Critical care medicine
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Critical care medicine · Oct 1986
Comparative StudyContinuous Fick cardiac output compared to thermodilution cardiac output.
A system has been developed to monitor continuously the components of the oxygen Fick equation: oxygen consumption by a gas exchange analyzer and arteriovenous oxygen difference by pulse and fiberoptic oximetry. A computer-based system was developed which calculates cardiac output and other variables every 20 sec. Continuous Fick (CF) cardiac output was compared to thermodilution (TD) cardiac output in 21 ventilated post-cardiac surgery patients. ⋯ There was a significant (p less than .001) difference between the two methods of cardiac output estimation. The CF method was consistently lower than TD; this difference was greater at lower flows. CF cardiac output measurement is practical; it offers distinct advantages in viewing cardiac output together with oxygen demand and oxygen extraction.
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Critical care medicine · Oct 1986
Simple and accurate monitoring of end-tidal carbon dioxide tensions during high-frequency jet ventilation.
To determine whether end-tidal carbon dioxide tension (PETCO2) accurately reflects PaCO2 during high-frequency jet ventilation (HFJV), 43 studies were performed on eight mongrel dogs with normal lungs. During HFJV, minute volume was modified to obtain a range of PaCO2 values from 15.5 to 74.5 torr. ⋯ However, when the high-frequency ventilator was adjusted to deliver large tidal-volume (sigh) breaths, PETCO2 values were significantly (r = 0.94, p less than .001) correlated with PaCO2. Our data suggest that the PETCO2 of alveolar gas is an accurate indicator of the PaCO2 during HFJV in nondiseased lungs.
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Critical care medicine · Sep 1986
Computer-controlled optimization of positive end-expiratory pressure.
Positive end-expiratory pressure (PEEP) is a standard treatment for patients with refractory hypoxemia due to an acute restrictive pathology. The therapeutic range of PEEP can be quite narrow. PEEP therapy has been optimized using invasive variables such as oxygen transport and pulmonary shunt, and noninvasive variables such as compliance; however, the measurements are complex. ⋯ The CFRC and CTR algorithms reached optimal PEEP levels in 60 and 40 min, respectively, and maintained a maximal compliance for 85% of the time. This system provides fully automated noninvasive PEEP titration and is flexible enough to incorporate easily any other PEEP titration algorithms. It should improve patient care by guaranteeing that PEEP therapy is truly optimized throughout the patient's recovery.
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Critical care medicine · Aug 1986
Acute respiratory failure after cardiac surgery: clinical experience with the application of continuous arteriovenous hemofiltration.
Hemodynamic and oxygen measurements were obtained before and during 24 h of continuous arteriovenous hemofiltration (CAVH) in 36 postoperative cardiac surgery patients with severe acute pulmonary failure. During the first 6 h, the low mean arterial pressure averaged only 50 +/- 7 mm Hg; PaO2 was 90 torr on an inspired oxygen fraction of 0.86 +/- 0.03; and lactic acid was 10.5 +/- 6 mmol/L. Of the 34 patients recovering from shock within 12 h, only 24 (67%) were hospital survivors. ⋯ This treatment decreased serum levels of the myocardial depressant factor, thus allowing catecholamine support to be reduced. We conclude that CAVH eliminates cardiopulmonary toxic substances partly responsible for shock. Our patients' improved hemodynamic and respiratory function suggests that CAVH may be useful in postoperative cardiac surgery patients with respiratory and hemodynamic failure.