Chest
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To determine the individual contributions of variables in the Fick equation to cardiac output, we simultaneously measured oxygen uptake (VO2), carbon dioxide production (VCO2), venous oxygen saturation (SvO2) and thermodilution cardiac output (Qth) in 28 medical and surgical ICU patients. Patients were intubated and ventilated with the intermittent mandatory ventilation mode. VO2 and VCO2 (averaged over 3 min) were obtained from a metabolic cart. ⋯ None of the above oximetry relationships were substantially altered by use of COoximetry venous oxygen saturations. We conclude that Qth cannot be predicted well solely from VO2, VCO2, or SvO2 nor can changes in Qth be predicted well solely from changes in VO2, VCO2, or SvO2. Of the metabolic variables, changes in VCO2 best predicted changes in Qth.
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Comparative Study
Bronchial responsiveness to ultrasonic fog in occupational asthma due to toluene diisocyanate.
To determine the validity of ultrasonic nebulization of distilled water (UNDW, "fog") in comparison with methacholine challenge, in the assessment of toluene diisocyanate (TDI) asthma, we evaluated 75 subjects exposed to TDI with work-related respiratory symptoms. Subjects were submitted to bronchial challenge with methacholine at first, thereafter to UNDW inhalation and to specific challenge with TDI. The diagnosis of TDI-asthma was made in 30 of 75 patients (40 percent) who developed a bronchoconstrictive response to the specific challenge (reactors). ⋯ Instead, combining UNDW and methacholine challenge when methacholine is positive improves our ability in identifying subjects with TDI-asthma diagnosed with the specific challenge. This procedure constitutes a first objective confirmation of a suggestive history of TDI-asthma that is useful for clinical purposes. However, especially for medicolegal purposes, the definitive diagnosis requires the specific challenge.
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Comparative Study
Pathogenesis of Cheyne-Stokes respiration in patients with congestive heart failure. Relationship to arterial PCO2.
In order to determine which patients with congestive heart failure (CHF) develop Cheyne-Stokes respiration (CSR) during sleep, we compared the cardiorespiratory profiles of CHF patients with CSR to those of CHF patients without CSR. Overnight polysomnography and continuous transcutaneous PCO2 (tc PCO2) monitoring, estimation of left ventricular ejection fraction (LVEF), pulmonary function tests, and chest radiograph were performed on 16 consecutive patients with chronic, stable CHF. The tc PCO2 monitor (Kontron 7640) was calibrated so that measurements reflected arterial PCO2 values. ⋯ The tc PCO2 (W) was lower in group 1 (34.4 +/- 3.5 vs 38.1 +/- 1.9 mm Hg), increased during sleep by a similar amount in both groups (1.6 +/- 1.5 vs 2.1 +/- 2.2 mm Hg), and was significantly lower during sleep in group 1 (36.1 +/- 3.4 vs 40.2 +/- 2.2 mm Hg). We conclude that CHF patients with CSR hyperventilate during sleep and wakefulness and that CHF patients with awake hypocapnia are more likely to develop CSR during sleep. These findings indicate that arterial PCO2 is important in determining which CHF patients develop CSR.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparative evaluation of propofol and midazolam as sedative agents in fiberoptic bronchoscopy.
Propofol, a new intravenous sedative agent, was investigated in 41 asthmatic patients undergoing day-case (outpatient) fiberoptic bronchoscopy. The study design was a randomized comparison between propofol and midazolam, which is a well-established intravenous sedative agent. The age, weight, and American Society of Anesthesiologists physical status and lung function of the two groups were not significantly different. ⋯ Alertness scored with the digital symbol substitution test (DSST) returned to prebronchoscopy values in the propofol group at 30 min, DSST score = 35.9 (18.2) vs 13.4 (9.1), in the midazolam group (p < .0001) and was still significantly higher at 90 min-39.4 (17.9) and 23.1 (13.8) (p < 0.01). We conclude that propofol is a useful sedating agent in fiberoptic bronchoscopy with similar efficacy to midazolam but with a faster onset of action and a more rapid recovery. These represent significant advantages for day-case procedures.
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To define the influence of prior antibiotic use on the etiology and mortality of ventilator-associated pneumonia (VAP). ⋯ Distribution of infecting microorganisms responsible for VAP differs in patients who received prior antimicrobial therapy, and this factor determines a higher mortality rate. We suggest a restrictive antibiotic policy in mechanically ventilated patients with the purpose of reducing the risk of death from VAP.