Functional Residual Capacity, Thoracoabdominal Dimensions, and Central Blood Volume during General Anesthesia with Muscle Paralysis and Mechanical Ventilation

• Published in: Anesthesiology (Philadelphia) Vol. 62; no. 3; pp. 247 - 254
• Main Authors: Hedenstierna, G., Strandberg, Å., Brismar, B., Lundquist, H., Svensson, L., Tokics, L.
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott 01.03.1985
• Subjects: Abdomen - anatomy & histology; Abdomen - blood supply; Abdomen - physiology; Adult; Aged; Anesthesia; Anesthesia, General; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood Gas Analysis; Blood Volume - drug effects; Body Water - metabolism; Diaphragm - physiology; Female; Functional Residual Capacity; General anesthesia. Technics. Complications. Neuromuscular blocking. Premedication. Surgical preparation. Sedation; Hemodynamics - drug effects; Humans; Intraoperative Period; Lung - metabolism; Lung Volume Measurements; Male; Medical sciences; Middle Aged; Pancuronium - pharmacology; Respiration, Artificial; Ribs - physiology; Thorax - anatomy & histology; Thorax - blood supply; Thorax - physiology; Tomography, X-Ray Computed; Human; Lung volume; Blood volume; General anesthesia; Diaphragm; Artificial ventilation; Functional residual capacity; Neuromuscular blocking
• ISSN: 0003-3022
• DOI: 10.1097/00000542-198503000-00007

Functional residual capacity (FRC), rib cage and abdominal dimensions (rc-ab), central blood volume (CBV), and extra vascular lung water (EVLW) were measured in six lung-healthy subjects awake and during halothane anesthesia, muscle paralysis, and mechanical ventilation. FRC was assessed by multiple breath nitrogen washout, rc-ab dimensions by computerized tomography, and CBV and EVLW by a double-indicator dilution technique (thermo-dye). During anesthesia, FRC decreased by 0.5 1 (17%). The cross-sectional chest area was reduced by 12-20 cm2, causing an approximate reduction in thoracic volume by 0.3 1. Concomitantly, the diaphragm was moved cranially by an average of 1.9 cm, diminishing the thoracic volume a further 0.5 1. The abdominal cross-sectional area did not alter significantly, despite the shift of the diaphragm. CBV decreased by 0.3 1. EVLW did not change significantly. It is concluded that the thoracic volume is reduced during halothane anesthesia, muscle paralysis, and mechanical ventilation as a result of cranial shift of the diaphragm and reduction in transverse area. The decrease in thoracic volume is accompanied by a reduction in FRC and a displacement of blood from the thorax to the abdomen, the transverse area of the latter thus being maintained despite the shift of the diaphragm.