Impact of Increased End-Tidal Carbon Dioxide on Continuous Noninvasive Hemoglobin Monitoring during Laparoscopic Gastrectomy: A Randomized Controlled Study.

The pulse CO-Oximetry allows continuous, noninvasive monitoring of hemoglobin (SpHb). We assessed the impact of increased end-tidal carbon dioxide (EtCO2) on the accuracy and trending ability of SpHb in laparoscopic surgery. Participants (n = 64) were randomly allocated to the low carbon dioxide (CO2) group (EtCO2: 30-35 mmHg) or the high CO2 group (EtCO2: 40-45 mmHg). The SpHb and laboratory hemoglobin (tHb) were obtained during surgery. The correlation coefficient (r) between SpHb and tHb showed greater tendency in the low CO2 group (r = 0.68) than in the high CO2 group (r = 0.43). The bias (precision) was -1.18 (1.09) with a limit of agreement (LOA) of -3.31 to 0.95 in low CO2 group and -1.02 (1.24) with a LOA of -3.45 to 1.42 in high CO2 group; they did not differ significantly between the groups (p = 0.246). The low CO2 group showed a high concordance rate of 95.9% and a moderate correlation between ΔSpHb and ΔtHb (r = 0.53). However, the high CO2 group showed a concordance rate of 77.8% and no correlation between ΔSpHb and ΔtHb (r = 0.11). In conclusion, increased EtCO2 significantly reduced the trending ability of SpHb during laparoscopic surgery. Caution should be executed when interpreting SpHb values during laparoscopic surgery in patients with hypercapnia.

Left paratracheal pressure versus cricoid pressure for successful laryngeal mask airway insertion in adult patients: a randomized, non-inferiority trial.

BACKGROUND: Cricoid pressure (CP) is used to prevent pulmonary aspiration of regurgitated gastric contents and gastric insufflation during positive-pressure ventilation. However, CP impedes the successful insertion of laryngeal mask airway (LMA). Left paratracheal pressure (LPP), a maneuver of applying backward digital force at the lower left paratracheal level, was recently introduced as an alternative to CP. We assessed whether LPP is non-inferior to CP in successful LMA insertion on the first attempt in adult patients undergoing general anesthesia. METHODS: In this non-inferiority randomized controlled trial, 108 patients undergoing general anesthesia were randomly allocated to receive either LPP or CP during LMA insertion. The primary outcome was the success rate of LMA insertion on the first attempt. The margin of non-inferiority was defined as 15%. RESULTS: The success rate of LMA insertion on the first attempt was 68.5% (37/54) in the LPP group and 51.9% (28/54) in the CP group (P=0.077) with between-group difference of 16.7% (two-sided 95% CI, -1.9% to 35.2%). Time for successful device insertion was comparable in the two groups (P=0.355), whereas LMA insertion was easier in the LPP group than in the CP group (P=0.001). There was no significant difference between the two groups for change in antral cross-sectional area measured before and after mask ventilation (P=0.081). No serious complication was evident in any group. CONCLUSIONS: This randomized clinical trial demonstrated the non-inferiority of LPP over CP in the success rate of LMA insertion on the first attempt in adult patients undergoing general anesthesia.