Prevention of Fentanyl Induced Cough by Ketorolac: A Prospective, Randomized, and Double-Blind Study

Fentanyl is often used during general anesthesia and can cause reflex cough.

We assessed the effectiveness of administering intravenous ketorolac in reducing the incidence and severity of cough caused by fentanyl, aiming to find an alternative to lidocaine in cases where it is contraindicated.

In a prospective randomized controlled trial, a total of 210 patients, classified as American Society of Anesthesiologists (ASA) I or II, undergoing elective surgery, were randomly allocated to three groups: The Ketorolac group (K), the Lidocaine group (L), and the normal saline group (N). Three minutes before the injection of 3 mcg/kg intravenous fentanyl, patients received 0.5 mg/kg ketorolac, 1 mg/kg lidocaine, and 2 cc of 0.9% normal saline, respectively. The onset and severity of cough were documented within 3 minutes after the administration of fentanyl.

There was a significant difference in the onset time of cough between the groups (P = 0.001). Three individuals (4.3%) in group L and nine individuals (12.9%) in group N experienced severe coughs, with a significant difference in cough intensity among the groups (P = 0.001). There was no significant difference in heart rate (HR) and arterial oxygen saturation (SpO₂) at different time points (P > 0.05) among the three groups. However, there was a significant difference among the groups regarding arterial blood pressure (BP) 3 minutes after fentanyl injection and 1 minute after intubation (P = 0.003, 0.001, respectively), with the mean arterial BP being higher in group N than in group L, and higher in group L than in group K.

The administration of ketorolac and lidocaine decreases both the frequency and severity of cough induced by fentanyl, especially in individuals who received ketorolac, as no cases of severe cough were observed. Therefore, ketorolac can be used in cases where lidocaine is contraindicated to prevent coughing due to fentanyl.