Chest
Volume 108, Issue 6, December 1995, Pages 1648-1654
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Clinical Investigations in Critical Care
Increasing Splanchnic Blood Flow in the Critically III

https://doi.org/10.1378/chest.108.6.1648Get rights and content

Study objective

To assess the effect of low dose dopexamine and dopamine on splanchnic blood flow as measured by gastric intramucosal pH, hepatic metabolism of lidocaine (lignocaine) to monoethylglycinexylidide (MEGX), and plasma disappearance rate of indocyanine green (ICG).

Design

Single-blind randomization of patients with a gastric intramucosal acidosis to receive dopexamine (ten patients), dopamine (ten patients), or saline solution (five control patients) for 2 h.

Setting

All 25 patients were in the ICU of Guys’ Hospital.

Patients

All patients met the criteria for the diagnosis of the systemic inflammatory response syndrome, were mechanically ventilated, and had pulmonary artery catheters placed. All had a low gastric intramucosal pH and had a median first 24-h acute physiology and chronic health evaluation (II) score of 22 (range, 7 to 40).

Measurements and interventions

Baseline measurements of gastric intramucosal pH, MEGX formation from lidocaine, ICG plasma disappearance rate, heart rate, mean arterial pressure, pulmonary artery occlusion pressure, cardiac index, oxygen delivery index, oxygen uptake index, systemic vascular resistance, and arterial pH were taken. Dopexamine (1 mg·kg−1·min−1), dopamine (2.5 mg·kg−1·min−1), or 0.9% saline solution was then infused for 2 h, after which a repeated set of the measurements was taken.

Results

Dopexamine at a low dose had no effect on any of the systemic measurements. The median intramucosal pH rose from 7.23 to 7.35 (p<0.005), the median ICG plasma disappearance rate from 7.6 to 11.3%·min−1 (p<0.02), and the median MEGX concentration from 4 to 10.2 ng·mL−1 (p<0.005). Dopamine had no effect on any of the measured variables. There were no changes in the control group.

Conclusions

Low-dose dopexamine increases splanchnic blood flow as measured by gastric intramucosal pH, MEGX formation from lidocaine, and ICG clearance. The lack of any change in the systemic measurements suggests that these effects are the result of a selective vasodilatation of the splanchnic vessels. At the dose used in this study, dopamine had no effect on splanchnic blood flow. Dopexamine may be useful in the management of splanchnic ischemia in the critically ill.

Section snippets

Study Population

Twenty five critically ill patients admitted to the ICU of Guy's Hospital were studied (Table 1). They all met the criteria for the diagnosis of the “systemic inflammatory response syndrome”26 and required both mechanical ventilation for acute respiratory failure and pulmonary artery catheterization for adequate hemodynamic management. They were sedated with a continuous infusion of narcotic (papaveretum or fentanyl) in combination with a benzodiazepine (midazolam) and were fully resuscitated

Results

The demographic characteristics of the patients studied are shown in Table 1. Median age was 57 years (range, 19 to 78 years) and median first 24-h APACHE II score was 22 (range, 7 to 40). The ICU mortality rate for the 25 patients was 40%, and the standardized mortality ratio (actual hospital mortality: expected mortality) was 1.08. Both dopexamine and dopamine were well tolerated and there were no deleterious effects associated with administration of lidocaine or ICG. The three groups were

Discussion

Splanchnic ischemia (affecting both the GI tract and liver) seems to be a major factor determining outcome in critically ill patients,14,28, 29, 30, 311 and it appears that gastric tonometry and the MEGX test permit the early detection of this ischemia.14,31 A number of studies have demonstrated that a low intramucosal pH (intramucosal pH), as measured by gastric tonometry, indicates inadequate splanchnic oxygenation,3, 4, 5, 6, 7, 8, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2

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    Supported by a grant awarded by the Special Trustees of Guy's Hospital.

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