The physiological basis of geriatric general anaesthesia

A review of comorbidities and spinal surgery

As the population ages, greater numbers of elderly patients will be considered for spinal surgery for spinal stenosis and complex primary and revision reconstructions. The age-related medical comorbidities impact not only on the decision to undertake a procedure but also impact the magnitude of the procedure. The surgeon must understand aging and medical comorbidities to facilitate preoperative decision-making and postoperative care. A review of the more common age-related pathophysiologic changes to the cardiovascular, pulmonary, and central nervous systems is undertaken. General recommendations for perioperative treatment are made relative to published series regarding the impact of age and medical comorbidities on short- and long-term outcomes.

Changes in anesthetic sensitivity and glutamate receptors in the aging canine brain

This study investigated whether the aging process in dogs is associated with an increased sensitivity to inhalation anesthesia and whether age-related changes in glutamate receptors are related to the increased sensitivity. The mean minimum alveolar concentration (MAC) of isoflurane was 1.82 +/- .08% for 2-3 year olds and 1.45 +/- .06% for 11 years olds, indicating that there was an increased potency of isoflurane in the older dogs as compared to the young. These older animals also showed a significant decrease in binding of [3H]glutamate and [3H]dizocilpine ([3H]MK801) to N-methyl-D-aspartate (NMDA) receptors in multiple cortical and hippocampal regions. The density of binding to NMDA receptors in the cortex, using a single concentration of ligand, correlated significantly with individual MAC values. These results demonstrate that dogs experience an increase in anesthetic potency with increased age, similar to humans, and that age-related changes in the NMDA receptor may represent one mechanism underlying this increased sensitivity to anesthesia.

Geriatric pain management. The anesthesiologist's perspective

Geriatric patients have a unique physiology that makes their pain management problematic. This article reviews the issue of geriatric pain management from the perspective of the anesthesiologist. It looks at the main causes of geriatric chronic pain and emphasizes the different analgesic modalities available that can provide maximum relief and minimal potential side effects.

Anesthetic considerations in the geriatric patient

As the population ages the incidence of many urologic diseases increases. The elderly patient often is afflicted with many other concomitant diseases in addition to the general deterioration in their overall health status that occurs as a part of the normal aging process. With new advances in technology, many less invasive techniques have become available to treat many of these conditions, thus making many more elderly patients candidates for surgery. In the geriatric population the anesthetic consideration for surgery is as important as the surgical consideration and good communication between the patient, the family, the urologist and the anesthesiologist can make the entire surgical experience a successful one and achieve the desired outcome.

Respiratory dysfunction after uncomplicated cardiopulmonary bypass

Respiratory dysfunction is a well-recognized complication of cardiac operations. To quantify its current incidence and severity after uncomplicated cardiopulmonary bypass, serial measurements of arterial oxygen tension (PaO2), alveolar-arterial oxygen gradient (AaO2), and percentage pulmonary shunt fraction (%PSF) measured by a noninvasive technique were made in 129 patients (age, 59 +/- 8 years (mean +/- standard deviation) with good left ventricular function (left ventricular end-diastolic pressure < 15 mm Hg) undergoing isolated coronary artery operations (group 1) and 30 patients undergoing general surgical procedures (group 2). Measurements were made before operation and on the first, second, and sixth postoperative days. Seven patients in group 1 who required prolonged ventilation were excluded from further study. In group 1, between the preoperative and second postoperative days, there was a marked fall in PaO2 [89 +/- 11 versus 57 +/- 9 mm Hg; p < 0.001] and a marked increase in the AaO2 gradient [18 +/- 10 versus 50 +/- 11 mm Hg; p < 0.001)] and %PSF [3 +/- 1% versus 19 +/- 6%; p < 0.001)] with only modest improvement by the sixth postoperative day [PaO2, 67 +/- 11 mm Hg; AaO2, 45 +/- 11 mm Hg; %PSF, 15 +/- 4]. There were similar but less severe changes in PaO2 and AaO2 gradients in group 2 patients, with a return to baseline values by day 6.(ABSTRACT TRUNCATED AT 250 WORDS)

Impact of aging on preoperative evaluation

Approximately 40% of physician office time and 33% of hospital time are devoted to patients 65 years of age or older. Over half of the older population requires some surgical intervention. Because of decreased physiologic reserve and increased number of underlying medical disorders, the older patient is at increased risk for intraoperative and postsurgical complications. Since cardiovascular, pulmonary, and renal complications are frequent in the elderly patient, the preoperative evaluation should emphasize these organ systems. Risk factors should be assessed initially by a focused history and physical examination and by simple tests. Additional diagnostic testing should be reserved for the patient who is not clearly at low or high risk. For optimal preoperative evaluation of the elderly patient, the physician should identify systemic disease, determine if the patient is receiving appropriate therapy, delineate the operative risks, and make recommendations that can potentially reduce the operative risks and postoperative complications.

Hemodynamic and metabolic effects of ketamine anesthesia in the geriatric patient

The cardiovascular and metabolic effects of ketamine as the sole anesthetic agent for surgical correction of fractured neck of femur were studied in eight spontaneously breathing geriatric patients (mean age 83 years) before premedication, at the end of operation, and 15 min and 2 h after the end of anesthesia. Arterial blood pressure, cardiac index, left ventricular stroke work index and oxygen consumption increased during anesthesia but had returned to preoperative levels 15 min after the end of anesthesia. Vascular resistance, heart rate and stroke volume index were not significantly changed. During anesthesia, arterial carbon dioxide tension increased whereas arterial pH and arterial BE decreased. The levels of glucose and lactate increased in both blood and skeletal muscle during anesthesia and remained elevated throughout the period studied but the lactate:pyruvate ratio was unchanged. High energy phosphagen levels in skeletal muscle did not change. Ketamine anesthesia in the spontaneously breathing geriatric patient induces cardiovascular stimulation and metabolic changes indicative of an increased sympathetic stimulation, whereas respiration is slightly depressed. The magnitude of these changes is, however, small and it thus seems that ketamine can be safely used as the sole anesthetic agent for hip fracture surgery in the average geriatric patient.