Optimization of cardiopulmonary bypass prime fluid to preserve microcirculatory perfusion during on-pump coronary artery bypass graft surgery: PRIME study protocol for a double-blind randomized trial.

BACKGROUND: Acute microcirculatory perfusion disturbances and organ edema are important factors leading to organ dysfunction during cardiac surgery with cardiopulmonary bypass (CPB). Priming of the CPB system with crystalloid or colloid fluids, which inevitably leads to hemodilution, could contribute to this effect. However, there is yet no optimal evidence-based strategy for this type of priming. Hence, we will investigate different priming strategies to reduce hemodilution and preserve microcirculatory perfusion. METHODS: The PRIME study is a single-center double-blind randomized trial. Patients undergoing elective coronary artery bypass graft surgery with CPB will be randomized into three groups of prime fluid strategy: (1) gelofusine with crystalloid, (2) albumin with crystalloid, or (3) crystalloid and retrograde autologous priming. We aim to include 30 patients, 10 patients in each arm. The primary outcome is the change in microcirculatory perfusion. Secondary outcomes include colloid oncotic pressure; albumin; hematocrit; electrolytes; fluid balance and requirements; transfusion rates; and endothelial-, glycocalyx-, inflammatory- and renal injury markers. Sublingual microcirculatory perfusion will be measured using non-invasive sidestream dark field video microscopy. Microcirculatory and blood measurements will be performed at five consecutive time points during surgery up to 24 h after admission to the intensive care unit. DISCUSSION: PRIME is the first study to assess the effect of different prime fluid strategies on microcirculatory perfusion in cardiac surgery with CPB. If the results suggest that a specific crystalloid or colloid prime fluid strategy better preserves microcirculatory perfusion during on-pump cardiac surgery, the current study may help to find the optimal pump priming in cardiac surgery. TRIAL REGISTRATION: ClinicalTrials.gov NCT05647057. Registered on 04/25/2023. CLINICALTRIALS: gov PRS: Record Summary NCT05647057, all items can be found in the protocol.

Effectiveness of tranexamic acid in burn patients undergoing surgery - a systematic review and meta-analysis.

BACKGROUND: Reducing blood loss during excisional surgery in burn patients remains a challenge. Tranexamic acid during surgery can potentially reduce blood loss. The use of tranexamic acid during excisional surgery in burn patients has recently been described in a review and meta-analysis. However, quality assessment on studies included was not performed and this review did not apply independent reviewers. Quality assessment of studies investigating the effectiveness of tranexamic acid in burn patients is crucial before concusions can be drawn. Therefore, we conducted a systematic review and meta-analysis of the literature investigating the effectiveness of tranexamic acid in burn patients undergoing surgery. METHODS: A systematic review and meta-analysis of the literature was conducted. The study was pre-registered in PROSPERO database (CRD42023396183). RESULTS: Five studies including two randomised controlled trials (RCTs) with a total of 303 patients were included. Risk of bias of the included studies was moderate to high. Individual results of the studies were heterogeneous. In three studies of moderate quality the administration of tranexamic acid resulted in a reduction of blood loss per unit excised area, accounting as moderate level of evidence. In two low-quality studies and one moderate quality study the administration of tranexamic acid resulted in a reduction of transfused packed Red Blood Cells (pRBC's), accounting for moderate level of evidence. Postoperative haemoglobin levels were higher after tranexamic acid administration in one study, accounting for insufficient evidence. Meta-analysis pooling overall blood loss from two separate RCTs failed to detect a statistically significant reduction. Substantial heterogeneity was observed. CONCLUSIONS: Moderate level of evidence indicates that tranexamic acid reduces blood loss per unit of excised area and transfusion of packed Red Blood Cells. Results indicate that tranexamic acid can be beneficial in burn patients undergoing surgery. More high-quality research is needed to confirm these results. Future studies should focus on the dosing of tranexamic acid, the administration approaches, and even consider combining these approaches. TRIAL REGISTRATION: PROSPERO: CRD42023396183.

Evaluation of electronic screening in the preoperative process.

STUDY OBJECTIVE: Rising patient numbers, with increasing complexity, challenge the sustainability of the current preoperative process. We evaluated whether an electronic screening application can distinguish patients that need a preoperative consultation from low-risk patients that can be first seen on the day of surgery. DESIGN: Prospective cohort study. SETTING: Preoperative clinic of a tertiary academic hospital. PATIENTS: 1395 adult patients scheduled for surgery or procedural sedation. INTERVENTIONS: We assessed a novel electronic preoperative screening application which consists of a questionnaire with a maximum of 185 questions regarding the patient's medical history and current state of health. The application provides an extensive health report, including an American Society of Anesthesiologists physical status (ASA-PS) classification and a recommendation for either consultation by an anesthesiologist at the preoperative clinic or approval for screening on the day of surgery. MEASUREMENTS: The recommendation of the electronic screening system was compared with the regular preoperative assessment using measures of diagnostic accuracy and agreement. Secondary outcomes included ASA-PS classification, patient satisfaction, and the anesthesiologists' opinion on the completeness and quality of the screening report. RESULTS: Sensitivity to detect patients who needed additional consultation was 97.5% (95%CI 91.2-99.7) and the negative likelihood ratio was 0.08 (95%CI 0.02-0.32). 407 (29.2%) patients were approved for surgery by both electronic screening and anesthesiologist. In 909 (65.2%) cases, the electronic screening system recommended further consultation while the anesthesiologist approved the patient (specificity 30.9% (95%CI 28.4-33.5); poor level of agreement (ĸ = 0.04)). Agreement regarding ASA-PS classification scores was weak (ĸ = 0.48). The majority of patients (78.0%) felt positive about electronic screening replacing the regular preoperative assessment. CONCLUSIONS: Electronic screening can reliably identify patients who can have their first contact with an anesthesiologist on the day of surgery, potentially allowing a major proportion of patients to safely bypass the preoperative clinic.

External Validation of the ACTA-PORT Transfusion Risk Score in Older Cardiac Surgery Patients at Risk of Frailty.

OBJECTIVES: Accurate preoperative transfusion risk stratification may serve to better manage older patients undergoing cardiac surgery. Therefore, the aim of the present study was to externally validate the existing Association of Cardiothoracic Anesthetists perioperative risk of blood transfusion (ACTA-PORT) score in a population ≥70 years of age scheduled for cardiac surgery. Furthermore, the study authors investigated the additional prognostic value of individual frailty variables to this transfusion risk score. DESIGN: A retrospective analysis. SETTING: At a tertiary-care hospital. PARTICIPANTS: Five hundred seven patients aged ≥70 years undergoing elective cardiac surgery from July 2015 to August 2017. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the administration of a perioperative blood transfusion. Frailty domains were assessed in a preanesthesia geriatric assessment, and a priori selection of biomarkers derived from blood was determined. The original ACTA-PORT score resulted in a c-statistic of 0.78 (95% confidence interval 0.74-0.82), with moderate calibration in predicting perioperative allogeneic transfusion in older patients undergoing cardiac surgery. Model updating, using the closed testing procedure, resulted in model revision with a higher discriminatory performance (c-statistic of 0.83, 95% confidence interval 0.79-0.86) and corrected calibration slope. Iron deficiency, impaired nutritional status, and physical impairment were associated with perioperative transfusions. The addition of individual frailty variables to the updated ACTA-PORT model did not result in improved predictive performance. CONCLUSIONS: External validation of the original ACTA-PORT score showed good discrimination and moderate calibration in older patients at risk of frailty undergoing cardiac surgery. Updating the original ACTA-PORT improved the predictive performance. Careful evaluation of additional frailty domains did not add prognostic value to the ACTA-PORT score.

Association of Plasma Fibrinogen and Thromboelastography With Blood Loss in Complex Cardiac Surgery.

Postoperative coagulopathic bleeding is common in cardiac surgery and is associated with increased morbidity and mortality. Ideally, real-time information on in-vivo coagulation should be available. However, up to now it is unclear which perioperative coagulation parameters can be used best to accurately identify patients at increased risk of bleeding. The present study analyzed the associations of perioperative fibrinogen concentrations and whole blood viscoelastic tests with postoperative bleeding in 89 patients undergoing combined cardiac surgery procedures. Postoperative bleeding was recorded until 24 hours after surgery. Regression analyses were performed to establish associations between blood loss and coagulation parameters after cardiopulmonary bypass including a prediction model with known confounding factors for bleeding. Coagulation tests show large changes over the perioperative course with the strongest coagulopathic deviations from baseline after cardiopulmonary bypass. After adjustment for multiple confounders, viscoelastic clot strength instead of fibrinogen concentration showed a similar performance for 24 hour blood loss and a better performance for 6 hour blood loss. This makes intraoperative viscoelastic testing a useful tool to strengthen early clinical decision-making with the potential to reduce perioperative blood transfusions.

Cell salvage in burn excisional surgery.

BACKGROUND: Hemostasis during burn surgery is difficult to achieve, and high blood loss commonly occurs. Bleeding control measures are limited, and many patients require allogeneic blood transfusions. Cell salvage is a well-known method used to reduce transfusions. However, its evidence in burns is limited. Therefore, this study aimed to examine the feasibility of cell salvage during burn surgery. STUDY DESIGN AND METHODS: A prospective, observational study was conducted with 16 patients (20 measurements) scheduled for major burn surgery. Blood was recovered by washing saturated gauze pads with heparinized saline, which was then processed using the Cell Saver. Erythrocyte concentrate quality was analyzed by measuring hemoglobin, hematocrit, potassium, and free hemoglobin concentration. Microbial contamination was assessed based on cultures at every step of the process. Differences in blood samples were tested using the Student's t-test. RESULTS: The red blood cell mass recovered was 29 ± 11% of the mass lost. Patients' preoperative hemoglobin and hematocrit levels were 10.5 ± 1.8 g/dL and 0.33 ± 0.05 L/L, respectively. The erythrocyte concentrate showed hemoglobin and hematocrit levels of 13.2 ± 3.9 g/dL and 0.40 ± 0.11 L/L thus showing a concentration effect. The potassium level was lower in the erythrocyte concentrate (2.5 ± 1.5 vs. 4.1 ± 0.4 mmol/L, p < 0.05). The free hemoglobin level was low (0.16 ± 0.21 µmol/L). All cultures of the erythrocyte concentrate showed bacterial growth compared to 21% of wound cultures. CONCLUSION: Recovering erythrocytes during burn excisional surgery using cell salvage is possible. Despite strict sterile handling, erythrocyte concentrates of all patients showed bacterial contamination. The consequence of this contamination remains unclear and should be investigated in future studies.

Early warning scores in the perioperative period: applications and clinical operating characteristics.

PURPOSE OF REVIEW: Early warnings scores are designed to detect clinical deterioration and promote intervention at the earliest possible moment. Although the ultimate effects on patient outcomes are unclear, early warning scores are now legally mandated in several countries. Here, we review the performance of early warning scores in surgical and perioperative populations. RECENT FINDINGS: Early warning scores can be used to screen for postoperative deterioration and surgical complications. We describe a framework to evaluate the balance between missed events and warning signals that are not followed by an adverse event (nonevents). In large surgical cohort studies, the missed event rates ranged between 19 and 69% and the nonevent rates ranged between 72 and 99% for 'optimal' threshold early warning sores. Recent investigations have shown that there may be a substantial discrepancy between the theoretical benefits shown in validation studies and the practical clinical implementation of early warning scores, which may partly explain the absence of measurable benefit from these systems. SUMMARY: Early warning scores may facilitate protocolized escalation of care for patients at risk of adverse events and can be used in surgical and postoperative patients, but high nonevent rates and practical implementation problems can restrict their usefulness.

Postoperative Airway Obstruction by a Bone Fragment.

Postoperative airway obstructions are potentially life-threatening complications. These obstructions may be classified as functional (sagging tongue, laryngospasm, or bronchospasm), pathoanatomical (airway swelling or hematoma within the airways), or foreign body-related. Various cases of airway obstruction by foreign bodies have previously been reported, for example, by broken teeth or damaged airway instruments. Here we present the exceptional case of a postoperative airway obstruction due to a large fragment of the patient's maxillary bone, left accidentally in situ after transoral surgical tumor resection. Concerning this type of airway obstruction, we discuss possible causes, diagnosis, and treatment options. Although it is an exceptional case after surgery, clinicians should be aware of this potentially life-threatening complication. In summary, this case demonstrates that the differential diagnosis of postoperative airway obstructions should include foreign bodies derived from surgery, including tissue and bone fragments.

The effect of perioperative insulin treatment on cardiodepression in mild adiposity in mice.

BACKGROUND: While most studies focus on cardiovascular morbidity following anesthesia and surgery in excessive obesity, it is unknown whether these intraoperative cardiovascular alterations also occur in milder forms of adiposity without type 2 diabetes and if insulin is a possible treatment to improve intraoperative myocardial performance. In this experimental study we investigated whether mild adiposity without metabolic alterations is already associated with cardiometabolic dysfunction during anesthesia, mechanical ventilation and surgery and whether these myocardial alterations can be neutralized by intraoperative insulin treatment. METHODS: Mice were fed a western (WD) or control diet (CD) for 4 weeks. After metabolic profiling, mice underwent general anesthesia, mechanical ventilation and surgery. Cardiac function was determined with echocardiography and left-ventricular pressure-volume analysis. Myocardial perfusion was determined with contrast-enhanced echocardiography. WD-fed mice were subsequently treated with insulin by hyperinsulinemic euglycemic clamping followed by the same measurements of cardiac function and perfusion. RESULTS: Western-type diet feeding led to a 13 % increase in bodyweight, (p < 0.0001) and increased adipose tissue mass, without metabolic alterations. Despite this mild phenotype, WD-fed mice had decreased systolic and diastolic function (end-systolic elastance was 2.0 ± 0.5 versus 4.1 ± 2.4 mmHg/µL, p = 0.01 and diastolic beta was 0.07 ± 0.03 versus 0.04 ± 0.01 mmHg/µL, p = 0.02) compared to CD-fed mice. Ventriculo-arterial coupling and myocardial perfusion were decreased by 48 % (p = 0.003) and 43 % (p = 0.03) respectively. Insulin treatment in WD-fed mice improved echo-derived systolic function (fractional shortening 42 ± 5 % to 46 ± 3, p = 0.05), likely due to decreased afterload, but there was no effect on load-independent measures of systolic function or myocardial perfusion. However, there was a trend towards improved diastolic function after insulin treatment (43 % improvement, p = 0.05) in WD-fed mice. CONCLUSIONS: Mild adiposity without metabolic alterations already affected cardiac function and perfusion during anesthesia, mechanical ventilation and surgery in mice. Intraoperative insulin may be beneficial to reduce afterload and enhance intraoperative ventricular relaxation, but not to improve ventricular contractility or myocardial perfusion.

Health risk factors in the anesthesia population.

STUDY OBJECTIVE: We investigated the prevalence of lifestyle risk factors in patients admitted to our preoperative assessment outpatient clinic, and compared patient self-reports and anesthetist reports of health risk factors to evaluate the patient self-image of preoperative health status. DESIGN: Cross-sectional survey. SETTING: The study was performed in an academic teaching hospital in Amsterdam, the Netherlands, during 3 consecutive months at the preoperative screening clinic. PATIENTS: A total of 1227 adult patients scheduled for surgery were screened, and 1111 were included (patients being excluded where data were incomplete). INTERVENTIONS AND MEASUREMENTS: Before health risk screening by an anesthetist, patients filled out a lifestyle risk factor questionnaire including overweight, hypertension, diabetes mellitus, smoking, physical activity, and alcohol use. These were compared with risk factors stated in the preoperative assessment report of the anesthetist. MAIN RESULTS: The study population was aged 51 ± 17 years with a body mass index of 25.6 ± 4.7 kg/m(2). The most frequent lifestyle risk factors reported by the anesthetist were overweight and obesity (47.5%), smoking (25.3%), and hypertension (23.7%). The prevalence of no, 1, or 2 lifestyle risk factors in the preoperative assessment outpatient clinic population was, respectively, 30.1%, 35.6%, and 18.5% reported by the anesthetist and 36.4%, 36.7%, and 18.6% reported by the patients. Patients with more lifestyle risk factors were older with a higher body mass index and American Society of Anesthesiologists classification. Differences in reporting of lifestyle risk factors between patients and anesthetist occurred especially with overweight (26.5% vs 47.5%). CONCLUSIONS: The prevalence of lifestyle risk factors in perioperative patients is high, and differences in reporting between patients and anesthetists may suggest that patients are unaware of or ignore their unhealthy state. Further studies are warranted to investigate the association between the lifestyle risk factors and outcome in the anesthesiology setting.

Myocardial Perfusion and Function Are Distinctly Altered by Sevoflurane Anesthesia in Diet-Induced Prediabetic Rats.

Preservation of myocardial perfusion during surgery is particularly important in patients with increased risk for perioperative complications, such as diabetes. Volatile anesthetics, like sevoflurane, have cardiodepressive effects and may aggravate cardiovascular complications. We investigated the effect of sevoflurane on myocardial perfusion and function in prediabetic rats. Rats were fed a western diet (WD; n = 18) or control diet (CD; n = 18) for 8 weeks and underwent (contrast) echocardiography to determine perfusion and function during baseline and sevoflurane exposure. Myocardial perfusion was estimated based on the product of microvascular filling velocity and blood volume. WD-feeding resulted in a prediabetic phenotype characterized by obesity, hyperinsulinemia, hyperlipidemia, glucose intolerance, and hyperglycemia. At baseline, WD-feeding impaired myocardial perfusion and systolic function compared to CD-feeding. Exposure of healthy rats to sevoflurane increased the microvascular filling velocity without altering myocardial perfusion but impaired systolic function. In prediabetic rats, sevoflurane did also not affect myocardial perfusion; however, it further impaired systolic function. Diet-induced prediabetes is associated with impaired myocardial perfusion and function in rats. While sevoflurane further impaired systolic function, it did not affect myocardial perfusion in prediabetic rats. Our findings suggest that sevoflurane anesthesia leads to uncoupling of myocardial perfusion and function, irrespective of the metabolic state.

Predictors of Persistent Neuropathic Pain--A Systematic Review.

BACKGROUND: Characterization of the prognostic variables for persistent neuropathic pain (PNP) remains incomplete despite multiple articles addressing this topic. To provide more insight into the recovery and prognosis of neuropathic pain, high-quality data are required that provide information about the predictors that contribute to the development of PNP. OBJECTIVE: To determine the methodological quality of studies about predictors for PNP and to summarize findings of predictors found in high-quality studies. STUDY DESIGN: A systematic review. SETTING: VU University Medical Center, Amsterdam, The Netherlands. METHODS: Studies were identified by searching the electronic databases PubMed, Embase, and Cochrane Library. Methodological quality of each article was independently assessed by 2 reviewers. RESULTS: Forty-six relevant studies were identified, classified into 4 different neuropathic pain (NP)-syndromes: postherpetic neuralgia (n = 35), radicular pain and sciatica (n = 3), postsurgical pain (n = 6), and other types of NP (n = 2). Seven studies were of high quality. The 3 high-quality studies found for PHN reported male gender, older age, smoking, trauma at the site of lesion, missed antiviral prescriptions, higher acute pain severity, higher rash severity, more neuropathic characteristics, shorter rash duration, and a lower health status as predictors for PNP. For persistence of radicular pain one high-quality study reported negative outcome expectancies, pain-related fear of movement, and passive pain coping as predictors for PNP. Psychological distress, acute pain, breast cancer surgery, higher body mass index, area of secondary hyperalgesia, neuropathic characteristics, hypoesthesia, and hyperesthesia were found to be predictive for postsurgical pain in 3 high-quality studies. LIMITATIONS: Some publications may have been missed during literature search. The low-quality of the studies could be the result of an incomplete description of their methods. CONCLUSIONS: High-quality studies mainly assessed factors related to disease functions and structures. Due to shortcomings in methodological quality and limited areas of predictor selection, there is a need for high-quality studies focusing on predictor measurement, statistical analysis and the use of a standardized set of predictors.

Inhaled carbon monoxide protects time-dependently from loss of hypoxic pulmonary vasoconstriction in endotoxemic mice.

BACKGROUND: Inhaled carbon monoxide (CO) appears to have beneficial effects on endotoxemia-induced impairment of hypoxic pulmonary vasoconstriction (HPV). This study aims to specify correct timing of CO application, it's biochemical mechanisms and effects on inflammatory reactions. METHODS: Mice (C57BL/6; n = 86) received lipopolysaccharide (LPS, 30 mg/kg) intraperitoneally and subsequently breathed 50 ppm CO continuously during defined intervals of 3, 6, 12 or 18 h. Two control groups received saline intraperitoneally and additionally either air or CO, and one control group received LPS but breathed air only. In an isolated lung perfusion model vasoconstrictor response to hypoxia (FiO2 = 0.01) was quantified by measurements of pulmonary artery pressure. Pulmonary capillary pressure was estimated by double occlusion technique. Further, inflammatory plasma cytokines and lung tissue mRNA of nitric-oxide-synthase-2 (NOS-2) and heme oxygenase-1 (HO-1) were measured. RESULTS: HPV was impaired after LPS-challenge (p < 0.01). CO exposure restored HPV-responsiveness if administered continuously for full 18 h, for the first 6 h and if given in the interval between the 3(rd) and 6(th) hour after LPS-challenge (p < 0.05). Preserved HPV was attributable to recovered arterial resistance and associated with significant reduction in NOS-2 mRNA when compared to controls (p < 0.05). We found no effects on inflammatory plasma cytokines. CONCLUSION: Low-dose CO prevented LPS-induced impairment of HPV in a time-dependent manner, associated with a decreased NOS-2 expression.

Perioperative myocardial perfusion: an anesthesiologists' concern?

PURPOSE OF REVIEW: Cardiac complication following noncardiac surgery is the leading cause of death in the perioperative period. Disturbances in myocardial perfusion are at the basis of these complications. The purpose of this review was to summarize the most recent findings on factors affecting myocardial perfusion in the perioperative period and possibilities for monitoring disturbances in myocardial perfusion. RECENT FINDINGS: Clinical studies in cardiovascular healthy patients show mild influences of general anesthetics on myocardial perfusion. No clear benefit could be detected for the use of volatile anesthetics over intravenous anesthetics in patients at risk for disturbances in myocardial perfusion. Etomidate should be used with caution in American Society of Anesthesiologists class 3 and 4 patients. Recent studies focused on effects of decreased perfusion pressure, lowering myocardial oxygen demand and impaired oxygen delivery on myocardial perfusion. Promising results are reported on monitoring perioperative myocardial perfusion using troponin and NT-pro-B-type natriuretic peptides. SUMMARY: General anesthesia only mildly influences myocardial perfusion in cardiovascular healthy patients. Further research is necessary to determine whether this is also the case for cardiovascular-compromised patients. Monitoring troponin levels in the perioperative setting may be useful for predicting cardiovascular events in at-risk patients.

The palliative performance scale applied in high-care residential hospice: a retrospective study.

BACKGROUND: The Palliative Performance Scale (PPS) is a tool that is widely used to predict end of life. In Ontario, Canada, the PPS is used to mark the terminal phase of life and eligibility for terminal care. OBJECTIVE: The aim of this retrospective study was to confirm that a PPS level of 40% can be used as a marker for the terminal phase of life. METHOD: PPS levels from 78 patients were calculated based on the intake reports made at admission to an inpatient hospice. RESULTS: Although 77 patients passed away within a period of 3 months, PPS levels at admission varied from 10% to 70%. Fifty-six percent of all patients had a PPS level of 40% or less. Regarding survival, three significant PPS profiles, consisting of two or more PPS levels could be distinguished.

A favorable course of palliative sedation: searching for indicators using caregivers' perspectives.

OBJECTIVE: Comparing characteristics of a favorable sedation course during palliative sedation to a less favorable course based on the reports Dutch physicians and nurses. RESULTS: Cases identified as having a favorable sedation course less often concerned a male patient (P = .019 nurses' cases), reached the intended sedation depth significantly quicker (P < .05 both nurses and physicians' cases), reached a deeper level of sedation (P = .015 physicians' cases), and had a shorter total duration of sedation compared (P < .001 physicians' cases) to patients with a less favorable sedation course. CONCLUSIONS: A favorable course during palliative sedation seems more probable when health care professionals report on a (relatively) shorter time to reach the required depth of sedation and when a deeper level of sedation can be obtained.

Myocardial blood flow under general anaesthesia with sevoflurane in type 2 diabetic patients: a pilot study.

BACKGROUND: In type 2 diabetic patients, cardiac events in the perioperative period may be associated with diminished myocardial vasomotor function and endothelial dysfunction. The influence of sevoflurane anaesthesia on myocardial endothelial dysfunction in type 2 diabetic mellitus is investigated in this pilot study. METHODS: Six males with type 2 diabetes mellitus and eight healthy controls were included. Using myocardial contrast echocardiography, myocardial blood flow (MBF) was measured at rest, during adenosine-induced hyperaemia (endothelium-independent vasodilation) and after sympathetic stimulation by the cold pressor test (endothelium-dependent vasodilation). Measurements were performed before and after induction of sevoflurane anaesthesia. RESULTS: Sevoflurane anaesthesia decreased resting MBF in diabetics but not in controls (P = 0.03), while baseline MBF did not differ between diabetics and controls. Without anaesthesia, adenosine-induced hyperaemia increased MBF in both groups compared to resting values. Adenosine combined with sevoflurane resulted in a lower hyperaemic MBF in both groups compared to no anaesthesia. Differences in MBF in response to adenosine before and after sevoflurane administration were larger in diabetic patients, however not statistically significant in this pilot group (P = 0.08). Myocardial blood flow parameters after the cold pressor test were not different between groups. CONCLUSION: These pilot data in type 2 diabetic patients show that sevoflurane anaesthesia decreases resting myocardial blood flow compared to healthy controls. Further, we observed a trend towards a lower endothelium-independent vasodilation capacity in diabetic patients under sevoflurane anaesthesia. Endothelium-dependent vasodilation was not affected by sevoflurane in diabetic patients. These data provide preliminary insight into myocardial responses in type 2 diabetic patients under general anaesthesia. TRIAL REGISTRATION: http://www.clinicialtrials.gov, NCT00866801.

Ten-year patterns in blood product utilization during cardiothoracic surgery with cardiopulmonary bypass in a tertiary hospital.

BACKGROUND: This retrospective analysis describes blood conservation strategies and overall consumption of red blood cells (RBCs), fresh-frozen plasma (FFP), and platelet (PLT) concentrates during nonaortic cardiac surgery with cardiopulmonary bypass (CPB) in a tertiary hospital over a 10-year period. STUDY DESIGN AND METHODS: Study variables of 6026 patients that underwent cardiac surgery between 2002 and 2011 were incorporated in the database and included hemoglobin (Hb), lowest temperature, CPB duration, 24-hour blood loss, fluid balance, and overall transfusion requirements. RESULTS: Between 2002 and 2011, the lowest intraoperative Hb levels and temperature increased from 8.5 ± 1.2 to 10.4 ± 1.4 g/dL and from 32 ± 2 to 34 ± 1°C, respectively. In addition to the steep decrease in the postoperative fluid balance over time, a reduction in 24-hour blood loss from 815 ± 588 mL (2002) to 590 ± 438 mL (2011) was observed. These changes were paralleled by a 28% reduction in overall RBC transfusion from 1443 units in 2002 to 1038 in 2011. While RBC transfusion decreased over time, there was no significant change in the use of FFP or PLT concentrate transfusion. The probability to receive RBC transfusion increased after cessation of aprotinin, but reduced after routine cell salvage in all operations. CONCLUSION: This institutional report shows a large reduction in blood loss and transfusion requirements in cardiac surgery over a 10-year period. This reduction is most probably attributed to structural cell salvage, reduced intraoperative fluid volumes, and the increase in the lowest intraoperative body temperature.

Inverse intubation in entrapped trauma casualties: a simulator based, randomised cross-over comparison of direct, indirect and video laryngoscopy.

BACKGROUND: Airway management in entrapped casualties with restricted access to the head is challenging. If tracheal intubation is required and conventional laryngoscopy is not possible, intubation must be attempted in a face-to-face approach. Traditionally, this is performed with a standard laryngoscope held in the right hand with the blade facing upward. Recently, alternative methods have been developed to facilitate difficult intubations, and we hypothesised that such techniques are also useful for face-to-face intubations. METHODS: 24 (trainee) anaesthesiologists attempted tracheal intubation in a patient simulator (SimMan, Laerdal, Norway) using three techniques in random order: (1) direct laryngoscopy (Macintosh blade #3), (2) indirect optical laryngoscopy (Airtraq, Prodol, Spain) and (3) video laryngoscopy (McGrath, Aircraft Medical, UK). The manikin was sitting with the neck immobilised and only accessible from the left anterolateral side. Success rate (percentage (95% CI)) and tube insertion time (median (IQR)) were recorded. RESULTS: Success rate did not differ significantly (Airtraq and McGrath 100% (84% to 100%), direct laryngoscopy 88% (68% to 96%)). Intubation was faster with Airtraq (25 s (22-34), p<0.001) and direct laryngoscopy (34 s (22-48), p<0.05) compared with the McGrath technique (55 s (37-96)). CONCLUSIONS: All three techniques have a high success rate, but the usefulness of the video laryngoscope is limited due to longer intubation duration. Inverse direct laryngoscopy showed reasonable intubation times and, given the widespread availability of Macintosh laryngoscopes, seems a useful technique. Intubation was always successful and tended to be fastest with the Airtraq device, suggesting that this technique may be a promising alternative.

General anesthesia with sevoflurane decreases myocardial blood volume and hyperemic blood flow in healthy humans.

BACKGROUND: Preservation of myocardial perfusion during general anesthesia is likely important in patients at risk for perioperative cardiac complications. Data related to the influence of general anesthesia on the normal myocardial circulation are limited. In this study, we investigated myocardial microcirculatory responses to pharmacological vasodilation and sympathetic stimulation during general anesthesia with sevoflurane in healthy humans immediately before surgical stimulation. METHODS: Six female and 7 male subjects (mean age 43 years, range 28-61) were studied at baseline while awake and during the administration of 1 minimum alveolar concentration sevoflurane. Using myocardial contrast echocardiography, myocardial blood flow (MBF) and microcirculatory variables were assessed at rest, during adenosine-induced hyperemia, and after cold pressor test-induced sympathetic stimulation. MBF was calculated from the relative myocardial blood volume multiplied by its exchange frequency (ß) divided by myocardial tissue density (ρT), which was set at 1.05 g·mL(-1). RESULTS: During sevoflurane anesthesia, MBF at rest was similar to baseline values (1.05 ± 0.28 vs 1.05 ± 0.32 mL·min(-1)·g(-1); P = 0.98; 95% confidence interval [CI], -0.18 to 0.18). Myocardial blood volume decreased (P = 0.0044; 95% CI, 0.01-0.04) while its exchange frequency (ß) increased under sevoflurane anesthesia when compared with baseline. In contrast, hyperemic MBF was reduced during anesthesia compared with baseline (2.25 ± 0.5 vs 3.53 ± 0.7 mL·min(-1)·g(-1); P = 0.0003; 95% CI, 0.72-1.84). Sympathetic stimulation during sevoflurane anesthesia resulted in a similar MBF compared to baseline (1.53 ± 0.53 and 1.55 ± 0.49 mL·min(-1)·g(-1); P = 0.74; 95% CI, -0.47 to 0.35). CONCLUSIONS: In otherwise healthy subjects who are not subjected to surgical stimulation, MBF at rest and after sympathetic stimulation is preserved during sevoflurane anesthesia despite a decrease in myocardial blood volume. However, sevoflurane anesthesia reduces hyperemic MBF, and thus MBF reserve, in these subjects.