Peripheral venous blood gases and pulse-oximetry in acute cardiogenic pulmonary oedema

• Published in: European heart journal. Acute cardiovascular care Vol. 1; no. 4; pp. 275 - 280
• Main Authors: Masip, J, De Mendoza, D, Planas, K, Paez, J, Sanchez, B, Cancio, B
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.12.2012
• Subjects: Acute Heart Failure; Cardiovascular diseases; Edema pulmonar; Heart failure; Insuficiència cardíaca; Malalties cardiovasculars; Oxigen en l'organisme; Oxygen in the body; Pulmonary edema; pulmonary oedema; oxygen saturation; venous blood gases; arterial blood gases; Acute heart failure
• ISSN: 2048-8726; 2048-8734
• DOI: 10.1177/2048872612457087

Background: The role of venous blood gases as an alternative to arterial blood gases in patients with severe acute heart failure has not been established. Objective: To assess the correlation between arterial and peripheral venous blood gases together with pulse-oximetry (SpO2), as well as to estimate arterial values from venous samples in the first hours upon admission of patients with acute cardiogenic pulmonary oedema. Methods: Simultaneous venous and arterial blood samples were extracted on admission and over the next 1, 2, 3, 4, and 10 hours. SpO2 was also registered at the same intervals. Results: A total of 178 pairs of samples were obtained from 34 consecutive patients with acute cardiogenic pulmonary oedema. Arterial and venous blood gases followed a parallel course in the first hours, showing high correlation rates at all time intervals. Venous samples underestimated pH (mean difference −0.028) and overestimated CO2 (+5.1 mmHg) and bicarbonate (+1 mEq/l). Conversely, SpO2 tended to underestimate SaO2 (mean±SD: 93.1±9.1 vs. 94.2±8.4). Applying simple mathematical formulae based on these differences, arterial values were empirically calculated from venous samples, showing acceptable agreement in the Bland−Altman test. Likewise, a venous pH <7.32, pCO2 >51.3 mmHg, and bicarbonate <22.8 mEq/l could fairly identify arterial acidosis, either respiratory or metabolic, with a test accuracy of 92, 68, and 91%, respectively. Conclusions: In patients with cardiogenic pulmonary oedema, arterial blood gas disturbances may be estimated from peripheral venous samples. By monitoring SpO2 simultaneously, arterial punctures could often be avoided.