Hemoperfusion with an immobilized polymyxin B fiber column improves gastric mucosal pH with sepsis patients

Objective

A favorable prognosis has been reported for critically ill patients when the gastric mucosal pH (pHi) is improved at an early stage even if the pHi is low, but reports about the pHi in patients with sepsis are limited. We therefore studied the value of the pHi of sepsis patients whose global oxygen metabolism has been stabilized. In addition, we studied whether it would be able to improve the pHi of sepsis patients by using the direct hemo-perfusion with an immobilized polymyxin B fiber column (DHP-PMX).

Materials and methods

Before the start of DHP-PMX, the global oxygen metabolism and tissue oxygen metabolism were measured. A thermodilution catheter was used to determine the oxygen delivery index (DO₂I), oxygen consumption index (VO₂I), and oxygen extraction ratio (O₂ER) as parameters of global oxygen metabolism. A thermodilution catheter was also used to monitor hemodynamics and the fluid balance was managed to maintain the central venous pressure in the range of 7–10 mmHg. A gastric tonometer was used for measurement of pHi. Thirty-two patients with sepsis satisfying the following criteria were enrolled in the study: signs of systemic inflammatory response syndrome due to infection; mean arterial blood pressure >60 mmHg (irrespective of the use of catecholamines); and stable global oxygen metabolism (DO₂I > 500 ml/min/m² and VO₂I > 120 ml/min/m²). DHP-PMX was performed twice within 24 hours (for 3 hours each time). The pHi and arterial blood gases were measured four times (before DHP-PMX as well as 24, 48, and 72 hours afterward). The Sequential Organ Failure Assessment (SOFA) score was calculated before DHP-PMX. The APACHE II score was also calculated to assess the severity of each patient's condition before DHP-PMX.

Results

Twenty-six patients survived and were discharged from hospital, whereas the other six patients died. The cause of death was hepatic failure in two patients and cardiac failure in four patients. Forty-five bacterial strains were detected in 32 subjects and the most commonly isolated microorganisms were Gram-negative bacteria. DHP-PMX was performed in patients with Gram-negative or mixed Gram-negative and Gram-positive infections. Antibiotic therapy was judged to be adequate when the patient received antibiotics to which each isolated microorganism was sensitive. Although it was not possible to identify bacteria in four patients, cultures were positive in 28 patients and adequate antibiotic treatment was given to them. The SOFA score was 9.1 ± 1.0 and the APACHE II score was 20 ± 1.0 before DHP-PMX. All of the patients were on mechanical ventilation. The pHi was 7.22 ± 0.04 immediately before the start of DHP-PMX, 7.28 ± 0.03 (P = 0.036) at 24 hours afterward, 7.32 ± 0.03 (P = 0.006) at 48 hours afterward, and 7.34 ± 0.02 (P = 0.0034) at 72 hours afterward, showing a significant increase from 24 hours onward compared with the pretreatment value.

Conclusion

These findings suggest that DHP-PMX improves the pHi. This was a prospective uncontrolled observational study including a limited number of patients. The results of larger, better powered, multicenter clinical trails are necessary if we are to assess accurately the benefit of DHP-PMX.