Critical care medicine
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Critical care medicine · Jun 1984
Continuous S-vO2 measurement and oxygen transport patterns in cardiac surgery patients.
Twenty adult cardiac surgery patients with impaired ventricular function by contrast ventriculography at cardiac catheterization were monitored from before anesthesia until the time of extubation up to 12 h postoperatively. A thermodilution pulmonary artery catheter with fiberoptic channels for continuous measurement of mixed-venous oxygen saturation (S-vO2) by reflection oximetry was substituted for the usual catheter. The S-vO2 was recorded continuously along with blood pressure, cardiac filling pressures, and heart rate. ⋯ Thus, S-vO2 reflects oxygen extraction and continuous S-vO2 provides continuous quantification of global oxygen extraction. None of the other oxygen transport variables including cardiac index showed significant correlation with S-vO2. The oximetry system provides a continuous and reliable indication of mixed-venous blood oxygenation which is a continuous reflection of oxygen extraction.
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Critical care medicine · Jun 1984
Pulmonary interstitial emphysema in the premature baboon with hyaline membrane disease.
During experiments designed to develop an appropriate ventilatory strategy for high-frequency ventilation (HFV) in the premature baboon with hyaline membrane disease (HMD), we observed the development of pulmonary interstitial emphysema (PIE). Four study groups of 5 animals each received positive-pressure ventilation and positive end-expiratory pressure (PPV/PEEP) or HFV and 1 of 3 sighing techniques. ⋯ This was evident from the location of striking dilation of the distal airways and pseudocysts in areas of atelectasis. Thus, early in the course of HMD when saccular aeration is minimal, the pathogenesis of PIE is related to airway rather than alveolar rupture.
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Critical care medicine · Jun 1984
Comparative StudyPharmacokinetic assessment of immunosuppressive activity of antibiotics in human plasma by a modification of the mixed lymphocyte reaction.
Antibiotics may impair the development and expression of specific or nonspecific immune responses. Prophylactic administration of antibacterial antibiotics is widely used in ICUs. We studied the immunosuppressive activities of cefotaxime, chloramphenicol, gentamicin, metronidazole, and rifamycin as a function of time after the administration of these drugs to ICU patients, finding that the last 4 drugs had an immunosuppressive activity detectable up to 8 h by a mixed lymphocyte reaction. When these antimicrobial agents were added to normal pooled plasma in concentrations similar to those obtained in vivo, a similar degree of inhibition was observed.
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Critical care medicine · May 1984
Conjunctival and transcutaneous oxygen monitoring during cardiac arrest and cardiopulmonary resuscitation.
To define the utility of transcutaneous and conjunctival oxygen sensors in the emergency setting, we measured serial conjunctival (PcjO2) and transcutaneous (PtcO2) oxygen tensions during CPR in 11 patients. There was no significant correlation between PaO2 and PtcO2 or PcjO2. ⋯ PcjO2 responded to changes in physiologic state more rapidly than did PtcO2, with a reaction time of approximately 60 sec. Conjunctival and transcutaneous oxygen sensors provided continuous information on the effectiveness of CPR in terms of peripheral perfusion and tissue oxygenation, and were a valuable adjunct in monitoring the clinical condition of these critically ill patients.
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Critical care medicine · May 1984
Functional residual capacity and lung mechanics at different levels of mechanical ventilation.
We assessed the effects of rapid ventilatory rates (60 to 120 breath/min) and high mechanical ventilation pressures (30/5 to 40/10 cm H2O) on lung mechanics and intravascular pressures in 9 paralyzed, sedated rabbits ventilated with a time-cycled, pressure-limited flow generator (Baby bird). Measurements of tidal volume, ventilator line pressure, tracheal pressure, functional residual capacity (FRC), and arterial and venous blood pressures showed that: 68% of the peak pressure developed by the ventilator was transmitted to the trachea at 60 breath/min, 74% at 120 breath/min, and 87% when ventilation pressures were increased to 40/10 cm H2O; when the ventilatory rate and the PEEP were increased, the end-expiratory pressure in the trachea became progressively greater than that indicated on the ventilator pressure gauge; FRC increased when the PEEP and mean tracheal pressure increased; tidal volume and dynamic compliance decreased and minute ventilation increased as ventilatory rate increased; compliance decreased whenever FRC increased, and increased whenever FRC decreased; and there was little effect on mean central venous or arterial pressure. ⋯ In normal animals, this may interfere with gas exchange and pulmonary blood flow. In abnormal lungs, the gas trapping may increase FRC and improve gas exchange within the lung.