Influence of body core temperature on blood loss and transfusion requirements during off-pump coronary artery bypass grafting: a comparison of 3 warming systems

Comparative Efficacy of Six Active Warming Systems for Intraoperative Warming in Adult Patients Undergoing Laparoscopic Surgery: A Systematic Review and Network Meta-Analysis

Intraoperative hypothermia is very common and harmful in adult patients undergoing laparoscopic surgery. A variety of active warming systems has received close attention and has been researched by related scholars. However, the relative efficacy of these systems and which active warming system is preferred for such patients remain unclear. The aim of this study was to compare and rank six active warming systems regarding intraoperative warming efficacy in adult patients undergoing laparoscopic surgery. Following the PRISMA 2020 guidelines, relevant randomized controlled trials (RCTs) on the efficacy of different active warming systems in warming adult patients undergoing laparoscopic surgery were searched from five English databases and three Chinese databases. The quality of the studies was assessed using the Cochrane Risk of Bias tool (RoB2). The outcome was the final intraoperative core temperature. We estimated direct effects by using pairwise meta-analysis, estimated relative effects and ranking with the consistency model to conduct an NetworkMeta-Analysis (NMA). We used GRADE (Grading of Recommendations Assessment, Development, and Evaluation) to assess the certainty of the evidence. Sensitivity analysis was performed to test the robustness of the results. This study is registered with PROSPERO, with number CRD42022309057. In total, 19 RCTs involving 6 active warming systems and comprising 1364 patients were included in this NMA. The NMA once again confirmed the validity of forced-air warming (FAW) systems compared with other active warming systems, and further showed that underbody FAW was associated with more remarkable warming efficacy in different types of FAW systems. NMA was used to perform an exhaustive comparison of the warming efficacy of six active warming systems and indicated that underbody FAW was most likely to be the most effective warming system in adult patients undergoing laparoscopic surgery; however, considering the sparsity of the network, our results should be cautiously interpreted. Furthermore, a large number of high-quality RCTs comparing the warming efficacy of different competitive active warming systems are needed.

Evaluation of the Temple Touch Pro™ noninvasive core-temperature monitoring system in 100 adults under general anesthesia: a prospective comparison with esophageal temperature

Perioperative hypothermia is still common and has relevant complication for the patient. An effective perioperative thermal management requires essentially an accurate method to measure core temperature. So far, only one study has investigated the new Temple Touch Pro™ (Medisim Ltd., Beit-Shemesh, Israel). during anesthesia Therefore, we assessed the agreement between the Temple Touch Pro™ thermometer (TTP) and distal esophageal temperature (T_Eso) in a second study. After approval by the local ethics committee we studied 100 adult patients undergoing surgery with general anesthesia. Before induction of anesthesia the TTP sensor unit was attached to the skin above the temporal artery. After induction of anesthesia an esophageal temperature probe was placed in the distal esophagus. Recordings started 10 min after placement of the esophageal temperature probe to allow adequate warming of the probes. Pairs of temperature values were documented in five-minute intervals until emergence of anesthesia. Accuracy of the two methods was assessed by Bland-Altman comparisons of differences with multiple measurements. Core temperatures obtained with the TTP in adults showed a mean bias of -0.04 °C with 95% limits of agreement within - 0.99 °C to + 0.91 °C compared to an esophageal temperature probe. We consider the TTP as a reasonable tool for perioperative temperature monitoring. It is not accurate enough to be used as a reference method in scientific studies, but may be a useful tool especially for conscious patients undergoing neuraxial anesthesia or regional anesthesia with sedation. Trial registration This study was registered in the German Clinical Trials Register (DRKS-ID: 00024050), day of registration 12/01/2021.

Health Technology Assessment for the Prevention of Peri-Operative Hypothermia: Evaluation of the Correct Use of Forced-Air Warming Systems in an Italian Hospital

This study investigates the implications of using a system for the maintenance of normothermia in the treatment of patients undergoing surgery, determining whether the FAW (Forced-Air Warming) systems are more effective and efficient than the non-application of appropriate protocols (No Technology). We conducted Health Technology Assessment (HTA) analysis, using both real-world data and the data derived from literature, assuming the point of view of a medium-large hospital. The literature demonstrated that Inadvertent Perioperative Hypothermia (IPH) determines adverse events, such as surgical site infection (FAW: 3% vs. No Technology: 12%), cardiac events (FAW: 3.5% vs. No Technology: 7.6%) or the need for blood transfusions (FAW: 6.2% vs. No Technology: 7.4%). The correct use of FAW allows a medium saving of 16% per patient to be achieved, compared to the non-use of devices. The Cost Effectiveness Value (CEV) is lower in the hypothesis of FAW: it enables a higher efficacy level with a contextual optimization of patients' path costs. The social cost is reduced by around 30% and the overall hospital days are reduced by between 15% and 26%. The qualitative analyses confirmed the results. In conclusion, the evidence-based information underlines the advantages of the proper use of FAW systems in the prevention of accidental peri-operative hypothermia for patients undergoing surgery.

Barriers to body temperature monitoring among prehospital personnel: a qualitative study using the modified nominal group technique

OBJECTIVES

To identify and explore barriers that healthcare professionals working as prehospital care (PHC) providers at the University Hospital of North Norway experience with temperature monitoring and discover solutions to these problems.

STUDY DESIGN

Qualitative study using the modified nominal group technique.

MATERIALS AND METHODS

14 experienced healthcare professionals working in air and ground emergency medical services were invited to the study. Initially, each participant was asked to suggest through email topics of importance regarding barriers to prehospital thermometry. Afterwards, they received a list of all disparate topics and were asked to individually rank them by importance. The top-ranked topics were discussed in a consensus meeting. The meeting was audio-recorded and a transcript was written and then analysed through an inductive thematic analysis.

RESULTS

13 participants accepted the invitation. 63 suggestions were reduced to 24 disparate topics after removal of duplicates. Twelve highly ranked topics were discussed during the consensus meeting. Thematic analysis revealed 47 codes that were grouped together into six overarching themes, of which four described challenges to monitoring and two described potential solutions: equipment dissatisfaction, little focus on patient temperature, fear of iatrogenic complications, thermometry subordinated, more focus on temperature and simplification of thermometry.

CONCLUSION

To increase the frequency of temperature measurement on correct indication, we suggest introducing PHC protocols that specify patients and conditions where an accurate temperature measurement should have high priority. Furthermore, there is a profound need for more suitable techniques for temperature monitoring in the prehospital setting.

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.

Fluid management: An update for perioperative practitioners

An interprofessional team approach is required to achieve optimum fluid balance for patients during the perioperative period. Incorrect management of fluid assessment and monitoring is associated with adverse outcomes. The scientific understanding of perioperative fluid balance has improved over recent years leading to changes in clinical practice with regard to volume and choice of intravenous fluid. It is important that perioperative practitioners have an understanding of intravenous fluid, fluid compartmentalisation, fluid mechanics and intravascular fluid control mechanisms. Optimum fluid status not only shortens hospital stay but also reduces the incidence of postoperative nausea and vomiting and complication profiles. This article aims to provide perioperative practitioners with a comprehensive overview of fluid management. It will cover important issues surrounding physiological control of fluid balance, choice of intravenous fluid therapy, methods to monitor intravascular volume and factors which influence delivery.

Intraoperative thermal insulation in off-pump coronary artery bypass grafting surgery: a prospective, double blind, randomized controlled, single-center study

Background

About 50% patients who underwent off-pump coronary artery bypass grafting (OPCAB) experienced perioperative hypothermia. Pre-warming and intraoperative infusion of amino acid injection are the most popular perioperative insulation measures in recent years, but neither of them can completely prevent intraoperative hypothermia. The objective is to investigate the effect of preoperative warming and/or intraoperative infusion of amino acid injection on body temperature in patients undergoing OPCAB.

Methods

A prospective, double blind, randomized controlled, single-center study. Seventy-two patients were randomly divided into 4 groups: control group, pre-warming group, amino-acid group and multi-mode group. Pre-warming and multi-mode group were pre-heated with warming blankets and forced-air warming system before induction. After that, amino-acid and multi-mode group were infused with 18-amino acid solution. The perioperative temperature and complications were monitored.

Results

The temperature of control and amino-acid group decreased significantly, but amino-acid group recovered to preoperative level faster. The temperature of pre-warming group was stable, and that in multi-mode group increased at 60 min after the start of surgery. There was a significant difference in temperature at each time, and no difference in the incidence of complications between the groups.

Conclusions

Preoperative warming and/or intraoperative infusion of amino acid injection can effectively reduce hypothermia in OPCAB surgery. Pre-warming before anesthesia is more effective, and the combination of the two methods has the best effect.

Influence of Body Temperature on Bispectral Index-Guided Anesthetic Management in Off-Pump Coronary Artery Bypass Grafting

Background Perioperative hypothermia is not uncommon in surgical patients due to anesthetic-induced inhibition of thermoregulatory mechanisms and exposure of patients to cold environment in the operating rooms. Core temperature reduction up to 35°C is often seen in off-pump coronary artery bypass graft (OP-CABG) surgery. Anesthetic depth can be monitored by using bispectral (BIS) index. The present study was performed to evaluate the influence of mild hypothermia on the anesthetic depth using BIS monitoring and correlation of BIS with end-tidal anesthetic concentration at varying temperatures during OP-CABG.

Materials and Methods In a prospective observational study design in a tertiary care teaching hospital, patients who underwent elective OP-CABG under endotracheal general anesthesia, were included in the study. Standard technique of anesthesia was followed. BIS, nasopharyngeal temperature, and end-tidal anesthetic concentration of inhaled isoflurane was recorded every 10 minutes. The BIS was adjusted to between 45 and 50 during surgery.

Results There were 40 patients who underwent OP-CABG during the study period. The mean age was 51.2 ± 8.7 years, mean body mass index 29.8 ± 2.2, and mean left ventricular ejection fraction was 55.4 ± 4.2%. Anesthetic requirement as guided by BIS between 45 and 50 correlated linearly with core body temperature (r = 0.999; p < 0.001). The mean decrease in the body temperature at the end of 300 minutes was 2.2°C with a mean decrease in end-tidal anesthetic concentration of 0.29%. The reduction in end-tidal anesthetic concentration per degree decrease in temperature was 0.13%. None of the patients reported intraoperative recall.

Conclusion In this study, BIS monitoring was used to guide the delivery concentration of inhaled anesthetic using a targeted range of 45 to 50. BIS monitoring allowed the appropriate reduction of anesthetic dosing requirements in patients undergoing OP-CABG without risk of awareness. There was a significant reduction in anesthetic requirements associated with reduction of core temperature. The routine use of BIS is recommended in OP-CABG to titrate anesthetic requirement during occurrence of hypothermia and facilitate fast-track anesthesia in this patient population.

Effect of hypothermia on haemostasis and bleeding risk: a narrative review

It must be remembered that clinically important haemostasis occurs in vivo and not in a tube, and that variables such as the number of bleeding events and bleeding volume are more robust measures of bleeding risk than the results of analyses.

In this narrative review, we highlight trauma, surgery, and mild induced hypothermia as three clinically important situations in which the effects of hypothermia on haemostasis are important. In observational studies of trauma, hypothermia (body temperature <35°C) has demonstrated an association with mortality and morbidity, perhaps owing to its effect on haemostatic functions. Randomised trials have shown that hypothermia causes increased bleeding during surgery. Although causality between hypothermia and bleeding risk has not been well established, there is a clear association between hypothermia and negative outcomes in connection with trauma, surgery, and accidental hypothermia; thus, it is crucial to rewarm patients in these clinical situations without delay. Mild induced hypothermia to ≥33°C for 24 hours does not seem to be associated with either decreased total haemostasis or increased bleeding risk.

Comparing Forced-Air to Resistive-Polymer Warming for Perioperative Temperature Management: A Retrospective Study

PURPOSE

Compare perioperative temperature management between forced-air warming (FAW) and resistive-polymer heating blankets (RHBs).

DESIGN

A retrospective, quasi-experimental study.

METHODS

Retrospective data analysis of nonspine orthopedic cases (N = 426) over a one-year period including FAW (n = 119) and RHBs (n = 307).

FINDINGS

FAW was associated with a significantly higher final intraoperative temperature (P = .001, d = 0.46) than the RHB. The incidence of hypothermia was not found to be significantly different at the end (P = .102) or anytime throughout surgery (P = .270). Of all patients who started hypothermic, the FAW group had a lower incidence of hypothermia at the end of surgery (P = .023).

CONCLUSIONS

FAW was associated with higher final temperatures and a greater number of normothermic patients than RHBs. However, no causal relationship between a warming device and hypothermia incidence should be assumed.

Clinical practice guideline. Unintentional perioperative hypothermia

The importance of the safety of our patients in the surgical theatre, has driven many projects. The majority of them aimed at better control and clinical performance; mainly of the variables that intervene or modulate the results of surgical procedures, and have a direct relationship with them. The Spanish Society of Anesthesiology, Critical Care and Therapeutic Pain (SEDAR), maintains a constant concern for a variable that clearly determines the outcomes of our clinical processes, "unintentional hypothermia" that develops in all patients undergoing an anesthetic or surgical procedure. SEDAR has promoted, in collaboration with other scientific Societies and patient Associations, the elaboration of this clinical practice guideline, which aims to answer clinical questions not yet resolved and for which, up to now, there are no documents based in the best scientific evidence available. With GRADE methodology and technical assistance from the Ibero-American Cochrane Collaboration office, this clinical practice guideline presents three recommendations (weak in favor) for active heating methods for the prevention of hypothermia (skin, fluid or gas); three for the prioritization of strategies for the prevention of hypothermia (too weak in favor and one strongly in favor); two of preheating strategies prior to anesthetic induction (both weak in favor); and two for research.

Intraoperative Hypothermia is Common, but not Associated With Blood Loss or Transfusion in Pediatric Posterior Spinal Fusion

BACKGROUND

Intraoperative hypothermia may be associated with increased blood loss due to the effects of temperature on clotting but this has not been evaluated in the setting of pediatric posterior spinal fusion (PSF). The purpose of this study was to determine if a correlation exists between intraoperative hypothermia and estimated blood loss (EBL) or transfusion requirements in pediatric patients undergoing PSF.

METHODS

A retrospective review of consecutive patients undergoing PSF for scoliosis at a single institution between 6/2004 and 3/2012 was performed. Exclusion criteria were fewer than 10 levels fused, anterior spinal fusion, and patients below 9 years old at time of surgery. Temperature was measured every 15 seconds using esophageal temperature probe. Input variable of hypothermia was analyzed as a binary variable Tmin ≤35°C at any point during anesthesia and as integrated temperature area under the curve (TAUC).

RESULTS

A total of 510 with an average age of 14.6 years (range, 9.0 to 24.3 y) met inclusion criteria. Totally, 56% (287/510) had idiopathic scoliosis (IS) and 44% (223/510) were non-IS. Hypothermia (Tmin≤35°C) was experienced by 45% (230/510) of all patients [48% (137/287) of IS; 42% (93/223) of non-IS]. A total of 63% (323/510) of patients were transfused with packed red blood cells (PRBC) [49% (141/287) of IS patients; 82% (182/223) of non-IS patients]. There was no correlation between Tmin≤35°C and transfusion of PRBC in all included patients (P=0.49); (IS patients P=0.45, non-IS patients P=0.61). There was no significant difference in EBL between patients who experienced hypothermia and those who did not (P=0.33; IS patients P=0.21, non-IS patients P=0.87). There was no significant correlation between TAUC and transfusion of PRBC for all patients (P=0.35), IS patients (P=0.26) and non-IS patients (P=0.54) or between TAUC and EBL (P=0.80); (IS patients P=0.57. non-IS patients P=0.62).

CONCLUSIONS

There was no significant correlation between intraoperative hypothermia and EBL or transfusion of PRBC in pediatric patients undergoing PSF.

LEVEL OF EVIDENCE

Level III.

Comparison of forced-air and water-circulating warming for prevention of hypothermia during transcatheter aortic valve replacement

Introduction

Transcatheter Aortic Valve Replacement (TAVR) procedures at our institution were complicated by perioperative hypothermia despite use of the standard of care forced-air convective warming device (the BairHugger, Augustine Medical Inc, Eden Prairie, MN, USA). To remedy this problem, we initiated a quality improvement process that investigated the use of a conductive warm water-circulating device (the Allon ThermoWrap, Menen Medical Corporation, Trevose, PA, USA), and hypothesized that it would decrease the incidence of perioperative hypothermia.

Methods

We compared two different intraoperative warming devices using a historic control. We retrospectively reviewed intraoperative records of 80 TAVRs between 6/2013 and 6/2015, 46 and 34 of which were done with the forced-air and water-circulating devices, respectively. Continuous temperature data obtained from pulmonary artery catheter, temperature upon arrival to cardiothoracic ICU (CTU), age, BSA, height, and BMI were compared.

Results

Patients warmed with both devices were similar in terms of demographic characteristics. First recorded intraoperative temperature (mean 36.26 ± SD 0.61 vs. 35.95 ± 0.46°C, p = 0.02), lowest intraoperative temperature (36.01 ± 0.58 vs. 34.89 ± 0.76°C, p<0.001), temperature at the end of the procedure (36.47 ± 0.51 vs. 35.17 ± 0.75°C, p<0.001), and temperature upon arrival to the CTU (36.35 ± 0.44 vs. 35.07 ± 0.78°C, p<0.001) were significantly higher in the water-circulating group as compared to the forced-air group.

Conclusion

A quality improvement process led to selection of a new warming device that virtually eliminated perioperative hypothermia at our institution. Patients warmed with the new device were significantly less likely to experience intraoperative hypothermia and were significantly more likely to be normothermic upon arrival to the CTU.

Active body surface warming systems for preventing complications caused by inadvertent perioperative hypothermia in adults

BACKGROUND

Inadvertent perioperative hypothermia is a phenomenon that can occur as a result of the suppression of the central mechanisms of temperature regulation due to anaesthesia, and of prolonged exposure of large surfaces of skin to cold temperatures in operating rooms. Inadvertent perioperative hypothermia has been associated with clinical complications such as surgical site infection and wound-healing delay, increased bleeding or cardiovascular events. One of the most frequently used techniques to prevent inadvertent perioperative hypothermia is active body surface warming systems (ABSW), which generate heat mechanically (heating of air, water or gels) that is transferred to the patient via skin contact.

OBJECTIVES

To assess the effectiveness of pre- or intraoperative active body surface warming systems (ABSW), or both, to prevent perioperative complications from unintended hypothermia during surgery in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 9, 2015); MEDLINE (PubMed) (1964 to October 2015), EMBASE (Ovid) (1980 to October 2015), and CINAHL (Ovid) (1982 to October 2015).

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared an ABSW system aimed at maintaining normothermia perioperatively against a control or against any other ABSW system. Eligible studies also had to include relevant clinical outcomes other than measuring temperature alone.

DATA COLLECTION AND ANALYSIS

Several authors, by pairs, screened references and determined eligibility, extracted data, and assessed risks of bias. We resolved disagreements by discussion and consensus, with the collaboration of a third author.

MAIN RESULTS

We included 67 trials with 5438 participants that comprised 79 comparisons. Forty-five RCTs compared ABSW versus control, whereas 18 compared two different types of ABSW, and 10 compared two different techniques to administer the same type of ABSW. Forced-air warming (FAW) was by far the most studied intervention.Trials varied widely regarding whether the interventions were applied alone or in combination with other active (based on a different mechanism of heat transfer) and/or passive methods of maintaining normothermia. The type of participants and surgical interventions, as well as anaesthesia management, co-interventions and the timing of outcome measurement, also varied widely. The risk of bias of included studies was largely unclear due to limitations in the reports. Most studies were open-label, due to the nature of the intervention and the fact that temperature was usually the principal outcome. Nevertheless, given that outcome measurement could have been conducted in a blinded manner, we rated the risk of detection and performance bias as high.The comparison of ABSW versus control showed a reduction in the rate of surgical site infection (risk ratio (RR) 0.36, 95% confidence interval (CI) 0.20 to 0.66; 3 RCTs, 589 participants, low-quality evidence). Only one study at low risk of bias observed a beneficial effect with forced-air warming on major cardiovascular complications (RR 0.22, 95% CI 0.05 to 1.00; 1 RCT with 12 events, 300 participants, low-quality evidence) in people at high cardiovascular risk. We found no beneficial effect for mortality. ABSW also reduced blood loss during surgery but the magnitude of this effect seems to be irrelevant (MD -46.17 mL, 95% CI -82.74 to -9.59; I² = 78%; 20 studies, 1372 participants). The same conclusion applies to total fluids infused during surgery (MD -144.49 mL, 95% CI -221.57 to -67.40; I² = 73%; 24 studies, 1491 participants). These effects did not translate into a significant reduction in the number of participants being transfused or the average amount of blood transfused. ABSW was associated with a reduction in shivering (RR 0.39, 95% CI 0.28 to 0.54; 29 studies, 1922 participants) and in thermal comfort (standardized mean difference (SMD) 0.76, 95% CI 0.29 to 1.24; I² = 77%, 4 trials, 364 participants).For the comparison between different types of ABSW system or modes of administration of a particular type of ABSW, we found no evidence for the superiority of any system in terms of clinical outcomes, except for extending systemic warming to the preoperative period in participants undergoing major abdominal surgery (one study at low risk of bias).There were limited data on adverse effects (the most relevant being thermal burns). While some trials included a narrative report mentioning that no adverse effects were observed, the majority made no reference to it. Nothing so far suggests that ABSW involves a significant risk to patients.

AUTHORS' CONCLUSIONS

Forced-air warming seems to have a beneficial effect in terms of a lower rate of surgical site infection and complications, at least in those undergoing abdominal surgery, compared to not applying any active warming system. It also has a beneficial effect on major cardiovascular complications in people with substantial cardiovascular disease, although the evidence is limited to one study. It also improves patient's comfort, although we found high heterogeneity among trials. While the effect on blood loss is statistically significant, this difference does not translate to a significant reduction in transfusions. Again, we noted high heterogeneity among trials for this outcome. The clinical relevance of blood loss reduction is therefore questionable. The evidence for other types of ABSW is scant, although there is some evidence of a beneficial effect in the same direction on chills/shivering with electric or resistive-based heating systems. Some evidence suggests that extending systemic warming to the preoperative period could be more beneficial than limiting it only to during surgery. Nothing suggests that ABSW systems pose a significant risk to patients.The difficulty in observing a clinically-relevant beneficial effect with ABSW in outcomes other than temperature may be explained by the fact that many studies applied concomitant procedures that are routinely in place as co-interventions to prevent hypothermia, whether passive or active warming systems based in other physiological mechanisms (e.g. irrigation fluid or gas warming), as well as a stricter control of temperature in the context of the study compared with usual practice. These may have had a beneficial effect on the participants in the control group, leading to an underestimation of the net benefit of ABSW.

Cost of Bleeding in Trauma and Complex Cardiac Surgery

PURPOSE

Trauma and complex cardiac surgery are associated with a high risk of bleeding complications. The difference in costs between patients who require bleeding control measures and those who do not is poorly understood. Our goal was to assess the cost of care and outcomes for patients in these settings.

METHODS

Patients >18 years of age, who were discharged between January 2010 and December 2012, were retrospectively identified in the Premier Hospital Database based on International Classification of Disease, Ninth Revision codes. These patients were categorized as having received blood products ("bleeding patients") or not ("nonbleeding patients"). Patients with costs and length of stay (LOS) of zero were excluded. Differences in treatment costs and outcomes were assessed using univariate analysis and multivariate modeling.

FINDINGS

Bleeding trauma patients (n = 8800) had a 150% higher total cost of care (P < 0.001; 146% after excluding costs of agents used for bleeding control, P < 0.001), an 81.3% longer hospital LOS (P < 0.001), and a 65.2% longer intensive care unit (ICU) LOS (P < 0.001) than nonbleeding patients (n = 53,727). Bleeding complex cardiac surgery patients (n = 82,832) had a 133.2% higher total cost of care (P < 0.001; 128.7% after excluding costs of agents used for bleeding control, P < 0.001), a 155.6% longer hospital LOS (P < 0.001), and an 89.3% longer ICU LOS (P < 0.001) than nonbleeding patients (n = 380,902).

IMPLICATIONS

Trauma and cardiac surgery patients who experienced bleeding and received allogeneic blood product transfusions had significantly worse outcomes, including longer LOS, greater inpatient mortality, and higher costs of care (even when excluding costs of agents used for bleeding control) than those who did not.

The effectiveness of low-dose desmopressin in improving hypothermia-induced impairment of primary haemostasis under influence of aspirin - a randomized controlled trial

Background

Mild hypothermia (34–35 °C) increases perioperative blood loss. Our previous studies showed that desmopressin could have in vitro beneficial effects on hypothermia-induced primary haemostasis impairment. In this study, we investigate the in vitro effects of desmopressin on hypothermia-induced primary haemostasis impairment under the influence of aspirin in healthy volunteers.

Methods

Sixty healthy volunteers were randomly allocated to taking aspirin 100 mg or placebo for three days. On the sixth day blood samples were taken before and after the injection of desmopressin (1.5 microgram or 5 microgram) or normal saline subcutaneously. Measurements including Platelet Function Analyzer (PFA-100®) closure times, plasma von Willebrand Factor antigen, haemoglobin and platelet levels were made at 32 °C and 37 °C respectively.

Results

Collagen/epinephrine closure time (EPICT) was significantly prolonged by 21.13 % (95 %CI 2.34–39.74 %, p = 0.021) in aspirin group at 37 °C. While hypothermia alone prolonged both collagen/adenosine diphosphate (ADPCT) and EPICT by 17.63 % (95 %CI 13.5–20.85 %, p < 0.001) and 8.0 % (95 %CI 6.38–10.04 %, p = 0.024) respectively, addition of aspirin only further prolonged EPICT by 19.9 % (95 %CI 3.32–36.49 %, p = 0.013). In aspirin group, desmopressin 1.5 microgram and 5 microgram significantly reduced ADPCT to below baseline levels at 37 °C (p = 0.025 and <0.001 respectively), whereas reduction in EPICT was seen with desmopressin 5 microgram (p =0.008). The effect was less pronounced at 32 °C, with a significant reduction in EPICT obtained with a dosage of 5 microgram only (p = 0.011).

Conclusion

It was shown that aspirin could further potentiate the hypothermia-induced closure time prolongations. Low dose desmopressin (1.5 microgram) reduced PFA-100® closure times towards baseline. A higher dosage (5 microgram) further reduced the closure times below baseline. Therefore low dose desmopressin (1.5 microgram) might have the potential to correct hypothermia-induced primary haemostasis impairment under the influence of aspirin during the perioperative period.

Trial registration

ClinicalTrials.gov: NCT01382134

The Effect of Circadian Melatonin Levels on Inflammation and Neurocognitive Functions Following Coronary Bypass Surgery

PURPOSE

In this study, the relationship between the plasma levels of melatonin and intercellular adhesion molecule-1 (ICAM-1), which plays role in several intercellular interactions including inflammatory and immune responses, and early neurocognitive functions associated with ischaemia-reperfusion injury during open heart surgery is examined.

METHODS

Forty patients who were to undergo elective coronary artery bypass grafting (CABG) were divided into two groups, those who underwent their operations at 8 AM (group I; n = 20) and those who underwent their operations at 1 PM (group II; n = 20). Blood samples were collected prior to surgery (S1), when the aortic cross clamp was removed (S2) and 4 (S3) and 24 h after the surgery (S4). Neuropsychiatric assessment was conducted one day before and seven days after surgery.

RESULTS

Melatonin levels measured during and after surgery were also significantly higher in Group 1. ICAM-1 levels were significantly lower in Group 1 at S2 and S3. Significant deterioration was observed in postoperative neurocognitive function compared with preoperative functions in Group 2 more than Group 1.

CONCLUSION

We hypothesise that the greater preservation of neurocognitive functions in the morning patients is associated with elevated melatonin levels, which reduce the damage from ischaemia-reperfusion injury.

Management of super-refractory status epilepticus with isoflurane and hypothermia

Super-refractory status epilepticus (SRSE) is defined as status epilepticus that continues 24 h or more after the onset of anesthesia, and includes those cases in which epilepsy is recurrent upon treatment reduction. We describe the presentation and successful management of a male patient with SRSE using the inhaled anesthetic isoflurane, and mild hypothermia (HT). The potential utility of combined HT and volatile anesthesia is discussed.

Effect of piracetam on the cognitive performance of patients undergoing coronary bypass surgery: A meta-analysis

Cognitive impairments are observed in numerous patients following coronary bypass surgery, and piracetam are nootropic compounds that modulate cerebral functions by directly enhancing cognitive processes. The present meta-analysis was conducted to evaluate the protective effect of piracetam on the cognitive performance of patients undergoing coronary bypass surgery. The relevant studies were identified by searching Medline, EMBASE, PubMed and the Cochrane Library up to June 2013 and the pertinent bibliographies from the retrieved studies were reviewed. Data were selected from the studies according to predefined criteria. The meta-analysis included two randomized control trials involving 184 patients and including the Syndrom-Kurz test (SKT). Findings of the meta-analysis showed that following treatment the change from baseline observed in five SKT subtest scores, conducted with piracetam patients, indicated a significant advantage over those patients that were in the placebo group. The subtests included immediate pictured object recall, weighted mean difference (WMD)=0.91, 95% confidence interval (CI) 0.51–1.31, P<0.00001; delayed pictured object recall, WMD=0.74, 95% CI 0.19–1.28, P=0.008; delayed picture recognition, WMD=0.82, 95% CI 0.31–1.31, P=0.001; immediate word recall, WMD=0.87, 95% CI 0.47–1.28, P<0.0001; and letter interference, WMD=3.46, 95% CI −5.69 to −1.23, P=0.002. These results indicated that piracetam may have been effective in improving the short-term cognitive performance of patients undergoing coronary bypass surgery. High quality, well-controlled and longer randomized trials are required to corroborate this result.

Monitoring in the intensive care

In critical care, the monitoring is essential to the daily care of ICU patients, as the optimization of patient's hemodynamic, ventilation, temperature, nutrition, and metabolism is the key to improve patients' survival. Indeed, the decisive endpoint is the supply of oxygen to tissues according to their metabolic needs in order to fuel mitochondrial respiration and, therefore, life. In this sense, both oxygenation and perfusion must be monitored in the implementation of any resuscitation strategy. The emerging concept has been the enhancement of macrocirculation through sequential optimization of heart function and then judging the adequacy of perfusion/oxygenation on specific parameters in a strategy which was aptly coined “goal directed therapy.” On the other hand, the maintenance of normal temperature is critical and should be regularly monitored. Regarding respiratory monitoring of ventilated ICU patients, it includes serial assessment of gas exchange, of respiratory system mechanics, and of patients' readiness for liberation from invasive positive pressure ventilation. Also, the monitoring of nutritional and metabolic care should allow controlling nutrients delivery, adequation between energy needs and delivery, and blood glucose. The present paper will describe the physiological basis, interpretation of, and clinical use of the major endpoints of perfusion/oxygenation adequacy and of temperature, respiratory, nutritional, and metabolic monitorings.

Active cutaneous warming systems to prevent intraoperative hypothermia: a systematic review

This study analyzed the evidence available in the literature concerning the effectiveness of different active cutaneous warming systems to prevent intraoperative hypothermia. This is a systematic review with primary studies found in the following databases: CINAHL, EMBASE, Cochrane Register of Controlled Trials and Medline. The sample comprised 23 randomized controlled trials. There is evidence in the literature indicating that the circulating water garment system is the most effective in maintaining patient body temperature. These results can support nurses in the decision-making process concerning the implementation of effective measures to maintain normothermia, though the decision of health services concerning which system to choose should also take into account its cost-benefit status given the cost related to the acquisition of such systems.

Core temperatures during major abdominal surgery in patients warmed with new circulating-water garment, forced-air warming, or carbon-fiber resistive-heating system

PURPOSE

It has been reported that recently developed circulating-water garments transfer more heat than a forced-air warming system. The authors evaluated the hypothesis that circulating-water leg wraps combined with a water mattress better maintain intraoperative core temperature ≥36°C than either forced-air warming or carbon-fiber resistive heating during major abdominal surgery.

METHODS

Thirty-six patients undergoing open abdominal surgery were randomly assigned to warming with: (1) circulating-water leg wraps combined with a full-length circulating-water mattress set at 42°C, (2) a lower-body forced-air cover set on high (≈43°C), and (3) a carbon-fiber resistive-heating cover set at 42°C. Patients were anesthetized with general anesthesia combined with continuous epidural analgesia. The primary outcome was intraoperative tympanic-membrane temperature ≥36°C.

RESULTS

In the 2 h after anesthesia induction, core temperature decreased 1.0 ± 0.5°C in the forced-air group, 0.9 ± 0.2°C in the carbon-fiber group, and 0.4 ± 0.4°C in the circulating-water leg wraps and mattress group (P < 0.05 vs. forced-air and carbon-fiber heating). At the end of surgery, core temperature was 0.2 ± 0.7°C above preoperative values in the circulating-water group but remained 0.6 ± 0.9°C less in the forced-air and 0.6 ± 0.4°C less in the carbon-fiber groups (P < 0.05 vs. carbon fiber).

CONCLUSIONS

The combination of circulating-water leg wraps and a mattress better maintain intraoperative core temperature than did forced-air and carbon-fiber warming systems.

Intensified thermal management for patients undergoing transcatheter aortic valve implantation (TAVI)

Background

Transcatheter aortic valve implantation via the transapical approach (TAVI-TA) without cardiopulmonary bypass (CPB) is a minimally invasive alternative to open-heart valve replacement. Despite minimal exposure and extensive draping perioperative hypothermia still remains a problem.

Methods

In this observational study, we compared the effects of two methods of thermal management on the perioperative course of core temperature. The methods were standard thermal management (STM) with a circulating hot water blanket under the patient, forced-air warming with a lower body blanket and warmed infused fluids, and an intensified thermal management (ITM) with additional prewarming using forced-air in the pre-operative holding area on the awake patient.

Results

Nineteen patients received STM and 20 were treated with ITM. On ICU admission, ITM-patients had a higher core temperature (36.4 ± 0.7°C vs. 35.5 ± 0.9°C, p = 0.001), required less time to achieve normothermia (median (IQR) in min: 0 (0-15) vs. 150 (0-300), p = 0.003) and a shorter period of ventilatory support (median (IQR) in min: 0 (0-0) vs. 246 (0-451), p = 0.001).

Conclusion

ITM during TAVI-TA reduces the incidence of hypothermia and allows for faster recovery with less need of ventilatory support.

Hipotermia no período intra-operatório: é possível evitá-la?

O estudo teve como objetivo identificar as medidas adotadas para a prevenção de hipotermia no período intra-operatório. Trata-se de um estudo com delineamento de pesquisa não experimental, tipo descritivo-exploratório, prospectivo. Para tal elaborou-se um instrumento de coleta de dados, o qual foi submetido à validação aparente e de conteúdo. A amostra foi constituída de 70 pacientes. A medida mais empregada na sala de operação foi o método passivo de aquecimento cutâneo como o uso de lençol de algodão (11,4%) e o enfaixamento dos membros inferiores (14,3%). A utilização de um método ativo de aquecimento cutâneo ocorreu uma única vez (1,4%). Os resultados evidenciados demonstraram a necessidade de implementação de intervenções eficazes para a prevenção da hipotermia e o enfermeiro tem papel importante neste contexto, uma vez que a segurança do paciente e a redução de complicações decorrentes do procedimento anestésico cirúrgico são metas do cuidado de enfermagem.

Forced-air and a novel patient-warming system (vitalHEAT vH2) comparably maintain normothermia during open abdominal surgery

BACKGROUND

The vitalHEAT vH(2) (Dynatherm Medical, Inc., Fremont, California) system transfers heat through a single extremity using a combination of conductive heat (circulating warm water within soft fluid pads) with mild vacuum, which improves both vasodilation and contact between the heating element and the skin surface. We tested the hypothesis that core temperatures were not >0.5°C lower in patients warmed with the vitalHEAT system than with forced air.

METHODS

Patients having general anesthesia for open abdominal surgery were randomly assigned to the circulating-water sleeve on 1 arm (n = 37) or an upper-body forced-air warming cover (n = 34). Patients were eligible to participate when body mass index was 20 to 36 kg/m(2), age was 18 to 75 years, and ASA physical status was 1 to 3. Intraoperative distal esophageal (core) temperatures were recorded. Repeated-measures analysis and 1-tailed t tests were used to assess noninferiority of vitalHEAT to forced air using a noninferiority δ of -0.5°C.

RESULTS

Demographic and morphometric characteristics were similar, as were surgical details. Preoperative core temperatures were similar in each group. Intraoperative core temperatures were also similar with each warming system and were significantly noninferior during the first four hours of surgery. The observed difference in means was never more than about 0.2°C. After 4 hours of surgery, the average temperature was 36.3°C ± 0.6°C (mean ± sd) with the circulating-water sleeve (n = 18) and 36.4°C ± 0.5°C with forced air (n = 20), for a difference (95% confidence interval) of -0.21°C (-0.47, 0.06).

CONCLUSIONS

The 2 systems thus apparently transfer comparable amounts of heat. Both appear suitable for maintaining normothermia even during large and long operations.

A systematic review of the effectiveness of cutaneous warming systems to prevent hypothermia

AIMS

To retrieve and critique recent randomised trials of cutaneous warming systems used to prevent hypothermia in surgical patients during the intraoperative period and to identify gaps in current evidence and make recommendations for future trials.

BACKGROUND

Hypothermia affects up to 70% of anaesthetised surgical patients and is associated with several significant negative health outcomes.

DESIGN

Systematic review using integrative methods.

METHODS

We searched CINAHL, EMBASE, Cochrane Register of Controlled Trials and Medline databases (January 2000-April 2007) for recent reports on randomised controlled trials of cutaneous warming systems used with elective patients during the intraoperative period. Inclusion criteria. We included randomised control trials examining the effects of cutaneous warming systems used intraoperatively on patients aged 18 years or older undergoing non-emergency surgery. Studies published in English, Spanish or Portuguese with a comparison group that consisted of either usual care or active cutaneous warming systems without prewarming were reviewed.

RESULTS

Of 193 papers initially identified, 14 studies met the inclusion criteria. There was moderate evidence to indicate that carbon-fibre blankets and forced-air warming systems are equally effective and that circulating-water garments are most effective for maintaining normothermia during the intraoperative period. Few trials reported costs.

CONCLUSIONS

Carbon-fibre blankets and forced-air warming systems are effective and circulating-water garments may be preferable. Future research should measure the direct and indirect costs associated with competing systems.

RELEVANCE TO CLINICAL PRACTICE

Nurses can use this review to inform their selection of warming interventions in perioperative nursing practice. They can also assess other factors such as nursing workload, staff training and equipment maintenance, which should be incorporated into future research.

The role of perioperative warming in surgery: a systematic review

OBJECTIVE

The objective of this review was to systematically analyze the trials on the effectiveness of perioperative warming in surgical patients.

METHODS

A systematic review of the literature was undertaken. Clinical trials on perioperative warming were selected according to specific criteria and analyzed to generate summative data expressed as standardized mean difference (SMD).

RESULTS

Twenty-five studies encompassing 3,599 patients in various surgical disciplines were retrieved from the electronic databases. Nineteen randomized trials on 1785 patients qualified for this review. The no-warming group developed statistically significant hypothermia. In the fixed effect model, the warming group had significantly less pain and lower incidence of wound infection, compared with the no-warming group. In the random effect model, the warming group was also associated with lower risk of post-anesthetic shivering. Both in the random and the fixed effect models, the warming group was associated with significantly less blood loss. However, there was significant heterogeneity among the trials.

CONCLUSION

Perioperative warming of surgical patients is effective in reducing postoperative wound pain, wound infection and shivering. Systemic warming of the surgical patient is also associated with less perioperative blood loss through preventing hypothermia-induced coagulopathy. Perioperative warming may be given routinely to all patients of various surgical disciplines in order to counteract the consequences of hypothermia.

Thermoregulatory management for mild therapeutic hypothermia

In recent years the use of mild therapeutic hypothermia as a means of neuroprotection has become an important concept for treatment after cerebral ischemic hypoxic injury. Mild therapeutic hypothermia has been shown to improve outcome after out-of-hospital cardiac arrest, and many studies suggest a beneficial effect of mild therapeutic hypothermia on patient outcome after traumatic brain injury, cerebrovascular damage and neonatal asphyxia. This review article explores the numerous possibilities and methods for the induction of mild therapeutic hypothermia, reviews thermoregulatory management during maintenance and discusses associated risks and complications.

The effect of amino-acid infusion during off-pump coronary arterial bypass surgery on thermogenic and hormonal regulation

PURPOSE

Amino-acid (AA) infusions promote thermogenesis and prevent perioperative hypothermia, but the mechanism of action is unknown. We sought to verify the hypothesis that AA infusions stimulate the release of metabolic hormones during surgery and increase energy expenditure, resulting in thermogenesis.

METHODS

Twenty-four patients were randomly assigned to receive AA (4 kJ x kg(-1) x h(-1)) or saline, which was infused for 2 h during off-pump coronary artery bypass surgery (OPCABS). Arterial adrenaline, thyroid hormone, insulin, and leptin levels were determined at five defined times during surgery. Oxygen consumption was measured 3 h after the start of infusion.

RESULTS

AA infusion maintained the body core temperature during OPCABS. This effect was accompanied by an increase in oxygen consumption, which depended on increased heart rate. AA infusion prominently stimulated the secretion of insulin and leptin; the insulin level increased rapidly within 2 h after the start of infusion, whereas leptin levels increased gradually over a 6-h period after the start of infusion.

CONCLUSION

AA infusion significantly increased body core temperature and oxygen consumption during surgery. Given the release of insulin and leptin in response to AA infusion, it is likely that these hormonal signaling pathways may, in part, have contributed to the thermogenic response that occurred during the surgery.

Temperature monitoring and perioperative thermoregulation

Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in patients not undergoing general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients undergoing general anesthesia exceeding 30 min in duration and in patients undergoing major operations during neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature, triggering cold defenses, including arteriovenous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, with the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extent than does general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.

Transforming the surgical "time-out" into a comprehensive "preparatory pause"

We propose expansion of the standard "time-out" into a comprehensive "preparatory pause" encompassing five well-documented perioperative risk avoidance strategies: beta-adrenergic blockade, DVT prophylaxis, preoperative antibiotics, normothermia, and euglycemia. Although all members of the surgical team acknowledge the clear benefit of these five prophylactic strategies, published national compliance even in the target patient population is a disappointingly consistent 50%. We have developed and field-tested a "preparatory pause" form that we appended to our "surgical time-out." By politely challenging our surgical team as to the inclusion of these five risk avoidance strategies in 167 consecutive patients, we increased our compliance to more than 90% for each preventive measure. We have not attempted to quantify the physical and psychological benefit of complication avoidance due to the enhanced activation of these five prophylactic strategies. Using published surgical complication prevalence data, with and without these accepted risk avoidance measures, we estimate the number of complications per 100 patients avoided. Utilizing the Medicare payment schedule for each complication, we approximate the purely financial benefit of the "preparatory pause" to be $88,640 per 100 patients, or almost $900 per patient. The now standard surgical "time-out" is designed to avoid the gratifyingly uncommon problem of "wrong patient,""wrong procedure," and "wrong site." Many surgeons negotiate an entire career without stumbling over these disastrous problems. We propose expansion of the "time-out" to include five well-documented perioperative risk avoidance strategies that many of us overlook all too often.

Postoperative hypothermia and blood loss after the neonatal arterial switch procedure

BACKGROUND

Numerous studies have demonstrated that mild hypothermia helps reduce hypoxic/ischemic brain injury that may occur during neonatal cardiac procedures. However, traditional intensive care practices emphasize aggressive rewarming, and the risk of excessive bleeding that may be related to hypothermia.

METHODS

An analysis was conducted of prospectively collected temperature and blood loss data on 47 neonates (30 boys, 17 girls) with transposition of the great arteries who underwent an arterial switch operation at median age 6 days (range, 2 to 23 days) and a mean weight of 3.6 +/- 0.6 kg. Blood loss was compared between 26 patients with mean temperatures below 35.5 degrees C for first 6 hours after operation (mild hypothermia group) and 21 patients at 35.5 degrees C or higher (normothermia group). Repeated-measures analysis of variance and regression modeling were used to evaluate the association between temperature and blood loss and to detect outliers.

RESULTS

Total postoperative blood loss was 31 +/- 28 mL in the first 6 hours and 61 +/- 37 mL at 24 hours (range, 15 to 238 mL). Postoperative blood loss between two groups at 6 or 24 hours did not differ significantly. After two outliers were removed, no significant relationship remained between body temperature at 6 hours and cumulative blood loss at 24 hours.

CONCLUSIONS

Mild postoperative hypothermia does not increase blood loss in neonates after the arterial switch operation. Lack of a difference between the two groups is not likely due to the study being underpowered. We recommend avoidance of aggressive rewarming, which might exacerbate potential neurologic injury.

[Perioperative thermal management]

Perioperative hypothermia can influence clinical outcome negatively. It triples the incidence of adverse myocardial outcomes, significantly increases perioperative blood loss, significantly augments allogenic transfusion requirements, and increases the incidence of surgical wound infections. The major causes are redistribution of heat from the core of the body to the peripheral tissues and a negative heat balance. Adequate thermal management includes preoperative and intraoperative measures. Preoperative measures, e.g., prewarming, enhance heat content of the peripheral tissues, thereby reducing redistribution of heat from the core to the peripheral tissues after induction of anesthesia. Intraoperative measures are active skin surface warming of a large body surface area with conductive or convective warming systems. Intravenous fluids should be warmed when large volumes of more than 500-1000 ml/h are required. The body surfaces that cannot be actively warmed should be insulated. Airway humidification and conductive warming of the back are less efficient.

Warming of intravenous fluids prevents hypothermia during off-pump coronary artery bypass graft surgery

OBJECTIVE

Even mild perioperative hypothermia (34 degrees -36 degrees C) can cause numerous adverse outcomes, including morbid cardiac events, coagulopathy with increased blood loss, and a decreased resistance to surgical wound infection. The purpose of this study was to evaluate the effect of fluid warming on preventing hypothermia during off-pump coronary artery bypass (OPCAB) surgery.

DESIGN

A prospective randomized clinical study.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Forty patients undergoing OPCAB procedures.

INTERVENTIONS

Patients were randomized into control (n = 20) and Hotline (n = 20) groups. In the Hotline group, all intravenous fluids were warmed to 41 degrees C by using 2 Hotline (SIMS Inc, Rockland, MD) systems. All patients (control and Hotline groups) were managed with standardized institutional practice by using a combination of increased ambient operating room temperature (to 25 degrees C) and the use of a warmed water mattress (38 degrees C).

MEASUREMENTS AND MAIN RESULTS

Temperatures were recorded every hour after the induction of anesthesia at the pulmonary artery, nasopharynx, rectum, and bladder. In the Hotline group, temperatures were maintained or increased. In the control group, temperatures gradually decreased. There were no significant differences between the 2 groups in hemodynamic parameters, serum catecholamine concentrations, duration of intensive care unit stay, or duration of ward stay.

CONCLUSIONS

The results show that the warming of intravenous fluids by using the Hotline system prevents decreases in systemic temperatures during OPCAB surgery.

Piracetam Prevents Cognitive Decline in Coronary Artery Bypass: A Randomized Trial Versus Placebo

BACKGROUND

Coronary artery bypass grafting (CABG) can be associated with postoperative cognitive impairment and ischemic stroke. No effective treatment is currently available. The aim of this study was to evaluate the effectiveness of piracetam to treat the cognitive impairment after CABG in an investigator-initiated, double-blind, placebo-controlled, randomized clinical trial.

METHODS

Patients undergoing CABG (n = 98) were randomized to placebo (n = 48) or piracetam (n = 50). Study drugs were administered intravenously (150 mg/kg daily; 300 mg/kg on the day of surgery) from the day before surgery to 6 days after surgery, then orally (12 g/day) up to 6 weeks after surgery. Cognitive function was assessed before surgery (baseline) and 6 weeks after surgery (outcome) by using a battery of 12 neuropsychologic tests. The Spielberger Anxiety Inventory and the Beck Depression Inventory were also administered. The combined score derived from the standardized neuropsychologic assessments was analyzed by using an analysis of covariance with baseline and education as covariates.

RESULTS

Six weeks after surgery, the combined score indicated a statistically significant treatment effect in the per protocol population (1.848, p = 0.041) and a tendency towards statistical significance in the intent-to-treat population (1.624, p = 0.064) in the group treated with piracetam, but no statistically significant treatment effect was seen in the placebo. The state of anxiety measured by the Spielberger Anxiety Inventory was decreased in both groups (-9.27 and -6.37 in the placebo and piracetam groups, respectively).

CONCLUSIONS

Six weeks after CABG, cognition was significantly improved in patients treated with piracetam. Additional trials are required to confirm these effects.

Thermal management of the patient: where does the patient lose and/or gain temperature?

PURPOSE OF REVIEW

Anesthesia inhibits normal thermoregulatory control, leading to perioperative hypothermia or allowing therapeutic hypothermia. During the last decade many studies have shown the effects of anesthesia on thermoregulation. As a consequence many active warming and cooling devices are available to manipulate patients' core temperature. This review focuses on new findings in the field of temperature management.

RECENT FINDINGS

Thermal management of patients has improved tremendously in recent years. Many outcome studies have shown adverse effects of perioperative hypothermia, as well as beneficial effects of therapeutic hypothermia after out-of-hospital cardiac arrest and brain trauma. However, inducing hypothermia is limited by physiologic thermoregulatory responses. Small reductions in core temperature lead to vasoconstriction and shivering, effectively hindering hypothermia. Thus prevention of vasoconstriction and shivering have become major goals during induction of therapeutic hypothermia. All anesthetics, opioids and sedatives lower the vasoconstriction and shivering threshold, thus allowing hypothermia. However, these drugs have side effects, such as respiratory depression, sedation and nausea. Several drugs, alone or in combination, lower the shivering threshold while causing minimal or no side effects.

SUMMARY

Anesthesia affects thermoregulatory control and leads to perioperative hypothermia. The prevention of perioperative hypothermia improves patient's outcome. Therapeutic hypothermia can be induced and also improves outcome in certain conditions.

Off-Pump Coronary Artery Bypass Grafting: The Zurich Experience

Coronary artery bypass grafting (CABG) is the surgical procedure of choice for treatment of multi-vessel coronary artery disease. The rising risk profile of the patients requiring isolated CABG and the economic pressure have prompted us to devise new operative strategies to treat these patients. Elimination of the cardiopulmonary bypass is one possible answer to the dilemma of maintaining the quality of care and reducing the exploding costs of our health system. Therefore, we developed the off-pump coronary artery bypass grafting (OPCAB) for patients requiring isolated CABG. In our experience the key to successful OPCAB relies on the order of revascularization of the myocardial walls (anterior, inferior, lateral), use of intracoronary shunt, no-touch technique for the proximal aortic anastomosis with heart string â (Guidant, IN, USA), close collaboration with the anesthesiologists, early and aggressive administration of anti-platelet therapy, endoscopic vein harvest by perfusionists, and improved body temperature control. Following these concepts, we have been able to offer the OPCAB procedure to over 90% of our patients and to reduce perioperative morbidity and global costs.