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Hemodynamic effects of spontaneous breathing in the post‐operative period
Author(s) -
Neumann P.,
Schubert A.,
Heuer J.,
Hinz J.,
Quintel M.,
KlockgetherRadke A.
Publication year - 2005
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2005.00868.x
Subject(s) - medicine , stroke volume , venous return curve , anesthesia , hemodynamics , central venous pressure , ventilation (architecture) , cardiac output , respiratory rate , mechanical ventilation , heart rate , cardiology , positive airway pressure , respiratory minute volume , respiratory system , blood pressure , mechanical engineering , obstructive sleep apnea , engineering
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 (Q̇ t ). 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 Q̇ t were measured by transpulmonary thermodilution. Results: GEDV ( P = 0.055), stroke volume ( P = 0.027) and subsequently also Q̇ t ( P < 0.001) increased when spontaneous breathing increased. In contrast, no difference was observed for central venous pressure ( P = 0.19). Conclusion: The beneficial hemodynamic effects of spontaneous breathing during mechanical ventilatory support can partially be explained by improved venous return to the heart which increases stroke volume and Q̇ t .