Jennifer Thompson

N581 KPSANPositioning in Anesthesia

Readings: Nagelhout Ch. 21Barash Ch 28

Objectives:

1. Explain the importance of proper positioning.

2. Identify the most common nerve injuries due to improper positioning.

3. List common problems with positioning.

4. Identify the high risk patient for developing postoperative nerve damage.

5. Demonstrate the proper positioning of the supine, trendelenberg, reverse

trendelenberg, sitting, lithotomy, lateral and prone patient.

6. Identify the physiologic effects of each position and variation thereof.

7. Identify common complications due to improper positioning for each of the

positions.

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Jennifer Thompson

N581 KPSANImportance of Positioning

Goal:To offer maximum anatomical access that is physiologically safe for the anesthetized patient.

Problems with Positioning May evoke undesirable physiological changes Anesthesia may blunt normal protective mechanisms Complexity of positioning due to minimally invasive surgery and creative

incisions

Categories of positioning problems Respiratory Problems

Circulatory problems

Nerve, muscle injuries

Soft tissue injuries

Potential Position-Related Injuries

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Jennifer Thompson

N581 KPSANSystem Potential InjuryHead, eyes, ears, nose, and throat Blindness

Corneal abrasionFacila edemaVocal cord edema

Cardiovascular Vascular occlusionDeep vein thrombosisIschemic injuriesVAE

Respiratory AtelectasisEndobronchial intubationTube dislodgementAspiration

Neurologic Peripheral neuropathyQuadriplegiaDecreased cerebral blood flowIncreased intracranial pressure

Genitourinary MyoglobinuriaAcute Renal Failure

Musculoskeletal AmputationBackacheCompartment SyndromeRhabdomyolysis

Integumentary AbrasionAlopeciaDecubiti

Factors Associated with Position-Related InjuriesPositioning Devices

Table StrapsLeg Holders and StirrupsAxillary RollBolstersFracture table postShoulder BracesPositioning framesHeadrestEther screen

Length of ProcedureLonger than 4-5 hours

Body HabitusObesityMalnutrition

Preexisting PathophysiologyAnemiaDiabetes mellitusPeripheral vascular diseaseLiver diseasePeripheral neuropathiesRenal failureLimited Joint mobilitySmokingSkin conditionAlcoholism

Anesthetic TechniqueGeneral AnesthesiaHypotensive techniquesNeuromuscular blockade

Bulky musculatureMost Frequent Claims for Nerve Injury by Gender

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Jennifer Thompson

N581 KPSANNerve # Claims % of 445 % Female % MaleAll nerve damage claims 445 100% 49% 51%

Ulnar Nerve 113 25% 21% 79%

Brachial Plexus 83 19% 57% 43%

Spinal Cord 73 16% 49% 51%

LumbosacralNerve Root 67 15% 70% 30%

Sciatic Nerve 23 5% 61% 39%

Positioning adjuncts:

Attach to the OR tableArmboardsLateral Positioning devices and postsLithotomy stirrupsHead rest

Do not attach to the OR tableGel padsPositionersPillowsEggcrate foamVacuum bean bagsSand bagsBolsters

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Jennifer Thompson

N581 KPSANCommon surgical positions:Supine Used For:Surgeries of the face, head and neck, chest abdomen and extremities thyroidectomy, chest , abdomen, ORIF, ext fixation of extemities

Establishing position:

Arm position on arm board. Arm tucked at patient’s sideAbduction of arm should be limited Arm in neutral position with palm to hipto less than 90 degrees whenever The elbow is padded,possible. The arm is supinated, and one needs to ensure and the elbow is padded. that the arm is supported. Pressure points: Thoracic vertebra Scapula Olecranon Sacrum Coccyx Calves Calcaneous

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Note the asymmetry of the base of the table, placing the patient’s center of gravity over the base if positioned in the usual direction.

Jennifer Thompson

N581 KPSANVariations:

Trendelenberg/Reverse TrendelenbergUsed For:

Support devices:

Shoulder bracesBean bagsLap beltArm boardsEgg crate paddingShoulder rollPillowsFoot rest

Establishing Position:

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Flexion of the hips and knees decreases tension on the back.

Jennifer Thompson

N581 KPSAN

Variations:Steep T-berg/Reverse T-berg/Thyroidectomy/Beach Chair

Physiologic Effects of the Dorsal Decubitus Position:

Cardiovascular:

Respiratory:

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Head-elevated positions often used for operations about the ventral and ventrolateral aspects of the head, face, neck, and cervical spine. A. The legs are at approximately heart level and the gradient into the head is appreciable but slight. B. The flat table and foot rest are useful when a thyroidectomy is planned under regional anesthesia.

Jennifer Thompson

N581 KPSAN

Other:

Complications of the Dorsal Decubitus Positions:

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Ulnar nerve injury

Optimal position for shoulder brace is above the lateral 2/3 of the clavicleArm should be maintained at 90 deg or lessShoulder brace too lateral may cause compression of the brachial plexus below the head of the humerus which is forced into the axillaToo medial: compression of the brachial plexus between the depressed clavicle and the first rib

Jennifer Thompson

N581 KPSAN

LithotomyUsed For:Procedures of the perineal structures. D&C’s, vaginal deliveries, hysteroscopy, hysterectomy, cervical surgery, TURP, Hemorrhoidectomy

Support devices:StirrupsCandy Canes

Establishing Position:

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Hips are flexed 80 to 100 degrees with lower leg parallel to body. Arms are on armrests away from hinge point of foot section.

Jennifer Thompson

N581 KPSAN

Lithotomy position with correct position of “candy cane” stirrups well away from lateral fibular head

Pressure Points: The Occiput Thoracic vertebrae Medial and lateral epicondyles Olecranon Process Scapula Sacrum Femoral Epicondyles Medial and Lateral Malleolus Calcaneous

Variations:

Physiologic effects of the Lithotomy position:

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Jennifer Thompson

N581 KPSAN

Cardiovascular:

Central circulation autotransfusion:

Hypoperfusion:

Hypotension:

Repiratory:

Further decrease in FRC by 15-20% due to restriction of diaphragmatic movement.

Other:

Complications of the lithotomy position:

Peroneal Nerve Damage:

Saphenous Nerve Damage:

Hip and knee damage:

Obturator nerve damage:

Torque of the spine:

Vertebral artery injury

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Jennifer Thompson

N581 KPSAN

Femoral Nerve Damage:

Compartment Syndrome:

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  Improper position of arms in lithotomy position with fingers at risk for compression when the lower section of the bed is raised.

Jennifer Thompson

N581 KPSANLateral decubitusUsed for: Esophagoscopy, thoracotomy, hip surgery, nephrectomy, excision of truncal masses, AAA

Support devices:Axillary rollsPillowsArm positionersBean Bags

Establishing Position:

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 Lateral decubitus position showing placement of arms and head. Note additional padding under headrest to ensure alignment of head with spine. Headrest should be kept away from dependent eye. Arm should be level with the shoulder.

Note flexion of lower leg, padding between legs, and proper support of both arms.

Jennifer Thompson

N581 KPSAN

Pressure Points: The ear Acromion Process Olecranon The ribs Iliac Crest Greater Trochanter Medial and Lateral Condyles Medial and Lateral Malleolus

Variations:

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Flexed lateral decubitus position. Point of flexion should lie under iliac crest, rather than the flank or lower ribs, to optimize ventilation of the dependent lung. 

Use of axillary roll in lateral decubitus position. Roll, in this case a bag of intravenous fluid, is placed well away from axilla to prevent compression of the axillary artery and brachial plexus.

Jennifer Thompson

N581 KPSAN

Physiologic Effects of the Lateral Decubitus Position:

Cardiovascular:

Respiratory:

Other:

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The semisupine position with dorsal pads supporting the torso, the extended arm padded at the elbow, and the elevated arm restrained on a well-cushioned, adjustable overhead bar (A). Axillary contents (B) are not under tension and are not compressed by the head of the humerus, and a pulse oximeter ensures that the digital circulation is not compromised. The position is safe only if the arm does not become a hanging mechanism to support the torso.

Jennifer Thompson

N581 KPSANComplications of the Lateral Decubitus Position:

Other:

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Medial-to-lateral view of right elbow. The cubital tunnel retinaculum (CTR) is lax in extension (A) as it stretches from the medial epicondyle (ME) to the olecranon (Ol). The retinaculum tightens in flexion (B) and can compress the ulnar nerve (arrow).

Circumduction of the arm displacing the scapula and stretching the suprascapular nerve between its anchoring points at the cervical spine and the suprascapular notch.

Jennifer Thompson

N581 KPSAN

SittingUsed For:Shoulder surgery, Brain tumors, hematoma evacuations, brainstem surgery

Support devices:Mayfield head pinsHead strapsFoot rest

Establishing Position:

 

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“Sitting” position with Mayfield head pins. This is actually a modified recumbent position as the legs are kept as high as possible to promote venous return. Arms must be supported to prevent shoulder traction. In a commonly used variation they are padded and rest on the abdomen, as illustrated in Figure 63-8. Note that the head holder support is preferably attached to the back section of the table so that the patient’s back may be adjusted or lowered emergently without first detaching the head holder. If the head holder is connected to the thigh section of the table this cannot be done.

Sitting position adapted for shoulder surgery. This is sometimes called the “beach chair position”. Arms must be supported to prevent stretching of the brachial plexus.

Jennifer Thompson

N581 KPSANPhysiologic Changes of the Sitting Position:

Cardiovascular:Rapid changes in position can cause hypotensionVenous pooling due to decreased central blood volume can decrease CODecreased BP

Respiratory:Increased FRCIncreased lung volumesPossible ETT migration

Other:Decreased cerebral circulationBP should be measured by placing the arterial line transducer at ___________.

Complications of the Sitting Position:

Brachial Plexus injury

C-spine injury

Hypotension

ETT migration

Venous Air Embolism (VAE):o There is an increased negative venous pressure in veins above the heart. o Once the skull cap is removed, the veins in the bone remain stented open (as

opposed to veins in soft tissue which are collapsible when elevated above the heart)

o Open veins can allow entry of air into the venous system progressing through the venous circulation and into the heart (right side)

o This can cause a R ventricular outflow obstruction resulting in reduced CO and decreased BP.

o A large venous air embolism that reaches the pulmonary circulation increases alveolar dead space, causes a severe V/Q mismatch leading to hypoxemia, hypoxia, and hypocapnea.

o Arterial air embolism can occur when air emboli pass through from the right heart to the left heart into arterial circulation ( in patient’s with atrial/septal defects or patients with a patent foramen ovale) causing ischemia and infarction of the brain and heart.

o This can occur in any surgery where the incision is located above the level of the right atrium but is very rare due to the collapsibility of veins in soft tissue.

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Jennifer Thompson

N581 KPSAN

How to assess a VAE: Transesophageal echocardiography Precordial Doppler Increased end-tidal nitrogen (>0.2 mmHg) Decreased end-tidal CO2 (3mmHg) Increased PAP (>3 mmHg) Decreased MAP (>10 mmHg) Dysrhythmias

What to do. Notify surgeon to flood the field with water to identify any source and prevent

further air from entering circulation Call for help Place the patient in a reclining supine position or trendelenberg position if

possible Aspirate from the central venous catheter D/C Nitrous Increase venous pressure by using jugular venous compression or by

positioning Support BP and CO with catecholamines

Prone (ventral decubitus)Used For:

Support devices:

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Jennifer Thompson

N581 KPSAN

Establishing Position:

Bony structures of head and face are Prone position with horseshoe adaptersupported, and monitoring of eyes Head height is adjusted to positionand airway is facilitated with a plastic neck in a natural position.mirror.

Mayfield Tongs

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  Prone position with Wilson frame. Arms are abducted less than 90 degrees whenever possible. Pressure points are padded, and chest and abdomen are supported away from the bed to minimize abdominal pressure and preserve pulmonary compliance. Soft head pillow has cutouts for eyes and nose and a slot to permit endotracheal tube exit. Eyes must be checked frequently.

Jennifer Thompson

N581 KPSAN 

 

Pressure Points The ears Eyes Cheeks Acromion Process Breasts Anterior Iliac Spine Male genitalia Patella Toes

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Prone position, face seen from below. Horseshoe adapter permits superior access to airway and visualization of eyes. Width may be adjusted to ensure proper support by facial bones.

 Prone position with Mayfield head pins. Rigid fixation is provided for cervical spine and posterior intracranial surgeries. Head position may include neck torsion or flexion that affects endotracheal tube position.

Jennifer Thompson

N581 KPSAN

Physiologic Changes in the Ventral Decubitus Position:Cardiovascular:Compression of abdominal contentsEngorgement of veins within the spinal canalVena Cava compressionAorta compression

Respiratory:

Other:

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Jennifer Thompson

N581 KPSANComplications of the Ventral Decubitus Position:

ETT dislodgementBrachial Plexus InjuryBreast/Genitalia InjuryFacial Edema

Thoracic Outlet Syndrome:

Injury to the team:

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Jennifer Thompson

N581 KPSANPostoperative Blindness:

Retrospective analysis of patients who reported visual loss < 7 days postop

  Ischemic Optic Neuropathy (ION)

Central Retinal Artery Occlusion (CRAO)

Etiology Intraop ↓ BPProlonged surgery↑ Blood loss↑ Crystalloid infusion

Direct external pressureEmboli

Mechanism IschemiaOrbital edema → stretch and compression of ON

↓Ocular perfusion pressure

Clinical Features

PainlessBilateral↓Light perception↓ Visual fields

PainlessUnilateralPeriorbital swelling or ecchymosis

Strategies to minimize complications/injury:

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SPINE 72%

MISC. 10%ORTHO. 4%

VASCULAR 5%

CARDIAC 9%

Distribution of cases from the ASA Distribution of cases from the

ASA POVL RegistryPOVL Registry

PION 60%AION 20%

Unknown

9%

CR

AO 11%

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Jennifer Thompson

N581 KPSANDocumenting Patient Position

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Jennifer Thompson

N581 KPSANMost Common Nerve Injuries in American Society of

Anesthesiologists Closed Claims Database after 1990Injury Recommendations for PreventionUlnar nerve (25%) Avoid excessive pressure on postcondylar groove of humerus

  Keep hand and forearm either supinated or in neutral position

Brachial plexus (19%) Avoid the use of shoulder braces in patients in Trendelenburg position (use nonsliding mattresses)

  Avoid excessive lateral rotation of head either in supine or prone position

  Limit abduction of the arm to <90 degrees in supine position

  Avoid placement of high axillary roll in decubitus position—keep roll out of axilla

  Use ultrasound to find internal jugular vein for central line placement

Spinal cord (16%) and lumbosacral nerve root (15%)

Be aware that the fraction of spinal cord injuries is increasing, probably in relation to use of epidural catheters for pain management

  Follow current guidelines for regional anesthesia in anticoagulated patients*

Sciatic and peroneal (5%) Minimize time of surgery in lithotomy position

  Use two assistants to coordinate simultaneous movement of both legs to and from lithotomy position

  Avoid excessive flexion of hips, extension of knees, or torsion of lumbar spine

  Avoid excessive pressure on peroneal nerve at the fibular head

Median (4%) and radial (3%)

Be aware that 25% of injuries to the median and radial nerves were associated with axillary block, and 25% of injuries were associated with traumatic insertion or infiltration of an intravenous line

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Jennifer Thompson

N581 KPSAN

Nerve Summary Chart- ArmNerve How Injured Result of InjuryBrachial Plexus Excessive Abduction

Improper ax roll placementCmprsn from shoulder brace

Weak arm function

Radial Compression against the table or BP cuff.

Inability to extend the wristInability to abduct thumbWrist dropDecreased sensation over dorsal surface of lateral hand

Ulnar Compression against the table

Claw handSensory loss fifth digit

Median Indiscriminate probing of the AC fossa during venipuncture

Loss of sensation of fingertips from thumb to ring fingerInabilty to oppose thumb and fifth digitDecreased sensation on palmar surface of the lateral three digits

Musculocutaneous Compression injury Inability to flex forearmIntercostobrachial Surgery of axillary nerve Numbness or dysesthesia of

the upper/inner arm

Nerve Summary Chart - LegNerve How injured Result of InjurySciatic Excessive hip flexion

resulting in excessive stretchIM injections

Weakness of all muscles below the kneeFoot dropPain or numbness of lower leg, thigh or foot

Femoral Extreme abduction of the thigh with external rotation of the hip

Decreased or absent knee jerkLoss of flexion of hip and extension of the knee

Saphenous Compression injury Paresthesias along the medial and anteromedial side of calf

Common Peroneal Compression injury or hyperextension

Foot dropLoss of dorsal extension of toes.Inability to evert foot

Obturator Excessive flexion of the thigh

Inability to adduct the leg

Anterior Tibial Plantar flexion of the feet for extended periods of time

Foot drop

Lateral Femoral Cutaneous Nerve Entrapment Pain and dysesthesia over lateral thigh

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Jennifer Thompson

N581 KPSANReferences

American Society of Anesthesiologists Task Force on Prevention of Perioperative Peripheral Neuropathies: Practice advisory for the prevention of perioperative peripheral neuropathies. Anesthesiology 2000; 92.

Cassoria L & Lee J: Patient positioning and anesthesia. In: Miller, RD ed. Miller’s Anesthesia. 7th ed. Philadelphia, PA: Churchill Livingstone Elsevier; 2010: 1151-1170.

Cheney FW, et al.: Nerve injury associated with anesthesia: a clinical closed claims analysis, Anesthesiology. 1999; 90(4): 1062–1069.

Choi SJ, et al.: The effects of the exaggerated lithotomy position for radical perineal prostatectomy on respiratory mechanics, Anaesthesia. 2006; 61(5): 439–443.

Litwiller JP, Wells RE, Halliwill JR et al: Effect of lithotomy positions on strain of the obturator and lateral femoral cutaneous nerves. Clin Anat 2004; 17: 45.

Martin JT, Warner MA (Eds): Positioning in Anesthesia and Surgery, 3rd edition. Philadelphia, WB Saunders, 1997.

O’Connell MP: Positioning impact on the surgical patient, Nurs Clin N Am. 2006; 41: 173-192.

Prielipp RC, et al.: Ulnar nerve injury and perioperative arm positioning, Anesthesiol Clin North America. 2002; 20(3): 589–603

Prisk GK, et al.: Pulmonary perfusion in the prone and supine postures in the normal human lung, J Appl Physiol. 2007; 103(3): 883–894.

Thompson, J. L. . Positioning for Anesthesia and Surgery. In: Nagelhout, JJ, Plaus, KL, eds. Nurse Anesthesia, 5th ed. St. Louis: Saunders, 2013: 22:420-440.

Warner, MA. Patient Positioning and Related Injuries. In: Barash, PG, Cullen, BF, Stoelting, RK et al (eds). Clinical Anesthesia, 6th ed. Philadelphia: Lippincott, 2009;30:793-814.

Winfree CJ et al: Intraoperative positioning nerve injuries, Surgical Neurology. 2005; 63: 5-18.

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