Anesthesia for Head and Neck Surgery

ANESTHESIA FOR HEAD AND NECK SURGERY

INTRODUCTION

  • Collaboration Requirement: Emphasizes the need for close cooperation and communication between the surgeon and anesthesia provider.

  • Airway Challenges: Many anomalies treated in head and neck surgery present significant challenges for the establishment and protection of the airway.

  • Types of Surgery: Includes surgeries for various conditions such as:

    • Thyroid disease

    • Cancer

    • Congenital disease

    • Trauma

  • Specific Surgical Procedures:

    • Thyroidectomy

    • Parathyroidectomy

    • Tracheostomy

    • Laryngectomy

    • Radical neck dissection

    • Facial trauma

THYROIDECTOMY

  • Definition: A thyroidectomy is the partial or complete surgical removal of the thyroid gland or masses within it.

  • Types of Thyroidectomy:

    • Subtotal thyroidectomy: Performed based on clinical indications.

  • Steps of the Procedure:

    • Exposure of the gland

    • Devascularization of the thyroid

    • Resection of the affected tissue

    • Closure of the surgical site

INDICATIONS FOR THYROIDECTOMY

  • Indications include:

    • Nodule suspicious for malignancy

    • Positive or suspicious needle biopsy results

    • Presence of thyroid mass causing vocal cord paralysis

    • Compression of the respiratory and digestive tracts

    • Nodule extending into the mediastinum

    • Grave’s disease or hyperfunctioning nodule unresponsive to non-surgical treatment

    • Metastatic thyroid carcinoma

GOITER

  • Description: A multinodular enlarged thyroid gland is typically referred to as a goiter, which is the most common non-neoplastic thyroid mass.

  • Resection Criteria: Surgical resection is indicated when a goiter:

    • Causes compression (dysphagia or dyspnea)

    • Extends into the mediastinum

    • Is cosmetically unappealing.

  • Difficult Intubation: Documented in 5-8% of patients with goiter, highlighting the potential need for special anesthesia considerations.

HYPERTHYROIDISM

  • Definition: Hyperthyroidism is characterized by the overproduction of triiodothyronine (T3) and/or thyroxine (T4).

    • Laboratory Findings: Increased serum T3 and T4 levels with a normal or lowered TSH level.

    • Hormone Activity: T3 is the biologically active thyroid hormone, with T4 at 90% and T3 at 10% of the hormones secreted by the thyroid gland.

  • Conversion: Most of T4 is converted to T3 in peripheral tissues.

  • Collective Term: Disorders of increased thyroid hormone concentrations are referred to collectively as thyrotoxicosis.

  • Symptoms:

    • Anxiety, fatigue, tremor, weakness

    • Tachycardia, heat intolerance, exophthalmia

  • Common Causes of Hyperthyroidism:

    • Grave’s disease (90% of cases)

    • Characterized by a diffuse toxic goiter with autoimmune etiology

    • Iatrogenic causes from thyroid hormone therapy for hypothyroidism

    • Toxic nodular goiter

    • Thyroiditis and thyroid adenomas

MANAGEMENT OF HYPERTHYROIDISM

  • Medications:

    • Anti-thyroid drugs: Inhibit hormone synthesis e.g. propylthiouracil, methimazole, carbimazole.

    • Beta-adrenergic antagonists: Reduce the peripheral conversion of T4 to T3 and regulate effects of T3 and T4 on target tissues.

    • Inorganic iodine and lithium: Used to inhibit the release of T3 and T4.

    • Glucocorticosteroids: Support T3 and T4 function and provide immunosuppression.

HYPERTHYROIDISM - PRE-OP CONSIDERATIONS

  • Medications: Continue anti-thyroid agents and beta-blockers preoperatively.

  • Cardiac Assessment: Recommended due to chronic effects of thyrotoxicosis, as 10% of patients may develop atrial fibrillation.

  • Physiological Changes: Increased blood volume, decreased peripheral resistance, and widened pulse pressure can result in increased CO, HR, and SBP.

  • Routine Labs: Baseline electrolytes, thyroid function tests, and a chest X-ray may be warranted due to potential intrathoracic extension of masses.

    • CT, MRI, and/or pulmonary function tests may be required for lesions indicating airway obstruction.

  • Airway Assessment: Check for deviation, compression, or narrowing. Look for signs of orthopnea, dyspnea, stridor, or hoarseness.

  • Substernal Extension Consideration: Important anesthetic implications include potential for tracheal compression post muscle relaxation.

  • Euthyroid State: Optimal for non-urgent procedures is with SBP < 140 mmHg and HR < 100 bpm.

HYPERTHYROIDISM - PRE-OP CONTINUED

  • Assessment of RLN: Evaluate integrity of the recurrent laryngeal nerve, which may be impacted by compression from thyroid masses.

    • Indicators of RLN issues include hoarseness, weak voice, and difficulty in phonation (ask patient to say ‘e’).

  • Physical Examination: To assess thyroid gland size and its relationship to the surrounding structures such as the trachea.

ANESTHESIA FOR THYROIDECTOMY

  • Extensive Resections: In cases involving extensive resections or repeat procedures, monitoring of nerve action potentials using either surface Recurrent Laryngeal Nerve monitors or Nerve Integrity Monitors (NIM) suitable for endotracheal tubes might be needed.

    • NIM tubes have embedded electrodes, placed under direct visualization to ensure contact with the vocal cords.

  • Standard Monitors: Required during procedures include temperature monitors since an increase may indicate a thyroid storm.

  • IV Access:

    • At least 1-2 peripheral IVs, with larger bore access recommended for extensive disease, especially with substernal involvement.

    • An arterial line may be necessary for significant substernal resections.

  • Eye Protection: Use taping and lubrication to minimize risk of corneal abrasions due to exophthalmos.

ANESTHESIA FOR THYROIDECTOMY - INDUCTION

  • Induction Agents:

    • Avoid using ketamine due to sympathomimetic effects; instead, use hypnotics of choice.

    • Use lidocaine and beta-blockers to blunt sympathetic response during direct laryngoscopy.

    • Avoid long-acting muscle relaxants if intraoperative monitoring occurs.

ANESTHESIA FOR THYROIDECTOMY - MAINTENANCE

  • Hypotension Management: Use direct-acting agents such as phenylephrine.

    • Indirect-acting agents, like ephedrine, should be avoided as they provoke catecholamine release.

  • Thyrotoxic Crisis Monitoring:

    • Watch for signs of a thyrotoxic crisis due to abrupt T3 and T4 release, often referred to as a “thyroid storm.”

    • Typically occurs during the intraoperative period following manipulation of the thyroid gland, usually 6-18 hours post-surgery.

ANESTHESIA FOR THYROIDECTOMY - EMERGENCE

  • Reversal Monitoring: Ensure complete reversal of neuromuscular blockade.

  • Coughing Management: Use narcotics or lidocaine judiciously to attenuate bucking or coughing.

  • Vocal Cord Monitoring: Historically, direct laryngoscopy was utilized for assessing vocal cords before awakening; this practice has decreased with the advent of nerve integrity monitoring, yet vocal cord function must be monitored upon emergence.

THYROID STORM

  • Definition: An extreme acceleration of thyrotoxicosis in a patient who is either undiagnosed or inadequately treated.

  • Symptoms:

    • Fever > 38.5°C, tachycardia, confusion, agitation, tremors, weakness, dysrhythmias, nausea/vomiting, hypertension, heart failure.

  • Differential Diagnosis: Includes malignant hyperthermia, pheochromocytoma, neuroleptic malignant syndrome, and light anesthesia.

  • Management:

    • Administer cooled IV fluids, utilize cooling blankets, ice packs, and reduce room temperature.

    • Use continuous infusion of Esmolol to maintain HR < 100 bpm.

    • Consider antithyroid drugs if appropriate and administer hydrocortisone (100-200 mg IV) for refractory hypotension.

    • Caution: Do not use aspirin as it may displace T3 and T4 from carrier proteins.

THYROIDECTOMY: POST-OP CONSIDERATIONS

  • Complications:

    • Risk of airway compromise from hematoma, mucosal edema, tracheomalacia, or RLN damage.

    • Hypoparathyroidism leading to hypocalcemia.

    • Monitor signs of RLN injury:

    • Unilateral RLN Paralysis: Presents as hoarseness with minimal airway obstruction.

    • Bilateral RLN Paralysis: Results in respiratory obstruction when the true vocal cords are in a paramedian position - a medical emergency!

PARATHYROID GLANDS

  • Function: The parathyroid glands (4-8 in number) maintain calcium levels in the body through the release of parathyroid hormone (PTH), which is crucial for calcium and phosphate homeostasis.

  • Hyperparathyroidism: Excessive secretion of PTH causing serious calcium imbalances, primarily recognized by elevated serum PTH levels despite higher serum calcium.

HYPOPARATHYROIDISM

  • Characteristic Features: Denoted by low PTH levels or resistance to the effects of PTH. Low calcium levels indicated by:

    • Ionized calcium < 4.5 mg/dL

    • Serum calcium < 8.5 mg/dL

  • Causes:

    • Most commonly results from inadvertent removal of the parathyroid glands during surgeries or damage to their blood supply.

  • Other Causes: Genetic conditions, irradiation, trauma, severe magnesium deficiency due to alcohol abuse, poor nutrition or malabsorption, and acute hypermagnesemia.

  • Treatment: Involves the use of activated Vitamin D, calcium supplementation, and magnesium replacement if indicated.

SIGNS AND SYMPTOMS OF HYPOCALCEMIA

  • Symptoms include abdominal cramps, Chvostek sign, Trousseau sign, laryngeal muscle spasms, hyperreflexia, perioral paresthesias, numbness, prolonged QT interval, hypotension, decreased cardiac contractility, and neuromuscular excitability leading to spasms, cramps, and potentially seizures.

HYPERCALCEMIA

  • Epidemiology: Hyperparathyroidism and malignancies account for 90% of hypercalcemia cases.

    • Patients usually remain asymptomatic until total serum calcium > 12 mg/dL.

    • Severe hypercalcemia (> 14 mg/dL) is life-threatening requiring immediate intervention.

  • Clinical Implications: Extreme osteoclast activity can lead to painful bones and increased risk of fractures. Chronic hypercalcemia can cause systemic complications:

    • Pancreatitis, nephrolithiasis, nephrocalcinosis, polyuria, hypertension, peptic ulcers, etc.

    • Commonly summed up as “bones, stones, and groans.”

SIGNS AND SYMPTOMS OF HYPERCALCEMIA

  • Include skeletal muscle weakness, polyuria and polydipsia, kidney stones, anemia, prolonged PR interval, short QT interval, vomiting, systemic hypertension, abdominal pain, peptic ulcers, pancreatitis, skeletal demineralization, somnolence, decreased pain perception, and psychosis.

MANAGEMENT OF HYPERPARATHYROIDISM

  • Fluid Management: IV fluid replacement with saline loop diuretics which inhibit sodium and calcium reabsorption.

  • Life-threatening Hypercalcemia Treatments:

    • Bisphosphonates (e.g. disodium etidronate), mithramycin, glucocorticoids, hemodialysis.

    • Calcitonin offers rapid but transient reduction of calcium levels.

  • Surgical Management: For adenomas, malignancies, or hyperplasia, surgical excision of all parathyroid tissue except for some of one gland is the treatment of choice. For total parathyroidectomies, a portion of the parathyroid gland may be implanted in musculature, such as the arm, to prevent postoperative hypocalcemia.

PARATHYROIDECTOMY - ANESTHESIA

  • Preoperative Preparation: Assess for clinical signs of hypercalcemia focusing on renal, cardiac, and CNS symptoms. Conduct routine labs including ionized calcium and magnesium, and perform an EKG to evaluate for prolonged PR and short QT intervals.

  • Intraoperative Techniques: General anesthesia with ETT is typically indicated. Position the patient supine with their arms tucked and head hyperextended with a roll for optimal access.

    • Use of intraoperative monitoring of serum PTH might be requested as resection approaches completion; this can be done through a saline lock or arterial line.

    • Anticipate variation in muscle relaxant response; patients may show sensitivity to succinylcholine and resistance to non-depolarizing muscle relaxants (NDMR).

  • Postoperative Complications: Include recurrent laryngeal nerve injury, bleeding, transient or complete hypoparathyroidism.

TRACHEOSTOMY

  • Definition: Surgical incision of the trachea to create a temporary or permanent airway opening. "Tracheostomy" and "tracheotomy" are often used interchangeably.

    • Typically, incision occurs between the 3rd, 4th, and 5th tracheal rings.

INDICATIONS FOR TRACHEOSTOMY

  • Non-Emergent Situations:

    • Prolonged intubation

    • Preoperative airway establishment for extensive head and neck procedures

    • Chronic aspiration in patients with vocal cord paralysis.

  • Emergency Situations:

    • Patients with severe head, neck, or facial trauma.

    • Consideration for cricothyrotomy may arise in life-threatening emergencies requiring rapid airway establishment (in 1-2 minutes).

TRACHEOSTOMY - PRE-OP CONSIDERATIONS

  • Patient Transport: Patients requiring extended intubation must be sedated and paralyzed during OR transport. Emergency intubation drugs and equipment need to be at hand.

    • Coordination among the perioperative team is essential for safe transport and monitoring.

  • Preoperative Assessments:

    • Evaluate need for suctioning, obtain baseline ABGs and chest X-ray before transfer.

    • Transport ICU ventilator when necessary, ensuring compatible ventilation strategies during operations.

TRACHEOSTOMY - ANESTHESIA METHODS

  • A range of anesthetic techniques may be employed.

    • Local anesthesia requires patient cooperation and often involves infiltration supplemented with a bilateral superficial cervical plexus block.

    • Alternatively, general anesthesia may be administered, typically requiring neuromuscular blockade to prevent coughing during surgery.

  • Emergency Preparedness: The anesthetist should examine the airway post-anesthesia induction and prepare for potential reintubation.

  • Oxygen Management: N2O and O2 mixtures can be used until the trach tube insertion is imminent, at which point 100% O2 should be employed, reducing concentrations to minimize fire risk.

TRACHEOSTOMY - ANESTHESIA ROUTINE PROTOCOLS

  • Surgical Steps and Corresponding Anesthesiologist Actions:

    1. Tracheal Entry Prep: Surgeon prepares to enter trachea; anesthesiologist ready to deflate ETT cuff.

    2. Tracheal Transection: Surgeon transects trachea and expands the opening; anesthesiologist withdraws the ETT accordingly.

    3. Tube Placement: Surgeon places tracheostomy tube; anesthesiologist connects the circuit to the tracheostomy tube ensuring a flexible connection for ease of maneuverability and reduction of tension.

  • Verification and Adjustment: After placement, verify trach tube placement using ETCO2 waveform and bilateral breath sounds, then reestablish preoperative ventilator settings, especially if the patient is ventilator-dependent.

TRACHEOSTOMY - POST-OP COMPLICATIONS

  • Risks: Include pneumothorax, subcutaneous emphysema, pneumomediastinum, hemorrhage, cardiac tamponade, and improper placement of the trach tube.

  • Patient Transfer: Ensure safe transfer back to ICU or PACU, making sure emergency medications and airway equipment are on hand.

  • Cuff Pressure Monitoring: Important to prevent ischemic tracheal injury as the tracheostomy tract stabilizes over the next 5 days.

LARYNGECTOMY

  • Types:

    • Supraglottic Laryngectomy: Resection includes the larynx to the base of the tongue, retaining true vocal cords. This procedure typically leaves the patient with normal phonation and airway post-operation with temporary tracheostomy for 4-6 weeks.

    • Partial Laryngectomy: Involves removal of a part of the larynx, preserving phonatory and swallowing functions while reducing the need for a permanent tracheostomy.

    • Total Laryngectomy: Involves complete removal of the larynx, hyoid bone, and a portion of the tongue with significant surgical exposure from hyoid to clavicle, resulting in voice loss and necessitating breathing through a trach tube.

LARYNGECTOMY - PRE-OP CONSIDERATIONS

  • Patient Demographics: Typically involves elderly patients with histories of alcohol/tobacco use, with common comorbidities like bronchitis, emphysema, and cardiovascular disease.

  • Preoperative Testing: Importance of respiratory function evaluation through ABGs, PFTs, and chest X-ray to detect potential CO2 retention and hypoxemia.

    • Investigate tumor-related issues affecting eating, like weight loss or malnutrition.

    • Airway assessment can reveal deviations from norm due to edema or tumor presence, necessitating meticulous preoperative review including lateral radiological studies.

LARYNGECTOMY - ANESTHESIA STRATEGY

  • Monitoring Requirements: Include standard and advanced monitors such as arterial or central lines as dictated by patient condition.

    • General anesthesia with endotracheal intubation is typically utilized, with readiness for difficult intubation preparation.

  • Anticipated Surgical Positioning: Take into account the potential for table rotation; reverse Trendelenburg can aid in hemorrhage control.

    • Outline muscle relaxation strategies, particularly in relation to facial nerve monitoring requests from surgical teams.

  • Complications During Dissection: Awareness of potential complications, such as hypotension from carotid sinus manipulation and venous air embolism, which require immediate management.

LARYNGECTOMY - POST-OP MANAGEMENT

  • Postoperative Care: Importance of providing effective analgesia and assessing for neuromuscular reversal prior to ICU transfer, keeping traditional ventilatory supports in mind post-operatively.

  • Common Complications: Include nerve injuries (facial nerve leading to droop, phrenic nerve causing diaphragmatic paralysis), pneumothorax from low neck dissection, and airway distress due to tight dressing or hematoma.

RADICAL NECK DISSECTION (RND)

  • Indication: Performed for local tumor invasion, involving complete cervical lymphadenectomy and resection of the sternocleidomastoid (SCM), internal jugular vein (IJV), and specific cranial nerves.

  • Surgical Variations: All neck dissections may correspond with resections of tongue, pharynx, or larynx; modified versions exist preserving certain anatomical structures.

RND - RECONSTRUCTION

  • Post-surgical reconstruction may involve:

    • Using regional pedicle flaps and microsurgical techniques.

    • Potential options include flap harvesting from pectoralis major, trapezius, or cadaver bone for mandible reconstruction.

RND - ANESTHESIA DETAILS

  • Similar to Laryngectomy Protocols: Awareness that uncontrolled bleeding may occur from the internal jugular vein at the skull's base.

    • Muscle relaxants may need careful consideration because of nerve monitoring by the surgery team, particularly CN XI.

  • Fluid Management: Careful balance is needed to prevent overhydration which can lead to flap issues, emphasizing the need to maintain normothermia.

RND - POST-OP CONCERNS

  • Typical complications: hematoma, painful shoulder syndrome, skin flap necrosis, cranial and phrenic nerve injurious effects.

FACIAL FRACTURES

  • Caused by blunt force trauma affecting airway, vision, and cranial integrity; classified using the LeForte system.

  • Clinical Presentation:

    • Symptoms might include breathing difficulties through the nose, alterations in sensation, swelling, double vision, facial lacerations, and missing teeth.

LEFORTE FRACTURES

  • LeFort I: A dental-alveolar fracture, minimally affecting airway, allowing oral or nasal intubation.

  • LeFort II: Characterized by pyramidal fracture where nasal intubation is mostly contraindicated.

  • LeFort III: A major disjunction separating mid-facial skeleton from cranial base, typically requiring an awake tracheostomy for airway security.

FACIAL FRACTURES - PRE-OP ASSESSMENTS

  • Systemic Health Evaluation: Including mental status, substance use, food/liquid intake, and spinal or intracranial injury recognition, enabling careful airway management and examination for significant edema from trauma.

FACIAL FRACTURES - ANESTHESIA STRATEGIES

  • Provided patients remain hemodynamically stable, use IV induction with nasal RAE tube for surgical access.

    • Consider head tilt techniques to mitigate intraoperative bleeding.

  • Emergence Techniques: Exercise caution in postoperative extubation; signs of swelling may necessitate withholding extubation.

FACIAL FRACTURES - POST-OP CONSIDERATIONS

  • Ensure intubated patients are adequately sedated to prevent unintended extubation; wire cutters should be readily available if wires are used post-operatively.

    • Prophylaxis for nausea/vomiting should be addressed due to the emetogenic potential of blood ingestion.

CONCLUSION

  • Summary of critical information on anesthesia considerations for various head and neck surgical procedures, emphasizing collaboration, communication, patient safety, and proactive management of potential complications.