The Cost in Oxygen of Surgical Trauma

Study Overview
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Brief Summary
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The investigators will examine the relationship between post-operative oxygen consumption (using non-invasive measurement technology ) and complications in patients having contemporary major abdominal surgery. The investigators hypothesis is that major surgery may trigger a physiological stress response that results in an increase in post-operative metabolic demand and oxygen consumption (V̇O2) which must be met by an increased oxygen delivery (DO2). To determine the feasibility of non-invasive measurement of oxygen consumption (V̇O2) using indirect calorimetry in a cohort of patients To determine the feasibility of non-invasive measurement of oxygen delivery (DO2) in the same cohort using non-invasive measures of cardiac output, oxygen saturation and haemoglobin (pulse wave transit time and co-oximetry techniques)

Detailed Description
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Prospective observational study of non-invasive measurements of V̇O2 and DO2 pre-operatively and at 8 time points in the 48 hours postoperatively in a cohort of 40 patients undergoing elective major abdominal surgery (both open and laparoscopic) with a pre-operative cardiopulmonary exercise testing (CPET). As pilot work examining the relationship between post-operative oxygen consumption and complications in patients having contemporary major abdominal surgery , the investigators need to define and grade the severity of complications. The Post-Operative Morbidity Survey (POMS) is a simple outcome scale designed to record the incidence of clinically important complications - specifically complications likely to keep a patient in hospital. A POMS score performed on Day 5 is likely to be discriminative between patients who are recovering well, and those who are developing complications. POMS is easily performed, has good internal validity and is predictive of a prolonged length of stay. POMS is not a simple additive scale; however patients with POMS score of 1 or greater are highly likely to remain in hospital, whereas those with a score of 0 are likely to be able to go home.

Official Title
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The Cost in Oxygen of Surgical Trauma (CO2ST) - a Feasibility Study of the Non-invasive Measurement of Oxygen Delivery and Consumption After Major Abdominal Surgery

Conditions
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Oxygen Consumption (V̇O2), Oxygen Delivery (DO2), Post-operative Complications

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male and female patients aged 18 or over. Undergoing elective major open or laparoscopic abdominal surgery. Exclusion Criteria: Refusal to participate Requirement for post-operative ventilation Requirement of inspired oxygen concentrations (FiO2) > 28% to maintain oxygen saturations ≥ 90%.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Elective major abdominal surgery<br>Patients undergoing elective major open or laparoscopic abdominal surgery at Plymouth Hospitals National Health Service (NHS) Trust (PHNT) | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| postoperative morbidity score (POMS) | The Post-Operative Morbidity Survey (POMS) is a simple outcome scale designed to record the incidence of clinically important complications - specifically complications likely to keep a patient in hospital. A POMS score performed on Day 5 is likely to be discriminative between patients who are recovering well, and those who are developing complications. POMS is easily performed, has good internal validity and is predictive of a prolonged length of stay. POMS is not a simple additive scale; however patients with POMS score of 1 or greater are highly likely to remain in hospital, whereas those with a score of 0 are likely to be able to go home. | Day 5 post surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Length of hospital stay | The number of days the patient is in hospital following surgery | estimated average length of hospital stay of 5 - 7 days | 
| Unplanned admission to critical care. | We are looking at admission to critical care that was not arranged pre-operatively - a certain proportion of patients are routinely admitted to critical care because of medical co-morbidities. We are looking for those patients who were deemed fit enough not to need critical care post-operatively who subsequently need admission there, and the length of their stay there. | Participants will be followed for the duration of hospital stay, an expected average of 5 - 7 days | 
| Returns to the operating theatre | The number of times a patient has to be returned to the operating theatre during their index admission. | Number of events during Hospital admission (estimated average length of hospital stay of 5 - 7 days) | 
| Hospital readmission | Number of readmissions to hospital following discharge elated to the patients surgery | Within 30 days of discharge from hospital | 
| Mortality | Patient mortality rate following surgery up to 30 days following discharge | Up to 30 days following hospital discharge | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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consumption, non-invasive, measurement of oxygen, delivery, post-operative complications