The effects of oxygen induced pulmonary vasoconstriction on bedside measurement of pulmonary gas exchange

• Published in: Journal of clinical monitoring and computing Vol. 30; no. 2; pp. 207 - 214
• Main Authors: Weinreich, Ulla M., Thomsen, Lars P., Rees, Stephen E., Rasmussen, Bodil S.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.04.2016; Springer Nature B.V
• Subjects: Aged; Anesthesiology; Automation; Breath Tests - methods; Capillary pressure; Cardiac output; Critical Care Medicine; Deoxygenation; Failure; Gas exchange; Health Sciences; Humans; Intensive; Medicine; Medicine & Public Health; Middle Aged; Original Research; Oximetry - methods; Oxygen; Oxygen - blood; Oxygen Consumption - physiology; Oxygen content; Parameter estimation; Patients; Pulmonary Artery - physiology; Pulmonary circulation; Pulmonary Gas Exchange - physiology; Pulmonary Wedge Pressure - physiology; Reproducibility of Results; Respiratory Function Tests - methods; Sensitivity and Specificity; Statistics for Life Sciences; Vascular Resistance - physiology; Vasoconstriction; Vasoconstriction - physiology; Hypoxia; Oxygen; Pulmonary vascular resistance; FiO; Hypoxic pulmonary vasoconstriction; Mean pulmonary arterial pressure; FiO2
• ISSN: 1387-1307; 1573-2614; 1573-2614
• DOI: 10.1007/s10877-015-9703-x

In patients with respiratory failure measurements of pulmonary gas exchange are of importance. The bedside automatic lung parameter estimator (ALPE) of pulmonary gas exchange is based on changes in inspired oxygen (FiO 2 ) assuming that these changes do not affect pulmonary circulation. This assumption is investigated in this study. Forty-two out of 65 patients undergoing coronary artery bypass grafting (CABG) had measurements of mean pulmonary arterial pressure (MPAP), cardiac output and pulmonary capillary wedge pressure thus enabling the calculation of pulmonary vascular resistance (PVR) at each FiO 2 level. The research version of ALPE was used and FiO 2 was step-wise reduced a median of 0.20 and ultimately returned towards baseline values, allowing 6–8 min’ steady state period at each of 4–6 levels before recording the oxygen saturation (SpO 2 ). FiO 2 reduction led to median decrease in SpO 2 from 99 to 92 %, an increase in MPAP of 4 mmHg and an increase in PVR of 36 dyn s cm −5 . Changes were immediately reversed on returning FiO 2 towards baseline. In this study changes in MPAP and PVR are small and immediately reversible consistent with small changes in pulmonary gas exchange. This indicates that mild deoxygenation induced pulmonary vasoconstriction does not have significant influences on the ALPE parameters in patients after CABG.