Hemodynamic effects of spontaneous breathing in the post-operative period

• Published in: Acta anaesthesiologica Scandinavica 2005-11, Vol.49 (10), p.1443-1448
• Main Authors: Neumann, P., Schubert, A., Heuer, J., Hinz, J., Quintel, M., Klockgether-Radke, A.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood Gas Analysis; Blood Volume - drug effects; Cardiac Output - drug effects; Female; gas exchange; Heart - drug effects; hemodynamics; Hemodynamics - drug effects; Humans; Male; Medical sciences; Middle Aged; Oxygen - blood; post-operative period; Postoperative Period; Pulmonary Gas Exchange; Respiratory Mechanics - physiology; spontaneous breathing; stroke volume; Stroke Volume - drug effects
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1111/j.1399-6576.2005.00868.x

Background:  During mechanical ventilatory support, spontaneous breathing has been linked to improved hemodynamics. These findings may be explained by a decrease in intrathoracic pressure which may improve venous return to the heart. Such a mechanism should result in a dose–response relation between the amount of spontaneous breathing and an increase in the global end‐diastolic volume (GEDV) and cardiac output (Q̇t). Methods:  To test this hypothesis, 15 patients were studied after major elective surgery during weaning from mechanical ventilation using bilevel positive airway pressure (BIPAP). BIPAP allows unrestricted spontaneous breathing during every phase of the respiratory cycle. Thus, ventilatory support was modified by changing the mechanical respiratory rate only, whereas inspiratory airway pressure and PEEP were kept constant. GEDV and Q̇t were measured by transpulmonary thermodilution. Results:  GEDV (P = 0.055), stroke volume (P = 0.027) and subsequently also Q̇t (P