EXPIRED GAS ANALYSIS DURING EXERCISE TESTING
AS A RISK ASSESSMENT METHOD IN
NONCARDIOPULMONARY
SURGERY
By
JANAN ABDALRAZZAK NOMAN
A thesis submitted in partial fulfilment of the requirement
of Glasgow Caledonian
University for the degree of Doctor of Philosophy
School of Health and Life Sciences
Department of biological and biomedical sciences
May 2013
ABSTRACT
A total of 459 patients from the Glasgow population with upper gastrointestinal and
vascular disease were included in this study. The majority were over the age of 65 years,
63% were male, 36 % were smokers, 35% were from the most deprived socioeconomic
group and 16% were from the least deprived group.
This study was conducted in two parts. Firstly, all patients underwent cardiopulmonary
exercise testing (CPET), spirometry, transfer factor for carbon monoxide (TLCO) testing
and blood gas analysis. In the second part, all patients were followed up by the electronic
portal system and by examination of case records.
The decision process of whether or not to treat or which treatment is appropriate (e.g.
surgery, neo-adjuvant chemotherapy or chemo-radiotherapy) is based not only on the
kind and activity of the disease but also on patient’s cardiopulmonary fitness.
Many strategies have been shown to determine patients’ fitness in order to decide the
type of treatment. An early approach is the subjective evaluation of the patient by
asking questions on daily living activities, which is generally misleading. Other
approaches such as resting pulmonary and cardiac function testing cannot reliably predict
exercise performance and functional capacity. Another approach has been to provide an
integrated assessment of cardiovascular and pulmonary at rest and during exercise, which
is the cardiopulmonary exercise test (CPET). CPET is an important non-invasive
physiological investigation that can provide a diagnostic evaluation of exercise
intolerance and dyspnoea. During CPET, the patients are exposed to incremental physical
exercise up to their maximally tolerated level, as dictated by exhaustion or symptoms
(dyspnoea or chest pain).
Patients’ cardiorespiratory fitness is affected by many factors including age, sex, obesity
or weight loss, smoking status and lifestyle, therefore this study aimed to examine those
factors which can affect cardiopulmonary fitness. It did this measurement of CPET, static
pulmonary function and blood gas analysis and it examined the role of the use of these
tests in predicting treatment strategy in a cohort of patients with cancer, benign
disease of the upper gastrointestinal tract or vascular disease. The results of the present
study showed that there were a number of patient characteristics including age, sex, BMI
and smoking status associated with alterations in CPET and other related tests parameters
and, even when normalised for age, sex and BMI, remained associated with alterations in
CPET and other related tests parameters. Preoperative CPET, TLCO and pulmonary
function at rest may help in deciding treatment strategy.
Major surgery causes a systemic inflammatory response leading to marked increases in
oxygen consumption immediately postoperatively. Patients with poor cardiopulmonary
reserve, in particular those with medical co-morbidities, may not meet this increase in
oxygen consumption leading to avoidable morbidity and mortality.
Reducing complications and mortality following major surgery remains a significant
challenge for the National Health Service. Identification of those patients who are liable
to postoperative complication is worthwhile for patients and doctors. Patients may benefit
from the opportunity to improve their fitness by for e.g. alterations in drug therapy, an
exercise program or dietary changes. It also gives a greater opportunity for patients and
families to understand, as far as possible, the potential risk of the surgery procedure.
Doctors can provide potential ways of allocating care to patients with high risk. Multiple
strategies have been shown to improve postoperative outcomes. CPET can determine the
ability of the subject’s physiological capacity to cope with metabolic demands created by
major surgery trauma. This test is often conducted for risk stratification before major
surgery, although there is no clear agreement on the best CPET predictor(s) of outcome
(e.g. peak oxygen consumption, anaerobic threshold). Postoperative cardiopulmonary
complications play an important role in the risk for patients undergoing non
cardiopulmonary, in particular, upper gastrointestinal surgery. To date, there have been
few comparative studies of CPET, TLCO, spirometry, blood gas analysis and
anthropometry in perioperative risk assessment, therefore the aim of the present study
was to examine the relationship between preoperative measurements of CPET, resting
pulmonary function tests, blood gas analysis and anthropometry with postoperative
outcomes in patients undergoing major upper gastrointestinal surgery in Glasgow
population. In this study, it was found that CPET, in particular, anaerobic
threshold was an indicator of the development of a post-operative pulmonary
complication. It was found that CPET was not helpful to predict surgical site infective
complications including an anastomotic leak.
Neo-adjuvant chemotherapy has been recommended in the treatment ofgastrooesophageal
malignancy in an attempt to downstage tumor activity in order to enhance resectability
and improve symptoms and survival. There is a continuing controversy about
the advantage of using neoadjuvant chemotherapy in cancer treatment, in term of the
effect of chemotherapy on cardiopulmonary fitness and its association with postoperative
outcomes.
The aim of the present study was to examine the effect of chemotherapy on
cardiopulmonary fitness measured by CPET, resting pulmonary function and blood gas
analysis. It was found that there was no significant change in cardiopulmonary fitness in
patients who underwent chemotherapy as shown by peak oxygen consumption; anaerobic
threshold and resting pulmonary function. This study also aimed to examine the
association between post chemotherapy CPET and pulmonary function tests with
postoperative outcomes in patients with gastro-oesophageal cancer undergoing
neoadjuvant chemotherapy in Glasgow population. It was found that CPET, pulmonary
function testing and related factors were not associated with the development of
postoperative complications in patients who underwent neo-adjuvant chemotherapy. The
patients who developed postoperative complications had a longer high dependency care
stay, ward stay and hospital stay than those who did not develop postoperative
complications.
In upper gastrointestinal disease, early diagnosis is important leading to proper treatment
otherwise the spread of the disease is such that it will reach the level at which doctors
cannot offer treatment for their patients.
The aim of the present study was to find any more roles of CPET and its related factors
from the data of no active treatment patients in the field of abdominal aortic aneurysm
(AAA) and upper gastrointestinal disease. The results of the present study show
that the benign and malignant patients who did not receive active treatment had a low
exercise capacity and low diffusion capacity of the lungs.