Comparison of cerebral oxygen desaturation events between children under general anesthesia and chloral hydrate sedation - a randomized controlled trial.

BACKGROUND: During pediatric general anesthesia (GA) and sedation, clinicians aim to maintain physiological parameters within normal ranges. Accordingly, regional cerebral oxygen saturation (rScO2) should not drop below preintervention baselines. Our study compared rScO2 desaturation events in children undergoing GA or chloral hydrate sedation (CHS). METHODS: Ninety-two children undergoing long auditory assessments were randomly assigned to two study arms: CHS (n = 40) and GA (n = 52). Data of 81 children (mean age 13.8 months, range 1-36 months) were analyzed. In the GA group, we followed a predefined 10 N concept (no fear, no pain, normovolemia, normotension, normocardia, normoxemia, normocapnia, normonatremia, normoglycemia, and normothermia). In this group, ENT surgeons performed minor interventions in 29 patients based on intraprocedural microscopic ear examinations. In the CHS group, recommendations for monitoring and treatment of children undergoing moderate sedation were met. Furthermore, children received a double-barreled nasal oxygen cannula to measure end-tidal carbon dioxide (etCO2) and allow oxygen administration. Chloral hydrate was administered in the parent's presence. Children had no intravenous access which is an advantage of sedation techniques. In both groups, recommendations for fasting were followed and an experienced anesthesiologist was present during the entire procedure. Adverse event (AE) was a decline in cerebral oxygenation to below 50% or below 20% from the baseline for ≥1 min. The primary endpoint was the number of children with AE across the study arms. Secondary variables were: fraction of inspired oxygen (FIO2), oxygen saturation (SpO2), etCO2, systolic and mean blood pressure (BP), and heart rate (HR); these variables were analyzed for their association with drop in rScO2 to below baseline (%drop_rScO2). RESULTS: The incidence of AE across groups was not different. The analysis of secondary endpoints showed evidence that %drop_rScO2 is more dependent on HR and FIO2 than on BP and etCO2. CONCLUSIONS: This study highlights the strong association between HR and rScO2 in children aged < 3 years, whereas previous studies had primarily discussed the role of BP and etCO2. Prompt HR correction may result in shorter periods of cerebral desaturation. TRIAL REGISTRATION: The study was retrospectively registered with the German Clinical Trials Registry (DRKS00024362, 04/02/2021).

In vitro performance evaluation of AnaConDaTM-100 and AnaConDaTM-50 compared to a circle breathing system for control and consumption of volatile anaesthetics.

To identify the better volatile anaesthetic delivery system in an intensive care setting, we compared the circle breathing system and two models of reflection systems (AnaConDa™ with a dead space of 100 ml (ACD-100) or 50 ml (ACD-50)). These systems were analysed for the parameters like wash-in, consumption, and wash-out of isoflurane and sevoflurane utilising a test lung model. The test lung was connected to a respirator (circle breathing system: Aisys CS™; ACD-100/50: Puriton Bennett 840). Set parameters were volume-controlled mode, tidal volume-500 ml, respiratory rate-10/min, inspiration time-2 sec, PEEP-5 mbar, and oxygen-21%. Wash-in, consumption, and wash-out were investigated at fresh gas flows of 0.5, 1.0, 2.5, and 5.0 l/min. Anaesthetic target concentrations were 0.5, 1.0, 1.5, 2.0, and 2.5%.  Wash-in was slower in ACD-100/-50 compared to the circle breathing system, except for fresh gas flows of 0.5 and 1.0 l/min. The consumption of isoflurane and sevoflurane in ACD-100 and ACD-50 corresponded to the fresh gas flow of 0.5-1.0 l/min in the circle breathing system. Consumption with ACD-50 was higher in comparison to ACD-100, especially at gas concentrations > 1.5%. Wash-out was quicker in ACD-100/-50 than in the circle breathing system at a fresh gas flow of 0.5 l/min, however, it was longer at all the other flow rates. Wash-out was comparable in ACD-100 and ACD-50. Wash-in and wash-out were generally quicker with the circle breathing system than in ACD-100/-50. However, consumption at 0.5 minimum alveolar concentration was comparable at flows of 0.5 and 1.0 l/min.

Comparison of 3 Methods to Assess Occupational Sevoflurane Exposure in Abdominal Surgeons: A Single-Center Observational Pilot Study.

BACKGROUND: Studies demonstrated that operating room personnel are exposed to anesthetic gases such as sevoflurane (SEVO). Measuring the gas burden is essential to assess the exposure objectively. Air pollution measurements and the biological monitoring of urinary SEVO and its metabolite hexafluoroisopropanol (HFIP) are possible approaches. Calculating the mass of inhaled SEVO is an alternative, but its predictive power has not been evaluated. We investigated the SEVO burdens of abdominal surgeons and hypothesized that inhaled mass calculations would be better suited than pollution measurements in their breathing zones (25 cm around nose and mouth) to estimate urinary SEVO and HFIP concentrations. The effects of potentially influencing factors were considered. METHODS: SEVO pollution was continuously measured by photoacoustic gas monitoring. Urinary SEVO and HFIP samples, which were collected before and after surgery, were analyzed by a blinded environmental toxicologist using the headspace gas chromatography-mass spectrometry method. The mass of inhaled SEVO was calculated according to the formula mVA = cVA·(Equation is included in full-text article.)·t·ρ VA aer. (mVA: inhaled mass; cVA: volume concentration; (Equation is included in full-text article.): respiratory minute volume; t: exposure time; and ρ VA aer.: gaseous density of SEVO). A linear multilevel mixed model was used for data analysis and comparisons of the different approaches. RESULTS: Eight surgeons performed 22 pancreatic resections. Mean (standard deviation [SD]) SEVO pollution was 0.32 ppm (0.09 ppm). Urinary SEVO concentrations were below the detection limit in all samples, whereas HFIP was detectable in 82% of the preoperative samples in a mean (SD) concentration of 8.53 µg·L (15.53 µg·L; median: 2.11 µg·L, interquartile range [IQR]: 4.58 µg·L) and in all postoperative samples (25.42 µg·L [21.39 µg·L]). The mean (SD) inhaled SEVO mass was 5.67 mg (2.55 mg). The postoperative HFIP concentrations correlated linearly to the SEVO concentrations in the surgeons' breathing zones (ß = 216.89; P < .001) and to the calculated masses of inhaled SEVO (ß = 4.17; P = .018). The surgeon's body mass index (BMI), age, and the frequency of surgeries within the last 24 hours before study entry did not influence the relation between HFIP concentration and air pollution or inhaled mass, respectively. CONCLUSIONS: The biological SEVO burden, expressed as urinary HFIP concentration, can be estimated by monitoring SEVO pollution in the personnel's individual breathing zone. Urinary SEVO was not an appropriate biomarker in this setting.

Incidence of infection in non-tunnelled thoracic epidural catheters after major abdominal surgery.

BACKGROUND: Thoracic epidural analgesia is beneficial after major abdominal surgery, though side-effects and complications are rare but potentially devastating. The incidence of catheter-related infection is approximately 5.5%. Several guidelines have been recommended to prevent complications during thoracic epidural catheterization. Tunnelling is often recommended to reduce the incidence of infections and dislocations. METHODS: A retrospective, single-centre analysis of our acute pain service database was performed between 2010 and 2018. The hygiene measures of the German Society of Anaesthesiology have been incorporated in our standard operating protocol since 2009. The procedure remained constant, but the skin disinfectant was changed from propan-2-ol to propan-2-ol with octenidine in 2014. Tunnelling of catheters was not performed. We analysed the incidence of catheter-related infections (primary endpoint) and effect of the used disinfectant (secondary endpoint). RESULTS: A total of 2755 patients underwent elective major abdominal surgery with thoracic epidural catheterization. Sixteen patients (0.6%) showed symptoms of mild catheter-related infection. Moderate or severe infections were not observed in any patient. The type of disinfectant did not show any significant effect on the incidence of infection. CONCLUSION: The incidence of catheter-related infections was low, and only mild signs of infection were observed. Non-tunnelling could be an alternative to tunnelling, especially if hygiene protocols are followed, and the duration of catheter use is short. A comprehensive database and regular examinations by trained staff are essential for early detection of abnormalities and immediate removal of the catheter, if required.

Improvement in pre-operative risk assessment in adults undergoing noncardiac surgery by a process-oriented score: A prospective single-centre study.

BACKGROUND: Pre-operative risk assessment is important to quantify the patient's risks of morbidity and mortality, but its quality differs. We created a process-oriented score (PRO-score) for risk evaluation of adults as a three-stage warning score checklist with concrete guidance. It contains the contents of current guidelines and the assessment of vital signs. OBJECTIVES: We investigated whether the PRO-score is suitable to detect 'red flag' warning signs not only in American Society of Anesthesiologists (ASA) physical status (PS) 3 or 4 patients but also in ASA-PS 1 or 2 patients. Resulting medical, therapeutic or structural consequences were recorded. DESIGN: Prospective single-centre study. SETTING: The study was performed in a German university hospital between November 2015 and December 2018. PATIENTS: We included 54 455 adult patients undergoing a pre-operative risk assessment for general or regional anaesthesia and elective noncardiac surgery. RESULTS: In all, 388 patients presented 'red flag' warning signs in the PRO-score during risk assessment; 85 (21.9%) were labelled ASA-PS 1 or 2, 244 (62.9%) ASA-PS 3 and 59 (15.2%) ASA-PS 4. Additional examinations were performed in 179 patients and technical tests in 175 patients (ASA-PS 1 or 2: 53 and 63 patients, respectively). After re-evaluation of the peri-operative risk in an interdisciplinary conference, surgery was cancelled in 44 patients (ASA-PS 1 and 2, 17 patients) or performed under local anaesthesia in 15 patients (ASA-PS 1 and 2, 2 patients). A downgrading to PRO-score 2 was reached in 168 patients after therapeutic interventions (ASA-PS 1 and 2, 54 patients). Undergoing surgery despite 'red flag' events resulted in major complications in 34 patients, and 16 patients died (ASA-PS 1 or 2: 7 and 3 patients, respectively). CONCLUSION: The PRO-score detected warning signs in 'healthy' ASA-PS 1 or 2 and in ASA-PS 3 or 4 patients. Furthermore, it influenced the management of these patients, and thus improved the process quality of risk assessment. The physical examination should include the assessment of vital signs.

Environmental safety: Air pollution while using MIRUS™ for short-term sedation in the ICU.

BACKGROUND: MIRUS™ is a device for target-controlled inhalational sedation in the ICU in combination with use of isoflurane, or sevoflurane, or desflurane. The feasibility of this device has recently been proven; however, ICU staff exposure may restrict its application. We investigated ICU ambient room pollution during daily work to estimate ICU personnel exposure while using MIRUS™. METHODS: This observational study assessed pollution levels around 15 adult surgical patients who received volatile anaesthetics-based sedation for a median of 11 hours. Measurements were performed by photoacoustic gas monitoring in real-time at different positions near the patient and in the personnel's breathing zone. Additionally, the impact of the Clean Air™ open reservoir scavenging system on volatile agent pollution was evaluated. RESULTS: Baseline concentrations [ppm] during intervention and rest periods were isoflurane c¯mean = 0.58 ± 0.49, c¯max = 5.72; sevoflurane c¯mean = 0.22 ± 0.20, c¯max = 7.93; and desflurane c¯mean = 0.65 ± 0.57, c¯max = 6.65. Refilling MIRUS™ with liquid anaesthetic yielded gas concentrations of c¯mean = 2.18 ± 1.48 ppm and c¯max = 13.03 ± 9.37 ppm in the personnel's breathing zone. Air pollution in the patient's room was approximately five times higher without a scavenging system. CONCLUSION: Ambient room pollution was minimal in most cases, and the measured values were within or below the recommended exposure limits. Caution should be taken during refilling of the MIRUS™ system, as this was accompanied by higher pollution levels. The combined use of air-conditioning and gas scavenging systems is strongly recommended.

Kinetics of isoflurane and sevoflurane in a unidirectional displacement flow and the relevance to anesthetic gas exposure by operating room personnel.

International guidelines recommend the use of ventilation systems in operating rooms to reduce the concentration of potentially hazardous substances such as anesthetic gases. The exhaust air grilles of these systems are typically located in the lower corners of the operating room and pick up two-thirds of the air volume, whereas the final third is taken from near the ceiling, which guarantees an optimal perfusion of the operating room with a sterile filtered air supply. However, this setup is also employed because anesthetic gases have a higher molecular weight than the components of air and should pool on the floor if movement is kept to a minimum and if a ventilation system with a unidirectional displacement flow is employed. However, this anticipated pooling of volatile anesthetics at the floor level has never been proven. Thus, we herein investigated the flow behaviors of isoflurane, sevoflurane, and carbon dioxide (for comparison) in a measuring chamber sized 2.46 × 1.85 × 5.40 m with a velocity of 0.3 m/sec and a degree of turbulence <20%. Gas concentrations were measured at 1,728 measuring positions throughout the measuring chamber, and the flow behaviors of isoflurane and sevoflurane were found to be similar, with an overlap of 90%. The largest spread of both gases was 55 cm at 5.4 m from the emission source. Interestingly, neither isoflurane nor sevoflurane was detected at floor level, but a continuous cone-like spreading was observed due to gravity. In contrast, carbon dioxide accumulated at floor level in the form of a gas cloud. Thus, floor level exhaust ventilation systems are likely unsuitable for the collection and removal of anesthetic gases from operating rooms.

The Personnel's Sevoflurane Exposure in the Postanesthesia Care Unit Measured by Photoacoustic Gas Monitoring and Hexafluoroisopropanol Biomonitoring.

PURPOSE: Room ventilation in the postanesthesia care unit (PACU) is often poor, although patients exhale anesthetic gases. We investigated the PACU personnel's environmental and biological sevoflurane (SEVO) burden during patient care. DESIGN: Prospective, observational study. METHODS: Air pollution was measured by photoacoustic gas monitoring in the middle of the PACU, above the patient's face, and on the PACU corridor. Urinary SEVO and hexafluoroisopropanol concentrations were determined. FINDINGS: Mean air pollution was 0.34 ± 0.07 ppm in the middle of the PACU, 0.56 ± 0.17 ppm above the patient's face, and 0.47 ± 0.06 ppm on the corridor. Biological preshift exposure levels were 0.13 ± 0.03 mcg/L (SEVO) and 4.72 ± 5.41 mcg/L (hexafluoroisopropanol). Postshift concentrations increased significantly to 0.20 ± 0.06 mcg/L (P = .004) and 42.18 ± 27.82 mcg/L (P < .001). CONCLUSIONS: PACU personnel were environmentally and biologically exposed to SEVO, but exposure levels were minimal according to current recommendations.

Survival after long-term isoflurane sedation as opposed to intravenous sedation in critically ill surgical patients: Retrospective analysis.

BACKGROUND: Isoflurane has shown better control of intensive care sedation than propofol or midazolam and seems to be a useful alternative. However, its effect on survival remains unclear. OBJECTIVE: The objective of this study is to compare mortality after sedation with either isoflurane or propofol/midazolam. DESIGN: A retrospective analysis of data in a hospital database for a cohort of consecutive patients. SETTING: Sixteen-bed interdisciplinary surgical ICU of a German university hospital. PATIENTS: Consecutive cohort of 369 critically ill surgical patients defined within the database of the hospital information system. All patients were continuously ventilated and sedated for more than 96 h between 1 January 2005 and 31 December 2010. After excluding 169 patients (93 >79 years old, 10 <40 years old, 46 mixed sedation, 20 lost to follow-up), 200 patients were studied, 72 after isoflurane and 128 after propofol/midazolam. INTERVENTIONS: Sedation with isoflurane using the AnaConDa system compared with intravenous sedation with propofol or midazolam. MAIN OUTCOME MEASURES: Hospital mortality (primary) and 365-day mortality (secondary) were compared with the Kaplan-Meier analysis and a log-rank test. Adjusted odds ratios (ORs) [with 95% confidence interval (95% CI)] were calculated by logistic regression analyses to determine the risk of death after isoflurane sedation. RESULTS: After sedation with isoflurane, the in-hospital mortality and 365-day mortality were significantly lower than after propofol/midazolam sedation: 40 versus 63% (P = 0.005) and 50 versus 70% (P = 0.013), respectively. After adjustment for potential confounders (coronary heart disease, chronic obstructive pulmonary disease, acute renal failure, creatinine, age and Simplified Acute Physiology Score II), patients after isoflurane were at a lower risk of death during their hospital stay (OR 0.35; 95% CI 0.18 to 0.68, P = 0.002) and within the first 365 days (OR 0.41; 95% CI 0.21 to 0.81, P = 0.010). CONCLUSION: Compared with propofol/midazolam sedation, long-term sedation with isoflurane seems to be well tolerated in this group of critically ill patients after surgery.

Application of the modular approach to an in-house validation study of real-time PCR methods for the detection and serogroup determination of verocytotoxigenic Escherichia coli.

European Commission regulation 2073/2005 on the microbiological criteria for food requires that Escherichia coli is monitored as an indicator of hygienic conditions. Since verocytotoxigenic E. coli (VTEC) strains often cause food-borne infections by the consumption of raw food, the Biological Hazards (BIOHAZ) panel of the European Food Safety Authority (EFSA) recommended their monitoring in food as well. In particular, VTEC strains belonging to serogroups such as O26, O103, O111, O145, and O157 are known causative agents of several human outbreaks. Eight real-time PCR methods for the detection of E. coli toxin genes and their variants (stx(1), stx(2)), the intimin gene (eae), and five serogroup-specific genes have been proposed by the European Reference Laboratory for VTEC (EURL-VTEC) as a technical specification to the European Normalization Committee (CEN TC275/WG6). Here we applied a "modular approach" to the in-house validation of these PCR methods. The modular approach subdivides an analytical process into separate parts called "modules," which are independently validated based on method performance criteria for a limited set of critical parameters. For the VTEC real-time PCR module, the following parameters are being assessed: specificity, dynamic range, PCR efficiency, and limit of detection (LOD). This study describes the modular approach for the validation of PCR methods to be used in food microbiology, using single-target plasmids as positive controls and showing their applicability with food matrices.

Droplets and aerosols: An artificial dichotomy in respiratory virus transmission.

In the medical literature, three mutually non-exclusive modes of pathogen transmission associated with respiratory droplets are usually identified: contact, droplet, and airborne (or aerosol) transmission. The demarcation between droplet and airborne transmission is often based on a cut-off droplet diameter, most commonly 5 µm. We argue here that the infectivity of a droplet, and consequently the transmissivity of the virus, as a function of droplet size is a continuum, depending on numerous factors (gravitational settling rate, transport, and dispersion in a turbulent air jet, viral load and viral shedding, virus inactivation) that cannot be adequately characterized by a single droplet diameter. We propose instead that droplet and aerosol transmission should be replaced by a unique airborne transmission mode, to be distinguished from contact transmission.

Alfred Russel Wallace and the antivaccination movement in Victorian England.

Alfred Russel Wallace, eminent naturalist and codiscoverer of the principle of natural selection, was a major participant in the antivaccination campaigns in late 19th-century England. Wallace combined social reformism and quantitative arguments to undermine the claims of provaccinationists and had a major impact on the debate. A brief account of Wallace's background, his role in the campaign, and a summary of his quantitative arguments leads to the conclusion that it is unwarranted to portray Victorian antivaccination campaigners in general as irrational and antiscience. Public health policy can benefit from history, but the proper context of the evidence used should always be kept in mind.

Feasibility and efficacy of preoperative epidural catheter placement for anterior scoliosis surgery.

BACKGROUND: Postoperative pain control via thoracic epidural catheters (TECs) is an important aspect of postoperative care, and ample evidence highlights its positive physiologic effects and superiority to intravenous analgesia. If epidural catheters for postoperative pain relief are used in scoliosis surgery, current practice is the intraoperative placement of the TEC by the surgeon because preoperative placement is considered challenging and dangerous. On the basis of magnetic resonance imaging of scoliotic spines, the authors developed a technique for preoperative placement of TEC and investigated its safety and feasibility. METHODS: Patients undergoing anterior scoliosis surgery were included, who received preoperative placement of TEC. Postoperative pain, problems associated with the TEC placement, possible side effects, radiographic data, and insertion levels of the TEC were noted. RESULTS: The apex vertebra was identified as a possible site for TEC placement due to dural sac shift leaving a wider epidural space on the convex side. Scoliosis-induced rotation of the vertebrae required realignment of the needle toward the convex side. Sixty patients were included. The success rate for TEC placement was 96.6%: one failed attempt, one catheter placed intrapleurally, and one patient with Horner syndrome. Seven percent of patients required additional rescue analgesia. All other patients had pain scores within acceptable limits (Visual Analogue Scale <5). CONCLUSIONS: The authors have demonstrated that it is possible to insert a TEC in patients with scoliotic spines with a high degree of success using a redesigned approach and thus provide adequate postoperative analgesia with a single epidural catheter. However, precautions have to be taken.

Migratory birds, the H5N1 influenza virus and the scientific method.

BACKGROUND: The role of migratory birds and of poultry trade in the dispersal of highly pathogenic H5N1 is still the topic of intense and controversial debate. In a recent contribution to this journal, Flint argues that the strict application of the scientific method can help to resolve this issue. DISCUSSION: We argue that Flint's identification of the scientific method with null hypothesis testing is misleading and counterproductive. There is far more to science than the testing of hypotheses; not only the justification, bur also the discovery of hypotheses belong to science. We also show why null hypothesis testing is weak and that Bayesian methods are a preferable approach to statistical inference. Furthermore, we criticize the analogy put forward by Flint between involuntary transport of poultry and long-distance migration. SUMMARY: To expect ultimate answers and unequivocal policy guidance from null hypothesis testing puts unrealistic expectations on a flawed approach to statistical inference and on science in general.

Sleep disturbances after posterior scoliosis surgery with an intraoperative wake-up test using remifentanil.

BACKGROUND: The intraoperative wake-up test is a standard procedure for early recognition of neurologic complications after posterior correction of idiopathic scoliosis. In this prospective, single-blinded cohort study, the impact of the wake-up test and the opioid used for anesthesia on the quality of the patients' sleep after scoliosis surgery was investigated up to 12 months postoperatively. METHODS: Patients were classified into three groups: posterior instrumentation with wake-up test using remifentanil, anterior instrumentation without wake-up test using sufentanil, and posterior instrumentation with wake-up test using sufentanil. The quality of sleep was assessed using the Pittsburgh Sleep Quality Index questionnaire preoperatively as well as 3, 6, and 12 months postoperatively. In addition, data were collected on patients' age, weight, and sex, as well as the duration of the operation and anesthesia, amount of blood loss, specific opioid dosages, and wake-up test times. Statistical analysis was conducted using the Mann-Whitney, Kruskal-Wallis, and Wilcoxon tests. RESULTS: There were no differences between groups with regard to baseline characteristics. No explicit recall was assessed through all groups. At 3 and 6 months postoperatively, the sleep quality in the posterior-remifentanil group was significantly poorer than preoperatively and compared with the anterior- and posterior-sufentanil groups. No significant differences in wake-up test times between groups undergoing posterior instrumentation occurred. CONCLUSIONS: This study suggests that patients undergoing scoliosis surgery with an intraoperative wake-up test using remifentanil had impaired sleep quality that lasted up to 6 months postoperatively. No deterioration in sleep quality was observed with sufentanil. Large randomized trials are now needed to confirm these preliminary results.

A note on the inactivation of influenza A viruses by solar radiation, relative humidity and temperature.

We critically investigate the claim put forward by Sagripanti and Lytle ([2007] Photochem. Photobiol. 83, 1278-1282) that inactivation of influenza A virus by solar radiation can explain the seasonality of influenza epidemics. We correct an error in the Sagripanti and Lytle paper and show that changes in relative humidity and temperature affect influenza virus inactivation as strongly as variation in solar radiation. Furthermore, it appears unlikely that transmission in outdoor settings plays an important role during influenza outbreaks, because influenza A virus is sensitive to a wide range of environmental factors.

The impact of the anesthetic conserving device on occupational exposure to isoflurane among intensive care healthcare professionals.

BACKGROUND: Use of anesthetic conserving devices (ACD) for inhalational isoflurane sedation in Intensive Care Units (ICU) has grown in recent years, and healthcare professionals are concerned about isoflurane pollution and exposure-related health risks. Real-time measurements to determine isoflurane exposure in ICU personnel during short-term patient care procedures and ACD handling have not yet been performed. METHODS: Isoflurane concentrations in the breathing zones of ICU staff (25 cm around the nose and mouth) were measured, by photoacoustic gas monitoring, during daily practice including tracheal suctioning, oral hygiene, body care, and patient positioning. Isoflurane pollution was further determined during ACD replacement, syringe filling, and after isoflurane spillages. RESULTS: The average mean isoflurane concentration 25 cm above patients' tracheostoma was 0.3 ppm. Mean (cmean) and maximum (cmax) isoflurane exposure in personnel's breathing zones during patient care ranged from 0.4 to 1.9 ppm and 0.7 to 6.6 ppm, respectively. Isoflurane exposure during ACD replacement was cmean 0.5 to 17.4 ppm and cmax 0.8 to 114.3 ppm. Isoflurane concentrations during ACD syringe filling ranged from 2.4 to 9.1 ppm. The maximum isoflurane concentrations after spillage were dose-dependent. CONCLUSIONS: Use of ACDs and patient physical manipulation are accompanied by isoflurane pollution. Baseline concentrations did not exceed long-term exposure limits, but short-term limits were occasionally exceeded during patient care procedures and ACD handling. Spillages should be avoided, especially when air-conditioning and scavenging systems are unavailable.

Kappa-opioid receptor antagonism improves recovery from myocardial stunning in chronically instrumented dogs.

We tested the hypothesis that the selective kappa-opioid receptor antagonist nor-binaltorphimine (nor-BNI) improves recovery from myocardial stunning. Ten dogs were chronically instrumented for measurement of heart rate, left atrial, aortic and left ventricular pressure (LVP), and the maximum rate of LVP increase (LV dP/dt(max)) and decrease (LV dP/dt(max)), coronary blood flow velocity and myocardial wall-thickening fraction. Regional myocardial blood flow was determined with fluorescent microspheres. Catecholamine plasma levels were measured by high-performance liquid chromatography, and beta-endorphin and dynorphin plasma levels by radioimmunoassay. An occluder around the left anterior descending artery (LAD) allowed induction of a reversible LAD-ischemia. Animals underwent two experiments in a randomized crossover fashion on separate days: (a) 10 min LAD-occlusion (control experiment), (b) second ischemic episode 24 h after nor-BNI (2.5 mg/kg IV) (intervention). Dogs receiving nor-BNI showed an increase in wall-thickening fraction, LV dP/dt(max) and LV dP/dt(min) before ischemia and during the whole reperfusion (P < 0.05 versus control experiment). After nor-BNI pretreatment, dynorphin levels increased after induction of ischemia to a peak level of 15.1 +/- 3.6 pg/mL (P < 0.05 versus control experiment). The increase in plasma beta-endorphin during ischemia and early reperfusion was attenuated after nor-BNI. Compared with the control experiment, nor-BNI left global hemodynamics, regional myocardial blood flow, and catecholamine levels unchanged. In conclusion, nor-BNI improves recovery from myocardial stunning after regional myocardial ischemia in chronically instrumented dogs.