Background: While permissive hypercapnia is commonly practised in critical
care, it remains unclear if the comparable manoeuvres are clinically accept
able during anaesthesia. This retrospective study aimed at describing the a
naesthetic implications of hypercapnia associated with deliberate hypoventi
lation during thoracic surgery in patients with severe emphysema.
Methods: Thirteen patients with emphysema who required thoracic surgery und
er similar anaesthesia were reviewed: 3 patients were managed to maintain n
ormocapnia (normocapnia group) whereas 10 patients developed hypercapnia (P
aCO2 >70 mmHg) as a result of restricting peak airway pressures (hypercapni
a group).
Results: In the normocapnia group (PaCO2: 45+/-1 mmHg, mean+/-SD), no event
which required therapeutic intervention during the surgery was seen, where
as 2 of 3 patients showed postoperative air leakage which persisted over 5
days. In the hypercapnia group, the maximum PaCO2 during anaesthesia ranged
between 70 mmHg and 135 mmHg (98+/-21 mmHg). During anaesthesia, all 10 pa
tients required inotropic support to prevent hypotension, 1 patients requir
ed tracheal gas insufflation of oxygen to the operated lung to avoid hypoxa
emia and 3 patients required lidocaine to treat ventricular arrhythmia. How
ever, the trachea was extubated in the operation theatre in 9 of 10 patient
s and no organ dysfunction was observed postoperatively. Four patients show
ed postoperative air leak on the first postoperative day, one of which pers
isted over 5 days.
Conclusion: Although there are some limitations, this preliminary study ind
icates that hypercapnia around 100 mmHg during anaesthesia for thoracic sur
gery may not be associated with serious consequences.