Pre existing respiratory conditions. Amber Woodcock

Contents Respiratory system Post operative pulmonary complications Conditions/risk factors which predispose OSA COPD Asthma Pre op optimisation

Respiratory system Main functions: Oxygenation of blood Removal of carbon dioxide Produce a cough Adjust respiratory rate to accommodate for problems, eg acidosis, pyrexia etc. Image from clipart

Post operative pulmonary complications (PPC’S) Various but some include: Pneumonia Aspiration pneumonitis Pleural effusion Re-intubation Bronchospasm Pneumothorax And others….. Image from clipart

Pre existing risk factors for PPC’s Age Smoker Obesity Current respiratory problem Current respiratory symptoms Resting saturations on air <92 % Co-morbidities Image from clipart

Obstructive sleep apnoea (OSA) Apnoeas – no breathing for 10 secs Hypopnoeas – 50% > airflow reduction for 10 secs. More common in obese men Due to peripheral and central factors (not fully understood). Large number of people undiagnosed Associated problems – pulmonary hypertension, polycythaemia, Hypertension, hypercarbia and hypoxia. Image from clipart

OSA - screening Stop bang criteria - http://www.sleepmd.us/sleep-apnea.html. Image from clipart

OSA – Risks and recomendations for anaesthesia Recommendations Increased mortality and morbidity Poor laryngoscopy views Difficult to ventilate Loss of airway completely Sleep studies to confirm diagnosis – overnight saturations Weight loss Avoid benzodiazepenes Ask patient to bring CPAP machine with them to hospital Extubate fully upright and avoid supine position Avoid LMA Local/regional blocks preferable over GA.

Chronic obstructive pulmonary disease (COPD) Progressive inflammation/parenchymal destruction and partial reversibility. Often due to smoking Dyspnoea/productive cough/wheeze Reduced ability to do ADL’s Co-morbidities/complications- Cor pulmonale, polycythaemia etc.

COPD assessment - Spirometry

COPD Risks Recommendations Bronchospasm – often at induction/maintenance Pneumothorax (bullae) V/Qmismatch Sputum plugging/lobar collapse Ongoing support needed Breath stacking Increased salbutamol prior to operation CXR prior to operation Supplemental oxygen during procedure Positive pressure ventilation Saline nebulisers Suctioning/Chest physiotherapy Adequate analgesia to enable cough Low respiratory rate on ventilator to allow for expiration Regular ABG Consider HDU bed post op

Pre-operative optimisation Arrange appropriate investigations – overnight oximetry, CXR, spirometry, stair climbing etc. Smoking cessation – ideally done at least 8 weeks in advance, as causes increased mucus production initially. Lose weight – reduces risk of sleep apnoea and improves airway management. Treat infections and ensure adequate recovery time Optimise diagnosed conditions – Inhalers, steroids etc

Asthma Reversible airway obstruction and inflammation Various triggers/allergies Dry cough, wheeze, atopy. Diurnal variation in symptoms. Look at peak flow diary (if has one) Exercise tolerance? Smoker?

Asthma Risks Recommendations Induction bronchospasm High peak airway pressures/Bronchospasm Breath stacking Extubation bronchospasm Avoid atracurium – causes histamine release ++ Deepen anaesthesia – Isoflurane is a bronchodilator Consider Salbutamol before and during surgery Make expiratory time longer Consider smaller tidal volumes Adequate suctioning Anti secretory agents – eg Glycopyyrolate Adequate analgesia

References 1. http://www.sleepmd.us/sleep-apnea.html 2. http://www.aagbi.org/sites/default/files/152-Obstructive-Sleep- Apnoea-and-anaesthesia1.pdf 3. https://www.aagbi.org/sites/default/files/106-Anaesthesia-and- COPD.pdf 4.http://www.aqua.ac.nz/upload/resource/Anaesthesia%20for%20th e%20patient%20with%20respiratory%20disease.pdf 5. Preoperative evaluation and risk management. Parsons, David P. 6. http://bja.oxfordjournals.org/content/103/suppl_1/i57.full