Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
High-dose caffeine suppresses postoperative apnea in former preterm infants.
Thirty-two former preterm infants (less than or equal to 44 weeks postconceptual age) undergoing inguinal hernia repair were prospectively studied. General inhalational anesthesia with neuromuscular blockade was used. No barbiturates or opioids were given. ⋯ Fifty percent of the patients had SpO2 less than 90% at the time. This study shows that iv caffeine 10 mg/kg is effective in the control of apnea in otherwise healthy expremature infants between 37 and 44 weeks of postconceptual age. It is still recommended, however, that all infants at risk be monitored for at least 12 h for apnea and bradycardia following general anesthesia.
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Comparative Study Clinical Trial Controlled Clinical Trial
Mivacurium-induced neuromuscular blockade following single bolus doses and with continuous infusion during either balanced or enflurane anesthesia.
Mivacurium chloride (BW B1090U) was administered to 72 patients during their elective surgery. The eight groups (nine subjects per cell) in the 2 x 2 x 2 study design differed in three factors: the size of the mivacurium bolus dose administered, whether or not this dose was followed by an infusion of mivacurium, and in the technique used for the maintenance of anesthesia. Four groups received a single bolus dose of mivacurium, 0.15 mg/kg, and the remaining four groups received mivacurium, 0.25 mg/kg, administered iv in 15 s. ⋯ Four groups, again two at each bolus dose, subsequently received an infusion of mivacurium, adjusted to depress the twitch response by approximately 95%. Infusion rates averaged 6.0 micrograms.kg-1.min-1 in the groups receiving balanced anesthesia and 4.2 micrograms.kg-1.min-1 for those receiving enflurane anesthesia. Recovery following administration by infusion was slower than that observed following a bolus dose of mivacurium, 0.15 mg/kg but did not differ between the anesthetic groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Comparative Study Clinical Trial
Perioperative pulmonary function in acute respiratory failure: effect of ventilator type and gas mixture.
Whether maintaining pulmonary nitrogenation and/or a stable ventilatory pattern during surgery would minimize changes in perioperative pulmonary function in two groups of patients with acute respiratory failure (ARF) whose lungs were being mechanically ventilated was examined. Group 1 (n = 39 cases) (inspired oxygen fraction [FIO2] less than or equal to 0.5, minute ventilation less than or equal to 15 l/min, peak inspiratory pressure less than or equal to 50 cmH2O, positive end-expiratory pressure [PEEP] less than or equal to 10 cmH2O) were assigned randomly to one of four intraoperative ventilator-gas mixture (FIO2 approximately 0.5) combinations: 1) Siemens 900C ventilator, N2/O2; 2) Siemens 900C ventilator, N2O/O2; 3) Ohio anesthesia ventilator, N2/O2; or 4) Ohio anesthesia ventilator, N2O/O2. Group 2 (n = 15 cases) (ventilatory requirements exceeding any of those in Group 1) had their lungs ventilated intraoperatively with the Siemens 900C ventilator and a gas mixture determined by their anesthesiologist (FIO2 approximately 0.6-1.0). ⋯ In patients whose lungs were ventilated with the Ohio N2/O2 combination, PaO2/FIO2 decreased significantly from 270 +/- 86 mmHg preoperatively to 174 +/- 74 mmHg intraoperatively. These variables did not change significantly in patients ventilated with the Siemens ventilator (groups 1 and 2). Pulmonary oxygen gas exchange returned to preoperative values by the first hour postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Pharmacokinetics and dynamics of intravenous, intrathecal, and epidural clonidine in sheep.
Epidural clonidine administration produces analgesia by a spinal action but may produce hemodynamic depression by activating other central or peripheral alpha 2-adrenoceptors. To determine clonidine's distribution and cardiorespiratory effects 300 micrograms clonidine was injected epidurally, intrathecally, and intravenously in six chronically prepared sheep, and cerebrospinal fluid (CSF) and arterial plasma clonidine were measured. Dural transfer of epidurally administered clonidine was rapid and extensive: time to maximal concentration (Tmax) in CSF was 32 +/- 8 min, bioavailability in CSF was 14 +/- 4% of the administered dose, and maximal CSF concentrations following epidural administration (820 +/- 30 ng/ml) were three orders of magnitude greater than those following iv injection (0.71 +/- 0.06 ng/ml). ⋯ Blood pressure increased and heart rate decreased following iv injection when plasma clonidine concentrations were high (greater than 2 ng/ml). Clonidine, following all routes of administration, numerically decreased blood pressure, but this decrease was significant only following epidural (mean arterial pressure = 97 +/- 6 mmHg before, 86 +/- 6 mmHg after; P less than 0.05) and intrathecal (93 +/- 9 mmHg before, 79 +/- 10 mmHg after; P less than 0.05) injection. Blood pressure decreased earlier following intrathecal than following epidural injection, corresponding with higher CSF clonidine concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)