Relevance of Respiratory Disorders in the Provision of Local Anaesthesia Sedation, General Anaesthesia and Management in Dental Practice

Relevance of Respiratory Disorders in the Provision of Local Anaesthesia Sedation, General Anaesthesia and Management in Dental Practice 

Excellent dental care is important in patients with respiratory disorders. There is some evidence of an association of poor dental health with pneumonia and COPD. In addition there is good evidence that improvements in oral hygiene can reduce the impact of respiratory disease in high-risk individuals [10]. The relevant drug interactions and adverse effects of medication used to treat respiratory disorders have been discussed above. Other effects of respiratory disease on management are considered here. In the presence of respiratory impairment, general anaesthesia can be potentially dangerous since respiratory failure may be precipitated. If infection is temporary, then resolution should be awaited. If GA is unavoidable and the condition is chronic, e.g. in cases of COPD or bronchiectasis, then the condition of the patient should be optimised, e.g. using preoperative physiotherapy, sometimes antibiotics, bronchodilators such as salbutamol and antimuscarinics such as ipratropium (sometimes nebulised). Even when treated using LA, these patients may become dyspnoeic, especially when supine. As part of any preoperative workup, benefit can be gained by stopping smoking. The use of rubber dam may be unacceptable in patients with COPD due to further compromise of the airway. If rubber dam is necessary, supplemental oxygen via a nasal cannula may be required, but low concentrations should be used. Figure 3.5 shows a patient receiving supplemental oxygen via a nasal cannula. In cases of active TB, a GA is contraindicated, both due to impaired respiratory function or contamination of anaesthetic machine circuits. Asthmatic patients should have treatment carried out using LA if possible. Effort should be made to allay anxiety as far as possible, and treatment should not be carried out if the patient has not brought their normal medication and such medication is otherwise unavailable. Relative analgesia using nitrous oxide and oxygen is preferred to intravenous sedation since the former can be rapidly controlled. GA can be complicated by hypoxia and increased carbon dioxide which can lead to pulmonary oedema even if cardiac function is normal. As mentioned above patients may not be comfortable in the supine position if they have respiratory problems. If the patient suffers from asthma, then aspirin-like compounds should not be prescribed as many asthmatic patients are allergic to these analgesics [11]. A severe asthmatic attack can be life-threatening, and as stress may contribute to the onset of such a condition, the dentist should have the equipment to deal with such an emergency at hand. A salbutamol inhaler or nebulised salbutamol is useful.

Intravenous hydrocortisone and intravenous aminophylline are reserved for patients who do not respond quickly to nebulised bronchodilator therapy. Care is needed with patients already taking theophylline preparations, and this step is best left until medical assistance is available. The use of supplemental steroids prior to dental surgery in patients at risk of an ‘adrenal crisis’ is still a contentious issue although many cases that in the past would have had steroid supplementation are now treated by monitoring the blood pressure during the procedure; see below. The rationale for steroid supplementation is as described below. Corticosteroids are critical in the body’s response to trauma (including operative trauma). A normal response is to increase corticosteroid production in response to stress. If this response is absent, hypotension, collapse and death will occur. The hypothalamic-pituitary-adrenal axis will fail to function if either pituitary or adrenal cortex ceases to function, e.g. administration of corticosteroids, leads to negative feedback to the hypothalamus causing decreased ACTH production and adrenocortical atrophy. This atrophy means that an endogenous steroid boost cannot be produced in response to stress. Studies have suggested that dental surgery may not require supplementation [12]. More invasive procedures, however, such as third molar surgery or the treatment of very apprehensive patients, may still require cover. It is wise, even if supplementary steroids have not been used, to monitor the blood pressure of patients taking steroids. If the diastolic pressure falls by more than 25%, then a steroid injection (100  mg hydrocortisone) is indicated. Patients who may require supplementation are those who are currently taking corticosteroids or have