Effects of Ketamine Infusion on Breathing and Encephalography in Spontaneously Breathing ICU Patients

Aiman Suleiman, Peter Santer, Ronny Munoz-Acuna, Maximilian Hammer, Maximilian S. Schaefer, Luca J. Wachtendorf, Sandra Rumyantsev, Lorenzo Berra, Shubham Chamadia, Oluwaseun Johnson-Akeju, Elias N. Baedorf-Kassis, Matthias Eikermann

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Background: Preclinical studies suggest that ketamine stimulates breathing. We investigated whether adding a ketamine infusion at low and high doses to propofol sedation improves inspiratory flow and enhances sedation in spontaneously breathing critically ill patients. Methods: In this prospective interventional study, twelve intubated, spontaneously breathing patients received ketamine infusions at 5 mcg/kg/min, followed by 10 mcg/kg/min for 1 h each. Airway flow, pressure, and esophageal pressure were recorded during a spontaneous breathing trial (SBT) at baseline, and during the SBT conducted at the end of each ketamine infusion regimen. SBT consisted of one-minute breathing with zero end-expiratory pressure and no pressure support. Changes in inspiratory flow at the pre-specified time points were assessed as the primary outcome. Ketamine-induced change in beta-gamma electroencephalogram power was the key secondary endpoint. We also analyzed changes in other ventilatory parameters respiratory timing, and resistive and elastic inspiratory work of breathing. Results: Ketamine infusion of 5 and 10 mcg/kg/min increased inspiratory flow (median, IQR) from 0.36 (0.29-0.46) L/s at baseline to 0.47 (0.32-0.57) L/s and 0.44 (0.33-0.58) L/s, respectively (p =.013). Resistive work of breathing decreased from 0.4 (0.1-0.6) J/l at baseline to 0.2 (0.1-0.3) J/l after ketamine 10 mcg/kg/min (p =.042), while elastic work of breathing remained unchanged. Electroencephalogram beta-gamma power (19-44 Hz) increased compared to baseline (p <.01). Conclusions: In intubated, spontaneously breathing patients receiving a constant rate of propofol, ketamine increased inspiratory flow, reduced inspiratory work of breathing, and was associated with an “activated” electroencephalographic pattern. These characteristics might facilitate weaning from mechanical ventilation.

Original languageEnglish (US)
Pages (from-to)299-306
Number of pages8
JournalJournal of Intensive Care Medicine
Issue number3
StatePublished - Mar 2023


  • ICU sedation
  • Ketamine infusion
  • brain activity
  • critical care ventilation
  • inspiratory flow
  • mechanical ventilation
  • spontaneous breathing trial
  • weaning from ventilator

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


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