Hypoxaemia post Cardiac Surgery

OVERVIEW

• this is an unexpected situation post routine cardiac surgery but not uncommon.
• management approach would be based on a systematic assessment of the patient using history, examination and review of investigations with regard to the following possible causes.

CAUSES/PROBLEMS

• inadequate O2 delivery
• endotracheal tube malposition or not patent
• patient: acute lung pathology (atelectasis, collapse, pneumothorax, haemothorax, APO, ALI)
• patient: chronic lung pathology (smoker, COPD, emphysema)
• inadequate cardiac output
• measurement problem

HISTORY

• review notes
• duration and degree of smoking related lung disease (pack years, symptoms, pre-operative spirometry, CXR, ABG)
• intraoperative events (difficulties with ventilation, oxygenation, intubation, aspiration, analphylaxis)
• post operative chest CXR findings
• secretion burden
• haemodynamic trends

EXAMINATION

• ETT position and patency
• tracheal position
• chest expansion, percussion, AE (collapse, consolidation, pneumothorax, haemothorax, bronchospasm)
• cardiac examination: cardiac output, peripheral perfusion, signs of tamponade

INVESTIGATIONS

• CXR: ETT position, lung fields
• PV Loops: airflow obstruction, compliance
• ABG: PaCO2, pH
• ETCO2: slope
• CT chest: rarely indicated but may be of use in a few days

MANAGEMENT

• dependent on findings

Goals:

1. improve oxygenation
2. prevent lung damage (baro, volu, atelect-trauma)
3. treat the underlying cause

• exclude equipment failure and malposition of tube
• drain pneumothorax or pleural fluid
• atelectasis/collapse: recruit, increase PEEP, bronchoscopy
• pulmonary oedema: diuresis, inotropy, PEEP
• optimise cardiac output
• bronchodilators
• lung protective ventilation
• consider antibiotics if indicated

References and Links

LITFL

• CCC – Haemorrhage post-cardiac surgery
• CCC – Hypertension post-cardiac surgery
• CCC – Hypotension post-cardiac surgery
• CCC – Hypothermia post-cardiac surgery