sinaiem.org

Thanks to Bing, Dr. Okuda and Dr. Strother for a wonderful day of sim cases this week. Special thanks to all who had to tolerate my acting.

A few questions came up during the discussions, and, I’ve been trying to research with limited success.

The first question concerned antibiotics for heat illness. Certainly in ambiguous cases, where there is altered mental status with moderately high temperature, antibiotic coverage is mandated. But in our case, of the athlete on a hot day? It was asserted that the heat stress leads to gut flora dissemination, and antibiotics are warranted. But I could find no reference for this, and my usual sources are silent on the issue of prophylactic antibiotics.

The second question revolved around safety factors for emergent sedation. Specifically, I wondered if the risk of aspiration in emergent procedural sedation had been quantified in adults. It turns out there’s a lot of opinion on this matter, but not a lot of data. More below: Last year in Annals (Volume 49, Issue 4, April 2007, Pages 465-467) Green et al published a consensus-based practice advisory (PMID 17083995) that stated the following:

Much of the current understanding of aspiration risk is extrapolated from the general anesthesia literature, wherein the overall incidence of aspiration is low (1:3,420) and its subsequent mortality rare (1:125,109).19 There is reason to believe that aspiration risk with procedural sedation and analgesia is less likely, for reasons discussed in detail elsewhere.19

A compilation of anecdotal adverse sedation events assembled by anesthesiologists to evaluate current sedation practices by other specialists failed to identify a single case of aspiration outside of the operating room during a 27-year study period.38 Thus, there is insufficient evidence to support the position that fasting guidelines crafted for operative anesthesia should be extrapolated to sedation practice.9

They proceeded to issue reasonable guidelines based on the patient’s risk and size of recent meal; a nice table can be found on emcrit.org.

A recent Scandanavian anesthesiology review (Acta Anaesthesiol Scand. 2005 Sep;49(8):1041-7) on pre-procedure fasting (they’re liberalizing their guidelines to allow clears up to 2h pre-op in healthy elective patients, yay) also touched upon emergency procedures:

An increasing number of surgical procedures are done with ‘light, conscious or deep sedation’ in various combinations with local and regional anaesthesia. Should these patients be included in the preoperative fasting guidelines? Sedation and analgesics tend to impair airway reflexes in proportion to the degree of sedation/analgesia achieved (51, 52).

The available literature does not provide sufficient evidence to conclude that pre-procedure fasting results in a decreased incidence of adverse outcomes in patients undergoing either moderate or deep sedation. However, the American Society of anesthesiologists recommends that patients undergoing sedation/analgesia for elective procedures should have the same restrictions as patients undergoing general anaesthesia (52). These guidelines are arbitrary and based upon consensus opinion. In emergency situations, the potential for pulmonary aspiration of gastric contents must be considered. Green et al. (51) found that pulmonary aspiration during emergency department procedural sedation and analgesia had not been reported in medical literature. Therefore, there is little evidence to support specific fasting periods.

If any of this sounds familiar, it’s because it hasn’t changed since the ACEP clinical policy of 2005:

Thorough reviews of this topic demonstrate a lack of evidence that gastric emptying has any impact on the incidence of complications or on outcome in procedural sedation and analgesia. A prospective observational study of 1,014 children identified no difference with airway complications, emesis, or other adverse events between patients classified by their preprocedural fasting status.

Of the 509 (56%) patients who did not meet preprocedural fasting guidelines for elective procedures as suggested by the American Academy of Pediatrics and the American Society of Anesthesiologists, no episodes of aspiration were documented. The authors correctly acknowledge that the study is underpowered to detect significant differences in the rate of emesis with and without aspiration due to the extremely rare incidence of these combined events.35 Despite the paucity of data and in recognition of the potential risk for aspiration, a number of publications encourage careful consideration of timing and depth of procedural sedation and analgesia in the absence of an adequate fasting period.32,41,42 In addition, pharmacologic agents including antacids have not been shown to improve outcomes and are no longer recommended as standard practice.32,41,43 No study has determined a necessary fasting period before initiation of procedural sedation and analgesia.

There is insufficient evidence to determine absolute recommendations. Although recent food intake is not a contraindication for administering procedural sedation and analgesia, the emergency physician must weigh the risk of pulmonary aspiration and the benefits of providing procedural sedation and analgesia in accordance with the needs of each individual patient.

Incidentally, the ACEP review also makes no recommendations for routine pre-sedation diagnostic testing  — the risk assessment should be exam- and history-driven, and based on the patient’s status.

If anyone has some insight into the above topics, or has other observations or questions on the Sim sessions, please comment below!

Posted on Thursday, July 31st, 2008 at 2:20 pm by Nick. Filed under Post-Conference Letter, Risk Stratification, Infectious Disease, Procedures, Blog.
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