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 Comparative Study Clinical TrialDextromethorphan-associated epidural patient-controlled analgesia provides better pain- and analgesics-sparing effects than dextromethorphan-associated intravenous patient-controlled analgesia after bone-malignancy resection: a randomized, placebo-controlled, double-blinded study.
Pain after bone malignancy surgery is intense and requires large amounts of analgesics. The augmented antinociceptive effects of dextromethorphan (DM), a N-methyl-D-aspartate receptor antagonist, were demonstrated previously. We assessed the use of postoperative patient-controlled epidural analgesia (PCEA) or IV patient-controlled analgesia (PCA) in patients undergoing surgery for bone malignancy under standardized combined general and epidural anesthesia with or without DM. Patients (n = 120) were randomly allocated to receive PCEA (ropivacaine 3.2 mg plus fentanyl 8 microg/dose) or IV-PCA (morphine 2 mg/dose) postoperatively, starting at subjective visual analog scale pain intensity >or=4 of 10 for up to 96 h. Placebo or DM 90 mg orally (30 patients/group/set) was given in a double-blinded manner before surgery and for 2 days afterwards. Diclofenac 75 mg IM was available as a rescue drug. DM patients used PCA and rated their pain >50% less than their placebo counterparts in each set, especially during the first 2 postoperative days (P < 0.01). Hourly and overall maximal pain intensity among PCEA patients was approximately 50% less than in the IV-PCA set (P < 0.01). Diclofenac was used 42% less (P < 0.01) by the PCA-DM patients compared with their placebo counterparts. Seven PCEA-DM and 11 IV-PCA-DM individuals reported having side effects compared with 44 in the PCEA-placebo and the IV-PCA-placebo groups (P < 0.01). Time to first ambulation was similar with both analgesia techniques but shorter among the DM-treated patients compared with the placebo recipients (1.5 +/- 0.8 versus 2.1 +/- 1.1 days, P = 0.02). Thus, DM afforded better pain control and reduced the demand for analgesics, augmented the PCEA effect versus IV-PCA, and was associated with minimal untoward effects in each analgesia set. DM patients ambulated earlier than placebo recipients. ⋯ Patients undergoing bone-malignancy surgery under combined general and epidural anesthesia received randomly patient-controlled epidural analgesia (PCEA) or IV patient-controlled analgesia (PCA) postoperatively and dextromethorphan (DM) 90 mg or placebo double-blindly for 3 days (n = 30/group/set). The DM effect was recorded with minimal untoward effects: it afforded better pain control and reduced the demand for analgesics compared with the placebo, especially when associated with PCEA. DM patients ambulated earlier than placebo recipients.
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Anesthesia and analgesia · Mar 2004
Clinical TrialThe intubating laryngeal mask airway facilitates tracheal intubation in the lateral position.
Although the difficulty of tracheal intubation in the lateral position has not been systematically evaluated, airway loss during surgery in a laterally positioned patient may have hazardous consequences. We explored whether the intubating laryngeal mask airway (ILMA) facilitates tracheal intubation in patients with normal airway anatomy, i.e., Mallampati grade
or=5 cm, positioned in the lateral position. We evaluated whether this technique can be used as a rescue when the airway is lost during the middle of surgery in laterally positioned patients with respect to success rate and intubation time. Anesthesia was induced with propofol, fentanyl, and vecuronium in 50 patients undergoing spine surgery for lumbar disk herniation (Lateral) and 50 undergoing other surgical procedures (Supine). Patients having disk surgery (Lateral) were positioned on their right or left sides before induction of general anesthesia, and intubation was performed in that position. Patients in the control group (Supine) were anesthetized in supine position, and intubation was performed in that position. Intubation was performed blindly via an ILMA in both groups. The time required for intubation and number and types of adjusting maneuvers used were recorded. Data were compared by the Mann-Whitney U test, Fisher's exact test, chi(2) test, or unpaired Student's t-test, as appropriate. Data presented as mean (SD). Demographic and airway measures were similar in the two groups, except for mouth opening, which was slightly wider in patients in the lateral position: 5.1 (0.9) versus 4.6 (0.7) cm. The time required for intubation was similar in each group ( approximately 25 s), as was intubation success (96%). We conclude that blind intubation via an ILMA offers a frequent success rate and a clinically acceptable intubation time (<1 min) even in the lateral position. ⋯ Blind intubation via the intubating laryngeal mask airway (ILMA) offers frequent success and a clinically acceptable intubation time even in patients in the lateral position. -
Anesthesia and analgesia · Mar 2004
The incidence and prediction of automatically detected intraoperative cardiovascular events in noncardiac surgery.
The objective of this study was to evaluate prognostic models for quality assurance purposes in predicting automatically detected intraoperative cardiovascular events (CVE) in 58458 patients undergoing noncardiac surgery. To this end, we assessed the performance of two established models for risk assessment in anesthesia, the Revised Cardiac Risk Index (RCRI) and the ASA physical status classification. We then developed two new models. CVEs were detected from the database of an electronic anesthesia record-keeping system. Logistic regression was used to build a complex and a simple predictive model. Performance of the prognostic models was assessed using analysis of discrimination and calibration. In 5249 patients (17.8%) of the evaluation (n = 29437) and 5031 patients (17.3%) of the validation cohorts (n = 29021), a minimum of one CVE was detected. CVEs were associated with significantly more frequent hospital mortality (2.1% versus 1.0%; P < 0.01). The new models demonstrated good discriminative power, with an area under the receiver operating characteristic curve (AUC) of 0.709 and 0.707 respectively. Discrimination of the ASA classification (AUC 0.647) and the RCRI (AUC 0.620) were less. Neither the two new models nor ASA classification nor the RCRI showed acceptable calibration. ASA classification and the RCRI alone both proved unsuitable for the prediction of intraoperative CVEs. ⋯ The objective of this study was to evaluate prognostic models for quality assurance purposes to predict the occurrence of automatically detected intraoperative cardiovascular events in 58,458 patients undergoing noncardiac surgery. Two newly developed models showed good discrimination but, because of reduced calibration, their clinical use is limited. The ASA physical status classification and the Revised Cardiac Risk Index are unsuitable for the prediction of intraoperative cardiovascular events.
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Anesthesia and analgesia · Mar 2004
Intracellular calcium increases in growth cones exposed to tetracaine.
Neurotoxicity of local anesthetics has been reported for both matured and growing neurons. In the present study, we examined if tetracaine increases Ca(2+) concentration during growth cone collapse. Intracellular Ca(2+) concentration was measured by fura 2/AM after exposure to tetracaine. Tetracaine (1-2 mM) induced increases in intra-growth cone Ca(2+) concentration (P < 0.01). The Ca(2+) hot spot was expanded into the neurite from the periphery towards the cell body. When tetracaine was applied to growth cones in Ca(2+) free media, the increase was minor. However, tetracaine induced growth cone collapse even in the culture media, which did not contain Ca(2+). Ni(2+) (100 microM; a general Ca(2+) channel inhibitor) and BAPTA-AM (5 microM; intracellular Ca(2+) chelator) could not inhibit growth cone collapse induced by 1-2 mM tetracaine. Tetracaine (>1 mM) induces collapse and Ca(2+) increase at growth cones simultaneously; however, these two phenomena might be provoked independently. ⋯ Tetracaine induced intracellular Ca(2+) increases and growth cone collapse in dorsal root ganglion neurons. The Ca(2+) hot spot in the growth cone expanded into the neurite from periphery towards the cell body.