Four Handed Intubation Technique – Part 2
6. How to manage the patient
During the colonoscopy, the patient has to be rotated in the most favorable position to engage each colonic segment, on the bass of colonic morphology. The position of the patient on the table should be changed according to the steps of the procedure and the segment to intubate. Also during withdrawal it may be useful to examine the same segment in two different postures to achieve ideal visualization of the mucosa. At the beginning of colonoscopy the patients is in the left lateral decubitus, both in the 2-hands and 4-hands tchniques (Fig. 21).
Fig. 21: the position of the patient on the table is in the left lateral decubitus at the beginning of the endoscopic procedure
Although the colonoscopy can sometimes be completed without changing the position of the patient, it is usually convenient to change his/her position to ease the compression of the patient’s abdomen by the nurse in case of troubles in the advancement of the scope (Fig. 22).
Fig. 22: during the intubation it may be useful to place the patient in supine position to facilitate progression of the scope. This also makes the abdominal compression easier.
In the 4-hands technique, in the absence of anatomical abnormalities of the colon, the patient is generally rotated in supine position soon after passing the splenic flexure and up to cecum (Fig. 23 B). In such position, in fact, it is easier for the nurse to exert compression on the abdomen. Furthermore, in case of a ptosic transverse colon, the prone position makes the “stiffening” of the colonoscope more effective, also supported by the manual compression.
When the colonoscope is engaged in the transverse colon and the progression is particularly hard, the patients can be rotated in the right decubitus (Fig. 23 C): due to the gravity, the transverse colon slides on the right side of the abdomen and this attenuates both the angle of the splenic flexure and the overall curvature of the transverse colon, facilitating the advancement of the colonoscope. Particular shapes of the colon may require frequent changes in the position of the patient to ease progression by avoiding “parasite” bending of the instrument (Fig. 23 A-D).
Fig. 23 A-D: the different positions of the patient on the table (A left decubitus, B supine, C right decubitus, D prone) should be selected by the endoscopist in order to facilitate the progression of the colonoscope without forming excessive bends or loops.
7. How to best use the angling functions of the colonoscope
During the intubation, while the nurse tunes the insertion of the colonoscope, the endoscopist “anticipates” the curvatures of the sigmoid colon, the splenic flexure and the hepatic flexure with the left-right control knobs. Unlike to 2-hands technique where the endoscopist directly controls torque and rotation of the scope (Fig. 24) and does not use the left-right angulation, in the 4-hands technique the left-right angulation is essential to pass the recto-sigmoid junction, the splenic flexure and the hepatic flexure.
Fig. 24: in the 2-hands technique the endoscopist operates rotations and torque of the colonoscope with the right hand
During insertion, the up-down tip deflection is calibrated with the thumb of the left hand a (Fig. 25 A) to keep the center of the lumen, while the right hand operates the left-right turn according to the segment to be passed (Fig. 25 B).
Fig. 25 A-B: the thumb of the left hand maneuvers the 'up-down' angulation to keep the tip of the scope at the center of the lumen (A); the fingers of the right hand apply the necessary degree of angulation to pass the bend in specific points.
If the colonoscope is constantly straight, the recto-sigmoid junction (which appears on the right side of the endoscopic view with the patient in left lateral decubitus) is passed turning to the right the left-right control knob as soon as the tip of the scope arrives to the apex of the colon bend without crossing it. In this way the angle of the curve between rectum and sigmoid is partially “flattened” and the segment of the colonoscope past the angling tract slides forward. Then the chest is rotated on the right, thus imparting a right torsion to the instrument that “leans against” the curve between rectum and sigmoid and makes effective the push toward the sigmoid-descending junction which is usually passed moving upward the “up-down” control knob. When passing the recto-sigmoid junction the tip of the scope will be angled on the right (Fig. 26) while simultaneously exerting a light retraction on the colonoscope to straighten the curvature
When passing the splenic flexure, the tip of the scope is left-turned (Fig. 27)
When passing the hepatic flexure, the tip of the scope is turned left and downward (Fig. 28).
Usually all the angling maneuvers of the tip are refined by the simultaneous torque of the shaft of the colonoscope in the same direction while simultaneously advancing or withdrawing the colonoscope to flatten the curve.
8. How to rotate the colonoscope
To stabilize the position of the tip of the colonoscope after passing a bend, the endoscopist should rotate the shaft of the colonoscope in contrary to the bend just passed ('hung on and turn over'). During the intubation, the progression combines a moderate push by the nurse assistant with continuous torques and rotations of the colonoscope by the endoscopist. The torsional movements of the chest of the endoscopist are transmitted to the shaft of the colonoscope with an effect of rotating it of about 45 degrees both to the left and to the right (Fig. 29).
Fig. 29: the endoscopist transmits the torque to the tip of the scope through torsional movements of the chest on the right or on the left
If a greater torsion of the instrument is needed, besides rotating the chest, the operator will turn the handle grabbed with both hands toward the left or the right side (Fig. 30 A-B).
Fig. 30 A-B: if the endoscopist needs to apply a consistent rotation to the shaft of the scope, he/she will add to the rotation of the chest also a movement of the handle toward the left or the right side
During the colonoscopy, such rotations are used to pass some loops of the sigmoid and sometimes in passing a very angled splenic flexure or the hepatic flexure. If the endoscopist needs to negotiate a severe diverticulosis of the sigmoid colon, with significant narrowing of the lumen, the right or left torque of the scope alone are usually sufficient to obtain the progression (Fig. 31), achieved with the aid of a moderate push exerted by the nurse.
Fig. 31: if the sigmoid shows a number of bends, the endoscopist rotates alternatively the shaft of the scope on the right and on the left as soon as the tip of the scope has passed the apex of each bend, to flatten it and proceed to the next one ('hung on and turn over').
9. Modality of scope progression: ‘passive bending’ and ‘active bending’
Whenever possible, the endoscopist uses the 'up-down' and 'left-right' control knobs to hook a bend of the colon and achieve the advancement of the scope (anterior traction of the tip). The basic principle is to reduce as much as possible the friction between colonoscope and colonic wall. As the pressure of the colonoscope on the colonic wall increases (in very angled bends), the modern “passive bending” colonoscopes favor a higher flexibility of the tip; therefore, the pressure (friction) is distributed over a wider arch that eases sliding of the colonoscope and hence its progression.
Fig. 32 A-B: A: if the pressure of the scope is concentrated on a smaller area of the colonic wall (red circle), this would absorb all the vector force (black arrow) and the tip of the scope does not advance (white arrow). In the passive bending colonoscope the increased pressure onto the colon wall triggers the flexion of segment (in yellow) next to the angling segment of the scope. This determines the widening of the pressure arch (green circle), the distribution of the friction (black arrows) and translates the pushing vector force into advancement (white arrow).
Expert endoscopists adopt the so-called “active bending” or “shortening” technique (Fig. 33 A-C), that is to anticipate the most pronounced bends angling the tip (Fig. 33 A), hooking to colonic wall soon after having passed the fold of the curve (Fig. 33 B), so as to slide the scope forward and position the less flexible segment of the scope over the curve itself. Then the maneuver is completed retracting the scope and releasing the tip; the rotation of the axis of the colonoscope makes stable the straightening achieved (Fig. 33 C).
Fig. 33 A-C: with the active bending technique, the tip of the scope hooks the fold at the apex of the bend (A); sharpening the angulation (B), the colonoscope is dragged forward straightening any “parasite” curve (B); releasing the tip, the rotation of the axis of the colonoscope makes stable the rectilinear position.
10. How to straighten the loops of the scope
Conspicuous torques of the colonoscope are necessary, together with its calibrated withdrawal, to reduce an “alpha loop” developed during the insertion phase. In this case the endoscopist stresses both the torsion of the chest and the lateral movement of the handle toward one side (Fig. 35 A-B)
Fig. 35 A-B: if the endoscopist needs to apply a very pronounced torque to the colonoscope, he/she stresses the torsion of the chest, matched with lateral movement of the handle
The photographic sequence shows the interaction of the torque maneuvers applied by the endoscopist on the shaft of the colonoscope (Fig. 36 A-I)
Fig. 36 A-I: pictures illustrating how to rotate the instrument when straightening an alpha loop during the 4-hands intubation technique. Once reduced the loop (H), achieved through a complete right torsion of the chest and simultaneous movement of the handle to the same side, the endoscopist applies a counter-rotation to straighten back the scope (I).