Evaluation of paradoxical effect of small dose ketamine as adjuvant in deep sedation for endoscopy patients

ABSTRACT

Background

This study tested the hypothesis that use of ketamine as an ‎adjuvant to propofol in the induction of deep sedation for ‎endoscopy patients could lead, paradoxically, to faster ‎emergence.‎

Methods

We conducted a single-center, prospective randomized ‎controlled study on 154 adult ASA I or II patients‎, admitted for ‎gastrointestinal endoscopies‎. Patients were sedated with 25 µg ‎fentanyl and 1 mg/kg propofol bolus over 30 s. Patients ‎were divided into two groups: Group P (n = 77), sedated with ‎propofol only, and Group PK (n = 77), who received additionally a ‎single dose of ketamine (0.1 mg/kg) at induction. If the patient ‎moved or Ramsay Sedation Score (RSS) regressed to <4, ‎increments of 0.25 mg/kg of propofol were given. After the end ‎of the procedure, emergence from sedation was assessed with ‎modified Aldrete score, 5 and 10 m after admission to the ‎recovery room.‎

Results

Adding a small dose of ketamine did not significantly achieve ‎deep sedation (RSS ≥4) more quickly or result in lesser ‎propofol increments. Patients who received ketamine showed a ‎statistically significant improvement in the Modified Aldrete ‎score when recorded 5 min after admission to the recovery ‎room (Group P 8.73 ± 1.02, Group PK 9.1 ± 0.96, P value = ‎‎0.02), but not after 10 min (Group P 9.03 ± 0.74, Group PK ‎‎9.21 ± 0.8, P value = 0.146).‎

Conclusion

Inclusion of a small single dose of ketamine in the induction of sedation for gastrointestinal endoscopy significantly improves emergence from sedation.

KEYWORDS:

• Propofol sedation
• ketamine paradoxical effect
• gastrointestinal endoscopy

Ethics approval and consent to participate

Approval for this study was obtained from the Research Ethical Committee of Faculty of Medicine, Ain Shams University (code number: FMASU R 108/2022), and written informed consent was obtained from patients. The study was also registered in the Pan African Clinical Trials Registry (identification number: PACTR202208588389635).

Acknowledgments

This study is directly inspired by the Hambrecht-Wiedbusch et al. study published in 2017, exploring the role of a subanesthetic dose of ketamine in isoflurane anesthesia in rats. The researchers would like to thank all patients that participated in the study and their families. Furthermore, the researchers would like to acknowledge the contributions of the members of the anesthesia team, as well as of the surgical and internal medicine staff in the Gastrointestinal Endoscopy Unit, Ain Shams University Hospitals, Cairo, Egypt.

Disclosure statement

The researcher declares no competing interests.

Additional information

Funding

The authors certify that except for local institutional resources, they received no ‎fund for this research from any source.‎