Frailty in anesthesia

Abstract

Purpose of review

Due to demographic change, the number of geriatric patients is increasing in the surgical field. This poses a major challenge in perioperative medicine. In order to improve patient safety, frailty has become a key element for risk assessment in the perioperative setting. This review aims to summarize the current state of anesthesia in frail patients.

Recent findings

Frailty is an independent risk factor for intraoperative and postoperative complications, mortality, and length of hospital stay. The Clinical Frailty Scale has been shown to be a feasible, easy-to-use tool for frailty assessment. Frailty is likely to be modified through targeted preoperative optimization (prehabilitation). This should be carried out on a multidisciplinary basis. During preoperative risk assessment, special attention should be paid to polypharmacy and multimorbidity. Particularly in geriatric patients, maintaining intra- and postoperative homeostasis is essential. Adequate pain management and prevention of perioperative delirium are of utmost importance.

Summary

Frailty is a common and highly relevant clinical risk factor in the perioperative setting. In future, efforts should focus on identifying methods to improve the status of preoperative frail patients.

KEY POINTS.

• Frailty is an independent risk factor for intraoperative and postoperative complications, mortality, and length of hospital stay.

• The risk factor of frailty is likely to be modified through targeted preoperative optimization (prehabilitation). This should be carried out on a multidisciplinary basis. During preoperative risk assessment, special attention should be paid to polypharmacy and multimorbidity. The Clinical Frailty Scale is a feasible, easy-to-use tool for assessing frailty.

• Particularly in geriatric patients, maintaining intra- and postoperative homeostasis is essential.

• Adequate pain management and prevention of perioperative delirium are of utmost importance.

INTRODUCTION

Due to demographic change, the proportion of older and multimorbid patients undergoing surgical procedures is increasing [1,2]. In this context, a multicentre study by the POSE Study Group showed that patients over 80 years of age undergoing any kind of surgical or nonsurgical procedures under anesthesia revealed an estimated 30-day mortality rate of 4.2% [3]. In order to improve patient’s safety, frailty has become a key element in assessing risk before, during and after surgery. The term frailty thereby describes a multidimensional syndrome characterized by reduced physiological reserve, functional decline, and increased vulnerability to stressors such as surgery and anesthesia [4–6]. It is distinct from chronological age and individual comorbidities. Frailty reflects an individual’s actual resilience and biological age. Furthermore, it is a strong independent predictor of postoperative complications, prolonged hospitalization, further functional decline and postoperative mortality [7]. Zhang et al. demonstrated in a recent meta-analysis that the odds ratio for 30-day mortality is approximately three to five times higher in frail patients compared to nonfrail patients, in both elective and emergency surgical settings [8^■]. Higher frailty scores (regardless of the instrument used) are associated with a higher risk of mortality [9,10]. The perioperative decision-making process should therefore incorporate frailty as a risk factor, in line with international guidelines. Based on this, interdisciplinary, geriatric-oriented treatment pathways should be implemented to improve patient outcomes [11^■■,12^■].

FRAILTY SCORES AND PERIOPERATIVE RISK ASSESSMENT

Determining frailty status is an important factor in individualized risk assessment in geriatric patients [13]. Various instruments are available for the structured assessment of frailty. A classic approach is the phenotypic frailty score according to Fried, which comprises five criteria: unintentional weight loss, exhaustion, reduced grip strength, slow walking speed, and low activity level [14]. The presence of three or more criteria defines manifest frailty, while one to two criteria are considered prefrailty. This model is well validated, but time-consuming in everyday perioperative practice.

An alternative approach is the deficit accumulation approach according to Rockwood. The Clinical Frailty Scale (CFS) [15] has proven to be a pragmatic instrument for routine clinical use (Fig. 1). The CFS is a nine-point scale ranging from ‘very fit’ (level 1) to ‘terminally ill’ (level 9) and is based on a global clinical impression. It takes into account mobility, everyday functioning, need for assistance, and energy level [15]. Numerous studies have shown that frailty is associated with a significantly increased risk of postoperative complications, delirium, prolonged hospital stays, and mortality [5, 8^■,17,18]. There is currently no generally accepted gold standard for assessing frailty, which makes it difficult to compare studies in this area. In an analysis of the most common frailty scores, Aucoin et al. showed that the CFS has the greatest clinical practicality [19]. The European Society of Anesthesiology and Intensive Care (ESAIC) also recommends the CFS for frailty screening in its updated guideline for the preoperative assessment of adults undergoing elective noncardiac surgery [11^■■]. An exemplary overview of the various screening instruments is summarized in Table 1.

FIGURE 1.

Clinical Frailty Scale. Modified from Geriatric Medicine Research, Dalhousie University Halifax, and Rockwood et al. [16].

Table 1.

Instruments for assessing the degree of frailty (modified according to Mende et al. [2])

Frailty definition/measuring instrument	Categories	Comments
Phenotype according to Fried [14]	5 criteria: unintentional weight loss, exhaustion, muscle weakness, walking speed, physical activity.	Main focus is on physical characteristics.
CSHA Frailty Index (CSHA-FI) [15]	70 variables: physical function, cognitive status, mental illness, everyday functionality.	High time expenditure.
Clinical Frailty Scale (CFS) [16]	Subjective assessment by the examiner; 9-point scale.	Low time expenditure.
Modified Frailty Index (mFI) [20]	11 criteria, based on CSHA; focus on heart/lung/ cerebrovascular diseases.	Established in thoracic surgery patients.
Edmonton Frail Scale [21]	10 criteria: cognitive status (clock test), general health, quality of life, functional independence, social support, medication history, nutrition, mood, continence, mobility test.
LUCAS-function index [22]	Self-administered questionnaire consisting of 12 marker questions regarding resources and risks, classification into ‘fit’, ‘prefrail’, or ‘frail’.
Manageable Geriatric Assessment (MAGIC) [23]	Nine criteria: everyday functioning, vision, hearing, falls, urinary incontinence, depression, social environment, vaccination protection, orientation test for cognitive performance (clock test).	Two signal questions before the assessment; if there are indications of abnormalities, MAGIC is appended. Additional optional content: chronic pain, dizziness, mobility and flexibility, unwanted weight loss, medication review.

CSHA, Canada Study of Health and Aging; LUCAS, Longitudinal Urban Cohort Aging Study.

In multivariate models, frailty often remains an independent predictor of mortality and serious complications, even after adjusting for age, ASA status, and comorbidities [5,7]. This is particularly significant given that currently 4–17% of the population over the age of 65 is considered frail [24] and that the prevalence of frail patients in the perioperative setting is approximately four times higher than in the general population [25]. Varley et al. were able to show that simply recording frailty preoperatively and adding an automatic alert to the electronic patient record has the potential to reduce one-year mortality in frail patients by 20% [26].

PREHABILITATION

Given the increased vulnerability of frail patients, the concept of prehabilitation has gained importance [27] and is also promoted as the ‘better-in-better-out’ concept [28]. The aim is to improve functional reserve prior to surgery in order to better compensate for the stress of, for example, surgical trauma and anesthesia. To achieve this goal, prehabilitation usually involves physical training, nutritional support, respiratory muscle training, and psychological counseling.

Data on the usefulness of uni- or multimodal prehabilitation programs on patient outcomes are contradicting. Some randomized studies showed that multimodal prehabilitation programs significantly increased functional capacity, measured for example by the 6-minute walk test or maximum oxygen uptake, and that they are associated with a lower rate of postoperative complications [29,30]. Frail or sarcopenic patients in particular benefitted significantly from preoperative structured training and nutrition programs [31^■,32^■]. Contrary, one recently performed meta-analysis reported only beneficial outcomes for the specific group of lung cancer patients with the use of unimodal exercise interventions [33]. Moreover, some national oncological guidelines [34] do not recommend resource-consuming prehabilitation programs, as the level of evidence for less complication rates and better postoperative outcomes is very low to low. Reasons are high heterogeneity of treatments, the time-points of prehabilitation tasks and psychosocial support among the studies. Also, distinction between effects of routinely performed measures within enhanced recovery after surgery programs in control groups and specific prehabilitation tasks is difficult. Thus, prehabilitation tasks may be performed, but only less resource-consuming standard measures such as abstaining from alcohol and smoking and written instructions for physical exercises at their own at home are recommended [34].

Accordingly, another important point is the nutritional optimization. Malnutrition and sarcopenia are considered important predictors of poor outcomes and should be consistently addressed preoperatively [35]. The European Society for Clinical Nutrition and Metabolism guidelines emphasize the importance of early identification of malnutrition and the implementation of structured nutritional therapy as an integral part of preoperative care. This should include a dietary measures optimized for protein and energy, complemented with medical nutritional therapy or other supplements if necessary [35]. The ESAIC also gives a moderate recommendation for preoperative nutritional optimization (2C: ‘Nutritional support before surgery should be considered’) [11^■■].

PREOPERATIVE EVALUATION

Older patients particularly require careful preparation before surgery due to their age and the associated physical changes [11^■■]. A transparent preoperative consultation, ideally attended by relatives, is especially important. The preoperative evaluation of frail patients must also go beyond classic risk stratification. In addition to medical history, physical examination and standard diagnostics, structured frailty screening should be established, preferably using the CFS or comparable validated instruments [7,11^■■]. In addition, it is recommended to collect functional parameters such as walking speed and assessment of everyday competence [36].

The main goals of the preoperative assessment are to identify reversible risk factors and polypharmacy, as well as to optimize comorbidities and discuss risks within the framework of shared decision making. Typical optimization measures include the treatment of preoperative anemia, the adjustment of heart failure therapy, the stabilization of obstructive respiratory diseases, and a critical review of medication with a reduction of potentially delirogenic substances [37]. Prehabilitation should be multidisciplinary and, in particular, strengthen the patient’s competence (‘empowerment’) so that patients themselves can actively contribute to improving their health status and postoperative recovery [38].

Postoperative delirium (POD) is one of the key challenges in the perioperative setting, as it is often associated with unfavorable clinical outcomes and prolonged hospital stays [39]. In particular, patients aged over 85 are up to six times more likely to develop POD [40]. However, preoperative strategies and nonpharmacological interventions can significantly reduce the risk. It is specifically important to avoid substances with anticholinergic effects. It should also be ensured that patients spend as little time as possible without essential aids such as glasses, hearing aids, or dentures [41^■■].

For a long time, benzodiazepines were seen very critically with regard to postoperative delirium [42]. However, chronic benzodiazepine intake or continuous administration on ICU have to be distinguished from a single low dose premedication immediately administered before surgery [43–45]. Recently, the debate about the use of benzodiazepines in pharmacologic premedication has gained momentum again, as several studies have relativized the previously assumed negative effects of this class of drugs. For example, studies by Wang et al. and Li et al. show that intravenous administration of 2 mg midazolam was not associated with an increased rate of POD [46^■,47]. Similarly, in a study by Kowark et al., the administration of 3.75 mg midazolam per os had no significant impact on patient satisfaction [48^■]. Surprisingly, a benzodiazepine premedication in patients of the POSE study was even associated with a significantly lower 30-day mortality rate (3.21% vs. 4.45%) [49]

Preoperative anxiety is an important ubiquitously existent issue, associated with several complications, and increased risk of postoperative adverse outcomes [50]. Thus, measures should be implemented to recognize patients with increased anxiety and a preoperative treatment with low dose benzodiazepines, such as titration of 1–2 mg intravenously should be considered for these patients.

An unnecessarily long fasting period is problematic especially for older patients, as it substantially can affect their physiological homeostasis. Therefore, fasting periods should be kept as short as possible (2 h for clear liquids, 6 h for solid food), as particularly older patients have limited ability to compensate for intraoperative fluid and blood loss. In practice, however, patients often remain fasting for much longer than necessary, which should urgently be avoided [51]. Therefore, several hospitals have introduced a more liberal policy on drinking before surgery, encouraging patients to drink small amounts of water till they are transferred to the operating room (‘sip til send’) [52^■].

The indication for major surgery should be critically examined, especially in patients with a high degree of frailty (e.g. CFS ≥ 5). Open, structured risk disclosure enables patients to weigh up the risks and expected benefits of a procedure together with their treating physician. Frailty scores therefore serve not only to describe risks, but also as a basis for ethically informed treatment decisions.

INTRAOPERATIVE MANAGEMENT

Careful planning and monitoring are essential for the intraoperative management of frail patients. Reduced cardiovascular and respiratory reserve make patients more susceptible to hypotension, hypoxia and organ hypoperfusion.

Several studies have shown that intraoperative hypotension is associated with postoperative myocardial damage, renal dysfunction, and increased mortality [53,54]. Intraoperative hypotension with mean arterial pressures less than 60–70 mmHg or systolic arterial pressures <90–100 mmHg and high norepinephrine doses should be avoided in patients undergoing noncardiac surgery [54,55].

Experts broadly agree that maintaining the physiological balance (homeostasis) of older patients significantly improves perioperative outcomes. Careful temperature management is particularly important, as disturbances in thermal regulation can promote postoperative complications and prolong the length of stay in hospital. The prevention of postoperative shivering is also of key importance: the associated significant increase in oxygen demand – sometimes by up to 40% – can pose a considerable risk for people with preexisting cardiac conditions [56].

The choice of anesthesia procedure should specifically meet the patient’s demands and be appropriate for the procedure. Even though there are no specific guidelines for the intraoperative monitoring of geriatric patients, close hemodynamic assessment should be carried out when indicated, including invasive blood pressure measurement for major procedures, individualized volume therapy, and consistent avoidance of prolonged hypotension. Regional anesthesia techniques can offer advantages in terms of analgesia, opioid reduction, and delirium prevention in suitable patients, but might not be suitable in all clinical situations. The increasing number of older people with hip fractures is a significant global health burden [57]. Data on the preferable anesthesia technique for this patient population is heterogeneous. A Cochrane review demonstrated no difference between the use of neuraxial vs. general anesthesia on the 30-day mortality or morbidity of patients undergoing hip fracture surgery [58]. In the meta-analysis by van Waesberghe et al., which comprised large cohort studies, regional anesthesia was found to be advantageous in terms of hospital mortality, length of stay, and cardiovascular and respiratory complications, but not in terms of 30-day mortality [59]. Contrary, recent large randomized studies such as REGAIN and RAGA were unable to demonstrate any clinically relevant advantage of either procedure in terms of mortality or POD rates [60,61]. Li et al. also found no variation in the incidence of POD depending on the anesthesia technique used [60]. Similarly, neither Fan et al. nor Vail et al. could demonstrate significant differences in terms of major complications [62,63^■]. The still ongoing joint evaluation of the multicenter iHOPE study [64] with data from the REGAIN study is expected to provide a more precise basis for recommendations on the choice of anesthesia procedure in geriatric patients in the future.

In principle, all common regional anesthesia procedures can be considered for older patients, provided there are no contraindications. For hip fractures, for example, the American Academy of Orthopedic Surgeons recommends the femoral nerve block and the iliac fascia block, among others, as effective analgesic procedures [65]. The American Society of Anesthesiologists Practice guideline recommends the use of fascial plane blocks for open cardiothoracic, abdominal, retroperitoneal, and pelvic surgeries and mastectomy [66]. The routine use of ultrasound provides reliable methods for peripheral nerve blocks, which can be a useful supplement to general anesthesia – especially in the context of perioperative pain management. The German S3 guideline for the treatment of acute perioperative and posttraumatic pain also advocates these techniques as well as the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care [67,68]. In addition to higher patient satisfaction, another advantage is the reduced need for postoperative analgesics, including opioids.

Frail patients exhibit increased sensitivity to anesthetics and sedatives. Therefore, monitoring the depth of anesthesia should be considered in older people. Excessively deep anesthesia should be avoided, as this has been linked to an increased risk of POD and long-term cognitive impairment. Careful titration of hypnotics and opioids and the use of multimodal, opioid-sparing analgesia concepts are therefore particularly important [69]. Previous studies and meta-analyses have described a correlation between deep anesthesia particularly at burst-suppression levels, assessed, for example, by electroencephalogram (EEG) or bispectral index monitoring, and an increased rate of delirium and cognitive dysfunction [70,71]. However, the actual benefits of EEG-based monitoring in this context are currently being increasingly critically discussed. More recent studies have not been able to show any clear advantage for patients who were anesthetized under EEG guidance [72]. Accordingly, in its updated guideline ‘Evidence-based and consensus-based guideline on postoperative delirium in adult patients’, the ESAIC now only recommends depth of anesthesia control using EEG with a ‘weak’ recommendation [41^■■].

POSTOPERATIVE MANAGEMENT AND DELIRIUM PREVENTION

POD is a serious and common complication that can occur after surgery, especially in older and frail patients. Incidences are depending on the analyzed patient population and type of surgery, with highest incidences up to 65% reported for patients undergoing hip fracture surgery [73]. It is associated with an increased length of hospital stay, long-term cognitive decline, functional impairment and an increased risk of death [7]. The postoperative phase is critical for frail patients, as surgery and anesthesia further reduce their physiological reserves. Cardiorespiratory instability, infections, functional decline, and delirium are common. Therefore, structured, interdisciplinary postoperative care is essential for decreasing morbidity and mortality [5,74].

In this context, adequate pain management and measures to prevent POD in older patients are of the utmost importance. The ESAIC recommendations for delirium prevention [41^■■] and the national S3 guideline for Analgesia, Sedation, and Delirium Management in Intensive Care Medicine [43] both indicate that consistent, age-appropriate analgesia is essential for decreasing the risk of POD.

Other key elements include early contact to close relatives or caregivers, close monitoring (if necessary, in an intermediate or ICU), early and regular mobilization, and consistent respiratory therapy. Structured nutritional management with early oral or enteral feeding is also important to prevent further muscle loss and functional decline [35].

Therefore, international guidelines primarily recommend nonpharmacological prevention strategies such as reorientation, sleep hygiene, adequate lighting, use of glasses and hearing aids, early mobilization, and optimized fluid and nutritional care [41^■■]. Many patients also benefit from having trusted relatives or other caregivers involved in their postoperative care at an early stage. Screening for postoperative cognitive disorders and delirium should also be continued consistently after surgery [41^■■]. Routine pharmacological prophylaxis with antipsychotics is not recommended, however, as the evidence does not show any clear benefit and relevant side effects may occur [75]. It is much more important to specifically avoid or reduce medication with the potential to induce delirium and to focus treatment on addressing the causes and providing supportive measures [37].

Care for older patients should be provided by an interdisciplinary team that ensures adequate nutrition, early mobilization, and effective multimodal and opioid-sparing pain management [76]. It is equally important to begin rehabilitative measures in specialized facilities as soon as possible. Studies show that continued treatment in specialized geriatric wards can improve both survival rates and quality of life after returning home [77,78].

CONCLUSION

Frailty is a common and highly relevant clinical risk factor in the perioperative setting. A standardized assessment of frailty should be an integral part of the preoperative evaluation of elderly patients. Perioperative risks can be reduced through prehabilitation based on the ‘better in, better out’ principle. Preventing delirium, managing pain adequately, and maintaining homeostasis consistently are also crucial. A structured, interdisciplinary and guideline-oriented approach is essential to sustainably improve the postoperative outcome of this vulnerable patient group.

Acknowledgements

None.

Financial support and sponsorship

None.

Conflict of interest

A.K. is at the advisory board of Paion Pharma and has received speaker’s fees from Paion Pharma. M.C. received speaker’s fees from Fresenius Kabi Deutschland GmbH and Dräger Medical Deutschland GmbH. M.C. is Chair of the Research Committee, European Society of Anesthesiology and Intensive Care and Chair of the Sustainability Committee, German Society of Anesthesiology and Intensive Care Medicine. For the remaining authors, there are no conflicts of interest.