Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Clinical TrialEsmolol and anesthetic requirement for loss of responsiveness during propofol anesthesia.
The administration of esmolol decreases the propofol blood concentration, preventing movement after skin incision during propofol/morphine/nitrous oxide anesthesia. However, interaction with esmolol has not been tested when propofol is infused alone. Accordingly, we tested the hypothesis that esmolol decreases the propofol blood concentration, preventing response to command (CP50-awake) when propofol is infused alone in healthy patients presenting for minor surgery. With approval and consent, we studied 30 healthy patients, who were randomized to esmolol bolus (1 mg/kg) and then infusion (250 microg x kg(-1) x min(-1)) or placebo. Five minutes later, a target-controlled infusion of propofol was commenced. Ten minutes later, responsiveness was assessed by a blinded observer. Oxygen saturation, heart rate, and noninvasive arterial blood pressure were recorded every 2 min. Arterial blood samples were taken at 5 and 10 min of propofol infusion for propofol assay. Results were analyzed with a generalized linear regression model: P <0.05 was considered statistically significant. The probability of response to command decreased with increasing propofol blood concentration (CP50-awake = 3.42 microg/mL). Esmolol did not alter the relative risk of response to command. We conclude that the previously observed effect of esmolol on propofol CP50 was not caused by an interaction between these two drugs. ⋯ There is no evidence to suggest that esmolol, an ultra-short-acting cardioselective beta-blocker, affects anesthetic requirement for loss of responsiveness during propofol anesthesia.
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Comparative Study Clinical TrialThe assessment of postural stability after ambulatory anesthesia: a comparison of desflurane with propofol.
We designed this study to evaluate postural stability in outpatients after either desflurane or propofol anesthesia. After IRB approval, 120 consenting women undergoing gynecological laparoscopic procedures were randomly assigned to receive either desflurane or propofol-based general anesthesia. After surgery, patients' postural stability was measured as body sway velocity by using a computerized force platform in the following conditions: 1) standing on a firm surface with eyes open versus closed and 2) standing on a foam surface with eyes open versus closed. These measurements were made before anesthesia, immediately after the patient achieved a Post-Anesthesia Discharge Score of 9, and at actual discharge home. At the time patients first achieved a Post-Anesthesia Discharge Score of 9, the body sway in the Propofol group was significantly more than in the Desflurane group when patients were asked to stand on a foam surface with eyes closed (testing the ability of using vestibular information for balance control). We concluded that the desflurane-based anesthetic was associated with better postural control than the propofol-based anesthetic in the early recovery period after outpatient gynecological laparoscopic procedures. ⋯ The residual effects of the short-acting general anesthetics desflurane and propofol on patient's balance function during recovery after surgery were assessed with a computerized force platform. The results showed that desflurane seemed to be associated with better postural control than propofol in the early recovery period.
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Anesthesia and analgesia · Jan 2002
Differences in pulse oximetry technology can affect detection of sleep-disorderd breathing in children.
Newer pulse oximeters have been developed to be motion resistant and thus have few false alarms. However, they have not yet been evaluated in a pediatric sleep laboratory setting. While evaluating new oximeters for use in our laboratory, we obtained simultaneous pulse oximetry data from two Masimo oximeters and from two Nellcor oximeters during nocturnal polysomnography in children referred for sleep-disordered breathing (SDB). In series 1, comprising 24 patients, comparisons were made between a Masimo oximeter with 4-second averaging time and the Nellcor N-200 oximeter set for 3 to 5 second averaging. A maximum of 20 events per patient were randomly selected for analysis, an "event" being a desaturation of > or = 4% registered by either oximeter. Interobserver agreement for event classification was 93%. Eighty-eight percent of 220 desaturation events occurring during wakefulness and 38% of 194 events occurring during sleep were classified as motion artifact on the Nellcor oximeter. Neither the Masimo oximeter nor the transcutaneous oxygen probe confirmed that the desaturation was real, in most of these cases. During sleep, there were 119 events detected by either or both oximeters: 113 (95%) by the Nellcor versus 82 (69%) by the Masimo. For these 119 events, the extent of desaturation was slightly less for the Masimo than the Nellcor oximeter, 4.5 +/- 2.4% versus 5.5 +/- 2.5%, respectively. In series 2, 22 patients were studied comparing a Masimo Radical oximeter with 2 second averaging to the Nellcor N-200 oximeter. The extent of desaturation was slightly greater for the Masimo oximeter. The Masimo oximeter detected more non-artifactual desaturation events occurring during sleep than the Nellcor oximeter, 90% versus 76% (chi2 = 9.9, p < 0.01). In series 3, comprising 128 events in 5 patients, a Nellcor N-395 oximeter detected fewer desaturations during non-movement, sleep periods and had more movement related "desaturation" events, compared to a Masimo Radical oximeter. ⋯ The Masimo oximeters register many fewer false desaturations due to motion artifact. Using 4-second averaging, a Masimo oximeter detected significantly fewer SaO2 dips than the Nellcor N-200 oximeter but using 2-second averaging, the Masimo oximeter detected more SaO2 dips than the Nellcor N-200 oximeter. The sensitivity and motion artifact rejection characteristics of the Nellcor N-395 oximeter are not adequate for a pediatric sleep laboratory setting. These findings suggest that in a pediatric sleep laboratory, use of a Masimo oximeter with very short averaging time could significantly reduce workload and improve reliability of desaturation detection.
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Anesthesia and analgesia · Jan 2002
Colostrum morphine concentrations during postcesarean intravenous patient-controlled analgesia.
Patient-controlled analgesia (PCA) with morphine is a convenient method for providing postoperative analgesia. Despite the fact that it is used after cesarean delivery, data on transfer of morphine and of its active metabolite morphine-6 glucuronide (M6G) into maternal milk are scarce. It is not known whether breast-feeding during PCA with morphine has neonatal implications. We sought to measure morphine and M6G concentrations in colostrum during postpartum IV PCA and evaluate the potential for drug intake by neonates being breast-fed by these mothers. Seven informed and consenting mothers, given IV PCA with morphine, were investigated. Plasma and milk samples were obtained at titration, and at 12, 24, 36, and 48 h. Morphine and M6G were measured by high-performance liquid chromatography. In plasma, morphine concentrations ranged from <1 to 274 ng/mL, M6G ranged from <5 to 974 ng/mL. In milk, opioids were found in only 3 patients in whom morphine concentrations ranged from <1 to 48 ng/mL and M6G from <5 to 1084 ng/mL. The milk-to-plasma ratio was always <1 for morphine. In conclusion, we observed very small morphine and M6G concentrations in colostrum during PCA with morphine. Under these conditions, the amounts of drug likely to be transferred to the breast-fed neonate are negligible. ⋯ Colostrum concentrations of morphine and its active metabolite morphine-6 glucuronide were measured in mothers receiving patient-controlled analgesia with morphine after cesarean delivery. The concentrations were found to be very small, thus supporting the safety of breast-feeding in mothers receiving IV patient-controlled analgesia with morphine.
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Opening of the first door of pulse photometry gave us pulse oximeter. The next door opens to multiwavelength pulse photometry. It will give us a high performance pulse oximeter, providing a wide variety of clinical information simultaneously. This next generation of pulse photometry should further improve bedside monitoring and patient care.