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Fig. 5 | Critical Care

Fig. 5

From: Assessment of dead-space ventilation in patients with acute respiratory distress syndrome: a prospective observational study

Fig. 5

Correlation between dead space and PaO2/FiO2 ratio. Dead space was calculated using volumetric capnography with PaCO2 (Enghoff-VCap) and PACO2 (Bohr-VCap). Dead space calculated with Enghoff-VCap shows a strong correlation (r 2 = 0.54) with PaO2/FiO2 ratio (PF ratio), whereas this correlation is weak (r 2 = 0.12) with Bohr-VCap. Thus, the use of PACO2 makes dead-space calculation less dependent on intrapulmonary shunts and diffusion impairment. PaO 2 partial pressure of oxygen in arterial blood, PaCO 2 partial pressure of carbon dioxide in arterial blood, PACO 2 partial pressure of carbon dioxide in alveolar air, PF PaO2/FiO2 ratio, V D /V T dead-space fraction

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