Abstract
A prospective study was designed to determine serial changes in blood gas pattern and acid-base profile in 23 children with PCP. Arterial blood samples were obtained throughout acute and convalescent stage, patients breathing i) room air; ii) 100% oxygen for 15 minutes and analyzed to determine pH, PaO2, PaCO2, bicarbonate, A-aDO2 gradient and amount of venous admixture. (R-L shunt).
Initial mean values for pH, PaO2, PaCO2, bicarbonate, A-aDO2 gradient and R-L shunt were 7.49 ± 0.056, 48.2 ± 16.8, 25.2 ± 3.4, 368.2 ± 108.1 and 12.4% ± 1.8, respectively and were significantly abnormal (P<0.001). Hypoxia was present in 21 and respiratory alkalosis in 20 (uncompensated, 17, compensated, 13). Hypoxia was related to respiratory rate (r = +0.536, p<0.01).
All but one patient became more hypoxic and needed increases in inspiratory oxygen concentration (FIO2). Sixteen patients survived (2 with respirator). Survivors without respirator did not need FIO2 > 55% and showed improvement within 3.8 ± 0.5 days. Each fatal case developed progressively severe hypoxia, A-aDO2 gradient and R-L shunt and needed significantly higher FIO2 (p<0.001). At a time when clinical recovery was apparent, hypoxia was still present in 9, as were respiratory alkalosis in 7, abnormal A-aDO2 gradient and R-L shunt in 12.
We conclude that PCP produces potentially lethal alterations in blood gas and acid base profile and that these have prognostic significance. Equally important, some of these changes may persist even at the time of clinical recovery and thus, suggest residual compromise of pulmonary functions produced by the disease.
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Sanyal, S., Hughes, W. & Harris, S. ACID-BASE PROFILE AND BLOOD GAS CHANGES IN PNEUMOCYSTIS CARINII PNEUMONITIS (PCP). Pediatr Res 8, 469 (1974). https://doi.org/10.1203/00006450-197404000-00777
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DOI: https://doi.org/10.1203/00006450-197404000-00777