Abstract: Expired gas analysis has been largely relegated to the measurement of VO2 and VCO2 by a variety of methods. We designed and built a new flexible automated expired gas analysis instrument, the Volume Accumulating Metabolic Monitor (VAMM), capable of simultaneous and continuous quantitative expired gas analysis for a multiplicity of gas species. All expired gas is collected into one of two twin reservoirs. This approach allows analysis of one reservoir while collection occurs into the other. The instrument mixes the expired gas and determines the volume of the desired gas species using a combination of indicator gas dilution and mass spectrometry. We tested the VAMM's ability to measure the 13CO2 2-hr collection after intravenous 13C-aminopyrine. Aminopyrine is metabolized to CO2. Ten healthy volunteers underwent expired gas collection and analysis for 140 min. All studies were performed in the recumbent posture after an 8 hr fast. The initial 20 min were used to establish a baseline 13CO2 production. Following the injection of 2 mg/kg 13C-aminopyrine, expired gas was collected for an additional 120 min. The mean 2-hr 13CO2 enrichment was 7.1 ?2.9 ml (range 3.5 ml to 13.2 ml). This represented a percent collection of 26.8 ?9.1 (range 16.5 to 48.6). Peak excretion occurred at 84.9 ?17.5 min (range 50 min to 108 min). The VAMM provided significantly better 13CO2 excretion profiles than previously described. This technology can easily be customized to study not only other similar metabolic processes but also other gas excretions.
Abstract: Extended hepatic resection (more than four liver segments) is a major operative procedure that is associated with significant risk. The purpose of this study was to assess the impact of perioperative variables on in-hospital mortality after extended hepatectomy.
Abstract: Metabolic monitoring devices used in the critical care setting are subject to a range of conditions that may compromise their accuracy. We sought to investigate the error and precision of the Deltatrac metabolic monitor under these conditions.
Abstract: Conventional gas-exchange instruments are confined to the measurement of O(2) consumption (VO(2)) and CO(2) production (VCO(2)) and are subject to a variety of errors. This handicaps the performance of these devices at inspired O(2) fraction (FI(O(2))) > 0.40 and limits their applicability to indirect calorimetry only. We describe a device based on the automation of the Douglas bag technique that is capable of making continuous gas-exchange measurements of multiple species over a broad range of experimental conditions. This system is validated by using a quantitative methanol-burning lung model modified to provide reproducible (13)CO(2) production. The average error for VO(2) and VCO(2) over the FI(O(2)) range of 0.21-0.8. is 2.4 and 0.8%, respectively. The instrument is capable of determining the differential atom% volume of known references of (13)CO(2) to within 3.4%. This device reduces the sources of error that thwart other instruments at FI(O(2)) > 0. 40 and demonstrates the capacity to explore other expressions of metabolic activity in exhaled gases related to the excretion of (13)CO(2).
Abstract: We compared the efficacy of the combination of enalaprilat/labetalol with that of enalaprilat/nicardipine to prevent emergence postcraniotomy hypertension. A prospective, randomized open labeled clinical trial was designed to compare the incidence of breakthrough hypertension (systolic blood pressure [SBP] > 140 mm Hg) and adverse effects (hypotension, tachycardia, and bradycardia) between the two drug combinations. Secondarily, the effects of the drugs on SBP, mean blood pressure, and diastolic blood pressure were evaluated over the course of the study. Forty-two patients received enalaprilat 1.25 mg IV at dural closure followed by either multidose nicardipine 2 mg IV or labetalol 5 mg IV to maintain the SBP below 140 mm Hg. SBP was similarly controlled in both groups. There was a marginally smaller incidence of failures and adverse effects with labetalol. Blood pressure profiles were similar for both groups.
Abstract: The purpose of this study was to measure the effect of flow triggering (FT), added to pressure support ventilation (PSV), during spontaneous breathing in intubated patients.
Abstract: The methanol-burning lung model has been used as a technique for generating a predictable ratio of carbon dioxide production (VCO2) to oxygen consumption (VO2) or respiratory quotient (RQ). Although an accurate RQ can be generated, quantitatively predictable and adjustable VO2 and VCO2 cannot be generated. We describe a new burner device in which the combustion rate of methanol is always equal to the infusion rate of fuel over an extended range of O2 concentrations. This permits the assembly of a methanol-burning lung model that is usable with O2 concentrations up to 100% and provides continuously adjustable and quantitative VO2 (69-1,525 ml/min) and VCO2 (46-1,016 ml/min) at a RQ of 0.667.
Abstract: Transfusion of allogeneic blood is associated with risks of human immunodeficiency virus and hepatitis transmission, transfusion reactions, and other potential immunologic and infectious complications. To determine if predonation of autologous blood impacts upon transfusion practice and clinical outcome following liver resection, clinical records of 379 consecutive patients undergoing hepatic resection for metastases of colorectal cancer were identified from the prospective hepatobiliary database and reviewed.
Abstract: The preoperative cardiopulmonary risk index (CPRI) is a multifactorial index intended to predict postoperative outcome after thoracic surgery. It combines cardiac and pulmonary information into one parameter that ranges from 1 to 10, with 10 being the worst. A CPRI > or = 4 has been advocated as an effective predictor of postoperative pulmonary and cardiac complications. This study prospectively evaluates the predictive value of CPRI in a large population of patients undergoing thoracic surgery.
Abstract: We have previously demonstrated that maintenance of a low central venous pressure (LCVP) combined with extrahepatic control of venous outflow reduced the overall blood loss during major hepatic resections. This study examined the overall outcomes and, in particular, renal morbidity associated with a large series of consecutive major liver resections performed with this approach. In addition, the rationale for the anesthetic management to maintain LCVP was carefully reviewed.
Abstract: This study was designed to develop an accurate preoperative index of prediction of outcome and hospital charges after lung resection with standard available pulmonary tests in a tertiary cancer center.
Abstract: A test designed to separate those undergoing thoracic surgery without complications and those with complications must be both highly specific and sensitive. Clearly, the difference between patients at opposite ends of the population curves is easy to identify. Spirometry can be helpful for screening, although it is not a very discriminating test. If patients fall in the overlap region between the populations, however, it is impossible to discern the risks with any certainty using low-yield tests. A test with higher sensitivity, specificity, and predictive values is necessary to ascertain such marginal differences. With this kind of analysis at hand, preoperative testing can be divided into three predictive value groups. Calculating the predictive value of each preoperative test can provide a comparative measure of usefulness of discriminative power (Table 1). In this way, spirometry, blood gas analysis, and stair climbing tolerance are shown to be poor predictors of outcome. An intermediate predictive value can be achieved using diffusion capacity, exercise-induced decreases in O2 saturation, and exercise PVR. High predictive value can be accomplished with combination indexes (PPP, possibly PRQ), measurement of VO2 at 40 watts of exercise, or VO2max. Logic dictates a step-wise preoperative evaluation using prediction value analysis (Fig.4). A flow decision chart for the preoperative evaluation of patients for pulmonary resection begins with exercise oximetry, spirometry, and blood gas analysis as general screening tests to separate those patients at minimal or no risks for complications from those patients that require further evaluation. Functional indexes (PPP, PRQ) or exercise testing can aid further in the selection of those patients in whom a nonsurgical option should be considered. Flow decision chart for the preoperative evaluation of patients for pulmonary resection should continue to evolve as new information about outcome studies is gathered. Examination of outcome data will provide us with reduction of the size of the nonoperable population, so that we can deny only those patients who truly pose a prohibitive risk.
Abstract: Hepatic resection is prone to significant blood loss. Adverse effects of blood loss and transfusion mandate improvements in surgical techniques to reduce blood loss and transfusion requirements.
Abstract: Anesthesiologists spend much of their time administering anesthesia to children outside of the operating room, especially for neuroradiological evaluation. Neuroradiological procedures include magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography, myelography, pneumoencephalography, and arteriography. Each of these procedures presents a "working environment" that compromises the ability to deliver a safe and well-monitored anesthetic (1). CT-guided stereotactic brain biopsy in children requires two anesthetic locations (2). The stereotactic guidance apparatus renders the airway inaccessible both during CT and during transport to the operating room. We report a case of a child undergoing CT-guided stereotactic brain biopsy to elucidate the anesthetic considerations of this logistically difficult procedure.
Abstract: We undertook this study to characterize the postthoracotomy compartmental displacement and respiratory mechanical changes occurring during and after the performance of the incentive spirometry maneuver. We also evaluated the effect of recumbency angle on compartmental recruitment. Sixteen patients were randomized to perform incentive spirometry either at 30 degrees or 60 degrees recumbency angle. They were studied using respiratory inductance plethysmography to measure tidal volume, respiratory frequency, inspiratory time, rib cage motion/tidal volume ratio, inspiratory duty cycle, and inspiratory flow. Patients were studied before surgery and on postoperative days 1 and 3. Statistical analysis was accomplished using multiple measures ANOVA with post-hoc Student's t-tests when appropriate. Preoperative incentive spirometry augmented VT by increasing both VT/TI and TI. Postoperatively, the incentive recruitment of VT was reduced, a result of a decrease in TI and TI/TTOT; VT/TI was unchanged. There was postoperative decrease of AB and AB/VT during incentive spirometry, greatest in the 60 degrees group. Our results characterize the nature of the respiratory recruitment afforded by incentive spirometry, before and after thoracotomy. We also found evidence of postthoracotomy diaphragmatic derecruitment during incentive spirometry exacerbated by a high recumbency angle.
Abstract: As survival and quality of life continue to improve for cardiac transplant recipients, there is an ever-increasing possibility that these patients will present for elective and/or emergency surgery outside of a transplantation center. Cyclosporine therapy has been a major factor in extending homograft survival, but recent studies have suggested that cyclosporine administration increases the duration of action of some anesthetics. The authors evaluated the influence on anesthetic management of cardiac transplantation and chronic cyclosporine therapy in a retrospective review of all postcardiac transplant patients who presented for noncardiac surgery at the study institution. The data suggest that a number of commonly used anesthetic techniques can be administered safely to these patients when no evidence of graft rejection is present. No clinically significant prolongation of anesthetic effect was encountered following the doses of anesthetics described.
Abstract: Esmolol has been used to improve hemodynamic stability during sternotomy and aortic manipulation for coronary artery bypass graft surgery. In order to investigate the alterations of esmolol metabolism by hypothermic cardiopulmonary bypass (CPB), the effect of temperature on the metabolism of esmolol in vitro was determined. Samples of human whole blood were combined with esmolol solution (50 micrograms/mL in 0.9 mol/L NaCl) and incubated at 4 degrees C, 15 degrees C, 25 degrees C, and 37 degrees C. Aliquots were sampled at 1, 5, 10, 15, 30, 60, and 120 minutes; esmolol concentration was determined using high-pressure liquid chromatography. There was a temperature-dependent decrease in the degradation of esmolol. The half-life for esmolol in human blood was 19.6 +/- 3.8 minutes at 37 degrees C, 47 +/- 10.1 minutes at 25 degrees C, 152 +/- 46.6 minutes at 15 degrees C, and 226.7 +/- 60.1 minutes at 4 degrees C. This study clearly shows marked reduction of esmolol metabolism with hypothermia possibly leading to persistent beta-adrenergic blockade following the discontinuation of CPB. Persistent beta-blockade may provide additional protection to the ischemic myocardium during hypothermic arrest and/or result in difficulty in weaning from CPB.
Abstract: Thoracic epidural fentanyl has been used successfully for postoperative analgesia in patients undergoing thoracic surgery. Prior investigators have suggested that increasing the administered dosage and volume of lumbar epidural fentanyl may increase the spread of analgesia. The feasibility of injecting a high volume (20 mL) of fentanyl into the lumbar epidural space for post-thoracic surgery analgesia was studied in 17 patients undergoing elective thoracotomy or sternotomy. All patients had a lumbar epidural catheter placed before induction of general anesthesia. No narcotic was administered during surgery. Thirty minutes before the conclusion of anesthesia, 200 micrograms of fentanyl in 16 mL of 0.9% saline was administered via the epidural route. In the intensive care unit (ICU), additional fentanyl in the same dosage and volume was injected when the patient complained of pain. Pain was scored on a linear analog scale pre-injection and 30 minutes post-injection. Arterial blood gases were obtained simultaneously. All patients experienced pain relief within 15 minutes of injection. No significant respiratory depression or hypercarbia was noted. Lumbar epidural fentanyl is a safe and practical alternative to thoracic epidural analgesia in the post-thoracic surgical patient.
