RESUMEN
This study examined the relationships between acid-base disorders, hypoxemia, electrolyte imbalances, plasma adrenaline (Ad) and noradrenaline (NAd) in 94 patients with acute severe asthma. Criteria of inclusion were [PaO2 + PaCO2/.8] less than 140 mmHg when breathing air (FiO2 = 21%) and/or PaCO2 greater than or equal to 45 mmHg. PaCO2 was closely related to H+ in those patients with hypercapnia: H+ nmol/l = 0.88 PaCO2 + 4 (r 0.91 ; n = 61; p less than 0.001). However, among the 62 acidotic cases (pH less than or equal to 7.36), 24 were classified as respiratory, 22 as mixed and 16 as metabolic. A loose though highly significant relationship was found between PaO2 and PaCO2 (when breathing air). Blood lactate, which was 3.61 +/- 1.9 mmol/l (+/- SD), was not correlated with anion gap or H+, but was loosely related to PaO2 and kalemia. Ad (1.53 +/- 1.17 nmol/l) and NAd (5.85 +/- 3.44 nmol/l), measured at the time of admission in 27 patients (FIO2 = 21%), varied significantly from those of a control group (p less than 0.01). NAd was correlated with H+, lactate and especially PaCO2, whereas no correlation could be established for Ad with these factors or NAd values. On the average, kalemia, phosphatemia and calcemia were lowered. In conclusion, mixed and metabolic acidosis were more common in this study than in a previous personal series and were not necessarily associated with an increase in blood lactate. Drugs taken prior to hospitalization must be considered in the pathophysiology of hyperlactatemia, which appears to be one among several factors linked to NAd levels.