1. Clinical Presentation 63 yo man Hemicolectomy (right) cecal carcinoma Past History: –Anemia, chronic stable angina, GERD Medications: –Diltiazem, Losec No allergies, non-smoker

2. Post-Operative Course Uneventful operation – laparoscopic Post-extubation dyspnea + cough + wheeze Respiratory distress with desaturation RR 36/min SpO 2 80’s – FiO2 increased to 0.4

3. Investigations Chest X-ray Spirometry ABG’s on 0.28 Sputum g/s + C&S ECG/troponin Bilateral opacities FEV 1.46(44%) FVC 1.98(52%) 7.38/38/56/24 Few pus cells Non-specific, normal

4. Diagnosis Asthma Aspiration Cardiogenic pulmonary edema Non-cardiogenic pulmonary edema Fluid overload Pulmonary embolism Hospital acquired pneumonia

5. Management Pulmonary edema – Mueller manoeuvre –Negative pressure pulmonary edema –Forced inspiration with closed glottis –Associated with stridor post-extubation –Rx oxygen, diuretic Aspiration –Rx antibiotics, oxygen,

6. Follow-Up Diuresis 1.2 L post furosemide 40 mg iv At 4 hours, SpO2 94% on room air Admitted for observation, serial troponins Chest X-Ray next day - clear

7. Case Presentation II 53 yo woman undergoing elective hysterectomy Pre-operative assessment: –Hypertension, –Allergies to HDM, pollens –Hay fever treated with anti-histamines At induction – severe increase in inspiratory pressures, difficult to ventilate, bagged OR cancelled

8. Issues “negative” medical history – had asthma as a child and young adult – no problem in recent years – no inhaler use Medications used for induction - Uneventful intubation, no trauma, no aspiration

9. More Issues No risk factors for cardiovascular disease other than treated hypertension No recent URTI No asymmetry in chest findings (that might suggest pneumothorax) Bilateral wheezes, no crackles

10. Diagnosis Asthma Aspiration Cardiogenic pulmonary edema Non-cardiogenic pulmonary edema Pulmonary embolism Hospital acquired pneumonia

11. Management Chest X-Ray normal Rx salbutamol 4 puffs via Aerochamber –SoluMedrol 40 mg iv –Symbicort 200/6 2 puffs BID D/C – to be seen in clinic

12. Follow-Up Well, no symptoms Normal examination, no wheezes Spirometry normal Does she have asthma?

13. Follow-Up II Asthma – variable airflow obstruction –Airway inflammation –Bronchoconstriction May have normal airflow – if well-treated or no exposure to irritants/stimuli Variable airflow obstruction documented by –Baseline AFO improved acutely by B-agonist –Inducible AFO – methacholine challenge – PC 20

14. Follow-Up III PC 20 – 1.25 mg/ml (Normal >16 mg/ml) –severe increase in bronchial responsiveness Rx Symbicort 200/6 2 puffs BID + prn OR re-scheduled and completed uneventfully

15. Post-operative Day 4

16. Atelectasis

17. Duggan M, Kavanagh BP. Pulmonary Atelectasis. Anesthesiology 2005;102:838-54. 90% of patients undergoing GA Alveolar collapse, reduced lung compliance, impaired gas exchange (O 2 ) –Compression –Absorption of alveolar air –Impaired surfactant function

18. Atelectasis Compression –Diaphragm dysfunction - reduced transmural Pr –Reduced FRC –Intercostal muscles and inhalational agents Absorption –Trapped pocket of gas – increases with FiO 2 –Areas of low V A /Q + high FiO 2 + duration Surfactant impairment (=least relevant) –Physical or chemical factors

19. Atelectasis Effect of position –Upright – supine reduces FRC 0.5-1L –Greater reduction if Trendelenburg Atelectasis reduced by –Avoiding 100% Oxygen, use >30% Nitrogen –Lung recruitment manoeuvers –cPAP –Any incentive to deep breath and cough –?Laparoscopic surgery instead of open? –?with better pain control?

20. Complications Hypoxemia Tachypnea, low tidal volume Reduced cough and mucociliary clearance Acute lung injury – cytokine release –Physical, ARDS Lobar collapse Pneumonia

21. Treatment Sit up Move Encourage or force deep breathing –Breathing exercises, IPPV/cPAP, physiotherapy, incentive spirometry Sternal traction