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Mechanical VentilationNCT01969227

The Effects of Ketamine on Respiratory Stimulation and Transpulmonary Pressures

A study testing Subanesthetic ketamine in people with Mechanical Ventilation and Airway Patency, run by Massachusetts General Hospital at 2 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

Impairment of airway patency is a common cause of extubation failure and opioids and hypnotics can adversely affect airway patency. Ketamine, a noncompetitive antagonist of N-methyl-D-aspartate (NMDA), unlike other anesthetics activates respiratory effort and promotes bronchodilation. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Subanesthetic ketamine
Type of treatment
Injection or infusion
Could I receive a placebo?
No, everyone receives an active treatment
How many people
15 participants
Where
2 sitesUnited States
Study dates
Jan 2014to Dec 2022
Phase
Interventional
Are there results?
Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Age ≥ 18 years admitted to ICU requiring mechanical ventilation
  • Suitable for spontaneous breathing trial
  • Candidate to received low dose ketamine by the primary critical care team

Who cannot join

  • Esophageal injury
  • Allergic to ketamine
  • Known neurodegenerative disorders
  • Major neurologic disorders (elevated ICP)

Trial locations and contacts

2 sites in 1 country.

United States2 sites
  • Massachusetts General Hospital

    Boston, Massachusetts, 02114

  • Beth Israel Deaconess Medical Center

    Boston, Massachusetts, 02215

Other trials in United States

About this study

Official title: The Effects of Subanesthetic Ketamine on Respiratory Stimulation and Transpulmonary Pressures in Mechanically Ventilated Critically Ill Patients

Impairment of airway patency is a common cause of extubation failure and opioids and hypnotics can adversely affect airway patency. Ketamine, a noncompetitive antagonist of N-methyl-D-aspartate (NMDA), unlike other anesthetics activates respiratory effort and promotes bronchodilation. At subanesthetic plasma concentration, ketamine reduces both opioid and propofol requirements.

The purpose of this pharmaco-physiological interaction trial is to evaluate the effects of ketamine on breathing and electroencephalography in mechanically ventilated patients.

Read the detailed description

Maintaining the patency of the upper airway in sedated and anesthetized patients is challenging especially when patients are ready to be weaned from mechanical ventilation. Spontaneous breathing trial (SBT) is used to expedite the weaning process, which oftentimes requires the reduction and/or discontinuation of sedatives and analgesics. In some surgical patients, reducing these medications can lead to pain associated agitation and inability to conduct SBTs, which may prolong the need for mechanical ventilation. Using medications with narcotic sparing effects and that do not cause respiratory depression may allow for the reduction or discontinuation of agents that depress respiratory drive and subsequently facilitate extubation.

Ketamine has been used for many years in critically ill patients for sedation and analgesia. This noncompetitive antagonist of N-methyl-D-aspartate (NMDA) is used as an anesthetic and analgesic and has been shown to reduce opioid consumption and to prevent the development of opioid tolerance. Unlike other anesthetics, ketamine activates respiratory effort and promotes bronchodilation. At subanesthetic plasma concentration, ketamine reduces both opioid and propofol requirements.

The goal of this pharmaco-physiological interaction trial is to evaluate the effects of ketamine at a subanesthetic dose on breathing and electroencephalography. The investigators hypothesize that ketamine drip at a subanesthetic infusion rate (low dose ketamine 5 - 10 mcg/kg/min) is associated with respiratory stimulating effects and does not markedly increase transpulmonary pressure in mechanically ventilated patients.

The primary outcome is respiratory function, assessed through peak inspiratory flow, tidal volume,respiratory rate, duty cycle, and minute ventilation measured 15 minutes prior to initiation of ketamine infusion (to serve as baseline), at 60 minutes of ketamine infusion at 5mcg/kg/min, at another 60 minutes of infusion at 10mcg/kg/min, at which point the infusion is stopped for 3 hours for a final set of measurements.

Being tested
Subanesthetic ketamine
Keywords
Subanesthetic ketamine, Mechanical ventilation, Transpulmonary pressure, Spontaneous breathing trial, Extubation
Medical subject headings
Respiratory Insufficiency

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Subanesthetic ketamineDrug

    Ketamine drip at a subanesthetic infusion rate (low dose ketamine 5 - 10 mcg/kg/min)

Study groups in NCT01969227
Study groupRoleWhat they receive
CohortExperimentalAdult mechanically ventilated patients who are deemed eligible for a spontaneous breathing trial and are candidates to receive subanesthetic ketamine by the primary critical care team.
Receives: Drug: Subanesthetic ketamine

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Inspiratory Airflow

    Inspiratory airflow measured during spontaneous breathing trials without ventilator support using a calibrated pneumotachometer connected to the ventilatory circuit. Airflow signals were recorded along with airway and esophageal pressures and analyzed. Inspiratory airflow represents the rate of air entering the lungs during inspiration and is reported in liters per second (L/s). Higher values indicate greater inspiratory airflow during spontaneous breathing. Measurements were obtained during brief spontaneous breathing trials performed at predefined study time points.

    Measured: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min

Secondary outcomes (6)
  1. EEG Beta-gamma Power

    Electroencephalogram (EEG) power spectrum density was measured using four frontal electrodes with the SedLine monitor and analyzed using multitaper spectral methods. Changes in beta-gamma power (19-44 Hz) were expressed in decibels (dB) relative to baseline using artifact-free ~3-minute segments at predefined time points. The reported value represents the maximum increase in spectral power across the frequency range, capturing the strongest frequency-specific effect, which may be diluted by averaging across the band if central tendency is used. This approach is standard in spectral analyses to detect peak effects and potential frequency shifts. Power spectra are continuous functions and peak values are the dominant signal components because they represent the strongest oscillatory activity the brain could achieve in a predefined frequency range.

    Measured: Baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min.

  2. Minute Ventilation

    Minute ventilation measured during spontaneous breathing trials without ventilator support using a calibrated pneumotachometer connected to the ventilatory circuit. Minute ventilation represents the total volume of air inhaled or exhaled per minute and is calculated as tidal volume multiplied by respiratory rate. Values are reported in liters per minute (L/min). Higher values indicate greater overall ventilation during spontaneous breathing. Measurements were derived from airflow recordings.

    Measured: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min.

  3. Tidal Volume

    Tidal volume measured during spontaneous breathing trials without ventilator support using a calibrated pneumotachometer connected to the ventilatory circuit. Tidal volume represents the volume that enters the lungs during a single breath and is reported in liters (L). Values were derived from airflow recordings analyzed using spirometry software. Higher values indicate larger breath volumes during spontaneous breathing at the predefined study time points.

    Measured: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min.

  4. Work of Breathing

    Inspiratory work of breathing measured during spontaneous breathing trials using esophageal pressure (Pes) and tidal volume recordings. Work of breathing was calculated from the area under the inspiratory limb of the esophageal pressure-volume loop for each breathing cycle. Values were averaged across breaths during the recording period and normalized to tidal volume. Work of breathing was expressed in joules per liter (J/L). Higher values indicate greater mechanical effort required to inhale.

    Measured: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min.

  5. Inspiratory Airway Resistance

    Inspiratory airway resistance measured during spontaneous breathing trials using airway flow and esophageal pressure recordings. Resistance was estimated using the Mead and Whittenberger method, calculated as (Pes - PesLR)/V̇, where Pes is esophageal pressure, PesLR is the pressure on the lung elastic recoil curve at the same tidal volume, and V̇ is airflow. Measurements were made at an absolute tidal volume of 100 ml and averaged across breathing cycles during the recording period. Values are reported in cmH2O/L/s. Higher values indicate greater resistance to airflow during inspiration.

    Measured: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min.

  6. Lung Compliance

    Lung compliance measured during spontaneous breathing trials using tidal volume and esophageal pressure recordings. Compliance was calculated as the change in tidal volume divided by the change in esophageal pressure (ΔVT/ΔPes) measured between zero-flow states at the beginning and end of inspiration. Values represent respiratory system compliance and are reported in milliliters per centimeter of water pressure (mL/cmH2O). Higher values indicate greater lung compliance, reflecting a larger volume change for a given pressure change.

    Measured: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min.

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted25 Oct 2013 (estimated)
  2. Study startJan 2014
  3. Primary completionDec 2022
  4. Study completionDec 2022

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
15 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT01969227
Sponsor's protocol ID
2013P001690
Status last verified
Apr 2026
First submitted
8 Oct 2013
Last updated
19 May 2026
Data monitoring committee
No

Publications

  • Eikermann M, Grosse-Sundrup M, Zaremba S, Henry ME, Bittner EA, Hoffmann U, Chamberlin NL. Ketamine activates breathing and abolishes the coupling between loss of consciousness and upper airway dilator muscle dysfunction. Anesthesiology. 2012 Jan;116(1):35-46. doi: 10.1097/ALN.0b013e31823d010a.

    PubMed 22108392
  • Esteban A, Frutos F, Tobin MJ, Alia I, Solsona JF, Valverdu I, Fernandez R, de la Cal MA, Benito S, Tomas R, et al. A comparison of four methods of weaning patients from mechanical ventilation. Spanish Lung Failure Collaborative Group. N Engl J Med. 1995 Feb 9;332(6):345-50. doi: 10.1056/NEJM199502093320601.

    PubMed 7823995
  • Menigaux C, Fletcher D, Dupont X, Guignard B, Guirimand F, Chauvin M. The benefits of intraoperative small-dose ketamine on postoperative pain after anterior cruciate ligament repair. Anesth Analg. 2000 Jan;90(1):129-35. doi: 10.1097/00000539-200001000-00029.

    PubMed 10624993
  • Hirota K, Hashimoto Y, Sakai T, Sato T, Ishihara H, Matsuki A. In vivo spasmolytic effect of ketamine and adrenaline on histamine-induced airway constriction. Direct visualization method with a superfine fibreoptic bronchoscope. Acta Anaesthesiol Scand. 1998 Feb;42(2):184-8. doi: 10.1111/j.1399-6576.1998.tb05106.x.

    PubMed 9509200
  • Morel DR, Forster A, Gemperle M. Noninvasive evaluation of breathing pattern and thoraco-abdominal motion following the infusion of ketamine or droperidol in humans. Anesthesiology. 1986 Oct;65(4):392-8. doi: 10.1097/00000542-198610000-00008.

    PubMed 3767037
  • Kissin I, Bright CA, Bradley EL Jr. The effect of ketamine on opioid-induced acute tolerance: can it explain reduction of opioid consumption with ketamine-opioid analgesic combinations? Anesth Analg. 2000 Dec;91(6):1483-8. doi: 10.1097/00000539-200012000-00035.

    PubMed 11094005

Questions about this trial

What is this clinical trial studying?

A study testing Subanesthetic ketamine in people with Mechanical Ventilation and Airway Patency, run by Massachusetts General Hospital at 2 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 19 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

Yes. Results are posted in the registry (first posted 19 May 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Inspiratory Airflow (time frame: During spontaneous breathing trials at baseline (prior to ketamine infusion), after 60 minutes of ketamine infusion at 5 mcg/kg/min, and after 60 minutes of ketamine infusion at 10 mcg/kg/min). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT01969227, which also lists 6 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 May 2026.

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