The use of intrabronchial valves may have implications for anaesthetists. A 67-year-old woman with severe emphysema was assessed in our consultant-led preoperative vascular anaesthesia clinic to assess fitness for endovascular repair of an abdominal aortic aneurysm (EVAR). The patient had recently entered a blinded randomized control trial investigating the utility of intrabronchial valves as a symptomatic treatment for severe emphysema. She had recently undergone bronchoscopy under general anaesthesia and had been randomized to the treatment arm, having had seven valves inserted.
Intrabronchial valves (IBV valve; Spiration Inc., Redmond, Washington, USA) were originally developed for use in patients with prolonged air leaks after lung volume reduction surgery and have approval for use in this respect. They are now being investigated as a less invasive alternative in the general management of severe emphysema. Over 200 patients in the USA have received intrabronchial valves, but our patient was one of the first UK patients. We knew very little about the device and the implications for anaesthesia. We gathered information from various sources including the manufacturer and clinicians involved in trials both in the UK and the USA.
The IBV valve is a self-expanding umbrella-shaped device that is implanted bronchoscopically under general anaesthesia. Valve diameter sizes vary between 4 and 7 mm. It is designed to obstruct airflow to targeted segments causing diversion of airflow away from emphasematous lung while still allowing passage of air and mucus back past the device. The mechanisms of action are thought to be an improvement in ventilation/perfusion, atelectasis of lung bullae and a decrease in dynamic hyperinflation. Initial results from the multicentre US trial suggest a statistically significant improvement in health-related quality of life.1 Results of resting spirometry do not correlate with symptomatic improvement and are not felt to be a useful tool when judging the efficacy of this treatment, probably because lung volume reduction behind the valves will be balanced by increases in lung volume in healthier parts of the lung.
Our patient had had emphysema for 20 years, was receiving maximal medical therapy including home oxygen for exertion and had an exercise tolerance of 200 yards. She would usually consume 300 l of oxygen every 2 weeks. Four months after insertion of the valves (patient now no longer blinded to trial), she reported an improvement in her daily symptoms and had noticed her 300 l of oxygen was now lasting up to 5 weeks. Her lung function tests did not show significant improvement.
The incidence or nature of complications associated with general anaesthesia and these valves is unknown and there are no published case reports. We were concerned about the possibility of valve dislodgement or displacement secondary to positive pressure ventilation, endobronchial suctioning, coughing or straining on an endotracheal tube. What was the risk of tension pneumothorax and perioperative bronchospasm? After discussion with the manufacturers and the chest physician involved in the UK trial, we decided that preoperative removal of the valves would not be beneficial because this would require another intervention under anaesthesia and a probable deterioration in symptoms. On questioning, the patient did not want them removed because of the benefit she was experiencing.
The infrarenal aortic aneurysm was amenable to repair using a standard endovascular approach via the femoral arteries allowing us to avoid general anaesthesia in favour of a regional technique. We successfully used a combined spinal/epidural technique and the patient had an uneventful postoperative recovery with no respiratory complications.
There are currently very few patients worldwide with intrabronchial valves in situ, but, with more clinical trials currently underway, these numbers will increase. The early positive results from the US trial and the increasing incidence of emphysema suggests that these devices will become more commonplace in the future and will be more frequently encountered by anaesthetists. On balance, we feel that the use of positive pressure ventilation is likely to be well tolerated and acceptable, but anaesthetists should be vigilant to changes in airway compliance and have a high index of suspicion should problems arise. We are sure that any patient with severe emphysema would always be offered a regional anaesthetic as first choice if feasible. Fortunately, the advent of EVAR allowed for a safer anaesthetic approach.
References
1 Wood DE, McKenna RJ Jr, Yusen RD,
et al. A multicenter trial of an intrabronchial valve for treatment of severe emphysema. J Thorac Cardiovasc Surg 2007; 133:65–73.
