It has already been emphasized that the colonoscopy completion rate is important for more than just academic reasons [8] and one important reason is that a completed colonoscopy reduces the likelihood of an advanced colorectal-cancer being detected later on [16].
In this report on a single centre's experience of colonoscopies systematically associated with deep sedation with propofol, the global success rate achieved by 21 endoscopists working at the same endoscopic centre with different levels of expertise and training was 93%.
The factors negatively influencing the success of the test were: a patient's small body size, age over 71 years, inadequate colonic cleansing and the need for AAI during deep sedation. For the purposes of this study, we did not correct the performance rate by excluding colonoscopies in which cecal intubation had been prevented by the presence of faecal material, because our aim was to establish the crude success rate for colonoscopy under deep sedation. It is worth adding here that more tests were interrupted due to poor cleansing issues when less expert endoscopists were involved.
Two complications of endoscopy (one perforation and one post-polypectomy haemorrhage) were recorded during the study period, a prevalence similar to that of other reports [17]. We used a broad definition of "adverse events" during colonoscopy under deep sedation, recording all action taken by the anaesthetist to restore adequate oxygenation or hemodynamics, even for short-lived monitoring problems, because such situations might influence the procedure or have to do with longer probe insertion times necessitating further propofol infusions. No hemodynamic resuscitation was needed and there were no major clinical sequelae after sedation.
One of the limits of this study is that we were not in a position to compare how different colonoscopic methods might improve the colonoscopy completion rate.
Although ours was an observational study on the controversial issue of the routine use of deep sedation for colonoscopies, it had the advantage of referring to a recognized target (i.e. 95% cecal intubations in colonoscopies for screening purposes). Other published series adopted a different approach, achieving a different gap between their results and the 95% target [18–20].
The performance measurement showed that the endoscopist's skill influences the success of colonoscopies even when deep sedation is used. In a clinical setting, this poses problems that have already been studied and overcome using quality improvement programs and auditing cycles [11]. All our endoscopists had gained experience during weekly sessions for more than a year, implementing 200 procedures alone (a number recognized as being sufficient to achieve a satisfactory performance in screening programs)[21]. When it comes to screening programs, the endoscopists' different levels of experience carry a different weight from the situation in routine clinical practice because the most important problem is often the shortage of operators. Solutions have to be found to deal with the problems of the burden of colonoscopies to perform and increasingly long waiting lists, which is why colonoscopies may be performed by gastroenterologists, clinical assistants, trainee gastroenterologists or nurses in some countries [22].
The aim of our study, however, was to ascertain whether using propofol sedation enables the standard to be reached in screening programs, when it is necessary to employ many endoscopists who are likely to have different levels of expertise.
Success rate has been seen as an expression of "technical machismo" [8] and some authors suggest that it should not be influenced by patient-related factors and that, in any case, a trained endoscopist should be able to complete 95% of colonoscopies successfully [23]. We considered it important to demonstrate that patients' weight and age, as already mentioned in other studies [24, 25] without deep sedation, are factors that also predict incomplete colonoscopies among series of colonoscopies performed under deep sedation at a busy teaching hospital service, where endoscopists of different abilities are at work.
Different strategies can be used to improve the quality of colonoscopic screening programs. We chose to consider the role of routine deep sedation. Propofol was preferred as a sedative because previous observational studies using other drugs for sedation during colonoscopy in almost 94% of the sample had still reported unacceptably low success rates [26]. In addition, it has recently been demonstrated that deep sedation enhances the polyps detection rate [27].
A weakness of our study is that we did not perform a thorough cost-benefit analysis, particularly as concerns the need for extra personnel to manage sedation. This issue depends largely on differences in the compensation awarded by national health systems and on their related organizational aspects, but relevant data could probably be obtained quite easily by adapting our findings to different situations in different countries. We also collected no details on patients' satisfaction with the procedure, because this information is only collected at our centre in the context of clinical trials and we wished to avoid any Hawthorne effect on the endoscopists' routine practice.
Our study has shown a possible strategy for further improving the rate of successful cecal intubations, i.e. by modifying certain organizational aspects when deep sedation is used.
If a "difficult patient" (aged over 71 and weighing less than 60 kg) has to undergo colonoscopy at the hands of a "less experienced non-specialist" (instead of a "highly experienced specialist"), then inadequate colon preparation reduces the chances of the colonoscopy being completed by 70%. So, special attention should be paid to colon-cleansing practices for colonoscopies that are to be handled by a less experienced endoscopist. Moreover, if any unwanted effects of propofol infusion demanding AAI can be avoided by a careful management of sedation, then 60% of incomplete procedures could be successful. In other words, if a difficult colonoscopy is programmed (due to the patient's characteristics), then containing the need for AAI and improving bowel cleansing enables the successful completion of 90% of incomplete colonoscopies whatever the expertise of the endoscopist involved.