A New Oxygenation Index for Reflecting Intrapulmonary Shunting in Patients Undergoing Open-Heart Surgery

• Published in: Chest Vol. 125; no. 2; pp. 592 - 596
• Main Authors: El-Khatib, Mohamad F., Jamaleddine, Ghassan W.
• Format: Journal Article
• Language: English
• Published: Northbrook, IL Elsevier Inc 01.02.2004; American College of Chest Physicians
• Subjects: Adaptation, Physiological; Aged; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood Gas Analysis; Carbon Dioxide - blood; Cardiology. Vascular system; Coronary Artery Bypass - methods; Coronary Disease - diagnosis; Coronary Disease - surgery; Female; Follow-Up Studies; Hospitals, University; Humans; intrapulmonary shunt; Male; mean airway pressure; Medical sciences; Middle Aged; Monitoring, Intraoperative; open-heart surgery; Oximetry; oxygenation factor; oxygenation measurements; oxygenation ratio; Pneumology; positive end-expiratory pressure; Positive-Pressure Respiration; Postoperative Care - methods; Probability; Prospective Studies; Pulmonary Circulation - physiology; Pulmonary Gas Exchange - physiology; Respiratory Function Tests; Risk Assessment; Sensitivity and Specificity; Severity of Illness Index; Ventilation; positive end-expiratory pressure; Qsp/Qt; PEEP; P(A-a)O2; mean airway pressure; Fio2; Paw; oxygenation measurements; Pao2; intrapulmonary shunt; open-heart surgery; oxygenation factor; CABG; Cco2; ALI; oxygenation ratio; Heart; Human; Measurement; Shunt; Index; Positive end expiratory pressure; Treatment; Surgery; Anesthesia; Ratio; Circulatory system; Cardiology; Oxygenation
• ISSN: 0012-3692; 1931-3543
• DOI: 10.1378/chest.125.2.592

To assess the reliability of new and traditional oxygenation measurements in reflecting intrapulmonary shunt. Prospective study. Cardiac surgery unit at a university hospital. Fifty-five patients undergoing coronary artery bypass grafting. Simultaneous blood samples were collected from an indwelling arterial line and a catheter for determination of blood gases. Standard accepted formulas were utilized to measure a new oxygenation index: Pao2/fraction of inspired oxygen (Fio2) × mean airway pressure (Paw). The standard formulas used were the oxygenation ratio (Pao2/Fio2), Pao2/alveolar partial oxygen pressure (Pao2), alveolar-arterial oxygen tension gradient (P[A-a]O2), and intrapulmonary shunt (venous admixture [Qsp/Qt]). There were significant negative (p < 0.05) correlations between the Pao2/(Fio2 × Paw) and Qsp/Qt (r = − 0.85), between the Pao2/Fio2 and Qsp/Qt (r = − 0.74), and between the Pao2/Pao2 and Qsp/Qt (r = − 0.71). There was a significant positive (p < 0.05) correlation between the P(A-a)O2 gradient and Qsp/Qt (r = 0.66). However, the correlation was strongest between the Pao2/(Fio2 × Paw) and Qsp/Qt. In this group of patients, Pao2/(Fio2 × Paw) might be more reliable than other oxygenation measurements in reflecting intrapulmonary shunt.