Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialThe effect of intraoperative use of esmolol and nicardipine on recovery after ambulatory surgery.
There is controversy regarding the optimal technique for maintaining hemodynamic stability during anesthesia. We designed this prospective, randomized, double-blinded study to test the hypothesis that the technique used for maintaining hemodynamic stability during general anesthesia can influence recovery after ambulatory surgery. Forty-five healthy consenting women undergoing gynecologic laparoscopy procedures were randomly assigned to 1 of 3 treatment groups: Group 1 (control, n = 15) received normal saline 5 mL and 1 mL, followed by a saline infusion at a rate of 0.005 mL x kg(-1) x min(-1); Group 2 (n = 15) received esmolol 50 mg and saline 1 mL, followed by an esmolol infusion 5 microg x kg(-1) x min(-1); and Group 3 (n = 15) received esmolol 50 mg and nicardipine 1 mg, followed by an esmolol infusion 5 microg x kg(-1) x min(-1). The study drugs were administered after the induction of anesthesia with fentanyl 1.5 microg/kg, and propofol 2 mg/kg I.V. Tracheal intubation was facilitated with vecuronium 0.12 mg/kg I.V. Anesthesia was initially maintained with desflurane 2% end-tidal and N(2)O 67% in oxygen in all 3 groups. During surgery, the mean arterial blood pressure (MAP) was maintained within +/-15% of the baseline value by varying the study drug infusion rate and the inspired concentration of desflurane. In addition to MAP and heart rate values, electroencephalogram bispectral index values were recorded throughout the perioperative period. Recovery times and postoperative side effects were assessed. Compared with the control group, adjunctive use of esmolol and nicardipine attenuated the increase in heart rate (in Group 2) and MAP (in Group 3) after tracheal intubation. Furthermore, the use of an esmolol infusion as an adjunct to desflurane to control the acute autonomic responses during the maintenance period significantly decreased emergence times (4 +/- 2 versus 7 +/- 4 min), decreased the need for postoperative opioid analgesics (43% versus 80%), and reduced the time to discharge (209 +/- 89 versus 269 +/- 100 min). We conclude that the adjunctive use of esmolol alone or in combination with nicardipine during the induction of anesthesia reduced the hemodynamic response to tracheal intubation. Furthermore, use of an esmolol infusion as an adjuvant to desflurane-N(2)O anesthesia for controlling the acute hemodynamic responses during the maintenance period improved the recovery profile after outpatient laparoscopic surgery. ⋯ The adjunctive use of the beta-adrenergic blocker esmolol to control the acute sympathetic responses during desflurane-based anesthesia provided a more rapid awakening from anesthesia, reduced the postoperative opioid analgesic requirement, and decreased the time to discharge home after ambulatory laparoscopic surgery.
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Anesthesia and analgesia · Dec 2003
Estimating alveolar dead space from the arterial to end-tidal CO(2) gradient: a modeling analysis.
Using an original, validated, high-fidelity model of pulmonary physiology, we compared the arterial to end-tidal CO(2) gradient divided by the arterial CO(2) tension (Pa-E'CO(2)/PaCO(2)) with alveolar dead space expressed as a fraction of alveolar tidal volume, calculated in the conventional manner using Fowler's technique and the Bohr equation: (VDalv/VTalv)(Bohr-Fowler). We examined the variability of Pa-E'CO(2)/PaCO(2) and of (VDalv/VTalv)(Bohr-Fowler) in the presence of three ventilation-perfusion defects while varying CO(2) production (Vdot;CO(2)), venous admixture, and anatomical dead space fraction (VDanat). Pa-E'CO(2)/PaCO(2) was approximately 59.5% of (VDalv/VTalv)(Bohr-Fowler). During constant alveolar configuration, the factors examined (Vdot;CO(2), pulmonary shunt fraction, and VDanat) each caused variation in (VDalv/VTalv)(Bohr-Fowler) and in Pa-E'CO(2)/PaCO(2). Induced variation was slightly larger for Pa-E'CO(2)/PaCO(2) during changes in VDanat, but was similar during variation of venous admixture and Vdot;CO(2). Pa-E'CO(2)/PaCO(2) may be a useful serial measurement in the critically ill patient because all the necessary data are easily obtained and calculation is significantly simpler than for (VDalv/VTalv)(Bohr-Fowler). ⋯ Using an original, validated, high-fidelity model of pulmonary physiology, we have demonstrated that the arterial to end-tidal carbon dioxide pressure gradient may be used to robustly and accurately quantify alveolar dead space. After clinical validation, its use could replace that of conventionally calculated alveolar dead space fraction, particularly in the critically ill.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialPreincisional treatment to prevent pain after ambulatory hernia surgery.
We designed this study as a randomized comparison of postoperative pain after inguinal hernia repair in patients treated with triple preincisional analgesic therapy versus standard care. Triple therapy consisted of a nonsteroidal antiinflammatory, a local anesthetic field block, and an N-methyl-D-aspartate inhibitor before incision. The treatment group (n = 17) received rofecoxib, 50 mg PO, a field block with 0.25% bupivacaine/0.5% lidocaine, and ketamine 0.2 mg/kg IV before incision; controls (n = 17) received a placebo PO before surgery. The anesthetic protocol was standardized. Postoperative pain was treated by fentanyl IV and oxycodone 5 mg/acetaminophen 325 mg PO as required for pain. Pain scores (0-10) and analgesic were recorded for the first 7 days after surgery. Pain scores were 47% lower in the treatment group before discharge (3.1 +/- 0.6 versus 5.9 +/- 0.6, P = 0.0026) (mean +/- SE) and 18% less in the first 24 h after discharge (5.6 +/- 0.4 versus 6.8 +/- 0.5, P = 0.05); oral analgesic use was 34% less in the treatment group (4.6 +/- 0.8 doses versus 7.1 +/- 0.7 doses, P = 0.02) in the first 24 h after surgery. We conclude that triple preincisional therapy diminishes pain and analgesic use after outpatient hernia repair, and encourage further evaluation of this technique. ⋯ Outpatients undergoing inguinal hernia repair under general anesthesia report moderate-to-severe pain after surgery. Triple preincisional therapy that included rofecoxib, 50 mg PO, ketamine, 0.2 mg/kg IV, and local anesthetic field block reduced pain scores and analgesic use in the first 24 h after discharge.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialOptimizing the dose of intrathecal morphine in older patients undergoing hip arthroplasty.
Intrathecal (IT) morphine provides excellent postoperative analgesia but may result in many side effects, including postoperative nausea and vomiting, pruritus, and respiratory depression, particularly at larger doses. Older patients may be at particular risk. The optimal dose of spinal morphine in older patients undergoing hip arthroplasty is not known. We designed this prospective, randomized, controlled, double-blinded study to evaluate the analgesic efficacy and side effect profile of 50-200 microg of IT morphine in older patients undergoing elective hip arthroplasty. Sixty patients older than 65 years undergoing elective hip arthroplasty were enrolled. Patients were randomized to receive spinal anesthesia with 15 mg of bupivacaine and IT morphine in four groups: 1). 0 microg, 2). 50 microg, 3). 100 microg, and 4). 200 microg. IT morphine 100 and 200 microg produced effective pain relief and decreased the postoperative requirement for morphine compared with control. IT morphine 50 microg did not provide effective pain relief. Both 100 and 200 microg of IT morphine provided comparable levels of postoperative analgesia. There were no between-group differences in postoperative nausea and vomiting, sedation, respiratory depression, or urinary retention. Pruritus was significantly more frequent with 200 microg of IT morphine. In conclusion, 100 microg of IT morphine provided the best balance between analgesic efficacy and side effect profile in older patients undergoing hip arthroplasty. ⋯ The dosage of intrathecal morphine that provides the best balance between analgesic efficacy and side effect profile in the older patient undergoing hip arthroplasty is not known. This prospective, randomized, controlled, double-blinded clinical trial demonstrates that a dose of 100 microg of intrathecal morphine provides the best balance between efficacy and side effects, compared with doses of 0, 50, and 200 microg of morphine, in this patient population.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of antiemetics on pupillary reflex dilation during epidural/general anesthesia.
The effect of dopamine D2 receptor antagonists, such as chlorpromazine and haloperidol, on pupil size in awake subjects suggests that these drugs might also alter pupillary reflex dilation and pupil size during general anesthesia. Forty-seven patients undergoing lower abdominal surgery under combined epidural/general anesthesia were randomized to receive one of the 5 following open labeled drugs: 10 mL saline, 0.13 mg/kg ondansetron, 0.25 mg/kg metoclopramide, 0.5 mg/kg metoclopramide, or 0.02 mg/kg droperidol. Three measurements of reflex dilation were taken at 5-min intervals and after the last measurement (time 0) the drug was administered. Measurements were then taken 5, 10, 20, and 40 min after I.V. drug administration. Reflex dilation was induced by intermittent noxious stimulation of the C5 dermatome with a tetanic electric current (60-70 mamp, 100 Hz, 3-s duration) after a stable level of epidural analgesia had been established with 3/8% bupivacaine and maintained with a continuous infusion. Metoclopramide produced a small decrease in pupil diameter and transiently depressed reflex dilation, whereas droperidol decreased pupil size at 10 min and depressed reflex dilation throughout the 40-min study period. Maximal change in reflex dilation was -6.6 +/- 3.3 mm-sec after droperidol. Ondansetron had no effect on pupil diameter or reflex dilation. When pupillary diameter measurements are used to gauge opioid levels during experimental conditions or during surgical anesthesia, antiemetic medication acting on the dopamine D2 receptor should be avoided. ⋯ Miosis is often considered an effect of opioid administration during general anesthesia, but other drugs, such as antiemetics, might produce a similar effect on the pupil. This study demonstrates that 2 antiemetics, droperidol and metoclopramide, constrict the pupil and block the pupillary dilation brought about by nociceptive stimuli.