Current status of gastrointestinal tonometry:

Endpoints of Resuscitation for the Victim of Trauma

Useful resuscitation endpoints must serve both to diagnose the need for and to ensure the ongoing adequacy of resuscitation. To this end, traditional measures of organ perfusion are now widely appreciated to be grossly inadequate. Useful endpoints or milestones range from the global, to the regional, to the cellular specific. Understanding the basic principles of perfusion-related dysoxia in trauma and hemorrhage and its potential rapid transition to involve inflammatory and immune responses on cellular oxygen utilization will aid the clinician in choosing and appropriately interpreting endpoint monitoring data. There also appears to be an optimal window of opportunity for monitoring to help mitigate the development of more complicated inflammatory states. This article reviews the underlying need for endpoint selection (both global and regional, biochemical and functional) and monitoring during resuscitation of the polytrauma patient. At this juncture it appears that early use of a blend of global markers such as lactate and base deficit coupled with an available sensitive regional monitor such as gastric tonometry may offer the best combination of current technology to guard against early perfusion-related dysoxia. Future techniques involving optical spectroscopy offer the exciting potential to assess oxygenation at the cellular level. This may aid in ultra-early detection and resolution of perfusion-related dysoxia in addition to recognizing its transition to more complex inflammatory-mediated circulatory and metabolic failure.

Organ dysfunction assessment score for severe head injury patients during brain hypothermia

The purpose of this study was to evaluate the utility of a novel organ dysfunction assessment score developed for patients with severe traumatic brain injury during therapeutic brain hypothermia. The Brain Hypothermia Organ Dysfunction Assessment (BHODA) score is calculated through the combined assessment of 6 indices: central nervous system (CNS) function, respiratory function, cardiovascular function, hepatosplanchnic circulation, coagulation, and metabolism. The CNS, hepatosplanchnic circulation, and metabolic indices were based on measurements of cerebral perfusion pressure, gastric tonometry, and blood glucose, respectively. Thirty-nine patients with severe closed head injuries (scores of 3 to 8 on the Glasgow Coma Scale) were enrolled. Seven patients (18%) died during hospitalization. Outcome was favorable in 20 patients and unfavorable in 19. The BHODA score proved useful in describing sequences of complications during therapeutic brain hypothermia. A total maximum BHODA score of more than 13 points corresponded to a mortality of 70%. In a multivariate model, the total maximum BHODA score was independently associated with neurological outcome (odds ratio for unfavorable neurological outcome, 2.590: 95% confidence interval, 1.260, 5.327). In conclusion, the BHODA score can help assess multiple organ dysfunction/failure during therapeutic hypothermia and may be useful for predicting outcome.

Tissue capnometry: does the answer lie under the tongue?

Increases in tissue partial pressure of carbon dioxide (PCO(2)) can reflect an abnormal oxygen supply to the cells, so that monitoring tissue PCO(2) may help identify circulatory abnormalities and guide their correction. Gastric tonometry aims at monitoring regional PCO(2) in the stomach, an easily accessible organ that becomes ischemic quite early when the circulatory status is jeopardized. Despite substantial initial enthusiasm, this technique has never been widely implemented due to various technical problems and artifacts during measurement. Experimental studies have suggested that sublingual PCO(2 )(P(sl)CO(2)) is a reliable marker of tissue perfusion. Clinical studies have demonstrated that high P(sl)CO(2) values and, especially, high gradients between P(sl)CO(2) and arterial PCO(2) (DeltaP(sl-a)CO(2)) are associated with impaired microcirculatory blood flow and a worse prognosis in critically ill patients. Although some questions remain to be answered about sublingual capnometry and its utility, this technique could offer new hope for tissue PCO(2) monitoring in clinical practice.

Gastric capnometry with air-automated tonometry predicts outcome in critically ill patients

CONTEXT

Contrary to tonometer gastric intramucosal pH, there is currently no validated threshold prognostic value for Pco2 gap (tonometer gastric mucosal Pco2 minus arterial Pco2) in the critically ill patient.

OBJECTIVE

To demonstrate a relationship between Pco2 gap and mortality in mechanically ventilated patients.

DESIGN AND SETTING

Inception cohort study from a 9-month prospective survey of 95 consecutively ventilated critically ill patients in a teaching hospital.

PATIENTS

All the ventilated patients of the intensive care unit were included at their admission.

MEASUREMENTS AND MAIN RESULTS

Gastric Pco2 using regional capnometry with air-automated tonometry, arterial gas, lactate, and organ system failure score were measured at admission and after 6, 12, 24, 48, 72, 96, and 120 hrs. For the entire population, the 28-day mortality was 44%. In multivariate analysis, independent predictors of death were organ system failure score (odds ratio, 2.12; 95% confidence interval, 1.02-3.14), 24-hr Pco2 gap (odds ratio, 1.57; 95% confidence interval, 1.10-2.24), and 24-hr lactate (odds ratio, 1.48; 95% confidence interval, 1.06-2.05). We found a threshold value of 20 mm Hg for Pco2 gap and 2.5 mmol/L for lactate, which was associated with a sensitivity of 0.70 and 0.72, respectively, and a specificity of 0.72 and 0.73, respectively.

CONCLUSION

The Pco2 gap is a marker of mortality in ventilated patients in the intensive care unit.