Small-Caliber Endoscopy

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Chapter 10 Small-Caliber Endoscopy

Christopher J. Gostout

Introduction

Small-caliber endoscopy has selective appeal. Sedation may be responsible for a substantial proportion of the morbidity and mortality of endoscopic procedures. The opportunity to perform diagnostic endoscopy without sedation can overcome the issues relative to sedation, especially in high-risk patients. The administration of sedatives increases the preprocedure preparation, total procedure, and postprocedure recovery times. Finally, the “sedationless” argument gains strength with regard to lifestyle impact, allowing the patient to minimize time away from work or family and eliminating the need for an accompanying responsible person. Despite its potential safety and cost-effectiveness, however, the practice of unsedated endoscopy with small-caliber endoscopes has not gained wide acceptance. Many factors may be responsible, including inadequate evidence for efficacy, poor patient acceptance, lack of physician incentives, and limited opportunities for training.

Small-caliber endoscopy has other practical uses. Patients who may be predictably intolerant of endoscopy with sedation, such as young patients, are potential candidates for this option. Small-caliber endoscopy offers a dramatically reduced procedure stress for patients who have fragile cardiopulmonary disease. The small-caliber endoscope provides an effective and well-tolerated option for the placement of transnasal feeding tubes and the placement of jejunal extensions via an existing percutaneous feeding gastroscopy site.¹^–³ Patients with high-grade esophageal strictures with existing percutaneous feeding gastrostomy may have primary or rendezvous attempts at dilation with placement of guidewires using a small-caliber endoscope via the gastrostomy site.^4,⁵

Small-Caliber Endoscopy Insertion Techniques

Small-caliber upper endoscopy can be performed either transnasally or perorally (Fig. 10.1). Transnasal endoscopy is feasible with endoscopes measuring 6 mm or less in outside diameter. Table 10.1 summarizes specifications of small-caliber endoscopes used in the reviewed studies and other endoscopes that are commercially available. Both videoesophagogastroduodenoscopes and esophagoscopes are currently available. Videoesophagogastroduodenoscopes have a working length of 1030 to 1330 mm, and esophagoscopes have a working length of only 600 mm. The outer diameter of videoesophagogastroduodenoscopes is between 5.1 mm and 6 mm. Esophagoscopes have an outside diameter between 3.1 mm and 4 mm. The relative outside diameters of small-caliber pediatric and conventional esophagogastroduodenoscopes are shown in Fig. 10.2A. Some esophagogastroduodenoscopes allow right and left and up and down angulation, whereas others provide only up and down angulation (Fig. 10.2B).

Fig. 10.1 Nasal passage anatomy. Small-caliber endoscope is passed directly back along the floor of the nasal passage, along the medial septum, avoiding the turbinates, with flexion of the tip down into the posterior pharynx (line arrow).

Table 10.1 Fiberoptic and Video Small-Caliber Endoscopes Available for Unsedated Upper Endoscopy

Fig. 10.2 Small-caliber upper endoscopes. Distal ends of a small-caliber, pediatric, and conventional esophagogastroduodenoscope are shown (A) along with the handle of a small-caliber endoscope with only one ratchet for up and down control (B).

Careful patient selection and preparation are of utmost importance. Uncooperative patients and young patients with a high preprocedure anxiety level are not well suited for unsedated procedures. Elderly patients tolerate the examination extremely well—so well that in our institution we contemplated offering this exclusively for patients 80 years or older undergoing diagnostic endoscopy. Because the tolerability of the procedure is related to preprocedure anxiety, the procedure must be explained clearly before intubation.

Topical anesthesia in the form of a spray or jelly is useful before endoscope insertion. The application of 2% lidocaine jelly into the more patent nostril as determined by visual inspection is recommended for this approach to topical anesthesia. Pharyngeal anesthesia is also recommended. Local vasoconstrictors may also be beneficial, especially when a 6-mm diameter instrument is inserted transnasally. If a 4-mm or smaller caliber endoscope is used, a local vasoconstrictor may be of marginal value to aid insertion, but it may minimize epistaxis.

The procedure can be performed either in the standard left lateral decubitus position for conventional endoscopy or in the upright position (Fig. 10.3). Whether the upright position decreases the aspiration risk is unknown. The transnasal procedure should be performed with minimal air insufflation. The endoscope should be inserted slowly and gently, keeping the insertion tube of the endoscope straight such that it passes along the floor and septum of the nasal cavity and it does not migrate upward and laterally into turbinates interrupting passage, causing pain, and inducing bleeding. Slow progressive insertion with flexion of the endoscope tip over the base of the tongue is recommended for unsedated peroral examinations. Vigorous movements of the endoscope cause greater nasal discomfort with the transnasal route and more gagging with the peroral approach. During the procedure, conversing with the patient and pointing out findings on the video monitor reassure patients and may improve tolerability and reduce discomfort.

Fig. 10.3 Patient is shown undergoing transnasal small-caliber esophagogastroduodenoscopy in the upright position.

Unsedated Small-Caliber Upper Endoscopy

The impact of unsedated small-caliber endoscopy on the everyday practice of esophagogastroduodenoscopy (EGD) is complex. There are no data from large randomized controlled trials. Although lower procedure cost and complication rate favor unsedated EGD, poor patient tolerance, suboptimal visualization, and failure to complete the procedure could increase the cost of upper endoscopy secondary to repeated examination by sedated EGD. Analyses of the few existing randomized controlled studies provide sufficient evidence that unsedated small-caliber upper endoscopy is feasible and tolerable in select patient groups. Most evidence suggests, however, that small-caliber endoscopy is slightly less sensitive.

There are conflicting reports regarding the transnasal approach and whether or not it is preferred over the peroral route. Based on a questionnaire provided to patients undergoing endoscopy at our outpatient units, patient preference is actually for peroral intubation. This preference has been well appreciated within our motility practice, which for decades has performed esophagogastroduodenal motility via a peroral catheter approach. Data are insufficient regarding the safety of unsedated small-caliber endoscopy compared with sedated conventional endoscopy. Finally, the cost-effectiveness of unsedated small-caliber endoscopy is yet to be determined. With that in mind, the following sections summarize the literature addressing the various aspects of unsedated small-caliber endoscopy.

Technical Feasibility of Unsedated Small-Caliber Endoscopy

Feasibility of unsedated small-caliber endoscopy is mainly a subjective measure defined by the endoscopist. It can be affected by many factors, including the diameter of the small-caliber endoscope, endoscope maneuverability, image quality, patient tolerability, and the skills of the endoscopist. Feasibility of unsedated endoscopy is particularly linked to tolerance, which is discussed in the next section. In the crudest sense, technical feasibility represents the successful completion of the intended procedure by intubating the duodenum if an EGD is being performed or intubating the stomach if esophagoscopy is being done. Several investigators have reported the feasibility of transoral or transnasal unsedated EGD.⁶^–¹⁸ Most of these studies have not been prospective randomized controlled trials. The patient populations have been either small in size or not representative of the general U.S. population. Studies addressing the feasibility of EGD that warrant attention are described next.

Wilkins and coworkers ⁶ randomly assigned 72 patients to undergo either unsedated small-caliber EGD or sedated conventional EGD. Despite a highly selected and motivated U.S. Air Force community population, only 29 of the 33 patients (88%) had a complete unsedated small-caliber EGD. In another controlled study, Mulcahy and coworkers⁷ compared the feasibility of unsedated small-caliber EGD with unsedated conventional EGD in 322 patients. EGD was completed in 160 of the 163 patients (98%) undergoing unsedated EGD with a 6-mm gastroscope compared with 145 of the 159 patients (91%) undergoing unsedated EGD with a 9.8-mm gastroscope. These investigators subsequently reported 39 (8%) failures in a prospective study of 508 patients undergoing routine unsedated gastroscopy.⁸ Failure was associated with larger scope diameter (>9 mm), higher preprocedure anxiety, and younger age.

Ristikankare and colleagues ⁹ randomly assigned 180 patients undergoing EGD to receive intravenous (IV) midazolam, IV saline, or no IV access. Although the procedure was perceived “less difficult” in the IV midazolam group compared with the IV saline group, the difference was not statistically significant. The power to detect differences between the three groups was not determined in this study. The small patient population and the lack of validated criteria to assess the difficulty of an EGD limit the utility of the evidence.

The feasibility of unsedated small-caliber EGD was also assessed as part of the multiphase Mayo Clinic Rochester study of a select group of highly motivated patients and volunteers.¹⁰ The second portion of the duodenum was reached in 20 sedated and 20 unsedated volunteers in this prospective, nonrandomized study. Among the patients, 50 subjects successfully underwent sedated small-caliber EGD followed by sedated conventional EGD, and 38 of 40 patients underwent successful unsedated small-caliber EGD followed by sedated conventional EGD. Overall, the technical feasibility was not significantly affected by sedation in this study. A type II error (failure to detect a significant difference when there is a difference) cannot be ruled out, however, because the sample size to detect a significant difference was not calculated.

Investigators have also studied the feasibility of unsedated transnasal small-caliber EGD. Saeian and coworkers ¹¹ showed that unsedated transnasal esophagoscopy with a 5.3-mm gastroscope was feasible in 15 cirrhotic patients. The study was uncontrolled, and the population was very small. Zaman and colleagues¹³ compared peroral and transnasal approaches for EGD with the same small-caliber instrument using a prospective randomized crossover study design. Of 105 patients, 60 (57%) agreed to undergo unsedated small-caliber EGD. Peroral unsedated EGD was feasible in 34 of 35 (97%) patients, including 4 who failed transnasal EGD and were crossed over. Unsedated transnasal EGD was feasible in only 25 of 29 (86%) patients. The statistics were not reported, and a sample size based on a study hypothesis was also not calculated before study initiation.

Campo and coworkers ¹⁴ randomly assigned 181 Spanish patients to undergo transnasal small-caliber EGD or peroral conventional EGD. Insertion failed in six (3.3%) patients; four had been randomly assigned to the transnasal route and two to the peroral route. In a prospective randomized trial in Australia, Craig and colleagues¹⁷ compared the feasibility of unsedated transnasal with unsedated peroral small-caliber EGD. A complete examination was feasible in 74 of the 84 (88%) transnasal and 85 of the 86 (99%) transoral procedures (P = .004).

Dumortier and coworkers ¹⁸ reported that unsedated transnasal EGD was feasible in 1033 of 1100 (94%) patients studied prospectively at three French medical centers. Failures were mainly due to the inability to insert the small-caliber endoscope (62.7%). Other reasons for failure included patient refusal and nasal pain. In their prior study published in 1999, the same investigators showed that unsedated transnasal EGD was feasible in 82% of the study population and was associated with less nausea and choking.¹⁹ The feasibility of transnasal small-caliber EGD was initially assessed in 100 patients in this two-phase study; 150 patients were then randomly assigned to undergo peroral conventional EGD with a 9.8-mm videoendoscope, peroral small-caliber EGD with a 6-mm videoendoscope, or transnasal small-caliber EGD with a 6-mm videoendoscope.

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