Positioning -Student PDF

Positioning Jennifer Oakes, DNAP, CRNA Texas Christian University Essentials of Nurse Anesthesia and Simulation 1 Readings Barash Pg. 809-825 Roth, S. Perioperative visual loss: what do we know, what can we do?. British Journal of Anaesthesia, 103, i31-i40. 2 Objectives Students will: Identify eleme...

Positioning Jennifer Oakes, DNAP, CRNA Texas Christian University Essentials of Nurse Anesthesia and Simulation 1 Readings Barash Pg. 809-825 Roth, S. Perioperative visual loss: what do we know, what can we do?. British Journal of Anaesthesia, 103, i31-i40. 2 Objectives Students will: Identify elements of positioning with regards to patient safety and physiology Examine specific positions, their indications, proper technique, and potential complications Determine factors that are within their control for preventing injury Identify peripheral nerves at risk for injury during surgical procedures Describe physiology of eye injuries and theories of prevention in the operating room setting Describe assessment criteria for identifying and treating nerve injuries 3 Basics of Positioning Everyone in the Operating room SHARE the responsibility for proper positioning Jewelry and hair ornaments are removed Pad surfaces, lumbar support, and natural joint position Do not allow Patient to lie on tubes and wires Head should remain midline Never allow pressure on the eyes Use safety straps 4 Positioning Goals Provide the surgeon the maximum acceptable access to anatomic target while maintaining patient safety Must avoid exceeding patient comfort If a limb does not bend a certain way before anesthesia, don’t try to make it bend that way after anesthesia 5 Cardiovascular Normal physiology in an awake patient when supine Venous return increases Preload increases Stroke volume increases Cardiac output increases Arterial blood pressure increases 6 Cardiovascular, cont. Compensatory response: Baroreceptors from the aorta (via Vagus nerve) decrease sympathetic outflow and increase parasympathetic impulses to SA node and myocardium Results in decrease in HR, SV and CO Arterial blood pressure in maintained within a narrow range 7 Add Anesthesia ?What does general anesthesia do to baroreceptor response? 8 General Anesthesia Interferes with venous return Decreases arterial tone Decreases autoregulatory mechanisms Patients are vulnerable to uncompensated circulatory effects of changes in position 9 Cardiovascular Response Volatile anesthetics cause myocardial depression and vasodilatation Decreases heart rate and blood pressure Muscle Relaxants Decrease venous return due to decreased muscle tone Opioids Slow heart rate=decreased CO and BP 10 Pre-existing conditions To make matters worse…. Airway diseases Poor cardiac function Obesity Ascites Light anesthesia What can you do about it? Anticipate changes Monitor blood pressure frequently Increase IV fluids Adjust the level of anesthesia Give vasopressors Temporary head-down position Postpone further positioning alterations until stable Patient positioning is always secondary to patient safety Pulmonary Concerns Anesthetized patients who are breathing spontaneously: Reduced tidal volumes Reduced functional residual capacity (FRC) Increased closing volume VQ mismatch Diaphragm shifts toward nondependent portion of lungs Variations in pulmonary changes specific to certain positions 13 14 Respiratory Effects Review West’s zones of the lung. Zone 1 PA>Pa>Pv Zone 2 Pa>PA>Pv Zone 3 Pa>Pv>PA 15 VQ Mismatch HPV- Hypoxic Pulmonary Vasoconstriction Maintains optimal V/Q matching Poorly ventilated alveoli also receive less blood flow. Diminishes the degree of dead space ventilation Add General Anesthesia… Volatile Anesthetics () 17 Help the V/Q mismatch 18 To prevent development of significant V-Q imbalance during use of controlled ventilation, tidal volumes must be used that are greater than the average amount that is sufficient for the spontaneously breathing conscious pt. Compare and contrast the awake spontaneously breathing pt and the paralyzed mechanically ventilated pt in the lateral position. Peak Airway Pressures How would you attempt to decrease Peak pressures during mechanical ventilation in the paralyzed anesthetized patient? Hint: deepen anesthetic, muscle relaxation, decrease Vt and increase Rate, change I:E ratio from 1:2 to 1:1.5. Consider Pressure Control ventilation due to its decelerating waveform. 19 Position Documentation The only thing that represents what was done in the operating room in a court of law is your testimony and your documentation. How much do you think you can remember from one case to the next and how much of your “story” will the court officers “believe” without your careful documentation in the anesthesia record? What to document? Pre-operative patient limitations in movement strength and nerve abnormalities. Does the patient have numbness tingling or loss of sensation to any extremity preoperatively? Does the patient have foot drop? 20 Mask Injuries Face straps which are tight across the patients face with prolonged use may cause injury to the facial nerve. 21 Facial Nerve 5 Branches of the Facial Nerve: “Two zebras bit my cat” Temporal Zygomatic Bucal Mandibular Cervical The Bucal is the most likely to be injured by facemask straps. 22 Anatomy Know the Anatomy! Know superior, inferior, anterior, posterior, distal, proximal, pronation, supination, medial, lateral, caudal, cephalad, dorsal, ventral, dependent, non-dependent, flexed, extended Supination Correct anatomical position is lying at attention Palms are ventral surface so ventral to ventral Dorsal to dorsal mean back of hands to down in the supine position. 24 Nerve Damage 27 Causes of Positioning Nerve Injuries Not 100% sure Theories: Soft tissue is compressed resulting in ischemia Inflammatory responses Reactivation of dormant viruses Stretched nerve 28 Brachial Plexus Anatomy Robert Taylor Drinks Cold Beer Roots, Trunks, Divisions, Cords, Branches 32 Draw the Brachial Plexus NTK Brachial Plexus Know: Basic structure Spinal roots (C5, C6, C7, C8, T1) RTDCB and where they change 5 terminal branches (Musculocutaneous, Axillary, Radial, Median, Ulnar) 3 trunks (Superior, Middle, Inferior) 34 Compartment Syndrome When perfusion is inadequate Ischemia hypoxic edema elevated tissue pressure within fascial compartment Rhabdomyolysis 37 Compartment Syndrome Suspected causes of compartment syndrome during surgery Systemic hypotension Vascular obstruction External compression of the elevated extremity by straps or leg wrappings Tight Arm straps Prolonged lithotomy >5 hours 38 Positions Supine Modified supine Lithotomy Lateral Prone Sitting 39 Supine Most common position for surgery Hemodynamic reserve is best maintained Entire body is close to level of heart 40 Modified Supine Lawn chair position Decreases tension on the back Venous drainage from lower extremity is increased 41 Modified Supine Frog-leg position Knees and hips are flexed and hips are externally rotated Allows access to perineum, medial thighs, genitalia, and rectum Careful positioning to prevent dislocation of hips. Support knees 42 Field Avoidance Field Avoidance is a maneuver where the patient’s head is turned away from the anesthetist either 90 or 180 degrees. What would you do differently if the patient is turned 180 from you? 43 Trendelenburg Supine patient tilted down Increases venous return Improves exposure during abdominal and laparoscopic surgery Prevents air embolism 44 Steep Trendelenburg 45 Complications of Trendelenburg position Increases central venous pressure Increases intracranial pressure Increases intraocular pressures Note: the head is at a different level than the heart Effect hydrostatic gradient on cerebral arterial and venous pressures. 46 Complications of trendelenburg Air Leak test Verifies that airway edema is minimal to allow for patent airway after extubation. Spontaneously ventilating patient Deflate cuff of ETT Occlude ETT Watch and listen for air able to pass around tube May also visualize larynx with fiberoptic scope to assess edema 48 Arm positions Abduct 90 degrees patient has increased chance of brachial plexus injury by caudad pressure in axilla from the head of the humerus Hand and forearm Supinated Neutral 49 Pad elbows, protruding objects i.e. fluid lines, stopcocks 50 Complications of Supine Pressure alopecia Prolonged immobilization of the head Cable connectors moved out of way Extra padding Periodic rotation of the head 51 Complications of Supine Backache Pts with kyphosis, scoliosis may require extra padding Pillow under knees Pad all bony prominences i.e. heels, sacrum 52 Complications of Supine Peripheral nerve injury Ulnar is the most common lesion in general No direct evidence that positioning or padding alone can prevent ulnar neuropathies Limit abduction to 2 hours) 61 Lithotomy Complications Compartment Syndrome Rare, but serious Occurs when perfusion to extremity is inadequate Results in ischemia, edema, and rhabdomyolysis Strongly related to surgical procedure time 62 Lateral Decubitus Surgeries involving the thorax, retroperitoneal structures or hip Anterior and posterior support Bedding rolls, braces or deflatable beanbag Arms positioned in front of patient Dependent arm on arm board Nondependent arm supported Arms should not abduct more than 90 degrees 63 Lateral Head/neck considerations Keep patient head in neutral position Excessive lateral rotation of neck can cause brachial plexus injury Dependent ear should be checked to avoid folding and pressure Eyes should be securely taped before positioning Eyes check frequently for external compression BAD GOOD 64 Axillary Roll Not really an “axillary roll” actually, it is a “chest roll”. Prevents compression of axillary artery and brachial plexus One liter fluid bag Place caudal to axilla Never in actual axilla 65 Lateral Monitor pulse in dependent arm Identifies compression to axillary neurovascular structures Kidney Rest Proper placement is under the dependent iliac crest Avoid compression of inferior vena cava Pad between knees 66 Ventilation while Lateral V/Q mismatch (ventilation/perfusion) Weight and pressure from mediastinum and abdominal contents on dependent lung=over inflation of nondependent lung - more ventilation in nondependent lung Gravity sends blood to dependent lung=more perfusion in dependent lung 67 Prone Surgeries to the posterior fossa of the skull, posterior spine, buttocks and perirectal area, and the lower extremities Pulmonary function may be superior to the supine or lateral positions if there is no significant abdominal pressure Weight borne by the bony structures or turned to the side 68 Prone- head and neck Head in neutral position Eyes, face and airway must be checked periodically Document checks Weight is borne only on bony structures Forehead and malar regions and chin No pressure on eyes, nose or mouth Many commercial head support systems Mirror System for head support 69 Prone- arms Arms may be tucked at sides in neutral position Arms may be on arm boards in “superman” position Maintain arm abduction less than 90 degrees Pad under elbows to protect ulnar nerve Wilson Frame 70 Prone- induction Induction and intubation takes place on the stretcher ETT is well secures Secretions may loosen tape and dislodge ETT Entire O.R. staff assists in move 71 Coordinating the move CRNA’s primary responsibility is coordinating the move and repositioning of the head Nobody moves until you count! Disconnect all lines and monitors except pulse oximetry Disconnect ETT from circuit Move head with one hand over face grasping ETT, the other hand supports the back of head 72 Prone- Rigid pin fixation This is the only instance where you are not in charge of the patient's head Surgeon holds the pin frame Any slippage or failure to secure bracketing device may lead to complication if the head suddenly drops 73 Prone- Abdomen Pressure on abdomen compromises respirations and transmits elevated venous pressure to abdominal and spine vessels, including the epidural veins Surgeon may request a decrease in blood pressure to facilitate surgical exposure- know your limits Weight is primarily supported by firm rolls or bolsters placed along each side from the clavicle to the iliac crest 74 Prone- Abdomen Minimizes abdominal compression Maintains normal pulmonary compliance Wilson frame, Jackson table are examples of specific prone O.R. tables 75 Prone- “pendulous structures” Male genitalia should be clear of compression Breasts should be placed medial to the bolsters Lower portion of each bolster or roll must be under iliac crest Prone Jack-knife Common position for rectal procedures Watch head and face as bed moves position 77 Accidental Extubation Make sure ETT is properly taped or tied to prevent accidental extubation Patients drip and drool secretions= tape gets wet and loose Don’t stick your hand under there without gloves! Would you consider an LMA if accidental extubation occurred while patient is prone and surgical site is open? 78 79 80 Sitting Used for surgery on posterior cervical spine and posterior fossa Advantages to the neurosurgeon Surgical exposure decreased blood in field Reduced perioperative blood loss Advantages to CRNA Access to the airway Reduced facial swelling Improved ventilation Disadvantages: Venous Air Embolism 81 Beach Chair Shoulder surgery Gravity will pull arms caudal Support the arms 82 Sitting Hemodynamic effects Pooling of blood in lower body Causes hypotension Compression stocking assist in venous return Control with IV fluids, vasopressors, and adjust anesthetic depth 83 For every inch in distance change of cuff position there is a 2 mm Hg rise or drop in mean arterial pressure. Blood Pressure while sitting Often in shoulder surgery while in the sitting position the surgeon “requests” hypotension – What will you do? In general, the approximate distance between the brain and the site of the BP cuff on the arm in the seated position will be 10-30 cm depending on the angle of the sitting position and the height of the patient. The brain MAP will be 8-24 mmHg lower than the measured mean brachial artery pressure. If the beach chair position is combined with the use of deliberate hypotension, cerebral perfusion may be severely compromised. 84 Venous Air Embolism Complications depend on The amount of air entrained Presence of patent foramen ovale 85 Air Embolism Patent Foramen Ovale Paradoxical embolism-air from venous circulation enters arterial circulation and results in stroke (cerebral circulation) or myocardial infarction (coronary circulation) 86 If small amount of air enters: It moves from the right atrium to the lungs and is absorbed into the alveoli and is probably not detected Venous Air Embolism If large amounts of air enter: Decreased in EtCO2 Pulse ox may drop due to a decrease in gas exchange in lungs Can see a decrease in cardiac output and BP 87 Venous Air Embolism Arrhythmia Desaturation Pulmonary hypertension Circulatory compromise Cardiac arrest 88 Fracture Table 89 Fracture Table 90 Nerves Brachial Plexus Ulnar Nerve Radial Nerve Median Nerve 91 Nerve Injury Serious perioperative complication Significant source of professional liability Three Mechanisms for injury Stretch Ischemia Compression The anesthetized patient cannot show early warning symptoms of pain, nor can reposition self spontaneously 92 ASA Closed Claims 93 Nerve Injury Nerve No. Closed Claims % of Total Ulnar 190 28 Brachial plexus 137 20 Lumbosacral 105 16 Spinal cord 84 13 Sciatic 34 5 Median 28 4 Radial 18 3 Femoral 15 2 Other 43 6 Miller, 2010 94 Ulnar Nerve Lies superficial at the elbow Injury results in inability to abduct or oppose the fifth finger Diminished sensation in fourth and fifth fingers 95 Ulnar Nerve The onset of symptoms frequently occurs more than 24 hours postop 70% in males 9% symptoms will be bilateral Very thin or obese at highest risk DM, alcoholism, smoking, cancer 96 Ulnar Nerve Injury Eventual atrophy of the intrinsic muscle of the hand Claw-like hand Despite adequate padding and precautions, still injured 97 Brachial Plexus Injuries result from stretching or compression Due to long superficial course in the axilla between two points of fixation: vertebra and axillary fascia Can occur during cardiac surgery during median sternotomy 98 Brachial Plexus Prevent Injury: Avoid arm abduction > 90 degrees Avoid lateral rotation of the head Avoid should braces Use non-sliding mattresses for extreme trendelenburg positioning 99 100 Brachial Plexus Innervation 101 Radial Nerve Innervates the posterior of first, second and third digits Primarily responsible for abduction of fingers Injury results in wrist drop Inability to abduct the thumb 102 Median Nerve May occur during IV needle insertion in antecubital fossa Nerve is close to medial cubital and basilic veins Unable to oppose 1st and 5th digits (Ape Hand) Decreased sensation over palmar surface of lateral 1-2 fingers Hand of Benediction 103 Median Nerve Injury Ape Hand- cannot bring 1st and 5th fingers together Hand of Benedictionwhen trying to make fist 104 Lower Extremity Nerves Sciatic Nerve Common Peroneal Nerve Femoral Nerve Obturator Nerve 105 Sciatic Risk of injury in lithotomy position Can be stretched with external rotation of the leg Hyperflexion of hips Extension of the knees 106 Sciatic Nerve Injury Weakness Tingling Burning Numbness 107 Common Peroneal Nerve Suitcase nerve Can be damaged from compression of nerve between the head of the fibula and frame of the leg support Foot drop Inability to extend toes dorsally 108 Femoral Nerve Lower abdominal surgeries d/t excessive retraction Injury manifests Decreased flexion of the hip Decreased extension of the knee Loss of sensation over superior aspect of the thigh and medial side of leg Weak knee 109 Obturator Nerve Forceps delivery Lower abdominal retractors Inability to adduct leg Decreased sensation over the medial side of thigh 110 Eye Injury Corneal abrasion is most common type of perioperative eye injury Direct trauma to cornea Facemasks Surgical drapes Other foreign objects Pt rubbing eyes 111 Prevent Corneal Abrasion Tape eyes early Watch your mask Avoid dangling objects/ watches Prevent patient from rubbing eyes upon awakening 112 Post-op Vision Loss (POVL) Rare but devastating Potential causes: Ischemic optic neuropathy (ION) Central retinal arterial occlusion 113 Post-op Vision Loss (POVL) Incidence of 0.056% More common in Spine and Cardiac Surgeries Check vision postoperatively when the patient is alert. Consider “staging” long spine surgeries. 114 POVL Perioperative factors: Prolonged hypotension Long duration of surgery Prone position Large blood loss Large crystalloid use Anemia Hemodilution Increased intraocular pressure 115 POVL Patient risk factors Hypertension Diabetes Atherosclerosis Morbid obesity Tobacco use 116 Avoid Avoid direct pressure on the eye to prevent CRAO Position Position the high-risk patient to ensure that the head is level with or higher than the heart, when possible. Position Position the high-risk patient without significant neck flexion, extension, lateral flexion, or rotation, when possible. Avoid Avoid external compression of the abdomen or chest. ASA Positioningrelated recommendations 11 7 65 year old male Cystoscopy, bilateral ureteral stent placement POVL Case study 1 Laparascopic bilateral pelvic lymph node dissection Laparascopic radical prostatectomy 16.5 hour procedure Trendelenburg dorso-lithotomy position 11 8 Pre-op Past retinal detachment History (repaired) Cataract Case Study 1 Primary open angle glaucoma OS with glaucomatous optic neuropathy Pre-op visual acuity of 20/20 OD, 20/50 OS 11 9 Intra-operative course Case Study 1 After anesthetic induction, blood pressure dropped to 80/50 for 30 minutes. Otherwise BP maintained 110-130/70-80 mmHg Blood loss 500 mL Post op HCT 38.3 No known operative or anesthetic complications 12 0 Post Op exam c/o vision loss OD upon awakening Case Study 1 Visual acuity 20/40 OD, 20/60 OS Mild punctate corneal erosions OD Significant facial and periorbital edema Partial vision field loss remained OD 12 1 ASA Practice Advisory For “high risk” patients undergoing complex spine surgery: Stage surgery if possible Keep head neutral Use colloids along with crystalloids Inform patient of risk “Frequent” eye checks no official time frame referenced (Dr. Oakes recommends Q5 min). 12 2 POVL- Case Study 2 22 year old female Right laparoscopic pyeloplasty for ureteropelvic junction obstruction 6 hour surgery BP 100/45 after induction, 100-110/50-60 duration of case Blood loss 50 mL Post op HCT 34.2 Significant facial and periorbital edema 123 Case Study 2 Post-op status Immediately noted bilateral loss of vision Initially attributed to “residual anesthesia” Visual disturbance continues POD 7 Ophthalmology consult Diffuse peripheral depression OD Brain and orbit MRI normal 124 Evaluation of Neuropathies Motor Electromyogram Determines the exact location of the injury Records the electrical activity of muscle from a needle electrode inserted within it. Nerve conduction studies Assess both motor and sensory nerves Measures the size of the muscle action potential Provides an estimate of the number of motor axons and muscle fibers that are activated by the stimulus 125 Treatment of Neuropathies Neurologist consult in stages (first week, 4 weeks postop, 12 weeks postop, etc.) Most sensory neuropathies are transient and require only reassurance Most motor neuropathies include demyelination of peripheral fibers Physical therapy is recommended to prevent contractures and muscle atrophy 126 Conclusion Remember, the final position should be a position that the patient would comfortably tolerate if awake. 127 References Miller, R. D. (2015). 41, Patient Positioning and Anesthesia. Miller's Anesthesia (7th ed., ). Philadelphia, PA: Churchill Livingstone. Roth, S. Perioperative visual loss: what do we know, what can we do?. British Journal of Anaesthesia, 103, i31-i40. Barash, P. (2017). Clinical anesthesia (8th ed.). Philadelphia: Lippincott Williams & Wilkins. 128