Complications after thoracic surgery: don't (necessarily) blame it on the approach
Article first published online: 27 MAY 2013
© 2013 British Small Animal Veterinary Association
Journal of Small Animal Practice
Volume 54, Issue 6, pages 283–284, June 2013
How to Cite
Chanoit, G. (2013), Complications after thoracic surgery: don't (necessarily) blame it on the approach. Journal of Small Animal Practice, 54: 283–284. doi: 10.1111/jsap.12089
- Issue published online: 27 MAY 2013
- Article first published online: 27 MAY 2013
In this issue of JSAP, Meakin et al. (2013) report the results of a retrospective study looking at risk factors associated with intrathoracic infection (pyothorax) following thoracic surgery. One of the major findings of their study is that the risk of postoperative pyothorax is significantly increased in dogs treated for chylothorax. The fact that the presence of pleural effusion, the presence of chest drains, and the history of previous (multiple) thoracocentesis were all potential risk factors for the development of pyothorax can obviously explain this result. However, interestingly, the surgical approach in all the dogs with chylothorax in this study was via a median sternotomy.
Although the authors have emphasized in their discussion that the occurrence of pyothorax following thoracic surgery is likely multifactorial and does not incriminate only the surgical approach, I am fairly convinced that after reading this study, a few surgeons (including myself probably) will think twice before approaching the chest via a median sternotomy when treating a dog with chylothorax. Rightly or wrongly, median sternotomy is already an unpopular chest approach even though sternums have been cut longitudinally (or even transversally) since the time experimental dogs were paying a large contribution to advances in thoracic procedures (Andreasen & Watson 1953).
It is interesting to note that median sternotomy was critically evaluated in clinical peer-reviewed studies (Bright et al. 1983, Burton & White 1996), much earlier than lateral thoracotomy (Moores et al. 2007). Clearly, in the veterinary surgeon's mind, there has always been a large difference between these two techniques. However, when comparing results, one needs to remember that these studies are not contemporaneous and many aspects of veterinary surgery and postoperative care have positively evolved between the early 1980s and the late 2000s.
Evaluating the complications and morbidity (let alone mortality) associated with different approaches to the thoracic cavity is a very complicated task unless one can evaluate the same condition (e.g. lung tumours, coronary by-pass) and compare the approaches. Similar studies in humans show that median sternotomy is not associated with an increase in wound infection and probably not associated with an increased level of postoperative pain compared to a lateral thoracotomy (Asaph et al. 2000, Rogers et al. 2012). The conformation of the chest in dogs is different than in humans and we should probably not directly compare results. Yet it is clear from the human literature that sternotomy is no longer considered as daunting an approach compared to 20 or 30 years ago when large sample studies and meta-analysis were not available to increase the level of evidence.
Some veterinary studies have incriminated the thoracic approach to explain the outcome of one particular condition (e.g. pyothorax) suggesting that the high complication rate following surgical treatment of pyothorax is due, in part, to the approach taken (namely the median sternotomy) rather than simply the results of the underlying pathology. This is probably partially true but the chances are that if you are going to surgically treat a pyothorax, you will need to enter the chest via a median sternotomy (until we can prove that we can obtain the same results via keyhole approaches) as you probably gain better exposure and are more efficacious than by using a lateral approach. Thus it may be hazardous to neglect the right to a sternotomy based on presumptions.
Tattersall & Welsh (2006) rightly stated that “…prospective studies are required to fully evaluate the true effect of the thoracotomy approach on postoperative wound complications…”. Such studies are still lacking in the veterinary literature.
So how can we minimize postoperative complications after thoracic approaches, especially if we assume that the complication rate varies greatly between techniques?
As infection is a potential complication after sternotomy, would a change in closure techniques be a reasonable measure to evaluate critically? The common belief is that we should use wire to close a sternotomy (Pelsue et al. 2002). However, monofilament suturing of the sternum is common in human surgery (Luciani et al. 2006) and appears biomechanically equivalent to wiring (Gines et al. 2011). There is clearly a need to look prospectively at these methods in veterinary patients.
The effect of chest approach on postoperative pain (one other major complication after thoracic surgery) should also be a topic of critical appraisal. There is no veterinary study comparing the degree of pain following sternotomy and thoracotomy even if we know that some methods of chest closure can potentially lead to a lower level of postoperative pain (Rooney et al. 2004). To minimize pain it would seem logical to continue the trend towards keyhole approaches. Thoracoscopy has become the preferred method to evaluate the chest fully, to take biopsies (Schmiedt 2009) and for some procedures such as pericardiectomy (Dupre et al. 2001). Certainly, some studies tend to report a favourable outcome of thoracic procedures done via minimal access approaches in terms of pain control. Yet reported measurable outcomes, such as reduced hospital stay, at the moment do not necessarily completely support the superiority of this method over the standard method (Lansdowne et al. 2005).
Let's not forget that the evidence that key-hole thoracic surgery in small animals results in less pain than the open approach remains weak. The only study that has critically compared the level of pain following these two different approaches was done on healthy dogs and used cortisol and blood glucose concentrations to assess the degree of postoperative pain (Walsh et al. 1999); these outcome measures are not considered very robust to evaluate acute pain in animals (Lascelles 2012). In human prospective case-matched studies, results have shown no difference in terms of chronic pain post thoracoscopy versus thoracotomy (Furrer et al. 1997).
Logically, animals that are operated via key-hole procedures should feel less pain and be more active postoperatively than the ones operated via large incisions (especially when they involve cracking through bone!). Yet although evidence exists that a minimal access approach is better than a standard open approach for abdominal procedures (Culp et al. 2009), further studies are needed in thoracic surgery.
Ultimately, no matter how efficient and meaningful (i.e. resulting in less pain and complications than an open approach) veterinary thoracoscopy proves to be in the future, there will always be a need for open approaches (even if we call them mini-thoracotomy or mini-sternotomy). Therefore, can we potentially refine the method of chest wall retraction to decrease postoperative pain? In one unpublished but already web-based advertised study (Zimmer 2011), a significant reduction in forces needed to maintain a predefined retraction of the chest wall if a “smart” retractor was used instead of the standard Finochietto retractor (rib spreader) has been demonstrated. The smart retractor is able to sense the forces on the muscles and ribs, thereby adjusting the retraction forces rather than non-specifically forcing retraction. As a consequence, acute pain post thoracotomy was lessened and respiratory function in the immediate postoperative period was improved. This type of retractor will certainly be of tremendous help in human thoracic surgery if it decreases the occurrence of chronic post thoracotomy pain syndromes. Would that be relevant to veterinary thoracic surgery?
There may be a need to think about how we can improve further our success and decrease the complication rate in thoracic surgery not only by rethinking and improving how we perform procedures in the chest but also by how we get in and out of it.
- 1953) Experimental thoracic surgery in dogs. Annals of the Royal College of Surgeons of England 12, 261–274 & (
- 2000) Median sternotomy versus thoracotomy to resect primary lung cancer: analysis of 815 cases. The Annals of Thoracic Surgery 70, 373–379 , , , et al. (
- 1983) Clinical and radiographic evaluation of a median sternotomy technique in the dog. Veterinary Surgery: VS 12, 13–19 , , , et al. (
- 1996) Review of the technique and complications of median sternotomy in the dog and cat. The Journal of small animal practice 37, 516–522 & (
- 2009) The effect of laparoscopic versus open ovariectomy on postsurgical activity in small dogs. Veterinary Surgery: VS 38, 811–817 , & (
- 2001) Thoracoscopic pericardectomy performed without pulmonary exclusion in 9 dogs. Veterinary Surgery: VS 30, 21–27 , & (
- 1997) Thoracotomy and thoracoscopy: postoperative pulmonary function, pain and chest wall complaints. European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery 12, 82–87 , , , et al. (
- 2011) Mechanical comparison of median sternotomy closure in dogs using polydioxanone and wire sutures. The Journal of Small Animal Practice 52, 582–586 , , , et al. (
- 2005) Thoracoscopic lung lobectomy for treatment of lung tumors in dogs. Veterinary Surgery: VS 34, 530–535 , , , et al. (
- 2012) Surgical pain: pathophysiolgy, assessment, and treatment strategies. In: Veterinary Surgery: Small Animal. Eds K. M. Tobias and S. A. Johnston. Elsevier, St. Louis, MO, USA. p244 . (
- 2006) Adjusting the indication to polydioxane suture for elective sternal closure. The Journal of Thoracic and Cardiovascular Surgery 132, 1243–1244; author reply 1244 , & . (
- 2013) Prevalence, outcome and risk factors for postoperative pyothorax in 232 dogs undergoing thoracic surgery. The Journal of Small Animal Practice , , , et al. (
- 2007) Indications, outcomes and complications following lateral thoracotomy in dogs and cats. The Journal of Small Animal Practice 48, 695–698 , , , et al. (
- 2002) Closure of median sternotomy in dogs: suture versus wire. Journal of the American Animal Hospital Association 38, 569–576 , , , et al. (
- 2012) An open randomized controlled trial of median sternotomy versus anterolateral left thoracotomy on morbidity and health care resource use in patients having off-pump coronary artery bypass surgery: The Sternotomy Versus Thoracotomy (STET) trial. The Journal of thoracic and cardiovascular surgery DOI: pii:S0022-5223(12)00861-6. 10.1016/j.jtcvs.2012.04.020. [Epub ahead of print] , , ., et al. (
- 2004) Intercostal thoracotomy closure: transcostal sutures as a less painful alternative to circumcostal suture placement. Veterinary Surgery: VS 33, 209–213 , & (
- 2009) Small animal exploratory thoracoscopy. The Veterinary Clinics of North America. Small Animal Practice 39, 953–964 (
- 1999) Thoracoscopic versus open partial pericardectomy in dogs: comparison of postoperative pain and morbidity. Veterinary Surgery: VS 28, 472–479 , , , et al. (
- 2011) Turning to biomechanics to build a kinder, gentler rib spreader. In: Sciences. The New York Times (
Guillaume Chanoit graduated from the Veterinary School of Toulouse, France. After holding academic positions in France and in the United States, Guillaume came to the UK in 2011, taking up the position of Senior Lecturer in Small Animal Soft Tissue Surgery at the University of Bristol. He is also a member of the Bristol Heart Institute where he undertakes a large portion of his research. Guillaume has a particular interest in cardiothoracic surgery. He is a JSAP Associate Editor for soft tissue surgery.