Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1992
Comparative StudyPreoxygenation of pregnant and nonpregnant women in the head-up versus supine position.
The influence of preoxygenation in the supine (n = 10) versus the 45 degrees head-up (n = 10) position on the duration of apnea leading to a decrease in arterial oxygen saturation to 95%, as monitored by pulse oximetry, was investigated in 20 women undergoing elective cesarean section at term of pregnancy. The results were compared with those obtained in a control group of 20 nonpregnant women. ⋯ We conclude that pregnant women desaturate their arterial blood of oxygen more rapidly than do nonpregnant women. Furthermore, the head-up position extends the duration of apnea that can take place before desaturation occurs in nonpregnant patients.
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Anesthesia and analgesia · Nov 1992
Randomized Controlled Trial Comparative Study Clinical TrialIsoflurane and nitrous oxide: comparative impact on cerebrospinal fluid pressure in patients with brain tumors.
The relative effects on cerebrospinal fluid pressure (CSFP) of equipotent concentrations of isoflurane and N2O were compared in 20 patients with brain tumors who had lumbar subarachnoid catheters in place. Patients were randomly assigned to receive one of two anesthetic sequences: group 1, 0.7% end-tidal isoflurane in O2, which was changed to 70% N2O in O2; or group 2, 70% N2O in O2, which was changed to 0.7% end-tidal isoflurane in O2. End-tidal PCO2 and percent end-tidal N2O and isoflurane were monitored by mass spectrometry from just before changing anesthetics (time = 0 min) until the end of a 20-min observation period (time = 20 min). ⋯ The patients in group 1 sustained an increase in CSFP that reached a maximum of 33% above the value at 0 min, despite a 3-mm Hg decrease in PaCO2 (P < 0.05). By contrast, CSFP remained unchanged in group 2. Although the absolute increase in CSFP after replacement of isoflurane/O2 by N2O/O2 anesthesia was relatively small (9 +/- 1 to 12 +/- 2 mm Hg; P < 0.05), the absence of a similar effect in patients where N2O was replaced by isoflurane suggests that replacement of isoflurane by an equipotent concentration of N2O is more likely to lead to an increase in CSFP in patients with altered intracranial dynamics than is replacement of N2O by isoflurane.
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Anesthesia and analgesia · Nov 1992
Comparative StudyComparison of two techniques to inflate the bronchial cuff of the Univent tube.
The Univent tube is an endotracheal tube with a movable bronchial blocker. The blocker cuff reportedly exhibits high-pressure characteristics when inflated to seal any adult bronchus. This study was aimed at measuring the cuff volume that would seal the bronchus when two different techniques of cuff inflation were used. ⋯ The bronchial cuff was then inflated until air bubbles ceased to appear in the beaker. Direct measurement of compliance of the blocker cuff confirmed its high-pressure characteristics. Bronchial sealing volume ranged from 3 to 5 mL when measured with the NPT and from 4 to 6 mL when measured with the PPT.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Nov 1992
Effect of partial neuromuscular blockade on intraoperative electromyography in patients undergoing resection of acoustic neuromas.
Intraoperative electromyographic monitoring of the facial nerve during acoustic neuroma excision provides early detection of nerve injury and improved outcome. To determine whether a useful level of peripheral neuromuscular blockade could be achieved without compromise of facial electromyographic monitoring, we studied 10 patients undergoing resection of acoustic neuroma. Facial nerve monitoring was accomplished by placement of wire electrodes in the orbicularis oris, orbicularis occuli, and mentalis muscles. ⋯ Decrements in facial nerve CMAPs were detected in 6 of 10 patients, and all demonstrated moderate to severe facial nerve dysfunction. In no patient was an unexpected deficit present postoperatively. Moderate degrees of peripheral neuromuscular blockade can be achieved without compromising facial nerve electromyographic monitoring.
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Anesthesia and analgesia · Nov 1992
Randomized Controlled Trial Clinical TrialEpidural patient-controlled analgesia: influence of bupivacaine and hydromorphone basal infusion on pain control after cesarean delivery.
Epidural administration of hydromorphone was evaluated using a patient-controlled analgesia (PCA) delivery system in 170 healthy women undergoing elective cesarean delivery with epidural bupivacaine who were randomly assigned to one of four epidural PCA treatment groups: group I, hydromorphone alone by bolus administration; group II, hydromorphone, with a continuous (basal) infusion; group III, hydromorphone in combination with 0.08% bupivacaine by bolus administration; or group IV, hydromorphone and bupivacaine, with a concurrent infusion of both drugs. Patients in group I required significantly less opioid medication (2.1 +/- 1.1 mg [mean +/- SD]) during the first 24 h than patients in group II (3.3 +/- 1.3 mg). ⋯ In addition, patients in all four groups had similar pain, sedation, discomfort, fatigue, and anxiety scores. The frequency of awakening at night to self-administer analgesic medication was not decreased when a basal infusion was used.(ABSTRACT TRUNCATED AT 250 WORDS)