Abstract
OBJECTIVES: There has been controversy over whether ketamine affects intracranial pressure (ICP) in children. Transcranial Doppler ultrasound (TCD) is a validated technique used to assess ICP changes noninvasively. Gosling pulsatility index (PI) directly correlates with ICP changes. The objective of this study was to quantify PI changes as a surrogate marker for ICP changes in previously healthy children receiving intravenous ketamine for procedural sedation. METHODS: We performed a prospective, observational study of patients 5-18 years old who underwent sedation with intravenous ketamine as monotherapy. ICP changes were assessed by surrogate PI at baseline, immediately after ketamine administration, and every 5 minutes until completion of the procedure. The primary outcome measure was PI change after ketamine administration compared to baseline (denoted ΔPI). RESULTS: We enrolled 15 participants. Mean age was 9.9 ± 3.4 years. Most participants underwent sedation for fracture reduction (87%). Mean initial ketamine dose was 1.4 ± 0.3 mg/kg. PI decreased at all time points after ketamine administration. Mean ΔPI at sedation onset was -0.23 (95% confidence interval [CI] = -0.30 to -0.15), at 5 minutes was -0.23 (95% CI = -0.28 to -0.18), at 10 minutes was -0.14 (95% CI = -0.21 to -0.08), at 15 minutes was -0.18 (95% CI = -0.25 to -0.12), and at 20 minutes was -0.19 (95% CI = -0.26 to -0.12). Using a clinically relevant threshold of ΔPI set at +1 (+8 cm H(2)O), no elevation in ICP, based on the PI surrogate marker, was demonstrated with 95% confidence at all time points after ketamine administration. CONCLUSIONS: Ketamine did not significantly increase PI, which was used as a surrogate marker for ICP in this sample of previously healthy children. This pilot study demonstrates a model for evaluating ICP changes noninvasively in the emergency department.