Impact of deep hypothermic circulatory arrest on the BIS index.

STUDY OBJECTIVE: To investigate the influence of duration of deep hypothermic circulatory arrest (DHCA) on recovery of the bispectral index (BIS). DESIGN: Prospective cohort study. SETTING: Operating room of university teaching hospital. PATIENTS: 30 adult, ASA physical status III and IV patients scheduled for cardiac surgery with extracorporeal circulation (ECC) and DHCA. INTERVENTIONS: There were no study-specific interventions undertaken with the study patients. MEASUREMENTS: After induction of anesthesia, propofol and sufentanil were used for maintenance. Duration until BIS values reached indices of 10, 20, and 30 after DHCA was measured. DeltaBIS was defined as the difference between BIS before the start of ECC and after DHCA at the same nasopharyngeal body temperature. Data are means + or - SD (ranges). MAIN RESULTS: Duration of DHCA was 24 + or - 15 min (8-71 min). The deepest nasopharyngeal temperature was 20.1 + or - 2.7 degrees C at the end of DHCA. BIS reduction was 1.8/ degrees C. At the end of DHCA, BIS was 2 + or - 6 and at the end of ECC, BIS was 33 + or - 11. Duration until BIS reached a value of 10 (BIS10) was 23 + or - 21 min (0-83 min); until BIS reached 20 (BIS20): 36 + or - 36 min (0-140 min); and until BIS reached 30 (BIS30): 43 + or - 29 min (1-130 min). Regression analysis between duration of DHCA and BIS10 was R = 0.76; BIS20: R = 0.67; and BIS30: R = 0.54. CONCLUSION: Deep hypothermia influences BIS linearly. In addition, there appears to be a reasonable correlation between recovery of BIS values and duration of DHCA.

Thoracic but not lumbar epidural anaesthesia increases liver blood flow after major abdominal surgery.

BACKGROUND AND OBJECTIVE: Epidural blockade in major abdominal surgery bears the potential to increase gastrointestinal perfusion and thus to improve patient outcome. The aim of this study was to assess the differential influence of thoracic and lumbar epidural anaesthesia and analgesia (EAA) on blood lactate levels and central venous oxygen saturation (ScvO2) as parameters of global oxygen supply/demand ratio, as well as on the plasma disappearance rate of indocyanine green (PDR(ICG)), a noninvasive method to evaluate liver perfusion. METHODS: We enrolled 17 patients receiving thoracic and 17 patients receiving lumbar EAA in addition to general anaesthesia for major abdominal surgery. Lactate, ScvO2 and PDR(ICG) were measured postoperatively on the ICU. Subsequently, epidural application of local anaesthetics was started with a bolus of bupivacaine 0.25% (thoracic 10 ml, lumbar 12 ml) followed by continuous infusion of bupivacaine (thoracic 8 ml h(-1) 0.175%, lumbar 10 ml h(-1) 0.125%) and fentanyl (2 microg ml(-1)). Central venous pressure was maintained by titrated volume replacement. Lactate, ScvO2 and PDR(ICG) were measured again after 2 h. RESULTS: In both the groups, the mean arterial pressure and heart rate as well as lactate levels and ScvO2 did not change significantly. Although there was a slight but not significant decrease of PDR(ICG) in patients with lumbar EAA (from 25.9 +/- 7.68 to 23.2 +/- 5.90; NS), thoracic EAA resulted in a significant increase of PDR(ICG) (from 21.3 +/- 5.13 to 24.0 +/- 6.66; P < 0.05) for the group mean, but with substantial variability in individual patients in the lumbar EAA group. CONCLUSION: Liver perfusion was increased with thoracic but not lumbar EAA after major abdominal surgery in most patients. PDR(ICG) allows assessment of individual changes of liver blood flow due to therapeutic intervention, for example, EAA.

Airway injuries after one-lung ventilation: a comparison between double-lumen tube and endobronchial blocker: a randomized, prospective, controlled trial.

BACKGROUND: Vocal cord injuries, postoperative hoarseness, and sore throat are common complications after general anesthesia. One-lung ventilation can be achieved via two techniques: double-lumen endotracheal tube or endobronchial blocker such as the Arndt blocker. The current study was designed to assess the impact of these techniques for one-lung ventilation on the incidence and severity of postoperative hoarseness, vocal cord lesions, and sore throat. METHODS: In this prospective trial, 60 patients were randomly assigned to two groups. One-lung ventilation was achieved with either an endobronchial blocker (blocker group) or a double-lumen-tube (double-lumen group). Postoperative hoarseness and sore throat were assessed at 24, 48, and 72 h after surgery. Bronchial injuries and vocal cord lesions were examined by bronchoscopy immediately after surgery. RESULTS: In 56 included patients, postoperative hoarseness occurred significantly more frequently in the double-lumen group compared with the blocker group: 44% versus 17%, respectively (P = 0.046). Similar findings were observed for vocal cord lesions: 44% versus 17%, respectively (P = 0.046). The incidence of bronchial injuries was comparable between groups (P = 0.540). Cumulative number of days with hoarseness and sore throat were significantly increased in the double-lumen group compared with the blocker group (P < 0.01). No major complications such as bronchial ruptures were observed. CONCLUSIONS: Clinicians should be aware of an increased incidence of minor airway injuries that may impair patient satisfaction when using a double-lumen tube instead of an endobronchial blocker for one-lung ventilation.

A-line, bispectral index, and estimated effect-site concentrations: a prediction of clinical end-points of anesthesia.

Autoregressive modeling with exogenous input of middle-latency auditory evoked potentials (A-Line AEP index, AAI) has been developed for monitoring depth of anesthesia. We investigated the prediction of recovery and dose-response relationship of desflurane and AAI or bispectral index (BIS) values. Twenty adult men scheduled for radical prostatectomy were recruited. To minimize opioid effects, analgesia was provided by a concurrent epidural in addition to the general anesthetic. Electrodes for AAI and BIS monitoring and a headphone for auditory stimuli were applied. Propofol and remifentanil were used for anesthetic induction. Maintenance of anesthesia was with desflurane only. For comparison to AAI and BIS monitor parameters, pharmacokinetic models for desflurane and propofol distribution and effect-site concentrations were used to predict clinical end-points (Prediction probability P(K)). Patients opened their eyes at an AAI value of 47 +/- 20 and a BIS value of 77 +/- 14 (mean +/- sd), and the prediction probability for eye opening was P(K) = 0.81 for AAI, P(K) = 0.89 for BIS, and P(K) = 0.91 for desflurane effect-site concentration. The opening of eyes was best predicted by the calculated desflurane effect-site concentration. The relationship between predicted desflurane effect-site concentration versus AAI and BIS was calculated by nonlinear regression analysis (r = 0.75 for AAI and r = 0.80 for BIS). The correlation between BIS and clinical end-points of anesthesia or the desflurane effect-compartment concentration is better than for the AAI.

Postoperative myalgia after succinylcholine: no evidence for an inflammatory origin.

UNLABELLED: A common side effect associated with succinylcholine is postoperative myalgia. The pathogenesis of this myalgia is still unclear; inflammation has been suggested but without convincing evidence. We designed the present study to investigate whether an inflammatory reaction contributes to this myalgia. The incidence and severity of succinylcholine-associated myalgia was determined in 64 patients pretreated with saline or dexamethasone before succinylcholine (n = 32 for each). Incidence and severity of myalgia did not differ significantly between the two groups: 15 patients in the dexamethasone group complained of myalgia compared with 18 patients in the saline group, and severe myalgia was reported by five patients and three patients, respectively (not significant). At 48 h after surgery, 12 patients in both groups still suffered from myalgia (not significant). In addition, interleukin-6 (IL-6) as an early marker of inflammation was assessed in a subgroup of 10 patients pretreated with saline. We found an increase of IL-6 for only three patients, but only one patient reported myalgia; no relationship between myalgia and the increase of IL-6 was found. In conclusion, there is no evidence for an inflammatory origin of succinylcholine-associated myalgia. IMPLICATIONS: Administration of dexamethasone before succinylcholine was not effective in decreasing the incidence or the severity of succinylcholine-induced postoperative myalgia. Furthermore, there was no significant relationship between postoperative myalgia and time course of interleukin-6 concentrations, a marker of inflammation. Pretreatment with dexamethasone is not justified to prevent postoperative myalgia after succinylcholine.