Clinics in Anaesthesiology最新文献

Ophthalmological surgery is the most common type of surgery performed in geriatric patients. Many of these procedures can be performed on an outpatient basis with local anesthesia. Preparation and management by the anesthesiologist is effective in preventing serious complications. Careful screening is necessary; patients for whom there are contraindications to local anesthesia are given general anesthesia. General anesthesia is required for most long, complicated retinal procedures, even though the patient may be quite ill; diabetes mellitus with all its complications is a particular problem. Some patients requiring eye surgery need to be admitted to the hospital for care and treatment to insure optimal conditions before surgery.

Many elderly patients suffer from misconceptions; they are very anxious about the possibility of losing vision. Careful preparation and judicious use of premedicant drugs are required. Drug interactions must be avoided and necessary cardiac and antihypertensive drugs continued perioperatively. Because geriatric patients are very susceptible to drug effects, careful titration is necessary, with avoidance of drugs with long half-lives.

During surgery, life-threatening complications of retrobulbar blocks may occur. Prompt, effective treatment is mandatory. There must be constant vigilance regarding vagal reflexes and interactions of ophthalmic drugs.

Patients with eye perforations need very smooth general anesthesia with avoidance of coughing or bucking to avoid further extrusion of eye contents. Nondepolarizing muscle relaxants should be chosen with avoidance of succinylcholine. In cases of suspected difficult intubations, the patient's life should not be placed in severe jeopardy to try to save his eye.

Patients with endophthalmitis are emergent; prompt recognition and aggressive therapy are necessary if there is to be a chance of maintaining useful vision.

Consummate skill of the anesthesiologist, knowledge of surgical techniques and special requirements of the surgeon, with special patient preparation are necessary for optimal anesthetic care of elderly ophthalmologic patients.

Body temperature is normally maintained within very narrow limits by the smoothly coordinated functioning of a system consisting of afferent, central and efferent parts. The sometimes extreme physiologic adjustments necessary to accomplish this will occur even at the expense of circulatory integrity. Any or all parts of the thermoregulatory system can be impaired by either drugs or by age. In general, elderly patients are likely to have both decreased heat production and a lessened ability to prevent heat loss. This makes them especially likely to sustain drops in body temperature during anesthesia and operation. Intraoperatively, accidental hypothermia can cause a relative overdose and prolongation of anesthesia as well as other problems. In the recovery period, residual hypothermia is more likely to be dangerous in the elderly patient both because of prolonged time to awakening and mobility, and because the increased oxygen demand caused by shivering may not be supportable by diminished cardiovascular and respiratory function.

The anesthetic management for extra- and intracranial OVD includes a careful preoperative assessment of the neurologic, cardiovascular, respiratory and metabolic systems. Intraoperative management should include monitors that measure the impact of anesthetic drugs on the systemic and cerebral circulations. Ventilation should maintain P_aco₂ at near normal levels. In patients with inadequate collateral circulation methods to provide cerebral protection (bypass shunt, systemic hypertension, barbiturates) should be considered during carotid cross-clamping. Finally postoperative care should include continuation of monitors that measure systemic blood pressure and the adequacy of cerebral perfusion (clinical evaluation, EEG, Doppler ultrasound). Morbidity and mortality are primarily due to myocardial infarction and stroke. The incidence of these complications is, however, influenced by the care and skill of the surgeon, anesthesiologist and nursing personnel.

The patient with liver disease presents the anaesthetist with a medley of deranged physiology. The variations are of sufficient magnitude that a formula to handle all the conceivable problems is not possible. First and foremost, these patients have a very high morbidity and mortality for surgery. Therefore it is wise to obtain as much preoperative information as possible and Table 6 outlines the 'Arizona protocol’ for preoperative evaluation. It provides, in capsule form, guidelines which can be applied to the patient with cirrhosis who is being prepared for major surgery.

The preparation for anaesthesia of outpatient and dental cases follows the same requirements and precautions as for inpatients. In addition, however, the relatively limited time during which the patient is directly under the care of the anaesthetist means that both the type of patient who can be accepted and the surgical procedure that can be undertaken are restricted.