Philip D. Lumb

Pressure support ventilation with the laryngeal mask airway: a method to manage severe reactive airway disease postoperatively

The use of a laryngeal mask airway (LMA) and a bi-level positive airway pressure (BiPAP®) machine is described in a postoperative thoracotomy patient with reactive airway disease. The LMA was placed to avoid reintubation of the trachea after a double lumen tube was no longer necessary. Placement in an awakening patient and positive-pressure ventilatory support were well tolerated and did not trigger a bronchospastic response. The patient was able to cough and breathe deeply with the LMA while receiving ventilatory assistance in the postanaesthesia care unit (PACU). The LMA is a therapeutic option to tracheal reintubation in patients who need postoperative ventilatory support after one-lung anaesthesia.RésuméLe masque laryngé (ML) associé à un appareil de pression positive à deux paliers (BIPAP®) est utilisé après une thoracotomie chez un patient souffrant d’une hyperéactivité des voies respiratoires. Le ML est installé pour éviter une réintubation trachéale après l’ablation de la canule bronchique à deux lumières. La mise en place en phase de réveil et l’aide ventilatoire sont bien tolérées et ne déclenchent pas de bronchospasme. A l’unité de soins postanesthésique, le patient est capable de tousser et de respirer profondément avec un ML. Le ML peut remplacer la réintubation trachéale chez les patients dont l’état nécessite une assistance ventilatoire après une anesthésie unipulmonaire.

A phase III, multicenter, open-label, randomized, comparative study evaluating the effect of sevoflurane versus isoflurane on the maintenance of anesthesia in adult ASA class I, II, and III inpatients

STUDY OBJECTIVE To compare the clinical efficacy and safety of sevoflurane and isoflurane when used for the maintenance of anesthesia in adult ASA I, II, and III inpatients undergoing surgical procedures of at least 1 hours duration. DESIGN Phase III, randomized, open-label clinical trial. SETTING 12 international surgical units. PATIENTS 555 consenting inpatients undergoing surgeries of intermediate duration. INTERVENTIONS Subjects received either sevoflurane (n = 272) or isoflurane (n = 283) as their primary anesthetic drug, each administered in nitrous oxide (N2O) (up to 70%) and oxygen (O2) after an intravenous induction using thiopental and low-dose fentanyl. The concentration of volatile drug was kept relatively constant but some titration in response to clinical variable was permitted. Comparison of efficacy was based on observations made of the rapidly and ease of recovery from anesthesia and the frequency of untoward effects for the duration of anesthesia in the return of orientation. Safety was evaluated by monitoring adverse experiences, hematologic and non-laboratory testing, and physical assessments. In 25% of patients (all patients 171 both treatment groups at selected investigational sites), plasma inorganic fluoride concentrations were determined preoperatively, every 2 hours during maintenance, at the end of anesthesia, and at 1, 2, 4, 8, 12, 24, 48, and 72 hours postoperatively. MEASUREMENTS AND MAIN RESULTS Emergence, response to commands, orientation, and the first request for postoperative analgesia were all more rapid following discontinuation of sevoflurane than following discontinuation of isoflurane (sevoflurane, 11.0 +/- 0.6, 12.8 +/- 0.7, 17.2 +/- 0.9, 46.1 +/- 3.0 minutes, respectively, versus isoflurane, 16.4 +/- 0.6, 18.4 +/- 0.7, 24.7 +/- 0.9, 55.4 +/- 3.2 minutes). The incidence of adverse experiences was similar for sevoflurane and isoflurane patients. Forty-eight percent of patients on the sevoflurane group had no untoward effect versus 39% in the isoflurane group. Three patients who received sevoflurane had serum inorganic fluoride levels 50 microM/I. or greater though standard tests indicated no evidence of associated renal dysfunction. CONCLUSION Sevoflurane anesthesia, as compared with isoflurane, may be advantageous in providing a smoother clinical course with a more rapid recover.

Low-Dose Heparin Appears Safe and Can Eliminate Protamine Use for Carotid Endarterectomy

OBJECTIVE To determine the morbidity associated with carotid endarterectomy (CEA) when low doses of heparin (30 U/kg) are used for anticoagulation. This technique eliminates the need for protamine and its potentially deleterious effects on some patients. DESIGN A retrospective chart review. SETTING A large academic medical center. PARTICIPANTS The records of 420 consecutive CEAs in 337 patients (83 bilateral procedures). INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS The amount of heparin used was less than that used in most reported studies. Eighty-two percent of patients received only 2,000 U of heparin for their entire operation (range, 500 to 3,000 U). Complication rates were low. Neurologic complications included a 0.95% incidence of nonfatal stroke and a 2.1% incidence of transient neurologic deficits that resolved in the first day. There was no mortality. The wounds were described in the postoperative period as dry (96%), swollen (3%), or bloody (1%). No patients received protamine. CONCLUSION The use of 5 to 10,000 U of heparin will provide anticoagulation for more than an hour. In CEA surgery, anticoagulation for this duration is often unnecessary. A smaller dose of heparin (30 U/kg) can provide adequate anticoagulation for this procedure while eliminating the potentially deleterious effects of protamine use. No additional morbidity was attributed to this technique.

Anesthetic management for myocardial revascularization following bleomycin chemotherapy.

B LEOMYCIN (BLM) is a glycoprotein antibiotic synthesized from Streptomyces verticillus that is highly effective against malignancies such as lymphomas, dysgenetic testicular tumors, and squamous cell carcinomas. It is often used in conjunction with other agents because of its low potential for bone marrow suppression or immunosuppression, thereby enhancing the antineoplastic effect at the cost of fewer side effects.’ Pulmonary toxicity that presents as an interstitial pneumonitis that may progress to fibrosis is its major side effect.* Patients more than 65 years of age and those with persisting pulmonary pathology are especially at risk. Pulmonary fibrosis occurs in 3% of patients receiving BLM. A hypersensitivity pneumonitis and fulminant respiratory failure can also occur.3 Asymptomatic changes in pulmonary function that may be construed as milder forms of toxicity are probably more common.4,5 Radiation to the chest and oxygen therapy are believed to potentiate BLM pulmonary toxicity. A high or even modestly elevated F,02 (0.33) has been thought to be responsible for postoperative respiratory failure and subsequent deaths.‘.6 In addition, exacerbations of recognized or occult pulmonary fibrosis may occur with other antineoplastic agents (eg, busulfan, methotrexate, cyclophosphamide) following 0, therapy.‘.’ The anesthesiologist may be required to manage a case for the removal of retroperitoneal lymph nodes or pulmonary metastasis following BLM chemotherapy. Even if the lymph nodes show no metastatic disease, they are large, fibrotic, sclerotic, and often attached to neighboring structures. This makes surgery technically difficult, prolonged, accompanied by considerable blood loss, and may involve the resection of the large bowel, aorta, inferior vena cava, or a kidney.6 Resection of pulmonary metastases has the potential problem of the need for one-lung anesthesia during thoracotomy, and the consequent risk of the use of an increased F,O, to avoid hypoxia. A patient who may have been at risk for reactivation of BLM lung toxicity when he underwent myocardial revascularization during hypothermic cardiopulmonary bypass (CPB) is reported. The use of an Oximetric pulmonary artery catheter (PAC) in combination with peripheral pulse oximetry ensured adequate oxygenation while the patient received restricted 0, therapy during and after surgery.

Prevention and Management of Metabolic Alkalosis.

Metabolic alkalosis is the most common acid-base disor der seen in hospitalized patients. There are three types of metabolic alkalosis: chloride responsive, chloride re sistant, and exogenous administration of alkali. Chlo ride-responsive alkalosis is the most common. Metabolic alkalosis can result in numerous metabolic abnormalities as well as cardiovascular and neurological dysfunction. Histamine H2-receptor antagonists are im portant in the prevention, control, and acute treatment of chloride-responsive metabolic alkalosis. In most pa tients chloride-responsive metabolic alkalosis can be managed successfully with fluid therapy and H 2-recep tor antagonists or a carbonic anhydrase inhibitor (for example, acetazolamide).

Cardiopulmonary bypass: Risk management concerns for the anesthesiologist

Perfusionists have a critically important role in cardiac surgery. Their responsibilities include providing cardiovascular support, maintaining adequate blood flow and blood pressure, maintaining adequate oxygenation, operating suction pumps and other devices, regulating blood temperature, and keeping records. The relationship between perfusionist and anesthesiologist as members of the cardiac surgical team should be one of mutual support. Although many anesthesiologists do not control the pharmacology of perfusion, it is their responsibility to ensure that the perfusionist understands the pharmacopeia being used and to know what the perfusionist is administering. In-depth knowledge of the techniques and practices of cardiopulmonary perfusion is a prerequisite for cardiac anesthesiologists. The future is likely to see an increasingly supportive relationship between anesthesiologists and perfusionists.

Management of Hospital-acquired Complications in Critically Ill Patients

of gastric fluid versus the amount vomited and subsequently entering the tracheobronchial tree. It is unlikely that aspiration of any gastric fluid is truly benign. Certainly one strategy appears clear: to decrease the morbidity and mortality associated with this syndrome, one must promptly consider and institute prophylaxis rather than later face management of aspiration pneumonitis. The popularity of prophylaxis to diminish the incidence of and problems associated with stress ulcer-related bleeding in critical care medicine is