Pulmonary complications of hyponatremic encephalopathy. Noncardiogenic pulmonary edema and hypercapnic respiratory failure.
OBJECTIVE
To determine the causes of hypoxia in patients with hyponatremic encephalopathy.


METHODS
Retrospective cohort study.


METHODS
Consultation and referral service of two university medical centers and community hospitals.


METHODS
Forty adults with postoperative hyponatremic encephalopathy and hypoxia of whom 30 had noncardiogenic pulmonary edema and 10 had hypercapnic respiratory failure.


METHODS
We evaluated the chest radiographs and measured plasma electrolytes, arterial blood gas values, pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP), cardiac output, and net fluid retention.


RESULTS
Forty patients with hyponatremic encephalopathy had hypoxia (arterial PO2 below 70 mm Hg), of whom 30 had pulmonary edema and 10 had hypercapnia (PCO2 above 50 mm Hg). Among the 30 patients with pulmonary edema, the serum sodium (+/- SD) was 114 +/- 7 mmol/L, arterial pH was 7.24 +/- 0.16, PCO2 was 45 +/- 15 mm Hg, and PO2 was 42 +/- 16 mm Hg. The cardiac index was 3.6 +/- 0.4 L/min/M2, pulmonary artery pressure was 26/16 mm Hg, and PCWP was 12 +/- 6 mm Hg. There was pulmonary edema, with normal heart size. The hypoxic patients who did not have pulmonary edema had significant hypercapnia (PCO2 = 91 +/- 29 mm Hg, p < 0.001).


CONCLUSIONS
Patients with postoperative hyponatremic encephalopathy can develop hypoxia by at least two different mechanisms: noncardiogenic pulmonary edema or hypercapnic respiratory failure.
Department of Medicine, Baylor College of Medicine, Houston, TX.
J C
JC
Ayus
A I
AI
Arieff
D000328:Adult; D001927:Brain Diseases / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000209:etiology*; D007010:Hyponatremia / Q000150:complications*; D000860:Hypoxia / Q000209:etiology; D008297:Male; D011183:Postoperative Complications; D011654:Pulmonary Edema / Q000209:etiology*; D012131:Respiratory Insufficiency / Q000209:etiology*; D012189:Retrospective Studies