Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1999
Randomized Controlled Trial Clinical TrialEpidural phenylephrine attenuates hypotension induced by alkalinized lidocaine epidural anesthesia.
In this double-blinded, randomized study, we examined the hemodynamic effects of lumbar epidural injection of alkalinized lidocaine with phenylephrine in 81 patients undergoing inguinal herniorrhaphy. Patients assigned to four equal groups received 20 mL of alkalinized lidocaine (17 mL of 2% lidocaine + 3 mL of 7% sodium bicarbonate) with one of four doses of phenylephrine: 0 (Group 1), 50 (Group 2), 100 (Group 3), or 200 microg (Group 4) injected via a lumbar epidural catheter. Blood pressure, heart rate, and skin temperature on the foot were recorded every 5 min for 1 h after injection and were compared among groups. Hypotension was defined as mean arterial pressure < 80% of baseline. The incidence of hypotension was 45%, 55%, 35%, and 15% in Groups 1-4, respectively. Patients in Group 4 showed the smallest reduction in blood pressure compared with Groups 1 and 2 (one-sided Fisher's exact test, P < 0.05). We conclude that the 200-microg dose of epidural phenylephrine (1:100,000 concentration) reduced the incidence of hypotension after epidural anesthesia with alkalinized lidocaine. ⋯ Hypotension after epidural anesthesia is common in general clinical practice. Phenylephrine administered epidurally in combination with alkalinized lidocaine may reduce the incidence of hypotension.
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Anesthesia and analgesia · Jun 1999
Randomized Controlled Trial Clinical TrialEpidural ropivacaine for the initiation of labor epidural analgesia: a dose finding study.
The purpose of our study was to determine the lowest concentration of ropivacaine that offers pain relief for the initiation of labor epidural analgesia. Women in active labor were enrolled in this prospective, randomized, double-blinded study to receive either ropivacaine 0.20% (Group I), ropivacaine 0.15% (Group II), or ropivacaine 0.10% (Group III). After placement of the epidural catheter, 13 mL of the study medication was administered. Fifteen minutes later, the adequacy of analgesia was assessed. If the woman reported that her degree of analgesia was not adequate, an additional 5 mL of the study medication was given, the degree of pain relief was reassessed 15 min later, and the study was concluded. A sequential study design was used to assess the success rates. We found that 26 of 28 (93%) women in Group I had adequate analgesia, compared with only 18 of 28 (64%) in Group II (P = 0.014) and 4 of 12 (33%) in Group III (P = 0.003). We conclude that ropivacaine 0.20% offers adequate analgesia significantly more often than either ropivacaine 0.15% or ropivacaine 0.10%. If one selects ropivacaine as the sole local anesthetic for the initiation of labor epidural analgesia, the minimal concentration should be 0.20%. ⋯ The lowest effective concentration of ropivacaine for the initiation of labor epidural analgesia has not been determined. We found that ropivacaine 0.20% offers adequate analgesia significantly more often than either ropivacaine 0.15% or ropivacaine 0.10%. If one selects ropivacaine as the sole local anesthetic for the initiation of labor epidural analgesia, the minimal concentration should be 0.20%.
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Anesthesia and analgesia · Jun 1999
Clinical TrialTissue heat content and distribution during and after cardiopulmonary bypass at 17 degrees C.
We measured afterdrop and peripheral tissue temperature distribution in eight patients cooled to approximately 17 degrees C during cardiopulmonary bypass and subsequently rewarmed to 36.5 degrees C. A nasopharyngeal probe evaluated trunk and head temperature and heat content. Peripheral tissue temperature (arm and leg temperature) and heat content were estimated using fourth-order regressions and integration over volume from 30 tissue and skin temperatures. Peripheral tissue temperature decreased to 19.7+/-0.9 degrees C during bypass and subsequently increased to 34.3+/-0.7 degrees C during 104+/-18 min of rewarming. The core-to-peripheral tissue temperature gradient was -5.9+/-0.9 degrees C at the end of cooling and 4.7+/-1.5 degrees C at the end of rewarming. The core-temperature afterdrop was 2.2+/-0.4 degrees C and lasted 89+/-15 min. It was associated with 1.1+/-0.7 degrees C peripheral warming. At the end of cooling, temperatures at the center of the upper and lower thigh were (respectively) 8.0+/-5.2 degrees C and 7.3+/-4.2 degrees C cooler than skin temperature. On completion of rewarming, tissue at the center of the upper and lower thigh were (respectively) 7.0+/-2.2 degrees C and 6.4+/-2.3 degrees C warmer than the skin. When estimated systemic heat loss was included in the calculation, redistribution accounted for 73% of the afterdrop, which is similar to the contribution observed previously in nonsurgical volunteers. ⋯ Temperature afterdrop after bypass at 17 degrees C was 2.2+/-0.4 degrees C, with approximately 73% of the decrease in core temperature resulting from core-to-peripheral redistribution of body heat. Cooling and rewarming were associated with large radial tissue temperature gradients in the thigh.
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Anesthesia and analgesia · Jun 1999
Clinical Trial Controlled Clinical TrialPostoperative analgesia with controlled-release oxycodone for outpatient anterior cruciate ligament surgery.
Reconstruction of the anterior cruciate ligament (ACL) of the knee is associated with a considerable degree of postoperative pain. Although immediate-release oral opioids are usually effective in relieving moderate to severe pain, they must be given every 4-6 h. A controlled-release (CR) formulation of oxycodone maintains therapeutic opioid concentrations for a more prolonged period, thus providing sustained pain relief. We designed this study to determine whether CR oxycodone is more effective and clinically acceptable than immediate-release oxycodone for managing pain after ambulatory ACL repair surgery. All patients received a standard general anesthetic and postoperative analgesic regimen with one of three oxycodone dosing regimens: oxycodone 10 mg every 4 h as needed, oxycodone 10 mg every 4 h, and CR oxycodone 20 mg every 12 h. Rescue analgesic consisted of oxycodone 5 mg every 6 h as needed. At 24, 36, 48, 60, and 72 h, there was a difference in pain scores among the groups (P < 0.0001); there was less pain in the CR oxycodone group. At most times, the fixed-dose group had lower pain scores than the as-needed group. The sedation scores were significantly different at 12 h (P < 0.02) and at 24, 36, 48, 60, and 72 h (P < 0.0001); the patients were more alert in the CR oxycodone group. The 72-h consumption of oxycodone was less in the CR oxycodone group (P < 0.0001). The patients had less sleep disturbance (P < 0.0001), were more satisfied (P < 0.0001), and experienced less vomiting (P < 0.02) in the CR oxycodone group compared with the other two groups. In conclusion, using CR oxycodone in the immediate 72 h after ambulatory ACL surgery provides more effective analgesia with less sedation, sleep disturbance, and postoperative vomiting compared with oxycodone prescribed on either a fixed dose or as-needed schedule. ⋯ A controlled-release formulation of oxycodone in patients undergoing anterior cruciate ligament repair on an ambulatory basis provides significant analgesic benefit and a lowering of side effects compared with either fixed-dose or as-needed oxycodone regimens.
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Anesthesia and analgesia · Jun 1999
Clinical TrialDoes the Murphy eye reduce the reliability of chest auscultation in detecting endobronchial intubation?
Bilateral breath sounds are routinely auscultated after endotracheal intubation to verify that the endotracheal tube (ETT) tip is properly positioned. We conducted the present study to ascertain whether the eye of the Murphy tube has an influence on the reliability of auscultation of breath sounds in detecting endobronchial intubation. Twenty patients undergoing scheduled oral and maxillofacial surgery participated in this study. After the induction of general anesthesia, either the Magill tube or the Murphy tube was inserted through the nose into the trachea. The fiberoptic bronchoscope was inserted through the ETT, and the distance from the nares to the carina of the trachea was measured. When breath sounds from the left side of the chest changed and disappeared while the ETT was being advanced, the distance from the nares to the ETT tip was measured. Unilateral auscultatory change was not observed until the ETT tip was advanced beyond the carina and inserted 1.5+/-0.4 cm into the right mainstem bronchus when the Magill tube was used and 2.0+/-0.4 cm when the Murphy tube was used (P < 0.01). Breath sounds disappeared when the ETT tip was further advanced up to 3.2+/-0.3 cm from the carina. We demonstrated that the eye of the Murphy tube reduces the reliability of chest auscultation in detecting endobronchial intubation. ⋯ The Murphy eye was designed to allow ventilation of the lung when the bevel of the endotracheal tube is occluded. We demonstrated that the eye of the Murphy tube reduces the reliability of chest auscultation in detecting endobronchial intubation.