range and ECG was unchanged.