Body water and plasma volume in severe community-acquired pneumonia: implications for fluid therapy.
OBJECTIVE
To determine changes in total and extracellular body water, plasma volume and sodium in children with severe and very severe pneumonia, and examine the association between these changes and oxygenation.


METHODS
Prospective, observational.


METHODS
Fifty children aged 2-59 mths with severe and very severe pneumonia.


METHODS
Serum sodium (SNa), plasma osmolality (Posm), urinary sodium (UNa) and osmolality, total body water (TBW), extracellular water (ECW) and plasma volume (PV) were estimated during the acute phase of pneumonia (within 3-6 hrs of presentation) and after recovery. These were correlated with oxygen saturation (SpO(2)) recorded on presentation.


RESULTS
All children had cough, fever, tachypnoea and chest-wall indrawing; 70% had inability to feed and 90% were hypoxaemic (SpO(2) < or = 90%). During the acute phase of illness, among the survivors (n=46), mean (SD) ECW and PV were significantly higher than that after recovery [ECW 318 (45) vs 308 (49) ml/kg, PV 53.2 (2.3) vs 52.1 (2.3) ml/kg, p<0.05]. SNa < or = 135 mmol/L was significantly correlated with ECW and PV excess. SpO(2) showed a significant linear relationship with TBW, ECW and PV (r=0.43, 0.46 and 0.42, respectively, p<0.005) and SNa (r= or <0.33, p=0.02). On multiple regression analysis, ECW, blood urea and PV were significant predictors of SpO(2) (combined r=0.63). The four patients who died had significantly higher Posm and blood urea and lower SpO(2) but in a logistic regression model SpO(2) was the only significant predictor of death (odds ratio 0.54, 95% CI 0.32-0.9, p=0.02).


CONCLUSIONS
ECW and PV were moderately increased in severe and very severe pneumonia and the increase correlated with better oxygenation. These findings suggest that fluid retention in response to hypoxaemia is directed towards improving circulating volume. The current practice of fluid restriction in hypoxaemic patients with severe pneumonia might be logical only after correction of hypoxaemia.
Singhi
Sunit
S
Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India. drsinghi@glide.net.in
Sharma
Arvind
A
Majumdar
S
S
D001834:Body Water / Q000502:physiology*; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000503:physiopathology; D005260:Female; D005440:Fluid Therapy / Q000379:methods*; D006801:Humans; D007223:Infant; D008297:Male; D009994:Osmolar Concentration; D010100:Oxygen / Q000502:physiology; D010953:Plasma Volume / Q000502:physiology*; D011014:Pneumonia / Q000503:physiopathology*; D011446:Prospective Studies; D012964:Sodium / Q000097:blood / Q000652:urine
D012964:Sodium; D010100:Oxygen