Perioperative evaluation of myasthenia gravis.

Myasthenia gravis (MG) is the prototype of antibody mediated autoimmune disease and results from the production of autoantibodies against the acetylcholine receptor (AChR) of the neuromuscular synapse. Adequate preoperative evaluation of the myasthenic patient must be carried out carefully. Age, sex, onset and duration of the disease as well as the presence of thymoma may determine the response to thymectomy. Specific attention should be paid to voluntary and respiratory muscle strength. The preoperative preparation of MG patients is essential for the success of surgery. It depends on the severity of clinical status and changes if myasthenic patients receive anticholinesterase therapy. Myasthenic patients may have little respiratory reserve, and hence depressant drugs for preoperative premedication should be used with caution and avoided in patients with bulbar symptoms. The anaesthetic management of myasthenic patient must be individualized in according to the severity of the disease and the type of surgery required. The use of regional or local anaesthesia seems warranted whenever possible. General anaesthesia can be performed safely when patient is optimally prepared and neuromuscular transmission is adequately monitored during and after surgery. Adequate postoperative pain control, pulmonary toilet, and avoidance of drugs that interfere with neuromuscular transmission will facilitate tracheal extubation. Myasthenia gravis is a disease with many implications for the safe administration of anaesthesia. The potential for respiratory compromise in these patients requires the anaesthesiologist to be familiar with the underlying disease state, as well as the interaction of anaesthetic and non-anaesthetic drugs with MG.

Perioperative management of thymectomy.

Thymoma is the most frequent type of tumor in the anterior-superior mediastinum. The presentation of thymomas is variable; most are asymptomatic and others present themselves with local compression syndrome or parathymic syndrome; rarely thymomas appear as an acute emergency. Surgery is the treatment of choice for thymic tumors and complete resection is the most important prognostic factor. Surgery with adjuvant radiation is recommended for invasive thymoma. The anaesthetic management of patients with mediastinal thymoma undergoing thymectomy is associated with several risks related to potential airway obstruction, hypoxia and cardiovascular collapse. Patients at high risk of perioperative complications can be identified by the presence of cardiopulmonary signs and symptoms. However, asymptomatic thymomas have been occurred with acute cardiorespiratory complications under general anaesthesia. A careful preoperative evaluation of signs, symptoms, chest X-ray, CT scan, MRI, cardiac echogram and venous angiogram should be helpful to investigate neoplasm presence and the area of invasion; moreover, an adequate airway and cardiovascular management, such as performing an awake intubation in the sitting position, allowing spontaneous and non-controlled ventilation, a rigid bronchoscope available and a standby cardiopulmonary bypass, is suggested to prevent the main life-threatening cardiorespiratory complications.

Postoperative management of elective esophagectomy for cancer.

Postoperative management after elective esophagectomy for cancer has not been standardized. Thoracoabdominal incision with associated pain, extended operative time with consequent extracellular fluid shifts, single lung ventilation, potential for prolonged postoperative mechanical ventilation and comorbidities in patients with esophageal cancer, all contribute to high perioperative risk. Respiratory problems remain the major cause of both mortality and morbidity after esophagectomy for cancer. A specific pulmonary disorder, acute respiratory distress syndrome (ARDS) occurs in 10-20% of patients after esophagectomy. ARDS mortality exceeds 50%. Atrial fibrillation, that complicates recovery in 20 to 25% of patients after esophagectomy, contributes to make outcome worse. Anesthesiologists should adopt strategies known to be able to optimize patient outcome. Decreased postoperative mortality and morbidity have been associated with epidural analgesia, bronchoscopy to clear persistent bronchial secretions, intraoperative fluid restriction and early extubation. It has been shown that setting up early respiratory physiotherapy and mobilitation may improve functional recovery.

Preoperative evaluation and risk factors in patients undergoing lung resection for cancer.

Surgical resection remains the mainstay of treatment in lung cancer patients. Stratification of preoperative risk should be based on the functional status of pulmonary and cardiac systems usually damaged by cigarette smoking. Preoperative pulmonary evaluation should be performed taking into consideration the specific characteristics of the single patient and the type of surgery planned. Spirometry only may be required or oxygen consumption determination is necessary. Cardiac assessment should be based on clinical and instrumental examinations while invasive tests should be limited to high-risk patients. The potential difficulties in endotracheal intubation and lung isolation, the risk for desaturation during one-lung ventilation, and postoperative pain control should be analyzed.