Critical care medicine
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Critical care medicine · Dec 1981
Correction factor for thermodilution determination of cardiac output in children.
The authors determined the correction factor (Ct) for three sizes of commonly available central venous catheters. These catheters are used as the injectate catheter when a 2.5 Fr transthoracic thermistor is used to determine cardiac output by thermodilution. The valves for Ct were highly reproducible. These determinations can be used conveniently in children to determine cardiac output by thermodilution.
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Critical care medicine · Dec 1981
Continuous monitoring of interstitial fluid potassium during hemorrhagic shock in dogs.
It appears that ISFET probes can reliably and continuously monitor IF K+ in vivo for intervals of at least several hours. The consistently observed increase in IF K+ in response to hemorrhage, a phenomenon invisible systemically, suggests that such probes may provide clinically valuable information regarding perfusion related events at the cellular level during onset of and resuscitation from hypoperfusion states. Precise correlation of ISFET signal to specific cellular dysfunction awaits investigation in which muscle cell membrane potential, muscle surface pH, and postexperiment cellular histology are studied concurrently.
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Critical care medicine · Nov 1981
Contrasts between intrathoracic pressures during external chest compression and cardiac massage.
Pressures were measured in the right atrium, thoracic aorta, and pleural space during conventional cardiopulmonary resuscitation (CPR) and simultaneous ventilation compression cardiopulmonary resuscitation (SVC-CPR) in dogs, pigs, and a baboon. During both forms of closed chest resuscitation, the changes in atrial and aortic pressures were virtually identical over a range of 0-90 mm Hg and essentially equaled the change in pleural pressure measured at the most lateral portion of the chest cavity. ⋯ However, even after the chest had been opened, the hemodynamics of external chest compression could be restored by the creation of a closed, air filled cavity surrounding the heart and great vessels. Thus, elevation of intrathoracic pressure, not direct cardiac compression, is essential to and determine circulation of blood during CPR.
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Critical care medicine · Oct 1981
Transcutaneous oxygen monitoring of critically ill adults, with and without low flow shock.
One hundred and six critically ill adult patients were monitored continuously with a transcutaneous oxygen sensor (PtcO2); they also were intermittently monitored with conventional invasive hemodynamic and oxygen transport variables. A total of 1073 data sets were taken on 41 patients in the ICU and 65 patients in the operating room. The patients were divided into three groups by cardiac index (CI): relatively normal flow, CI greater than 2.2 L/min x M2; moderate low flow shock, 2.2 greater than CI greater than 1.5 L/min x M2; and severe low flow shock, CI less than 1.5 L/min x M2 x PtcO2 and arterial oxygen tension (PaO2) were compared in two ways: first by linear regression and second by a more simple clinical guide by indexing each transcutaneous value by its respective arterial value (PtcO2 index = PtcO2/PaO2). ⋯ The patients not in shock responded to changes in inspired oxygen concentration (FIO2) with changes in PaO2 and PtcO2 values; the 95% response time was approximately 2 min. The authors conclude that the normal value for PtcO2 for adult surgical patients who are hemodynamically stable is 79 +/- 12% of the PaO2 and that PtcO2 values were reliable, continuous, noninvasive trend monitors of PaO2 in these patients. During circulatory problems when PtcO2 values were compared to PaO2 values (PtcO2 index), the changes reflected trends in the severity of low flow shock.