Critically IllREGAPSNCT05531253
Respired Gases in Patients Post Cardiac Surgery
An observational study of Critically Ill and Cardiac Disease, run by University of Oxford at 1 site in United Kingdom.
Trial summary
Certain diseases relating to the heart can only be definitively treated with surgery. When untreated, these can lead to heart failure with a lack of supply of oxygen-rich blood to the tissues, leading to damage to other organs. Adults who undergo heart surgery vary greatly in terms of age and relative health. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Critically Ill, Cardiac Disease, Mitral Valve Disease
- What is being tested?
- Data collection using the Optical Gas Analyser
- How many people
- 25 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 30 Oct 2022to 1 Mar 2025
- 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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult patients receiving mechanical ventilation following cardiac surgery
Who may be able to join
- Participant is willing and able to give informed consent for participation in the study.
- Male and female, aged 18 years or above
- Receiving mechanical ventilation via an endotracheal tube in ICU, directly after cardiac surgery
- Have a pulmonary artery catheter in-situ or receive non-invasive cardiac output monitoring
Who cannot join
- Patient is receiving palliative care
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
John Radcliffe Hospital
Oxford, Oxfordshire, OX3 9DU
About this study
Official title: An Observational Study of the Relationship Between Respired Gases, Mixed Venous Oxygen Content and Cardiac Output in Mechanically Ventilated Patients Post Cardiac Surgery
Certain diseases relating to the heart can only be definitively treated with surgery. When untreated, these can lead to heart failure with a lack of supply of oxygen-rich blood to the tissues, leading to damage to other organs.
Adults who undergo heart surgery vary greatly in terms of age and relative health. This has significant implications when predicting outcomes in the aftermath of surgery. For example, a 90-year-old man with a variety of comorbidities such as diabetes and high cholesterol who requires a heart valve replacement may have an unfavourable chance of surviving the postoperative period when compared to an 18-year-old woman with no significant medical history undergoing the same procedure.
Read more
Almost invariably, patients are admitted to an Intensive Care Unit (ICU) following heart surgery. This is done to facilitate close monitoring of the patients' vital organ functions and to also provide organ support if needed. For the heart, this can include the administration of drugs to help a heart pump forcibly, cause blood vessels to contract and increase blood pressure. Patients who have undergone heart surgery have been placed on a mechanical ventilator, following a tube placed in their windpipe. This form of ventilation often continues in ICU for a period of time, depending on the patient's condition.
One specific type of ICU level monitoring that occurs in patients who have undergone heart surgery is cardiac output monitoring. This involves a thin tube, called a pulmonary artery catheter, that extends from the skin to the heart, via large blood vessels. Cardiac output monitoring is essential in this patient group to guide organ support and to provide information of how well the heart is functioning.
In this observational study, the investigators wish to study patients who have undergone cardiac surgery, are receiving mechanical ventilation and have pulmonary artery catheters inserted. The investigators will collect cardiopulmonary data in these patients and compare these data with values of exhaled and inhaled gases (oxygen and carbon dioxide) over the same time period. This will enable the investigators to investigate the link between cardiopulmonary data and respired gas values.
A better understanding of this link between cardiopulmonary function and oxygen/carbon dioxide values will then inform future studies aiming to determine the effect of various interventions in similar patient groups.
Read the detailed description
The cardiovascular system of patients undergoing major cardiac surgery may be unstable during the immediate post-operative period. The core interventions employed as part of routine cardiothoracic ICU management of such patients include the administration of fluids and blood, cardiac pacing, and inotropic support. All of these therapies can be guided by a knowledge of the patient's cardiac output and mixed venous oxygen saturation (SvO2). Pulmonary artery catheters provide an invasive approach that allows the measurement of SvO2 (by blood sampling) and cardiac output (by thermodilution).
For any particular patient, there is always a trade-off between the risks of placing a pulmonary artery catheter and the advantages that it brings when managing patients whose cardiovascular status may be unstable. The primary objective of this study is to explore whether continuous measurement of respired gas exchange, when coupled with small (clinically insignificant), transient variations in inspired oxygen and alveolar carbon dioxide, can be used to calculate mixed venous oxygenation and cardiac output without pulmonary artery catheterisation. If so, then this might provide the basis for a non-invasive approach by which estimates of these parameters can be obtained in patients for whom the benefits of a placing a pulmonary artery catheter do not outweigh the risks.
In order to know the mixed venous oxygenation and cardiac output, this study needs to be conducted in patients who are undergoing pulmonary artery catheterisation as part of their standard clinical care. Patients receiving non-invasive cardiac output monitoring will also be considered. In relation to this, in the UK there are approximately 34,000 major cardiac surgeries which take place each year. Major surgeries in this context include, but are not limited to, coronary artery bypass grafting (CABG), valve replacement or repair and proximal aortic repairs or reconstruction. Following surgery, these patients will invariably be admitted to a Cardiothoracic Intensive Care Unit (CTICU) for the purposes of close cardiorespiratory monitoring and intervention. Many of the patients admitted to CTICU in the postoperative period will require cardiac output monitoring as well as SvO2 measurement. To facilitate this pulmonary artery (PA) catheters are inserted in the perioperative period or non-invasive cardiac output monitoring is utilised postoperatively. Standard operating procedures in our CTICU involve mixed venous sampling for continuous mixed venous oximetry and modern thermodilution via heated catheter for cardiac output measurements. Arterial blood gas samples are taken approximately every hour while the patient is mechanically ventilated.
If it is possible to use measurements of respired gas exchange to estimate cardiac output and SvO2, then they have to be very accurate. The opportunity to obtain measurements with the required precision has arisen from the development of technology that uses laser absorption spectroscopy to measure gas exchange: the Optical Gas Analyser (OGA).
The predicted cardiac output and mixed venous oxygenation are obtained from the measurements of gas exchange by non-linear regression. This process involves a computational model of the lung and circulation that, given particular physiological parameter values and an overall respired gas flow, can calculate the respired gas flows for oxygen, carbon dioxide and nitrogen. The process of non-linear regression is used progressively to adjust the physiological parameter values of the model until the calculated respired gas flows from the model closely match those measured with the OGA. The parameters of the model then provide the cardiac output and SvO2.
In terms of comparators, thermodilution via pulmonary artery catheterisation is generally considered the 'practical' gold standard for measurement of cardiac output in clinical practice. These measurements are available from the pulmonary artery catheter as part of standard clinical care. However, the direct Fick approach is really the true gold standard for the measurement of cardiac output. This requires the mixed venous oxygen content (from the pulmonary artery catheter), the arterial oxygen content (from arterial blood gas measurements) and the oxygen consumption of the patient. The last of these measurements is not available clinically, and this makes the direct Fick method impractical for uses in standard clinical care. Of note, the OGA will supply this measurement, and so a calculation of cardiac output by the direct Fick approach should also be possible in this study.
In summary, A better understanding of the cardiorespiratory changes that occur in post cardiac surgery patients undergoing mechanical ventilation will aid future studies seeking to determine how best to guide various forms of therapy. This will, hopefully, lead to better medical care and improved outcomes in this patient group.
- Conditions
- Critically Ill, Cardiac Disease, Mitral Valve Disease
- Being tested
- Data collection using the Optical Gas Analyser
- Keywords
- pulmonary artery catheter, cardiac output, mixed venous oxygen saturation, oxygen consumption, Fick
- Medical subject headings
- Critical Illness, Heart Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Data collection using the Optical Gas AnalyserOther
To allow the OGA to acquire certain physiological data during the study it will be necessary to slightly vary the tension of oxygen and carbon dioxide for short periods. The changes involved will be of a lesser magnitude than those often seen due to natural variation over time in critically ill patients. The FiO2 will be increased by around 20% from baseline for several minutes; this is a far more modest increase than is seen with the practice of pre-oxygenation - a transitory increase in fraction of inspired oxygen ( FiO2) to 100% - performed regularly in ICU patients to make certain routine interventions safer. The end-tidal CO2 level will also briefly (1-2 min) be altered by around 1 kPa by transient adjustment of the ventilator settings.
| Study group | Role | What they receive |
|---|---|---|
| Main cohort | Patients undergoing cardiac surgery who will have a pulmonary artery catheter in-situ at the time of admission to cardiac intensive care postoperatively. Receives: Other: Data collection using the Optical Gas Analyser |
What is being measured
The primary outcome is the main question the study is designed to answer.
Oxygen (O2)
Measured from the OGA
Measured: Up to 12 hours
Carbon dioxide (CO2)
Measured from the OGA
Measured: Up to 12 hours
Secondary outcomes (2)
Mixed venous oxygen saturation
Measured from pulmonary artery catheter
Measured: Up to 12 hours
Cardiac output
Measured from pulmonary artery catheter or non-invasive cardiac output monitor
Measured: Up to 12 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Sep 2022
- Study start30 Oct 2022
- Primary completion10 Dec 2024
- Study completion1 Mar 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (16)Papers the sponsor has linked to this study.
- Other trials for Critically IllStudies of the same condition, open and under way.
- More trials run by University of OxfordThe sponsor's other registered studies.
- 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
- 25 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Oxford
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, DrDonTishanWellalagodage, University of Oxford
- Investigators
- Peter A Robbins, MBBS DPhil, Study director, University of Oxford
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05531253
- Sponsor's protocol ID
- 16070
- Other IDs
- IRAS 306400
- Acronym
- REGAPS
- Status last verified
- May 2024
- First submitted
- 13 Aug 2022
- Last updated
- 30 Mar 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Bersten A. Oh's intensive care manual. Elsevier; 2014.
National Institute for Cardiovascular Outcomes Research, 2020. National Adult Cardiac Surgery Audit (NACSA) 2020 Summary Report (2016/17-2018/19 data). Healthcare Quality Improvement Partnership.
Savino JS, Hanson CW 3rd, Gardner TJ. Cardiothoracic intensive care: operation and administration. Semin Thorac Cardiovasc Surg. 2000 Oct;12(4):362-70. doi: 10.1053/stcs.2000.20513.
PubMed 11154731Rodriguez Ziccardi M, Khalid N. Pulmonary Artery Catheterization. 2023 Aug 28. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from http://www.ncbi.nlm.nih.gov/books/NBK482170/
PubMed 29489212Cummings B, Hamilton ML, Ciaffoni L, Pragnell TR, Peverall R, Ritchie GA, Hancock G, Robbins PA. Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2. J Appl Physiol (1985). 2011 Jul;111(1):303-7. doi: 10.1152/japplphysiol.00119.2011. Epub 2011 Apr 21.
PubMed 21512147Ciaffoni L, O'Neill DP, Couper JH, Ritchie GA, Hancock G, Robbins PA. In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care. Sci Adv. 2016 Aug 10;2(8):e1600560. doi: 10.1126/sciadv.1600560. eCollection 2016 Aug.
PubMed 27532048Mountain JE, Santer P, O'Neill DP, Smith NMJ, Ciaffoni L, Couper JH, Ritchie GAD, Hancock G, Whiteley JP, Robbins PA. Potential for noninvasive assessment of lung inhomogeneity using highly precise, highly time-resolved measurements of gas exchange. J Appl Physiol (1985). 2018 Mar 1;124(3):615-631. doi: 10.1152/japplphysiol.00745.2017. Epub 2017 Oct 26.
PubMed 29074714Magor-Elliott SRM, Fullerton CJ, Richmond G, Ritchie GAD, Robbins PA. A dynamic model of the body gas stores for carbon dioxide, oxygen, and inert gases that incorporates circulatory transport delays to and from the lung. J Appl Physiol (1985). 2021 May 1;130(5):1383-1397. doi: 10.1152/japplphysiol.00764.2020. Epub 2021 Jan 21.
PubMed 33475459Pugsley J, Lerner AB. Cardiac output monitoring: is there a gold standard and how do the newer technologies compare? Semin Cardiothorac Vasc Anesth. 2010 Dec;14(4):274-82. doi: 10.1177/1089253210386386. Epub 2010 Nov 7.
PubMed 21059611De Maria AN, Raisinghani A. Comparative overview of cardiac output measurement methods: has impedance cardiography come of age? Congest Heart Fail. 2000 Mar-Apr;6(2):60-73. doi: 10.1111/j.1527-5299.2000.80139.x.
PubMed 12029189Wilkes AR. Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients. Anaesthesia. 2011 Jan;66(1):40-51. doi: 10.1111/j.1365-2044.2010.06564.x. Epub 2010 Nov 30.
PubMed 21118189Davis K Jr, Evans SL, Campbell RS, Johannigman JA, Luchette FA, Porembka DT, Branson RD. Prolonged use of heat and moisture exchangers does not affect device efficiency or frequency rate of nosocomial pneumonia. Crit Care Med. 2000 May;28(5):1412-8. doi: 10.1097/00003246-200005000-00026.
PubMed 10834688Djedaini K, Billiard M, Mier L, Le Bourdelles G, Brun P, Markowicz P, Estagnasie P, Coste F, Boussougant Y, Dreyfuss D. Changing heat and moisture exchangers every 48 hours rather than 24 hours does not affect their efficacy and the incidence of nosocomial pneumonia. Am J Respir Crit Care Med. 1995 Nov;152(5 Pt 1):1562-9. doi: 10.1164/ajrccm.152.5.7582295.
PubMed 7582295Thomachot L, Vialet R, Viguier JM, Sidier B, Roulier P, Martin C. Efficacy of heat and moisture exchangers after changing every 48 hours rather than 24 hours. Crit Care Med. 1998 Mar;26(3):477-81. doi: 10.1097/00003246-199803000-00018.
PubMed 9504575Thomachot L, Leone M, Razzouk K, Antonini F, Vialet R, Martin C. Randomized clinical trial of extended use of a hydrophobic condenser humidifier: 1 vs. 7 days. Crit Care Med. 2002 Jan;30(1):232-7. doi: 10.1097/00003246-200201000-00033.
PubMed 11902268
Study at a glance
From the registry record, last updated by the sponsor on 30 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An Observational Study of the Relationship Between Respired Gases, Mixed Venous Oxygen Content and Cardiac Output in Mechanically Ventilated Patients Post Cardiac Surgery
- ClinicalTrials.gov ID
- NCT05531253
- Acronym / sponsor ID
- REGAPS / 16070
- Conditions
- Critically Ill, Cardiac Disease, Mitral Valve Disease
- Keywords
- pulmonary artery catheter, cardiac output, mixed venous oxygen saturation, oxygen consumption, Fick
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 25 participants (actual)
- Lead sponsor
- University of OxfordUniversity, hospital or other
- Study start
- 30 Oct 2022 (actual)
- Primary completion
- 10 Dec 2024 (actual)
- Study completion
- 1 Mar 2025 (actual)
- First posted
- 7 Sep 2022 (actual)
- 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.
Certain diseases relating to the heart can only be definitively treated with surgery. When untreated, these can lead to heart failure with a lack of supply of oxygen-rich blood to the tissues, leading to damage to other organs.
Adults who undergo heart surgery vary greatly in terms of age and relative health. This has significant implications when predicting outcomes in the aftermath of surgery. For example, a 90-year-old man with a variety of comorbidities such as diabetes and high cholesterol who requires a heart valve replacement may have an unfavourable chance of surviving the postoperative period when compared to an 18-year-old woman with no significant medical history undergoing the same procedure.
Almost invariably, patients are admitted to an Intensive Care Unit (ICU) following heart surgery. This is done to facilitate close monitoring of the patients' vital organ functions and to also provide organ support if needed. For the heart, this can include the administration of drugs to help a heart pump forcibly, cause blood vessels to contract and increase blood pressure. Patients who have undergone heart surgery have been placed on a mechanical ventilator, following a tube placed in their windpipe. This form of ventilation often continues in ICU for a period of time, depending on the patient's condition.
One specific type of ICU level monitoring that occurs in patients who have undergone heart surgery is cardiac output monitoring. This involves a thin tube, called a pulmonary artery catheter, that extends from the skin to the heart, via large blood vessels. Cardiac output monitoring is essential in this patient group to guide organ support and to provide information of how well the heart is functioning.
In this observational study, the investigators wish to study patients who have undergone cardiac surgery, are receiving mechanical ventilation and have pulmonary artery catheters inserted. The investigators will collect cardiopulmonary data in these patients and compare these data with values of exhaled and inhaled gases (oxygen and carbon dioxide) over the same time period. This will enable the investigators to investigate the link between cardiopulmonary data and respired gas values.
A better understanding of this link between cardiopulmonary function and oxygen/carbon dioxide values will then inform future studies aiming to determine the effect of various interventions in similar patient groups.
Detailed description
The cardiovascular system of patients undergoing major cardiac surgery may be unstable during the immediate post-operative period. The core interventions employed as part of routine cardiothoracic ICU management of such patients include the administration of fluids and blood, cardiac pacing, and inotropic support. All of these therapies can be guided by a knowledge of the patient's cardiac output and mixed venous oxygen saturation (SvO2). Pulmonary artery catheters provide an invasive approach that allows the measurement of SvO2 (by blood sampling) and cardiac output (by thermodilution).
For any particular patient, there is always a trade-off between the risks of placing a pulmonary artery catheter and the advantages that it brings when managing patients whose cardiovascular status may be unstable. The primary objective of this study is to explore whether continuous measurement of respired gas exchange, when coupled with small (clinically insignificant), transient variations in inspired oxygen and alveolar carbon dioxide, can be used to calculate mixed venous oxygenation and cardiac output without pulmonary artery catheterisation. If so, then this might provide the basis for a non-invasive approach by which estimates of these parameters can be obtained in patients for whom the benefits of a placing a pulmonary artery catheter do not outweigh the risks.
In order to know the mixed venous oxygenation and cardiac output, this study needs to be conducted in patients who are undergoing pulmonary artery catheterisation as part of their standard clinical care. Patients receiving non-invasive cardiac output monitoring will also be considered. In relation to this, in the UK there are approximately 34,000 major cardiac surgeries which take place each year. Major surgeries in this context include, but are not limited to, coronary artery bypass grafting (CABG), valve replacement or repair and proximal aortic repairs or reconstruction. Following surgery, these patients will invariably be admitted to a Cardiothoracic Intensive Care Unit (CTICU) for the purposes of close cardiorespiratory monitoring and intervention. Many of the patients admitted to CTICU in the postoperative period will require cardiac output monitoring as well as SvO2 measurement. To facilitate this pulmonary artery (PA) catheters are inserted in the perioperative period or non-invasive cardiac output monitoring is utilised postoperatively. Standard operating procedures in our CTICU involve mixed venous sampling for continuous mixed venous oximetry and modern thermodilution via heated catheter for cardiac output measurements. Arterial blood gas samples are taken approximately every hour while the patient is mechanically ventilated.
If it is possible to use measurements of respired gas exchange to estimate cardiac output and SvO2, then they have to be very accurate. The opportunity to obtain measurements with the required precision has arisen from the development of technology that uses laser absorption spectroscopy to measure gas exchange: the Optical Gas Analyser (OGA).
The predicted cardiac output and mixed venous oxygenation are obtained from the measurements of gas exchange by non-linear regression. This process involves a computational model of the lung and circulation that, given particular physiological parameter values and an overall respired gas flow, can calculate the respired gas flows for oxygen, carbon dioxide and nitrogen. The process of non-linear regression is used progressively to adjust the physiological parameter values of the model until the calculated respired gas flows from the model closely match those measured with the OGA. The parameters of the model then provide the cardiac output and SvO2.
In terms of comparators, thermodilution via pulmonary artery catheterisation is generally considered the 'practical' gold standard for measurement of cardiac output in clinical practice. These measurements are available from the pulmonary artery catheter as part of standard clinical care. However, the direct Fick approach is really the true gold standard for the measurement of cardiac output. This requires the mixed venous oxygen content (from the pulmonary artery catheter), the arterial oxygen content (from arterial blood gas measurements) and the oxygen consumption of the patient. The last of these measurements is not available clinically, and this makes the direct Fick method impractical for uses in standard clinical care. Of note, the OGA will supply this measurement, and so a calculation of cardiac output by the direct Fick approach should also be possible in this study.
In summary, A better understanding of the cardiorespiratory changes that occur in post cardiac surgery patients undergoing mechanical ventilation will aid future studies seeking to determine how best to guide various forms of therapy. This will, hopefully, lead to better medical care and improved outcomes in this patient group.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Main cohort | – | Other: Data collection using the Optical Gas AnalyserPatients undergoing cardiac surgery who will have a pulmonary artery catheter in-situ at the time of admission to cardiac intensive care postoperatively. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult patients receiving mechanical ventilation following cardiac surgery
Key inclusion criteria (4 listed)
- Participant is willing and able to give informed consent for participation in the study.
- Male and female, aged 18 years or above
- Receiving mechanical ventilation via an endotracheal tube in ICU, directly after cardiac surgery
- Have a pulmonary artery catheter in-situ or receive non-invasive cardiac output monitoring
Key exclusion criteria (1 listed)
- Patient is receiving palliative care
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Data collection using the Optical Gas AnalyserTo allow the OGA to acquire certain physiological data during the study it will be necessary to slightly vary the tension of oxygen and carbon dioxide for short periods. The changes involved will be of a lesser magnitude than those often seen due to natural variation over time in critically ill patients. The FiO2 will be increased by around 20% from baseline for several minutes; this is a far more modest increase than is seen with the practice of pre-oxygenation - a transitory increase in fraction of inspired oxygen ( FiO2) to 100% - performed regularly in ICU patients to make certain routine interventions safer. The end-tidal CO2 level will also briefly (1-2 min) be altered by around 1 kPa by transient adjustment of the ventilator settings. | Other | Main cohort |
Primary outcome
Oxygen (O2)
Time frame: Up to 12 hours
Measured from the OGA
Carbon dioxide (CO2)
Time frame: Up to 12 hours
Measured from the OGA
2 secondary outcomes
Mixed venous oxygen saturation
Time frame: Up to 12 hours
Cardiac output
Time frame: Up to 12 hours
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 30 Mar 2025.
- BackgroundBersten A. Oh's intensive care manual. Elsevier; 2014.
- BackgroundNational Institute for Cardiovascular Outcomes Research, 2020. National Adult Cardiac Surgery Audit (NACSA) 2020 Summary Report (2016/17-2018/19 data). Healthcare Quality Improvement Partnership.
- Background: PubMed 11154731Savino JS, Hanson CW 3rd, Gardner TJ. Cardiothoracic intensive care: operation and administration. Semin Thorac Cardiovasc Surg. 2000 Oct;12(4):362-70. doi: 10.1053/stcs.2000.20513.
- Background: PubMed 29489212Rodriguez Ziccardi M, Khalid N. Pulmonary Artery Catheterization. 2023 Aug 28. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from http://www.ncbi.nlm.nih.gov/books/NBK482170/
- Background: PubMed 21512147Cummings B, Hamilton ML, Ciaffoni L, Pragnell TR, Peverall R, Ritchie GA, Hancock G, Robbins PA. Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2. J Appl Physiol (1985). 2011 Jul;111(1):303-7. doi: 10.1152/japplphysiol.00119.2011. Epub 2011 Apr 21.
- Background: PubMed 27532048Ciaffoni L, O'Neill DP, Couper JH, Ritchie GA, Hancock G, Robbins PA. In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care. Sci Adv. 2016 Aug 10;2(8):e1600560. doi: 10.1126/sciadv.1600560. eCollection 2016 Aug.
- Background: PubMed 29074714Mountain JE, Santer P, O'Neill DP, Smith NMJ, Ciaffoni L, Couper JH, Ritchie GAD, Hancock G, Whiteley JP, Robbins PA. Potential for noninvasive assessment of lung inhomogeneity using highly precise, highly time-resolved measurements of gas exchange. J Appl Physiol (1985). 2018 Mar 1;124(3):615-631. doi: 10.1152/japplphysiol.00745.2017. Epub 2017 Oct 26.
- Background: PubMed 33475459Magor-Elliott SRM, Fullerton CJ, Richmond G, Ritchie GAD, Robbins PA. A dynamic model of the body gas stores for carbon dioxide, oxygen, and inert gases that incorporates circulatory transport delays to and from the lung. J Appl Physiol (1985). 2021 May 1;130(5):1383-1397. doi: 10.1152/japplphysiol.00764.2020. Epub 2021 Jan 21.
- Background: PubMed 21059611Pugsley J, Lerner AB. Cardiac output monitoring: is there a gold standard and how do the newer technologies compare? Semin Cardiothorac Vasc Anesth. 2010 Dec;14(4):274-82. doi: 10.1177/1089253210386386. Epub 2010 Nov 7.
- Background: PubMed 12029189De Maria AN, Raisinghani A. Comparative overview of cardiac output measurement methods: has impedance cardiography come of age? Congest Heart Fail. 2000 Mar-Apr;6(2):60-73. doi: 10.1111/j.1527-5299.2000.80139.x.
- Background: PubMed 21118189Wilkes AR. Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 - practical use, including problems, and their use with paediatric patients. Anaesthesia. 2011 Jan;66(1):40-51. doi: 10.1111/j.1365-2044.2010.06564.x. Epub 2010 Nov 30.
- Background: PubMed 10834688Davis K Jr, Evans SL, Campbell RS, Johannigman JA, Luchette FA, Porembka DT, Branson RD. Prolonged use of heat and moisture exchangers does not affect device efficiency or frequency rate of nosocomial pneumonia. Crit Care Med. 2000 May;28(5):1412-8. doi: 10.1097/00003246-200005000-00026.
- Individual participant dataSharing planned: No
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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.
Peter A Robbins, MBBS DPhil study director
University of Oxford
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 Critically Ill and Cardiac Disease, run by University of Oxford at 1 site in United Kingdom.
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 4 inclusion and 1 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 30 Mar 2025. 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 Kingdom. 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?
Oxygen (O2) (time frame: Up to 12 hours). The study lists 2 primary outcomes in all. 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 NCT05531253, which also lists 16 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 30 Mar 2025.