Hypothermia during cardiac surgery

Blood versus crystalloid cardioplegia during triple valve surgery: A single center experience

BACKGROUND

The efficacy of different cardioplegia solutions on outcomes of complex cardiac operations such as triple valve surgery (TVS) is scarce. Here we compared the outcomes in TVS patients receiving either crystalloid (Bretschneider) or blood (Calafiore) cardioplegia.

METHODS

Screening of our institutional database with prospectively entered data identified 471 consecutive patients (mean age 70.3 ± 9.2 years; 50.9% male), who underwent TVS (replacement or repair of aortic, mitral and tricuspid valve) between December 1994 and January 2013. In 277 patients, cardiac arrest was induced with HTK-Bretschneider solution (HTK, n = 277, 58.8%), whereas 194 received cold blood cardioplegia (BCP) according to Calafiore (n = 194, 41.2%). Comparisons of perioperative and follow up outcomes were made between cardioplegia groups.

RESULTS

Preoperative patient characteristics and comorbidities were equally balanced between groups. 30-days mortality was similar between groups (HTK: 16.2%; BCP: 18.2%; p = 0.619). Incidence of the cumulative endpoint (30days mortality, myocardial infarction (MI), arrhythmia, low cardiac output syndrome or need for permanent pacemaker implantation) was also comparable (HTK: 47.6%; BCP: 54.8%, p = 0.149). In patients with reduced left ventricular ejection fraction (LVEF <40%), 30days mortality was higher in the HTK group (HTK 18/71 22.5%; BCP 5/50 10%; p = 0.037). Five-year survival was similar between groups (52 ± 6% for HTK and 55 ± 5% for BCP patients). In-Hospital mortality was best predicted by length of surgery and reperfusion ratio. Decreased age, shorter bypass time, preserved LVEF and concomitant surgical procedures have been found to be protective from long-term mortality.

CONCLUSIONS

Myocardial protection with HTK shows equivalent outcomes compared to BCP during TVS. Patients with reduced left ventricular function may benefit from BCP during TVS.

A comprehensive review of cerebral oximetry in cardiac surgery

BACKGROUND

Patients who undergo cardiac surgery are at increased risk of stroke, postoperative cognitive decline, and delirium. These neurocognitive complications have led to increased costs, intensive care unit stays, morbidity, and mortality. As a result, there is a significant push to mitigate any neurological complications in cardiac surgery patients. Near-infrared spectroscopy to measure regional cerebral oxygen saturations has gained consideration due to its noninvasive and user-friendly nature. Cerebral oximetry desaturations during cardiac surgery have been linked to an array of adverse clinical outcomes. However, the most effective intraoperative interventions to protect this vulnerable patient population have yet to be ascertained.

AIM OF STUDY

To provide a comprehensive summary of the intraoperative management for cerebral oximetry desaturations during cardiac surgery. The review highlights clinical outcomes from cerebral oximetry use to quantify the importance of identifying cerebral desaturations during cardiac surgery. The review then interrogates possible interventions for cerebral oximetry desaturations in an effort to determine which interventions are most efficacious and to enlighten possible areas for further research.

METHODS

A narrative review of randomized controlled trials, observational studies, and systematic reviews with metanalyses was performed through August 2021.

RESULTS

There is significant heterogeneity among patient populations for which cerebral oximetry monitoring has been studied in cardiac surgery. Further, the definition of a clinically significant cerebral desaturation and the assessment of neurocognitive outcomes varied substantially across studies. As a result, metanalysis is challenging and few conclusions can be drawn. Cerebral oximetry use during cardiac surgery has not been associated with improvements in neurocognitive outcomes, morbidity, or mortality to date. The evidence to support a particular intervention for an acute desaturation is equivocal.

CONCLUSIONS

Future research is needed to quantify a clinically significant cerebral desaturation and to determine which interventions for an acute desaturation effectively improve clinical outcomes.

Reoperation for bleeding after cardiac surgery

BACKGROUND

Postoperative cardio-surgical haemostatic management is centre-specific and experience-based, which leads to a variability in patient care. This study aimed to identify which postoperative haemostatic interventions may reduce the need for reoperation after cardiac surgery in adults.

METHODS

A retrospective case-control study in a tertiary centre. Adult, elective, primary cardiac surgical patients were selected (n = 2098); cases (n = 42) were patients who underwent reoperation within 72 h after the initial surgery. Interventions administered to control surgical bleeding were compared for the need to re-operate using multiple logistic regression.

RESULTS

Rate of cardiac surgical reoperation was 2% in the study population. Three variables were found to be associated with cardiac reoperation: preoperative administration of fresh frozen plasma (OR 5.45, CI 2.34-12.35), cumulative volume of chest tube drainage and cumulative count of packed red blood cells transfusion on ICU (OR 1.98, CI 1.56-2.51).

CONCLUSION

No significant difference among specific types of postoperative haemostatic interventions was found between patients who needed reoperation and those who did not. Perioperative transfusion of fresh frozen plasma, postoperative transfusion of packed cells and cumulative volume of chest tube drainage were associated with reoperation after cardiac surgery. These variables could help predict the need for reoperation.

Effectiveness of Mild to Moderate Hypothermic Cardiopulmonary Bypass on Early Clinical Outcomes

Background: Intraoperative hypothermia is an integral part of cardiopulmonary bypass (CPB), and a precise degree of hypothermia may improve the early clinical outcomes of cardiac surgery. Presently, there is no agreement on an accurate, advantageous temperature range for routine use in CPB. To address this issue, we conducted a retrospective observational study to compare the effects of different hypothermic temperature ranges on primary (inotropic support, blood loss, and platelet count) and secondary (ventilation support and in-hospital stay) outcomes in patients undergoing elective cardiac surgery. Methods: Data were retrieved from the medical database of the Cardiovascular Surgery Department, King Edward Medical University, Lahore-Pakistan (a tertiary care hospital), dating from February 2015 to December 2017. Patients were divided into mild (34 °C to 36 °C), intermediate (31 °C to 33 °C), or moderate (28 °C to 30 °C) hypothermic groups. Results: Out of 275 patients, 245 (89.09%) fit the inclusion criteria. The cohort with mild hypothermic CPB temperatures presented better clinical outcomes in terms of requiring less inotropic support, less blood loss, fewer blood transfusions, improved platelet counts, shorter in-hospital stays, and required less ventilation support, when compared with other hypothermic groups. Conclusions: Mild hypothermic CPB (34 °C to 36 °C) may produce better clinical outcomes for cardiac surgery and improve the quality of health of cardiac patients.

Effect of nurse-initiated forced-air warming blanket on the reduction of hypothermia complications following coronary artery bypass grafting: a randomized clinical trial

AIMS

To evaluate the effect of postoperative forced-air warming (FAW) on the incidence of excessive bleeding (ExB), arrhythmia, acute myocardial infarction (AMI), and blood product transfusion in hypothermic patients following on-pump CABG and compare temperatures associated with the use of FAW and warming with a sheet and wool blanket.

METHODS AND RESULTS

A randomized clinical trial conducted with 200 patients undergoing isolated on-pump CABG from January to November 2018. Patients were randomly assigned into an Intervention Group (IG, FAW, n = 100) and Control Group (CG, sheet and blanket, n = 100). The tympanic temperature of all patients was measured over a 24-h period. ExB was the primary outcome, while arrhythmia, AMI, and blood product transfusion were secondary outcomes. The effect of the interventions on the outcomes was investigated through using bivariate logistic regression, with a level of significance of 5%. The IG was 79% less likely to experience bleeding than the CG [odds ratio (OR) = 0.21, confidence interval (CI) 95% 0.12-0.39, P < 0.001]; the occurrence of AMI in the IG was 94% lower than that experienced by the CG (OR = 0.06, CI 95% 0.01-0.48, P < 0.001); and the IG was also 77% less likely to experience arrhythmia than the CG (OR = 0.23, CI 95% 0.12-0.47, P < 0.001); no difference was found between groups in terms of blood product transfusion (P < 0.279).

CONCLUSIONS

These findings show that FAW can be used following CABG until patients reach normothermia to avoid undesirable clinical outcomes.

TRIAL REGISTRATION

REBeC RBR-5t582g.

Challenges in Patient Blood Management for Cardiac Surgery: A Narrative Review

About 15 years ago, Patient Blood Management (PBM) emerged as a new paradigm in perioperative medicine and rapidly found support of all major medical societies and government bodies. Blood products are precious, scarce and expensive and their use is frequently associated with adverse short- and long-term outcomes. Recommendations and guidelines on the topic are published in an increasing rate. The concept aims at using an evidence-based approach to rationalize transfusion practices by optimizing the patient's red blood cell mass in the pre-, intra- and postoperative periods. However, elegant as a concept, the implementation of a PBM program on an institutional level or even in a single surgical discipline like cardiac surgery, can be easier said than done. Many barriers, such as dogmatic ideas, logistics and lack of support from the medical and administrative departments need to be overcome and each center must find solutions to their specific problems. In this paper we present a narrative overview of the challenges and updated recommendations for the implementation of a PBM program in cardiac surgery.

Anticoagulation management during pulmonary endarterectomy with cardiopulmonary bypass and deep hypothermic circulatory arrest

INTRODUCTION

Pulmonary endarterectomy requires cardiopulmonary bypass and deep hypothermic circulatory arrest, which may prolong the activated clotting time. We investigated whether activated clotting time-guided anticoagulation under these circumstances suppresses hemostatic activation.

METHODS

Individual heparin sensitivity was determined by the heparin dose-response test, and anticoagulation was monitored by the activated clotting time and heparin concentration. Perioperative hemostasis was evaluated by thromboelastometry, platelet aggregation, and several plasma coagulation markers.

RESULTS

Eighteen patients were included in this study. During cooling, tube-based activated clotting time increased from 719 (95% confidence interval = 566-872 seconds) to 1,273 (95% confidence interval = 1,136-1,410 seconds; p < 0.01) and the cartridge-based activated clotting time increased from 693 (95% confidence interval = 590-796 seconds) to 883 (95% confidence interval = 806-960 seconds; p < 0.01), while thrombin-antithrombin showed an eightfold increase. The heparin concentration showed a slightly declining trend during cardiopulmonary bypass. After protamine administration (protamine-to-heparin bolus ratio of 0.82 (0.71-0.90)), more than half of the patients showed an intrinsically activated coagulation test and intrinsically activated coagulation test without heparin effect clotting time >240 seconds. Platelet aggregation through activation of the P2Y12 (adenosine diphosphate test) and thrombin receptor (thrombin receptor activating peptide-6 test) decreased (both -33%) and PF4 levels almost doubled (from 48 (95% confidence interval = 42-53 ng/mL) to 77 (95% confidence interval = 71-82 ng/mL); p < 0.01) between weaning from cardiopulmonary bypass and 3 minutes after protamine administration.

CONCLUSION

This study shows a wide variation in individual heparin sensitivity in patients undergoing pulmonary endarterectomy with deep hypothermic circulatory arrest. Although activated clotting time-guided anticoagulation management may underestimate the level of anticoagulation and consequently result in a less profound inhibition of hemostatic activation, this study lacked power to detect adverse outcomes.

2016 survey about temperature management during extracorporeal circulation in China

Objective:

In order to assess the current status of temperature management during cardiopulmonary bypass (CPB) in China and, thereby, implement standardized management protocols, the authors carried out a national survey about institutions performing CPB.

Method:

The survey was carried out from September 2015 to February 2016 and was supported by the Chinese Society of ExtraCorporeal Circulation. A total of 114 institutions participated, accounting for 15.64% (114/729) of the total of germane Chinese institutions, whereby, 80.85% (38/47) of the institutions had an annual surgical volume of more than 1000 cases.

Results:

The most common sites of temperature measurement were nasopharyngeal (NP) (99.12%) and rectal (92.98%) while oxygenator blood temperature was less popular (28%). Rectal temperature as the core temperature was chosen by 78.95% of the institutions; 92.11% of the institutions chose nasopharyngeal temperature to represent the cerebral temperature. During deep hypothermia circulatory arrest (DHCA) when there was no cerebral perfusion, 18 to 22℃ was the most common indication of circulatory arrest. However, with cerebral perfusion, more than 40% of the institutions maintained a lowest temperature of 22 to 25℃ for adult and pediatric patients. A NP temperature of 36 to 37℃ was chosen by 70.18% of the institutions while 81.79% chose a rectal temperature of 35 to 36.5℃ as the indication to wean from CPB. The majority of the institutions chose a difference of 10℃ between the water tank and core temperatures as the temperature gradient during rewarming. Auxiliary heat preservation techniques and equipment were used in 91.23% of the institutions, whereas 35.58% of them would lower the indications to wean from CPB.

Conclusions:

This survey accurately reflects the current situation of temperature management during CPB in institutions with an annual surgical volume of >500 cases, but has, hereby, failed to properly represent the institutions with a lower annual surgical volume.

Sympathetic control of reflex cutaneous vasoconstriction in human aging

This Synthesis highlights a series of recent studies that has systematically interrogated age-related deficits in cold-induced skin vasoconstriction. In response to cold stress, a reflex increase in sympathetic nervous system activity mediates reductions in skin blood flow. Reflex vasoconstriction during cold exposure is markedly impaired in aged skin, contributing to the relative inability of healthy older adults to maintain core temperature during mild cold stress in the absence of appropriate behavioral thermoregulation. This compromised reflex cutaneous vasoconstriction in healthy aging can occur as a result of functional deficits at multiple points along the efferent sympathetic reflex axis, including blunted sympathetic outflow directed to the skin vasculature, reduced presynaptic neurotransmitter synthesis and/or release, and altered end-organ responsiveness at several loci, in addition to potential alterations in afferent thermoreceptor function. Arguments have been made that the relative inability of aged skin to appropriately constrict is due to the aging cutaneous arterioles themselves, whereas other data point to the neural circuitry controlling those vessels. The argument presented herein provides strong evidence for impaired efferent sympathetic control of the peripheral cutaneous vasculature during whole body cold exposure as the primary mechanism responsible for attenuated vasoconstriction.

Excessive bleeding predictors after cardiac surgery in adults: integrative review

AIMS AND OBJECTIVES

To integrate literature data on the predictors of excessive bleeding after cardiac surgery in adults.

BACKGROUND

Perioperative nursing care requires awareness of the risk factors for excessive bleeding after cardiac surgery to assure vigilance prioritising and early correction of those that are modifiable.

DESIGN

Integrative literature review.

METHODS

Articles were searched in seven databases. Seventeen studies investigating predictive factors for excessive bleeding after open-heart surgery from 2004-2014 were included.

RESULTS

Predictors of excessive bleeding after cardiac surgery were: Patient-related: male gender, higher preoperative haemoglobin levels, lower body mass index, diabetes mellitus, impaired left ventricular function, lower amount of prebypass thrombin generation, lower preoperative platelet counts, decreased preoperative platelet aggregation, preoperative platelet inhibition level >20%, preoperative thrombocytopenia and lower preoperative fibrinogen concentration. Procedure-related: the operating surgeon, coronary artery bypass surgery with three or more bypasses, use of the internal mammary artery, duration of surgery, increased cross-clamp time, increased cardiopulmonary bypass time, lower intraoperative core body temperature and bypass-induced haemostatic disorders. Postoperative: fibrinogen levels and metabolic acidosis.

CONCLUSIONS

Patient-related, procedure-related and postoperative predictors of excessive bleeding after cardiac surgery were identified.

RELEVANCE TO CLINICAL PRACTICE

The predictors summarised in this review can be used for risk stratification of excessive bleeding after cardiac surgery. Assessment, documentation and case reporting can be guided by awareness of these factors, so that postoperative vigilance can be prioritised. Timely identification and correction of the modifiable factors can be facilitated.

A comprehensive literature review on hypothermia and early extubation following coronary artery bypass surgery

PURPOSE

The purpose of this study was to comprehensively review the literature addressing the physiological effects of hypothermia and its association with the appropriate core body temperature for extubation following coronary artery bypass surgery.

METHODS

The electronic databases MEDLINE, CINAHL and Web of Science via OVID were used to identify studies for the literature review. Search words used included 'core temperature', 'arrhythmia', 'cardiac', 'cardiac surgery', 'hypothermia', 'extubation', 'temperature', 'rewarming', and 'shivering'.

RESULTS

The literature search yielded 55 articles that met our inclusion criteria. No studies specifically identified the benefit of extubation at 36.5 ° C. Although temperatures varied, arrhythmias resulting from hypothermia were not reported until core body temperature dropped below 33 ° C.

CONCLUSION

This comprehensive literature review suggests extubation at lower temperatures (between 34 ° C and 36 ° C) may be viable if shivering and other factors known to contribute to myocardial stress can be controlled. These findings offer the possibility of earlier extubation which may promote beneficial health outcomes.

Low cardiac output as physiological phenomenon in hibernating, free-ranging Scandinavian brown bears (Ursus arctos) - an observational study

BACKGROUND

Despite 5-7 months of physical inactivity during hibernation, brown bears (Ursus arctos) are able to cope with physiological conditions that would be detrimental to humans. During hibernation, the tissue metabolic demands fall to 25% of the active state. Our objective was to assess cardiac function associated with metabolic depression in the hibernating vs. active states in free-ranging Scandinavian brown bears.

METHODS

We performed echocardiography on seven free-ranging brown bears in Dalarna, Sweden, anesthetized with medetomidine-zolazepam-tiletamine-ketamine during winter hibernation in February 2013 and with medetomidine-zolazepam-tiletamine during active state in June 2013. We measured cardiac output noninvasively using estimates of hemodynamics obtained by pulsed wave Doppler echocardiography and 2D imaging. Comparisons were made using paired T-tests.

RESULTS

During hibernation, all hemodynamic indices were significantly decreased (hibernating vs. active state): mean heart rate was 26.0 (standard deviation (SD): 5.6) beats per min vs. 75.0 (SD: 17.1) per min (P=0.002), mean stroke volume 32.3 (SD: 5.2) ml vs. 47.1 (SD: 7.9) ml (P=0.008), mean cardiac output 0.86 (SD: 0.31) l/min vs. 3.54 (SD: 1.04) l/min (P=0.003), and mean cardiac index 0.63 (SD: 0.21) l/min/kg vs. 2.45 (SD: 0.52) l/min/ m2 (P<0.001). Spontaneous echo contrast was present in all cardiac chambers in all seven bears during hibernation, despite the absence of atrial arrhythmias and valvular disease.

CONCLUSION

Free-ranging brown bears demonstrate hemodynamics comparable to humans during active state, whereas during hibernation, we documented extremely low-flow hemodynamics. Understanding these physiological changes in bears may help to gain insight into the mechanisms of cardiogenic shock and heart failure in humans.

Temperature control can abolish anesthesia-induced tau hyperphosphorylation and partly reverse anesthesia-induced cognitive impairment in old mice

AIMS

Anesthesia is related to cognitive impairment and the risk for Alzheimer's disease. Hypothermia during anesthesia can lead to abnormal hyperphosphorylation of tau, which has been speculated to be involved in anesthesia-induced cognitive impairment. The aim of this study was to investigate whether maintenance of the tau phosphorylation level by body temperature control during anesthesia could reverse the cognitive dysfunction in C57BL/6 mice.

METHODS

Eighteen-month-old mice were repeatedly anesthetized during a 2-week period with or without maintenance of body temperature, control mice were treated with normal saline instead of anesthetics. Tau phosphorylation level in mice brain was detected on western blot, and cognitive performance was measured using the Morris water maze (MWM).

RESULTS

After anesthesia-induced hypothermia in old mice, tau was hyperphosphorylated and the cognitive performance, measured on MWM, was impaired. When body temperature was controlled during anesthesia, however, the tau hyperphosphorylation was completely avoided, and there was partial recovery in cognitive impairment measured on the MWM.

CONCLUSION

Hyperphosphorylation of tau in the brain after anesthesia is an important event, and it might be, although not solely, responsible for postoperative cognitive decline.

Fibrinogen concentrate reduces intraoperative bleeding when used as first-line hemostatic therapy during major aortic replacement surgery: results from a randomized, placebo-controlled trial

OBJECTIVES

We assessed whether fibrinogen concentrate as targeted first-line hemostatic therapy was more effective than placebo or a standardized transfusion algorithm in controlling coagulopathic bleeding in patients undergoing major aortic surgery.

METHODS

In this single-center, prospective, double-blind study, adults undergoing elective thoracic or thoracoabdominal aortic replacement surgery involving cardiopulmonary bypass were randomized to intraoperative fibrinogen concentrate (n = 29) or placebo (n = 32). Study medication was given if patients had clinically relevant coagulopathic bleeding, measured by 5-minute bleeding mass, after cardiopulmonary bypass removal, protamine administration, and surgical hemostasis. Fibrinogen concentrate dosing was individualized using the thromboelastometric FIBTEM test. If bleeding continued, a standardized transfusion algorithm was followed. In the placebo group, all 32 patients received 1 transfusion cycle of fresh-frozen plasma/platelets, and 30 patients required a second transfusion cycle; none of these patients received any other procoagulant therapy. Change in bleeding rate after treatment was compared using t tests.

RESULTS

Mean change in bleeding rate after fibrinogen concentrate was -48.3 g/5 min, compared with 0.4 g/5 min after placebo (P < .001), -16.1 g/5 min after 1 transfusion cycle (fresh-frozen plasma or platelets; P = .003), and -28.0 g/5 min after 2 transfusion cycles (fresh-frozen plasma and platelets; P = .11). Reductions in bleeding rate were greater for patients with higher bleeding rates before treatment, especially with fibrinogen concentrate.

CONCLUSIONS

FIBTEM-guided intraoperative hemostatic therapy with fibrinogen concentrate is more effective than placebo in controlling coagulopathic bleeding during major aortic replacement surgery. Fibrinogen concentrate is also more effective than 1 cycle of fresh-frozen plasma/platelets and is more rapid than--and at least as effective as--2 cycles of fresh-frozen plasma/platelets.

Brain damage in cardiac surgery patients

Neuropsychological disorders and brain injury are still a serious problem in cardiac surgery patients. Owing to multifactorial mechanism of brain injury during extracorporeal circulation, the effective and safe protection is extremely difficult. Despite several studies, the ideal neuroprotective treatment has not been found. Based on literature we analysed the main mechanisms of brain injury and new methods of brain protection.

An activation-specific platelet inhibitor that can be turned on/off by medically used hypothermia

OBJECTIVE

Therapeutic hypothermia is successfully used, for example, in cardiac surgery to protect organs from ischemia. Cardiosurgical procedures, especially in combination with extracorporeal circulation, and hypothermia itself are potentially prothrombotic. Despite the obvious need, the long half-life of antiplatelet drugs and thus the risk of postoperative bleedings have restricted their use in cardiac surgery. We describe here the design and testing of a unique recombinant hypothermia-controlled antiplatelet fusion protein with the aim of providing increased safety of hypothermia, as well as cardiac surgery.

METHODS AND RESULTS

An elastin-mimetic polypeptide was fused to an activation-specific glycoprotein (GP) IIb/IIIa-blocking single-chain antibody. In silico modeling illustrated the sterical hindrance of a β-spiral conformation of elastin-mimetic polypeptide preventing the single-chain antibody from inhibiting GPIIb/IIIa at 37°C. Circular dichroism spectra demonstrated reverse temperature transition, and flow cytometry showed binding to and blocking of GPIIb/IIIa at hypothermic body temperature (≤32°C) but not at normal body temperature. In vivo thrombosis in mice was selectively inhibited at hypothermia but not at 37°C.

CONCLUSIONS

This is the first description of a broadly applicable pharmacological strategy by which the activity of a potential drug can be controlled by temperature. In particular, this drug steerability may provide substantial benefits for antiplatelet therapy.

Importance of erythropoietin in brain protection after cardiac surgery: a pilot study

BACKGROUND

Neurologic complications after cardiac operations present an important medical problem, as well as a financial burden. They increase the morbidity and hospital stays of patients who have otherwise undergone successful heart operations. The current protocols for perioperative brain protection against ischemic events are not optimal. Because of its different pleiotropic mechanisms of action, recombinant human erythropoietin might provide neuroprotection.

METHODS

In this study, we included 20 patients who were older than 18 years and required surgical revascularization of the heart with the use of the heart-lung machine. Ten patients received 3 consecutive intravenous doses (24,000 IU) of recombinant human erythropoietin (rHuEpo). Neurologic and magnetic resonance imaging (MRI) examinations were done before and in the first 5 days after surgery.

RESULTS

The erythropoietin-treated and control groups were comparable with respect to study protocol outcomes: number of coronary artery bypass grafts (3.3 and 3.2 grafts/patient, respectively), operative time (4.12 and 4.6 hours), and transfusion volume per patient (708 and 674 mL). The groups were also comparable with respect to blood pressure values at all stages of the operation. MRI scans revealed that 4 of 10 patients from the control group had fresh ischemic brain lesions after open heart surgery. None of the patients in the erythropoietin-treated group had fresh ischemic brain lesions.

CONCLUSION

Although the number of patients was small, the results regarding brain protection with rHuEpo are encouraging. rHuEpo is a promising neuroprotective agent.

Temperature management and monitoring practices during adult cardiac surgery under cardiopulmonary bypass: results of a Canadian national survey

Background: Mild to moderate systemic hypothermia is commonly used as a cerebral protective strategy during adult cardiac surgery. The benefits of this strategy for routine cardiac surgery have been questioned and the adverse effects of hyperthermia demonstrated. The purpose of the present study was to examine current temperature management and monitoring practices during adult cardiac surgery using CPB in Canada.

Methods: Web-based survey referring to adult cases undergoing cardiac surgery using CPB without the use of deep hypothermic circulatory arrest. Thirty-two questionnaires were completed, representing a 100% response rate.

Results: The usual management is to cool patients during CPB at 30 (94%) centers for low-risk (isolated primary CABG) cases and at 31 (97%) centers for high-risk (all other) cases. The average nadir temperature at the target site achieved on CPB is 34°C (range 28°C - 36°C). At 26 (81%) centers, patients are typically rewarmed to a target temperature between 36°C and 37°C before separation from CPB. Only 6 (19%) centers reported that thermistors and coupled devices used to monitor blood temperature are checked for accuracy or calibrated according to the product operating directive’s schedule or more often.

Conclusions: Contemporary management of adult cardiac surgery under CPB still involves induction of mild to moderate systemic hypothermia. Significant practice variation exists across the country with respect to target temperatures for cooling and rewarming, as well as the site for temperature monitoring. This probably reflects the lack of definitive evidence. There is a need for well-conducted clinical trials to provide more robust evidence regarding temperature management.