Esophageal capnometry during hemorrhagic shock and after resuscitation in rats

Abstract

Correspondence: Dan Torbati, Dan.Torbati@MCH.Com 79 HR = heart rate; MABP = mean arterial blood pressure; PaCO 2 = arterial partial carbon dioxide tension; PCO 2 = partial carbon dioxide tension; PeCO 2 = esophageal partial carbon dioxide tension. AbstractBackground 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 steadystate 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.

Sublingual capnometry: a non-invasive measure of microcirculatory dysfunction and tissue hypoxia

“…It is likely that BE can be normal despite hypoperfusion. Furthermore, as it requires time for the liver and kidney to regenerate bicarbonate, it can be expected that there will be a long lag phase between the correction of intravascular volume deficit and normalization of the BE (Totapally et al 2003).…”

Reliable assessment of perfusion is the Holy Grail of intensive care

“…Central venous saturation has been shown to be useful and is recommended for goal-directed therapy for septic shock patients. [ 5 ] Enthusiasm for tissue oxygen saturation, gastric tonometry, and tissue arterial carbon dioxide gradient[ 6 ] as targets for endpoint of resuscitation has waned as they have not shown to improve the patient outcomes.…”