Total hip endoprostheses--characteristic aspects from the anesthesiologic viewpoint

Abstract

Total hip replacement is a frequently practised operation. Depending on age, circumstances and individual assessment, cemented, non-cemented and hybrid forms are used. Apart from general risks, such as vascular and/or neural injuries, thrombosis and infections, there are specific risks, depending on the surgical technique. If cemented systems are used, the anesthesiologist must be on the alert in respect of a possible multi-causal cardiopulmonary depression during the implantation of the prosthesis. Incidents may be reduced or moderated by measures such as reduction of pressure from the femoral cavity or anesthetic measures such as avoidance of N2O during or after cementation, use of anti-histamines, etc., but there is no absolute protection from severe reactions by the cardiopulmonary system. In these cases it is imperative to recognise and treat hypoxic conditions immediately, whatever the cause, such as cardiac or pulmonary depression. If a non-cemented hip replacement is used or a revision is necessary the main problem is usually a higher blood loss. Especially in such cases it is necessary to apply a well-organised sequence of blood-saving methods to protect patients from the general risks of homologous blood transfusion. Even though the main concern of the public is the possibility of contamination of donor blood with the AIDS virus, transmission of hepatitis C virus is a much more common problem. Depending on the diagnostic methods the occurrence of thrombosis after total hip replacement has been reported to be as much as 55%. To minimise this high incidence, sufficient prophylaxis, adequate fluid therapy, suitable anesthetic techniques and cutting down on the duration of the operation should be taken into account. The use of low molecular weight heparins has certain advantages. If deep vein thrombosis has occurred, therapy consists of anticoagulation with intravenous heparin and immobilisation. A rare but severe complication is a deep hip prosthetic infection. More than 50% of infections are caused by coagulase-negative staphylococci and anaerobic bacteria. To avoid sepsis it is imperative to employ adequate high-dosage antibiotics, revisional surgery and, if necessary, even excision arthroplasty. There is no "ideal" anesthesiological method for total hip replacement. Regional techniques as well as general anesthesia have their specific pros and cons which are controversially discussed in respect of their priority. To achieve early diagnosis of embolism, especially in the case of high risk patients, the exigency of extensive haemodynamic monitoring as well as Doppler-ultrasound is discussed.(ABSTRACT TRUNCATED AT 400 WORDS)