Acute spontaneous coronary artery dissection in the peripartum period.
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Biomedical subjects
Publications and source records attributed to Peter L Bailey.
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The Bispectral Index (BIS) is a processed electroencephalogram, which has been evaluated as an automated monitoring technique for patients receiving sedation for endoscopic procedures. BIS monitoring has not been shown to be of significant clinical benefit, but the need for an objective quantitative measure of the depth of sedation in patients undergoing endoscopy remains.
Pulmonary artery catheterization is associated with numerous complications, including serious arrhythmias. We report a case where ventricular tachycardia occurred repeatedly during attempted pulmonary artery catheterization, precluding successful catheterization. Transesophageal echocardiography was used to image the tricuspid valve and right ventricle and revealed a Sinus of Valsalva aneurysm protruding significantly into the right ventricle and obstructing advancement of the pulmonary artery catheter. Our case reveals another identifiable cause of serious arrhythmia during pulmonary artery catheterization and highlights how transesophageal echocardiography can be useful in unanticipated ways during cardiac anesthesia and surgery.
We simulated needle paths based on the central landmark used for central venous catheterization of the internal jugular vein. We obtained ultrasound images to quantify the landmark's accuracy (precision and bias) in 107 subjects placed in Trendelenburg position with their heads turned 30-35 degrees. We also determined the frequency of simulated carotid artery puncture. The simulated needle path missed the middle 80% of the lumen of the internal jugular vein in 34% of subjects (95% confidence interval [CI], 25% to 44%) and traversed the carotid artery in 26% of subjects (95% CI, 18% to 35%). Both events occurred in 20% of subjects (95% CI, 13%-29%). The landmark had a medial bias of 3.7 mm (95% CI, 2.7 to 4.8); it was more often (77 of 104 subjects) medial to the center of the right internal jugular vein (P < 0.001). The landmark was more likely to miss the internal jugular vein (odds ratio, 3.11; P < 0.016) and intersect the carotid (odds ratio, 3.03; P < 0.024) in obese patients. The central landmark should not be expected to yield frequent success on first needle pass without risk of carotid puncture because of its imprecision and bias. The measured bias should be considered when the central landmark is used for central venous catheterization.
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The administration of sedation/analgesia to allow patients to tolerate diagnostic or therapeutic procedures and tests is a fact of life. Approximately 200,000,000 such sedations are administered every year in the United States. Any morbidity or mortality associated with sedation is likely to be deemed avoidable. There will never be adequate resources or personnel so that trained anesthesia providers administer all sedations, and there probably is no need for such an approach. Clinicians from many specialties now safely and effectively administer sedation. With attention to updated guidelines and concepts, as outlined in this article, the safety and efficacy of sedation/analgesia can and should be excellent.
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BACKGROUND: Traditional methods of assessing ventilatory effects of sedative agents do not measure their propensity to cause upper airway obstruction (UAO). The primary objective of this study was to develop a method, using dynamic negative airway pressure (DNAP), for replicating UAO during deep sedation. METHODS: A state of deep sedation (defined as an Observer Assessment of Alertness and Sedation score of 3 and a bispectral index < 80) was attained in 10 healthy volunteers, aged 19-41, using midazolam. Volunteers breathed through a chamber connected to a regulated source of negative pressure that was gradually adjusted downward to produce UAO based on maximal inspiratory flow. The study consisted of three phases: A control phase while awake, a study phase during midazolam deep sedation, and a recovery phase after flumazenil administration. RESULTS: During the control phase no subject demonstrated airway obstruction at negative pressures to -30-cm H2O. All subjects exhibited complete UAO during DNAP episodes while sedated. Negative pressures required to cause complete UAO (Pcrit) ranged from -2 to -14 cm H2O. After administration of flumazenil, all subjects attained full consciousness within 5 min and did not demonstrate UAO at negative pressures to -30-cm H2O. CONCLUSIONS: Dynamic Negative Airway Pressure is a useful method for provoking midazolam-induced UAO, and may potentially be used to compare the potential for different sedatives and patient factors to cause UAO. Flumazenil was completely effective in reversing the potential for midazolam to cause UAO.
BACKGROUND: Because propofol is water insoluble, current formulations of propofol use a soybean oil emulsion. These soybean emulsions cause elevated plasma triglycerides and support bacterial growth. This study compares an alternative formulation of propofol as a 2% emulsion in a medium-chain triglyceride solution (IDD-D Propofol) with Diprivan. METHODS: This double-blind, crossover, phase 1 study compared IDD-D Propofol with Diprivan using two consecutive protocols of 12 subjects each. Subjects in protocol 1 received a single bolus of 2.5 mg/kg, and those in protocol 2 received the same induction dose followed by a 30-min infusion at 0.2 mg. kg(-1).min(-1). Venous samples were taken for propofol concentration and biochemical measurements. Induction and emergence times were measured by termination of voluntary counting and responding to command, respectively. RESULTS: Plasma concentrations were not different between the two formulations. Induction time was 14% longer with IDD-D Propofol than with Diprivan (N = 24, protocols 1 and 2 combined, 53.3 +/- 12.1 s and 46.9 +/- 7.8 s, respectively; P = 0.002). Emergence time was not significantly different for protocol 1 but was marginally longer (P = 0.04) for IDD-D Propofol in protocol 2 (1,197 +/- 445 s [n = 11] and 1,254 +/- 468 s [n = 12], respectively). As expected because of the inherent characteristics of the formulations, plasma triglycerides were elevated for Diprivan but not for IDD-D Propofol; octanoate, a metabolite of medium-chain triglycerides, was elevated only with IDD-D Propofol. Octanoate was elevated to concentrations below those considered toxic. Plasma concentrations of other biochemical markers of medium-chain triglyceride metabolism, ketones, showed no significant changes. Interestingly, there were significant differences between male and female subjects in the propofol plasma concentrations and time to awakening with both drugs. CONCLUSIONS: Differences between the two propofol formulations were slight and not clinically significant. Similar gender differences in plasma concentrations and awaking times were found for both formulations.