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- Tusman, Gerardo, et al.
(författare)
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Noninvasive Monitoring of Lung Recruitment Maneuvers in Morbidly Obese Patients : The Role of Pulse Oximetry and Volumetric Capnography
- 2014
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Ingår i: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 118:1, s. 137-144
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We conducted this study to determine whether pulse oximetry and volumetric capnography (VCap) can determine the opening and closing pressures of lungs of anesthetized morbidly obese patients. METHODS: Twenty morbidly obese patients undergoing laparoscopic bariatric surgery with capnoperitoneum were studied. A lung recruitment maneuver was performed in pressure control ventilation as follows: (1) During an ascending limb, the lungs' opening pressure was detected. After increasing positive end-expiratory pressure (PEEP) from 8 to 16 cm H2O, fraction of inspired oxygen (Fio(2)) was decreased until pulse oximetric arterial saturation (Spo(2)) was <92%. Thereafter, end-inspiratory pressure was increased in steps of 2 cm H2O, from 36 to a maximum of 50 cm H2O. The opening pressure was attained when Spo(2) exceeded 97%. (2) During a subsequent decreasing limb, the lungs' closing pressure was identified. PEEP was decreased from 22 to 10 cm H2O in steps of 2 cm H2O. The closing pressure was determined as the PEEP value at which respiratory compliance decreased from its maximum value. We continuously recorded lung mechanics, Spo(2), and VCap. RESULTS: The lungs' opening pressures were detected at 44 (4) cm H2O (median and interquartile range) and the closing pressure at 14 (2) cm H2O. Therefore, the level of PEEP that kept the lungs without collapse was found to be 16 (3) cm H2O. Using respiratory compliance as a reference, receiver operating characteristic analysis showed that Spo(2) (area under the curve [AUC] 0.80 [SE 0.07], sensitivity 0.65, and specificity 0.94), the elimination of CO2 per breath (AUC 0.91 [SE 0.05], sensitivity 0.85, and specificity 0.98), and Bohr's dead space (AUC 0.83 [SE 0.06], sensitivity 0.70, and specificity 0.95] were relatively accurate for detecting lung collapse during the decreasing limb of a recruitment maneuver. CONCLUSIONS: Lung recruitment in morbidly obese patients could be effectively monitored by combining noninvasive pulse oximetry and VCap. Spo(2), the elimination of CO2, and Bohr's dead space detected the individual's opening and closing pressures.
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| 2. |
- Tusman, Gerardo, et al.
(författare)
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The Sensitivity and Specificity of Pulmonary Carbon Dioxide Elimination for Noninvasive Assessment of Fluid Responsiveness
- 2016
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Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 122:5, s. 1404-1411
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We sought to determine whether the response of pulmonary elimination of CO2 (Vco(2)) to a sudden increase in positive end-expiratory pressure (PEEP) could predict fluid responsiveness and serve as a noninvasive surrogate for cardiac index (CI). METHODS: Fifty-two patients undergoing cardiovascular surgery were included in this study. By using a constant-flow ventilation mode, we performed a PEEP challenge of 1-minute increase in PEEP from 5 to 10 cm H2O. At PEEP of 5 cm H2O, patients were preloaded with 500 mL IV saline solution after which a second PEEP challenge was performed. Patients in whom fluid administration increased CI by >= 15% from the individual baseline value were defined as volume responders. Beat-by-beat CI was derived from arterial pulse contour analysis, and breath-by-breath Vco(2) data were collected during the protocol. The sensitivity and specificity of Vco(2) for detecting the fluid responders according to CI was performed by the receiver operating characteristic curves. RESULTS: Twenty-one of 52 patients were identified as fluid responders (40%). The PEEP maneuver before fluid administration decreased CI from 2.65 +/- 0.34 to 2.21 +/- 0.32 L/min/m(2) (P = 0.0011) and Vco(2) from 150 +/- 23 to 123 +/- 23 mL/min (P = 0.0036) in responders, whereas the changes in CI and Vco(2) were not significant in nonresponders. The PEEP challenge after fluid administration induced no significant changes in CI and Vco(2), in neither responders nor nonresponders. PEEP-induced decreases in CI and Vco(2) before fluid administration were well correlated (r(2) = 0.75, P < 0.0001) but not thereafter. The area under the receiver operating characteristic curves for a PEEP-induced decrease in Delta CI and Delta Vco(2) was 0.99, with a 95% confidence interval from 0.96 to 0.99 for Delta CI and from 0.97 to 0.99 for Delta Vco(2). During the PEEP challenge, a decrease in Vco(2) by 11% predicted fluid responsiveness with a sensitivity of 0.90 (95% confidence interval, 0.87-0.93) and a specificity of 0.95 (95% confidence interval, 0.92-0.98). CONCLUSIONS: PEEP-induced changes in Vco(2) predicted fluid responsiveness with accuracy in patients undergoing cardiac surgery.
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