Oxygen Consumption in Critical Illness

Measurement of Oxygen Consumption in Critical Illness Using Optical Gas Analysis

Many serious illnesses are characterised by a lack of oxygen delivery to the body's tissues. This can be due to problems with the circulation, such as when the heart fails to pump blood efficiently or if the blood pressure is very low, or due to changes in the lungs preventing them from transferring oxygen effectively from the air into the blood.

Many of the treatments used in critically ill patients are aimed at improving the supply of oxygen-rich blood to the tissues. These include drugs to increase the blood pressure or make the heart pump more forcibly, blood transfusions to increase the amount of oxygen that the blood can carry, and ventilators (breathing machines) to help the lungs introduce more oxygen into the bloodstream. Decisions to use such treatments are based on a number of factors. One of the most important is an assessment of how much oxygen an individual patient is using at a given time. Whilst it is possible to measure average oxygen consumption over a long period of time in healthy individuals, the equipment and techniques needed are simply not practical for routine use in the clinical setting of a critical care unit. Critical care doctors and nurses therefore have to rely on a number of different indicators of the adequacy of the amount of oxygen that is being provided in order to make decisions about how best to treat patients. Unfortunately, all of these have their limitations, are affected by other treatments patients may be receiving, and can be difficult to interpret. Examples include 'mixed venous oxygen saturation' (SvO2), that is the amount of oxygen in the blood coming back to the lungs from the body, ready to have more oxygen added, and blood lactate levels, which give an indication of whether the tissues have enough oxygen to produce the energy they need to function in an efficient manner.

Our group has developed a device which can be added easily to the normal equipment used on a critical care ward when a patient is on a ventilator, which can accurately and rapidly measure the amount of oxygen the individual is consuming.

This study will provide us with data so the investigators can define a "normal" range of oxygen consumption in these patients, and treatments which alter consumption. In a future study, once the investigators know what the normal range is, they can introduce new techniques to improve oxygen consumption in those patients whose consumption is less than ideal.

Study Overview

• Status: Unknown
• Conditions: Critical Illness

Detailed Description

This is a prospective longitudinal observational study in thirty intubated, ventilated patients. Patients will be recruited from the population of already intubated and ventilated individuals on an adult intensive care unit (AICU). Once patients have been recruited we will insert the optical gas analyser (OGA) into the ventilation circuit (tubing) for 48 hours.

Data will be continuously collected until 48 hours from attachment of the OGA, death or extubation of the patient, and analysed retrospectively. A time series describing oxygen consumption with a resolution of one minute or less will be prepared and standard measures of dispersion calculated. In addition, variables that are routinely recorded on the computerised clinical record during the same period will then be examined and associations sought between these variables and changes in oxygen consumption as measured with the OGA. We have prospectively identified variables which, based on the published literature, are likely to be associated with variation in oxygen consumption (VO2) upon which attention will focus, though others may become apparent during the study:

• Body temperature
• Seizures
• Change in haemoglobin concentration (including due to blood transfusion)
• Bolus fluids
• Vasoactive drugs
• Beta-agonist drugs
• Drugs affecting the angiotensin-converting enzyme system
• Renal replacement therapy
• Feeding
• Sedation
• Neuromuscular blockers
• Mode of ventilation
• Fraction of inspired oxygen (FiO2)
• Physical activity
• Surgery

• Study Type: Observational
• Enrollment (Anticipated): 30

Contacts and Locations

Study Locations

• United Kingdom
  • Oxfordshire
    • Oxford, Oxfordshire, United Kingdom, OX3 9DU
      • Recruiting
      • Oxford Univerity Hospital NHS Trust, John Radcliffe Hospital
      • Contact: John D Young, DM; Phone Number: 01865220621; Email: duncan.young@nda.ox.ac.uk
      • Contact: Matthew C Frise, BMBCh; Phone Number: 01865282357; Email: matthew.frise@dpag.ox.ac.uk
      • Sub-Investigator: Matthew C Frise, BMBCh
      • Principal Investigator: John D Young, DM

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Adult patients requiring intubation and mechanical ventilation on an adult intensive care unit

Description

Inclusion Criteria:

• Male and female patients aged 18 years or over
• Admitted to an adult intensive care unit
• Expected duration of intubation and mechanical ventilation of at least 48 hours

Exclusion Criteria:

• Consultee indicates patient would be likely to decline enrolment
• Patient is receiving palliative care
• Use of active cooling
• Heavy sputum production (or other indication) necessitating use of an active humidifier in ventilator circuit

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort
Critically-ill patients; Adult patients requiring intubation and mechanical ventilation on an intensive care unit, predicted to require a further 48 hours of artificial ventilation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Oxygen consumption	Within patient oxygen consumption over time correlated with changes in physiological variables and treatment received	Up to 48 hours

Collaborators and Investigators

• Sponsor: University of Oxford
• Collaborators: National Institute for Health Research, United Kingdom
• Investigators: Principal Investigator: John D Young, DM, University of Oxford and Oxford University Hospitals NHS Trust

Publications and helpful links

General Publications

• Rivers E, Nguyen B, Havstad S, Ressler J, Muzzin A, Knoblich B, Peterson E, Tomlanovich M; Early Goal-Directed Therapy Collaborative Group. Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med. 2001 Nov 8;345(19):1368-77. doi: 10.1056/NEJMoa010307.
• Cummings 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.
• Shoemaker WC, Appel PL, Kram HB. Hemodynamic and oxygen transport responses in survivors and nonsurvivors of high-risk surgery. Crit Care Med. 1993 Jul;21(7):977-90. doi: 10.1097/00003246-199307000-00010.
• Hayes MA, Timmins AC, Yau EH, Palazzo M, Hinds CJ, Watson D. Elevation of systemic oxygen delivery in the treatment of critically ill patients. N Engl J Med. 1994 Jun 16;330(24):1717-22. doi: 10.1056/NEJM199406163302404.
• ProCESS Investigators, Yealy DM, Kellum JA, Huang DT, Barnato AE, Weissfeld LA, Pike F, Terndrup T, Wang HE, Hou PC, LoVecchio F, Filbin MR, Shapiro NI, Angus DC. A randomized trial of protocol-based care for early septic shock. N Engl J Med. 2014 May 1;370(18):1683-93. doi: 10.1056/NEJMoa1401602. Epub 2014 Mar 18.
• Shoemaker WC, Appel PL, Kram HB, Waxman K, Lee TS. Prospective trial of supranormal values of survivors as therapeutic goals in high-risk surgical patients. Chest. 1988 Dec;94(6):1176-86. doi: 10.1378/chest.94.6.1176.

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2015
• Primary Completion (Anticipated): March 1, 2019
• Study Completion (Anticipated): March 1, 2020

Study Registration Dates

• First Submitted: June 9, 2014
• First Submitted That Met QC Criteria: June 12, 2014
• First Posted (Estimate): June 13, 2014

Study Record Updates

• Last Update Posted (Actual): May 8, 2018
• Last Update Submitted That Met QC Criteria: May 2, 2018
• Last Verified: May 1, 2018

More Information

Terms related to this study

• Keywords: Cardiac output; Oxygen consumption; Pulmonary gas exchange
• Additional Relevant MeSH Terms: Pathologic Processes; Disease Attributes; Critical Illness
• Other Study ID Numbers: 14/EE/0003