Utilizing the rebreathing of a gas mixture containing C2H2, C180, He O2, and N2, we obtained serial measurements of the pulmonary capillary blood flow (Qc), diffusing capacity per unit of alveolar volume (DL/VA), functional residual capacity (FRC), pulmonary tissue plus capillary blood volume (VTPC), and O2 comsumption (VO2) in five normal subjects under the following conditions: 1) 6 h of sitting, 2) 4 h of sitting while immersed in thermoneutral water to the neck, and 3) 4 h of lying in thermoneutral water to the neck. Water immersion (NI) was preceded and followed by 1-h prestudy and 1-h recovery periods. The measurements were made at 30-min intervals. Seated NI produced a fourfold increase in sodium excretion (UNaV), a 25-36% increase in Qc, a 45-59% increase in DL/VA, and a 30-36% decrease in FRC. This occurred as early as the 1st h of NI and persisted throughout the 4-h period of study. Throughout the seated control and NI periods, VO2, heart rate, and VTPC remained constant. During supine NI, Qc, HR, DL/VA, FRC, and VO2 did not differ significantly from supine prestudy. These date demonstrate that seated NI causes a significant increase of Qc and DL/VA which persists throughout the immersion period. Furthermore, the lack of change of VTPC suggests that the central vascular engorgement induced by seated NI is not accompanied by extravasation of fluid into the pulmonary interstitial space.

Fluoroquinolones are generally regarded as safe antimicrobial agents with relatively few adverse effects or drug interactions. Thus, they enjoy widespread use for treatment of community- and hospital-acquired infections. Although uncommon, hypoglycemia has been reported with all the fluoroquinolones and appears to occur most frequently in elderly patients with type 2 diabetes mellitus who are receiving therapy with oral hypoglycemics. The exact mechanism of this effect is unknown but is postulated to be a result of blockage of adenosine 5'-triphosphate-sensitive potassium channels in pancreatic beta-cell membranes. We report a case of fatal hypoglycemia related to levofloxacin administration in an elderly patient with diabetes. As with other fluoroquinolones, levofloxacin can cause profound and prolonged hypoglycemia. Clinicians should be cognizant of this potential adverse effect in patients with diabetes who are receiving levofloxacin therapy.

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Pulmonary mechanics of anesthetized dogs were not changed or were minimally altered by breathing the following compounds as submicron aerosols in concentrations up to 17.3 mg/m3 for 7.5 min: (1) sodium chloride (as a control), (2) sodium sulfate, (3) ammonium sulfate, (4) zinc sulfate, (5) zinc ammonium sulfate, (6) ammonium bisulfate, (7) aluminum sulfate, (8) manganese sulfate, (9) nickel sulfate, (10) copper sulfate, (11) ferrous sulfate, and (12) ferric sulfate. Submicron aerosols of these compounds in concentrations of 4.1-8.8 mg/m3, administered for 4 h to anesthetized dogs, did not affect mechanics of breathing, hemodynamics, and arterial blood gases. In conscious sheep, tracheal mucous velocity was not altered by exposure to the submicron aerosols of the sulfate compounds. None of these compounds, injected iv in a dose of 1 mg, had adverse effects on mechanics of breathing, pulmonary and systemic hemodynamics, or arterial blood gases. In 100-mg injections, zinc sulfate and zinc ammonium sulfate produced a fall in cardiac output, systemic hypotension, hypoxemia, and metabolic acidosis. Copper sulfate at this dose produced pulmonary hypertension, a fall in cardiac output, hypoxemia, respiratory acidosis, and a decrease of specific total respiratory conductance. It is concluded that submicron aerosols of sulfate salts do not have adverse cardiopulmonary effects when administered in high concentrations for up to 4 h. However, prolonged exposure to high concentrations of zinc sulfate, zinc ammonium sulfate, and copper sulfate aerosols should be carefully monitored because of the possibility that lower levels of these compounds in the bloodstream for long time period might have adverse cardiopulmonary effects.