Unrecognised Obstructive Sleep Apnea Study
Unrecognised Obstructive Sleep Apnea Study
Plan of investigation:

 This is an observational cohort study to determine the effect of OSA, independent of other
 risk factors, on postoperative vascular events. The study is conceived, designed and will be
 conducted, and analyzed independent to any company. There is no commercial sponsorship.
The potential study subjects will be approached by study coordinator at preoperative clinic.
 If the patient is interested in participating the study, he/she will be screened and
 consented. Undetected or untreated OSA will be established by STOP-Bang questionnaire and
 subsequent overnight PSG by using Apnea Link Plus which is level ( 2 ) at patient's home.The
 following data will be recorded: including age, gender, history of coronary artery disease,
 prior revascularization, cerebrovascular disease, peripheral vascular disease, critical
 aortic valvular stenosis, congestive heart failure, atrial fibrillation, diabetes treated
 with insulin or an oral diabetic drug, hypertension, hypercholesterolemia treated with drug
 therapy, tobacco use, renal insufficiency and the type of surgery. For all study patients,
 the nocturnal blood oxygen saturation will be monitored by a pulse oximeter (PULSOX 300i) for
 first 3 nights postoperatively.During their stay in hospital, patients will be followed
 daily, and outcomes will be recorded, until discharge.. ECG will be measured preoperatively
 and repeated on day 1 to 3 after surgery. Venous blood will be collected 6-12 hours and on
 the first 3 days after surgery for measuring cTnT concentration.If patient's ECG is abnormal
 and/or patient is positive for troponin test, treating physician will be contacted for
 further treatment. Patient will be contacted 30 days after surgery by phone to ascertain if
 they have experienced any adverse out come.
Patients Inclusion & Exclusion Criteria:

 Inclusion criteria:

 Ethics Committee approval and informed consent will be obtained. We plan to study patients
 at moderate-to-high risk for postoperative vascular complications because our data from
 other trials suggested that the incidence of OSA in these patients is higher than the
 general population. We will include patients who are:

 1. adult males and females, age ≥ 45 years, undergoing elective non-cardiac surgery that
 is expected to require a postoperative hospital stay of more than 3 nights, and

 2. at increased risk for postoperative vascular events, defined as having at least one of
 the following risk factors (a) high-risk surgery (intra-peritoneal, intra-thoracic or
 supra-inguinal vascular surgery); (b) history of ischemic heart disease; (c) history
 of congestive heart failure; (d) history of cerebrovascular disease (d) diabetes
 requiring insulin therapy (e) serum creatinine > 175 µmol/L.

 Exclusion criteria:

 Patients will be excluded if:

 1. they have a previous diagnosis of OSA or any sleep-related breathing disorder and on
 treatment

 2. they are unwilling or physically unavailable for PSG on any night before surgery;

 3. their surgery included tonsillectomy, septoplasty, uvuloplasty, pharyngoplasty,
 tracheostomy, or prolonged (> 48 hrs) postoperative mechanical ventilation of the
 lungs is anticipated. It is because these procedures/interventions are likely to cure
 or at least modify the severity of OSA.