CJ Lanteri, S Kano, AW Duncan and PD Sly
Division of Clinical Sciences, Princess Margaret Hospital, Perth, Western Australia.

Congenital heart malformations are often associated with altered pulmonary hemodynamics. Lesions associated with increased pulmonary blood flow (PBF) or increased mean pulmonary artery pressure (MPAP) may in turn alter respiratory mechanics. Surgical correction of these cardiac defects frequently involves the use of cardiopulmonary bypass (CPB), during which the lung may be partially or completely atelectatic for lengthy periods, further compromising lung mechanics. The aims of this study were to document the effect of PBF on respiratory mechanics in children and to determine whether the detrimental effects of CPB were outweighed by the potentially positive effects of the corrective surgery. Twenty-three children (2-120 mo) undergoing surgery were studied while anesthetized, paralyzed, and mechanically ventilated. Pulmonary to systemic blood flow ratio was used as an index of PBF. Seventeen children had lesions associated with increased PBF (group 1), while six had decreased or normal PBF (group 2). Respiratory mechanics were measured just before the commencement of CPB and within approximately 2 h after the cessation of CPB, with the chest closed. Dynamic elastance (Ers,dyn) and resistance (RRS) were calculated from flow, volume (V), and pressure (Pao) measurements, using multiple linear regression with a volume-dependent single compartment model. Static elastance (ERS,st) was calculated from Pao and V measurements obtained when deflating the lung in steps from a maximal Pao of 30 cm H2O. ERS,dyn, ERS,st, and RRS increased significantly with increasing PBF to 220-330% predicted. There was no correlation between MPAP and respiratory mechanics. After CPB, ERS, dyn and RRS fell to normal levels in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				F. Petak, B. Babik, Z. Hantos, D. R. Morel, J.-C. Pache, C. Biton, B. Suki, and W. Habre Impact of microvascular circulation on peripheral lung stability Am J Physiol Lung Cell Mol Physiol, October 1, 2004; 287(4): L879 - L889. [Abstract] [Full Text] [PDF]

				S. A. Stayer, L. K. Diaz, D. L. East, J. N. Gouvion, T. L. Vencill, E. D. McKenzie, C. D. Fraser, and D. B. Andropoulos Changes in Respiratory Mechanics Among Infants Undergoing Heart Surgery Anesth. Analg., January 1, 2004; 98(1): 49 - 55. [Abstract] [Full Text] [PDF]

				E. Oostveen, D. MacLeod, H. Lorino, R. Farre, Z. Hantos, K. Desager, and F. Marchal The forced oscillation technique in clinical practice: methodology, recommendations and future developments Eur. Respir. J., December 1, 2003; 22(6): 1026 - 1041. [Abstract] [Full Text] [PDF]

				C. Edibam, A. J. Rutten, D. V. Collins, and A. D. Bersten Effect of Inspiratory Flow Pattern and Inspiratory to Expiratory Ratio on Nonlinear Elastic Behavior in Patients with Acute Lung Injury Am. J. Respir. Crit. Care Med., March 1, 2003; 167(5): 702 - 707. [Abstract] [Full Text] [PDF]

				B. Babik, F. Petak, T. Asztalos, Z.I. Deak, G. Bogats, and Z. Hantos Components of respiratory resistance monitored in mechanically ventilated patients Eur. Respir. J., December 1, 2002; 20(6): 1538 - 1544. [Abstract] [Full Text] [PDF]

				F. Petak, W. Habre, Z. Hantos, P. D. Sly, and D. R. Morel Effects of pulmonary vascular pressures and flow on airway and parenchymal mechanics in isolated rat lungs J Appl Physiol, January 1, 2002; 92(1): 169 - 178. [Abstract] [Full Text] [PDF]

				K. Muramatsu, K. Yukitake, M. Nakamura, I. Matsumoto, and Y. Motohiro Monitoring of nonlinear respiratory elastance using a multiple linear regression analysis Eur. Respir. J., June 1, 2001; 17(6): 1158 - 1166. [Abstract] [Full Text] [PDF]

				T. UHLIG, J. H. WILDHABER, N. CARROLL, D. J. TURNER, P. R. GRAY, N. DORE, A. L. JAMES, and P. D. SLY Pulmonary Vascular Congestion Selectively Potentiates Airway Responsiveness in Piglets Am. J. Respir. Crit. Care Med., April 1, 2000; 161(4): 1306 - 1313. [Abstract] [Full Text]