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| Name | Class |
|---|---|
| Beth Israel Deaconess Medical Center | OTHER |
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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Cohort | Experimental | Adult 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. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Subanesthetic ketamine | Drug | Ketamine drip at a subanesthetic infusion rate (low dose ketamine 5 - 10 mcg/kg/min) |
|
| Measure | Description | Time Frame |
|---|---|---|
| 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. | 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 |
| Measure | Description | Time Frame |
|---|---|---|
| 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. |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Lorenzo Berra, MD | Massachusetts General Hospital | Principal Investigator |
| Matthias Eikermann, MD, PhD | Beth Israel Deaconess Medical Center | Study Director |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Massachusetts General Hospital | Boston | Massachusetts | 02114 | United States | ||
| Beth Israel Deaconess Medical Center |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 22108392 | Background | 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. | |
| 7823995 | Background |
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No specific pre-assignment run-in or washout period occurred. After enrollment and confirmation of eligibility, participants proceeded directly to the study intervention and measurements according to the protocol.
Participants were recruited in the surgical ICUs of two Boston academic medical centers (Massachusetts General Hospital and Beth Israel Deaconess Medical Center). Study personnel screened ICU censuses daily (7:30am-10:00pm) and through clinician referral. Eligible intubated adults suitable for SBT and on stable sedation ≥3 hours were approached via a clinician, with surrogate written consent obtained.
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| ID | Title | Description |
|---|---|---|
| FG000 | Ketamine Infusion (5 Then 10 mcg/kg/Min) During Propofol Sedation | Participants received a continuous infusion of ketamine at 5 mcg/kg/min for 1 hour followed by 10 mcg/kg/min for another hour while maintained on a constant propofol sedation rate. Spontaneous breathing trials (SBT) with zero end-expiratory pressure and no pressure support were performed for 1 minute at baseline (before ketamine), after 1 hour of low-dose ketamine, and after 1 hour of high-dose ketamine. During these trials, inspiratory flow, tidal volume, minute ventilation, respiratory rate, esophageal pressure, and work of breathing were measured. Continuous EEG monitoring was performed throughout the study period. After 2 hours, ketamine infusion was discontinued and routine ICU care continued. |
| Title | Milestones | Reasons Not Completed | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
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Fifteen participants were enrolled. Three were excluded from analysis due to events during the study period that prevented completion of study measurements (administration of fentanyl causing apnea in one participant and ICU interventions limiting data acquisition in two participants). Baseline characteristics are therefore reported for the 12 participants who completed the study measurements.
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| ID | Title | Description |
|---|---|---|
| BG000 | Ketamine Infusion (5 Then 10 mcg/kg/Min) During Propofol Sedation | Participants received a continuous ketamine infusion of 5 mcg/kg/min for 1 hour followed by 10 mcg/kg/min for another hour while maintained on a constant propofol sedation infusion. Spontaneous breathing trials with PEEP 0 and no pressure support were performed at baseline, after 1 hour of low-dose ketamine, and after 1 hour of high-dose ketamine. Respiratory variables, work of breathing, esophageal pressure, and EEG activity were recorded during these trials. |
| Units | Counts |
|---|---|
| Participants |
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| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Age of participants at the time of study enrollment, reported in years. Values represent the chronological age of adult ICU patients included in the study |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | 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. | The analysis population included the 12 participants who completed the study measurements. Three enrolled participants were excluded from analysis because study measurements could not be completed due to clinical events during the study period. | Posted | Median | Inter-Quartile Range | L/s | 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 |
|
From initiation of ketamine infusion until 3 hours after discontinuation of the 2-hour ketamine infusion (5 hours from starting ketamine)
Adverse events were monitored in all participants during ketamine infusion and for 3 hours after discontinuation of the infusion. Events were identified through continuous clinical monitoring and review of hemodynamic parameters by the study team as part of ICU care. The analysis population included the 12 participants who completed the study measurements. No adverse events were observed.
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Ketamine Infusion (5 Then 10 mcg/kg/Min) During Propofol Sedation | Participants received a continuous infusion of ketamine at 5 mcg/kg/min for 1 hour followed by 10 mcg/kg/min for another hour while maintained on a constant propofol sedation rate. Spontaneous breathing trials (SBT) with zero end-expiratory pressure and no pressure support were performed for 1 minute at baseline (before ketamine), after 1 hour of low-dose ketamine, and after 1 hour of high-dose ketamine. During these trials, inspiratory flow, tidal volume, minute ventilation, respiratory rate, esophageal pressure, and work of breathing were measured. Continuous EEG monitoring was performed throughout the study period. After 2 hours, ketamine infusion was discontinued and routine ICU care continued. |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Lorenzo Berra, MD | Massachusetts General Hospital | 617-726-3030 | lberra@mgh.harvard.edu |
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot_SAP | Yes | Yes | No | Study Protocol and Statistical Analysis Plan | Aug 8, 2022 | Mar 16, 2026 | Prot_SAP_000.pdf |
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| ID | Term |
|---|---|
| D012131 | Respiratory Insufficiency |
| ID | Term |
|---|---|
| D012120 | Respiration Disorders |
| D012140 | Respiratory Tract Diseases |
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| 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. |
| 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. | 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. |
| 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. | 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. |
| 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. | 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. |
| 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. | 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. |
| 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. | 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. |
| Boston |
| Massachusetts |
| 02215 |
| United States |
| 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. |
| 10624993 | Background | 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. |
| 9509200 | Background | 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. |
| 3767037 | Background | 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. |
| 11094005 | Background | 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. |
| Mean |
| Standard Deviation |
| years |
|
| Sex: Female, Male | Sex of participants recorded at study enrollment based on the medical record. Participants were categorized as female or male. Values represent the number of participants in each category. | Sex was reported for all participants included in the analysis population. No participants were excluded from this baseline measure. | Count of Participants | Participants |
|
| Race and Ethnicity Not Collected | Race and Ethnicity were not collected from any participant. | Count of Participants | Participants |
|
| Body Mass Index (BMI) | Body Mass Index (BMI) calculated as body weight in kilograms divided by height in meters squared (kg/m^2). BMI provides an estimate of body fat based on weight and height and is commonly used to classify body size in adults. Higher values indicate greater body mass relative to height. | BMI was reported for all participants included in the analysis population. No participants were excluded from this baseline measure analysis. | Median | Inter-Quartile Range | kg/m^2 |
|
| APACHE II (Acute Physiology and Chronic Health Evaluation II) score | Acute Physiology and Chronic Health Evaluation II (APACHE II) score, a validated severity-of-illness scoring system used in intensive care units to estimate disease severity and risk of mortality. The score ranges from 0 to 71, calculated from physiologic measurements, age, and chronic health status during the first 24 hours of ICU admission. Higher scores indicate more severe illness and higher predicted mortality risk. | APACHE II was reported for all participants included in the analysis population. No participants were excluded from this baseline measure analysis. | Median | Inter-Quartile Range | points |
|
| SOFA (Sequential Organ Failure Assessment) score | Sequential Organ Failure Assessment (SOFA) score, a validated scoring system used in intensive care units to assess the extent of organ dysfunction. The total score ranges from 0 to 24, calculated from six organ systems (respiratory, cardiovascular, hepatic, coagulation, renal, and neurologic), each scored from 0 to 4. Higher scores indicate greater organ dysfunction and increased severity of illness. | Median | Inter-Quartile Range | points |
|
| RASS (Richmond Agitation-Sedation Scale) at study start | Richmond Agitation-Sedation Scale (RASS), a validated clinical scale used in intensive care units to assess the level of agitation or sedation. The scale ranges from -5 to +4, where -5 indicates unarousable sedation, 0 indicates alert and calm, and +4 indicates combative agitation. Lower scores represent deeper sedation, while higher positive scores indicate increasing agitation. | Median | Inter-Quartile Range | score |
|
| Primary ICU admission diagnosis / reason for mechanical ventilation | Primary clinical reason for admission to the intensive care unit and for the need for mechanical ventilation at the time of study enrollment, as documented in the medical record. Participants were categorized according to the primary diagnosis prompting ICU admission and ventilatory support. Values represent the number of participants in each diagnostic category. | Count of Participants | Participants |
|
| History of pulmonary disease | History of pulmonary disease recorded from the medical record at the time of study enrollment. Pulmonary disease includes documented chronic respiratory conditions such as chronic obstructive pulmonary disease (COPD), asthma, or other chronic lung disorders diagnosed prior to ICU admission. Values represent the number of participants with a history of pulmonary disease. | Count of Participants | Participants |
|
| OG000 |
| Ketamine Infusion (5 Then 10 mcg/kg/Min) During Propofol Sedation |
Participants received a continuous infusion of ketamine at 5 mcg/kg/min for 1 hour followed by 10 mcg/kg/min for another hour while maintained on a constant propofol sedation rate. Spontaneous breathing trials (SBT) with zero end-expiratory pressure and no pressure support were performed for 1 minute at baseline (before ketamine), after 1 hour of low-dose ketamine, and after 1 hour of high-dose ketamine. During these trials, inspiratory flow, tidal volume, minute ventilation, respiratory rate, esophageal pressure, and work of breathing were measured. Continuous EEG monitoring was performed throughout the study period. After 2 hours, ketamine infusion was discontinued and routine ICU care continued. |
|
|
| Secondary | 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. | The analysis population included the 12 participants who completed the study measurements and had analyzable EEG recordings. | Posted | Number | dB | 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. |
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| Secondary | 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. | The analysis population included the 12 participants who completed the study measurements. No additional exclusions were made for this outcome. | Posted | Median | Inter-Quartile Range | L/min | 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. |
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|
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| Secondary | 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. | The analysis population included the 12 participants who completed the study measurements. No additional exclusions were made for this outcome. | Posted | Median | Inter-Quartile Range | L | 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. |
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| Secondary | 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. | The analysis population included the 12 participants who completed the study measurements. No additional exclusions were made for this outcome. | Posted | Median | Inter-Quartile Range | J/L | 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. |
|
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|
| Secondary | 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. | The analysis population included the 12 participants who completed the study measurements. No additional exclusions were made for this outcome. | Posted | Median | Inter-Quartile Range | cmH2O/L/s | 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. |
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| Secondary | 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. | The analysis population included the 12 participants who completed the study measurements. No additional exclusions were made for this outcome. | Posted | Median | Inter-Quartile Range | mL/cmH2O | 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. |
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| 0 |
| 12 |
| 0 |
| 12 |
| 0 |
| 12 |
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