Critical care medicine
-
Critical care medicine · Nov 2000
Comparative StudyPediatric cardiac output measurement using surface integration of velocity vectors: an in vivo validation study.
To test the accuracy and reproducibility of systemic cardiac output (CO) measurements using surface integration of velocity vectors (SIVV) in a pediatric animal model with hemodynamic instability and to compare SIVV with traditional pulsed-wave Doppler measurements. ⋯ SIVV is an accurate and reproducible flow measurement technique. It is a considerable improvement over currently used methods and is applicable to pediatric critical care.
-
Critical care medicine · Nov 2000
Estimating cardiac filling pressure in mechanically ventilated patients with hyperinflation.
When positive end-expiratory pressure (PEEP) is applied, the intracavitary left ventricular end-diastolic pressure (LVEDP) exceeds the LV filling pressure because pericardial pressure exceeds 0 at end-expiration. Under those conditions, the LV filling pressure is itself better reflected by the transmural LVEDP (tLVEDP) (LVEDP minus pericardial pressure). By extension, end-expiratory pulmonary artery occlusion pressure (eePAOP), as an estimate of end-expiratory LVEDP, overestimates LV filling pressure when pericardial pressure is >0, because it occurs when PEEP is present. We hypothesized that LV filling pressure could be measured from eePAOP by also knowing the proportional transmission of alveolar pressure to pulmonary vessels calculated as index of transmission = (end-inspiratory PAOP--eePAOP)/(plateau pressure--total PEEP). We calculated transmural pulmonary artery occlusion pressure (tPAOP) with this equation: tPAOP = eePAOP--(index of transmission x total PEEP). We compared tPAOP with airway disconnection nadir PAOP measured during rapid airway disconnection in subjects undergoing PEEP with and without evidence of dynamic pulmonary hyperinflation. ⋯ Indexing the transmission of proportional alveolar pressure to PAOP in the estimation of LV filling pressure is equivalent to the nadir method in patients without dynamic pulmonary hyperinflation and may be more reliable than the nadir PAOP method in patients with dynamic pulmonary hyperinflation.
-
Critical care medicine · Nov 2000
Comparative StudyAn improved in vivo rat model for the study of mechanical ventilatory support effects on organs distal to the lung.
To study the influence of different mechanical ventilatory support strategies on organs distal to the lung, we developed an in vivo rat model, in which the effects of different tidal volume values can be studied while maintaining other indexes. ⋯ We conclude that it is possible to study the effects of mechanical ventilatory support on organs distal to the lung by means of an in vivo rat model.
-
Critical care medicine · Nov 2000
Efficacy of interposed abdominal compression-cardiopulmonary resuscitation (CPR), active compression and decompression-CPR and Lifestick CPR: basic physiology in a spreadsheet model.
This study was undertaken to understand and predict results of experimental cardiopulmonary resuscitation (CPR) techniques involving compression and decompression of either the chest or the abdomen. Simple mathematical models of the adult human circulation were used. ⋯ Interposed abdominal compression-CPR, active compression and decompression of the chest, and Lifestick CPR, which combines interposed abdominal compression and active compression and decompression, produce, respectively, 1.9-, 1.2-, and 2.4-fold greater blood flow than standard CPR and systemic perfusion pressures of 45, 30, and 58 mm Hg, respectively. These positive effects are explained by improved pump priming and are consequences of fundamental principles of cardiovascular physiology.
-
Critical care medicine · Nov 2000
Procalcitonin release patterns in a baboon model of trauma and sepsis: relationship to cytokines and neopterin.
Procalcitonin (PCT) has been described as an early, discriminating marker of bacteria-associated sepsis in patients. However, little is known of its source and actions, in part because no appropriate animal models have been available. We tested the hypothesis that plasma PCT increases during various pathophysiological conditions, such as hemorrhagic shock and sepsis, which differ with regard to the degree of associated endotoxemia. We further hypothesized that in sepsis, PCT would be significantly different in survivors vs. nonsurvivors. ⋯ PCT is detectable in the baboon as in humans, both in hemorrhagic shock and sepsis. PCT levels are significantly higher in sepsis than in hemorrhage, a finding that is probably related to the differences in endotoxin. The baboon can be used for the study of PCT kinetics in both models; PCT kinetics are clearly different from other markers of sepsis, either IL-6 or neopterin, in both models. There are significant differences between survivors and nonsurvivors in the sepsis model.