Effects of nitroglycerin on intestinal microcirculatory blood flow in patients with abdominal sepsis

Introduction

In sepsis, microcirculatory blood flow is impaired. Intravenous nitroglycerin (NTG) seems to have no effect on sublingual microcirculation [1], but might have a different effect on intestinal perfusion. The aim of this prospective observational sub-study was to evaluate the effect of NTG on intestinal microcirculatory flow index (MFI) compared with sublingual MFI in the early phase of sepsis.

Methods

Eight patients (>18 years) with abdominal sepsis were included. Sublingual and intestinal side-stream dark field (SDF) images were obtained and MFIs were calculated. Patients received NTG intravenously for 24 hours (2 mg/hour), after fulfillment of protocol-driven resuscitation endpoints. Nonparametric tests were used to compare MFI baseline with 24 hours and for comparison within groups. Data are expressed as median (IQR).

Results

At baseline, sublingual and intestinal MFI did not differ significantly (2.2 (1.2 to 1.8) vs 2,7 (1.1 to 2.8), P = 0.89). After 24 hours, sublingual and intestinal MFI were nonsignificantly higher in comparison with baseline (2.33 (0.48 to 3), P = 0.94 vs 2.75 (2.13 to 2.98), P = 0.67). Furthermore, groups did not differ significantly (P = 0.46). However, one patient (number 13) showed a striking decrease in sublingual MFI after 24 hours, whereas intestinal MFI did not change over time. In another patient (number 25), sublingual MFI improved with a concomitant reduction in intestinal MFI over time (Figure 1).

Figure 1

MFI with time per patient.

Conclusions

In this small population of septic patients we could not detect significant differences between the sublingual and intestinal microcirculation in response to NTG after a strict resuscitation protocol. However, in individuals there were marked differences in absolute values of sublingual and intestinal microcirculatory blood flow at baseline and after 24 hours, as well as in differences over time. These observations on dynamic microcirculatory changes in response to a specific therapeutic intervention add to previous reports about heterogeneity of microcirculatory blood flow in sepsis.