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394 Undifferentiated abdominal pain
only been reported in abstract form. 17 Another study compared IV fentanyl with
a nebulized inhaled formulation of the same drug, and suggested similar efficacy
between the two administration routes. 25 Based upon the limited data for
fentanyl use in nontraumatic UAP, and the consistent demonstrations of fentanyl’s
safety and efficacy in adults and children with undifferentiated trauma
(many having abdominal injuries), we recommend the use of IV fentanyl when
hemodynamic concerns or need for close titration are paramount. 26–29
Both morphine and oxycodone (PO) have been specifically studied in children
with UAP. 12,20,24 Either approach appears safe and efficacious in RCTs,
but morphine offers the substantial advantage of keeping patients nil by mouth.
Whether morphine or any other opioid is administered, the need for
naloxone reversal has been rare and the serious adverse event rates have
been very low (and similar to placebo rates). 3,4 It is advisable to avoid having
to use the reversal agent, because reversal complicates patient evaluation
and renders subsequent analgesia difficult.
The mixed-mechanism agent tramadol, administered IV, has been found
efficacious for UAP in one clinical trial. 21 Based upon the paucity of current
evidence, and the efficacy of other agents with overlapping mechanisms of action,
there is no basis for recommending tramadol as a preferred agent for UAP.
The use of NSAIDs in UAP has not been well studied. Use of NSAIDs is likely
to help to alleviate any pain from stone movement. There is also evidence
basis for COX-2 inhibition as a means to moderate pain from pelvic inflammatory
disease. 30 Additionally, administration of parenteral ketorolac offers
the advantage of preserving the nil by mouth status of a patient who may
need surgery. However, there are problems with giving NSAIDs to patients
with potential need for operative intervention. The issue of NSAID-associated
operative bleeding is discussed in the chapter on biliary colic, but the
message for UAP is that there is no reason to withhold opioids and run
even a small (but preventable) risk of bleeding complications. 31,32
n Summary and recommendations
First line: morphine (initial dose 4–6 mg IV, then titrate)
Reasonable: any opioid (no advantage to use of meperidine)