| 1. |
- Tusman, Gerardo, et al.
(author)
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Lung recruitment and positive end-expiratory pressure have different effects on CO2 elimination in healthy and sick lungs
- 2010
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In: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 111:4, s. 968-977
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Journal article (peer-reviewed)abstract
- BACKGROUND: We studied the effects that the lung recruitment maneuver (RM) and positive end-expiratory pressure (PEEP) have on the elimination of CO(2) per breath (Vtco(2,br)). METHODS: In 7 healthy and 7 lung-lavaged pigs at constant ventilation, PEEP was increased from 0 to 18 cm H(2)O and then decreased to 0 in steps of 6 cm H(2)O every 10 minutes. Cycling RMs with plateau pressure/PEEP of 40/20 (healthy) and 50/25 (lavaged) cm H(2)O were applied for 2 minutes between 18-PEEP steps. Volumetric capnography, respiratory mechanics, blood gas, and hemodynamic data were recorded. RESULTS: In healthy lungs before the RM, Vtco(2,br) was inversely proportional to PEEP decreasing from 4.0 (3.6-4.4) mL (median and interquartile range) at 0-PEEP to 3.1 (2.8-3.4) mL at 18-PEEP (P < 0.05). After the RM, Vtco(2,br) increased from 3.3 (3-3.6) mL at 18-PEEP to 4.0 (3.5-4.5) mL at 0-PEEP (P < 0.05). In lavaged lungs before the RM, Vtco(2,br) increased initially from 2.0 (1.7-2.3) mL at 0-PEEP to 2.6 (2.2-3) mL at 12-PEEP (P < 0.05) but then decreased to 2.4 (2-2.8) mL when PEEP was increased further to 18 cm H(2)O (P < 0.05). After the RM, the highest Vtco(2,br) of 2.9 (2.1-3.7) mL was observed at 12-PEEP and then decreased to 2.5 (1.9-3.1) mL at 0-PEEP (P < 0.05). Vtco(2,br) was directly related to changes in lung perfusion, the area of gas exchange, and alveolar ventilation but inversely related to changes in dead space. CONCLUSIONS: CO(2) elimination by the lungs was dependent on PEEP and recruitment and showed major differences between healthy and lavaged lungs.
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| 2. |
- Tusman, Gerardo, et al.
(author)
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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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In: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 118:1, s. 137-144
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Journal article (peer-reviewed)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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| 3. |
- Tusman, Gerardo, et al.
(author)
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Reference values for volumetric capnography-derived non-invasive parameters in healthy individuals
- 2013
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In: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 27:3, s. 281-288
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Journal article (peer-reviewed)abstract
- The aim of this study was to determine typical values for non-invasive volumetric capnography (VCap) parameters for healthy volunteers and anesthetized individuals. VCap was obtained by a capnograph connected to the airway opening. We prospectively studied 33 healthy volunteers 32 +/- A 6 years of age weighing 70 +/- A 13 kg at a height of 171 +/- A 11 cm in the supine position. Data from these volunteers were compared with a cohort of similar healthy anesthetized patients ventilated with the following settings: tidal volume (VT) of 6-8 mL/kg, respiratory rate 10-15 bpm, PEEP of 5-6 cmH(2)O and FiO(2) of 0.5. Volunteers showed better clearance of CO2 compared to anesthetized patients as indicated by (median and interquartile range): (1) an increased elimination of CO2 per mL of VT of 0.028 (0.005) in volunteers versus 0.023 (0.003) in anesthetized patients, p < 0.05; (2) a lower normalized slope of phase III of 0.26 (0.17) in volunteers versus 0.39 (0.38) in anesthetized patients, p < 0.05; and (3) a lower Bohr dead space ratio of 0.23 (0.05) in volunteers versus 0.28 (0.05) in anesthetized patients, p < 0.05. This study presents reference values for non-invasive volumetric capnography-derived parameters in healthy individuals. Mechanical ventilation and anesthesia altered these values significantly.
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