Inhalation anaesthesia at the extremes of age: geriatric anaesthesia

Three versus five lumbar paravertebral injections for inguinal hernia repair in the elderly: a randomized double-blind clinical trial

PURPOSE

The objective of the study was to compare three nerve stimulator-guided paravertebral injections versus five injections for elderly patients undergoing inguinal hernia repair in terms of the amount of intraoperative fentanyl and propofol consumption and conversion to general anesthesia. The secondary objective was postoperative pain.

METHODS

A prospective, randomized, double-blind clinical trial was performed. 200 elderly patients undergoing unilateral herniorrhaphy were randomized into two groups. Group III received three PVB injections from T₁₂ to L₂ and placebo at T₁₁ and L₃. Group V received five PVB injections from T₁₁ to L₃.

RESULTS

The mean intraoperative fentanyl and propofol consumption were significantly lower in group V (4.9 ± 7.2 µg versus 20.0 ± 12.9 µg and 5.7 ± 11.6 mg versus 34.6 ± 22.9 mg, respectively, p value < 0.0001). Five patients (5.0%) in group III had failed block and were converted to general anesthesia (p value = 0.024). Group V had significantly lower pain scores compared to group III during the first three postoperative days (p value < 0.0001).

CONCLUSION

The five PVB injection technique is more suitable as a sole anesthetic technique for elderly patients undergoing herniorrhaphy, since it required less intraoperative supplemental analgesia and provided lower postoperative pain scores compared to the three PVB injection technique.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02537860.

Unique Aspects of the Elderly Surgical Population: An Anesthesiologist's Perspective

Increasing life expectancies paired with age-related comorbidities have resulted in the continued growth of the elderly surgical population. In this group, age-associated changes and decreased physiological reserve impede the body's ability to maintain homeostasis during times of physiological stress, with a subsequent decrease in physiological reserve. This can lead to age-related physiological and cognitive dysfunction resulting in perioperative complications. Changes in the cardiovascular, pulmonary, nervous, hepatorenal, endocrine, skin, and soft tissue systems are discussed as they are connected to the perioperative experience. Alterations affect both the pharmacodynamics and pharmacokinetics of administered drugs. Elderly patients with coexisting diseases are at a greater risk for polypharmacy that can further complicate anesthetic management. Consequently, the importance of conducting a focused preoperative evaluation and identifying potential risk factors is strongly emphasized. Efforts to maintain intraoperative normothermia have been shown to be of great importance. Procedures to maintain stable body temperature throughout the perioperative period are presented. The choice of anesthetic technique, in regard to a regional versus general anesthetic approach, is debated widely in the literature. The type of anesthesia to be administered should be assessed on a case-by-case basis, with special consideration given to the health status of the patient, the type of operation being conducted, and the expertise of the anesthesiologist. Specifically addressed in this article are age-related cognitive issues such as postoperative cognitive dysfunction and postoperative delirium. Strategies are suggested for avoiding these pitfalls.

Anaesthesia and the elderly

As a result of age-related physiological changes and multi-comorbidity, which both result in reduced functional reserve of the organ systems, old patients are more vulnerable to surgical stress and perioperative impairment in organ functions. Therefore, the incidence of severe complications during the perioperative course is increased in the elderly. Regional anaesthesia or a combination of regional and general anaesthesia is considered to be beneficial in elderly patients, because neuraxial blockade may reduce sympathetic activation, and has been demonstrated to reduce postoperative mortality. Other protective strategies to maintain organ functions in elderly patients include medication with beta-blockers in patients with cardiovascular risks, the avoidance of hypothermia, the maintenance of systemic oxygen delivery, and patient-controlled pain therapy.

A Comparison of Target- and Manually Controlled Infusion Propofol and Etomidate/Desflurane Anesthesia in Elderly Patients Undergoing Hip Fracture Surgery

Elderly patients have a higher risk of developing adverse drug reactions during anesthesia, especially anesthesia affecting cardiovascular performance. In this prospective randomized study we compared quality of induction, hemodynamics, and recovery in elderly patients scheduled for hip fracture surgery and receiving either etomidate/desflurane (ETO/DES) or target-controlled (TCI) or manually controlled (MAN) propofol infusion for anesthesia. Sixteen patients were anesthetized with ETO (0.4 mg/kg) followed by DES titrated from an initial end-tidal concentration of 2.5%. Eighteen patients received propofol TCI at an initial plasma concentration of 1 microg/mL and titrated upwards by 0.5-microg/mL steps. Fifteen patients received a bolus induction of propofol 1 mg/kg over 60 s followed by an infusion initially set at 5 mg . kg(-1) . h(-1). All received a bolus (20 microg/kg) followed by an infusion of 0.4 microg . kg(-1) . min(-1) alfentanil. According to hemodynamics, concentrations of DES or propofol (TCI group) and propofol infusion rate (MAN group) were respectively adjusted by a step of 20% and 50%. In the TCI and ETO/DES groups, the time spent at a mean arterial blood pressure within 15% and 30% of baseline values was more than 60% and 80% of anesthesia time, whereas in the MAN group it was <30% and 60%, respectively. In the MAN group more anesthetic drug adjustments were recorded (6.4 +/- 2.8 versus 2.5 +/- 1.2 [ETO/DES] and 2.6 +/- 1 [TCI]). TCI improves the time course of propofol's hemodynamic effects in elderly patients.

Pharmacokinetics in the elderly

The elderly are an expanding population of patients presenting for anaesthesia. The pharmacokinetics of anaesthetic agents in the elderly deserves special attention because the normal ageing process and the effect of age-related diseases affect organ systems in a heterogeneous way with unpredictable consequences. The pharmacokinetics of each drug is also affected by these changes in a specific way and, together with the pharmacodynamic consequences, makes drug use and drug dosing challenging in this population. Although a decrease in bolus and infusion rates is a common theme, only pharmacokinetic modelling of drug disposition in the elderly will provide accurate dosing guidelines and increase the margin of safety.

Anesthetic considerations of the older equine

This article briefly reviews physiologic changes that may occur with aging in equine patients. It summarizes anesthetic protocols and problems encountered in a group of older horses (> 20 years old) anesthetized over the previous 10 years in the teaching hospital and makes recommendations for appropriate management of these patients.

Effect of age on haemodynamic response to tracheal intubation. A comparison of young, middle-aged and elderly patients

The effect of age on the haemodynamic response to tracheal intubation was studied. Ninety ASA 1 or 2 patients were divided into three groups of 30 each based on age; ie., young (18-25 years), middle-aged (40-50 years) and elderly (65-80 years). The haemodynamic response after tracheal intubation was observed as percentage change in heart rate and blood pressure compared to the baseline. Inter-group comparison was also done at different time points. The greatest percentage change in the systolic arterial pressure after tracheal tube insertion was seen in the elderly group (15%). The increase in systolic arterial pressure was significantly less in theyounggroup compared with the two older groups at one, two, three and four minutes post-intubation. The greatest percentage increase in the diastolic blood pressure compared to the baseline was seen in the middle aged group (24%). The elderly and young patients showed a significant difference in the diastolic blood pressure response only at one minute post-intubation. The heart rate response was greatest in the middle-aged patients (40%) and least in the elderly (16%). These differences may have clinical significance and should be considered in assessing and performing research into the haemodynamic response to intubation.

Low-flow desflurane and sevoflurane anesthesia minimally affect hepatic integrity and function in elderly patients

Hepatic blood flow is reduced in a dose-related manner by all inhaled anesthetics now in use. We assessed hepatic function in elderly patients anesthetized with desflurane or sevoflurane. We measured the cytosolic liver enzyme alpha glutathione S-transferase (alpha GST), the formation of the lidocaine metabolite monoethylglycinexylidide (MEGX), and gastric mucosal tonometry-derived variables as sensitive markers of hepatic function and splanchnic perfusion. Thirty patients, 70 to 90 yr old, were allocated randomly to receive desflurane or sevoflurane anesthesia. Anesthetic exposure ranged from 2.1-4.5 minimum alveolar concentration hours. No significant changes in standard liver enzyme markers were seen throughout the study. In both anesthetic groups, tonometric measurements showed a significant decrease from baseline in regional PCO(2), regional to arterial difference in PCO(2), and intramucosal pH at 90 min after skin incision. alpha GST concentrations increased significantly in both groups (desflurane: median peak concentrations 5.8 microg/L [25th, 75th percentile 5.3 microg/L, 7.2 microg/L]; sevoflurane: 7.0 microg/L [5.8 microg/L, 7.3 microg/L]) without showing differences between both anesthetic groups. A return to baseline values in tonometric values and alpha GST levels was seen 24 h postoperatively. MEGX formation did not change significantly after surgery. Median MEGX concentrations postoperatively were 70.0 ng/mL (56.2 ng/mL, 102.0 ng/mL) and 70.0 ng/mL (60.0 ng/mL, 94.2 ng/mL) in the desflurane and sevoflurane groups, respectively. We conclude that, overall, liver function in elderly patients is well preserved during desflurane and sevoflurane anesthesia. Increased serum levels of alpha GST and changes of gastric tonometry-derived variables imply a reduction in splanchnic perfusion, leading to a temporary impairment of hepatocyte oxygenation.

IMPLICATIONS

We measured the lidocaine metabolite monoethylglycinexylidide, the cytosolic liver enzyme, alpha glutathione S-transferase, and gastric mucosal tonometry-derived variables to evaluate the effects of desflurane and sevoflurane on hepatic function in elderly patients. Liver function was well preserved, whereas increased alpha glutathione S-transferase levels and changes in tonometry-derived variables indicated a reduction in splanchnic blood flow and a temporary impairment of hepatocyte oxygenation for both anesthetics.

Desflurane and sevoflurane. New volatile anesthetic agents

Desflurane and sevoflurane, recently licensed for use in humans, have kinetics that result in rapid induction and easy maintenance of a stable level of anesthesia. Recovery is also rapid. Cardiopulmonary effects are similar to those of isoflurane. In humans, desflurane can cause airway irritation and sympathetic stimulation, but these side effects have not caused problems in animal trials. Metabolites of sevoflurane and breakdown products from its reaction with carbon dioxide absorbents theoretically could result in hepatic and renal damage, but such toxicity has not occurred despite extensive medical use. Clinical trials in animals are now in progress.

Assessment of cardiovascular risks and overall risks for noncardiac surgery

Appropriate care of the elderly patient requires a concerted multi-disciplinary approach before, during, and after surgery to optimize functional outcomes, with the principal focus placed on improving quality of life and strategies for risk reduction. Perioperative physicians must be able to assess the biologic, not the chronologic, age of geriatric patients and their capacity for independent function. Physicians need to understand alterations in the physiology of elderly patients attributable to the normal aging process as well as the prevalence of concurrent pathologic conditions that necessitate special precautions. Maintaining autonomy and function as a result of an acute surgical intervention may be the most important outcome to the elderly patient. Most of the data available and guidelines promulgated do not specifically address the elderly population. It is important to collect data prospectively and use sophisticated methods for analyses to develop better management algorithms for these (often complicated) clinical issues in the elderly.

The induction, maintenance, and recovery characteristics of spinal versus general anesthesia in elderly patients

STUDY OBJECTIVE

To compare the induction and recovery profiles of three combinations of general anesthesia when used as an alternative to spinal anesthesia for elderly patients.

DESIGN

Randomized, prospective, open-label study.

SETTING

Large referral hospital.

PATIENTS

100 [ASA physical status I, II, and III] patients over 60 years of age undergoing brief transurethral surgery.

INTERVENTIONS

In Groups Propofol-Propofol (P-P), Propofol-Isoflurane (P-I), and Propofol-Desflurane (P-D), anesthesia was induced with fentanyl (1 to 2 micrograms/kg i.v.) and propofol (1.0 to 2.0 mg/kg i.v.) and maintained with 70% nitrous oxide in oxygen and either a propofol infusion (75 to 150 micrograms/kg/min) or isoflurane (end-tidal 0.7% to 1.2%) or desflurane (end-tidal 1% to 4%), respectively. After induction, a laryngeal mask airway was placed and spontaneous ventilation was maintained. In Group Spinal (S), 1.5 ml 4% lidocaine (60 mg), in an equal volume of 10% dextrose, was administered intrathecally.

MEASUREMENTS AND MAIN RESULTS

Induction and recovery characteristics were compared. Induction with propofol was technically easier and significantly (medp < 0.0001) faster (4.6 +/- 1.7 min, 4.7 +/- 2.2 min, and 3.8 +/- 1.4 min for Groups P-P, P-I, and P-D, respectively) than induction of spinal anesthesia (9.3 +/- 3.4 min). During the induction period, mean arterial blood pressure and heart rate were significantly higher in Group S. Emergence, extubation, and orientation times were similar among the general anesthesia treatment groups. In Group S, patient-generated pain scores were lower (p < 0.05) and recovery room admission longer (p < 0.001). Time to return to baseline digit symbol substitution test (DSST) scores was marginally improved in Groups P-P and P-D when compared to Group P-I. Postoperative nausea, sleepiness, anxiety, and coordination were unaffected by the treatment modality.

CONCLUSION

General anesthesia with propofol and desflurane facilitates shorter induction and recovery times without adversely affecting patient comfort. Therefore, this technique may be preferable to spinal anesthesia for elderly patients undergoing short transurethral surgical procedures.