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Thorac Cardiovasc Surg 1985; 33(4): 215-217
DOI: 10.1055/s-2007-1014122
© Georg Thieme Verlag Stuttgart · New York

Hemodynamic Changes during Mechanical Ventilation in Infants and Small Children after Open Heart Surgery

V. V. Alexi-Meskhisvili, G. E. Falkowski, A. P. Nikoljuk, S. A. Popov
  • A. Bakulev Institute of Cardiovascular Surgery, Moscow, USSR
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Publication History

1985

Publication Date:
19 March 2008 (online)

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Summary

The study was undertaken to clarify the hemodynamic effects of intermittent positive pressure Ventilation (IPPV) and intermittent mandatory Ventilation (IMV) with Variation of the positive end-expiratory pressure (PEEP) from 5 to 15 mbar.

The cardiac index (CI) was measured with thermodilation techniques in 30 infants who underwent open-heart surgery with extracorporeal circulation for various congenital heart lesions. The age of the patients varied from 6 to 28 months and body weight from 4 to 15 kg.

During IPPV the changing of PEEP levels up to 5 mbar did not have any effect on Cl. Further increase in the PEEP to 10 and 15 mbar caused a significant decrease in Cl (from 2.6 to 2.0 l·min-1·m-2, p < 0.05). The oxygen consumption (VO2) did not change significantly (135 ml·min-1·m-2 to 128 l·min-1·m-2, p < 0.5). A positive end-expiratory pressure exceeding 5 mbar caused a decrease of intrapulmonary veno-arterial blood shunting (QS/QT) from 12.3 to 7.1%; p < 0.01), while PEEP at the level of 5 mbar did not affect this parameter. The alveolo-arterial oxygen gradient (AaDO2) also decreased from 182 to 135 torr (p < 0.01) when PEEP was 10 and 15 mbar.

With IMV the changes in PEEP up to 15 mbar did not cause a decrease in CI (3.2 and 3.15 ml·min-1·m-2, p < 0.05) but the oxygen consumption (VO2) increased significantly (168.4 to 198.5 ml·min-1·m-2, p < 0.05), while QS/QT decreased (10.7 to 9.4%; p < 0.05), as well as AaD02 (157.2 to 128.3 torr, p < 0.05). The increase of Cl and VO2 was noted during weaning from IPPV to all levels of PEEP studied, which was probably due to activation of the respiratory muscles and normalization of the venous blood flow to the heart.

Results obtained indicate that weaning of infants after open-heart surgery should be performed with the use of IMV and PEEP at levels that do not cause any hemodynamic disturbances.

The use of PEEP during IPPV must be strictly individualized, consideration being given to the functional State of the cardiovascular System of the operated infant.

Key words

Pediatric cardiac surgery - Postoperative care - Mechanical Ventilation - Cardiac Output

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