Anaesthetic Implications of Chemotherapy
Anaesthetic Implications of Chemotherapy
Bleomycin is a particularly important chemotherapy drug for the anaesthetist to be aware of. Bleomycin is often used to treat germ cell tumours and Hodgkin's disease in a curative setting. The major limitation of bleomycin therapy is the potential for subacute pulmonary damage that can progress to life-threatening pulmonary fibrosis. Pulmonary toxicity occurs in 6–10% patients and can be fatal. Exposure to high-inspired concentration oxygen therapy, even for short periods, as experienced during anaesthesia, is often implicated in causing rapidly progressive pulmonary toxicity in patients previously treated with bleomycin. These claims have been considered controversial by some, but it is the authors' recommendation that any patient previously exposed to bleomycin therapy should be treated as high risk, and summary guidance regarding oxygen therapy is shown in Table 4.
Bleomycin-induced lung injury typically occurs insidiously during the first 6 months after starting treatment, but the potential for high-inspired fractions of oxygen to provoke pulmonary toxicity remains a life-long risk. All patients who have ever received bleomycin should wear an alert card and an alert sticker should be placed on their notes.
The symptoms of bleomycin-induced pulmonary toxicity are non-specific and include dry cough and breathlessness. Patients may also experience pleuritic chest pain and fever. On examination, pulmonary crackles and hypoxaemia may be found. The diagnosis of bleomycin toxicity must be considered in all respiratory illnesses in patients who have ever received bleomycin.
Bleomycin toxicity has typical appearances radiologically:
There are particular concerns for patients who are undergoing surgery and who have been treated with bleomycin. Oxygen therapy can both induce and exacerbate bleomycin lung injury. A high concentration of inspired oxygen increases the risk of developing bleomycin-induced lung injury and a lower inspired oxygen concentration reduces the risk. When bleomycin has been administered preoperatively, reduced oxygen concentrations should be used during anaesthesia and postoperatively.
Pre-assessment of a patient with previous bleomycin exposure will require a thorough history and examination. Depending upon clinical findings, investigations required may include a chest X-ray, arterial blood gases, lung computed tomography, pulmonary function tests, and bronchoscopy. Oxygen should be prescribed on the drug chart, and the dose of oxygen adjusted frequently to maintain the minimum exposure to achieve a target range of peripheral oxygen saturation between 88% and 92%. If oxygen saturations are higher than this, then oxygen should be stopped or the dose reduced. Ventilatory strategies involving the use of PEEP and careful fluid balance will limit the amount of oxygen required.
Postoperatively, chest physiotherapy, good analgesic regimes, and early mobilization also minimize the requirement for oxygen.
Bleomycin
Bleomycin is a particularly important chemotherapy drug for the anaesthetist to be aware of. Bleomycin is often used to treat germ cell tumours and Hodgkin's disease in a curative setting. The major limitation of bleomycin therapy is the potential for subacute pulmonary damage that can progress to life-threatening pulmonary fibrosis. Pulmonary toxicity occurs in 6–10% patients and can be fatal. Exposure to high-inspired concentration oxygen therapy, even for short periods, as experienced during anaesthesia, is often implicated in causing rapidly progressive pulmonary toxicity in patients previously treated with bleomycin. These claims have been considered controversial by some, but it is the authors' recommendation that any patient previously exposed to bleomycin therapy should be treated as high risk, and summary guidance regarding oxygen therapy is shown in Table 4.
Bleomycin-induced lung injury typically occurs insidiously during the first 6 months after starting treatment, but the potential for high-inspired fractions of oxygen to provoke pulmonary toxicity remains a life-long risk. All patients who have ever received bleomycin should wear an alert card and an alert sticker should be placed on their notes.
The symptoms of bleomycin-induced pulmonary toxicity are non-specific and include dry cough and breathlessness. Patients may also experience pleuritic chest pain and fever. On examination, pulmonary crackles and hypoxaemia may be found. The diagnosis of bleomycin toxicity must be considered in all respiratory illnesses in patients who have ever received bleomycin.
Bleomycin toxicity has typical appearances radiologically:
Linear interstitial shadowing may be seen, which can look similar to Kerly B lines seen in pulmonary oedema.
Confluent airspace shadowing may be present, which may be diagnosed as infection if the diagnosis of bleomycin lung injury is not considered.
Pneumothorax and pneumomediastinum are recognized complications in severe bleomycin lung injury.
There are particular concerns for patients who are undergoing surgery and who have been treated with bleomycin. Oxygen therapy can both induce and exacerbate bleomycin lung injury. A high concentration of inspired oxygen increases the risk of developing bleomycin-induced lung injury and a lower inspired oxygen concentration reduces the risk. When bleomycin has been administered preoperatively, reduced oxygen concentrations should be used during anaesthesia and postoperatively.
Pre-assessment of a patient with previous bleomycin exposure will require a thorough history and examination. Depending upon clinical findings, investigations required may include a chest X-ray, arterial blood gases, lung computed tomography, pulmonary function tests, and bronchoscopy. Oxygen should be prescribed on the drug chart, and the dose of oxygen adjusted frequently to maintain the minimum exposure to achieve a target range of peripheral oxygen saturation between 88% and 92%. If oxygen saturations are higher than this, then oxygen should be stopped or the dose reduced. Ventilatory strategies involving the use of PEEP and careful fluid balance will limit the amount of oxygen required.
Postoperatively, chest physiotherapy, good analgesic regimes, and early mobilization also minimize the requirement for oxygen.
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