Perioperative management of obstructive sleep apnea

Obstructive sleep apnea (OSA) is the most common breathing disorder, with a high prevalence in both the general and surgical populations. OSA is frequently undiagnosed, and the initial recognition often occurs during medical evaluation undertaken to prepare for surgery. Adverse respiratory and cardiovascular outcomes are associated with OSA in the perioperative period; therefore, it is imperative to identify and treat patients at high risk for the disease. In this review, we discuss the epidemiology of OSA in the surgical population and examine the available data on perioperative outcomes. We also review the identification of high-risk patients using clinical screening tools and suggest intraoperative and postoperative treatment regimens. Additionally, the role of continuous positive airway pressure in perioperative management of OSA and a brief discussion of ambulatory surgery in patients with OSA is provided. Finally, an algorithm to guide perioperative management is suggested.     

Contractility and ultrastructure of cardiac muscle of guinea pigs treated with diphtheria toxin

Summary The development of tension and the ultrastructure of cardiac papillary muscle of normal guinea pigs were compared to guinea pigs receiving lethal doses of diphtheria toxin. The maximal isometric force of the papillary muscles at various levels of resting tension indicated no significant difference between the control and the diphtheritic animals. Neither did the sarcomere lengths of papillary muscles, fixed at various levels of tension, show any Significant difference between these two groups. Electronmicroscopy in diphtheritic animals showed intact myofilaments but marked dilatation of theT andL system as well as pathologic fat deposits adjacent to the subsarcolemma and theT system. The results, therefore, suggest that diphtheria toxin acts on theT andL system, but does not affect structure and function of the myofilaments in the acute stage of diphtheria intoxication.Supported by the Deutsche Forschungsgemeinschaft.Dedicated to Prof. W. Doerr on occasion of his 60th birthday.We wish to thank Mrs. K. Mews and Mr. H. Derks for their unfailing technical assistance. Behringwerke A.G., Marburg/Lahn, kindly gave us a supply of diphtheria toxin.     

Epidemiology of urticaria diseases

In a prospective analysis, all patients presenting with urticaria in the practices of a general practitioner and a dermatologist and at a university clinic in the course of a year were ascertained and underwent diagnostic examination according to a uniform scheme. Urticarias are common skin diseases, affecting, at a modest estimate, about 1.3% of the population. Of all the general practitioner's patients about 3% had one of the many types of urticaria. The same percentage was found in the dermatologist's practice and among the patients attending the university clinic. The incidence of the different types of urticaria differs considerably at the different levels of medical care. This may be due to the fact that the patients are referred to a specialist or to a clinic only when the diagnosis or treatment is problematic. Half the general practitioner's urticaria patients suffer from physical urticarias (this includes the minor variants that do not necessarily require medical care). In the clinic, however, only a quarter of all patients with urticaria had physical variants. Patients with chronic urticaria accumulate in clinics because they have been referred for diagnosis and therapy. Predominantly young people were affected by physical urticaria, the peak being between 10 and 40 years. Patients with chronic "endogenous" urticaria were significantly older. About 30% of all patients also had angio-oedema, at least temporarily. Isolated swelling without urticaria occurred in only 3.9% of all patients. In urticaria, there was a slight female predominance: of all patients with physical urticaria, 61.1% were female, and the corresponding figure for nonphysical types was 53.6%. An almost equal sex distribution was found in chronic urticaria (51.9% female). In our prospective study patients presenting with urticaria only as a minor symptom was also ascertained. Many minor variants of physical urticaria were seen in these patients. In the dermatological practice, urticaria was diagnosed incidentally in 6-8% of cases. In the clinic, however, 20% of the physical urticarias and 10% of the acute nonphysical urticarias were recorded as incidental findings.     

Point-of-care testing for prothrombin time, but not activated partial thromboplastin time, correlates with laboratory methods in patients receiving aprotinin or epsilon-aminocaproic acid while undergoing cardiac surgery.

Point-of-care testing (POCT) of coagulation parameters can help optimize transfusion practice in cardiac surgery. Antifibrinolytic agents may interfere with the laboratory and/or POCT coagulation assays. This randomized controlled study compared coagulation parameters obtained from a whole blood POCT coagulation device with a typical laboratory instrument in cardiac surgery patients receiving aprotinin, epsilon-aminocaproic acid, or normal saline before undergoing cardiopulmonary bypass. Aliquots of arterial blood samples from 42 patients were collected perioperatively, and their prothrombin times (PTs) and activated partial thromboplastin times (aPTTs) were measured by POCT and laboratory instrumentation. Linear regression and error analyses were used for the method comparison. For PT, the POCT device compared favorably with the laboratory method. For aPTT, the POCT device did not compare well with the laboratory method. Treatment with antifibrinolytic agents does not interfere with determination of PT.     

Remifentanil versus meperidine for monitored anesthesia care: a comparison study in older patients undergoing ambulatory colonoscopy

Colonoscopy is one of the most frequently performed outpatient procedures in the United States. This study was designed to test the hypothesis that a remifentanil infusion would be superior to boluses of meperidine in older patients undergoing ambulatory colonoscopy. One hundred ASA physical status I-IV patients undergoing colonoscopy were randomized in this double-blinded study to receive either remifentanil infusions (n = 49) or titrated boluses of meperidine (n = 51). Patient tolerance was assessed using physiologic variables and side effects associated with opioid analgesia. Verbal pain/anxiety and patient/operator satisfaction were also assessed. As a group, the physiologic characteristics demonstrated no significant differences in the response to the colonoscopy procedure. Although the patient and operator satisfaction surveys were similar between groups, the incidences of tachycardia, hypotension, and nausea were less and the adjusted verbal pain and anxiety scores were more in the Remifentanil group compared with the Meperidine group. This study demonstrates that remifentanil and meperidine were equally well tolerated in older patients undergoing ambulatory colonoscopy when administered by an anesthesia provider. The differences in the pharmakinetics of remifentanil and meperidine most likely account for the differences noted between the two treatment groups. Implications: Remifentanil infusions and meperidine boluses are equally well tolerated in older patients undergoing ambulatory colonoscopy when administered by an anesthesia provider.