The prediction of difficult intubation in obese patients using mirror indirect laryngoscopy: A prospective pilot study.

BACKGROUND: The incidence of difficult laryngoscopy and intubation in obese patients is higher than in the general population. Classical predictors of difficult laryngoscopy and intubation have been shown to be unreliable. We prospectively evaluated indirect mirror laryngoscopy as a predictor of difficult laryngoscopy in obese patients. MATERIALS AND METHODS: 60 patients with a body mass index (BMI) greater than 30, scheduled to undergo general anesthesia, were enrolled. Indirect mirror laryngoscopy was performed and was graded 1-4 according to Cormack and Lehane. A view of grade 3-4 was classified as predicting difficult laryngoscopy. Additional assessments for comparison were the Samsoon and Young modification of the Mallampati airway classification, Wilson Risk Sum Score, neck circumference, and BMI. The view obtained upon direct laryngoscopy after induction of general anesthesia was classified according to Cormack and Lehane as grade 1-4. RESULTS: Sixty patients met the inclusion criteria; however, 8 (13.3%) patients had an excessive gag reflex, and examination of the larynx was not possible. 15.4% of patients who underwent direct laryngoscopy had a Cormack and Lehane grade 3 or 4 view and were classified as difficult. Mirror laryngoscopy had a tendency toward statistical significance in predicting difficult laryngoscopy in these patients. CONCLUSIONS: This study is consistent with previous studies, which have demonstrated that no one individual traditional test has proven to be adequate in predicting difficult airways in the obese population. However, the new application of an old test - indirect mirror laryngoscopy - could be a useful additional test to predict difficult laryngoscopy in obese patients.

Transesophageal echocardiographic and oxymetric evidence of intraoperative reversal of flow through a patent foramen ovale during an off-pump coronary artery bypass grafting.

Mechanical stabilization of target coronary arteries in the beating heart has facilitated the practice of "off-pump" coronary artery bypass grafting. Exposing the target coronary artery for stabilization involves maneuvers that frequently cause hemodynamic alterations including decreased cardiac output and increased pulmonary artery and/or central venous pressures (CVP). The presence of a patent foramen ovale (PFO) in the setting of increased CVP may produce a right-to-left shunt through the PFO. We report a case of a patient undergoing off-pump coronary artery bypass grafting with a PFO with a left to right atrium shunt flow of 307 mL/min. During manipulation and elevation of the heart to expose the target vessel, the CVP increased from 15 to 30 mm Hg and the shunt through the PFO reversed direction, going from right to left atrium with a flow of 161 mL/min. Mixed venous oxygen saturation and the calculated shunt fraction decreased from 84% to 78% and 14% to 10%, respectively. All parameters returned to normal after the heart was lowered back inside the chest.