Case: Thoracotomy for chronic foreign body removal
11th February 2014
Blowing the entire insurance budget on advanced imaging and leaving nothing left for surgery is not generally a great plan. But in Bella’s case it was an inspired choice on the part of the referring vets and the owners.
Bella, a 3 year old female Springer Spaniel, had had grumbling bouts of pyrexia (high temperature). This was investigated back in September 2013 with a top quality CT scan under the care of one of the very best soft tissue surgeons in the country working at a specialist referral centre. An area of localised pathology was identified in the chest. In a young spaniel this was likely to relate to remnants of plant material that had entered the lungs as a foreign body, and then migrated. Initially the problem was managed medically with apparent success. But when the bouts of pyrexia kept recurring, the advice of the specialist centre was to perform an exploratory thoracotomy (surgical opening of the chest cavity).
Bella’s owners couldn’t afford the surgery to be done at the specialist centre, but they could afford us. We took multiple radiographs of the chest, but even with excellent x-rays it would not have been possible to diagnose the problem. The CT scan had accurately localised the pathology to just behind the heart. So we performed a sternotomy over this area. This involved using a air-powered surgical oscillating saw to neatly cut down the middle of the sternum (breast bone). This approach allowed the chest to be more widely explored than the alternative way of approaching the chest cavity by going between ribs. (You may well have seen sternotomies on TV programs like Holby City as they are widely used in people to access the heart etc!). The sternum at the cranial end (head end) of the sternum was left intact so that the two halves of the rib cage were not completely separate and were not wildly unstable.
These cases require plenty (at least four) experienced staff both during and after surgery. In theatre we used a minimum of one anaestheist and one theatre nurse to assist the anaesthetist and pass kits etc to the surgical team. The surgical team comprised a surgeon and surgical assistant. While the chest cavity was open to the outside, the patient was unable to breath for themselves. So the anaesthetist ventilated the lungs with oxygen (and anaesthetic vapour) by gently and rhythmically compressing a bag. This is called intermittent positive pressure ventilation (IPPV) and this is the key roll in thoractomy procedures. It can be done by ventilator machines, but we prefer IPPV to be done by a person! We use multi-parameter patient monitoring in both of our operating theatres and in our prep-room. Oxygen levels in the peripheral circulation, expired carbon dioxide levels, heart rate and electrical activity, blood pressure and body temperature were all kept under close scrutiny. While the monitoring equipment is a great aid, it is secondary in importance to having an experienced anaesthetist using the prototype mark one eyeball!
The diseased tissue was dissected free of attachments to the lungs and to the heart. A chest drain was placed. This comprised a plastic tube with holes cut into one end of it, passing out through the chest wall between the ribs, and terminating in a valve which would later allow a syringe to be attached. The chest cavity was closed with the aid of wire sutures placed through holes drilled in the sternebrae (the individual bones of the sternum). Once the chest was sealed, air could be drawn out of the chest cavity using the chest drain and valve to re-inflate the lungs. The anaesthetist then closely scrutinised the patient’s ability to breath for themselves and gave further ventilation assistance as required.
Suction was applied to the drain at intervals post-operatively to ensure that there were no accumulations of fluid or air in the chest cavity. Bella was kept under close supervision in the post-operative period until the point of discharge, including through the night. Complications with chest drains can be dealt with, but problems with the chest drain are likely to involve the lungs rapidly collapsing, and if this isn’t spotted as it develops, the consequences can be catastrophic. As well as monitoring the chest drain, close supervision post-operatively is required for providing pain relief. Sternotomies are widely regarded as being painful procedures so multi-modal analgesia (hitting the pain with everything in our arsenal) was employed. We used local anaesthetics, methadone, non-steroidal anti-inflammatory drugs (NSAIDs), ketamine, alpha-2 agonists in the anaesthetic plan, and we used local anaesthetics (infused down the chest drain tube), methadone and NSAIDs post-op.
Bella was unbelievably bright and comfortable within hours of surgery, and it was all we could do to stop her leaping out of her cage and dragging us around on her lead when taken out for a toilet break. In Bella’s case, early removal of the chest drain was possible as early as 12 hours post-operatively once we were sure that it was no longer needed. Bella was discharged about 30 hours post-operatively, on oral medication. Her owner kept us informed and reported that she had a very comfortable convalescence.
The lab analysed the excised samples and reported that the tissue samples contained chronic inflammation centred around remnants of plant material. As suspected, this will have been a foreign body that had tracked through lung tissue into the chest cavity.
The future looks bright for Bella, but we’ll have to see whether any further pyrexic episodes develop in the future. We will only ever remove the wire sutures if they cause issues. Otherwise they are there for keeps!