Hypothermia In Cardiac Surgery Research Articles

Relationship Between the Use of Topical Hypothermia with Ice Water to Postoperative Pulmonary Complications of Coronary Artery Bypass Graft

Introduction: Open heart surgery such as coronary artery bypass graft (CABG) is a heart surgery technique that uses a machine cardiopulmonary bypass (CPB) which can cause postoperative complications such as systemic inflammatory response syndrome (SIRS) and myocardial damage. Myocardial protection can be achieved through topical hypothermia techniques by lowering the heart temperature using a cold solution or ice cubes. Although several studies have shown its benefit in protecting the myocardium, the use of topical hypothermia remains controversial due to its uneven cooling effect and risk of tissue injury. This study aims to evaluate the relationship between the use of topical hypothermia of ice water and pulmonary complications of open heart surgery.
 Methods: This research is an analytical observational cohort retrospective comparison of pulmonary complications postoperatively in cardiac surgery patients who received systemic cardioplegia alone versus those who received a combination of systemic cardioplegia and topical hypothermia. Data collection was carried out using techniques consecutive sampling.
 Results: Of the 32 research subjects, the results of the analysis showed that the use of topical hypothermia did not have a statistically significant relationship (p>0.05) on the incidence of leukocytosis, pulmonary edema, duration of surgery, duration of ventilator use, duration of hospitalization, and mortality compared to the group that only received systemic cardioplegia. There was a significant relationship (p<0.05) between the incidence of pleural effusion in the topical hypothermia group.
 Conclusion: The use of topical hypothermia in cardiac surgery has a significant association with a higher incidence of pleural effusion.

The Role of Deep Hypothermia in Cardiac Surgery.

Hypothermia is defined as a decrease in body core temperature to below 35 °C. In cardiac surgery, four stages of hypothermia are distinguished: mild, moderate, deep, and profound. The organ protection offered by deep hypothermia (DH) enables safe circulatory arrest as a prerequisite to carrying out cardiac surgical intervention. In adult cardiac surgery, DH is mainly used in aortic arch surgery, surgical treatment of pulmonary embolism, and acute type-A aortic dissection interventions. In surgery treating congenital defects, DH is used to assist aortic arch reconstructions, hypoplastic left heart syndrome interventions, and for multi-stage treatment of infants with a single heart ventricle during the neonatal period. However, it should be noted that a safe duration of circulatory arrest in DH for the central nervous system is 30 to 40 min at most and should not be exceeded to prevent severe neurological adverse events. Personalized therapy for the patient and adequate blood temperature monitoring, glycemia, hematocrit, pH, and cerebral oxygenation is a prerequisite and indispensable part of DH.

Der Einfluss der moderaten Hypothermie bei 28 °C auf die Gerinnungs- und Thrombozytenfunktion – Untersuchung in einem In-vitro-Chandler-Loop-Modell

In the use of hypothermia in cardiac surgery an increased risk of bleeding is noticeable intra- and postoperatively. So far, the effects on coagulation and platelets caused by complex interactions between the extracorporeal circulation (ECC), surgical trauma and the effects of hypothermia prevent a clinical investigation of the cause of hypothermia associated bleeding in cardiac surgery. Methods: Using a Chandler-Loop blood flow model the effects of hypothermia could be studied under in-vitro conditions isolated from other competing factors. In the experimental group blood samples of three adult probands were cooled down from 37 °C to 28 °C and reheated at standardized temperature and flow conditions. During the measurements blood samples were taken at four checkpoints from the Chandler-Loops. A normothermic series of measurements served as a control group. Coagulation was examined using thrombelastometry and platelet function using impedance aggregometry. Results: Hypothermia irregularly caused a reduced coagulation; however, the platelet function seemed to be unaffected or only reversibly affected. Therefore, a decreased platelet function associated to hypothermia could not be detected via impedance aggregometry. In both groups the effects caused by the circulation in the Chandler-Loops on coagulation and platelet function were more pronounced than the effects caused by hypothermia. Discussion: The effects of hypothermia on coagulation seem to be not as pronounced and uniform as in other studies described. It is instead to assume that only specific components are impaired by cooling whereas the rotation in the Chandler-Loops always leads to measurable contact reactions. The results of the thrombelastomtry indicate that the cause for an impaired coagulation under hypothermia are reduced protein kinetics and a decreased platelet function. The reversible effects of hypothermia on platelets may account for the lack of measurable alterations in platelet function when using the Multiplate method. This being the case hypothermia caused impairment of platelet function could not be detected using the Multiplate method under clinical conditions.

Unrecognized platelet physiology is the cause of rewarming deaths in accidental hypothermia and neonatal cold injury

BackgroundThe lack of improvement in prognosis of accidental hypothermia and neonatal cold injury suggests that a major cause of mortality has not been appreciated. Aim of the articleTo show that thrombocytopenia that deepens on rewarming under certain conditions is that missing factor. Scientific basisBelow 34 °C the first stage of aggregation is accentuated, the platelets are more sensitive to ADP and aggregation studies show an increased response “first stage hyper aggregation”. We have confirmed that the irreversible second stage of platelet aggregation does not occur below 34 °C. On rewarming, the first stage of aggregation is followed by disaggregation. When platelets are warmed to 34 °C the potential exists for the platelets to undergo an irreversible second stage of aggregation “second stage platelet hyper aggregation” that can cause a further drop in platelet count and a bleeding diathesis. This only occurs if the platelets have been sufficiently primed when cold and may not be appreciated if platelet counts are not followed. Significance of this data and correlation with the literatureThis thesis explains many other open questions. Why has the overall prognosis remained without improvement over the last half century? Why hypothermic cardiac surgery is free of this problem? Why the depth of hypothermia is alone not prognostic? Has following platelet counts been associated with improved prognosis? Why cardiac arrest does not affect prognosis? Why some patients die suddenly after recovering from hypothermia? Why are so many different rewarming techniques used? Why is the prognosis better in hypothermic suicide attempts? What is the pathophysiological explanation for reversible sequestration of platelets to the liver and spleen in hypothermia? Is DIC (diffuse intravascular coagulation) a problem in hypothermia? And how this new approach could improve prognosis? ConclusionPrognosis can be improved by following platelet counts during rewarming. In patients with prolonged hypothermia, this will show a life-threatening drop in such counts easily treated by platelet infusion.

The first Case of Circulatory Arrest in deep Hypothermia in Cardiac Surgery in Mali

The authors report the case of circulatory arrest in deep hypothermia during the closure of an arterial duct associated with significant mitral insufficiency for mitral replacement in an underdeveloped country such as Mali. This circulatory arrest technique used in major European and American heart surgery centers for the management of complex heart disease. It constitutes a real challenge for us to report the first case of circulatory arrest in the management of the persistent arterial canal associated with mitral insufficiency including simple operative consequences.

Incidentally discovered cold hemagglutinin disease with massive blood clots in the cardioplegia line and coronary artery, during coronary artery bypass graft

BackgroundCold hemagglutinin disease (CHAD) is a rare autoimmune disease, in which patients manifest symptoms when the body temperature decreases. It causes critical problems with blood clotting and hemolysis during hypothermia in cardiac surgery. Although various methods are recommended, the CHAD discovered incidentally during cardiac surgery is still a clinical challenge.Case presentationA 76-year-old male visited our hospital for chest pain. Angiography revealed unstable angina, left-main and three-vessel disease. We performed coronary artery bypass graft (CABG) with cardiopulmonary bypass after heparin injection. Shortly after aorta cross-clamping (ACC) and infusion of cold blood cardioplegia, we found massive blood clots in the cardioplegia line. Upon suspicion of CHAD, we raised the temperature and infused warm blood cardioplegia in a retrograde manner. After performing cardiac arrest, we opened the coronary artery and found blood clots in the coronary artery. We eliminated the clots and washed with warm crystalloid cardioplegia simultaneously in an antegrade and retrograde manner. During the ACC, warm cardioplegia was infused every 15 min, via retrograde and antegrade techniques simultaneously. After distal anastomosis of the saphenous venous graft (SVG) to the coronary artery, we performed a direct SVG warm cardioplegia infusion. Finally, before the proximal SVG anastomosis to the aorta, we used warm cardioplegia to eliminate the remaining microemboli. The cold reactive protein test showed a positive result. The patient was discharged without any complications.ConclusionIn this rare case, we incidentally discovered CHAD associated with massive blood clots in the cardioplegia line and the coronary artery, during CABG. However, we performed CABG without any complications using a reasonable and appropriate cardioplegia infusion technique, including direct SVG warm cardioplegia infusion.

Levetiracetam-mediated improvement of decreased NMDA-induced glutamate release from nerve terminals during hypothermia

A combination of a beneficial neuroprotectant, hypothermia, with targeted medication is a perspective therapeutic approach. Here, we analyzed both non-specific (deep and profound hypothermia, 27 °C and 17 °C, respectively) and targeted (anticonvulsant drug levetiracetam) modulation of l-[14C]glutamate release induced by activation of presynaptic NMDA, AMPA, and kainate receptors in rat brain nerve terminals (synaptosomes). Gradual dynamics of hypothermia-mediated decrease in synaptosomal l-[14C]glutamate release evoked by the receptor agonists NMDA-, AMPA-, and kainate (250 μM) has been demonstrated that can be of value for the justification of optimal temperature regimes in therapeutic hypothermia. 250 μM NMDA-induced l-[14C]glutamate release from nerve terminals was higher in the presence of levetiracetam (100 μM) as compared to that without the drug. Despite levetiracetam effects decreased in hypothermia, combined application of hypothermia and levetiracetam resulted in higher NMDA-induced l-[14C]glutamate release from nerve terminals as compared to that without the drug. These effects were not revealed for synaptosomal AMPA- and kainate-induced l-[14C]glutamate release in the presence of levetiracetam at the similar concentration. Therefore, levetiracetam administration significantly mitigated a hypothermia-induced decrease in NMDA receptor response at the presynaptic level and can be used for the targeted neurocorrection to reduce side effects of hypothermia in cardiac surgery. However, levetiracetam-mediated improvement of NMDA receptor response is not applicable in stroke, brain trauma and neonatal asphyxia therapies, where the main neuroprotective action of hypothermia is associated with prevention of damaging consequence of pre-existing acute glutamate exitotoxicity.

Impact of temperature on the Narcotrend Index during hypothermic cardiopulmonary bypass in children with sevoflurane anesthesia.

During cardiopulmonary bypass (CPB) in children, anesthesia maintained by sevoflurane administered via the oxygenator is increasingly common. Anesthetic uptake and requirement may be influenced by the non-physiological conditions during hypothermic CPB. Narcotrend-processed EEG monitoring may, therefore, be useful to guide the administration of sevoflurane during this phase. The objective of this prospective, clinical, observational study was to assess the correlation between body temperature, Narcotrend Index (NI) and administered sevoflurane in children during CPB. Forty-four children aged 0 to 10 years undergoing hypothermic cardiac surgery were studied. On bypass, anesthesia was maintained with sevoflurane administered via the oxygenator of the heart-lung machine. Nasopharyngeal temperature, NI and minimum alveolar concentration (MAC) of sevoflurane were recorded in intervals of 10 minutes. Expiratory gas was sampled from the oxygenator's sole expiratory port via a separate connecting line and the MAC was measured by the agent analyzer of the anesthesia machine. Raw (r = 0.74) and corrected (r = 0.73) r-values show that narcosis depth (as indicated by NI) can primarily be explained by the interaction of MAC and temperature. The analysis of variance (without the interaction term) confirms the significant and independent association of both factors, MAC (p<0.004, 95%CI: 0.19 to 0.46) and temperature (p<0.0001, 95%CI: 0.68 to 0.78), with the NI. During hypothermia, sevoflurane had been reduced significantly (r = 0.41, p<0.0001, 95%CI: 0.33 to 0.48). Perfusionists and anesthetists should be aware of the results of processed electroencephalograph (EEG) monitoring during CPB. Sevoflurane requirements differ inter-individually; they may decrease during cooling and increase during rewarming. Therefore, it seems reasonable to include the results of processed EEG monitoring when administering sevoflurane during CPB in children, but further studies are necessary to confirm this thesis.

Bentall Surgery in a Patient with Cold Agglutinin and Antiphospholipid Antibody: Double Trouble

Cold agglutinin disease is an uncommon disease with potential to cause hemolysis and thrombosis during hypothermic cardiac surgery. Antiphospholipid syndrome is also rare disease with hypercoagulation tendacy. Perioperative management of both these diseases is challenging. We present successful perioperative management of high risk Bentall surgery in patient with both these dreadful diseases.

Role of topical application of iced slush in the development of phrenic nerve palsy after cardiac surgery

Phrenic nerve palsy (PNP) is a well-recognized complication after cardiac surgery which might occur as a result of topical myocardial cooling, direct injury or ischemia. It can result in deleterious respiratory effects especially in children and in patient with chronic obstructive pulmonary disease which adversely affect recovery and increase the length of ICU and hospital stay. Topical application of iced slush has been used for decades in hypothermic cardiac surgery, the effect of the direct contact between the iced slush and phrenic nerve might increase the incidence of nerve palsy and diaphragmatic dysfunction. Recently normothermic cardiac surgery has been employed largely to avoid the adverse effects of hypothermia.

Hypothermic cardiopulmonary bypass surgery in a 7-year-old boy with a cold agglutinin

Dear Editor, Cold agglutinins (CA) are predominately IgM auto-antibodies that optimally react with surface antigens on red blood cells (RBCs) at low temperatures. Subsequently, agglutination of RBCs can occur followed by complement fixation and haemolysis. CAs seldom cause significant intraand extravascular haemolysis under normothermic conditions. However, they could be of relevance in patients undergoing cardiac surgery when hypothermic cardiopulmonary bypass (CPB) and cardioplegia are used [1]. There are conflicting opinions in the literature about screening patients for CAs prior to hypothermic CPB. CAs are rare and low levels can be found in healthy individuals. The incidence of CAs in screened cardiac surgery patients is approximately 0.8–4 % [1–4]. Although serious complications (haemolysis, micro-vascular occlusion and organ failure) have been described, it has also been demonstrated that patients with low titre, low thermal amplitude CAs can safely undergo CPB [1–4]. Therefore, and following Dutch guidelines recommendations (CBO consensus Bloedtransfusie, http://www.cbo.nl/thema/Richtlijnen/ Overzicht-richtlijnen/Bloedtransfusie/), we do not screen for CAs in adults. However, as described also by others recently, we do perform screening for CAs in children undergoing cardiac surgery for which deep hypothermia is indicated [5]. A 7-year-old boy was referred for serological testing prior to hypothermic cardiac surgery. The patient’s blood group was O positive and antibody screening tests were negative. The cold agglutinin assay (saline, 16 °C) revealed the presence of a cold autoantibody with IH specificity. CAs are often directed against the Ii blood group collection [1]. Anti-IH antibodies have been implicated as the cause of a haemolytic transfusion reaction in a couple of cases [6–8]. CAs are generally produced in response to infections or secondary to a lymphoproliferative disorder [9]. Our patient had recently been treated with antibiotics for an infection. The importance of a CA is determined by the thermal amplitude (highest temperature at which the antibody binds to RBCs) and titre. The IH-antibody in our patient displayed wide thermal amplitude (28 °C; titre 1:2). Because of the associated risk of intravascular haemolysis during CPB, and the fact that postponing the elective surgery was safe for the patient, the procedure was cancelled. The presence of CAs is often transient and therefore the thermal amplitude of the antibody was determined periodically. The thermal amplitude decreased slowly to 24 °C after 3 months (titre 1:1) and 22 °C after 5 months (Fig. 1). After 7 months, the thermal amplitude of the antibody remained stable and we decided to perform the procedure under less extensive hypothermic conditions. The patient was cooled to 24.9 °C and surgery was performed successfully. The antibody did not show any reactivity at this temperature and accordingly, the patient did not show signs of hemolysis. The patient received 2 units of RBC, as a consequence of the CPB procedure, and had stable post-surgery haemoglobin of 11.3 g/dL, without any signs of hemolysis. In conclusion, CAs can cause haemolysis in patients undergoing hypothermic cardiac surgery. Although screening for CAs in all patients is not recommended it can be useful in specific patient groups (e.g. children undergoing I. Hubeek :W. W. van Solinge :K. M. K. de Vooght Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands

Effectiveness of an Underbody Forced Warm-Air Blanket during Coronary Artery Bypass Surgery in the Prevention of Postoperative Hypothermia: A Prospective Controlled Randomized Clinical Trial

Introduction: Perioperative hypothermia in cardiac surgery is associated with adverse outcome. The aim of this investigation was to study whether an underbody forced-air warming blanket during coronary artery bypass graft surgery with normothermic cardiopulmonary bypass can prevent postoperative hypothermia. Methods: After Medical Ethics Committee approval, 60 low-risk cardiac surgery patients at random were assigned into a group that received standard thermal care management (control group n = 30) and a group that received the underbody forced-air warming system plus the standard thermal care (intervention group n = 30). Results: The temperature after-drop from the end of cardiopulmonary bypass to arrival in the ICU was less in the intervention group versus control group (0.4°C ± 0.3°C vs 0.6°C ± 0.4°C; P = 0.027). Out of the intervention group, 27 patients arrived in the ICU with a bladder temperature ? 36°C (90%) as compared to 14 patients (46.7%) from the control group (P < 0.001). The peripheral temperature was significantly higher in the intervention group as compared to the control group (P < 0.001). Conclusions: A full underbody forced-air warming blanket prevents postoperative hypothermia in normothermic coronary artery bypass graft surgery patients.

An evaluation of underbody forced‐air and resistive heating during hypothermic, on‐pump cardiac surgery*

We conducted a randomised controlled trial to compare the efficacy of underbody forced-air warming (Arizant Healthcare Inc, Eden Prairie, MN, USA) with an underbody resistive heating mattress (Inditherm Patient Warming System, Rotherham, UK) and passive insulation in 129 patients having hypothermic cardiac surgery with cardiopulmonary bypass. Patients were separated from cardiopulmonary bypass at a core temperature of 35 °C and external warming continued until the end of surgery. Before cardiopulmonary bypass, the temperature-vs-time slopes were significantly greater in both active warming groups than in the passive insulation group (p < 0.001 for each). However, the slopes of forced-air and resistive warming did not differ (p = 0.55). After cardiopulmonary bypass, the rate of rewarming was significantly greater with forced-air than with resistive warming or passive insulation (p < 0.001 for each), while resistive warming did not differ from passive insulation (p = 0.14). However, absolute temperature differences among the groups were small.

History of development of hypothermia in cardiac surgery and the use of cardiopulmonary bypass in the management of accidental hypothermia

History of development of hypothermia in cardiac surgery and the use of cardiopulmonary bypass in the management of accidental hypothermia

Pediatric Warm Open Heart Surgery and Prolonged Cross-Clamp Time

The safety of normothermic pediatric cardiac surgery remains controversial. This study evaluated the performance of normothermic cardiopulmonary bypass (CPB) associated with intermittent warm blood cardioplegia during prolonged aortic cross-clamp time (CCT). This retrospective study included 234 consecutive patients weighing less than 10 kg operated under CPB from August 2006 to November 2007. Patients were divided into two groups: group 1 contained 38 patients with CCT exceeding 90 minutes, and group 2 had 196 patients with shorter CCT. Classic factors were used to analyze outcomes, and outcomes were compared with those from the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery database. Results, expressed as values for group 1 vs those for group 2, were mortality rate, 5.3% vs 2%; length of hospital stay exceeding 21 days, 5% vs 0.5%; delayed chest closure, 21% vs 2.6%; epinephrine infusion, 45% vs 11%; organ failure, 13% vs 2%; reoperation due to bleeding, 3% vs 0.5%; heart block, 3% vs 1%; time to extubation, in hours, 64 +/- 94 vs 19 +/- 48; plasma lactate concentrations after bypass, 2.6 vs 1.9 mmol/L; length of stay in intensive care, in hours, 100 +/- 105 vs 52 +/- 48. Despite expected differences between the two groups, our results were within the range of values described in the literature. This led us to conclude that warm pediatric cardiac surgery with a long CCT is safe. A large, multicenter, randomized prospective study comparing normothermic and hypothermic pediatric cardiac surgery is underway.

Long-Term Outcome of Intracardiac Repair under Simple Deep Hypothermia

Development of cardiopulmonary bypass has contributed to pediatric cardiac surgery, but at the dawn of cardiac surgery, simple deep hypothermia was used to avoid the deleterious effect of cardiopulmonary bypass. Between 1981 and 1990, 45 patients with simple cardiac anomalies underwent definitive surgery under deep hypothermia. Age at operation was 35 days to 20 months, and body weight was 2.3 to 8.0 kg. Under morphine and ether anesthesia, a median sternotomy was performed when the esophageal temperature reached 26.3 degrees C +/- 1.3 degrees C by the application of surface cooling. At a minimum esophageal temperature of 19.6 degrees C +/- 2.3 degrees C, inflow occlusion and cold cardioplegia were applied to induce circulatory arrest for 32.4 +/- 10.2 min. Direct cardiac massage was used to restore cardiac activity during rewarming. All but one patient was in New York Heart Association functional class I postoperatively. The latest cardiothoracic ratio was 49.8% +/- 4.7%. All but 2 patients are free from medication. Five of 30 patients showed developmental delay in the long-term; 2 of these had a long circulatory arrest period, and 3 had prolonged heart failure postoperatively. The other 25 patients had excellent physiologic and mental development. The long-term outcome of perfusionless hypothermic cardiac surgery is satisfactory when applied appropriately.

Perioperative Neuronal Injury After Deep Hypothermic Circulatory Arrest and Cardiac Surgery

Perioperative Neuronal Injury After Deep Hypothermic Circulatory Arrest and Cardiac Surgery

Large bolus dose vs. continuous infusion of cisatracurium during hypothermic cardiopulmonary bypass surgery

Background and objective: We investigated whether a high bolus dose of cisatracurium (8× ED95) given at induction can provide muscle relaxation for the major part of a cardiac procedure with hypothermic cardiopulmonary bypass, avoid important postoperative residual curarization and cause no waste of product. Methods: Twenty patients were randomly assigned either to Group 1 (n = 10) or Group 2 (n = 10). Those in Group 1 were given cisatracurium in a high bolus dose (0.4 mg kg−1). Those in Group 2 received cisatracurium 0.1mg kg−1 at induction followed after 30 min by a continuous infusion of cisatracurium. As an escape medication in case of patient movement, a bolus dose of cisatracurium 0.03 mg kg−1 was given. Results: In Group 1 (large cisatracurium bolus dose), the clinical duration of effect (until T1/T0 = 25%) was 110 min. Six of 10 patients in Group 1 required additional boluses of cisatracurium intraoperatively. Four of these six had received an additional bolus near the end of surgery and had a train-of-four (TOF) ratio = 0 at the end. The other four patients in Group 1 had a final TOF ratio >0.9. In Group 2 (continuous cisatracurium infusion), only two patients had a TOF ratio >0.9 at the end of surgery, no patient moved and none received additional boluses. The total amount of cisatracurium used in the bolus and infusion Groups was 34.5 ± 7.8 and 21.3 ± 5.7 mg, respectively (P = 0.0004). Conclusions: For continued neuromuscular block during hypothermic cardiac surgery, a high bolus dose of cisatracurium appears to be safe, although it is not an alternative to a continuous infusion, as its neuromuscular blockade does not cover the intraoperative period and a high incidence of movements occurs. In the patients who received a high bolus dose of cisatracurium, postoperative residual curarization appeared after additional boluses had been given. The consumption of cisatracurium by high bolus was significantly greater than with continuous infusion.

Large bolus dose vs. continuous infusion of cisatracurium during hypothermic cardiopulmonary bypass surgery

We investigated whether a high bolus dose of cisatracurium (8x ED95) given at induction can provide muscle relaxation for the major part of a cardiac procedure with hypothermic cardiopulmonary bypass, avoid important postoperative residual curarization and cause no waste of product. Twenty patients were randomly assigned either to Group 1 (n = 10) or Group 2 (n = 10). Those in Group 1 were given cisatracurium in a high bolus dose (0.4 mg kg(-1)). Those in Group 2 received cisatracurium 0.1 mg kg(-1) at induction followed after 30 min by a continuous infusion of cisatracurium. As an escape medication in case of patient movement, a bolus dose of cisatracurium 0.03 mg kg(-1) was given. In Group 1 (large cisatracurium bolus dose), the clinical duration of effect (until T1/T0 = 25%) was 110 min. Six of 10 patients in Group 1 required additional boluses of cisatracurium intraoperatively. Four of these six had received an additional bolus near the end of surgery and had a train-of-four (TOF) ratio = 0 at the end. The other four patients in Group 1 had a final TOF ratio >0.9. In Group 2 (continuous cisatracurium infusion), only two patients had a TOF ratio >0.9 at the end of surgery, no patient moved and none received additional boluses. The total amount of cisatracurium used in the bolus and infusion Groups was 34.5 +/- 7.8 and 21.3 +/- 5.7 mg, respectively (P = 0.0004). For continued neuromuscular block during hypothermic cardiac surgery, a high bolus dose of cisatracurium appears to be safe, although it is not an alternative to a continuous infusion, as its neuromuscular blockade does not cover the intraoperative period and a high incidence of movements occurs. In the patients who received a high bolus dose of cisatracurium, postoperative residual curarization appeared after additional boluses had been given. The consumption of cisatracurium by high bolus was significantly greater than with continuous infusion.

Cardiac surgery under perfusionless hypothermia: Siberian experience.

Between January 1995 and December 1999, 942 patients (452 males and 490 females) aged 1 to 51 years underwent definitive surgery under perfusionless hypothermia for correction of congenital heart defects, predominantly uncomplicated ventricular or atrial septal defects (80%). Hypothermia of 24 degrees C to 28 degrees C was achieved in 15 to 45 minutes (mean, 25.7 +/- 1.2 minutes) by application of crushed ice over the body and head. Aortic crossclamp time ranged from 10 to 76 minutes (mean, 26.1 +/- 0.25 minutes). Cardiac restoration time ranged from 1 to 10 minutes (mean, 2.1 +/- 0.08 minutes). Eight patients (0.85%) died postoperatively: 4 from acute cardiac insufficiency, 2 as a consequence of technical faults, 1 from persistent pulmonary hypertension, and 1 had sudden cardiac arrest. None of the surviving patients showed any gross neurological deficit. Perfusionless hypothermic cardiac surgery, when applied appropriately, is safe and simple, and might still have a place in treating a selected group of patients with uncomplicated congenital heart defects.