Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2004
Randomized Controlled Trial Clinical TrialProphylactic phenylephrine infusion for preventing hypotension during spinal anesthesia for cesarean delivery.
In a randomized, double-blinded, controlled trial, we investigated the prophylactic infusion of IV phenylephrine for the prevention of hypotension during spinal anesthesia for cesarean delivery. Immediately after intrathecal injection, phenylephrine was infused at 100 microg/min (n = 26) for 3 min. From that point until delivery, phenylephrine was infused at 100 microg/min whenever systolic arterial blood pressure (SAP), measured each minute, was less than baseline. A control group (n = 24) received IV bolus phenylephrine 100 microg after each measurement of SAP <80% of baseline. Phenylephrine infusion decreased the incidence (6 [23%] of 26 versus 21 [88%] of 24; P < 0.0001), frequency, and magnitude (median minimum SAP, 106 mm Hg; interquartile range, 95-111 mm Hg; versus median, 80 mm Hg; range, 73-93 mm Hg; P < 0.0001) of hypotension compared with control. Heart rate was significantly slower over time in the infusion group compared with the control group (P < 0.0001). Despite a large total dose of phenylephrine administered to the infusion group compared with the control group (median, 1260 microg; interquartile range, 1010-1640 microg; versus median, 450 microg; interquartile range, 300-750 microg; P < 0.0001), umbilical cord blood gases and Apgar scores were similar. One patient in each group had umbilical arterial pH <7.2. Prophylactic phenylephrine infusion is a simple, safe, and effective method of maintaining arterial blood pressure during spinal anesthesia for cesarean delivery. ⋯ In patients receiving spinal anesthesia for elective cesarean delivery, a prophylactic infusion of phenylephrine 100 microg/min decreased the incidence, frequency, and magnitude of hypotension with equivalent neonatal outcome compared with a control group receiving IV bolus phenylephrine.
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Anesthesia and analgesia · Mar 2004
Randomized Controlled Trial Clinical TrialProphylactic treatment with desmopressin does not reduce postoperative bleeding after coronary surgery in patients treated with aspirin before surgery.
The synthetic vasopressin analog desmopressin has hemostatic properties and may reduce postoperative bleeding after coronary artery bypass grafting (CABG). A study on the effects of recent aspirin ingestion on platelet function in cardiac surgery showed a greater impairment of platelet function in patients treated with aspirin <2 days before the operation. We evaluated the effects of desmopressin on postoperative bleeding in CABG patients who were treated with aspirin 75 or 160 mg until the day before surgery. The study was a prospective, randomized, double-blinded, placebo-controlled, parallel group trial. One-hundred patients were included and divided into two groups. One group received desmopressin 0.3 micro g/kg and the other received placebo (0.9% NaCl) after the neutralization of heparin with protamine sulfate. Postoperative blood loss was recorded for 16 h. The mean (SD) bleeding was 606 (237) mL in the desmopressin group and 601 (301) mL in the placebo group (P = 0.93), representing no significant difference (95% confidence interval, -107 to 117 mL). We conclude that desmopressin does not reduce postoperative bleeding in CABG patients treated with aspirin until the day before surgery. ⋯ Continuation of aspirin until the day before coronary artery bypass grafting may increase postoperative bleeding. The administration of desmopressin to these patients after the neutralization of heparin with protamine sulfate does not reduce postoperative bleeding.
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Anesthesia and analgesia · Mar 2004
Randomized Controlled Trial Comparative Study Clinical TrialNarcotrend index versus bispectral index as electroencephalogram measures of anesthetic drug effect during propofol anesthesia.
The Narcotrend monitor (MonitorTechnik, Bad Bramstedt, Germany) performs an automatic analysis of the electroencephalogram (EEG) during anesthesia based on a visual assessment of the raw EEG. Its newest software version 4.0 includes a dimensionless index that, similar to the bispectral index (BIS), ranges from 100 (awake) to 0. We compared the performance of Narcotrend index and BIS as EEG measures of anesthetic drug effect during propofol anesthesia. Eighteen adult patients scheduled for radical prostatectomy were investigated. An epidural catheter was placed in the lumbar space and electrodes for BIS (version XP; Aspect Medical Systems, Natick, MA) and Narcotrend were positioned as recommended by the manufacturers. Narcotrend index, BIS values, and propofol plasma and effect site concentrations as parallelly simulated by Rugloop software (Department of Anesthesia, Ghent University, Belgium) were automatically recorded in intervals of 5 s. Induction of anesthesia consisted of a fentanyl bolus and a propofol infusion. After endotracheal intubation, patients received 15 mL bupivacaine 0.5% epidurally, and 45 min later propofol dosages were subsequently increased and decreased twice. Simulated propofol effect site concentrations ranged from 2.0 +/- 0.4 microg/mL (smallest) to 6.3 +/- 1.3 microg/mL (largest) during these subsequent increases and decreases of propofol. In terms of prediction probability (P(K)) the performance of the Narcotrend index (P(K) = 0.88 +/- 0.03) to predict propofol effect site concentrations was comparable to the BIS (P(K) = 0.85 +/- 0.04). Using the respective EEG index as a measure of drug effect the mean k(e0) was calculated as 0.20 +/- 0.05 min(-1) for Narcotrend index and 0.16 +/- 0.07 min(-1) for BIS. In the observed propofol concentration range Narcotrend index detected differences in EEG dynamics as well as BIS. ⋯ This study in 18 adult patients undergoing radical prostatectomy describes the relationship between Narcotrend index and bispectral index versus predicted propofol effect compartment concentrations. In terms of prediction probability, the performance of the Narcotrend index and the bispectral index to predict propofol effect site concentrations was comparable.
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Anesthesia and analgesia · Mar 2004
Randomized Controlled Trial Clinical TrialThe effects of different ventilatory settings on pulmonary and systemic inflammatory responses during major surgery.
Mechanical ventilation with high tidal volumes (V(T)) and zero or low positive end-expiratory pressure increased mediator release to inflammatory stimuli or acute lung injury. We studied whether mechanical ventilation modifies the inflammatory responses during major thoracic or abdominal surgery. Sixty-four patients undergoing elective thoracotomy (n = 34) or laparotomy (n = 30) were randomized to receive either mechanical ventilation with V(T) = 12 or 15 mL/kg ideal body weight, respectively, and zero end-expiratory pressure, or V(T) = 6 mL/kg ideal body weight with positive end-expiratory pressure of 10 cm H(2)O. In 62 patients who completed the study, arterial oxygenation was not different between groups. Tumor necrosis factor, interleukin (IL)-1, IL-6, IL-8, IL-10, and IL-12 were determined by cytometric bead array in plasma after 0, 1, 2, and 3 h and in tracheal aspirates after 3 h of mechanical ventilation. Data were log-transformed and analyzed using parametric or nonparametric tests, as indicated. All plasma mediators increased more during abdominal than during thoracic surgery, although the differences were small. However, neither time course nor concentrations of pulmonary or systemic mediators differed between the two ventilatory settings. Our data suggest that the ventilatory settings we studied do not affect inflammatory reactions during major surgery within 3 h. ⋯ In 62 patients undergoing elective major thoracic or abdominal surgery, mechanical ventilation with low tidal volumes and positive end-expiratory pressure or high tidal volumes and zero end-expiratory pressure did not result in different pulmonary or systemic levels of measured inflammatory markers.
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Anesthesia and analgesia · Mar 2004
Comparative StudyClinical evaluation of the effects of signal integrity and saturation on data availability and accuracy of Masimo SE and Nellcor N-395 oximeters in children.
Pulse oximetry manufacturers have introduced technologies that claim improved detection of hypoxemic events. Because improvements in signal processing and data rejection algorithms may differentially affect data reporting, we compared the data reporting and signal heuristic performance and agreement among the Nellcor N-395, Masimo SET, and GE Solar 8000 oximeters under a spectrum of conditions of signal integrity and arterial oxygen saturations. A blinded side-by-side comparison of technologies was performed in 27 patients, and data were analyzed for time of data availability, measures of agreement and signal heuristics, and warnings stratified by signal integrity and SpO(2). The Solar 8000 had less total data dropout than either of the new technologies. Masimo's LoSIQ (signal quality) heuristic rejected less data than Nellcor's MOT/PS (motion/pulse search) flag. When no signal heuristic was displayed, there was little difference in precision and bias between the two newer technologies; however, agreement between devices deteriorated in the presence of SIQ, MOT, or hypoxemia. Both newer devices flagged questionable data, but their use of different rejection algorithms resulted in different probabilities of presenting data. Therefore, with poor SIQ or during hypoxemia, the Nellcor N-395 and Masimo oximeters are not clinically equivalent to each other or to the older Solar 8000 oximeter. ⋯ We compared new pulse oximeters from Nellcor and Masimo and found that, with good signal conditions, both new devices performed similarly to older technology. Overall, Masimo reported less data as questionable than Nellcor. With poor signal conditions or during hypoxemia, the new devices are not clinically equivalent to each other or to the older technology.