Dynamic evaluation of fluid shifts during normothermic and hypothermic cardiopulmonary bypass in piglets (original) (raw)
Related papers
Acta Anaesthesiologica Scandinavica, 2001
Background: Hypothermia, commonly used for organ protection during cardiopulmonary bypass (CPB), has been associated with changes in plasma volume, hemoconcentration and microvascular fluid shifts. Fluid pathophysiology secondary to hypothermia and the mechanisms behind these changes are still largely unknown. In a recent study we found increased fluid needs during hypothermic compared to normothermic CPB. The aim of the present study was to characterize the distribution of the fluid given to maintain normovolemia. In addition, we wanted to investigate the quantity and quality of the fluid extravasated during hypothermic compared to normothermic CPB. Methods: Two groups of anesthetized piglets were studied during 2 h of hypothermic (28 aeC) (nΩ7) or normothermic (38 aeC) (nΩ7) CPB. Net fluid balance (inputªoutput) was recorded. Changes in colloid osmotic pressures of plasma (COP p ) and interstitial fluid (COP i ), plasma volume (PV), hemoglobin (Hb), hematocrit (HCT), mean corpuscular volume (MCV), s-osmolality, s-albumin and s-total protein was followed throughout the experiments. Fluid extravasation rate was calculated. In addition, total tissue water content was measured and compared with a control group (nΩ6) (no CPB). Results: During hypothermic compared with normothermic CPB, the average net positive fluid balance from 10-120 min of
Acta Anaesthesiologica Scandinavica, 2003
Background: Hypothermic cardiopulmonary bypass (CPB) is associated with capillary fluid leak and edema generation which may be secondary to hemodilution, inflammation and hypothermia. We evaluated how hypothermia and different cooling strategies influenced the fluid extravasation rate during CPB. Methods: Fourteen piglets were given 60 min normothermic CPB, followed by randomization to two groups: 1: rapid cooling (RC-group) ($15 min to 28 C); 2: slow cooling (SC-group) ($60 min to 28 C). Ringer's solution was used as CPB prime and for fluid supplementation. Fluid input/losses, plasma volume, colloid osmotic pressures (plasma, interstitial fluid), hematocrit, serum-proteins and total tissue water (TTW) were measured and fluid extravasation rates calculated. Results: Start of normothermic CPB resulted in a 25% hemodilution. During the first 5Ð10 min the fluid level of the reservoir fell markedly due to an intravascular volume loss necessitating fluid supplementation. Thereafter a steady state was reached with a constant fluid need of 0.14 AE 0.04 ml kg À1 min À1 . After start of cooling the fluid needs increased in the following 30 min to 0.91AE 0.11 ml kg À1 min À1 in the RC group (P < 0.001) and 0.63 AE 0.10 ml kg À1 min À1 in the SC-group (P < 0.001) with no statistical between-group differences.
Acta Anaesthesiologica Scandinavica, 2002
Background: Cardiopulmonary bypass (CPB) as used for cardiac surgery and for rewarming individuals suffering deep accidental hypothermia is held responsible for changes in microvascular fluid exchange often leading to edema and organ dysfunction. The purpose of this work is to improve our understanding of fluid pathophysiology and to explore the implications of the changes in determinants of transcapillary fluid exchange during CPB with and without hypothermia. This investigation might give indications on where to focus attention to reduce fluid extravasation during CPB. Methods: Published data on ''Starling variables'' as well as reported changes in fluid extravasation, tissue fluid contents and lymph flow were analyzed together with assumed/estimated values for variables not measured. The analysis was based on the Starling hypothesis where the transcapillary fluid filtration rate is given by:
Critical Care, 1999
O Ob bj je ec ct ti iv ve es s: : Acute renal failure (ARF) is a common complication following open heart surgery especially in infants. Effects of blood viscosity on renal function are well known, but have not been investigated in cardiopulmonary bypass (CPS) as yet. M Ma at te er ri ia al l a an nd d m me et th ho od ds s: : We investigated blood viscosity and different markers of glomerular and tubular renal function in a group of 37 infants below 18 month of age, receiving CPS surgery for different diagnoses. In an experimental setting, we investigated 28 isolated pig-kidneys with different hematocrits in an autologous blood perfused model. R Re es su ul lt ts s: : In infants, creatinine clearance decreased and urinary excretion of albumin and β-NAG increased during the aortic cross clamp time (AT) and during the first hours following operation, indicating moderate glomerular and tubular damage. During AT, blood was hemodiluted to a hemoglobin of 8.4 ± 0.4 g/dl. Thus, blood viscosity during AT and hypothermia was slightly below pre-CPB values. Lower blood viscosity was related to less renal damage (P < 0.01). In isolated pig-kidneys, group I (n = 14) was perfused with a hemoglobin of 10.2 ± 0.3 g/dl and group II (n = 14) was hemodiluted to 6.5 ± 0.9 g/dl. Group II kidneys showed lower vascular resistance, elevated creatinine clearance, elevated oxygen consumption and elevated sodium reabsorption (P < 0.05). C Co on nc cl lu us si io on ns s: : Reducing blood viscosity below physiological values improves tubular as well as glomerular function under CPB conditions. Thus we hold hemodilution to be an appropriate method for optimizing CPB procedures.
Anesthesia & Analgesia, 2006
The use of miniaturized cardiopulmonary bypass (CPB) circuits and avoidance of cardioplegic arrest are attempts to reduce the inflammatory response to cardiac surgery. We studied the effects of beating heart surgery (BHS) with assistance of simplified bypass systems (SBS) on global hemodynamics, myocardial function and the inflammatory response to CPB. We hypothesized that the use of SBS was associated with less hemodynamic instability after CPB resulting from attenuation of the inflammatory response when compared with surgery performed with a conventional CPB (cCPB) circuit. Forty-five patients undergoing coronary artery bypass grafting were prospectively studied. Fifteen patients were randomized to the use of a cCPB circuit, cold crystalloid cardioplegia, and moderate hypothermia. Two groups of 15 patients underwent BHS during normothermia with assistance of two different SBS consisting of only blood pump and oxygenator. Hemodynamic variables were assessed with transpulmonary thermodilution and transesophageal echocardiography. Plasma levels of proinflammatory and antiinflammatory mediators were measured perioperatively. After CPB, variables of global hemodynamics and systolic ventricular function did not differ among groups. Left ventricular diastolic function was impaired after CPB equally in all groups (P Ͻ 0.01 versus pre-CPB). At the end of surgery, there was more need for vasopressor (norepinephrine) support in both SBS groups than in the cCPB group (P Ͻ 0.01). After CPB, the release of interleukin (IL)-6 did not differ significantly among groups, whereas plasma levels of IL-10 were higher in the cCPB group (P Ͻ 0.01 versus SBS). The extent of myocardial necrosis (Troponin T) was comparable in all groups. We conclude that in our study, miniaturizing bypass systems and avoidance of cardioplegic arrest were not effective in improving hemodynamic performance and in attenuating the proinflammatory immune response after CPB.
The Hemodynamic Responses to Hypothermic and Normothermic Cardiopulmonary Bypass
Turkish Journal of Medical Sciences, 2001
This prospective randomized clinical study was designed to assess and compare the effects of normothermic and hypothermic nonpulsative cardiopulmonary bypass in patients with mitral valve replacement. Forty patients undergoing elective mitral valve replacement were randomly divided into two groups according to the temperature of perfusion. Group N (15 patients) underwent normothermic cardiopulmonary perfusion and Group H (25 patients) underwent hypothermic cardiopulmonary perfusion. These groups were compared using clinical and electrocardiographic criteria and cardiovascular evaluation parameters. Quantitative data were analyzed using the paired Student t test. While there was a significant increment in heart rate in Group N in relation to preoperative values, there was no change in heart rate in Group H. Increasing values in systemic vascular resistance (SVR) parameters were detected in both groups. Oxygen consumption (VO 2) values decreased in Group N in relation to Group H. There was no significant change in alveolar-arterial O 2 difference (DO 2) values between these two groups. These results indicate that the temperature of cardiopulmonary perfusion had no effect on the immediate postoperative values but did cause an increase in heart rate in the normothermic group.
The Journal of Thoracic and Cardiovascular Surgery, 2005
Objective: Hypothermic cardiopulmonary bypass is associated with increased fluid extravasation. This study aimed to compare whether iso-oncotic priming solutions, in contrast to crystalloids, could reduce the cold-induced fluid extravasation during cardiopulmonary bypass in piglets. Methods: Three groups were studied: the control group (CT group; n ϭ 10), the albumin group (Alb group; n ϭ 7), and the hydroxyethyl starch group (HES group; n ϭ 7). Prime (1000 mL) and supplemental fluid were acetated Ringer solution, 4% albumin, and 6% hydroxyethyl starch, respectively. After 1 hour of normothermic cardiopulmonary bypass, hypothermic cardiopulmonary bypass (cooling to 28°C within 15 minutes) was initiated and continued to 90 minutes. Fluid needs, plasma volume, changes in colloid osmotic pressure in plasma and interstitial fluid, hematocrit levels, and tissue water content were recorded, and protein masses and fluid extravasation rates were calculated. Results: Colloid osmotic pressure in plasma decreased immediately after the start of cardiopulmonary bypass in the CT group but remained stable in the Alb and HES groups. Colloid osmotic pressure in interstitial fluid tended to decrease in the CT group and remained unchanged in the Alb group, whereas a slight increase was observed in the HES group. Immediately after the start of cooling, fluid extravasation rates increased from 0.15 Ϯ 0.10 to 0.64 Ϯ 0.12 mL • kg Ϫ1 • min Ϫ1 in the CT group, whereas no such increase was observed in the Alb and HES groups. The changes in fluid extravasation rates were reflected by corresponding changes in tissue water content. Conclusion: The use of albumin or hydroxyethyl starch as prime to preserve the colloid osmotic pressure during cardiopulmonary bypass causes a reduction in the cold-induced fluid extravasation compared with that seen with crystalloids. Albumin seems more effective than hydroxyethyl starch to limit cold-induced fluid shifts during cardiopulmonary bypass.
The Journal of Thoracic and Cardiovascular Surgery, 2004
Objective: Hypothermic cardiopulmonary bypass is associated with capillary fluid leakage, resulting in edema and occasionally organ dysfunction. Systemic inflammatory activation is considered responsible. In some studies methylprednisolone has reduced the weight gain during cardiopulmonary bypass. Vitamin C and ␣-trinositol have been demonstrated to reduce the microvascular fluid and protein leakage in thermal injuries. We therefore tested these three agents for the reduction of cold-induced fluid extravasation during cardiopulmonary bypass.
Effect of Hypothermia on Arterial Versus Venous Blood Gases During Cardiopulmonary Bypass in Man
The Journal of ExtraCorporeal Technology
The effect of moderate hypothermia on arterial versus venous blood gases was investigated in 11 patients during cardiopulmonary bypass. The pump and oxygen flows were maintained at a constant flow of 2.4 L/m2/min throughout bypass. After going on bypass, the central venous blood temperature was dropped to 27.8 ± 0.6°C, and after surgery was completed the patients were rewarmed to 37.0°C. Arterial and venous blood gases were sampled simultaneously from the arterial outlet and the venous inlet lines of the oxygenator every two degrees of temperature change until37°C was reached. The effect of temperature changes on pCO2 simulated the alpha-stat strategy of acid-base regulation; the temperature-corrected arterial and venous pCO2 varied directly and the corrected pH varied inversely with body temperature, while the uncorrected pCO2 and pH did not show a significant changE- with changes of body temperature. The arterial pO2 whether corrected or uncorrected, as well as the venous oxygen s...