What the Anesthesiologist Should Know before the Operative Procedure

Head and neck cancer patients pose major anesthetic challenges due to local invasion around the larynx and pharynx, in most cases, and due to changes caused by radiation or previous surgery in the region.

A primary challenge for anesthesiologists with patients undergoing procedures around the head, neck, and face area is the fact that the operative field often involves the upper and/or lower airway, requiring the anesthesiologist to share the space with the surgeon.

Most of the patients coming for this type of surgery are elderly, with numerous comorbidities such as hypertension, coronary artery disease, diabetes, and bronchitis; furthermore, many may have difficult airways. One of the most important clues for recognizing a difficult airway would be the presence of obstructive symptoms such as dyspnea, stridor, orthopnea, dysphagia, exercise intolerance, and any recent change in voice. A current x-ray of the neck along with CT scans and/or MRI images of the head and neck area will give the anesthesiologist important information about the anatomy of the airway.

Also pertinent is a history of smoking, alcohol consumption, and drug use. Many of these patients may have undergone chemotherapy, radiation treatment, and prior surgical procedures, which may make the airway management challenging.

Chemotherapy is often used to enhance the response of cancer cells to radiation but in itself can cause toxicity to the lungs, heart, bone marrow, and gastrointestinal systems, causing pulmonary fibrosis, endocardial fibrosis, pancytopenia, and gastrointestinal toxicity such as oral ulceration, diarrhea, malnutrition from poor appetite, poor absorption leading to vitamin deficiency, and even electrolyte imbalances. Radiation causes fibrosis of the submandibular and sublingual structures and also affects the temporomandibular joints and cervical spine, increasing the difficulty for intubation.

The anesthesiologist should have a detailed discussion with the surgeon about the operative plan, whether muscle relaxants are permitted or not, and whether hypotensive anesthesia would be required. Often, the operative field for head and neck reconstructive procedures involves sites distant from the primary deformity.

Many patients may get autologous tissue transfer from the chest (e.g., rib harvest for temporomandibular joint reconstruction), upper or lower extremity (e.g., radial forearm or fibular vascularized free tissue grafts for extirpative reconstruction), or local rotational flaps (e.g., pectoralis major flap, scapular flap, forehead flap etc.). Microvascular surgery may be involved, and such operations are often lengthy procedures and require perfect relaxation and good hemodynamic conditions.

Other special surgical methods, such as robotic surgery and the intraoperative use of lasers, are increasingly becoming commonplace.

Also, a discussion about the airway, nasotracheal or orotracheal, or, in cases of a suspected difficult airway, advanced planning with adequate preparation for a fiberoptic intubation or intubation with special equipment, such as the GlideScope, video laryngoscope, jet ventilator, bougie, and retrograde intubation equipment, should be at hand.

Finally, a discussion about the postoperative plan should be clear on whether the patient will be extubated or remain intubated and ventilated electively in the ICU. In some cases, it is prudent to consider elective surgical airway preoperatively. Sometimes the endotracheal tube is replaced intraoperatively with a tracheostomy tube.

Finally, many of these procedures can be lengthy, with attendant stresses on the heart, lungs, and kidneys, and involving massive fluid shifts and blood loss. Therefore, the use of invasive monitoring and postoperative ventilation as a possibility should be discussed, and arrangements made accordingly.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

All head and neck cancer surgeries are urgent, and surgery should be performed as soon as the patient can be optimized. This often involves the input from a team of specialists, who can help prepare and work up the patient toward optimal physical condition so he or she can endure the surgical procedure.

On the other hand, it is also imperative to avoid unwarranted delay by conducting tests that do not have a significant effect on the surgery and anesthesia itself.

Emergent: Acute loss of airway in a patient due to aspiration, closure of tracheostomy with inspissated mucus plugs, and acute bleeding from friable cancerous growths will require immediate attention and relief.

Patients with large intraoral tumors may sometimes present with stridorous breathing, air hunger, cyanosis, and airway obstruction. Such cases may require percutaneous transtracheal jet ventilation or an urgent tracheostomy under local anesthesia to secure the airway. In such cases, there is probably scant time to prepare and the urgency of the situation requires quick thinking and skilled surgical management.

At first, ventilation with a face mask and airway should be attempted and the anesthesiologist may try to intubate after topicalizing the airway with local anesthetic, using a fiberoptic bronchoscope – failing which, a laryngeal mask airway or Combitube may be used. If it is a cannot-ventilate–cannot-intubate situation, then the next step in the difficult airway algorithm should be followed.

Clumsy repeated attempts can only worsen the prognosis for the patient. Ideally, the ENT surgeon is around to perform emergency tracheostomy; otherwise, the anesthesiologist should perform a cricothyrotomy puncture and ventilate, using jet ventilation or conventional ventilation until surgical tracheostomy can be performed.

In emergent cases, the extent of tumor progression may not be known, and in these cases, cricothyrotomy or even tracheostomy can be difficult to perform. Bleeding may occur if friable cancerous tissue is handled roughly and can further worsen airway obstruction.

Malnourishment and dehydration need correction prior to surgery.

Urgent: Once the patient is diagnosed with cancer, all head and neck tumors should be treated urgently. The concerns are the condition of the airway, the general physical status of the patient, and concomitant cardiac and pulmonary disease, such as hypertension, coronary artery disease, and chronic obstructive pulmonary disease.

Elective: There are few primary head and neck cancer cases that can be called elective. Most patients, however, undergo repeated cosmetic procedures after the primary cancer is excised and these patients can have a worsened airway due to anatomical changes caused by prior surgery. These procedures can be lengthy, such as reconstructive rotational flap operations requiring microvascular techniques and tissue transfer from distant sites in the body.

All the concerns described previously exist in these patients, and careful perioperative management requires the interaction between numerous specialists of different disciplines. Head and neck cancer can metastasize to the liver, lung, and bone, and surgery may be required to excise isolated lesions.

2. Preoperative evaluation

The most important concern in all head and neck cancer patients is the condition of the airway. A history of dyspnea, dysphagia, obstructive sleep apnea, a change in the voice, exercise intolerance, radiation to the head and neck region, previous head and neck surgery, and previous difficulty with intubation may be clues to a difficult airway.

Some patients with pharyngeal, neck, or anterior mediastinal tumors may have airway obstruction when lying supine but can breathe when lying prone or in a lateral position. Apart from a thorough physical examination of the airway from the teeth inwards, preoperative evaluation of the airway may include direct and indirect laryngoscopy, bronchoscopy, and radiological tests, such as antero-posterior and lateral X-rays films of the neck, CT scans, and MRI images to determine the state of the airway anatomy and the extent of cancer spread.

The condition of the recurrent laryngeal nerve should be known preoperatively for medical and medico-legal reasons because paresis and paralysis of the recurrent laryngeal nerve may not be manifested by voice changes preoperatively but may be unmasked by voice change postoperatively.

Radiation therapy to the head and neck often limits mouth opening, neck mobility, and causes fibrosis in the submandibular and sublingual region, leading to rigidity in the soft tissue, which can be unyielding during laryngoscopy or external digital manipulation. This can cause the larynx to be anterior despite a normal mento-hyoid distance.

Midline friable tumors pose a greater challenge to intubation than tumors to the side. Tumors of the base of the tongue, epiglottis, and vallecula are usually unyielding to the laryngoscope and may cause difficulty in visualizing the vocal cords. Disturbance in the oro- and hypoparyngeal muscles causes difficulty with deglutition and increases the risk of aspiration in these patients.

Most of the patients with head and neck cancer are elderly and may suffer from chronic obstructive pulmonary disease, bronchitis, hypertension, coronary artery disease, hypercalcemia, diabetes mellitus, and obesity. They also may have a long history of tobacco smoking, alcoholism, and severe malnutrition and dehydration due to improper food intake. Some of these patients can also present with significant immunosuppression and cachexia. Several of these patients may also have undergone chemotherapy to enhance the response of cancer cells to radiation therapy. This allows less invasive head and neck surgery with larynx sparing.

Chemotherapy drugs such as cisplatin, fluorouracil, methotrexate, carboplatin, paclitaxel, and docetaxel are used. They can cause myelosuppression, leading to thrombocytopenia and neutropenia. Paclitaxel and carboplatin can cause cardiac toxicity, such as arrhythmias, atrioventricular blockade, interstitial pneumonitis, and lymphocytopenia. Methotrexate may cause gastrointestinal toxicity, such as ulcerative stomatitis, diarrhea, electrolyte imbalance, and weight loss. It is also known to cause hepatic and renal dysfunction. Almost all chemotherapeutic agents cause nausea and vomiting and loss of appetite.

Head and neck cancers spread locally and by metastasizing to other organs, such as the lung, liver, brain, and bone, and can cause changes in those organs, leading to decreased lung and liver function, pathological fractures, coagulopathy, and cerebral edema.

Medically unstable conditions warranting further evaluation include patients with active myocardial ischemia or myocardial infarction, unstable arrhythmias, TIA (transient ischemic attack), stroke, and active COPD exacerbation, which may need further assessment and treatment prior to surgery.

Delaying surgery may be indicated if the condition can be treated and improved in a short time. Otherwise, delay in surgery is unjustified in patients with cancer.

3. What are the implications of co-existing disease on perioperative care?

Perioperative evaluation: Head and neck cancer is a broad term that includes cancer occurring in several areas of the head and neck. The cancer can occur in the nasal cavity, sinuses, oral cavity, oropharynx, larynx, salivary glands, thyroid, and parathyroid glands. Skin cancers of the scalp, face, and neck are also considered head and neck cancers.

Patients coming for head and neck surgery in the United States are typically male (63%) and over the age of 60 years. Most of them have a long history of tobacco and alcohol abuse, poor oral hygiene, dietary deficiencies, and infections. They may also suffer from COPD, coronary artery disease, hypertension, obesity, and diabetes, which is common in this age group.

Perioperative risk reduction strategies: The patient should continue taking his or her usual medications for seizures, COPD, hypertension, angina, or arrhythmias prior to his surgery.

If the patient is an insulin-dependent diabetic, his or her blood sugars should be managed using frequent blood sugar estimations and, possibly, a sliding scale of constant insulin infusion. The patient should, however, stop his oral antidiabetic medications on the day of surgery; he or she may require insulin during the postoperative period until oral medications can be resumed.

Nowadays anesthesiologists also allow anti-Parkinson drugs, antidepressants, and statins to be taken prior to surgery. All other medications, including herbal supplements, are usually stopped prior to surgery.

If the patient has active coronary disease that requires stent placement ,it will take precedence to this operation. Malignant arrhythmias also need to be treated prior to surgery, possibly by placement of a pacemaker or a cardioverter defibrillator. In some cases of severe coronary artery stenosis, a cardiac bypass procedure may have to be performed prior to cancer surgery. The opinion of the cardiologist is invaluable in guiding therapy in these difficult situations.

b. Cardiovascular system

Acute/unstable conditions: As these patients are elderly, many of them may have concomitant cardiovascular disease, such as coronary artery disease, arrhythmias, heart blocks, and myocardial infarction. They may also have had cerebrovascular accidents or may actively be having TIA attacks. The carotids may be directly involved through head and neck cancer spread, and this may result in stenosis and cerebral ischemia.

All patients scheduled for major head and neck surgery require a thorough cardiac evaluation, which may include such tests such as 12-lead ECG, Holter monitoring, cardiac biomarkers (troponin assay), echocardiogram for wall motion abnormality detection, as well as the opinion of a cardiologist. Events such as acute ongoing coronary ischemia may need to be treated prior to head and neck surgery. Malignant arrhythmias may need the placement of a pacemaker or an implantable cardiac defibrillator.

Chemotherapeutic drugs, such as paclitaxel used in the treatment of head and neck cancers, can cause both brady- and tachyarrhythmias, ventricular tachycardia, ventricular fibrillation, and asystole. Radiation injury to the heart can result in constrictive pericarditis and pericardial effusions, which may require drainage. It may also cause myocardial fibrosis and restrictive cardiomyopathy. Rarely fibrosis occurs around the coronary arteries, causing angina and myocardial infarction in the absence of atherosclerotic heart disease. Rare malignancies such as the glomus tumors can cause hypertensive crisis by releasing catecholamines, and these tumors behave like pheochromocytomas.

Baseline coronary artery disease or cardiac dysfunction – goals of management: The patient’s functional status, changes in exercise tolerance, and any recent onset of fatigue needs to elicited. Previous cardiac examination results, if available, will help us determine if the disease is stable or progressive. A discussion with the patient’s cardiologist or primary care physician will also reveal useful information regarding the patient’s cardiac status. Outcome studies do not show any increased benefit from enhanced preoperative cardiac testing when performed in intermediate risk patients or in patients who do not have any signs and symptoms of acute ischemia.

c. Pulmonary

COPD: Patients with head and neck cancer frequently suffer from pulmonary diseases. Most of them have a long history of tobacco abuse, and, as the disease progresses, are increasingly prone to aspiration as the muscles of deglutition do not function properly.

Chemoirradiated patients lack sufficient laryngeal sensation to detect aspiration, and the incidence of subclinical or silent aspiration is more than that of clinical aspiration. These patients are increasingly at risk for developing postoperative pulmonary complications, such as pneumonias and interstitial lung disease.

Dyspnea from upper airway obstruction must be distinguished from COPD. Flow-volume (FV) loops show a decrement in the inspiratory portion of the FV loop when the obstruction is extrathoracic and a decrease in the expiratory portion of the FV loop when the lesion is intrathoracic. There are several head and neck tumors that are supraglottic and cause inspiratory stridor and airway obstruction.

Chemotherapeutic agents such as methotrexate can cause a reduction in the diffusion capacity of the lung, and drugs such as paclitaxel and docetaxel can cause hypersensitivity reactions, leading to dyspnea and bronchospasm.

It is important to get the patient to stop smoking and treat any intercurrent infections with antibiotics prior to surgery. ARDS (acute respiratory distress syndrome) is one of the most severe complications and may develop in patients with chronic lung disease after major head and neck cancer surgery. The origins of ARDS may be sepsis, bronchial aspiration of gastric contents, or massive blood transfusions, or it may have several concurrent etiologies. This condition would require ventilation and intensive care management for several days. Postoperative ARDS in cancer patients may be the result of direct toxins, free radicals, and cytokines working on the alveolar capillary membrane, causing an altered permeability. Low ventilation volumes and pressures with permissive hypercapnia may help in the treatment of ARDS.

Reactive airway disease (asthma): Patients with asthma should be encouraged to stop smoking and should continue with their current pulmonary medications and nebulizers. Any history of recent steroid use must be noted and a stress dose of steroids should be given prior to surgery.

Airway manipulation and extubation may trigger bronchospasm and in patients with status asthmaticus, the breathing tube may have to be removed under deep anesthesia or with a ketamine cover. In the post–head and neck surgical patient, the management a reactive airway can be quite problematic.

d. Renal-GI:

Renal: These patients may often be dehydrated and suffering from electrolyte imbalances because of their inability to swallow liquids. The tumors may also release hormones, resulting in hypercalcemia.

These patients may need to be hydrated with intravenous fluids before the operation. Drugs such as methotrexate may cause renal tubular necrosis, decreasing renal function.

Preoperative laboratory work-up for baseline serum electrolytes, BUN, and creatinine should be performed.

GI: These patients are usually malnourished because of difficulty with swallowing. They may be cachectic as a result, and their poor nutritional status may need to be corrected before surgery.

Chemotherapeutic agents such as methotrexate can affect the GI tract, causing nausea, vomiting, anorexia, ulcerative stomatitis, and diarrhea. The risk of having a full stomach before induction of anesthesia, leading to aspiration, must also be kept in mind.

Head and neck cancers can metastasize to the liver, altering liver function tests and affecting coagulation and causing hypoalbuminemia. Many patients also have a history of alcoholism, which could also affect the liver function adversely.

e. Neurologic:

Acute issues: Patients suffering from TIAs and strokes may require treatment prior to major head and neck surgery. Careful history of loss of consciousness, cerebrovascular disease, and carotid stenosis should be noted. Preoperative testing with CT or MRI and carotid Doppler studies may be indicated. A neurological consultation may be required in certain cases. Intracranial metastasis can result in raised intracranial tension and cerebral edema.

Chronic disease: History of Parkinsonism, seizure disorder, and preexisting neurologic deficits should be recorded. Of particular importance in head and neck surgery is the examination of the recurrent laryngeal nerve. Routine preoperative indirect laryngoscopy to evaluate the vocal cord function of all patients presenting with thyroid cancer is important for medical and medicolegal reasons.

Medically, it is important to detect nerve palsy, which may not be accompanied by voice changes because of compensation by the nerve on the other side. This would make it imperative to try and save the only functioning nerve. Medicolegally, such evaluation demonstrates the presence or absence of nerve function preoperatively, a fact of great importance in case of any postsurgical voice change.

f. Endocrine:

Head and neck tumors releasing endocrine secretions are the following:

Medullary thyroid tumors release thyrocalcitonin, causing hypocalcemia, hypotension, congestive heart failure, inspiratory stridor, and muscle weakness.
Malignant parathyroid tumors release parathormone, causing hyperparathyroidism, hypercalcemia, hypertension, heart block, renal dysfunction, polyuria, seizures, hypophosphatemia, hemolysis, platelet dysfunction, and decreased ventricular contractility.
Glomus tumors can release catecholamines, 5-hydroxytryptophan, kallikrein, and serotonin. The tumor mimics a pheochromocytoma or carcinoid in its actions and can result in a hypertensive crisis.
Patients develop syndrome of inappropriate antidiuretic hormone secretion (SIADH) during head and neck cancer surgical procedures. Limiting intravenous fluids can prevent fluid overloading and cardiac sequelae.

g. Additional systems/conditions that may be of concern in a patient undergoing this procedure and that are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

The airway is of primary concern in all head and neck surgeries. These patients may also have received chemotherapy, resulting in myelosuppression, neutropenia, and lymphocytopenia. They may also suffer from chronic anemia due to inadequate nutrition and multiple vitamin deficiencies.

Most of these cancer patients also suffer from depression and anxiety and may be on several antidepressant medications. They could also be receiving heavy doses of opioids for pain control and may be experiencing various forms of cognitive dysfunction, ranging from sedation to delirium to unconsciousness.

4. What are the patient's medications and how should they be managed in the perioperative period?

In common with other elderly patients, patients could be on a variety of cardiac medications:

Beta blockers, calcium channel blockers, and ACE inhibitors for rate and blood pressure control should be continued in the perioperative period.
Statins should be continued perioperatively to prevent adverse cardiac events.
Aspirin, which is usually stopped 4 days prior to surgery, is restarted postoperatively once the patient can take oral medication.
Patients with recent coronary stents may be on drugs such as clopidogrel, which should be stopped after a discussion with the cardiologist and the surgeon.
Patients may be on opiates for pain management, which are converted to parenteral form in the perioperative period. Opiates can be taken preoperatively too.
Antidepressants may be allowed on the day of surgery, and any monoamine oxidase inhibitor use should be noted; Demerol may not be used in these patients.
Patients should continue using their acid reflux medications in the preoperative period.
Patients using inhalers should continue using them preoperatively.
All herbal medications, vitamin E, and over-the-counter medicines should be stopped a week before surgery.
NSAID medications should also be stopped at least 4 days before surgery.
If the patient is on Coumadin: The medication should be stopped at least 4 days before surgery and a substitute injectable anticoagulant should be used instead.
Patients on antiplatelet medications for stroke or cerebrovascular disease should be managed by the neurologist and surgeon.
All anti-Parkinson drugs and antiseizure medications should be given preoperatively.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Patients may have received chemotherapy with radiation prior to surgery. Some of the commonly used chemotherapeutic agents are methotrexate, paclitaxel, docetaxel, cisplatin, 5-fluorouracil, and cetuximab.

All chemotherapeutic agents can cause myelosuppression, coagulopathies, thrombocytopenia, anemia with ulceration, and bleeding from the gastrointestinal tract. The side effects of methotrexate also include pulmonary infiltrates, renal tubular necrosis, and hepatic dysfunction. Drugs such as paclitaxel and docetaxel can cause arrhythmias, atrioventricular block, fluid retention, deep vein thrombosis, and congestive heart failure. 5-fuorouracil causes bone marrow depression, megaloblastic anemia, acute cerebellar syndrome, gastrointestinal and hepatic toxicity; cisplatin can cause renal damage, neuropathies, areflexia, ocular toxicity, loss of hearing, bronchospasm, and cardiac arrhythmias.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac: See discussion above. Continue beta blockers, calcium channel blockers, and ACE inhibitors as usual. Some anesthesiologists recommend that ACE inhibitors should not be taken preoperatively for fear of refractory hypotension when used with a total intravenous anesthetic technique.

Pulmonary: Continue all inhaler therapy and bronchodilator medications preoperatively.

Renal: Diuretics should be stopped, but antirejection drugs may be continued preoperatively.

Neurologic: Continue all antiseizure and anti-Parkinsonism drugs preoperatively.

Antiplatelet:
Antiplatelet drugs should be taken or omitted after consulting the primary care physician or neurologist who prescribed the drugs.

Psychiatric: All psychiatric medication can be taken preoperatively and note should be made of any monoamine oxidase inhibitors so that demerol can be avoided in these patients.

j. How To modify care for patients with known allergies

Avoid the drug that causes allergy and use a substitute drug.

k. Latex allergy: If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

A list of drugs containing latex bottle tops should be available in every pharmacy, and these drugs, if used, should have their tops pried open using a bottle opener.

All personnel should use nonlatex gloves, tourniquets, catheters, and all anesthesia equipment must be latex free.

All drugs needed for the treatment of an anaphylactic reaction should be at hand before the start of the case. No special pretreatment is required if the above steps are followed.

l. Does the patient have any antibiotic allergies- [Tier 2- Common antibiotic allergies and alternative antibiotics]

If the patient has antibiotic allergy, then a nonallergenic antibiotic should be used.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia (MH)

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents:

Proposed general anesthetic plan: Prepare the anesthetic machine to rid it of trace anesthetic gases; change the soda lime canister and circuitry; and remove all vaporizers for added safety.

Ensure MH cart available: Check that sufficient a amount of dantrolene is available.
Family history or risk factors for MH: If a close relative has had a positive contracture test, then it is not unreasonable to treat the patient as an MH-susceptible patient. The fact that the patient may have had previous uneventful anesthetics is no guarantee that MH is ruled out completely.
Local anesthetics/muscle relaxants: Some people claim to be allergic to local anesthetic agents and if absolutely needed, an alternate local anesthetic may be tried. The same applies to muscle relaxants, as all our presently used nondepolarizing agents are remarkably safe.

5. What laboratory tests should be obtained and has everything been reviewed?

Common laboratory normal values will be same for all procedures, with differences by age and gender.

Hemoglobin levels: Hematocrits in the range of 38% to 46% is desirable.

Electrolytes: The serum electrolytes should be in the normal range, and any hypo- or hypercalcemia and hyperkalemia should be corrected preoperatively.

Coagulation panel: Normal coagulation times (PT, APTT, INR) should be present.

Imaging: A cardiac stress test, echocardiogram report, chest X-rays, and lateral and anteroposterior x-rays of the neck to visualize tracheal narrowing and deviation are helpful. CT scans, MRI, and PET scan images – all can give useful information about the extent and size of the tumor and the structures it is involving.

Other tests: ECG, pulmonary function tests, liver function tests, and direct and indirect laryngoscopy to assess vocal cord movement and recurrent laryngeal nerve function could help with the conduct of anesthesia and surgery. Laryngoscopy can tell clinicians if the tumor is solid or friable and if the tissues are fixed or movable. All of the above information can help the anesthesiologist during airway management.

Intraoperative Management: What are the options for anesthetic management, and how should the anesthesiologist determine the best technique?

Head and neck cancer surgical cases are usually lengthy procedures performed on elderly patients, often involving considerable blood loss and are performed under general anesthesia. Some panendoscopies may be performed using sedation and analgesia. Regional blocks and topical anesthesia is used to facilitate awake fiberoptic intubation prior to induction of general anesthesia.

Few areas of anesthesia pose a greater challenge to airway management than head and neck cancer patients. Securing the airway in the perioperative period is the key goal for the anesthesiologist. Some surgeons request that muscle relaxants not be used so that nerve monitoring may be performed during surgery. In microvascular surgical cases, the surgeon may request that pressors not be used during the case because the surgeon may be concerned about the vascularity and perfusion to the flap. On the other hand, hypotensive anesthesia may be requested to minimize blood loss in cases of skeletal disimpaction.

In recent years, robotic and laser surgical techniques have gained popularity; and these methods involve special training to cope with problems that may arise under these conditions. During surgery, the patient is typically supine, with the head tilted up to 30 degrees to allow visualization of the neck. In this position, vascular damage to major vessels, such as the internal jugular vein, may result in air entrainment and embolization.

Regional anesthesia

Regional anesthetic techniques are primarily used to block airway reflexes during awake intubation. In cases of compromised airway, it may not be wise to sedate the patient. In other cases, small doses of intravenous remifentanil and propofol along with supplemental oxygenation may be used to facilitate the performance of the blocks.

Peripheral nerve block

Preparation of the patients for awake fiberoptic intubation includes premedication (which should be avoided in patients with airway obstruction), antisialogogue administration, topicalization, and nerve blocks from the nasal cavity down to the trachea. The nerves to be blocked include the sphenopalatine, glossopharyngeal, and internal branch of the superior laryngeal nerve.

Topicalization of the oral mucosa is done with lidocaine or benzocaine spray. The glossopharyngeal nerve supplies the sensory innervation to the posterior third of the tongue, the oropharynx, and the tonsillar area and controls the gag reflex. It can be blocked by infiltrating 3 mL of 2% lidocaine posterior to the palatopharyngeal fold at its midpoint, 1 cm deep to mucosa of the lateral pharyngeal wall.

The internal branch of the superior laryngeal nerve innervates all the mucosa above the rima glottidis, including the epiglottis and the aryepiglottic fold. The block should be used with caution in full stomach cases as it removes some protective laryngeal reflexes. It is blocked by applying local anesthetic for 3 to 5 minutes to the pyriform fossa mucosa or, in the absence of a neck tumor, a 23-gauge needle is placed 1 cm medial to the superior cornu of the hyoid bone and directed caudad to pierce the thyrohyoid membrane. After aspiration, 2 mL of 2% lidocaine can be injected.

The recurrent laryngeal nerves can be anesthetized by a cricothyroid membrane puncture with a 22-gauge needle and by quickly injecting 4cc of 4% lidocaine intratracheally. This will make the patient cough, and spreads the anesthetic in the trachea and blocks the recurrent laryngeal nerve. This block should not be performed if the tumor tissue has distorted normal tracheal anatomy.

The maxillary nerves can be blocked if a nasotracheal intubation is planned and the mandibular nerve block can eliminate masseter muscle tone and relax the jaw.

Benefits: These blocks help with awake fiberoptic intubation in a head and neck cancer patient.

Drawbacks: The blocks may be difficult to perform due to distortion of the normal anatomy owing to tumor growth, radiation, or prior surgery.

Issues: There is no need to hold anticoagulants for the performance of these blocks.

General anesthesia

Benefits: Head and neck cancer surgery can vary from a short endoscopy, biopsy, or laryngoscopy to a lengthy radical neck dissections, laryngectomy, and reconstructive surgery with rotational flaps.

Most major head and neck cancer surgery is done under general anesthesia because they tend to be long in duration and require a still and relaxed patient. Under general anesthesia, the airway is secure. Intraoperatively, the surgeon may want to monitor nerve function and he may request that no muscle relaxants be used. General anesthesia is essential when lasers are used. Major reconstructive procedures such as autologous grafts for rotational or microvascular free flaps could involve sites distant from the operative site and, therefore, general anesthesia is required to enable this surgery. Recently, more robotic surgery is being done, which requires absolute muscle relaxation and, therefore, needs to be done under general anesthesia.

Drawbacks: (1) May increase the incidence of postoperative confusion and delirium in the elderly. (2) Need to secure the airway under challenging circumstances.

Other issues: (1) In certain surgical procedures where nerve monitoring is required, muscle relaxants should not be used. (2) Whenever lasers are used around the airway, special laser-proof endotracheal tubes should be used. The surgeon may request 30% oxygen in nitrogen or helium instead of nitrous oxide to reduce the risk of airway fires. (3) Often, the operating room table is turned away from the anesthesiologist in order to accommodate the surgical team and large instruments, and the anesthesiologist has no access to the airway area during the entire operation.

Airway concerns: Airway is the major concern in head and neck cancer surgery. Careful preoperative assessment is essential. Detailed preparation of the patient for awake intubation includes using nerve blocks. All ancillary emergency airways and intubating devices should be at hand. The surgeon should be present during induction and should be ready to perform a surgical airway if needed.

Sometimes, when numerous operations are contemplated, it may be prudent to perform a tracheostomy before the start of the main surgical procedure. Often, the surgeon exchanges the endotracheal tube with a tracheostomy tube during surgery. Extubation should be done once the patient is fully awake and after ensuring that no airway edema exists. It is again important to have the surgeon in the room in case of airway obstruction requiring reintubation.

Monitored anesthesia care

Benefits: The use of monitored anesthesia care (MAC) in head and neck cancer surgery is limited. MAC is used for excision of superficial cancerous skin lesions in the head and neck area, for panendoscopies, and biopsies. MAC ensures that the patient can be woken up quickly once the procedure is over and does not require an endotracheal tube.

Drawbacks: (1) Patients with severely compromised airways should not be sedated at any given time. (2) The airway is not protected and aspiration may occur. (3) Intubation or a surgical airway may be needed urgently if the airway closes.

Other issues: The patient may not cooperate or tolerate MAC and general anesthesia may be needed.

6. What is the author's preferred method of anesthesia technique and why?

The author prefers general anesthesia because of the complexity and length of the procedure. After securing two large bore intravenous cannulas, an arterial line (not on same arm if a radial flap is planned), and a central venous pressure line,prepare the patient for intubation. The choices are an awake fiberoptic intubation or, if the airway is favorable, plan on inducing general anesthesia and intubating with an armored, nonkinkable endotracheal tube with full relaxation.

Make sure that a difficult airway cart with all emergency airway devices is in the operating room. All monitors (ECG, NIBP, arterial blood pressure, central venous pressure, peripheral nerve stimulators, precordial Doppler) will be applied and anesthesia will be induced after careful preoxygenation in the presence of a surgeon, who will be standing by to perform a surgical airway if necessary.

Once the airway is secured, the patient is positioned for surgery and all pressure points should be padded; and anesthesia is maintained with oxygen, air, and an inhalation agent. A rectal temperature probe is placed for temperature monitoring, as the mouth and nose are not accessible. Warming devices, such as the Bair Hugger® and fluid warming devices, are used during the case to prevent hypothermia.

Long-acting opiates should be given to provide analgesia during the operation. If muscle relaxants are allowed, run it as an infusion. Try to maintain hemodynamic control, avoiding bradycardia or tachycardia, and keep the mean arterial pressure between 65 and 75 mm Hg to achieve mild hypotension and to prevent excessive blood loss. Be mindful of the patient’s preexisting cardiac and pulmonary disease while administering fluid therapy, blood transfusions, or drugs.

At the end of surgery, the throat pack should be removed, the throat and stomach should be suctioned, and the airway examined for any edema that would require the endotracheal to be left in place for elective postoperative ventilation. If no edema is evident, extubation, in the presence of a surgeon, should be attempted.

The muscle relaxant is reversed, and once the patient is fully awake and is able to breathe spontaneously, follow commands, and pass a leak test (audible leak around the deflated endotracheal tube cuff during positive pressure ventilation), the endotracheal tube is removed over a jet stylet catheter or a Cook Airway. This will permit the anesthesiologist to monitor the breathing and allows for suctioning, jet ventilation, or, if the need arises, even reintubation. Once the patient stabilizes, this catheter can be removed. The difficult airway cart should be at hand during extubation and at hand afterwards in the recovery room.

What prophylactic antibiotics should be administered?

Based on current recommendations published in October 2009, antibiotic prophylaxis for head and neck cancer surgery consists of (1) cefazolin 2 g IV within 1 hour of surgery; (2) clindamycin 600 mg IV within 1 hour of surgery if the patient is allergic to beta-lactam antibiotics; (3) ampicillin/sulbactam 1.5 g IV within 1 hour of surgery; (4) cefazolin 1 g with metronidazole 900 mg IV 1 hour prior to surgery.

What do I need to know about the surgical technique to optimize my anesthetic care?

A discussion with the surgeon about the airway is very important. (1) Is a surgical airway planned and will it be done prior to the main surgery or during the surgery? (2) The route of intubation: naso- or orotracheal? (3) in microlaryngoscopic operations, jet ventilation through a laryngoscope or ventilation through a smaller diameter, longer endotracheal tube (31 cm) is used. (4) Will the surgeon be doing nerve monitoring or are muscle relaxants permitted? (5) If lasers are used, laser-proof endotracheal tubes are needed and nitrous oxide is not permitted. (6) Pressors may not be used in microvascular procedures for fear of causing vasoconstriction in the graft. (7) If robotic surgery is planned, the patient needs to be fully relaxed and the anesthesiologist may not have access to the airway once surgery starts. (8) If a tracheostomy is done during the operation, the anesthesiologist should be ready to withdraw the endotracheal tube once the tracheostomy tube is in place or be prepared to advance it back into the trachea if needed.

Head and neck cancer: Head and neck cancer refers to cancers of the oral cavity, nasopharynx, oropharynx, hypopharynx, larynx, trachea, and the thyroid gland. The operations can range from excision of small, isolated growths to classic radical neck dissection with removal of sternocleidomastoid muscle, internal jugular vein, the spinal accessory nerve, submandibular gland, and block dissection of the regional lymph nodes.

The reconstructive operations may involve rotation flaps or microvascular free flaps from distant sites, such as the groin, rectus abdominis, parascapular region, and the forearm. Prior chemo- and radiotherapy make the dissection more difficult due to fibrosis and distortion of the normal anatomy, which, more dangerously, can lead to intraoperative carotid artery rupture. These cases can usually take a long time and may involve considerable fluid shifts, blood loss, and hypothermia. Since the majority of these patients are elderly in poor general health, it is difficult to balance risks from benefits. Major operations in this area can result in inadvertent injury to vital adjacent structures and manipulation of some tissues (carotid body and sinus) can cause wild hemodynamic swings.

As technology advances, so has the complexity of these procedures. The use of microvascular surgical techniques, lasers, and robotics is commonplace nowadays and the anesthesiologist has to tailor his anesthetic to suit the surgical plan. Patients undergoing robotic surgery have had fewer complications and shorter stays for oropharyngeal cancer surgery compared to conventional surgery, and its use is likely to increase in the future.

What can I do intraoperatively to assist the surgeon and optimize patient care?

The anesthesiologist has to keep the patient hemodynamically stable and relaxed without the help of muscle relaxants when nerve monitoring is being used during surgery. He/she may have to give anesthesia without nitrous oxide and use low oxygen saturations (30%) if lasers are being used and he may be asked not to use pressors and keep the blood pressures at baseline limits during microvascular surgical cases. Controlled hypotension may be requested during skeletal disimpaction surgery to prevent blood loss. It is also important to keep the patient warm and keep up with blood losses in a timely manner to maintain homeostasis. It must be noted that prolonged anesthesia times of 8 hours or more combined with large fluid shifts are associated with worse outcomes and both the surgeon and anesthesiologist must be cognizant of this fact.

What are the most common intraoperative complications and how can they be avoided/treated?

(1) Air embolism can result when air entrains through an open major vessel, such as the internal jugular vein. Air emboli are detected by the precordial Doppler or by a dip in the end tidal carbon dioxide tracing; therefore, the surgeon should be prepared to flood the field with saline, apply jugular vein compression, and prevent further entrainment of air.

The patient is turned to left lateral position with a slight Trendelenburg tilt. The nitrous oxide should be turned off and the patient should be ventilated with 100% oxygen. If a central venous line or a Bunegin Catheter is present, an attempt to remove air from the heart can be made. Hemodynamic support with pressors may be needed to ensure adequate preload. (2) Carotid body stimulation can occur when dissecting around the carotid bifurcation. This may result in extreme bradycardia, arrhythmia secondary to a prolongation of the QT interval – leading to cardiac arrest. The reflex may be blocked by injecting local anesthetic drugs around the carotid sheath near the carotid sinus. If the reflex occurs, it may be treated by stopping manipulation of the carotid sinus and giving a small dose of glycopyrrolate or atropine. (3) Pneumothorax from rib harvesting is a rare complication; a chest tube should be placed, and nitrous oxide switched off. (4) Resection of tumors in the vicinity of the base of the skull can lead to cerebrospinal fluid leak due to a dural tear, which may require repair. (5) Carotid artery rupture is a dreaded complication, either due to erosion of the artery due to tumor invasion or due to prior radiation therapy.

(6) Fires in the airway with lasers are well known. The incidence has decreased with the use of laser-proof endotracheal tubes. The cuffs of these tubes should be filled with colored saline to help detect a leak if it occurs. The lowest possible concentration of oxygen should be used (30%), nitrous oxide is avoided, and air or helium used instead. If the endotracheal tube catches fire, it should be removed immediately and the patient ventilated by mask using 100% oxygen. Bronchoscopy and esophagoscopy should be performed to assess damage and to remove any debris. The patient may be reintubated or tracheostomy may be needed. Prolonged ventilation, bronchial lavage, and intravenous steroids may be needed to reduce inflammation.

Complications

Cardiac: Air emboli, carotid body stimulation, carotid artery rupture may occur in patients who had radiation, tumor erosion into the carotid artery.

Pulmonary: Airway closure from hematoma, aspiration of gastric contents or blood, airway fire, pneumothorax, pneumomediastinum, subcutaneous emphysema due to jet ventilation mishaps, postoperative ARDS.

Neurologic: During the course of head and neck cancer surgery, there is a risk of nerve injury, especially in complex radical neck dissections. The recurrent laryngeal nerve, vagus, hypoglossal, phrenic, facial nerves, and spinal accessory nerve (cranial nerve XI) could be injured, leading to difficulty with phonation, swallowing immobility of the tongue, diaphragm paralysis, and painful shoulder. Resection of tumors near the base of the skull also can lead to cerebrospinal fluid leak due to a dural tear.

a. Neurologic:

Unique to procedure: In classic radical neck dissection, the spinal accessory nerve is sacrificed and this results in impaired shoulder movement and denervation of the trapezius muscle, leading to a painful, frozen shoulder.

b. If the patient is intubated, are there any special criteria for extubation?

A clear plan for extubation should be made with the surgeon prior to completion of surgery. Extubation is usually performed in the presence of the surgeon, so as to have expert help at hand should the need arise.

Extubation is contingent on several factors such as the length of the operation, the state of the airway prior to surgery, the extent of surgical dissection, suspected or expected airway complications as a result of the surgery, overall respiratory function, hemodynamic stability, level of consciousness, and return of airway reflexes.

Prior to extubation, a leak around the deflated endotracheal tube (ETT), upon positive pressure ventilation, should be evident. Direct visualization with a fiberoptic bronchoscope may reveal edema around the upper airway, which precludes any early extubation. If the airway looks suspicious on direct examination, it may be prudent to keep the patient intubated a while longer.

The patient’s head should be kept elevated to reduce tissue edema, and extubation is performed over a jet stylet or a hollow intubating catheter such as the Cook Airway. With this catheter in place, it is possible to ventilate the patient if necessary and suction the secretions from the tracheobronchial tree. If intubation is needed, an ETT can be advanced over this catheter. The airway can also be compromised by hematoma, aspiration, or by an inability to clear secretions.

The difficult airway cart should be positioned near the patient at all times in the immediate postoperative period.

c. Postoperative management

What analgesic modalities can I implement?

Pain management must be weighed against the risk of airway safety in these patients. Postoperative nausea and vomiting could be a serious problem, which could even mar the result of surgery. Patient-controlled analgesia along with aggressive antiemetic therapy seems beneficial. Nonsteroidal analgesics, if permitted by the surgeon, may be tried too.

What bed acuity level is appropriate?

An ICU bed may be needed if the patient is to remain intubated. Even if extubated, these patients should be in a monitored step-down unit, where the nursing care is more concentrated.

What are common postoperative complications, and ways to prevent and treat them?

Airway closure: May need reintubation.

Airway edema: Treated with humidified oxygen, racemic epinephrine and elevation of the head.

Hematoma: Needs evacuation.

Postoperative nausea and vomiting: Aggressive antiemetic treatment, avoidance of intraoperative nitrous oxide and judicious opiate use.

Hypocalcemia: Replenish calcium.

Blocked tracheostomy tube with inspissated mucus, blood, or tissue: Clean or replace the tracheostomy tube.

Postoperative delirium: Avoid benzodiazepines preoperatively; try physostigmine; may need sedation and reintubation.

Recurrent laryngeal nerve palsy: May need reintubation or tracheostomy, followed by vocal cord surgery at a later date.

What's the Evidence?

Jensen, NF, Benumof, JL. “The difficult airway in head and neck tumor surgery”. Anesth Clin North Am . vol. 11. 1993. pp. 475-511. (Discusses various types of head and neck surgery and special complications and management of airway emergencies.)

Garg, R, Darlong, V, Pandey, R, Punj, J. “Anesthesia for oncological ENT surgeries: review”. Internet J Anesth. vol. 20. 2009. (Preoperative evaluation of a patient with head and neck cancer and management of the postsurgical patient.)

Krohner, RG. “Anesthetic considerations and techniques for oral and maxillofacial surgery”. Int Anesth Clin. 2003. (Preparation of the patient for surgery, complications during surgery, and management of the postsurgical period.)

Feldman, MA, Patel, A, Miller, RD. “Anesthesia for ear, nose and throat surgery”. Miller's Anesthesia. 2010. pp. 2357-88. (An overview of head and neck cancer surgery with strategies for perioperative management of these patients.)

Fischer, SP. “Preoperative evaluation of the cancer patient”. Anesth Clin North Am . vol. 16. 1998. pp. 533-46. (Chemotherapy drugs commonly used to treat cancer and the side effects seen in the preoperative cancer patient.)

Sarma, VJ. “Use of ketamine in acute severe asthma”. Acta Anesthesiol Scan . vol. 36. 1992. pp. 106-7. (Reactive airway disease and management.)

Gulleth, Y, Spiro, J. “Percutaneous transtracheal jet ventilation in head and neck surgery”. Arch Otolaryngol Head Neck Surg . vol. 131. 2005. pp. 886-90. (Discusses the use and safety of transtracheal jet ventilation in surgery.)

Langerman, A, MacCracken, E, Kasza, K, Haraf, DJ, Vokes, EE, Stenson, KM. “Aspiration in chemoradiated patients with head and neck cancer”. Arch Otolaryngol Head Neck Surg . vol. 133. 2007. pp. 1289-95. (Discusses aspiration risks in chemoradiated head and neck cancer patients).

Dean, NR, Rosenthal, EL, Carroll, WR, Kostrzewa, JP, Jones, VL, Desmond, RA, Clemons, L, Magnuson, S. “Robotic-assisted surgery for primary or recurrent oropharyngeal carcinoma”. Arch Otolaryngol Head Neck Surg . vol. 136. 2010. pp. 380-4. (Discusses robotic surgery for head and neck cancer and its benefits over conventional surgery.)

Farwell, DG, Reilly, DF, Weymuller, EA, Greenberg, DL, Staiger, TO, Futran, NA. “Predictors of perioperative complications in head and neck patients”. Arch Otolaryngol Head Neck Surg. vol. 128. 2002. pp. 505-11. (Discusses the predictors of complications in head and neck surgery and strategies to minimize them.)

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