Respiration DisordersNCT00750074
Slope of the Pressure-Time Waveform Predicts Resistance and Compliance in Mechanically Ventilated Subjects
An observational study of Respiration Disorders, run by Gregory A. Schmidt at 1 site in United States.
Trial summary
There are two fundamentally different ways to ventilate critically ill patients: constant flow, volume-preset modes (such as volume assist-control) and pressure-preset modes (such as pressure-control and pressure-support). Read more about this study
- Who is it for?
- Ages 18 to 99 years
- Conditions the study is for
- Respiration Disorders
- How many people
- 12 participants
- Where
- 1 siteUnited States
- Study dates
- Nov 2007to Oct 2010
- Phase
- Observational
- Are there results?
- None posted in the registry
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 to 99 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Inclusion Criteria Subjects may be included in the study if they meet the following inclusion criterion and no exclusion criteria: [1] Adult medical or surgical ICU patients who are mechanically ventilated. Using a random number generator each subject will be assigned to pressure control or volume control for initial set of measurements.
Who may be able to join
- Subjects may be included in the study if they meet the following inclusion criterion and no exclusion criteria:
- Adult medical or surgical ICU patients who are mechanically ventilated.
Who cannot join
- Subjects with planned extubation at time of screening
- Subjects who are judged too hemodynamically unstable by their attending physician to participate in the study
- Subjects on high-frequency ventilation
- Subjects whose oxyhemoglobin saturation cannot be maintained at 88% or greater
- Subjects with large air leaks around the endotracheal or tracheostomy tube
- Subjects younger than 18 years old
- Inability to obtain informed consent from the subject or the subject's authorized representative
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Slope of the Pressure-Time Waveform Predicts Respiratory System Resistance and Elastance in Mechanically Ventilated Subjects
There are two fundamentally different ways to ventilate critically ill patients: constant flow, volume-preset modes (such as volume assist-control) and pressure-preset modes (such as pressure-control and pressure-support). Critically ill patients suffer mechanical derangements of the respiratory system that raise the work of breathing. Knowledge of these mechanical properties is useful diagnostically and as a measure of response to treatment over time. It has been proposed that only constant flow, volume-preset modes are able to offer diagnostic information about the changes in the subject's lungs in terms of resistance and elastance properties. This study proposes to examine if similar information can be extracted from pressure-preset modes by comparing information from both modes of ventilation.
Read the detailed description
Aim 1: To compare the respiratory system resistance and elastance obtained during constant-flow, volume-preset ventilation (using conventional means) and during pressure-preset ventilation (by analyzing the slope of the flow versus time waveform, as described below).
Aim 2: To determine whether patient effort and level of alertness impair the accuracy of resistance and elastance measurements during pressure-preset ventilation.
Hypothesis 1: Our primary hypothesis is that the flow versus time waveform contains information sufficient to calculate the respiratory system resistance and elastance. To test the primary hypothesis, we propose to measure resistance and elastance of subjects ventilated in the ICU during assist-control ventilation (a standard constant flow, volume-preset mode). Then we will record the flow versus time waveform during pressure-preset ventilation. By extrapolating the flow versus time waveform (which is generally linear) to the time axis, one can calculate elastance since at zero flow, the alveolar pressure equals the ventilator inspiratory pressure. Then Ers = (Pinsp - Total PEEP)/Extrapolated VT, where Pinsp is the set inspiratory pressure and extrapolated VT is the tidal volume if inspiratory time had been sufficient to allow equilibration between patient and ventilator (using trigonometry). Similarly, by extrapolating the flow versus time waveform to the flow axis (to find the maximal flow), one can calculate the resistance, assuming that flow depends on the pressure difference between ventilator and patient and the square of the resistance. We will compare the values derived during pressure-preset ventilation with those determined during assist-control (taken as the true values).
Hypothesis 2: We hypothesize that inspiratory effort will be sufficient in some subjects to distort the flow versus time waveform from that which would be seen if the patient were passive, leading to erroneous values for resistance and elastance. We will estimate the respiratory drive using a standard measure, the fall in Pao during a brief inspiratory occlusion 100ms following the onset of inspiration (P0.1). Further, we will measure each subject's alertness on the Richmond Agitation-Sedation Scale (RASS). We expect our estimations of resistance and elastance to less accurate (during pressure-preset ventilation compared with assist-control) in subjects with greater respiratory drive and higher levels of alertness.
- Conditions
- Respiration Disorders
- Keywords
- mechanical ventilation
- Medical subject headings
- Respiration Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| 1 | During volume assist-control ventilation, a 0.4 second end-inspiratory pause will be set and the following pressures measured: peak pressure; plateau pressure; and PEEP. The following ventilator settings will be recorded: inspiratory flow; expired tidal volume; and rate. The presence or absence of autoPEEP will be noted. During pressure-control ventilation, the flow versus time waveform will be printed from the ventilator using a conventional computer printer for later analysis. The following ventilator settings will be recorded: inspiratory pressure; PEEP; and expired tidal volume. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Outcome measure: resistance and compliance measured during pressure control versus volume control ventilation
Measured: duration of study
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Sep 2008 (estimated)
- Study startNov 2007
- Primary completionSep 2009
- Study completionOct 2010
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Respiration DisordersStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 12 participants (actual)
Sponsor and investigators
- Lead sponsor
- Gregory A. Schmidt
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Gregory A. Schmidt, University of Iowa
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00750074
- Sponsor's protocol ID
- 200608720
- Status last verified
- Feb 2017
- First submitted
- 9 Sep 2008
- Last updated
- 28 Feb 2017
- Results posted
- No
- Data monitoring committee
- No
Study at a glance
From the registry record, last updated by the sponsor on 28 Feb 2017. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Slope of the Pressure-Time Waveform Predicts Respiratory System Resistance and Elastance in Mechanically Ventilated Subjects
- ClinicalTrials.gov ID
- NCT00750074
- Acronym / sponsor ID
- 200608720
- Conditions
- Respiration Disorders
- Keywords
- mechanical ventilation
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 12 participants (actual)
- Lead sponsor
- Gregory A. SchmidtUniversity, hospital or other
- Study start
- Nov 2007
- Primary completion
- Sep 2009 (actual)
- Study completion
- Oct 2010 (actual)
- First posted
- 10 Sep 2008 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
There are two fundamentally different ways to ventilate critically ill patients: constant flow, volume-preset modes (such as volume assist-control) and pressure-preset modes (such as pressure-control and pressure-support). Critically ill patients suffer mechanical derangements of the respiratory system that raise the work of breathing. Knowledge of these mechanical properties is useful diagnostically and as a measure of response to treatment over time. It has been proposed that only constant flow, volume-preset modes are able to offer diagnostic information about the changes in the subject's lungs in terms of resistance and elastance properties. This study proposes to examine if similar information can be extracted from pressure-preset modes by comparing information from both modes of ventilation.
Detailed description
Aim 1: To compare the respiratory system resistance and elastance obtained during constant-flow, volume-preset ventilation (using conventional means) and during pressure-preset ventilation (by analyzing the slope of the flow versus time waveform, as described below).
Aim 2: To determine whether patient effort and level of alertness impair the accuracy of resistance and elastance measurements during pressure-preset ventilation.
Hypothesis 1: Our primary hypothesis is that the flow versus time waveform contains information sufficient to calculate the respiratory system resistance and elastance. To test the primary hypothesis, we propose to measure resistance and elastance of subjects ventilated in the ICU during assist-control ventilation (a standard constant flow, volume-preset mode). Then we will record the flow versus time waveform during pressure-preset ventilation. By extrapolating the flow versus time waveform (which is generally linear) to the time axis, one can calculate elastance since at zero flow, the alveolar pressure equals the ventilator inspiratory pressure. Then Ers = (Pinsp - Total PEEP)/Extrapolated VT, where Pinsp is the set inspiratory pressure and extrapolated VT is the tidal volume if inspiratory time had been sufficient to allow equilibration between patient and ventilator (using trigonometry). Similarly, by extrapolating the flow versus time waveform to the flow axis (to find the maximal flow), one can calculate the resistance, assuming that flow depends on the pressure difference between ventilator and patient and the square of the resistance. We will compare the values derived during pressure-preset ventilation with those determined during assist-control (taken as the true values).
Hypothesis 2: We hypothesize that inspiratory effort will be sufficient in some subjects to distort the flow versus time waveform from that which would be seen if the patient were passive, leading to erroneous values for resistance and elastance. We will estimate the respiratory drive using a standard measure, the fall in Pao during a brief inspiratory occlusion 100ms following the onset of inspiration (P0.1). Further, we will measure each subject's alertness on the Richmond Agitation-Sedation Scale (RASS). We expect our estimations of resistance and elastance to less accurate (during pressure-preset ventilation compared with assist-control) in subjects with greater respiratory drive and higher levels of alertness.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| 1 | – | –During volume assist-control ventilation, a 0.4 second end-inspiratory pause will be set and the following pressures measured: peak pressure; plateau pressure; and PEEP. The following ventilator settings will be recorded: inspiratory flow; expired tidal volume; and rate. The presence or absence of autoPEEP will be noted. During pressure-control ventilation, the flow versus time waveform will be printed from the ventilator using a conventional computer printer for later analysis. The following ventilator settings will be recorded: inspiratory pressure; PEEP; and expired tidal volume. |
Who may qualify
- Ages
- 18 to 99 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Inclusion Criteria Subjects may be included in the study if they meet the following inclusion criterion and no exclusion criteria: [1] Adult medical or surgical ICU patients who are mechanically ventilated. Using a random number generator each subject will be assigned to pressure control or volume control for initial set of measurements.
Key inclusion criteria (2 listed)
- Subjects may be included in the study if they meet the following inclusion criterion and no exclusion criteria:
- Adult medical or surgical ICU patients who are mechanically ventilated.
Key exclusion criteria (7 listed)
- Subjects with planned extubation at time of screening
- Subjects who are judged too hemodynamically unstable by their attending physician to participate in the study
- Subjects on high-frequency ventilation
- Subjects whose oxyhemoglobin saturation cannot be maintained at 88% or greater
- Subjects with large air leaks around the endotracheal or tracheostomy tube
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Outcome measure: resistance and compliance measured during pressure control versus volume control ventilation
Time frame: duration of study
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Feb 2017.
Related trials for Respiration Disorders
Enrolling by invitation
Personalized Ventilator Settings for Patients on ECMO
Acute Respiratory Distress Syndrome (ARDS), Extracorporeal Membrane Oxygenation
Not yet recruiting
Miniature In-line Respirator
Brain Death, Respiration, Artificial
Active, not recruiting
CT for Personalized Mechanical Ventilation
Ventilator-Induced Lung Injury, Sepsis Syndrome
Not yet recruiting
Effect of Box Breathing Exercise on Anxiety, Pain, and Pulmonary Function Tests in Patients Undergoing Colonoscopy
Colonoscopy
Not yet recruiting
nCPAP-NAVA-Backup Versus Standard nCPAP for Severe Apnea in Preterm Infants ≤28 Weeks
Apnea of Prematurity
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Respiration Disorders, run by Gregory A. Schmidt at 1 site 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 2 inclusion and 7 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 28 Feb 2017. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Outcome measure: resistance and compliance measured during pressure control versus volume control ventilation (time frame: duration of study). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 28 Feb 2017.