Background: Non-pharmacological techniques aimed at reducing adverse reactions from ketamine have not been investigated for ED patients. We conducted an ED-based pilot study to evaluate the association between the power of positive suggestion/thoughts and the severity of emergence reactions after procedural sedation with ketamine.
Methods: We enrolled a convenience sample of consenting, inner-city ED patients undergoing procedural sedation in a randomized, controlled trial. Subjects rated initial anxiety/agitation on a previously validated instrument (STAI: Y-6) and a 10-point VAS. Control group read a standardized script describing the potential adverse effects of ketamine. Intervention group asked to focus on a positive dream and verbalize that dream to the caregiver pre-sedation. Ketamine 1.5 mg/kg administered at a rate of 0.5mg/kg/min. Post-procedure, patients were asked about dream occurrence and to rate character on a 1-5 scale. Categorical data analyzed by Fisher Exact test and Chi-square; continuous data by t-tests. Mean VAS anxiety score changes were analyzed by Wilcoxon Rank Sum test with each subject serving as their own control.
Results: 28 patients enrolled; 14 intervention, 39% female, 40% < 50 years age. The two groups (control vs. intervention) were similar with respect to female gender (36% vs.43%; p=0.70; OR 1.35; 95% CI 0.29-6.18), age group (p= 0.64), income group (p=0.27), education level (p=0.15), Hispanic race (p=1.0; OR 1; 95% CI 0.22-4.46),and length of sedation 24+/-10 vs. 23+/-13 min (p=0.92). STAY: Y-6 scores pre-sedation were similar for both groups 53.1+/-7.6 vs. 52.0+/-13.3 (p=0.80) but the pre-sedation mean anxiety VAS were different (5.3+/-2.1 vs. 3.3+/-1.8; p=0.02). Dreams were less frequent (64% vs. 91%; p=0.18) and were less often rated for pleasantness > or = 3 (36% vs. 64%; p=0.20; OR= 0.33, 95% CI 0.06-1.9) in the control group, but these differences were not statistically significant. The incidence of adverse events (33% vs. 46%; p=0.51; OR 1.7; 95% CI (0.34-8.7), post-sedation mean VAS 2.5+/-1.78 vs. 1.14+/-1.21 (p=0.11), and mean difference in change in VAS -2.83+/-1.19 vs. -1.71+/-1.70 (p=0.15) were similar.
Conclusions: For our intervention group, pleasant dreams occurred more frequently and there were lower post-sedation anxiety scores, but these differences and those observed for other outcome measures were not statistically significant. As investigators in other settings have reported reduced emergence reactions in association with non-pharmacological preventative measures, we believe larger ED-based studies are warranted.