To our knowledge, this is the first published controlled randomised study evaluating efficiency, training effect, and safety of tube thoracostomy, comparing kits equipped with either blunt or sharp tips in a sample of human cadavers.
Chest thoracostomy using sharp tipped trocars was around 4 seconds faster than using blunt tips; however, this difference seems to be clinically not relevant. Insertion times were increased in obese cadavers, operator related, and could be reduced with training. Using either kit led to high complication rates, with a significantly increased incidence of organ injuries using sharp tipped as compared to blunt tipped trocars.
In 2009, the National Patient Safety Agency in the United Kingdom reported that equipment problems, adequate training, and site selection are crucial factors influencing effective and safe chest drain insertion . Pleural drainage techniques are not uncomplicated, and have the potential to cause life-threatening injury . Even though there is ongoing debate about its safety, the sharp tipped chest trocar technique is still widely used [8, 21, 22]. A recent study by Dural et al. reports higher success rates without difference in complication rate using a sharp tipped trocar when compared to a surgical technique in human patients . In this study, the usual trocar technique was modified such that the pleural space and adhesions were bluntly dissected with a finger before advancing the thoracic trocar and drain. In other words, the trocar was not used to dissect, but to guide the drain into the pleural space. This technique is comparable to the one described in this report. Rates of misplacement or ineffective drainage for these trained cardiothoracic surgeons were reported to be 13.3% with the surgical technique and 7.8% with the trocar technique . The authors used a kit similar to kit 2 described in this study, which in our training regime resulted in a high complication rate of 14% overall. Nevertheless, although our complication rate was higher than that reported by Dural et al., it is perhaps not surprising if one considers the relative lack of experience of the physicians that participated in our study, compared to that of trained surgeons that participated in the study of Dural. However, the Early Management of Severe Trauma (EMST)/Advanced Trauma Life Support (ATLS) courses and current guidelines still advocate the non-trocar technique as a safer method of chest tube insertion. The comparable high complication rates observed in our study consequently do not give an indication to change that policy and refute the findings by Dural et al claiming the trocar technique being equally safe.
Although smaller tubes are (< 14 F) increasingly used , we evaluated the use of medium sized bore tubes (24 F), as they are recommended for managing hematothorax, mechanical ventilation barotrauma, and some cases of pneumothorax .
In our study, surprisingly, no relevant difference in thoracostomy insertion time between kits could be demonstrated with a sample size of 100 trials in each group. Our sample size was set randomly, without a pilot study to establish the power of this study. By increasing its sample size the probability to reject the null hypothesis could have been increased. However, we believe that our results reliably demonstrate that there is no clinically relevant difference in insertion efficiency between the kits. Interestingly, from first to fifth attempt, time for insertion could be significantly reduced by 20 seconds, indicating a training effect. Using human cadavers as a teaching model, Proano et al. demonstrated significant reductions in insertion times : Average time for first insertion attempt was 86 seconds, which decreased to 34 seconds at the fourth attempt. This strong training effect may be explained by the fact that trainees performed four procedures in a row in the same session. In our setting, by contrast, each thoracostomy was performed in one month intervals. So even though mean values slightly differ between studies, our results confirm a training effect and emphasise the usefulness of this training model.
In our study, insertion time was increased in cadavers with higher BMI, demonstrating that obesity impedes chest tube insertion. No association between increased BMI and tube malposition could be found, which is in accordance with findings reported in critically ill patients . However, in both studies the correlation of BMI and chest tube malposition has been reported as a secondary outcome and was not sufficiently powered to draw a definite conclusion.
The use of human cadavers for chest tube insertion is a well-established method for training purposes . There are, however, several limitations. The condition of the somatic tissue present in the cadaveric state is significantly different from that found in the living human. Furthermore, complications, such as bleeding of an intercostal artery, infections, and problems arising with chest tube removal cannot be simulated. Despite these limitations, we could demonstrate that misplacement or organ injury occurs significantly more frequently using sharp tipped trocars. We taught trainees to insert the chest tubes via the fourth or fifth intercostal space in the mid-axillary line because the diaphragm may rise to the level of the fourth intercostal space during full expiration. However, as described above, misplacements and organ injuries occurred mainly because chest tubes were placed via the seventh or eighth intercostal space. This confirms the conclusion by Lamont et al. that difficulties in identifying intercostal structures impede correct placement .
Interestingly, even though all participants had the same level of training, misplacement was operator related, and not related to number of prior training sessions. This shows that training duration may need to be customised to the individual trainee's learning rate. Cadaveric simulation may be an effective device to identify individuals that may benefit from additional training. Furthermore, it emphasises general recommendations that adequate training is a primary influence on the incidence of chest tube complications [26, 27].
One might be surprised about the low level of experience in inserting chest drains of emergency physicians with at least 2 years of training. In our study center, the General Hospital of Vienna (AKH-Wien, Vienna, Austria), emergency care is divided into a medical emergency department and a trauma emergency department. Our physicians were recruited entirely from the medical department, as we believed training effects could be better demonstrated with physicians with little surgical training.