Synthesis and proton NMR spectroscopy of intra-vesicular gamma-aminobutyric acid (GABA).

We report the synthesis of vesicles containing gamma-aminobutyric acid (GABA), and their proton nuclear magnetic resonance ((1)H NMR) spectra. These vesicles were constructed to more closely mimic the intracellular environment wherein GABA exists. For this study, these GABA-containing vesicles were examined under (1)H NMR as a potential platform for future studies on the differences between aqueous phantoms, ex vivo brain extracts, and in vivo magnetic resonance spectroscopy results. We found that intra-vesicular GABA faithfully yielded the chemical shifts and J-coupling constants of free aqueous GABA, alongside the chemical shift signals of the vesicle wall.

A retrospective study of intraoperative awareness with methodological implications.

BACKGROUND: Awareness during general anesthesia is a problem receiving increased attention from physicians and patients. Large multicentered studies have established an accepted incidence of awareness during general anesthesia as approximately 1-2 per 1000 cases or 0.15%. More recent retrospective data, however, suggest that the actual incidence may be as low as 0.0068%. METHODS: To assess the incidence of awareness at our institution, we conducted a review of adult patients undergoing surgical procedures over a 3-year period. Information on awareness came from entries of "Intraoperative Awareness" captured during our standard evaluations on postoperative day one in our perioperative information system. Patients were not questioned specifically about awareness. RESULTS: We reviewed 116,478 charts; 65,061 patients received general anesthesia and 51,417 received other types of anesthesia. Of the patients receiving general anesthesia, 44,006 had complete postoperative documentation. The reported incidence of undesired intraoperative awareness in this population was 10/44,006 (1/4401 or 0.023%). Of the patients who received other anesthetic modalities, 22,885 had complete postoperative documentation. Undesired intraoperative awareness was reported in 7/22,885 patients who did not receive general anesthesia (1/3269 or 0.03%). The reported incidence of intraoperative awareness was not statistically different between the two groups (P = 0.54). Relative risk of intraoperative awareness during a general anesthetic compared with a nongeneral anesthetic was 0.74, with 95% confidence interval [0.28, 2.0]. CONCLUSION: Using a retrospective methodology, reports of intraoperative awareness are not statistically different in patients who received general anesthesia compared with those who did not. These results suggest that, despite success with other rare perioperative events, the resolution of retrospective database analyses may be too low to study intraoperative awareness.

The extended Mallampati score and a diagnosis of diabetes mellitus are predictors of difficult laryngoscopy in the morbidly obese.

BACKGROUND: The modified Mallampati (MMP) classification is a standard method of oropharyngeal evaluation for predicting difficult laryngoscopy. Previous studies have demonstrated that the predictive value of the MMP is improved when the patient's craniocervical junction is extended rather than neutral (Extended Mallampati Score, EMS). In the present study, we compared the predictive value of the MMP and EMS in the morbidly obese. METHODS: We performed a prospective study of adult patients with a Body Mass Index (BMI) > or = 40 over a 12-mo period comparing the MMP and EMS. The performance of the MMP, EMS, and other commonly used tests was compared for the ability to predict difficult laryngoscopy, defined as a Cormack-Lehane grade of 3 or 4. Positioning and direct laryngoscopic techniques were not standardized. The incidence of difficult laryngoscopy and difficult intubation was compared in patients with BMI > or = or < 40. RESULTS: Three-hundred-forty-six patients with a BMI > or = 40 were evaluated with both the MMP and EMS and received direct laryngoscopy. On average, craniocervical extension decreased the MMP class (P < 0.0001). Compared to the MMP, the EMS improved specificity and predictive value while maintaining sensitivity. Compared to the MMP and other tests, an EMS class of 3 or 4 and a diagnosis of diabetes mellitus were the only statistically significant predictors of difficult laryngoscopy in the morbidly obese. There was no difference in the incidence of difficult laryngoscopy or intubation in the morbidly obese compared to patients with a BMI < 40. CONCLUSIONS: The EMS was superior to the MMP in the prediction of difficult laryngoscopy in the morbidly obese population. A diagnosis of diabetes mellitus also warrants further investigation as a predictor of difficult laryngoscopy in this population. Finally, this study supports previous findings that morbid obesity is not itself a predictor of difficult laryngoscopy or intubation.

A rare case of anti-Hu paraneoplastic neurologic syndrome in association with cervical cancer.

Anti-Hu antibodies, also known as ANNA-1, are well characterized in paraneoplastic neuropathies. We present here the first known case of anti-Hu seropositivity, cerebellar ataxia, and sensory neuropathy in association with cervical cancer.

Cardiac arrhythmias following anesthesia induction in infantile-onset Pompe disease: a case series.

BACKGROUND: Patients with infantile-onset Pompe disease suffer from marked hypertrophic cardiomyopathy and an increased risk of arrhythmia. A noncompliant left ventricle predisposes these infants to diastolic heart failure with elevated left ventricular enddiastolic pressure (LVEDP); these patients also commonly develop systolic heart failure. Given this baseline cardiac physiology, coronary perfusion pressure becomes highly sensitive to abrupt changes in diastolic blood pressure (DBP). METHODS: We retrospectively reviewed the experiences of 139 patients enrolled in clinical trials investigating the treatment of infantile-onset Pompe disease with recombinant human acid alpha-glucosidase (rhGAA). Adverse events were screened for those involving anesthesia. RESULTS: Nine patients (6%) with infantile-onset Pompe disease experienced an arrhythmia or cardiopulmonary arrest soon after the induction of general anesthesia. Of these events, propofol was involved in four arrhythmias; sevoflurane without propofol was associated with an additional two. Deaths resulting from arrhythmia appeared to correlate with left ventricular mass indices >350 g x m(-2). CONCLUSIONS: With the advent of enzyme replacement therapy (ERT) using rhGAA, and increased survivability, more infantile Pompe patients will likely present for surgical procedures. Additional care in maximizing coronary perfusion pressure and minimizing arrhythmia risk must be given. For these reasons, it is recommended that anesthesia for infantile Pompe patients specifically avoid propofol or high concentrations of sevoflurane and, instead, use an agent such as ketamine as the cornerstone for induction in order to better support coronary perfusion pressure and to avoid decreasing DBP with vasodilatory agents.

Statistical models of acute mountain sickness.

Acute mountain sickness (AMS) is caused by exposure to altitudes exceeding 2500 m and often resolves by acclimatization without further ascent. Statistical models of AMS score and the probability of an AMS diagnosis were developed to allow the combination of dissimilar exposures for simultaneous analysis. The study population was 302 trekkers from a previous investigation who provided self-reported symptoms upon arrival at 3840 m during hikes through altitudes of 1500 to 6200 m. AMS score (Hackett scale) was estimated by linear regression and the probability of an AMS diagnosis (Lake Louise criteria) by logistic regression. AMS score or probability was significantly associated with exposure day and altitude. Increased altitude over the prior 3 days resulted in higher estimated AMS score or probability and decreased altitude in lower score or probability. The odds ratio (OR) of AMS was 3.6 if not on acetazolamide. Females appeared slightly more susceptible than males (1.5 OR). The approach offers the advantages of (1) improved statistical power by combining exposures, (2) insight into the dose-response relationship of altitude exposure and AMS risk, (3) quantitative tests for the significance of factors that might affect AMS susceptibility, and (4) practical tools to track individual climbers and plan operational ascents.