DOI: 10.1097/00000539-199902001-00145
,
Issn Print: 0003-2999
Publication Date: 1999/02/01
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Excerpt
INTRODUCTION: Sepsis is a major cause of acute respiratory insufficiency (ARI). Low-volume, pressure-limited ventilation with permissive hypercapnia decreases mechanical stress of the lung and may improve outcome of patients with ARI [1]. No data are available on ventilation-perfusion (VA/Q)-relationships during mechanical ventilation with permissive hypercapnia in septic compared to non-septic patients with ARI.
METHODS: The study was approved by the ethical committee of the Ernst-Moritz-Arndt-University. 22 patients with severe ARI were studied (PaO2/FIO2 < 200 mmHg). 12 patients presented hyperdynamic septic shock (HSS) [2]. Intrapulmonary shunt (QS/QT (VA/Q < 0.005), % of QT), perfusion of areas with 0.005 < VA/Q < 0.1 (VA/Qlow, % of QT), deadspace (VD/VT (VA/Q > 100) % of VT), and the logarithmic standard deviation of VA/Q-relations of perfusion (log SDQ) were calculated from the retention and elimination of six inert gases [3]. Data were obtained during mechanical ventilation with normocapnia (NC) and with permissive hypercapnia (HC) after reduction of tidal volume by 30 %. Statistical analysis was performed by MANOVA with the post-hoc Wilcoxon-Wilcox-test and Friedmann-test. P < 0.05 was accepted as significant.
RESULTS: (Table 1, Figure 1)
DISCUSSION: Mechanical ventilation with permissive hypercapnia increased QS/QT in patients with ARI. Alterations of QS/QT were greater in subjects with hyperdynamic septic shock. There was no correlation between cardiac output and QS/QT in both groups of patients. An increased QS/QT may be due to alveolar derecruitment or impaired hypoxic pulmonary vasoconstriction. Low-volume, pressure-limited ventilation is associated with permissive hypercapnia and impaired pulmonary oxygenation due to VA/Q-inequality and increased QS/QT. The potential implications for treatment of ARI should be considered, particularly if oxygenation is seriously limited in patients with hyperdynamic septic shock.
