Effect of the mechanical ventilatory cycle on thermodilution right ventricular volumes and cardiac output

• Published in: Journal of applied physiology (1985) Vol. 89; no. 1; pp. 89 - 96
• Main Authors: Groeneveld, A. B. Johan, Berendsen, Remco R, Schneider, Anton J, Pneumatikos, Ioannis A, Stokkel, Leo A, Thijs, Lambertus G
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.07.2000; American Physiological Society
• Subjects: Aged; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood Pressure - physiology; Cardiac Output - physiology; Catheterization, Swan-Ganz - standards; Critical Care; Emergency and intensive respiratory care; Female; Heart; Heart Rate - physiology; Humans; Intensive care medicine; Male; Medical sciences; Middle Aged; Reproducibility of Results; Respiration, Artificial; Respiratory Function Tests; Space life sciences; Thermodilution - standards; Ventilation; Ventricular Function, Right - physiology; Heart; Human; Assisted ventilation; Respiratory disease; Right ventricle; Respiratory system; Blood flow; Thermodilution; Blood volume; Circulatory system; Hemodynamics; Pulmonary ventilation; Respiration; Mechanical ventilation
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2000.89.1.89

1  Medical and 2  Surgical Intensive Care Unit and 3  Department of Clinical Physics, Institute for Cardiovascular Research, Free University Hospital, 1081 HV Amsterdam, The Netherlands The purpose of this study was to evaluate right ventricular (RV) loading and cardiac output changes, by using the thermodilution technique, during the mechanical ventilatory cycle. Fifteen critically ill patients on mechanical ventilation, with 5 cmH 2 O of positive end-expiratory pressure, mean respiratory frequency of 18 breaths/min, and mean tidal volume of 708 ml, were studied with help of a rapid-response thermistor RV ejection fraction pulmonary artery catheter, allowing 5-ml room-temperature 5% isotonic dextrose thermodilution measurements of cardiac index (CI), stroke volume (SV) index, RV ejection fraction (RVEF), RV end-diastolic volume (RVEDV), and RV end-systolic volume (RVESV) indexes at 10% intervals of the mechanical ventilatory cycle. The ventilatory modulation of CI and RV volumes varied from patient to patient, and the interindividual variability was greater for the latter variables. Within patients also, RV volumes were modulated more by the ventilatory cycle than CI and SV index. Around a mean value of 3.95 ± 1.18 l · min 1 · m 2 (= 100%), CI varied from 87.3 ± 5.2 (minimum) to 114.3 ± 5.1% (maximum), and RVESV index varied between 61.5 ± 17.8 and 149.3   ± 34.1% of mean 55.1 ± 17.9 ml/m 2 during the ventilatory cycle. The variations in the cycle exceeded the measurement error even though the latter was greater for RVEF and volumes than for CI and SV index. For mean values, there was an inspiratory decrease in RVEF and increase in RVESV, whereas a rise in RVEDV largely prevented a fall in SV index. We conclude that cyclic RV afterloading necessitates multiple thermodilution measurements equally spaced in the ventilatory cycle for reliable assessment of RV performance during mechanical ventilation of patients. right ventricular performance; ejection fraction catheter; critically ill; reliability of thermodilution