H & N

ANESTHESIA FOR HEAD AND NECK SURGERY

Presented by: Elisha Coppens DNAP, MPHARM, CRNA, CHSE, COI

INTRODUCTION

  • Close cooperation and communication between surgeon and anesthesia provider is crucial for ENT procedures, including head and neck surgery.
  • Challenges in airway management due to various anomalies requiring surgical intervention in this area.
  • Types of surgeries included:
    • Thyroid surgery
    • Surgery for thyroid disease
    • Cancer surgery
    • Congenital disease surgical intervention
    • Trauma surgery: Various types listed below including, but not limited to:
    • Thyroidectomy
    • Parathyroidectomy
    • Tracheostomy
    • Laryngectomy
    • Radical neck dissection
    • Facial trauma surgical management

THYROIDECTOMY

  • Definition: A surgical procedure involving the partial or complete removal of the thyroid gland or masses within it.
  • Subtotal thyroidectomy may be performed based on specific indications.

Steps of Thyroid Removal

  1. Exposure
  2. Devascularization
  3. Resection
  4. Closure

INDICATIONS FOR THYROIDECTOMY

  • Nodule suspicious for malignancy.
  • Positive or suspicious needle biopsy findings.
  • Presence of a thyroid mass causing vocal cord paralysis.
  • Compression of respiratory and digestive tract.
  • Nodule extending into the mediastinum.
  • Grave's disease or hyperfunctioning nodule unable to be controlled through non-surgical methods.
  • Metastatic thyroid carcinoma detected.

GOITER

  • Defined as the most common non-neoplastic thyroid mass; characterized by a multinodular enlarged thyroid gland.
  • Surgical intervention indicated when it causes compression symptoms, including dysphagia or dyspnea, has mediastinal extension, or presents cosmetic concerns.
  • Notably, difficult intubation occurs in 5-8% of goiter patients.

HYPERTHYROIDISM

  • Definition: Hyperthyroidism is characterized by the overproduction of triiodothyronine (T3) and/or thyroxine (T4) hormones.
  • Laboratory findings: Elevated serum T3 and T4 levels with decreased or normal TSH levels.
  • T3 is the biologically active thyroid hormone, composed of 90% T4 and 10% T3. Most T4 is converted to T3 in peripheral tissues.
  • Collectively, disorders characterized by increased thyroid hormones are referred to as thyrotoxicosis.
  • Signs and Symptoms (S/S) include:
    • Anxiety
    • Fatigue
    • Tremors
    • Muscle weakness
    • Tachycardia
    • Heat intolerance
    • Exophthalmus (bulging eyes).

Common Causes of Hyperthyroidism

  1. Grave's Disease:
    • Most common cause (90%).
    • Features a diffuse toxic goiter and likely autoimmune etiology.
  2. Iatrogenic causes from treatment of hypothyroidism with thyroid hormones.
  3. Toxic nodular goiter, thyroiditis, and thyroid adenomas.

MANAGEMENT OF HYPERTHYROIDISM

  • Utilization of anti-thyroid medications to inhibit hormone synthesis such as:
    • Propythiouracil
    • Methimazole
    • Carbimazole
  • Beta-adrenergic antagonists can decrease peripheral conversion of T4 to T3 and augment effects of T3 and T4 at organ and tissue levels.
  • Inorganic iodine and lithium serve to inhibit the release of T3 and T4.
  • Glucocorticosteroids help improve actions of T3 and T4 while offering immunosuppressive effects.

PRE-OP MANAGEMENT OF HYPERTHYROIDISM

  • Continue all medications including anti-thyroid drugs and beta-blockers.
  • Cardiac work-up recommended as 10% of patients may have atrial fibrillation due to chronic hyperdynamic effects of thyrotoxicosis on the heart.
  • Typical laboratory findings: Increased blood volume, decreased peripheral resistance, with predictable increases in cardiac output, heart rate and systolic blood pressure.
  • Routine labs before surgery should include baseline electrolytes and thyroid function tests (TFT), along with CXR to evaluate any intrathoracic extension of disease.
  • Imaging such as CT, MRI, or PFTs may be required for airway assessments where lesions present potential obstruction.
    • Symptoms to assess: Orthopnea, dyspnea, stridor, wheezing or hoarseness.
  • Special considerations for substernal thyroid extensions due to potential for unanticipated tracheal compression during anesthesia.
  • An optimal pre-op state is euthyroid with systolic blood pressure <140 and heart rate <100 for non-urgent procedures.

FURTHER PRE-OP CONSIDERATIONS

  • Evaluate integrity of the recurrent laryngeal nerve (RLN) which may be compressed by thyroid masses.
  • Signs such as hoarseness, weak voice, difficulties in phonation (prompt patient to say 'e'), or aphonia can indicate RLN issues.
  • The physical exam should include palpation of the thyroid gland, assessing size and its relationship to the trachea.

ANESTHESIA FOR THYROIDECTOMY

  • In extensive resections, or for total thyroidectomy, monitoring of nerve action potentials may be done with either a surface RLN monitor or with a nerve integrity monitor (NIM) endotracheal tube.
    • The NIM ETT features embedded electrodes and should be placed under direct visualization ensuring bilateral true vocal cords contact with the electrodes.
    • Anode or reinforced ETTs may be necessary for minimizing risks of kinking or obstruction with the added benefit of a spiral support of metal or nylon.
  • Standard monitoring practices to be adhered to.
  • Any temperature elevation intraoperatively may indicate a thyroid storm.
  • IV access ideally includes 1-2 peripheral IVs, noting that access may be limited due to the positioning of the arms.
    • Larger bore IVs are preferred for extensive disease or substernal involvement, with consideration of an arterial line based on surgical extent.
  • Eyes should be protected with tape and lubrication to mitigate risks of corneal abrasions and dryness, especially in exophthalmic patients.

INDUCTION FOR THYROIDECTOMY

  • Avoid ketamine due to sympathomimetic responses; alternative hypnotics should be employed.
  • Lidocaine, beta-blockers, and judicious narcotic use can help blunt sympathetic response during laryngoscopy.
  • Long-acting muscle relaxants should be avoided if intraoperative monitoring is planned.

MAINTENANCE ANESTHESIA

  • Hypotension should be addressed with direct-acting agents like phenylephrine.
  • Avoid indirect-acting agents such as ephedrine as these can provoke catecholamine release.
  • Continuous monitoring for signs of thyrotoxic crisis due to abrupt T3 and T4 release is crucial; cases of "thyroid storm" can happen anytime during hyperthyroid state.
  • Increased incidence reported 6-18 hours post-surgery; vigilance is paramount during this timeframe.

EMERGENCE FROM ANESTHESIA

  • Full reversal of neuromuscular blockade is essential.
  • Caution with anticholinergics as atropine can have a stronger chronotropic effect compared to glycopyrrolate.
  • Control bucking and coughing with careful narcotic or lidocaine use.
  • Historically, vocal cord function was assessed pre-awakening by direct laryngoscopy, but the advent of NIM has reduced this practice.
  • Ongoing monitoring of vocal cord function is critical upon emergence from anesthesia.

THYROID STORM

  • Defined as an extreme exacerbation of thyrotoxicosis induced by acute stress in previously undiagnosed or inadequately treated hyperthyroid patients.
    • Features metabolic acidosis due to increased lactate production.
  • Signs and Symptoms include:
    • Fever >38.5°C
    • Tachycardia
    • Confusion
    • Agitation
    • Tremors
    • Muscle weakness
    • Dysrhythmias
    • Nausea and vomiting
    • Hypertension
    • Heart failure
  • Differential diagnosis to be considered encompasses:
    • Malignant Hyperthermia (MH)
    • Pheochromocytoma
    • Neuroleptic Malignant Syndrome
    • Inadequate anesthesia levels
  • Management includes:
    • IV fluids for cooling, cooling blankets, ice packs, and room temperature reduction.
    • Administer continuous Esmolol infusion to maintain heart rate <100 bpm.
    • Antithyroid drugs may prove beneficial.
    • In refractory hypotensive cases, Hydrocortisone 100-200 mg IV can be used.
    • Do NOT use Aspirin (ASA) as it may free T3 and T4 from carrier proteins, exacerbating the condition.

THYROIDECTOMY: POST-OP COMPLICATIONS

  • Post-operative concerns include:
    • Potential airway compromise from hematoma or mucosal edema.
    • Tracheomalacia and recurrent laryngeal nerve (RLN) injury presents risks.
  • Monitor for complications including:
    • Unilateral RLN paralysis: Characteristic hoarseness with minimal obstruction.
    • Bilateral RLN paralysis: Results in severe respiratory obstruction - a medical emergency.

PARATHYROID GLANDS

  • Parathyroid glands (typically 4-8) maintain calcium levels within the body range, releasing parathyroid hormone (PTH), crucial for calcium and phosphate homeostasis.
  • Hyperparathyroidism arises from excessive PTH secretion causing calcium imbalance.
    • Primary hyperparathyroidism is diagnosed via elevated serum PTH levels alongside high serum calcium.

HYPOPARATHYROIDISM

  • Characterized by low PTH levels or resistance to PTH effects.
  • Criteria: Ionized calcium <4.5 mg/dL or serum calcium <8.5 mg/dL.
  • Causes include inadvertent removal or damage during surgeries, hereditary conditions, or deficiencies linked to nutrition or trauma.
  • Management includes activated vitamin D and calcium supplementation, and magnesium if necessary.

SIGNS & SYMPTOMS OF HYPOCALCEMIA

  • Symptoms include:
    • Abdominal cramps
    • Chvostek's sign
    • Trousseau's sign
    • Laryngeal muscle spasms
    • Hyperreflexia
    • Paresthesia (perioral)
    • Acral numbness
    • Prolonged QT interval
    • Hypotension
    • Decreased cardiac contractility
    • Increased neuromuscular excitability (spasms, cramps, tetany, seizures).

HYPERCALCEMIA

  • Majority of cases arise from hyperparathyroidism and cancer.
  • Many patients remain asymptomatic until total serum calcium exceeds 12 mg/dL.
  • Severe cases (>14 mg/dL) require urgent care due to potential life-threatening implications.
    • Results in bone pain from osteoclast activity and multi-organ complications.
  • Typical manifestations include:
    • Musculoskeletal pain ("bones, stones, and groans")
    • Kidney issues (nephrolithiasis)
    • Peptic ulcers in the stomach
    • HTN, cardiac issues (arrhythmias), and systemic manifestations.

SIGNS & SYMPTOMS OF HYPERCALCEMIA

  • Indicators include:
    • Skeletal muscle weakness
    • Polyuria and polydipsia
    • Kidney stones
    • Anemia
    • Prolonged PR interval
    • Shortened QT interval
    • Nausea and vomiting
    • Abdominal pain
    • Pancreatitis and skeletal demineralization
    • Psychosis or altered consciousness.

MANAGEMENT OF HYPERPARATHYROIDISM

  • Lifesaving interventions include:
    • IV fluid replacement with saline and loop diuretics.
    • Treatment options for severe hypercalcemia involve:
    • Bisphosphonates (e.g. disodium etidronate)
    • Mithramycin
    • Glucocorticoids
    • Hemodialysis if warranted
    • Calcitonin for rapid decrease in calcium levels (effects are short-lived).
  • Surgical approaches focus on excising adenomas, malignancies, or hyperplastic tissue, conserving some tissue when possible.

PARATHYROIDECTOMY ANESTHESIA

Preoperative

  • Evaluate for hypercalcemia, including renal, cardiac, and CNS symptoms using routine labs and ionized calcium values.
  • Monitor EKG for prolonged PR interval or shortened QT interval and adjust perioperative approach accordingly.

Intraoperative

  • Standard monitors apply, with typically general anesthesia via ETT unless otherwise indicated.
  • Positioning with arms tucked, hyperextended head to facilitate access.
  • Adjust the OR table to mitigate bleeding risk and avoid vertebral compression from osteoporotic changes.

Intraoperative Continued

  • Monitor serum levels of PTH intraoperatively for resection assessments.
  • Recognize potential altered responses to muscle relaxants, especially sensitivity to succinylcholine and resistance to non-depolarizing muscle relaxants.
  • Involve nerve monitoring as needed, maintaining clear communication with the surgical team.

Postoperative Complications

  • Look out for:
    • Recurrent laryngeal nerve injuries
    • Hemorrhage
    • Transient or permanent hypoparathyroidism

TRACHEOSTOMY

  • Description: A surgical incision in the trachea creating a temporary or permanent opening. Defined interchangeably as tracheostomy/tracheotomy.
  • Standard incision is conducted through the 3rd, 4th, or 5th tracheal rings.

INDICATIONS FOR TRACHEOSTOMY

Non-Emergent
  • Prolonged intubation scenarios.
  • Preoperative airway establishment for significant head/neck procedures.
  • Chronic aspiration management (e.g. vocal cord paralysis).
Emergent
  • Extensive trauma lacerations to the head, neck, or face.
  • Note: A cricothyrotomy might be performed alternatively for more rapid airway access (1-2 minutes).

TRACHEOSTOMY PRE-OP MANAGEMENT

  • Transport intubated patients to the OR with adequate sedation and paralysis.
  • Ensure readiness of emergency intubation supplies during transport.
  • Coordination with the perioperative team is vital for safe transport especially for patients with ventilatory needs.
  • Routine pre-op assessments should include suctioning needs, baseline ABG knowledge, and CXR evaluations.
  • For ventilator-dependent patients with high peak inspiratory pressures, ICU ventilators should be considered for transport.

TRACHEOSTOMY ANESTHESIA

  • Techniques range from local anesthesia (patient cooperation required) to general anesthesia with muscle blockade.
  • If local, infiltration supplemented with a bilateral superficial cervical plexus block may suffice.
  • General anesthesia typically involves induction via inhalation or IV methods, often employing paralysis to mitigate coughing.
  • Once anesthesia is achieved, a direct laryngoscopy should happen to assess airway in case reintubation is necessary.

TRACHEOSTOMY ANESTHESIA CONTINUED

  • Use of N2O:O2 is permissible until tracheostomy tube placement is imminent, with careful oxygen management to mitigate airway fire risks.
  • Ensure hand ventilation during the tube's placement unless contraindicated by ventilatory parameters.

TRACHEOSTOMY PROCEDURE SEQUENCE

Surgeon ActionAnesthetist Action
Dissection towards the tracheaPrepare a syringe to deflate ETT cuff, mitigating perforation risk.
Transection of tracheal wallRemove tape on ETT, withdraw slightly to expose tracheal incision.
Tracheostomy tube insertionEnsure circuit is ready to connect to the tube, considering flexible connections for ease.

VERIFICATION POST-TRACHEOSTOMY

  • Confirm tube placement rapidly via end-tidal CO2 waveform analysis and auscultation for bilateral breath sounds.
  • Resume pre-op ventilatory settings, particularly for those requiring mechanical ventilation.
  • Avoid removing the ET tube until placement confirmation of the tracheostomy tube is ensured.

TRACHEOSTOMY POST-OP MANAGEMENT

  • Monitor for complications including pneumothorax, subcutaneous emphysema, and cardiac tamponade.
  • Facilitate safe transfer back to ICU or PACU with emergency supplies.
  • Adjust cuff pressures to avoid ischemic injury to trachea.
  • Exercise care during suctioning as the stoma may take five days to fully establish.

LARYNGECTOMY

  • Indications and types defined:

Supraglottic Laryngectomy

  • Surgical removal of the larynx up to the base of the tongue, preserving true vocal cords but necessitating temporary tracheostomy.

Partial Laryngectomy

  • Goals are preservation of laryngeal function (phonation and swallowing) through removal of select portions.

Total Laryngectomy

  • Involves complete removal of larynx and associated structures, which leads to voice loss and a trach tube dependency.

LARYNGECTOMY PRE-OP ASSESSMENT

  • Patient demographic considerations often include being elderly with histories of ETOH/tobacco use.
  • Evaluate respiratory function through ABGs, PFTs, CXR, noting any CO2 retention or hypoxemia.
  • Investigate any potential difficulties with eating, weight loss, malnutrition, or electrolyte imbalances.
  • Ensure thorough airway assessments due to edema or tumors.
  • Review prior imaging to assess for anatomy disruption or deviation.

LARYNGECTOMY ANESTHESIA

Anesthetic Techniques

  • Standard monitoring with additional arterial/central lines based on comorbidity risk.
  • General anesthesia through ETT is preferred for airway safety, with airway challenges anticipated.

Difficult Intubation Preparation

  • Ensure readiness for possible difficult intubation scenarios with a well-stocked airway cart.
  • Utilize fiberoptic techniques if airway evaluation is required preoperatively.

OR Table Considerations

  • Anticipate potential changes up to 180 degrees in operating theater positioning to facilitate surgical exposure and reduce blood loss.
  • Monitor patient for any signs of venous air embolism due to open neck veins.

LARYNGECTOMY POST-OP CONSIDERATIONS

  • Provision for effective postoperative analgesia.
  • Assess and ensure reversal of neuromuscular blockade.
  • Routine monitoring for exacerbating complications such as nerve injuries or pneumothorax.

RADICAL NECK DISSECTION (RND)

  • Procedure indicates lymphadenectomy addressing local tumor invasion; it typically results in various resections including sternocleidomastoid muscles and internal jugular vein.
  • Types of neck dissection:
    • Modified RND: Spares some anatomical structures while fully excising affected lymph nodes.

RND ANESTHESIA

  • Similar anesthetic considerations as laryngectomy.
  • Careful monitoring of fluid balance is crucial and avoidance of vasoconstrictors is paramount for flap viability.
  • Gather pre-anesthesia information on functional implications of cervical sympathetic outflow on cardiac rhythm.

POST-OP CONCERNS FOR RND

  • Anticipate complications such as hematoma or shoulder dysfunction.
  • Address any nerve injuries that may result from surgical intervention, preserving optimal function wherever possible.

FACIAL FRACTURES

  • Caused by blunt trauma; impact on airway patency and other vital functions.
  • Classification by LeFort system details the specifics of the fracture locations and implications.

LEFORT I FRACTURE

  • Maxillary fracture with moderate airway compromise; oral or nasal intubation is feasible.

LEFORT II FRACTURE

  • Pyramidal facial fracture posing a relative contraindication for nasal intubation due to fracture risk.

LEFORT III FRACTURE

  • Complete craniofacial separation, often necessitating awake tracheostomy for airway security.

FACIAL FRACTURES PRE-OP

  • Follow systematic trauma care protocols ensuring mental status checks for ETOH/drugs, and assess possible coexisting injuries that may complicate airway management.

FACIAL FRACTURES ANESTHESIA

  • In the absence of airway difficulties, IV induction is appropriate.
  • Maintaining hemodynamic stability and utilizing nasal RAE tubes should be judiciously approached.

EMERGENCE CONSIDERATIONS

  • Be aware of facial edema which may complicate early extubation; ensure criteria are strictly met pre-removal of ETT.

FACIAL FRACTURES POST-OP

  • Monitor intubated patients for inadvertent extubation risk; wire cutters must be accessible post-operation if jaws are wired.
  • Prophylactic measures for nausea and vomiting due to potential blood ingestion during surgery must be considered.

CONCLUSION

  • Successful management of anesthesia in head and neck procedures requires a comprehensive understanding of underlying conditions, surgical techniques, and potential complications.
  • The anesthetic approach must be tailored to each patient's unique needs and surgical considerations to ensure optimal outcomes and patient safety.