Circulatory shock
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The hemodynamic and ultrastructural effects of lidocaine HCl pretreatment were assessed on anesthetized rats subjected to acute hemorrhagic shock. After 40 minutes of acute hemorrhagic shock (mean arterial pressure = 40 mmHg), significantly less fluid infusion was needed to return mean arterial pressure to 120 mmHg in lidocaine HCl treated animals as compared to the hemorrhagic shock-untreated group (p less than 0.05). Heart rate was significantly lower in lidocaine treated animals in the immediate post-shock period (p less than 0.05). ⋯ However, in the hemorrhagic shock-untreated group all arterial pressures were still significantly lower than their baseline values (p less than 0.05). Ultrastructural myocardial ischemic changes appeared to be less severe in the lidocaine HCl treated animals. Lidocaine HCl pretreatment improved the response to hemorrhagic shock and reinfusion in this model of hemorrhagic shock.
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To evaluate potential clinical applications of conjunctival (PcjO2) and mixed venous (SvO2) oximeters in the care of surgical patients, we compared continuous measurements of PcjO2 and SvO2 to conventional invasive hemodynamic and oxygen transport variables during normoxia, hyperoxia, hypoxia, hemorrhagic shock, and resuscitation in dogs. During the normoxic control periods, PcjO2 averaged 76% of the arterial oxygen tension (PaO2). During hyperoxia and hypoxia, PcjO2 correlated well with PaO2 values (r = 0.88) but not with mixed venous oxygen tension (PvO2), whereas the SvO2 correlated well with PvO2 (r = 0.88) but not with PaO2 values. ⋯ Both oximeters had in vivo stabilization and 90% response times of less than 2 min. We conclude that both oximetry systems are potentially useful in high-risk surgical patients to provide better cardiorespiratory surveillance and to signal the need for more intensive assessment of hemodynamic stability. This approach may lead to reduced costs from unnecessary invasive procedures as well as reduced morbidity secondary to earlier warning of cardiorespiratory compromise.
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Hypertonic saline has been used in the treatment of hypovolemic or burn shock for its rapid volemic effects. Hypertonic solutions could also improve cardiac performance and protect cellular metabolism in acute circulatory failure. We therefore studied the hemodynamic effects of continuous hypertonic saline infusion in the treatment of severe endotoxic shock in the dog. ⋯ Intravascular pressures were similar in the two groups, but cardiac output, stroke volume, and oxygen consumption were significantly higher in the hypertonic group. These results therefore indicate that hypertonic saline can rapidly restore oxygen transport and tissue oxygen consumption in septic shock. The duration of these hemodynamic effects, however, remains to be determined.