Jay A. Anderson

Esmolol is more effective than sodium nitroprusside in reducing blood loss during orthognathic surgery

The goal of this study was to compare the efficacy of esmolol and sodium nitroprusside (SNP) as primary drugs for producing controlled hypotension and limiting blood loss during orthognathic surgery. Thirty ASA physical status I and II patients (mean age 22 yr) undergoing LeFort I maxillary osteotomies were randomly assigned to receive either esmolol (n = 15) or SNP (n = 15) as the primary drug to induce hypotension. All patients received a balanced anesthetic technique including isoflurane, with controlled hypotension during the down fracture of the maxilla. Patients assigned to the esmolol treatment group received boluses of 500 μg/kg of esmolol, followed by a continuous infusion of 100–300 μkg−1 ·min−1, and the SNP treatment group received a continuous infusion of SNP at 0.25--4.00 μkg−1· min−1; both infusions were nitrated to obtain a mean arterial blood pressure within the target range of 55--65 mm Hg. The mean arterial blood pressure during the hypotensive period was 58.7 ±0.7 (mean ± SEM) and 61.8 ± 0.4 mm Hg for esmolol and SNP, respectively (P < 0.001). In addition, 40% ± 4% of the observed values in the esmolol group and 53% ± 3% in the SNP group were outside the target range for mean arterial blood pressure (difference significant at P < 0.05), and a greater proportion of the deviations were above 65 mm Hg in the SNP group than in the esmolol group (0.64 vs 0.46, respectively, P < 0.05). The mean heart rate was 70 Rekha 3 beats/min (esmolol) and 100 ± 3 beats/min (SNP) (P < 0.001), and the mean blood loss was 436 ± 65 mL (esmolol) and 895 ± 101 mL (SNP) (P < 0.001). The surgical field was judged to be drier with esmolol than with SNP (P < 0.05). Plasma renin activity decreased slightly in the esmolol group, whereas in the SNP group it increased 267% (P < 0.001). The absence of the renin release may have facilitated the stability of controlled hypotension with esmolol. The advantages of esmolol over SNP for controlled hypotension during orthognathic surgery include greater control of blood pressure, reduction in blood loss, and a drier surgical field. These advantages must be weighed against the possibility of significant myocardial depression produced by intense β1-adrenergic blockade.

The effectiveness of flumazenil in reversing the sedation and amnesia produced by intravenous midazolam

In this double-blind study 31 outpatients undergoing third molar extraction were randomly assigned to one of two groups. All patients were sedated with intravenous midazolam (IV) by titration method. The flumazenil group (n = 20) received an average of 0.8 +/- 0.17 mg of flumazenil IV. The placebo patients (n = 11) each received 10 mL of normal saline. By both observer and patient alertness ratings, patients receiving flumazenil appeared significantly more alert than placebo patients at 5, 15, 30, and 60 minutes following reversal. After reversal the flumazenil group had significantly higher scores than the placebo group at all intervals through 60 minutes. All the patients receiving flumazenil were able to walk without assistance at 5 minutes, compared with only one patient in the placebo group, and more patients in the flumazenil group recognized the picture card shown to them at 5, 15, 30, and 60 minutes postreversal. Flumazenil is effective in terminating the amnestic properties of midazolam, but this appears to occur to a lesser extent than the reversal of its sedative properties.

Use of capnography and transcutaneous oxygen monitoring during outpatient general anesthesia for oral surgery

The combination of the capnograph (respired CO2 monitor) and the transcutaneous oxygen monitor was evaluated as a non-invasive system for monitoring of respiratory function in 10 ASA class I patients undergoing ultralight general anesthesia for removal of third molars. Capnography proved to be a sensitive and accurate method for detecting apnea and airway obstruction using the continuous display of the CO2 waveform. All episodes of apnea or obstruction were immediately detected as the respired CO2 level fell to zero baseline. The end-tidal CO2 (PetCO2) obtained via nasal prong sampling was not significantly different from the PaCO2. PetCO2 values served as useful indicators of hypoventilation. During steady-state conditions of respiration, transcutaneous oxygen tensions (PtcO2) correlated well with simultaneously measured PaO2 (r = 0.93). However, during any period when oxygenation was rapidly changing (step increase in FIO2, step decrease in FIO2, or apnea) the PtcO2 lagged behind changes in PaO2 even after a five-minute equilibration period, thereby not accurately reflecting the true state of oxygenation. Consequently, the transcutaneous oxygen monitor does not appear to be optimal as a respiratory monitor in the setting of ultralight general anesthesia where rapid, critical changes in oxygenation must be detected without delay.

Benzocaine-induced methemoglobinemia during general anesthesia

A case is reported in which a patient developed cyanosis under general anesthesia due to methemoglobinemia. The cause of the methemoglobinemia was benzocaine applied topically to the pharynx and trachea. When confronted with cyanosis in the absence of cardiac or pulmonary disease, one must seriously consider the diagnosis of methemoglobinemia. Supplemental oxygen should be administered and methylene blue given intravenously. If possible, determination of arterial blood gases should be made to obtain the methemoglobin concentration. Finally, all medical and dental personnel using benzocaine should be aware of the recommended dose and the possible complications of overdosage.

Subcutaneous emphysema producing airway compromise after anesthesia for reduction of a mandibular fracture: A case report and review of the literature

Subcutaneous emphysema can occur as the result of trauma, surgery, and anesthesia. A case is presented of extensive subcutaneous emphysema after anesthesia for oral surgical reduction of a mandibular fracture. A discussion of the diagnosis, pathophysiology, and treatment of subcutaneous emphysema follows.

Multimodal Protocol Reduces Postoperative Nausea and Vomiting in Patients Undergoing Le Fort I Osteotomy

PURPOSE To assess the impact of a multimodal antiemetic protocol on postoperative nausea and vomiting (PONV) after Le Fort I osteotomy. MATERIALS AND METHODS Consecutive patients undergoing Le Fort I osteotomy with or without additional procedures at a single academic institution were recruited as the intervention cohort for an institutional review board-approved prospective clinical trial with a retrospective comparison group. The intervention cohort was managed with a multimodal antiemetic protocol, including total intravenous anesthesia; prophylactic ondansetron, steroids, scopolamine, and droperidol; gastric decompression at surgery end; opioid-sparing analgesia; avoidance of morphine and codeine; prokinetic erythromycin; and fluids at a minimum of 25 mL/kg. The comparison group consisted of consecutive patients from a larger study who underwent similar surgical procedures before protocol implementation. Data, including occurrence of PONV, were extracted from medical records. Data were analyzed in bivariate fashion with the Fisher exact and Wilcoxon rank-sum tests. Logistic regression was used to compare the likelihood of nausea and vomiting in the 2 cohorts after controlling for demographic and surgical characteristics. A P value less than .05 was considered significant. RESULTS The intervention (n = 93) and comparison (n = 137) groups were similar in gender (58% and 65% female patients; P = .29), race (72% and 71% Caucasian; P = .85), age (median, 19 and 20 years old; P = .75), proportion of patients with known risk factors for PONV (P = .34), percentage undergoing bimaxillary surgery (60% for the 2 groups), and percentage for whom surgery time was longer than 180 minutes (63% and 59%; P = .51). Prevalence of postoperative nausea was significantly lower in the intervention group than in the comparison group (24% vs 70%; P < .0001). Prevalence of postoperative vomiting was likewise significantly lower in the intervention group (11% vs 28%; P = .0013). The likelihood that patients in the comparison group would develop nausea was 8.9 and that for vomiting was 3.7 times higher than in the intervention group. CONCLUSION This multimodal protocol was associated with substantially decreased prevalence of PONV in patients undergoing Le Fort I osteotomy.

A double-blind comparison of low-dose intravenous ketamine and methohexital in adults

Two ultralight general anesthetic techniques, one using low-dose ketamine and the other using methohexital as the primary anesthetic agent, were compared for efficacy, safety, and psychomotor recovery in a double-blind fashion for use during third molar surgery. Low-dose intravenous ketamine as the primary anesthetic following premedication with fentanyl and midazolam, and in conjunction with nitrous oxide, appeared to produce less hypoxia, hypercarbia, and apnea than when methohexital was used. No significant differences were noted in heart rate or blood pressure between the techniques. The ketamine technique was universally preferred by the surgeons and anesthesiologists because of superior patient cooperation and airway management. No unpleasant psychomimetic side effects of significance were noted with the use of ketamine. Postoperative recovery took slightly longer in the ketamine group, with patients being judged fit for discharge approximately 10 to 15 minutes later than the patients who received methohexital.

Postdischarge Nausea and Vomiting Remains Frequent After Le Fort I Osteotomy Despite Implementation of a Multimodal Antiemetic Protocol Effective in Reducing Postoperative Nausea and Vomiting

PURPOSE To assess the prevalence of postdischarge nausea and vomiting (PDNV) after Le Fort I osteotomy with and without the use of a multimodal antiemetic protocol shown to decrease postoperative nausea and vomiting (PONV). MATERIALS AND METHODS Consecutive patients undergoing Le Fort I osteotomy with or without additional procedures at a single academic institution formed the intervention cohort for an institutional review board-approved prospective clinical trial with a retrospective comparison group. The intervention cohort was managed with a multimodal antiemetic protocol. The comparison group consisted of consecutive patients who underwent similar surgical procedures at the same institution before protocol implementation. All patients were asked to complete a postdischarge diary documenting the occurrence of nausea and vomiting. Those who completed the diaries were included in this analysis. Data were analyzed with the Fisher exact test and the Wilcoxon rank sum test. A P value less than .05 was considered significant. RESULTS Diaries were completed by 85% of patients in the intervention group (79 of 93) and 75% of patients in the comparison group (103 of 137). Patients in the intervention (n = 79) and comparison (n = 103) groups were similar in the proportion of patients with validated risk factors for PDNV, including female gender, history of PONV, age younger than 50 years, opioid use in the postanesthesia care unit (PACU), and nausea in the PACU (P = .37). The prevalence of PDNV was unaffected by the antiemetic protocol. After discharge, nausea was reported by 72% of patients in the intervention group and 60% of patients in the comparison group (P = .13) and vomiting was reported by 22% of patients in the intervention group and 29% of patients in the comparison group (P = .40). CONCLUSION Modalities that successfully address PONV after Le Fort I osteotomy might fail to affect PDNV, which is prevalent in this population. Future investigation will focus on methods to minimize PDNV.