ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundPreoxygenation with tidal volume breathing for 3–5 min is recommended by Hamilton and Eastwood. This report compares tidal volume preoxygenation technique with deep breathing techniques for 30–60 s.MethodsThe study was conducted in two parts on patients undergoing elective coronary bypass grafting. In the first group (n = 32), each patient underwent all of the following preoxygenation techniques: the traditional technique consisting of 3 min of tidal volume breathing at an oxygen flow of 5 l/min; four deep breaths within 30 s at oxygen flows of 5 l/min, 10 l/min, and 20 l/min; and eight deep breaths within 60 s at an oxygen flow of 10 l/min. The mean arterial oxygen tensions after each technique were measured and compared. In the second group (n = 24), patients underwent one of the following techniques of preoxygenation: the traditional technique (n = 8), four deep breaths (n = 8), and eight deep breaths (n = 8). Apnea was then induced, and the mean times of hemoglobin desaturation from 100 to 99, 98, 97, 96, and 95% were determined.ResultsIn the first group of patients, the mean arterial oxygen tension following the tidal breathing technique was 392 ± 72 mmHg. This was significantly higher (P< 0.05) than the values obtained following the four deep breath technique at oxygen flows of 5 l/min (256 ± 73 mmHg), 10 l/min (286 ± 69 mmHg), and 20 l/min (316 ± 67 mmHg). In contrast, the technique of eight deep breaths resulted in a mean arterial oxygen tension of 369 ± 69 mmHg, which was not significantly different from the value achieved by the traditional technique. In the second group of patients, apnea following different techniques of preoxygenation was associated with a slower hemoglobin desaturation in the eight‐deep‐breaths technique as compared with both the traditional and the four‐deep‐breaths techniques.ConclusionRapid preoxygenation with the eight deep breaths within 60 s can be used as an alternative to the traditional 3‐min technique.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundWhen capsaicin is injected intradermally, hyperalgesia develops around the injection site. The authors observed that volunteers report painful sensations in the skin remote from the injection site during tourniquet constriction of the affected extremity.MethodsEach volunteer received an intradermal injection of capsaicin on the volar forearm, followed by intermittent tourniquet constriction of the extremity. In some participants, the tourniquet position was rotated between different sites on the upper extremities. Laser Doppler measurements were made in the skin to measure capillary blood flow during pain magnification.ResultsHyperalgesia developed in the volunteers who were tested after the capsaicin injection. Blood flow increased three times in the dermal capillaries remote from the injection site after capsaicin injection. The tourniquet‐induced pain reached peak intensity soon after tourniquet inflation. Tourniquet constriction of the arm on the affected side reliably induced painful exacerbation in each person tested. The quality of the sensation was described as burning and extended across the arm in most volunteers. Only when pinprick hyperalgesia was detectable did the volunteers experience the diffuse, immediate pain sensation. The pain initiated by the tourniquet constriction likely is related to changes in skin capillary blood flow.ConclusionsLow cutaneous blood perfusion is related to the intensity of ongoing, spontaneous pain when secondary hyperalgesia is present. The specific trigger(s) have yet to be identified.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundNitrous oxide limits intraoperative hypothermia because the vasoconstriction threshold with nitrous oxide is higher than with equi–minimum alveolar concentrations of sevoflurane or isoflurane, presumably because of its stimulating actions on the sympathetic nervous system. Xenon, in contrast, does not cause sympathetic activation. Therefore, the authors tested the hypothesis that the vasoconstriction threshold during xenon–isoflurane anesthesia is less than during nitrous oxide–isoflurane anesthesia or isoflurane alone.MethodsFifteen patients each were randomly assigned to one of three 1‐minimum alveolar concentration anesthetic regimens: (1) xenon, 43% (0.6 minimum alveolar concentration) and isoflurane, 0.5% (0.4 minimum alveolar concentration); (2) nitrous oxide, 63% (0.6 minimum alveolar concentration) and isoflurane 0.5%; or (3) isoflurane, 1.2%. Ambient temperature was maintained near 23°C and the patients were not actively warmed. Thermoregulatory vasoconstriction was evaluated using forearm‐minus‐fingertip skin temperature gradients. A gradient exceeding 0°C indicated significant vasoconstriction. The core‐temperature threshold that would have been observed if skin had been maintained at 33°C was calculated from mean skin and distal esophageal temperatures at the time of vasoconstriction.ResultsThe patients’ demographic variables, preinduction core temperatures, ambient operating room temperatures, and fluid balance were comparable among the three groups. Heart rates were significantly less during xenon anesthesia than with nitrous oxide. The calculated vasoconstriction threshold was lowest with xenon (34.6 ± 0.8°C, mean ± SD), intermediate with isoflurane alone (35.1 ± 0.6°C), and highest with nitrous oxide (35.7 ± 0.6°C). Each of the thresholds differed significantly.ConclusionsXenon inhibits thermoregulatory control more than isoflurane, whereas nitrous oxide is the least effective in this respect.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundThis multicenter, assessor‐blinded, randomized study was done to confirm and extend a pilot study showing that intramuscular rocuronium can provide adequate tracheal intubating conditions in infants (2.5 min) and children (3 min) during halothane anesthesia.MethodsThirty‐eight infants (age range, 3–12 months) and 38 children (age range, 1 to 5 yr) classified as American Society of Anesthesiologists physical status 1 and 2 were evaluated at four investigational sites. Anesthesia was maintained with halothane and oxygen (1% end‐tidal concentration if < 2.5 yr; 0.80% end‐tidal concentration if > 2.5 yr) for 5 min. One half of the patients received 0.45 mg/kg intravenous rocuronium. The others received 1 mg/kg (infants) or 1.8 mg/kg (children) of intramuscular rocuronium into the deltoid muscle. Intubating conditions and mechanomyographic responses to ulnar nerve stimulation were assessed.ResultsThe conditions for tracheal intubation at 2.5 and 3 min in infants and children, respectively, were inadequate in a high percentage of patients in the intramuscular group. Nine of 16 infants and 10 of 17 children had adequate or better intubating conditions at 3.5 and 4 min, respectively, after intramuscular rocuronium. Better‐than‐adequate intubating conditions were achieved in 14 of 15 infants and 16 of 17 children given intravenous rocuronium. Intramuscular rocuronium provided ≥ 98% blockade in 7.4 ± 3.4 min (in infants) and 8 ± 6.3 min (in children). Twenty‐five percent recovery occurred in 79 ± 26 min (in infants) and in 86 ± 22 min (in children).ConclusionsIntramuscular rocuronium, in the doses and conditions tested, does not consistently provide satisfactory tracheal intubating conditions in infants and children and is not an adequate alternative to intramuscular succinylcholine when rapid intubation is necessary.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundChronic nociceptive input induces sensitization and changes in regulatory reflexes in animal models. In humans, postoperative somatic and visceral sensitization and the secondary effects on reflex gut motility are unclear.MethodsSomatic and visceral sensation and gastrointestinal motility were evaluated after abdominal hysterectomies in 50 patients who were randomized to receive double‐blinded postoperative 48‐h infusions of morphine or tramadol. Pain scores, rectal distension, skin electric sensation and pain tolerance thresholds, and gastrointestinal transit were assessed before and after operation, during and after analgesic infusions.ResultsPain intensity scores decreased similarly with morphine and tramadol infusions (total doses, 66.8 ± 20 mg and 732.4 ± 152 mg [mean ± SD], respectively). Skin pain tolerance thresholds in the incisional dermatome remained similar with morphine and tramadol throughout the study. During morphine infusions, pain tolerance thresholds on the shoulder increased (P< 0.05) and then decreased after discontinuation on day 4 (P< 0.02) compared with before operation. Rectal distension pain tolerance pressure thresholds increased after operation during morphine infusions (P< 0.05). Similar but nonsignificant trends occurred with tramadol. Orocecal and colonic transit times increased after operation with both morphine and tramadol (P< 0.005), but gastric emptying was prolonged only with morphine (P= 0.03). All motility and sensory parameters had returned to preoperative levels by 1 month after operation.ConclusionsPain control was equally effective with morphine and tramadol infusions. No somatic or visceral sensitization was evident during morphine and tramadol infusions, but pain tolerance thresholds as markers of antinociception were increased more during morphine infusions. The significant sensitization seen only after morphine discontinuation may be due to convergent visceral input. Gut motility was prolonged significantly by visceral surgery itself and also by morphine.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

BackgroundThe authors compared the performance of a prototype intubation aid that incorporated plastic illumination and image guides into a stylet with fiberoptic bronchoscopy and direct laryngoscopy for tracheal intubation by novice users.MethodsIn a randomized, nonblinded design, patients were assigned to direct laryngoscopy, fiberoptic bronchoscopy, or imaging stylet intubation groups. The quality of laryngeal view and ease with which it was attained for each intubation was graded by the laryngoscopist. Time to intubation was measured in 1‐min increments. A sore‐throat severity grade was obtained after operation.ResultsThere were no differences in demographic, physical examination, or surgical course characteristics among the groups. The laryngoscope produced an adequate laryngeal view more easily than did the imaging stylet or bronchoscope (P= 0.001) but caused the highest incidence of postoperative sore throat (P< 0.05). Although the time to intubation for direct laryngoscopy was shorter than for imaging stylet, which was shorter than fiberoptic bronchoscopy (P< 0.05), the quality of laryngeal view with the imaging stylet was inferior to both direct laryngoscopy and fiberoptic bronchoscopy techniques (P< 0.05).ConclusionsNovices using the imaging stylet produce fewer cases of sore throat (compared with direct laryngoscopy) and can intubate faster than when using a bronchoscope in anesthetized adult patients. The imaging stylet may be a useful aid for tracheal intubation, especially for those unable to maintain skills with a bronchoscope.

ISSN:0003-3022    

出版商:OVID    

年代:1999

数据来源: OVID