Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Clinical TrialThe influence of nicardipine-, nitroglycerin-, and prostaglandin E(1)-induced hypotension on cerebral pressure autoregulation in adult patients during propofol-fentanyl anesthesia.
We investigated the influence of drug-induced hypotension at a mean arterial pressure (MAP) of 60-70 mm Hg on cerebral pressure autoregulation in 45 adult patients during propofol-fentanyl anesthesia. Time-averaged mean blood flow velocity in the right middle cerebral artery (Vmca) was continuously measured at a PaCO(2) of 39-40 mm Hg by using transcranial Doppler ultrasonography. Hypotension was induced and maintained with a continuous infusion of nicardipine, nitroglycerin, or prostaglandin E(1). Cerebral autoregulation was tested by a slow continuous infusion of phenylephrine to induce an increase in MAP of 20-30 mm Hg. From the simultaneously recorded data of Vmca and MAP, cerebral vascular resistance (CVR) was calculated as MAP/Vmca. Furthermore, the index of autoregulation (IOR) was calculated as DeltaCVR/DeltaMAP, where DeltaCVR = change in CVR and DeltaMAP = change in MAP. The test was performed twice for each condition on each patient: baseline and hypotension. The IOR during baseline was similar among the groups. During nitroglycerin- and prostaglandin E(1)-induced hypotension, IOR was not different from baseline. In contrast, during nicardipine-induced hypotension, IOR significantly decreased compared with baseline (0.37 +/- 0.08 versus 0.83 +/- 0.07, P < 0.01). In conclusion, nicardipine, but not nitroglycerin or prostaglandin E(1), significantly attenuates cerebral pressure autoregulation during propofol-fentanyl anesthesia. ⋯ Vasodilators may influence cerebral autoregulation by changing cerebral vascular tone. Nicardipine, but not nitroglycerin or prostaglandin E(1), attenuated cerebral pressure autoregulation in normal adult patients during propofol-fentanyl anesthesia.
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Anesthesia and analgesia · Jan 2002
Ambulatory discharge after long-acting peripheral nerve blockade: 2382 blocks with ropivacaine.
Discharging patients with a long-acting peripheral nerve block remains controversial. Concerns about accidental injury of the limb or surgical site because of an insensate extremity are common despite a lack of data on the subject. We report a study examining the efficacy and complications of discharge after long-acting block. This prospective study included 1791 patients receiving an upper or lower extremity nerve block with 0.5% ropivacaine and discharged the day of surgery. Efficacy (conversion to general anesthesia and opioid use), persistent motor or sensory weakness, complications, satisfaction, and unscheduled health care visits were assessed in the postanesthesia care unit (PACU) and at 24 h and 7 days postoperatively using a detailed questionnaire. There were 2382 blocks placed: 1119 upper extremity blocks and 1263 lower extremity blocks. Efficacy was demonstrated by a small conversion to general anesthesia (1%-6%) and a lack of patients requiring opioids in the PACU (89%-92%). A large percentage of patients continued to use opioids at 7 days (17%-22%). Despite the requirement for opioids, satisfaction with the anesthesia experience was high at 24 h and 7 days (Liekert scale [1-5] mean at 24 h, 4.88 +/- 0.44; mean at 7 days, 4.77 +/- 0.69) and most (98%) would choose the same anesthetic again. Thirty-seven patients (1.6%) were identified with symptoms or complaints at 7 days. After review, 6 of them (0.25%) had a persistent paresthesia that may have been related to the block or discharge. We conclude that long-acting peripheral nerve blockade may be safely used in the ambulatory setting with a high degree of efficacy, safety, and satisfaction. This technique is associated with an infrequent incidence of neurologic complications and injuries. Given the frequent incidence of persistent pain at 7 days, prolongation of the analgesia would be beneficial. ⋯ This study demonstrates that long-acting peripheral nerve blockade may be safely used in the ambulatory setting with a high degree of efficacy and satisfaction. This technique is associated with an infrequent incidence of neurologic complications and injuries despite discharge with an insensate extremity. The frequent incidence of pain at 7 days suggests that longer-acting local anesthetics are still needed.
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Anesthesia and analgesia · Jan 2002
Calculating a potential increase in hospital margin for elective surgery by changing operating room time allocations or increasing nursing staffing to permit completion of more cases: a case study.
Administrators routinely seek to increase contribution margin (revenue minus variable costs) to better cover fixed costs, provide indigent care, and meet other community service responsibilities. Hospitals with high operating room (OR) utilizations can allocate OR time for elective surgery to surgeons based partly on their contribution margins per hour of OR time. This applies particularly when OR caseload is limited by nursing recruitment. From a hospital's annual accounting data for elective cases, we calculated the following for each surgeon's patients: variable costs for the entire hospitalization or outpatient visit, revenues, hours of OR time, hours of regular ward time, and hours of intensive care unit (ICU) time. The contribution margin per hour of OR time varied more than 1000% among surgeons. Linear programming showed that reallocating OR time among surgeons could increase the overall hospital contribution margin for elective surgery by 7.1%. This was not achieved simply by taking OR time from surgeons with the smallest contribution margins per OR hour and giving it to the surgeons with the largest contribution margins per OR hour because different surgeons used differing amounts of hospital ward and ICU time. We conclude that to achieve substantive improvement in a hospital's perioperative financial performance despite restrictions on available OR, hospital ward, or ICU time, contribution margin per OR hour should be considered (perhaps along with OR utilization) when OR time is allocated. ⋯ For hospitals where elective surgery caseload is limited by nursing recruitment, to increase one surgeon's operating room time either another surgeon's time must be decreased, nurses need to be paid a premium for working longer hours, or higher-priced "traveling" nurses can be contracted. Linear programming was performed using Microsoft Excel to estimate the effect of each of these interventions on hospital contribution margin.
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Clinical TrialAlkalinization of intracuff lidocaine improves endotracheal tube-induced emergence phenomena.
We sought to evaluate the effect of filling an endotracheal tube cuff with 40 mg lidocaine alone (Group L) or alkalinized lidocaine (Group LB) in comparison to an Air Control group (Group C) on adverse emergence phenomena in a randomized controlled study (n = 25 in each group). The incidence of sore throat was decreased for Group LB in comparison to Group L during the 24 postextubation hours. The difference between Group L and Group C remained significant in the two postextubation hours only. Plasma lidocaine levels increased when lidocaine was alkalinized (C(max) were 62.5 +/- 34.0 ng/mL and 3.2 +/- 1.0 ng/mL for Groups LB and L, respectively). Cough and restlessness before tracheal extubation were decreased in Group LB compared with Group L and in Group L compared with Group C. Nausea, postoperative vomiting, dysphonia, and hoarseness were increased after extubation in Group C compared with the liquid groups, and a better tolerance was recorded with Group LB compared with Group L. The increase of arterial blood pressure and cardiac frequencies during the extubation period was less in the liquid groups than in the control group and less in Group LB compared with Group L. We concluded that use of intracuff alkalinized lidocaine is an effective adjunct to endotracheal intubation. ⋯ Use of 40 mg of alkalinized lidocaine, rather than lidocaine or air, to fill the endotracheal tube cuff reduces the incidence of sore throat in the postoperative period. This approach also decreases hemodynamic effects, restlessness, dysphonia, and hoarseness.
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Anesthesia and analgesia · Jan 2002
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of three doses of a commercially prepared oral midazolam syrup in children.
Midazolam is widely used as a preanesthetic medication for children. Prior studies have used extemporaneous formulations to disguise the bitter taste of IV midazolam and to improve patient acceptance, but with unknown bioavailability. In this prospective, randomized, double-blinded study we examined the efficacy, safety, and taste acceptability of three doses (0.25, 0.5, and 1.0 mg/kg, up to a maximum of 20 mg) of commercially prepared Versed((R)) syrup (midazolam HCl) in children stratified by age (6 mo to <2 yr, 2 to <6 yr, and 6 to <16 yr). All children were ASA class I-III scheduled for elective surgery. Subjects were continuously observed and monitored with pulse oximetry. Ninety-five percent of patients accepted the syrup, and 97% demonstrated satisfactory sedation before induction. There was an apparent relationship between dose and onset of sedation and anxiolysis (P < 0.01). Eight-eight percent had satisfactory anxiety ratings at the time of attempted separation from parents, and 86% had satisfactory anxiety ratings at face mask application. The youngest age group recovered earlier than the two older age groups (P < 0.001). There was no relationship between midazolam dose and duration of postanesthesia care unit stay. Before induction, there were no episodes of desaturation, but there were two episodes of nausea and three episodes of emesis. At the time of induction, during anesthesia, and in the postanesthesia care unit, there were several adverse respiratory events. Oral midazolam syrup is effective for producing sedation and anxiolysis at a dose of 0.25 mg/kg, with minimal effects on respiration and oxygen saturation even when administered at doses as large as 1.0 mg/kg (maximum, 20 mg) as the sole sedating medication to healthy children in a supervised clinical setting. ⋯ Commercially prepared oral midazolam syrup is effective in producing sedation and anxiolysis in doses as small as 0.25 mg/kg; there is a slightly faster onset with increasing the dose to 1.0 mg/kg. At all doses, 97% of patients demonstrated satisfactory sedation, whereas 86% demonstrated satisfactory anxiolysis when the face mask was applied.