5.5 OLV Flashcards
Q5 — One-lung ventilation
a) How can the risks associated with lung resection be quantified preoperatively?
Preop calculate a FEV1 + DLCO
Prediced PPO FEV 1 + DLCO
>60 - low risk
30-60 - perform shuttle walk or stair climb test
if poor performance on these - CPET
or if ppo <30 - CPET
CPET - >10ml/kg/min - moderate risk
<10 - high risk
● ECG.
● CXR.
● ABG —
PaO2 <6kPa associated with poor oxygen saturation (<90%) is high risk;
a drop in saturation with exercise by more than 4% is high risk.
● Pulmonary function tests (PFTs) —
FEV1 <1.5L (for lobectomy) and
<2L (for pulmonectomy) are high risk.
● Diffusion capacity —
DLCO <80% is high risk;
<60% increased mortality.
● Cardiopulmonary exercise testing (CPET) — <15ml/kg/min is high risk;
<10ml/kg/min is associated with increased mortality.
● Quantitative lung scan (V/Q scan) —
for predicted postoperative lung
function (<40% is high risk).
● Simple CPET tests such as the 6-minute walk test (<400m needs further evaluation).
● Cardiac risk should be stratified
b) List any six factors that can lead to the development of high airway pressures during one-lung ventilation (OLV).
● Airway compression (internal or external).
● Secretions.
● Blood.
● Tissue soiling.
● Tube kinking.
● Malposition of the double-lumen tube (DLT) or migration of the blocker.
● Bronchospasm.
● Tension pneumothorax in the dependent (ventilated) side.
● Inadequate depth of anaesthesia and muscle relaxation.*
c) How would you manage the development of hypoxaemia during OLV?
● Confirm tube position (fibreoptic bronchoscopy).
● Increase FiO2.
● Ensure haemodynamic stability — oxygen delivery.
● Optimise haemoglobin — oxygen delivery.
● CPAP of non-dependent lung.
● PEEP in dependent lung.
● Lung recruitment in the dependent (ventilated) side.
● Institution of two-lung ventilation.
● Jet ventilation.
● Clamping of the pulmonary artery on the operated side to reduce shunt.
d) What analgesic methods could be used for thoracic surgeries?
● Epidural analgesia — PCEA.
● Paravertebral analgesia — single shot/continuous.
● Intercostal blocks.
● Wound infusions.
● PCA
