Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2002
Precardiopulmonary bypass right ventricular function is associated with poor outcome after coronary artery bypass grafting in patients with severe left ventricular systolic dysfunction.
Patients with severe left ventricular systolic dysfunction (LVSD) undergoing coronary artery bypass grafting (CABG) have an increased risk for morbidity and mortality. The purpose of this study was to assess the association of pre-CABG right ventricular (RV) function with outcome for patients with severe LVSD. We performed a retrospective evaluation of 41 patients with severe LVSD (left ventricular ejection fraction [LVEF] < or =25%) scheduled for nonemergent CABG. Data were obtained from review of medical records, transesophageal echocardiography tapes, and phone interview. The pre- and post-cardiopulmonary bypass (CPB) LVEF and the RV fractional area of contraction (RVFAC) were calculated by using intraoperative transesophageal echocardiography. Group 1 patients had an RVFAC < or =35% (n = 7), whereas Group 2 patients had RVFAC >35% (n = 34). The durations of mechanical ventilation and of intensive care unit and hospital stays are presented as the median. Pre-CABG LVEF was similar between Groups 1 and 2 (15.8% +/- 3.3% versus 17.8% +/- 3.9%). Compared with Group 2, Group 1 patients required greater duration of mechanical ventilation (12 days versus 1 day; P < 0.01), longer intensive care unit (14 versus 2 days; P < 0.01) and hospital (14 versus 7 days; P = 0.02) stays, had a more frequent incidence and severity of LV diastolic dysfunction, and had a smaller change in LVEF immediately after CPB (4.1% +/- 8.3% versus 12.5% +/- 9.2%; P = 0.03). All Group 1 patients died of cardiac causes within 2 yr of surgery; five died during the same hospital admission. Three Group 2 patients died: one of colon cancer at 18 mo after CABG and two of cardiac causes 24 and 48 mo after surgery. A fourth patient was awaiting cardiac transplantation 4 yr after surgery. The remaining Group 2 patients were New York Heart Association Classification I or II. For patients with severe LVSD undergoing CABG, pre-CPB RV dysfunction was associated with poor outcome. Patients with RVFAC >35% had a relatively uneventful perioperative course and good long-term survival, whereas patients with RVFAC < or =35% had a poor early and late outcome. Assessment of RV function is useful to further assess the risk of CABG. ⋯ Right ventricular function before cardiopulmonary bypass is associated with poor outcome after coronary artery surgery in patients with poor left ventricular function.
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Anesthesia and analgesia · Dec 2002
Initial experience with a novel heat-exchanging catheter in neurosurgical patients.
Even mild hypothermia provides marked protection against cerebral ischemia in animal models. Hypothermia may be of therapeutic value during neurosurgical procedures. However, current cooling systems often fail to induce sufficient hypothermia before the dura is opened. Furthermore, they usually fail to restore normothermia by the end of surgery, thus delaying extubation. We evaluated a new internal heat-exchanging catheter. Eight ASA physical status II-IV patients (29-72 yr) undergoing craniotomy were enrolled. After the induction of general anesthesia, we introduced the SetPoint catheter into the inferior vena cava via a femoral vein. The target core body temperature was 34 degrees C-34.5 degrees C. After reaching the target, core temperature was maintained until the dura was closed. Target core temperature was then set to 37.0 degrees C, and the patient was rewarmed as quickly as possible. Seven patients had a tumor resection, and one had an aneurysm clipped. The core-cooling rate was 3.9 degrees C +/- 1.6 degrees C/h, and the rewarming rate was 2.0 degrees C +/- 0.5 degrees C/h; core temperature was 35.9 degrees C +/- 0.2 degrees C by the end of surgery. Patients were subsequently kept normothermic for 3 h before the catheter was removed. No thrombus or other particulate material was identified on the extracted catheters. None of the patients suffered any complications that could be attributed to the SetPoint system or thermal management. ⋯ Because current systems for inducing therapeutic hypothermia are too slow, we tested an internal counter-current thermal management system during hypothermic neurosurgery. The SetPoint catheter cooled at 3.9 degrees C +/- 1.6 degrees C/h and rewarmed at 2.0 degrees C +/- 0.5 degrees C/h. Catheter-based internal thermal management thus seems to be rapid and effective.
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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.