In utero Exposure to Anesthetics Alters Neuronal Migration Pattern in Developing Cerebral Cortex and Causes Postnatal Behavioral Deficits in Rats.

During fetal development, cerebral cortical neurons are generated in the proliferative zone along the ventricles and then migrate to their final positions. To examine the impact of in utero exposure to anesthetics on neuronal migration, we injected pregnant rats with bromodeoxyuridine to label fetal neurons generated at embryonic Day (E) 17 and then randomized these rats to 9 different groups receiving 3 different means of anesthesia (oxygen/control, propofol, isoflurane) for 3 exposure durations (20, 50, 120 min). Histological analysis of brains from 54 pups revealed that significant number of neurons in anesthetized animals failed to acquire their correct cortical position and remained dispersed within inappropriate cortical layers and/or adjacent white matter. Behavioral testing of 86 littermates pointed to abnormalities that correspond to the aberrations in the brain areas that are specifically developing during the E17. In the second set of experiments, fetal brains exposed to isoflurane at E16 had diminished expression of the reelin and glutamic acid decarboxylase 67, proteins critical for neuronal migration. Together, these results call for cautious use of anesthetics during the neuronal migration period in pregnancy and more comprehensive investigation of neurodevelopmental consequences for the fetus and possible consequences later in life.

Bronchospasm during cardiopulmonary bypass. Etiology and management.

Severe bronchospasm occurring after extracorporeal circulation is an unusual event. We report three such cases. Possible etiologies include activation of complement anaphylatoxins during cardiopulmonary bypass, cardiac asthma, cold urticaria syndrome, exacerbation of preoperative bronchospastic disease, allergic reactions, drug-induced histamine release and beta-adrenergic blockade induced bronchospasm. The management and treatment of patients with this complication is reviewed.

Differential effects of advanced age on neurologic and cardiac risks of coronary artery operations.

Two thousand patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were prospectively studied to compare the influence of age on the incidence of neurologic, cardiac, and other complications. Postoperative neurologic events were found in 56 (2.8%) patients, with an incidence in patients > or = 75 years (8.9%) more than twice that of patients 65 to 74 (3.6%) and nine times larger than in patients < 65 (0.9%). Cardiac complications did not differ between age groups except for low cardiac output state, which occurred 1.7 times more frequently in patients > or = 75 years compared with those < 65. Patients with postoperative neurologic events had a ninefold increase in mortality--35.7% versus 4.0%. Logistic regression analysis demonstrate the most important predictors of a postoperative neurologic event to be age, preoperative neurologic abnormality, recent myocardial infarction, and duration of cardiopulmonary bypass. The risk of neurologic complications increases disproportionately to the risk of cardiac complications in the elderly undergoing coronary artery bypass grafting with cardiopulmonary bypass. Despite neurologic improvement (32 of 56 patients), a postoperative neurologic event was second only to low cardiac output state as the postoperative complication most highly associated with in-hospital death. These results are important for decisions regarding selection of candidates for coronary artery bypass grafting and for prediction of surgical outcome.

Morbidity and duration of ICU stay after cardiac surgery. A model for preoperative risk assessment.

Although risk factors for mortality after cardiac surgery have been identified, there is no widely applicable method for readily determining risk of postoperative morbidity based on preoperative severity of illness. The goal of this study was to develop a model for stratifying the risk of serious morbidity after adult cardiac surgery using readily available and objective clinical data. After univariate analysis of risk factors in 3,156 operations, 11 variables were identified as important predictors by logistic regression (LR) analysis and used to construct an additive model to calculate the probability of serious morbidity. Reliable correlation was found between a simplified additive model for clinical use and the LR model. The clinical and logistic models were then tested prospectively in 394 patients and demonstrated a pattern of increasing morbidity with ascending scores similar to that predicted by the reference group. Increasing clinical risk score was also associated with a greater frequency of individual complications as well as prolongation of ICU stay. This study demonstrates that it is feasible to design a simple method to stratify the risk of serious morbidity after adult cardiac surgery. With further prospective multicenter refinement and testing, such a model is likely to be useful for adjusting severity of illness when reporting outcome statistics as well as planning resource utilization.

Minimal positive end-expiratory pressure (PEEP) may be "best PEEP".

In the absence of clinical trials, positive end-expired pressure (PEEP) has been accepted as efficacious for treatment of postoperative decreases in arterial oxygen tension (PaO2) from a variety of causes including adult respiratory distress syndrome (ARDS). PEEP is thought to increase PaO2 by alveolar recruitment, which in turn, has been hypothesized to play a decisive role in pulmonary recovery. One hundred and eighteen patients were followed prospectively, and after development of decreased PaO2, randomized to receive recruitive PEEP (determined by blood gas criteria) or supportive PEEP (the minimal PEEP required to maintain PaO2 above 60 mm Hg on .5 inspired O2 fraction (FIO2). No prognostic factors were significantly different between the two groups. Recruitive PEEP application in 22 patients yielded a significantly increased incidence of hypotension (55 percent), pneumothorax (20 percent), and death during treatment (27 percent) when compared to the 28 supportive PEEP patients who had no hypotension or pneumothorax and only one death during treatment (4 percent). After PEEP treatment, deaths in each group were similar (19 percent and 15 percent, respectively). We find no evidence that PEEP treatment promotes beneficial outcomes and conclude that recruitment attempts may be harmful.

Cardiorespiratory effects of venous air embolism in dogs receiving a perfluorocarbon emulsion.

The cardiorespiratory effects of a nonlethal venous air embolism were studied in dogs in the presence of a perfluorocarbon emulsion (PFE). Prior to embolization, five dogs received 20 cc/kg of hydroxyethyl starch (6% HES) and five received PFE oxypherol (20% FC-43). Determinations of mean systemic arterial pressure (MAP), pulmonary artery pressure (PAP), left ventricular pressure (LVP), first and second derivatives of LVP with respect to time (dP/dt and Vmax), cardiac index (CI), stroke index, left and right ventricular stroke work index (LVSWI and RVSWI), PaCO2, PaO2, and venous admixture (Qs/Qt) were made before and then 1, 5, 10, and 30 minutes after placement of the venous air emboli (0.75 cc/kg/min for 5 minutes). After emboli were introduced, PaO2, MAP, LVSWI, dP/dt, Vmax, and CI decreased; the average decrease during the first 5 minutes was significantly less in the PFE group. Following introduction of venous air emboli, PAP, PaCO2, RVSWI, and Qs/Qt increased less in the PFE group than in the HES group, with statistical significance achieved at various times during the first 10 minutes after embolism. All parameters returned toward baseline values by 30 minutes in both groups. This study indicates that FC-43, when administered before venous air embolism, helps to attenuate some of the detrimental cardiorespiratory effects of the embolism.

Perioperative myocardial infarction.

POMI can occur during all types of cardiac surgery, but is most common during coronary artery surgery. Although the causes of POMI are usually multifactorial, an understanding of these causes provides the clinician a better basis for developing strategies to prevent as well as treat this complication. POMI usually results in a benign postoperative course, but can contribute to intra- or postoperative death, postoperative low cardiac output syndrome, as well as diminished long-term exercise tolerance and survival. These latter events highlight the importance of POMI after cardiac surgery and depend on the extent and location of the infarct as well as the functionality of the remaining viable myocardium. Future advances in surgical, medical, and anesthetic management will be necessary to further decrease the incidence and severity of POMI so as to afford patients the best chance of survival and a productive life after heart surgery.

Transient radicular irritation after hyperbaric lidocaine spinal anesthesia in parturients.

Two cases of transient radicular irritation in pregnant patients are presented. Both cases involve the combination of spinal anesthesia employing hyperbaric 5% lidocaine and a small gauge pencilpoint needle as well as the surgery being performed in the lithotomy position. We recommend that until the potential for lidocaine-induced neuroradicular irritation under these circumstances is evaluated prospectively, hyperbaric lidocaine should not be used for cases in which a small gauge spinal needle is employed and the patient is placed in the lithotomy position.

High-cost, high-tech medicine: are we getting our money's worth?

Increasingly stringent fiscal restraints on the spending for health care, driven by the scarcity of health resources, has introduced a need to apply cost containment measures to nearly all aspects of medical care. Intelligent cost containment measures must include application of disciplined logic to the decision making process of when to use high-tech, high-cost interventions. Such decision making depends upon knowledge of the basic concepts of economic and cost-benefit analyses, outcome (benefit) studies, and some principles of decision-threshold analysis. These basic principles are reviewed, and the potential impact of application of strategies for cost containment in the operating room and the intensive care unit is discussed.

The incidence of venous air embolism during total hip arthroplasty.

Venous air embolism has been reported to occur during total hip arthroplasty. The incidence of venous air embolism, however, has not been previously studied in a large series using Doppler ultrasound and mass spectrometry. Seventy patients undergoing total hip arthroplasty were monitored for venous air embolism with precordial Doppler ultrasound, central venous catheter, end-tidal N2 and CO2 (mass spectrometry), and arterial blood gases (ABG). Changes in the monitored variables consistent with venous air embolism were noted in 57% by Doppler ultrasound, 9% by mass spectrometry, 4% by central venous catheter and 3% of the cases by ABG. A total of 77 Doppler ultrasound events were detected in 40 of the 70 patients studied. Hemodynamic changes consisting of either hypotension, defined as a greater than or equal to 20% decrease in mean arterial pressure (MAP), or cardiac dysrhythmia occurred during 43% of these events. The Doppler ultrasound was the only monitor that detected all cases of venous air embolism with concomitant hemodynamic changes. Air was aspirated from the central venous catheter during 10% of the detections of venous air embolism by Doppler ultrasound. Venous air embolism in total hip arthroplasty is a common event and may be responsible for hemodynamic changes previously ascribed to the use of methylmethacrylate cement. Routine monitoring with Doppler ultrasound appears warranted. The routine use of central venous catheterization may also be warranted.

Does functional ability in the postoperative period differ between remifentanil- and fentanyl-based anesthesia?

STUDY OBJECTIVES: To compare patients' functional ability in the 24-hour postoperative period following a remifentanil compared to a hypnotic-fentanyl-treated anesthesia regimen using a 24-Hour Functional Ability Questionnaire. DESIGN: Prospective, 1:1 single-blind, randomized, controlled effectiveness study. SETTING: Multicenter study including 156 hospitals and ambulatory surgery facilities. PATIENTS: 2438 patients (1496 outpatients and 942 inpatients) 18 years of age or older, scheduled for elective surgeries under general endotracheal anesthesia, with an expected duration of unconsciousness of > or =30 minutes. INTERVENTIONS: Patients were randomized to receive either intravenous remifentanil (0.5 microg/kg/min for induction and intubation; with the infusion rate decreased to 0.25 microg/kg/min after intubation) or fentanyl (administered according to anesthesiologists' usual practice) as the opioid during surgery. Concomitant hypnotic drugs were propofol and/or isoflurane (with or without nitrous oxide) titrated according to protocol. Transition analgesia with either morphine or fentanyl was given in the remifentanil patients and at the discretion of the anesthesiologists in the fentanyl patients. MEASUREMENTS: A validated set of measurements of functional ability, rather than more traditional clinical psychological methods, to compare the recovery of patients from remifentanil- and fentanyl-treated anesthetic regimens up to 24 hours after surgery. MAIN RESULTS: Remifentanil was statistically superior to fentanyl for the four functional assessments evaluated: walking without dizziness, thinking clearly, concentration, and communicating effectively. These differences reflect events occurring within the first 24 hours after anesthesia and surgery. CONCLUSIONS: A remifentanil-treated anesthetic demonstrated earlier return to some functions than a fentanyl-treated technique. Although functional assessment is a field that is still in its infancy, a questionnaire to assess functional ability during the 24 hours after anesthesia may provide more practical information about anesthetic recovery than previously used, traditional psychomotor evaluations.

The impact of liver transplant programs on anesthesia personnel and services.

Liver transplantation procedures are being performed at an increasing number of hospitals throughout the United States. These procedures are challenging because of hemodynamic, metabolic, renal, and coagulation dysfunctions and may require prolonged periods of time for completion. Anesthesia departments are developing or managing teams of personnel to perform liver transplants. A survey was sent to directors of liver transplant anesthesia teams to investigate how teams were structured, compensated, and the impact of participation upon personnel involved. Thirty-nine centers were surveyed and 31 responded. The results showed an arithmetic doubling of cases for each of the last six years, most being performed at large medical centers (more than 759 beds) with populations served of 2 million or more. Cases were reported to average 13 hours in length and required a mean of five anesthesia personnel to complete. Compensation methods for work on a liver transplant team were variable; however, CRNAs and technicians received monetary reimbursement more frequently than physicians. Emotional responses of personnel were equally divided between favorable and unfavorable responses. Discriminate analysis showed that positive personnel attitudes were most closely tied to the presence of a protocol for breaks, call schedules, compensation, and the frequency of performing these cases. However, most protocols for personnel management were instituted in response to dissatisfaction. As the number of transplants per year increases, departments will need effective plans for personnel management to maximize departmental resources, increase research interest, and maintain personnel enthusiasm.

Monitoring hemostasis.

As our understanding of the normal mechanisms of coagulation grows, so does our ability to monitor hemostasis. Evaluation of hemostasis will become more specific and accurate and instrumentation techniques will become simpler and more efficient as technology progress, facilitating the monitoring of hemostasis in the perioperative setting.

Peripheral vascular surgery: does anesthetic management affect outcome?

Several recent articles have examined the effect of anesthetic technique on outcome in patients undergoing peripheral vascular surgery. This review examines the recent literature and evaluates the role of new data in advancing current understanding of the impact of anesthetic management on outcome in this high-risk population.

Pulmonary thromboembolism during liver transplantation: possible association with antifibrinolytic drugs and novel treatment options.

The authors describe two cases of massive intraoperative pulmonary thromboembolism resulting in cardiovascular collapse during liver transplantation. The potential role of antifibrinolytic drugs is discussed, along with the use of treatment modalities not previously applied in this setting.