Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2002
Morbid obesity and postoperative pulmonary atelectasis: an underestimated problem.
Perturbation of respiratory mechanics produced by general anesthesia and surgery is more pronounced in morbidly obese (MO) patients. Because general anesthesia induces pulmonary atelectasis in nonobese patients, we hypothesized that atelectasis formation would be particularly significant in MO patients. We investigated the importance and resorption of atelectasis after general anesthesia in MO and nonobese patients. Twenty MO patients were anesthetized for laparoscopic gastroplasty and 10 nonobese patients for laparoscopic cholecystectomy. We assessed pulmonary atelectasis by computed tomography at three different periods: before the induction of general anesthesia, immediately after tracheal extubation, and 24 h later. Already before the induction of anesthesia, MO patients had more atelectasis, expressed in the percentage of the total lung area, than nonobese patients (2.1% versus 1.0%, respectively; P < 0.01). After tracheal extubation, atelectasis had increased in both groups but remained significantly more so in the MO group (7.6% for MO patients versus 2.8% for the nonobese; P < 0.05). Twenty-four hours later, the amount of atelectasis remained unchanged in the MO patients, but we observed a complete resorption in nonobese patients (9.7% versus 1.9%, respectively; P < 0.01). General anesthesia in MO patients generated much more atelectasis than in nonobese patients. Moreover, atelectasis remained unchanged for at least 24 h in MO patients, whereas atelectasis disappeared in the nonobese. ⋯ We compared the resolution over time of pulmonary atelectasis after a laparoscopic procedure by performing computed tomography scans in two different groups of patients: 1 group had 10 nonobese patients, and in the other group there were 20 morbidly obese patients.
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Anesthesia and analgesia · Dec 2002
Comparative StudyA comparison of patient state index and bispectral index values during the perioperative period.
The patient state index (PSI), a quantitative electroencephalographic index, has been recently introduced into clinical practice as a monitor for assessing consciousness during sedation and general anesthesia. We designed this observational study to compare the sensitivity and specificity of the PSI with that of the bispectral index (BIS) with respect to their ability to predict the loss of consciousness and emergence from anesthesia, as well as to assess changes in IV (propofol) and inhaled (desflurane) anesthetics during the maintenance period. Twenty consenting patients scheduled for elective laparoscopic surgical procedures were enrolled in this prospective clinical study. Anesthesia was induced with propofol 2 mg/kg IV and fentanyl 1 micro g/kg IV, and tracheal intubation was facilitated with cisatracurium 0.3 mg/kg IV. Desflurane 4% in combination with nitrous oxide 60% in oxygen was administered for the maintenance of anesthesia. Comparative PSI and BIS values were obtained at specific time intervals during the induction, maintenance, and emergence periods. The changes in these indices were recorded after the administration of propofol (20 mg IV) or with 2% increases or decreases in the inspired concentration of desflurane during the maintenance period. With logistic regression models, both the BIS and PSI were found to be effective as predictors of unconsciousness (i.e., failed to respond to verbal stimuli) (P < 0.01). The PSI also correlated with the BIS during both the induction of (r = 0.78) and emergence from (r = 0.73) general anesthesia. However, the area under the receiver operating characteristic curve for detection of consciousness indicated a better performance with the PSI (0.95 +/- 0.04) than the BIS (0.79 +/- 0.04). During the maintenance period, the PSI values were comparable to the BIS in response to changes in propofol and desflurane but displayed greater interpatient variability. Finally, the PSI (versus BIS) values were less interfered with by the electrocautery unit during surgery (16% versus 65%, respectively). In conclusion, the PSI may prove to be a viable alternative to the BIS for evaluating consciousness during the induction of and emergence from general anesthesia, as well as for titrating the administration of propofol and desflurane during the maintenance period. However, further studies with the PSA device are needed to determine its role in anesthesia. ⋯ The patient state index could be a useful alternative to the bispectral index for assessing level of consciousness during the induction of and emergence from anesthesia, as well as for titrating IV and volatile anesthetics during surgery.
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Anesthesia and analgesia · Dec 2002
Residual paralysis induced by either vecuronium or rocuronium after reversal with pyridostigmine.
We investigated postoperative residual curarization after administration of either vecuronium or rocuronium with reversal by pyridostigmine in 602 consecutive patients without perioperative neuromuscular monitoring. On arrival in the recovery room, neuromuscular function was assessed both by acceleromyography in a train-of-four (TOF) pattern and also clinically by the ability to sustain a head-lift for >5 s and the tongue-depressor test. Postoperative residual curarization was defined as a TOF ratio <0.7. One fifth of 602 patients (vecuronium, 24.7%; rocuronium, 14.7%) had a TOF <0.7 in the recovery room. There were no significant differences in the TOF ratios between 10 mg and 20 mg of pyridostigmine. The patients with residual block had several associated factors: the absence of perioperative neuromuscular monitoring, the use of pyridostigmine, which is less potent than neostigmine, a larger dose of vecuronium, shorter time from the last neuromuscular blocker to TOF monitoring, or peripheral cooling. We conclude that significant residual neuromuscular block after vecuronium or rocuronium was not eliminated even with reversal by a large dose of pyridostigmine. ⋯ Without monitoring, the significant residual neuromuscular block after vecuronium or rocuronium is not eliminated even by reversal with a large dose of pyridostigmine and can still be a problem in the recovery room.
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Anesthesia and analgesia · Dec 2002
The effect of alterations in a preoperative assessment clinic on reducing the number and improving the yield of cardiology consultations.
Although preoperative assessment testing clinics (PATCs) can produce efficiency in the evaluation of surgical candidates, their effect on the use of consultants has not been studied. We hypothesized that changes in PATC procedures, education, and staffing could affect the use and yield of cardiology consultations. All PATC anesthesiologist-requested cardiology consultations for patients undergoing elective noncardiac surgery from 1993 to 1999 were reviewed. This period corresponded to 3 yr before and after a change in the PATC leadership, which resulted in more stringent consultation algorithms, a cardiac assessment and electrocardiogram interpretation educational program, and altered staffing of anesthesiologists and ancillary personnel. A single senior cardiologist completed all consultations. Data including age, sex, reason for consultation, resultant testing, consultant conclusions, cancellations, and surgical procedure and outcomes were collected. In the PRE and POST groups, respectively, 917 and 279 consultations (1.46% versus 0.49% [P = 0.0001] of noncardiovascular surgeries) were ordered despite an increase in the surgical case-mix acuity. In the POST group, significantly fewer consultations were ordered and significantly more required further testing to assess cardiac status. We conclude that changes in PATC consultation algorithms, education, and staffing can significantly decrease the use and yield of preoperative cardiology consultations. ⋯ Alterations in preoperative assessment testing clinic consultation algorithms, education, and staffing can significantly reduce the use of preoperative cardiology consultations while improving their overall yield.
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Anesthesia and analgesia · Dec 2002
The impact of a cardioprotective protocol on the incidence of cardiac complications after aortic abdominal surgery.
We analyzed a local database including 468 consecutive patients who underwent elective aortic abdominal surgery over an 8-yr period in a single institution. A new cardioprotective perioperative protocol was introduced in January 1997, and we questioned whether perioperative cardiac outcome could be favorably influenced by the application of a stepwise cardiovascular evaluation based on the American College of Cardiology/American Heart Association guidelines and by the use of antiadrenergic drugs. Clonidine was administered during surgery, and beta-blockers were titrated after surgery to achieve heart rates less than 80 bpm. We compared data of two consecutive 4-yr periods (1993-1996 [control period] versus 1997-2000 [intervention period]). Implementation of American College of Cardiology/American Heart Association guidelines was associated with increased preoperative myocardial scanning (44.3% vs 20.6%; P < 0.05) and coronary revascularization (7.7% vs 0.8%; P < 0.05). During the intervention period, there was a significant decrease in the incidence of cardiac complications (from 11.3% to 4.5%) and an increase in event-free survival at 1 yr after surgery (from 91.3% to 98.2%). Multivariate regression analysis showed that the combined administration of clonidine and beta-blockers was associated with a decreased risk of cardiovascular events (odds ratio, 0.3; 95% confidence interval, 0.1-0.8), whereas major bleeding, renal insufficiency, and chronic obstructive pulmonary disease were predictive of cardiac complications. In conclusion, cardiac testing was helpful to identify a small subset of high-risk patients who might benefit from coronary revascularization. Sequential and selective antiadrenergic treatments were associated with improved postoperative cardiac outcome. ⋯ Implementation of American College of Cardiology/American Heart Association guidelines and use of antiadrenergic drugs were associated with better cardiac outcomes after major vascular surgery.