Pneumonia - Dehydration

 4/22/02 (Difrancesco)

Question: Is there evidence that dehydration can mask early radiographic signs of pneumonia on chest xray, that then are unmasked after hydrating the patient?

<1>

Unique Identifier:11680111

Authors: Feldman C.

Institution: Department of Medicine, Division of Pulmonology, University of the Witwatersrand, Johannesburg Hospital, Johannesburg, South Africa. 014 charl@chiron.wits.ac.za

Title: Pneumonia in the elderly. [Review] [109 refs]

Source: Medical Clinics of North America. 85(6):1441-59, 2001 Nov.

Abstract: Pneumonia, including community-acquired, LTCF-acquired, and nosocomial infections, is a major cause of morbidity and mortality among the elderly. The aged with pneumonia often present with atypical features, including confusion, lethargy, and general deterioration of condition (silent infection). Further investigations, such as a chest radiograph frequently are required for diagnosis. The chest radiograph may be normal early on in the course of infection, particularly in dehydrated patients. The elderly are hospitalized more frequently for pneumonia, have a greater need for intravenous therapy, have a longer hospital stay, have a more prolonged course, have greater morbidity, and ultimately have a poorer outcome. Nevertheless, it may not be chronologic age per se that has a negative impact on the manifestations and outcome of pneumonia in the elderly, but rather the presence of underlying comorbid illness. The mainstay of therapy for pneumonia is antibiotics, and studies in the community and hospital have confirmed the important positive impact of early appropriate empiric therapy on outcome. Many relatively simple procedures, including attention to nutrition, influenza and pneumococcal vaccination, and avoidance of intubation, may help limit the occurrence of such infections. [References: 109]

<2>

Unique Identifier:11032209

Authors: Hash RB. Stephens JL. Laurens MB. Vogel RL.

Institution: Department of Family Medicine, Mercer University School of Medicine, Macon, GA 31207, USA. hash.r@gain.mercer.edu

Title: The relationship between volume status, hydration, and radiographic findings in the diagnosis of community-acquired pneumonia.

Source: Journal of Family Practice. 49(9):833-7, 2000 Sep.

Abstract: BACKGROUND: Many clinicians believe the radiographic expression of community-acquired pneumonia (CAP) is affected by the fluid volume status of the patient. However, there are very few data to support or refute this concept. With this study we began to examine the relationship between admission fluid volume status and the radiographic expression of CAP. METHODS: Using a retrospective chart review, we examined 376 consecutive inpatient encounters with the diagnosis of pneumonia at discharge from a community teaching hospital. Patients were evaluated by age, sex, admission serum sodium, blood urea nitrogen (BUN) level, creatinine, and fluid administered in the first 48 hours of treatment. We classified these patients as either showing radiographic progression (P) or no radiographic progression (NP) by comparison of admission and follow-up radiographs. RESULTS: A total of 125 patient encounters satisfied inclusion criteria for the study. Using the Student t test we noted a statistically significant difference between the P and NP groups for BUN level (P=.02), volume of fluid administered during the first 48 hours (P=.04), and marginally for age (P=.05). The P group had higher BUN levels (mean=34 vs 24), more 48-hour fluid intake (mean=5824 mL vs 4764 mL), and younger age (mean=59 years vs 66 years) than the NP group. Logistic regression poorly predicted which patients would have worsening infiltrate on the second radiograph. CONCLUSIONS: Elevated admission BUN level and higher fluid volume administered in the first 48 hours of admission were associated with worsening radiographic findings of pneumonia after hydration. Prospective studies are needed for confirmation of our results.

<3>

Unique Identifier:3495117

Authors: Hall FM. Simon M.

Title: Occult pneumonia associated with dehydration: myth or reality.

Source: AJR. American Journal of Roentgenology. 148(5):853-4, 1987 May.

<4>

Unique Identifier:1190619

Authors: Caldwell A. Glauser FL. Smith WR. Hoshiko M. Morton ME.

Title: The effects of dehydration on the radiologic and pathologic appearance of experimental canine segmental pneumonia.

Source: American Review of Respiratory Disease. 112(5):651-6, 1975 Nov.

Abstract: In an attempt to determine whether dehydration (intravascular fluid depletion) alters the radiologic or histologic picture of segmental Streptococcus pneumoniae pneumonia, we induced pneumonia in 2 groups of dogs, group 1 (normally hydrated) and group 2 (dehydrated). Five hours after the intrabronchial instillation of a brain-heart-Streptococcus pneumoniae mixture, all chest radiographs of dogs in group 1 and 2 were compatible with segmental alveolar pneumonia. Histologic lung sections obtained as early as 2.5 hours after infusion of the brain-heart-Streptococcus pneumoniae mixture revealed intra-alveolar edema with a minimum of leukocytes. By 24 hours after infusion, both groups showed marked intra-alveolar collections of edema fluid, fibrin, and leukocytes. We conclude that in a canine model, moderate dehydration has no effect on the radiologic or histologic features of Streptococcus pneumoniae pneumonia.

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