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
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
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
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
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
Follow-Up Well, no symptoms Normal examination, no wheezes Spirometry normal Does she have asthma?
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
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
Post-operative Day 4
Duggan M, Kavanagh BP. Pulmonary Atelectasis. Anesthesiology 2005;102: % of patients undergoing GA Alveolar collapse, reduced lung compliance, impaired gas exchange (O 2 ) –Compression –Absorption of alveolar air –Impaired surfactant function
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
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?