2.3 One Lung Ventilation (OLV) Flashcards
a) What are the indications for ‘one-lung ventilation’ (OLV)? (30%)
> > Isolation of lung to prevent cross-contamination,
e.g. empyema, massive haemorrhage.
> > To control distribution of ventilation,
e.g. for bronchopleural fistula.
> > To facilitate surgery,
e.g. thoracoscopic surgery,
oesophagectomy,
pneumonectomy, lobectomy,
scoliosis surgery.
> > Unilateral lung lavage for ***
treatment of alveolar proteinosis.
b) How can the risks associated with lung resection be quantified preoperatively? (30%)
> > Measure forced expiratory volume in 1 second (FEV1) and
diffusing capacity for carbon monoxide (DLCO).
> > Calculate the predicted postoperative (PPO)
FEV1 and DLCO based
on anatomic calculation,
ventilation/perfusion scans
or CT evaluation.
> > If PPO FEV1 and DLCO are
greater than 60%, the patient is low risk.
> > If PPO FEV1 or DLCO is less than 60%
but both are greater than 30%,
proceed to stair climb or shuttle walk assessment.
If good performance,
the patient is low risk;
if poor performance,
proceed to cardiopulmonary exercise testing.
> > If PPO FEV1 or DLCO is less than 30%,
poor performance on stair climb
or shuttle walk assessment or
high risk according to cardiac evaluation
(including thoracic revised cardiac risk index score),
then proceed to cardiopulmonary exercise testing.
If VO2max is greater than 10 ml/kg/
min, the patient is moderate risk;
if less than 10, the patient is high risk.
c) How would you manage the development of hypoxaemia during OLV? (40%)
Hypoxaemia during any anaesthetic is an emergency situation. Alert the theatre team, request help, conduct simultaneous assessment and management of the patient following an ABC approach.
A:
» 100% oxygen,
take over manual ventilation of patient.**
> > Check for obvious equipment failure**
such as disconnection.
> > Check for double lumen tube or *
bronchial blocker dislodgement.*
> > Check for secretions or blood that may have occluded the tube.*
> > Use bronchoscope to assess
and clear secretions if necessary.*
B:
» Assess for compliance,
capnography waveform, oxygen saturations.
> > Auscultate the chest **
(if feasible whilst patient is draped) and
consider bronchospasm, pneumothorax
of ventilated lung, inadequate paralysis.
C:
» Assess for cardiovascular stability;
check for sources of bleeding.
If assessment is otherwise normal,
the likely cause is the abnormal
lung physiology caused by one-lung ventilation.
Options to manage hypoxia include the following:
> > CPAP or high-frequency oscillatory ventilation to the non-ventilated lung to reduce the shunt effect caused by ongoing perfusion to the nonventilated lung.
> > Intermittent two-lung ventilation.
> > High-frequency jet ventilation to both lungs.
Not an option if need complete lung collapse
or if there are concerns about
cross-contamination.
> > If the surgery is for pneumonectomy, **
early clamping of pulmonary artery
will resolve shunt issues.
> > Increase PEEP to the ventilated,
dependent lung to counteract the
effect of mediastinal weight on
functional residual capacity in the lateral
decubitus position.
> > Decrease PEEP to reduce possible
compression of pulmonary capillaries
by excessive intra-alveolar pressure.
> > Increased airway pressure to
ventilated lung to ensure adequate tidal
volume (however, excessive airway
pressures risk impairing perfusion).
> > Optimise CO and haemoglobin
to ensure oxygen delivery.
Does not improve hypoxia but mitigates its effects.
