Urological Procedures: Patient Positioning

Positioning in Urological Procedures

Introduction

• Strategic positioning is crucial for accessing the pelvis, retroperitoneum, and perineum.
• Anesthesiologists, urologists, and nurses share the responsibility of:
  • Ensuring patient safety.
  • Providing optimal surgical exposure.
  • Avoiding iatrogenic injuries.

Various Positions

• Lithotomy
• Lateral decubitus & Jackknife position
• Prone position
• Supine Position
• Trendelenburg Position

Lithotomy Position

• Most frequently used position.
• Used for:
  • Transurethral cystoscopic procedures
  • Open urological procedures requiring access to the perineum and anus.
• Patient's anterior superior iliac spine should be placed over the break in the bed.
• Stirrups should be anchored level with the patient's knees and angled toward the contralateral shoulder.
• Upper extremities can be:
  • Tucked at the patient's side in a neutral position.
  • Abducted <90 degrees with arms either supinated or neutral.
• When raising and lowering legs in and out of stirrups, it should be done in unison by at least two OR staff to avoid torsion on the lumbar spine and possible dislocation of either hip.
• The goal of leg positioning in the stirrups:
  • Hips flexed 80-100 degrees from the trunk.
  • Legs abducted <30-45 degrees from the midline.
  • Knees bent until parallel with the torso.
• Stirrups should be padded circumferentially around the lower extremities to avoid compression injuries.
• When lowering the legs out of lithotomy, the knees should be brought together at midline, followed by unflexing the legs back to the supine position.
• Preoperative examination focused on potential limitations to hip, knee, and ankle movement should be noted.
• Multiple versions of stirrups: Candy canes, calf rests, boots, shepherd's crook foot straps, or Bierhoff knee crutch stirrups.

Exaggerated Lithotomy Position

• Involves flexing the hips beyond 100 degrees.
• Should be avoided due to excessive traction on the sciatic and peroneal nerves.
• When necessary, it should be for a limited duration and only during crucial surgical points.
• A buttress should be placed under the lower back to relieve nerve and spinal traction.

Complications of Lithotomy Position

• Peripheral neuropathies
• Lumbar spine torsion
• Dislocation of hip
• Finger trauma

Neuropathies in Lithotomy Position

• Common peroneal nerve:
  • Most common neuropathy.
  • Compression between the lateral head of the fibula and stirrup.
  • Common in low BMI, prolonged duration >3 hours.
  • Lack of dorsiflexion of foot / Paresthesia or numbness.
  • Full recovery is normally observed.
• Sciatic nerve:
  • Most susceptible to stretch injury - exaggerated lithotomy position.
  • Hyperflexion of hip + extension of knee → greatest risk for stretch neuropathy.
• Obturator nerve:
  • Stretched when hips are flexed beyond 100 degrees.
  • Stretched and compressed against the pubic ramus of the pelvis as it exits the obturator foramen.
  • Also at risk when legs are first abducted and then flexed at the hip and knee when placed into the stirrups.
• Posterior Tibial nerve:
  • Sensory and motor supply to the plantar surface of the foot.
  • Compression in the tarsal tunnel.
  • Due to improper padding of lithotomy boots.
• Femoral Nerve:
  • Due to hyperflexion of thigh.
  • Inguinal ligament is stretched & compresses nerve.
• Lateral femoral cutaneous nerve:
  • Sensory innervation to lateral thigh.
  • "Meralgia paresthetica" - Compression of lateral thigh against candy cane stirrup rod.
• Saphenous nerve:
  • Supplies sensory innervation to the medial aspect of foot.
  • Compression against medial tibial condyle.

Lateral Decubitus & Jackknife Position

• Optimal surgical exposure for access to the adrenal glands, kidney, and collecting system.
• Beneficial for removal of stones located in the upper ureter and renal pelvis requiring an open procedure, as well as nephrectomies of non-malignant disease.
• First anesthetized in the supine position, and then the patient is turned to the lateral decubitus position.
• For extraperitoneal surgical procedures, the patient is turned a full 90°; however, if surgical exposure requires access to the intraperitoneal space, then turning 45° lateral may be adequate.
• Maintaining the patient firmly on their side without displacement by anchoring tape over towels placed at the patient's shoulder and waist to the OR bed.

Jackknife Position

• A modification of the lateral decubitus position, in which the OR table is flexed at its midpoint underneath the patient's iliac crest.
• Provides stretch between the nondependent iliac crest and the costal margin on the operative side, creating a maximal surgical exposure.
• Place the table into reverse Trendelenburg until the upper torso is parallel with the ground to optimize both hemodynamic stability and tension over the incision site.
• If additional flexion is needed, a kidney rest can be added to the OR table apparatus.
• The kidney rest should be anchored where the OR table breaks and placed directly under the dependent iliac crest.
• Care should be taken to ensure that the kidney rest is not malpositioned underneath the flank or lower costal margin.
• Such malpositions can result in compression of the inferior vena cava and decreased venous return, as well as impeding ventilation of the dependent lung.
• When turning the patient to the lateral decubitus position, maintain the head and neck in a neutral position in line with the vertebral column.
• The head should be kept neutral by placing blankets and/or a foam doughnut beneath it for support. Failure to do so can result in lateral stretch of the neck and subsequent stretch of the brachial plexus.
• Horner syndrome has also been reported as a possible complication of excessive lateral neck flexion due to injury of the ipsilateral stellate ganglion.
• Attention should also be taken with the dependent eye to prevent external compression or possible corneal abrasion.
• The arms should be placed perpendicular to the shoulders and parallel to each other.
• They should be neither abducted >90 degrees nor flexed at the elbow >90 degrees to avoid stretching of the brachial plexus and its branches.
• The nondependent arm can be either propped up on pillows above the dependent arm or placed on a padded armrest positioned perpendicular to the corresponding shoulder
• Axillary roll is placed under dependent thorax, caudad to the axilla
• The roll should never be located in the axilla itself, as its purpose is to distribute the weight of the thorax away from the axilla and prevent compression of its neurovascular bundle.
• Placing the pulse oximeter on the dependent arm can be used as an indicator of axillary neurovascular compression. If hypotension is recorded in the dependent arm, then axillary compression must be ruled out.
• Periodic checks throughout the surgical procedure should also be performed to ensure that the axillary roll has not become displaced during surgery.
• Dependent leg is flexed at the knee with padding beneath the dependent leg and between both knees to prevent compression at bony prominences

Complications of Lateral Decubitus and Jackknife Position

• Potential Complications:
  • Peroneal Nerve
  • Brachial Plexus
  • Skin breakdown
  • Compartment syndrome
  • Rhabdomyolysis
• Recommendations:
  • Adequately pad dependent leg against the table
  • Use axillary roll
  • Bring dependent shoulder and arm out from under the rib cage
  • Pad pressure points
  • Avoid prolonged surgery
  • Higher incidence in obese or male patients and prolonged surgery

Prone Position

• For access to the retroperitoneum and upper urinary tract procedures
• Commonly used for:
  • Percutaneous nephrolithotomy
  • Adrenalectomy
  • Pediatric pyeloplasty via the dorsal lumbotomy approach
• During positioning, attention should be paid to avoid inadvertent extubation of the trachea and to maintain the neck in neutral position.
• The arms are typically at the patient's sides while turning prone, and can then be tucked with palms facing medially, or extended in the "Superman" position on arm boards with the arms abducted less than 90° at the shoulders and flexed at the elbows
• The knees and hips should be slightly flexed.
• All pressure points, including forehead, chin, elbows, knees, shins, and toes, must be properly padded.
• The chest and abdomen should be supported above the operating table by bolsters or frames to prevent compression of abdominal contents and reduction in pulmonary compliance and venous return.
• Care should also be taken to avoid compression of breasts and male genitalia.
• Breasts should be placed medially to the bolsters that support the chest.
• Commercially available foam headrests have openings for the eyes, nose, and mouth to avoid tissue injury from excessive pressure or endotracheal tube kinking.
• Challenging in the morbidly obese patient, and extra operating room staff should be available to assist with turning the patient.
• Alternatively a technique of awake intubation, followed by patient self-positioning can be employed. This method has been described for percutaneous nephrolithotomy in obese patients.
• The advantage of this technique is that the patient can achieve a comfortable position and can be questioned as to whether additional adjustments or padding are necessary prior to induction of anesthesia.

Complications of Prone Position

• Potential Complications:
  • Occlusion of carotid or vertebral arteries
  • Cervical spine injury
  • Brachial plexus
  • Pressure injuries of knees, breasts, face, and feet
  • Upper airway edema
  • Venous air embolism
• Recommendations:
  • Avoid excessive rotation of neck
  • Avoid excessive extension or flexion of neck
  • Arm elevated <90 degrees or placed at sides.
  • Avoid pressure on axilla
  • Pad pressure points
  • Maintain head in neutral position
  • Avoid lowering heads & legs.

Supine Position

• Majority of open urological procedures, most commonly involving the penis, scrotum, inguinal lymph nodes, and urethra.
• Optimal exposure of pelvic and intra-abdominal organs such as the bladder and prostate.
• Also retroperitoneal surgeries - Adrenals, Kidney & Ureters
• Any urological procedure involving the manipulation of the intestinal tract for urinary diversion or augmentation
• Mostly the patients are asked to position themselves, especially those with a prior history of peripheral neuropathy, contractures, or other risk factors.
• Once anesthetized, care should be taken for further adjustments.
• Upper extremities should be properly secured. Pressure on the ulnar groove and hyperextension should be avoided.
• When in adduction, the hand and forearm should be rotated to a neutral position and secured with a draw sheet underneath the patient
• In abduction - hand and forearm should be in neutral position or supination and the abduction should be <90 degrees.
• Bony prominences should be padded.
• Neck placed in neutral position

Special Considerations for Supine Position

• Patients with chronic back pain or kyphoscoliosis require additional padding or even slight flexion of the bed to avoid exacerbation of their condition
• For long or extended procedures, periodically rotate the head to redistribute the weight and evade pressure alopecia secondary to hair follicle ischemia.
• Avoid leaning on the extremities by OR staff → inhibits venous return and increased risk of DVT

Peripheral Neuropathies in Supine Position

• Ulnar neuropathy:
  • Most common
  • Susceptible as it courses through the medial elbow in the postcondylar groove
• Median neuropathy:
  • Compression at the cubital fossa
  • Avoid hyperextension at the elbow
  • When arm falls unintentionally off the edge of the table in the pronated position
• Radial nerve:
  • Compression - spiral groove of the humerus
  • Distally placed noninvasive blood pressure cuff at elbow
  • Allowing supinated arm to inadvertently hang off the side of the table

Spinal Hyperextension in Supine Position

• Hyperextension beyond 10 degrees → back pain and neuropathies Brachial plexus compression injury:
  • Flexion of head to contralateral side
  • External and dorsal rotation of arm
  • Hyperabduction at the shoulder joint
• To avoid → head and arms in neutral position, with arms abducted <90 degrees

Trendelenburg Position

• Modification of the supine position, by tilting the table and patient head down.
• Often employed to displace the abdominal viscera toward the diaphragm, providing improved exposure to the lower abdominal and pelvic organs.
• Positioning of the arms remains similar to that in the supine position.
• The arms are more preferably, tucked at the patient's side in the neutral position, avoiding the risk of the arms sliding off the arm boards once the patient is tilted.
• Shoulder braces should also be placed bilaterally over the acromioclavicular joints, but only when the arms are tucked at the patient's side.
• Utilization of shoulder braces in combination with arm abduction may result in brachial plexus neuropathy, due to stretching and its potential compression against the humeral head as it courses through the shoulder and upper extremity.
• Trendelenburg position is often a tilt of the bed of <20° in order to displace the viscera.
• Steep Trendelenburg positioning of 30-45° tilt may be necessary; this steep positioning should be avoided when possible.
• It is important to ensure that there is a non-sliding mattress to prevent the mattress and subsequently the patient from sliding cephalad off the OR table.

Complications

• Potential Complications:
  • Brachial Plexus
  • Ischemic optic neuropathy
  • Increased intracranial pressure
  • Head/neck venous pooling.
• Recommendations:
  • Use kidney-shaped shoulder braces/non-sliding mattress
  • Pad acromioclavicular joints
  • Limit time in Trendelenburg position
  • Monitor head and neck for excessive edema
  • Limit time in Trendelenburg position