The principal risk factors for this type of cancer are smoking and alcohol, which appear to have a synergistic effect. Chewing tobacco, poor oral hygiene, and exposure to wood dust are additional risk factors.
The incidence of head and neck cancers has increased in the past decade because of the emergence of human papilloma virus transmission linked to orogenital sex. Ideally, all head and neck cancer patients should be assessed by a multidisciplinary team of specialists. The aim of preoperative assessment is to identify patients with potentially difficult airways, stratify the risks, treat co-morbidities, and optimize their physiology before major surgery.
The incidence of difficult airways in head and neck cancer is higher than in the general population. Evaluation of the airway should include an assessment of the difficulty in intubation and the feasibility of appropriate rescue plans in achieving oxygenation. Subtle changes to the voice, dysphagia, orthopnoea, and recent onset of snoring may indicate airway compromise. In slowly progressive cancer, with conditioning of the respiratory muscles, patients may have few signs or symptoms, despite significant narrowing of the airway.
Radiological imaging with computed tomography or magnetic resonance imaging MRI helps to determine the extent of the cancer and the impact of the pathology and potential obstruction.
In experienced hands, ultrasonography is useful in identifying the cricothyroid membrane before induction of anaesthesia Fig. Awake nasal endoscopy can be carried out before induction of anaesthesia and is especially useful when no other radiological investigations are available. It gives a real-time view of the upper airway and the larynx and is useful in identifying patients in whom an awake technique is more appropriate. Parasagittal ultrasound of the neck showing tracheal rings string of pearls and the cricothyroid membrane. Head and neck cancer patients often have significant cardiorespiratory disease and poor nutritional states linked with smoking and excessive alcohol consumption.
The perioperative risk associated with major surgery increases with advancing age and the increasing number of co-morbidities. The potential benefit of the surgery must be weighed against its risks; this is where anaesthetists play a vital part in deciding the treatment plan as part of the multidisciplinary team. Baseline investigations include full blood count, clotting screen, biochemical profile with urea and electrolytes, liver function test, blood sugar, and electrocardiography.
Further investigations such as chest X-ray, pulmonary function tests, arterial blood gases, and echocardiogram should be requested based on the risk factors and symptoms at presentation. Chronic obstructive pulmonary disease COPD is common in head and neck cancer patients and any reversible element should be optimised before surgery by modification of bronchodilator therapy, treatment of acute infection, and trial of steroids.
Flow volume loops generated during pulmonary function testing can be used to differentiate dyspnoea from upper airway obstruction and chronic airways disease. For example, in comparison with the single plateau of the expiratory limb in COPD, plateaus can be seen in both the inspiratory and the expiratory limbs during fixed upper airway obstruction Fig. However, reproducible spirometry data depend on patient cooperation and coordination in addition to an encouraging, well-trained respiratory technician.
Flow volume loops: A normal inspiratory and expiratory limb, B the slowing and flattening of the expiratory limb in COPD, and C fixed upper airway obstruction showing plateaus in both the inspiratory and the expiratory limbs. The calculation of metabolic equivalent based on self-reported functional capacity is subjective and high-risk patients cannot be identified by this method alone.
Cardiac biomarkers such as brain natriuretic peptide BNP and N-terminal proBNP are useful in screening for heart failure and are independently predictive of day cardiac mortality. Preoperative malnutrition independently correlates with poor wound healing, infection, and increased risk of postoperative complications. Patients may be malnourished from poor dietary habits e. The UK head and neck cancer guidelines recommend that all patients have nutritional screening by a clinician at presentation and specialist dietician input throughout their care. The nutritional support depends on the extent of the tumour, planned surgical procedure, and social support.
This ranges from oral supplements to percutaneous gastrostomy.
The incidence of refeeding syndrome as a result of reintroduction of feeds is high in head and neck cancer patients. A management plan for refeeding syndrome is presented in Table 1. Table 1 Management of refeeding syndrome. Scoring systems, such as P-POSSUM Portsmouth—Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity , which have been extensively validated in colorectal and vascular surgery, do not accurately predict risk in head and neck cancer patients.
The UK multidisciplinary head and neck cancer guidelines recommend using the Revised Lee Cardiac Risk Index to predict cardiac risk in the perioperative period. Management should start with all the available imaging being reviewed jointly by the surgeon and the anaesthetist. The airway that was initially straightforward during a previous anaesthetic may have deteriorated because of the spread of the disease or as a result of treatment Table 2.
Table 2 Sequelae of head and neck cancer treatment. Preoperative evaluation should establish: If face mask ventilation is likely following induction of general anaesthesia?
Management depends on the clinical presentation, individual expertise, and the available equipment. It is essential that anaesthetists are aware of human factors, maintain situational awareness, avoid task fixation, and do not resort to unfamiliar techniques. A coordinated team approach with clear communication is essential. In head and neck cancers, airway difficulty is expected and should be planned for.
The first step is to determine whether intubation is possible after induction of general anaesthesia or whether it would be achieved more safely with an awake technique. When difficulty in tracheal intubation and bag-mask ventilation is predicted or has been experienced previously, awake intubation should be considered. An awake approach potentially offers advantages of maintenance of airway patency, gas exchange, and protection against aspiration during the intubation process.
General anaesthesia worsens airway obstruction, making identification of landmarks difficult on endoscopy. Fibreoptic intubation after induction of general anaesthesia will not always be successful in patients in whom an awake intubation is indicated. Awake tracheostomy under local anaesthesia should be strongly considered as a primary plan in patients with significant obstruction where awake fibreoptic intubation is not feasible.
The theoretical advantage of gas induction is that it is a slow induction that preserves spontaneous ventilation, and if at any point airway obstruction does occur, then the delivery of the inhaled anaesthetic ceases and the patient can theoretically wake up. The NAP-4 report highlighted that, in practice, when total airway obstruction occurs, patients do not exhale the anaesthetic gases and hypoxia rapidly ensues.
If direct laryngoscopy fails, then this should be accepted, clearly communicated to the team, and the predetermined backup plan put in place. Repeated attempts at direct laryngoscopy risks bleeding and trauma in necrotic, friable tumours and may lead to complete airway obstruction.
Limited evidence exists on the use of video laryngoscopes in head and neck cancers. There is an overlap in predictive markers of difficulty with direct laryngoscopy with previous radiotherapy, malignancy, and previous surgery also leading to difficulty in intubation using video laryngoscopes. Rescue oxygenation techniques must also be discussed at the start with the theatre team, in case the primary plan fails.
The rescue plans may include face mask ventilation, supraglottic ventilation, or a surgical airway. It is essential to bear in mind that insertion and placement of supraglottic airway devices is difficult in patients with trismus, oropharyngeal lesions, and after radiotherapy. Trans-nasal high-flow rapid insufflation ventilatory exchange THRIVE is useful in maintaining oxygen saturation and prolonging the apnoeic window in attempts to secure the airway.
Surgical tracheostomy is essential for the postoperative period when swelling and oedema can lead to airway compromise. All Rights Reserved. Twitter Facebook Email. This Issue.
To reduce the likelihood of complications, Dr. Park said the anesthesia team should be in constant communication with the surgical team and vice versa. Certain cases of free-flap surgeries can take as little as four or five hours, while others take up to 10 to 12 hours. If the anesthesia team knows an approximate time up front, perhaps they will not be as aggressive in administering certain medications or fluids or transfusions. Consequently, Dr. Park encouraged high-volume centers flaps annually to investigate for themselves the effects of anesthesia duration over a five-year study period, using more detailed and accurate patient records.