You have assisted your patient to the prone position, which intervention is the most important?

Treatment

PRONE POSITION (SUBOCCIPITAL APPROACH)

The prone position is used for the suboccipital approach and posterior spinal surgery (Fig. 15-4). The potential for complications is very high. Turning the patient to a prone position could also cause hemodynamic changes, impairment of ventilation, and spinal cord injury. In this approach the patient is placed on two bolsters or a support device with arms to the side of the body. To ensure that abdominal and femoral venous return is not unduly compromised, as well as to allow adequate diaphragmatic excursion, the bolsters should be sufficiently far apart and large enough to not cause pressure on the abdomen. Breasts and male genitalia should be checked to minimize any pressure on them. Arms and knees should be padded. The ankles should be elevated so that the toes are hanging freely. The chin is tucked in the suboccipital approach, which may cause kinking of the endotracheal tube, so an armored tube may be preferred. Facial and airway edema occurs with longer procedures and may necessitate postoperative intubation. Though a rare occurrence, blindness has been reported after surgery in the prone position, particularly in procedures with a prolonged duration, significant blood loss, and hypotension.

3.5.1 Nephrolithotomy With the Patient in Prone Position

The prone position (Fig. 3.18) was adopted because it ensures a wide field for puncturing the kidney, without limiting the movements of the instruments and allowing for a simple execution of multiple tracts.

The physiological lumbar lordosis is more pronounced in the prone position, determining a narrowing of the working field. The patient’s flexion (Fig. 3.19) on the operating table increases the distance between the XII-th rib and the iliac crest, increasing the space through which the adequate puncture of the kidney can be achieved. Also, the approach of the upper calyx is relatively easy, the position allowing the downward access of the nephroscope toward the renal pelvis with minimal tension, the mobile lower pole aligning with the nephroscope’s axis. This type of approach is preferred in obese patients, the upper pole being closer to the posterior abdominal wall (Ray and Honey, 2012).

From a practical point of view, the intervention begins with the patient in the lithotomy position for the retrograde ascent of a ureteral catheter into the pyelocaliceal system. If the patient is placed in the prone position with the lower limbs in abduction (Fig. 3.20), there is the possibility of a simultaneous antegrade and retrograde approach. Identification of the ureteral orifices in the prone position may be more difficult for surgeons who are unfamiliar with this technique. Sometimes, in the case of urinary tract obstruction, objectification of the posterior caliceal groups may be difficult, the urine not allowing the contrast medium to enter these calices located superiorly.

The puncture of the upper calyces is easier in this position than in the case of interventions performed in supine position.

Modifying this position by flexion of the patient on the table by 30–40 degree also determines a downward displacement of the kidney, therefore also modifying the puncture site (e.g., a puncture that in classic prone position is performed in the XI-th space will be performed in the XII-th space after this modification) (Ray and Honey, 2012).

However, performing PCNL in prone position also has some disadvantages. It is associated with a restriction in the patient’s respiratory movements and in consequence is not always possible. Morbid obesity and compromised cardiorespiratory status also provide challenges, both for the anesthesiologist and for the surgeon (Ray and Honey, 2012). Placing the patient in prone position may also be difficult in the case of patients with contractures of the lower limbs.

Moreover, general anesthesia and ureteral catheterism are usually performed with the patient placed in the lithotomy position, and only subsequently the patient is turned over in prone position for the percutaneous approach, these maneuvers increasing the intervention’s duration.

Also, the prone percutaneous approach does not completely eliminate the risk of complications. Studies conducted in large groups of patients have demonstrated a rate of 3–10% of acute bleeding that requires transfusions and an incidence of 0.5% of colon perforations (LeRoy et al., 1985; Segura et al., 1985; Jones et al., 1990). In the case of complex lithiasis, the success rates of prone PCNL vary between 74% and 83%, while the rate of transfusions ranges between 14% and 24% (Preminger et al., 2005).

In an attempt to improve the results and to overcome these limitations, with the increase in experience the high number of combined procedures has led to the modification of the prone PCNL technique. Thus, relatively recent studies using modern imagistic methods have demonstrated the safety of placing a lateral percutaneous nephrostomy (Krasny and Deseran, 1997; Boon et al., 2001; Prassopoulos et al., 1990).

8 What specific concerns are associated with the prone position?

The prone position results in a cephalad displacement of the diaphragm. Chest rolls are used to decrease abdominal compression, improving diaphragmatic excursion while limiting compression on the aorta and inferior vena cava. Proper padding of all pressure points, including the face, eyes, ears, arms, knees, hips, ankles, breasts, and genitalia, is necessary in this position. The arms should be placed in a neutral position to avoid traction on the brachial plexus, although modest abduction >90 degrees is acceptable. Electrocardiogram electrodes should not be placed so the patient is lying on them.

Prone Position

The prone position is used for lesions in the midline posterior fossa or the occipital region. A lateral position can also be used if there is laterality to the lesion with the dependent arm supported by an arm sling. The head is flexed (keep two fingers' breadth between the chin and the sternum) and lifted in the sagittal plane to make the line along the head and neck relatively flat, to open the cranial-cervical junction, and to provide an optimal visualization angle. The nipples and genitals should be free from direct pressure, and the head and feet are positioned higher than the heart to facilitate venous return (Fig. 6.7).

Positioning

Positioning is an especially important consideration in pediatric neuroanesthesia. Children with increased ICP should be transported to the preoperative holding area and operating room with the head elevated in the midline position to maximize cerebral venous drainage.

After the child is in the operating room, the neurosurgeons and anesthesiologists must have adequate access to the child. In infants and small children, slight displacement of the tracheal tube can result in extubation or endobronchial intubation. During prolonged procedures, it is important for the anesthesiologist to be able to visually inspect the tracheal tube and circuit connections and to suction the tracheal tube when necessary. Using proper draping and a flashlight, the operator can usually create a “tunnel” to ensure access to the airway. All but very small children are placed in pins in a Mayfield head holder (Integra, Plainsboro, NJ). The direction of the tube exiting the nares should be adjusted to remove pressure and avoid the risk of ischemia, particularly for cases that will continue for several hours. Neonates and small infants have thin calvaria, so head-pinning systems are often avoided. Instead, there are a variety of non–pin-based headrests available for these children. Adequate padding should be used in such situations (Figs. 26.4 and 26.5). Extreme head flexion can cause brainstem compression in children with posterior fossa pathology, such as a mass lesion or Arnold-Chiari malformation. Extreme flexion can also cause high cervical spinal cord ischemia and tracheal tube kinking and obstruction.75

Extremities should be well padded and secured in a neutral position (i.e., palm supinated or neutral to avoid ulnar nerve compression). It is important to avoid stretching peripheral nerves and to prevent skin and soft tissue pressure injury because of direct contact with surgical accessories such as instrument stands and grounding wires (see Fig. 26.5). It is also important to ensure that extremities that are not directly visible to the anesthesiologist (e.g., those on the opposite side of the operating room table) cannot fall off the table during surgery, even if the table is rotated. In older children and adolescents undergoing prolonged procedures, deep vein thrombosis prophylaxis should be considered using compression or pneumatic stockings.76,77

PRONE HEAD-ELEVATED POSITIONING

In the prone position, the chest wall is stabilized and thoracoabdominal asynchrony is reduced.95 Several studies have demonstrated that the prone position reduces apnea rate in preterm infants, with some also reporting a decrease in desaturation rate.95–98 An extension of the prone position is the head-elevated prone tilt position, which in a cross-over study on 12 neonates was associated with a 49% reduction in desaturations to less than 85% compared to the horizontal prone position.99 Recently, however, two studies reinvestigated the issue, driven by the observation that infants appear more comfortable when only the chest rather than the entire body is being tilted. Whereas one found a slight (-13%) but statistically significant reduction in desaturation rate compared to the horizontal position,100 the other did not find an advantage for either position (own unpublished data). Thus, the effect of head-up positioning on bradycardia and intermittent hypoxia may be less pronounced than previously thought. As it does not appear to have any deleterious effect, we continue to consider it a first-line intervention for infants with AOP. Infants, however, should be placed in supine position approximately 1 week prior to discharge to set an example for the sleep position that should be adopted at home (see primary prevention).

Prone Position

The prone position refers to three primary patient configurations: straight prone, Concorde, and kneeling (Figs. 4.6 to 4.8). In general, the prone position is used for access to the suboccipital region and the posterior spine. For prone procedures the patient is placed under general anesthesia and intubated on the hospital bed in the supine state. Vascular access is also obtained and a bladder catheterization occurs prior to placing the patient into the final position on the operative table.3

Extreme caution should be used when rotating the patient from the hospital bed to the prone position on the operative table, particularly in cases of presumed or known spinal instability. The surgeon, not the anesthesiologist, should be responsible for control of the cervical spine and skull during this maneuver. Gripping the Mayfield clamp during this step does not provide optimal craniocervical stabilization. Instead, the Mayfield clamp should be locked in place, the surgeon’s receiving hand should be placed directly onto the patient’s face with the endotracheal tube stabilized between two fingers on the same hand, and the surgeon’s other hand should be placed on the occiput. This configuration offers maximal airway protection and control of the patient’s cervical spine and skull simultaneously. All members of the team should monitor intravenous/arterial lines, catheters, and tubing during this transition. Many of the circuits are intentionally disconnected prior to this maneuver.1,2,7

The use of large gel pads for the chest or special padded frames or tables allows for appropriate cushioning while preventing excessive thoracoabdominal compression. Female breasts and nipples should be positioned medially and male genitalia should hang freely.3 The patient’s knees are padded and usually flexed. The wrists and elbows are also appropriately padded.5 The neck is maintained in either a neutral or flexed position, the degree of which is determined by the surgeon and the indication for surgery. The head may or may not be fixed and can be tilted up to 30 degrees to one side and rotated up to 45 degrees, also depending on the precise location of the pathology being treated and surgeon preference.2

Posterior cervical surgeries may be performed with the patient in a three-point headholder, halo ring, or traction tongs, or with the face on a padded pillow with cutouts for the endotracheal tube and eyes. Special consideration should be given to corneal lubrication, lid taping, and eye positioning so as to avoid ocular pressure that may lead to blindness.2,8 The neck is often maintained in a neutral position, particularly if fusion is desired. For thoracolumbar surgeries, the patient is often placed on a Jackson table or Wilson frame, and the head is placed on a padded pillow with cutouts as mentioned earlier.2 For spinal procedures in which intraoperative x-rays are planned, it is important to consider the placement of the patient’s arms. For thoracolumbar procedures the arms are maintained in abduction at approximately 90 degrees at the shoulder and elbow (“airplaned”) on arm rests. For cervical and cervicothoracic junction procedures, the arms are often padded and wrapped at the patient’s side. To enhance radiographic visualization of the cervicothoracic junction, traction applied toward the feet by using either tape on the shoulders or soft wrist restraints anchored to the foot of the bed is often necessary. However, excessive traction should be avoided because it can lead to neuromuscular and vascular injuries, cutaneous burns, and very rarely joint dislocation.3,5

For cranial approaches, especially the occipital transtentorial and supracerebellar infratentorial approaches, the Concorde position is advocated. In this position, the skull is fixed in pins, the patient’s neck and knees are flexed, the arms are maintained in the neutral position at the side with thumbs pointing downward, and the thoracolumbar region is extended so that the head is elevated slightly above the level of the heart. The Concorde position is commonly used for suboccipital approaches and has a relative benefit over the sitting position (used for similar surgical approaches) in that it is associated with a significantly lower incidence of venous air embolism.1,9

Finally, the kneeling prone position is rarely used. In this position, the patient is placed on an operative table that approximates the outline of the letter Z. Historically patients were placed in the kneeling position to minimize the amount of intraoperative blood loss. Although this was demonstrated clinically and experimentally, the disadvantages of the kneeling position are well documented and include increased potential for neurovascular and muscular pressure injuries,5 hypotension from pooling of blood in the dependent lower extremities, a concomitant increase in the incidence of venous thrombosis and pulmonary embolism, and muscle necrosis and rhabdomyolysis that can lead to renal failure. For these reasons, placing the patient in the kneeling configuration is rarely justified.2

Prone Head-Elevated Positioning

In the prone position, the chest wall is stabilized and thoraco-abdominal asynchrony reduced. Several studies have demonstrated that the prone position reduces the apnea rate in preterm infants.53,54 A 15° head-elevated tilt prone position was even associated with a 49% reduction in desaturations to <85%.55 Recently, however, two studies re-investigated the issue, and found only a slight (−13%) reduction in the frequency of desaturation/bradycardia compared to the horizontal position; one found no advantage even for the head-up tilt position.56,57 This much less clear advantage of the head-up tilt position may be due to the fact that infants in the earlier study55 had received no other treatment for AOP, whereas in the more recent ones all had received caffeine, and most CPAP. Thus, positional effects on AOP may be less pronounced in infants already receiving caffeine. The prone, head-up tilt position may therefore be considered as a first-line intervention for AOP, but offers little additional effect in infants already treated with caffeine or CPAP.

Technique: Gua sha to hips, prone position

In the prone position, palpate and needle the sacral and lateral sacral areas as well as channels distally that course through the hip and sacral area. There are trigger points here for the knee and leg. Gua sha strokes should follow anatomical lines, from sacral edge outward and slightly downward. When these areas are treated the Qi and Blood can flow properly to the extremity. Treating the extremity without clearing the corresponding trigger points on the body can result in a worsening of the extremity condition. Dredging the channels reestablishes a circuit that both feeds and drains the distal problem area with Qi and Blood.