Respuesta hemodinámica a dosis subanestésicas de ketamina en dolor posoperatorio: revisión sistemática

Introduction: Low-dose ketamine infusions have shown analgesic effectiveness for the management of postoperative pain. The impact of low-dose ketamine infusions on cardiovascular response is dose-dependent and requires a better knowledge about its effects on this population. Objective: To conduct a systematic review to describe changes in systolic, diastolic and mean arterial pressure, and heart rate 24, 48 and 72 hours after surgery. Methods: Randomized, controlled trials were reviewed in the  Cochrane Library, PubMed, EMBASE, SciELO, Lilacs and grey literature on low-dose ketamine infusions for the study variables. The quality of the studies was assessed using the Cochrane’s risk of bias tool. Results: Six randomized, controlled trials with 641 patients were included. Low-quality evidence was found suggestive of a lack of certainty of any significant differences in the systolic blood pressure variables at 24 hours (mean standard deviation  -1.00, 95 % CI: -7.27 to 5.27). A statistically significant higher mean heart rate at 24 hours was identified in the low-dose ketamine infusion group, (mean standard deviation 1.64 95 % CI: 0.38 to 2.90) which did not reach clinical significance. A lower pain level and less use of opioids was identified in the low-dose ketamine infusion group. Conclusion: Low quality evidence was found, suggesting that low-dose ketamine infusions are not associated with significant changes in blood pressure or heart rate 24 – 48 hours after surgery. It is important to individualize cardiovascular risk for each case, before initiating treatment.