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H2 blockers in the intensive care unit: ignoring the evidence? Telephone survey

^a Department of Intensive Care Guy's Hospital London SE1 9RT

Correspondence to: Dr Wyncoll

	Introduction

Top Introduction Methods and results Comment References

Stress ulcers are gastroduodenal erosions that occur commonly in critically ill patients. Although once thought to be due to excess acid production, they are now thought to result from gastric mucosal ischaemia and the value of using pH altering drugs to prevent them has been questioned.¹ Cook et al showed that only critically ill patients who have a coagulopathy or who are ventilated for more than 48 hours are at increased risk of developing serious bleeding due to stress ulceration.² Prophylaxis is usually with either an H2 receptor antagonist or sucralfate, and these agents appear equally efficacious in terms of reducing bleeding complications.³ A recent meta-analysis has, however, shown that sucralfate is associated with a lower incidence of pneumonia and mortality than H2 receptor antagonists.⁴ In spite of this, patients referred to Guy's from other intensive care units have often received H2 receptor antagonists for prophylaxis, and this survey was undertaken to quantify the extent of this practice.

	Methods and results

Top Introduction Methods and results Comment References

In March 1996 we performed a structured telephone survey of 67 intensive care units in the Thames regions. If respondents were too busy to provide accurate information a repeat call was made. Four questions were put to the senior nurse or doctor in charge: (1) Does your intensive care unit have a protocol for stress ulcer prophylaxis? (2) Which agent is used most commonly for prophylaxis in your unit? (3) How many patients are there in your unit today? (4) How many of these patients are receiving sucralfate, an H2 receptor antagonist, omeprazole, no prophylaxis?

On the day of the audit 312 patients were in the 67 units: 118 (38%) patients were receiving an H2 receptor antagonist, 82 (26%) sucralfate, 3 (1%) omeprazole, and 110 (35%) no prophylaxis (one patient was receiving both sucralfate and an H2 receptor antagonist.) The 28 units that had a protocol for stress ulceration prophylaxis were more likely to prefer sucralfate to H2 receptor antagonists than those without a protocol, as were the 13 teaching hospitals (table 1).

	Comment

Top Introduction Methods and results Comment References

Serious bleeding due to stress ulceration is defined as a drop in haemoglobin of greater than 20 g/1 accompanied by either haemodynamic instability or the need for blood transfusion.² Although the incidence of bleeding is declining, it is associated with a mortality approaching 50%. This reduction may be due to pharmacological prophylaxis, but other factors such as improved resuscitation and early enteral nutrition are likely to be equally important.

Several adverse effects have been linked to the use of H2 receptor antagonists in intensive care units, particularly an increased incidence of nosocomial pneumonia, which is associated with a mortality of 40-70% in critically ill patients.⁵ By raising intragastric pH, H2 receptor antagonists promote bacterial colonisation and overgrowth within the stomach, and hence provide a potential reservoir of infection for the respiratory tract. Sucralfate does not raise intragastric pH but enhances mucosal blood flow, stimulates bicarbonate and mucous secretion, and may be bactericidal.

Our survey shows that many intensive care units, particularly those in district hospitals and those without a protocol for stress ulcer prophylaxis, continue to use H2 receptor antagonists in preference to sucralfate. Given the known detrimental effects of H2 receptor antagonists, it is disappointing that their use is so prevalent. If the principles of evidence based medicine were followed this would no longer be so, and the morbidity and mortality of critically ill patients might be reduced.

	Acknowledgements

Funding: None.

Conflict of interest: None.

	References

Top Introduction Methods and results Comment References

1. Navab F, Steingrub J. Stress ulcer: is routine prophylaxis necessary? Am J Gastroenterol 1995;90:708-12.
2. Cook DJ, Fuller HD, Guyatt GH, Marshall JC, Leasa D, Hall R, et al. Risk factors for gastrointestinal bleeding in critically ill patients. N Engl J Med 1994;330:377-81.
3. Tryba M. Sucralfate versus antacids or H2-antagonists for stress ulcer prophylaxis: A meta-analysis on efficacy and pneumonia rate. Crit Care Med 1991;19:942-9.
4. Cook DJ, Reeve BK, Guyatt GH, Heyland DK, Griffin LE, Buckingham L, et al. Stress ulcer prophylaxis in critically ill patients. Resolving discordant meta-analyses. JAMA 1996;275:308-13. [Abstract/Free Full Text]
5. Fagon JY, Chastre J, Hance AJ, Montravers P, Novara A, Gilbert C. Nosocomial pneumonia in ventilated patients: a cohort study evaluating attributable mortality and hospital stay. Am J Med 1993;94:281-8.

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This article has been cited by other articles:

• Cook, T M (1997). Criticism of prophylaxis of gastrointestinal bleeding with H2 receptor antagonists is wrong. BMJ 315: 371-372 [Full text]