THORACICS

Question 1

Indications for one lung ventilation

Answer 1

ABSOLUTE
 - prevent damage or contamination of healthy lung
 - control distribution of ventilation
    eg bronchopulmonary fistula
 - facilitate bronchopulmonary lavage
   eg CF

RELATIVE

• improve surgical access (strong)
  
  • thoracic aortic aneurysm, pneumonectomy, VATS
• surgical access (weak)
  
  • oesphageal surgery, mediastinal mass reduction

Question 2

Techniques for one lung ventilation

Answer 2

1) DLT - goldstandard
2) Bronchial Blocker
3) SLT placed endobronchially

Question 3

Advantages and Disadvantages of OLV with each airway device.

Answer 3

DLT
-Advantages -
quickest to place?, suction and bronchoscopy to the isolated lung, CPAP to operated llung, can alternate OLV to either lung, can insert even if FOB not available

Disadvantages
Limited sizes, difficult to place in abnormal/distorted airways, not ideal postoperative ventilation, potential airway trauma, intraoperative displacement

Bronchial Blockers
easy size selection, easily used with standard ETT, easier placement in difficult airway easier, selective lobar isolation. post op dual lung ventilation by simply removing blocker

Disadvantages
FOB essential, more time for accurate insertion and placement, slow and incomplete collapse of lung, suction not possible, bronch of isolated lung not possible.

SLT into bronchus
Advatge - easily placed in emergency and difficult airways

Disadvantage - bronch, suction and cpap impossible to isolated lung. difficult for left OLV

Question 4

Discuss management of hypoxaemia during OLV

Answer 4

immediately after OLV there is a fall in SpO2
which improves as HPV increases
Usually biphasic secs to 15mins then second phase 30mins later and peaking at 2 hrs. Aim SpO2 >90

1) Increase FiO2 100% (except bleomycin)
2) Recheck positioning DLT/BB
3) ensure haemodynamics are optimal
4) recruitment manoeuvre ventilated lung - could make it worse for a bit
5) adjust PEEP ventilated ling (caution COPD)
6) insufflation of O2 + PEEP in non-ventilated lung
7) intermittent reinflation of non ventilated lung
8) mechanical restriction of blood flow to non ventilated lung by surgeons
9) if sudden and severe - resume two lung ventilation.