Perioperative incidence of airway obstructive and hypoxemic events in patients with confirmed or suspected sleep apnea - a prospective, randomized pilot study comparing propofol/remifentanil and sevoflurane/remifentanil anesthesia.

BACKGROUND: Obstructive sleep apnea (OSA) is a risk factor for perioperative complications but data on anesthesia regimen are scarce. METHODS: In patients with established or strongly suspected OSA, we assessed in a prospective, randomized design the effects on nocturnal apnea-hypopnea-index (AHI) and oxygen saturation (SpO2) of propofol/remifentanil or sevoflurane/remifentanil based anesthesia. Patients were selected by a history for OSA and / or a positive STOP - questionnaire and received general anesthesia using remifentanil (12 µg/kg/h) combined either with propofol (4-6 mg/kg/h, n = 27) or sevoflurane (approx. 2.2 vol% endtidal, n = 27). AHI and SpO2 were measured during the nights before and after anesthesia. RESULTS: There were no differences in AHI between anesthetic regimens nor between the pre- and postoperative nights (propofol: 8.6 h- 1 (median, CI: 3.6-21.9) vs. 7.9 h- 1 (1.8-28.8); p = 0.97; sevoflurane: 3.8 h- 1 (1.8-7.3) vs. 2.9 h- 1 (1.2-9.5); p = 0.85). Postoperative minimum SpO2 (propofol: 80.7% ± 4.6, sevoflurane: 81.6 ± 4.6) did not differ from their respective preoperative baselines (propofol: 79.6% ± 6.5; p = 0.26, sevoflurane: 80.8% ± 5.2; p = 0.39). Even in patients with a preanesthetic AHI > 15, nocturnal AHI remained unchanged postoperatively. CONCLUSION: Thus, in a cohort of patients with suspected or confirmed OSA undergoing surgery of moderate duration and severity neither the volatile agent sevoflurane nor the intravenous anesthetic propofol altered nocturnal AHI or oxygen saturation, when combined with the short acting opioid remifentanil. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00005824 retrospectively registered on 03/12/2014.

Postoperative nausea and vomiting: The role of the dopamine D2 receptor TaqIA polymorphism.

BACKGROUND: The risk of developing postoperative nausea and vomiting (PONV), apart from conventional risk factors, probably includes a genetic background. OBJECTIVES: We examined the association of the DRD2 TaqIA polymorphism with PONV in a high-risk cohort of patients. DESIGN: A prospective, double-blind observational trial. SETTING: Single-centre primary care in Western Germany. PATIENTS: A total of 306 patients undergoing elective strabismus surgery under anaesthesia with etomidate/alfentanil/mivacurium (induction) and sevoflurane in air (maintenance). MAIN OUTCOME MEASURES: Nausea as well as retching/vomiting was recorded for 24 h postoperatively. The DRD2 TaqIA polymorphism (rs1800497) was genotyped using a Taqman assay and the relationship between DRD2 TaqIA polymorphism and PONV was examined by univariate and multivariate analysis. RESULTS: Regarding known risk factors for developing PONV, no patient with the A1A1 genotype (n = 15) had a history of PONV, while A1A2 carriers (n = 115) and A2A2 carriers (n = 176) had a history of PONV in 22.6 and 10.8% of patients, respectively (P = 0.005). Overall, the incidence of nausea was 40.1% and the incidence of vomiting/retching was 32.7%. Univariate analysis showed that postoperative nausea was not associated with TaqIA genotypes, but the incidence of retching/vomiting in A1A2 and A2A2 genotypes was more than 34% compared with zero in A1A1 genotypes (P = 0.022). Age, sex, smoking status and a history of PONV were independent predictors for nausea as well as for retching/vomiting, as expected, while DRD2 TaqIA polymorphism showed no independent significant impact. CONCLUSION: In a white cohort, the TaqIA A2 allele is significantly associated with a history of PONV, which may explain the increased incidence of PONV but has no further independent influence. TRIAL REGISTRATION: German registry of clinical trials identifier: DRKS00005681.

Bilateral Blindness due to Ischemic Optic Nerve Neuropathy After Abdominal Surgery.

Postoperative blindness is an unpredictable, devastating, and yet not-uncommon complication of anesthesia. We present the case of a patient who suffered bilateral loss of eyesight after surgery. The diagnostic evidence led us to believe that it was bilateral posterior ischemic optic neuropathy; however, the true mechanisms of damage remain a matter of speculation.

Visual loss following intraocular gas injection.

INTRODUCTION: The range of indications for vitreoretinal surgery has widened in recent years, and intraocular gas application is frequently performed as part of retinal surgery, with the aim of achieving long-acting tamponade. METHODS: Selective literature review. RESULTS: An intraocular gas bubble containing perfluoropropane (C(3)F(8)) or sulfur hexafluoride (SF(6)) can expand during anesthesia due to nitrous oxide diffusion and cause retinal ischemia and postoperative blindness. A decrease in atmospheric pressure associated with travel to high altitude can have the same effect. Case reports suggest that, considering physical properties of these gases and ocular physiology, patients remain at risk for at least three months after intraocular gas application. DISCUSSION: Both doctors and patients need to be well informed about the hazards of intraocular gas application as good communication may prevent complications. If in doubt, the anesthesiologist should avoid nitrous oxide, in particular in the unconscious patient.

Corticosteroids and inhaled salbutamol in patients with reversible airway obstruction markedly decrease the incidence of bronchospasm after tracheal intubation.

BACKGROUND: In patients with bronchial hyperreactivity, airway instrumentation can evoke life-threatening bronchospasm. However, the best strategy for the prevention of bronchospasm has not been defined. Therefore, in a randomized, prospective, placebo-controlled study, the authors tested whether prophylaxis with either combined salbutamol-methylprednisolone or salbutamol alone (1) improves lung function and (2) prevents wheezing after intubation. METHODS: Thirty-one patients with partially reversible airway obstruction (airway resistance > 180%, forced expiratory volume in 1 s [FEV1] < 70% of predicted value, and FEV1 increase > 10% after two puffs of salbutamol), who were naive to anti-obstructive treatment, were randomized to receive daily for 5 days either 3 x 2 puffs (0.2 mg) of salbutamol alone (n = 16) or salbutamol combined with methylprednisolone (40 mg/day orally) (n = 15). Lung function was evaluated daily. Another 10 patients received two puffs of salbutamol 10 min before anesthesia. In all patients, wheezing was assessed before and 5 min after tracheal intubation. RESULTS: Within 1 day, both salbutamol and salbutamol-methylprednisolone treatment significantly improved airway resistance (salbutamol, 4.3+/- 2.0 [SD] to 2.9+/-1.3 mmHg x s x l(-1); salbutamol-methylprednisolone, 5.5+/-2.9 to 3.4+/-1.7 mmHg x s x l(-1)) and FEV1 (salbutamol, 1.79+/-0.49 to 2.12+/-0.61 l; salbutamol-methylprednisolone, 1.58+/-0.66 to 2.04+/-1.05 l) to a steady state, with no difference between groups. However, regardless of whether single-dose salbutamol preinduction or prolonged salbutamol treatment was used, most patients (8 of 10 and 7 of 9) experienced wheezing after intubation. In contrast, only one patient receiving additional methylprednisolone experienced wheezing (P = 0.0058). CONCLUSIONS: : Pretreatment with either salbutamol alone or salbutamol combined with methylprednisolone significantly and similarly improves lung function within 1 day. However, only combined salbutamol-methylprednisolone pretreatment decreases the incidence of wheezing after tracheal intubation. Therefore, in patients with bronchial hyperreactivity, preoperative treatment with combined corticosteroids and salbutamol minimizes intubation-evoked bronchoconstriction much more effectively than the inhaled beta2-sympathomimetic salbutamol alone.