29 Burn‐induced GI dysmotility in severe burn injury

Abstract

Introduction: Severe burn injury is known to delay gastric emptying in both animals and humans; however no data are available on its effect on gastric myoelectrical activity (GMA). We aimed at studying the effect of burn injury on GMA as it might contribute to burn‐induced delayed gastric emptying.Methods: Surgical implantation of a pair of cardiac pacemaker wires onto the stomach serosa was carried out in 20 adult male Sprague‐Dawley rats. Following recovery, GMA was recorded for 30 min in both fasting and fed conditions. The following day, rats received a sham or a 3rd degree scald burn injury under anesthesia. Proper fluid resuscitation and analgesia were given to all animals. Six hours after sham/burn injury, GMA was recorded for 30 min again in both fasting and fed conditions. A methylcellulose meal was mixed with phenol red (marker), so that the percentage of gastric emptying could be calculated based on the amount of phenol red recovered from the stomach. GMA parameters were computed using previously validated spectral analysis software developed in our laboratory, including dominant frequency/power and percentages of normal slow waves, bradygastria, tachygastria and arrhythmia. The normal slow wave frequency range was 4–6 cycles per min (cpm) in rats, while ≤4 cpm and ≥6 cpm were considered bradygastria and tachygastria respectively. Arrhythmia was established if the slow wave frequency had no specific range.Results: 1) None of GMA parameters showed any statistical differences in the fasting condition after burn (p > 0.05). 2) Significant changes in GMA with burn were only observed postprandially, including: a decrease in dominant frequency (4.5 ± 0.2 vs. 5.1 ± 0.2, p = 0.002) and in the percentage of normal slow waves (67.2 ± 7.3 vs. 84.5 ± 4.1, p = 0.02) and an increase in the percentage of bradygastria (24.7 ± 6.8 vs. 9 ± 3.9, p = 0.02). 3) The percentage of gastric emptying was decreased after burn to 40.3 ± 6.5 vs. 77 ± 3.2 in previously obtained controls (p = 0.0003); however, it did not correlate significantly to any of GMA parameters before or after burn, whether in fasting or in fed conditions (p > 0.05).Conclusion: Severe burn injury impairs both GMA and gastric emptying in rats. However, these alterations are not correlated with each other, suggesting that gastric dysrhythmia is a manifestation of burn rather than the cause of burn‐induced delayed gastric emptying.