Midazolam for PONV

From Wick, Elizabeth, and Christopher L. Wu. “The Effect of Intravenous Midazolam on Postoperative Nausea and Vomiting: A Meta-Analysis.” (2015).

The gist: Midaz at any point reduces PONV by up to 40%!

BACKGROUND: Research has shown that high-risk surgical patients benefit from a multimodal therapeutic approach to prevent postoperative nausea and vomiting (PONV). Our group sought to investigate the effect of administering IV midazolam on PONV.
METHODS: This meta-analysis included 12 randomized controlled trials (n = 841) of adults undergoing a variety of surgical procedures that investigated the effect of both preoperative and intraoperative IV midazolam on PONV in patients undergoing general anesthesia.
RESULTS: Administration of IV midazolam was associated with significantly reduced PONV (risk ratio [RR] = 0.55; 95% confidence interval [CI], 0.43–0.70), nausea (RR = 0.62; 95% CI, 0.40–0.94), vomiting (RR = 0.61; 95% CI, 0.45–0.82), and rescue antiemetic administration (RR = 0.49; 95% CI, 0.37–0.65) within 24 hours. Individual subgroup analyses of trials excluding the use of thiopental for induction, trials of either female sex or high-risk surgery, trials involving nitrous oxide maintenance, and trials using midazolam in combination with known antiemetics all yielded similar reductions in PONV end points within 24 hours of surgery.
CONCLUSIONS: Administration of preoperative or intraoperative IV midazolam is associated with a significant decrease in overall PONV, nausea, vomiting, and rescue antiemetic use. Providers may consider the administration of IV midazolam as part of a multimodal approach in preventing PONV.


Morphine vs. Dilaudid

The age old debate… about nausea, side effects, and analgesia… turns out they are closer than thought:

Meta-analysis of eight studies suggested that hydromorphone (494 patients) provides slightly better (P=0.012) clinical analgesia than morphine (510 patients). The effect-size was small (Cohen’s d=0.266) and disappeared when one study was removed, although the advantage of hydromorphone was more evident in studies of better quality (Jadad’s rating). Side-effects were similar, for example, nausea (P=0.383, nine studies, 456 patients receiving hydromorphone and 460 morphine); vomiting (P=0.306, six studies, 246 patients receiving hydromorphone and 239 morphine); or itching (P=0.249, eight studies, 405 patients receiving hydromorphone, 410 morphine). This suggests some advantage of hydromorphone over morphine for analgesia. Additional potential clinical pharmacological advantages with regard to side-effects, such as safety in renal failure or during acute analgesia titration, are based on limited evidence and require substantiation by further studies.

From Feldan et al. BJA 2011. http://bja.oxfordjournals.org/content/107/3/319.full


Lactated Ringer’s: All Good, All the time

Great post from emcrit.org on the myths of using LR in renal failure, specifically pointing out the physiology then backing it up with clinical trials:

the primary reason that this myth is wrong has to do with potassium shifting between the cells and the extracellular fluid.   About 98% of the potassium in the body is present inside the cells, with an intracellular potassium concentration of ~140 mEq/L.   Therefore, even a tiny shift of potassium out of the cellular compartment will have a major effect on extracellular potassium levels.   NS causes a non-anion gap metabolic acidosis, which shifts potassium out of cells, thereby increasing the potassium level.   On the other hand, LR does not cause an acidosis, but instead may have a mild alkalinizing effect given that it contains the equivalent of 28 mEq/L of bicarbonate.   Potassium shifts have a greater effect on the serum potassium than the actual concentration of potassium in the infused solution.

The trials were quite excellent, with one comparing LR vs NS use in patients undergoing renal transplant.. the trial was actually stopped early as the LR patients were doing so much better than the NS patients:


They performed a prospective, randomized, double-blind controlled trial of NS versus LR among 52 patients undergoing renal transplant surgery.   The mean change in serum potassium during the procedure was +0.5 mEq/L in the NS group compared to -0.5 mEq/L in the LR group (p < 0.001; figure below).   Patients in the NS group also had lower pH levels following surgery.     


More detailed explanation at EMCRIT ( http://emcrit.org/pulmcrit/myth-busting-lactated-ringers-is-safe-in-hyperkalemia-and-is-superior-to-ns/ )


Another common myth associated with LR has to do with blood transfusions, according to this the calcium in LR can cause clots by overwhelming the chelating capability of the citrate in stored blood. But as a trial from 1998 demonstrated, this is also false and blood banks should recommend using LR for its advantages during trauma resuscitation vs. NS.  See: http://www.aafp.org/afp/1998/0801/p502.html

So next time someone tells you to use NS for whatever reason in the OR or elsewhere, let them know LR is the best!