Changes in stroke volume during an alveolar recruitment maneuvers through a stepwise increase in positive end expiratory pressure and transient continuous positive airway pressure in anesthetized patients. A prospective observational pilot study.

BACKGROUND AND AIMS: Recruitment maneuvers may be used during anesthesia as part of perioperative protective ventilation strategy. However, the hemodynamic effect of recruitment maneuvers remain poorly documented in this setting. MATERIAL AND METHODS: This was a prospective observational study performed in operating theatre including patients scheduled for major vascular surgery. Patients were monitored with invasive arterial pressure and esophageal doppler. After induction of general anesthesia, before surgery began, preload optimization based on stroke volume (SV) variation following fluid challenge was performed. Then, an alveolar recruitment maneuver (ARM) through stepwise increase in positive end expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) was performed. Hemodynamic data were noted before, during, and after the alveolar recruitment maneuver. RESULTS: ARM through stepwise increase in PEEP and CPAP were applied in 22 and 14 preload independent patients, respectively. Relative changes in SV during ARMs were significantly greater in the ARMCPAP group (-39 ± 20%) as compared to the ARMPEEP group (-15 ± 22%; P = 0.002). The difference (95% CI) in relative decrease in SV between ARMCPAP and ARMPEEP groups was -24% (-38 to -9; P = 0.001). Changes in arterial pressure, cardiac index, pulse pressure variation, peak velocity, and corrected flow time measures were not different between groups. CONCLUSION: During anesthesia, in preload independent patients, ARMs through CPAP resulted in a significantly greater decrease in SV than stepwise increase in PEEP. During anesthesia, ARM should be used cautiously.

Comparison of the Mallampati Classification in Sitting and Supine Position to Predict Difficult Tracheal Intubation: A Prospective Observational Cohort Study.

BACKGROUND: The Mallampati classification (MLPT) is normally evaluated in the sitting position. However, many patients cannot be evaluated in the sitting position for medical reasons. Thus, we compared the MLPT in sitting and supine positions in predicting difficult tracheal intubation (DTI). We hypothesized that the diagnostic accuracy of the MLPT performed in sitting and supine positions would differ. METHODS: We performed a single-center prospective observational study in adult patients who received general anesthesia and orotracheal intubation for noncardiac surgery. During the preanesthesia consultation, the MLPT in the sitting position was recorded. The day of surgery, the MLPT in the supine position and the difficulty of intubation (DTI) were recorded by an independent observer. The diagnostic performance of the MLPT for the prediction of DTI was evaluated in the sitting and supine positions through the area under the receiver operating characteristic (ROC) curve. The performance of the Naguib score in predicting DTI was calculated with the MLPT in sitting and supine positions. RESULTS: Among the 3036 patients, 157 (5.1%) had DTI. The area under the ROC curve for the MLPT in supine position (0.82 [0.78-0.84]) was greater than that for the MLPT in the sitting position (0.70 [0.66-0.75]; P < .001). The relationship between the sitting and supine MLPTs was moderate (Spearman rank correlation coefficient: 0.50; P < .001). The area under ROC curve for predicting DTI by the Naguib score calculated with the supine MLPT (0.78 [95% confidence interval, 0.74-0.82]) was greater than that for the Naguib score calculated with MLPT in the sitting position (0.69 [95% confidence interval, 0.63-0.74)]; P < .001). CONCLUSIONS: The MLPT performed in the supine position is possibly superior to that performed in the sitting position for predicting difficult intubation in adults.