Der Anaesthesist
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Review
[Clinical studies on the peripheral effect of opioids following knee surgery. A literature review].
In this article 34 randomized controlled trials examining peripherally mediated opioid effects after knee surgery are discussed. All studies examined small doses of morphine injected intraarticularly at the end of knee surgery, but not all studies did show an analgesic effect of the peripheral opioid. Because of differing study designs a meta-analysis of the data is not possible. ⋯ But at least during the first two hours the effect is small or else doubtfull. Therefore a combination with bupivacain, a local anesthetic which acts rapidly but only for some hours can be recommended. Most authors testing this combination found it most useful.
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Besides other reasons, cost containments mandate the rational use of preoperative screening tests which should be adapted to the risk of the individual patient. Since the perioperative cardiac risk increases with age, elderly patients in particular require a thorough evaluation of their perioperative risk. Routine ECG, however, is not indicated in patients under 45 years of age who do not present with signs or history of preexisting cardiac diseases but should be performed on a routine basis in all patients over 45 years of age. ⋯ In patients whose perioperative cardiac risk as assessed clinically and by ECG is ambiguous, dipyridamole-thallium-myocardial scintigraphy (DTMS) and dobutamine-stress-echocardiography may contribute valuable information regarding the prediction of perioperative adverse cardiac events. In that respect, dobutamine-stress-echocardiography appears to be superior to DTMS. The laboratory tests required in patients of different ASA-risk groups and according to their age are presented in an overview.
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The benzylisochinoline muscle relaxants have a highly selective affinity to the motor endplate which is associated with an absence of autonomic side effects such as ganglionic and vagus block. The requirement of only low clinical doses also reduces histamine liberation. Muscle relaxants with high neuromuscular blocking potency have a slow onset. ⋯ The duration of mivacurium neuromuscular block may be drastically prolonged in the presence of low or atypical plasmacholinesterase. Both neostigmine and edrophonium are suitable reversal agents. None of the presently available benzylisochinoline muscle relaxants has the potential to completely replace succinylcholine.
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Pain relief should be considered part of a multimodal postoperative approach. Combining patient-controlled pain therapy with other measures i.e. respiratory therapy or early mobilisation improves the outcome after surgery. In many patients adequate postoperative pain relief can be achieved by an optimal use of traditional pain management strategies. ⋯ Dosage of patient-controlled intravenous opioids or epidural drug combinations must be adjusted to the individual needs of the patients. Best results can only be achieved if the patient remains under observation by the pain service. This requires daily or twice daily rounds including an adequate documentation of pain relief, side effects and complications.
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The extent of myocardial damage occurring during acute myocardial infarction is time dependent, and there is abundant evidence from most clinical trials that mortality reduction is greatest in patients treated early with thrombolytic agents, although beneficial effects have been shown with treatment initiated up to 12 h after onset of symptoms. All studies on prehospital thrombolysis have conclusively shown the practicability and safety of patient selection and administration of the thrombolytic agent. The accuracy of diagnosis in the prehospital setting was comparable to trials of in-hospital thrombolysis, e.g., in the Myocardial Infarction Triage and Intervention Project (MITI) 98% of the patients enrolled had subsequent evidence of acute myocardial infarction. ⋯ The results of randomized studies comparing the results of prehospital and in-hospital thrombolysis seem to justify the prehospital institution of thrombolytic therapy, especially in rural areas where transport times to the hospital are long and the expected time gain is largest. The choice of the thrombolytic agent seems to be of minor importance and should follow prehospital practicability (bolus injection) and costs. Aspirin should be given to all prehospital patients with suspected myocardial infarction regardless of thrombolytic therapy.