Esophageal capnometry during hemorrhagic shock and after resuscitation in rats

BACKGROUND: Splanchnic perfusion following hypovolemic shock is an important marker of adequate resuscitation. We tested whether the gap between esophageal partial carbon dioxide tension (PeCO(2)) and arterial partial carbon dioxide tension (PaCO(2)) is increased during graded hemorrhagic hypotension and reversed after blood reinfusion, using a fiberoptic carbon dioxide sensor. MATERIALS AND METHOD: Ten Sprague–Dawley rats were anesthetized, tracheotomized, and cannulated in one femoral artery and vein. A calibrated fiberoptic PCO(2 )probe was inserted into the distal third of the esophagus for determination of luminal PeCO(2 )during maintained anesthesia (pentobarbital 15 mg/kg per hour), normothermia (38 ± 0.5°C), and fluid balance (saline 5 ml/kg per hour). Three out of 10 rats were used to determine the limits of hemodynamic stability during gradual hemorrhage. Seven of the 10 rats were then subjected to mild and severe hemorrhage (15 and 20–25 ml/kg, respectively). Thirty minutes after severe hemorrhage, these rats were resuscitated by reinfusion of the shed blood. Arterial gas exchange, hemodynamic variables, and PeCO(2 )were recorded at each steady-state level of hemorrhage (at 30 and 60 min) and after resuscitation. RESULTS: The PeCO(2)–PaCO(2 )gap was significantly increased after mild and severe hemorrhage and returned to baseline (prehemorrhagic) values following blood reinfusion. Base deficit increased significantly following severe hemorrhage and remained significantly elevated after blood reinfusion. Significant correlations were found between base deficit and PeCO(2)–PaCO(2 )(P < 0.002) and PeCO(2 )(P < 0.022). Blood bicarbonate concentration decreased significantly following mild and severe hemorrhage, but its recovery was not complete at 60 min after blood reinfusion. CONCLUSION: Esophageal–arterial PCO(2 )gap increases during graded hemorrhagic hypotension and returns to baseline value after resuscitation without complete reversal of the base deficit. These data suggest that esophageal capnometry could be used as an alternative for gastric tonometry during management of hypovolemic shock

Cardiovascular stability during arteriovenous extracorporeal therapy: a randomized controlled study in lambs with acute lung injury

INTRODUCTION: Clinical application of arteriovenous (AV) extracorporeal membrane oxygenation (ECMO) requires assessment of cardiovascular ability to respond adequately to the presence of an AV shunt in the face of acute lung injury (ALI). This ability may be age dependent and vary with the experimental model. We studied cardiovascular stability in a lamb model of severe ALI, comparing conventional mechanical ventilation (CMV) with AV-ECMO therapy. METHODS: Seventeen lambs were anesthetized, tracheotomized, paralyzed, and ventilated to maintain normocapnia. Femoral and jugular veins, and femoral and carotid arteries were instrumented for the AV-ECMO circuit, systemic and pulmonary artery blood pressure monitoring, gas exchange, and cardiac output determination (thermodilution technique). A severe ALI (arterial oxygen tension/inspired fractional oxygen <200) was induced by lung lavage (repeated three times, each with 5 ml/kg saline) followed by tracheal instillation of 2.5 ml/kg of 0.1 N HCl. Lambs were consecutively assigned to CMV treatment (n = 8) or CMV plus AV-ECMO therapy using up to 15% of the cardiac output for the AV shunt flow during a 6-hour study period (n = 9). The outcome measures were the degree of inotropic and ventilator support needed to maintain hemodynamic stability and normocapnia, respectively. RESULTS: Five of the nine lambs subjected to AV-ECMO therapy (56%) died before completion of the 6-hour study period, as compared with two out of eight lambs (25%) in the CMV group (P > 0.05; Fisher's exact test). Surviving and nonsurviving lambs in the AV-ECMO group, unlike the CMV group, required continuous volume expansion and inotropic support (P < 0.001; Fisher's exact test). Lambs in the AV-ECMO group were able to maintain normocapnia with a maximum of 30% reduction in the minute ventilation, as compared with the CMV group (P < 0.05). CONCLUSION: AV-ECMO therapy in lambs subjected to severe ALI requires continuous hemodynamic support to maintain cardiovascular stability and normocapnia, as compared with lambs receiving CMV support

Transport of Critically Ill Children on Cardiopulmonary Support Assistance

Objective: To report two patients helicopter transport on mechanical cardiopulmonary support to a transplant center. Setting: Cardiac intensive care unit (CICU) and transport helicopter. Patients: A 9 kg and 22 kg children who suffer cardiac deterioration needing air transport on mechanical cardiopulmonary support. Interventions and Results: CPS was initiated to support these patients failing cardiac function. Transport on CPS of these two patients to a transplant institution was accomplished after determining that heart transplantation would be their more likely chance for recovery. Conclusion: A cardiac deterioration event that will lead to the need for heart transplantation can be acute and sudden sparing no time for early referral to a transplant center. It is necessary for heart centers to have a plan of action to provide inter-hospital transport on cardiopulmonary support (CPS). This protocol can involve transport by the refer ral institution, the receiving institution or a third institution

Culture Negative Stent Infection in an Infant with Hypoplastic Left Heart and Persistent Fever

We present an infant with hypoplastic left heart with persistent fever despite two courses of antibiotics and repeatedly negative blood cultures. He eventually underwent surgical extraction of two stents. The stent cultures became positive; he was treated with 4 weeks of antibiotics and the fever resolved