Although there are more than 50 instruments used to assess frailty [34], there are only two definitions that are widely used: the Deficit Accumulation Model from Rockwook and Mitnitski, which takes factors from multiple domains into consideration, and the Frailty Phenotype Model from Fried, which is primarily based on aspects of physical decline.

The Deficit Accumulation Model [35, 36] represents a multidimensional risk assessment, which analyzes patient history for deficits accumulated across several domains. The model incorporates 30–70 aspects, including physical condition, comorbidities (such as stroke, diabetes, and cardiorespiratory conditions), as well as activities of daily life (ADL), to calculate a numerical index on a 7-point Clinical Frailty Scale.

In comparison, the Phenotype Model [13] defines frailty as a clinical syndrome, whereas it is noted whether the following characteristics are present: unintentional weight loss, self-reported exhaustion, weakness, slow gait speed, and low physical activity (see Table 19.1). The patient is deemed to be frail if three or more of these traits are present, and pre-frail if only one or two traits are observed. If none of the criteria is present, the patient is deemed to be non-frail.

Although there is no consensus on which components should be included in the frailty assessment and none of the instruments can be considered a gold standard [37], the physical phenotype model from Fried has been the most frequently used definition [34]. In addition to the physical dimension of the Frailty Phenotype, additional instruments can be used to account for cognitive and social aspects.

Clinical management of frail elderly patients requires multidisciplinary cooperation between anesthesiologists, surgeons, intensivist, geriatrists, nurses, pharmacologists, physiotherapists, and nutritional assistants. The assessment of domains can be conducted using clinical tests (see Table 19.2) or questionnaires. In the absence of consensus, the instruments used must be critically selected based on the type of treatment and interventional capabilities. In case of emergency, per instance, when there is no time for a comprehensive geriatric assessment, surrogate markers should be employed.

The following describes some of the most commonly used instruments in the assessment of frailty:

Unintentional weight loss/body mass index (BMI): the unintentional weight loss of more than 4.5 kg in the previous year, or a low BMI, can be a marker for malnutrition, sarcopenia, or incipient cachexia [13].

Exhaustion: self-reported lack of energy or fatigue. This may indicate malnutrition, low cardiovascular and/or respiratory reserves, reduced endurance, or depression [13].

Grip strength: a simple test where the patient is required to grip a dynamometer, using their dominant hand, as strongly as possible. The test is used to assess muscle strength, and scoring is based on gender and BMI, where a result below the 20th percentile is deemed abnormal [13, 40].

Gait speed: this test is used to measure the normal walking speed of a patient, based on gender and height. The test is repeated three times, and the average time is used for the evaluation. There are several versions of this test, and they vary regarding the start (static or dynamic) and distance to be covered (2–15 m) [41]. The most widely used version is from Fried, which uses 4, 57 m (15 feet) and a dynamic start [13, 25, 34]. Whereas the type of start has been shown not to be relevant, there are several cutoff speeds (m/s) that can significantly predict outcome [42].

Timed Up and Go (TUG) test: this is another version of the gait speed test. Here the patient must stand up from a chair, walk a distance of three meters, turn around, return to the chair, and sit down again. The entire process is timed, whereas a time ≥20 s can be predictive of reduced physical capacity. Ultimately, this test assesses not only mobility, muscle strength, and nutritional status but also cognition and cardiovascular/respiratory reserves [43].

Low levels of activity: self-reported level of activity in terms of kilocalories per week, based on gender, with a cutoff at the lowest 20th percentile [13]. This estimation is rather complex, so that the metabolic equivalent (MET) can be used as an alternative, whereas a MET under 3 is considered abnormal [44].

Modified frailty index (MFI): this compact 11-point questionnaire assesses several domains of frailty, and it is tailored for the acute setting, avoiding elements such as gait speed or grip strength [1].

Activities of daily living (ADL)/instrumental activities of daily living (IADL) [45]: the ADL questionnaire is used to assess the ability of the patient to manage certain activities, such as eating, dressing, and bathing. The IADL encompasses additional activities, such as grocery shopping, cooking, and laundry. These tests, although subject to a ceiling effect, are used to evaluate the physical and cognitive autonomy of the patient [46].

Mini-Mental State Examination (MMSE): this 30-question survey evaluates attention, memory, and visuospatial skills. A score of ≤23 indicates reduced cognitive abilities. Repetitive testing might have an impact on the results, so a second version (MMSE^®-2^™) is required to reduce memory effects [47].

Mini-Cog: this is a short test, requiring less than 5 min to complete, involving a 3-word memory test and clock drawing. It has a similar sensitivity and specificity to cognitive impairment as conventional neuropsychological tests [48].

Geriatric Depression Scale: this is a 15-point questionnaire requiring only yes or no answers. A score of six or above can indicate depression, although a score below six cannot rule out the condition [49].

Social history: should include aspects of social binding (type and frequency of social contacts), living arrangements (house/apartment, stairs/elevator), living alone or with a partner, need and availability of caregivers, access to groceries or healthcare facilities, financial situation, access to immediate help by neighbors and friends, and other factors [38, 50].

Biomarkers: can also be used to assess frailty, as malnutrition and the dysregulation of the immune-endocrine system can lead to reduction in muscle mass, weakness, and chronic inflammation [11]. Such biomarkers include concentrations of albumin, vitamin D and B12, testosterone levels in men, hemoglobin, white blood cell, C-reactive protein, and interleukin-6 levels [51–53].

There are several other aspects that can be easily added to supplement these assessments. Many can be evaluated by simple clinical tests, blood examinations, or from studying the patient’s medical history. In emergency situations, or by centers with limited resources, shorter tests or surrogates are available. Of the previous tests, slow gait speed [54] and grip strength [55] have been shown to be the most relevant in terms of outcome, so that they may be particularly suitable surrogate markers. Low albumin levels, as a marker for sarcopenia and inflammation, was also shown to be a predictor of poorer outcome [56–58].

The implementation of a comprehensive geriatric assessment has shown excellent results in terms of identifying frail patients and improving their outcome. In fact, even non-frail patients can benefit from the systematic and consistent use of this test battery. The study of Hall et al. revealed a decrease in the number of patients who died in the first few days, weeks, and months after major, elective, non-cardiac surgery, showing that preoperative frailty screening could significantly reduce postoperative mortality [5]. After the introduction of screening, the 30-day total mortality fell from 1.6 to 0.7%. When looking exclusively at frail patients, the 30-day mortality rate dropped from 12.2 to 3.8%, but even the mortality rates of non-frail patients fell from 1.2 to 0.3%. A significant decrease in mortality was also seen in frail patients after 180 and 365 days. However, the study did not clarify which medical measures led to such a drastic decrease in postoperative mortality. The authors hypothesized that outcome was improved by multifactorial aspects, such as improved preoperative decision making, intraoperative management, and postoperative measures. Thus, awareness of frailty possibly affects outcome due to a heightened attention to the provision of care.

The primary goal is to identify and evaluate factors that pose a risk to the geriatric patient. Such factors involve emerging or current disabilities and dysfunctions, as well as a reassessment of already diagnosed conditions. Thus, it is often possible to detect disorders at an early stage, where it is feasible (and economic) to contain or reverse their effects through appropriate therapeutic measures.

An individual and interdisciplinary risk assessment is indispensable, and the provision of care to high-risk patients under the aspect of frailty should be carried out as a shared decision process between anesthesiology and the operative disciplines [25]. This leads to reduced rates of institutionalization, 30-day readmission, and costs [59, 60].

Frailty evaluation must be practicable, and the extent and focus of the assessment must be appropriate to the capabilities and goals of the healthcare center. Depending on the goals set, it may be important to establish a selection process for patients suspected of frailty, so as to optimize time and resource investment.

Once frail patients have been identified, priority is to avoid functional decline and ensure short hospitalization periods [61]. There are a number of factors that must be considered to reduce risk to the frail patient, such as prehabilitation measures, type and extent of surgery, choice of anesthesia, as well as postoperative physiotherapy and analgesia. By choosing the treatment goals in a multidisciplinary setting, medical and procedural aspects can be quickly and efficiently addressed.

Establishing the actual state of the patient before the operation can provide healthcare providers with valuable opportunities regarding the optimization of modifiable factors.

Although prehabilitation studies have been relatively small, the use of presurgical exercise and strengthening regimens, some as short as 3 weeks, may already provide significant changes in physical status and outcome [62–64]. Balance, endurance, and resistance exercises should be implemented early in the treatment [65] and continued postoperatively. Outcome parameters, including length of hospitalization, can be affected by the preoperative function [66].

There is a strong synergism between depression and frailty [67, 68], so that depression should be treated as soon as the condition is detected.

Nutritional support should be offered, as the preoperative nutritional status of the patient has been shown to have significant effects in outcome [66, 69]. This may include assessment and counseling by a nutritionist, as well as supplements, such as vitamins D and B12 [70].

Polypharmacy (more than 5 drugs) has been established as a risk factor and even suggested as a surrogate parameter for frailty in acute cases [28, 61]. The critical evaluation of choice and dose of medication can reduce the total medication requirement, either by combined delivery, by dose adaptation, or even by discontinuing unneeded medication.

Social interaction and connections are influential aspects for the elderly frail, and social support should be provided early during treatment [71]. Activate the patient’s social network by encouraging the involvement of family members in the decision making.

Cognitive screening should take place before start of treatment, as reduced cognitive abilities are in itself a risk factor for adverse postoperative outcome and mortality [16]. A preoperative cognitive dysfunction can significantly increase the rate of postoperative delirium, especially among frail patients [16, 72]. Additionally, testing serves as a baseline to detect subsequent cognitive decline.

After addressing all modifiable risk factors, and the patient’s condition has been improved as much as can be reasonably expected, certain aspects of the perioperative management can further protect the frail patient. Although many of these factors should be broadly implemented, frail patients can profit significantly from a strict adherence to these measures.

Clear and realistic goals should be discussed with the patient, keeping in mind their individual risk profile. Fast-track concepts should be preferred, as these patients are particularly vulnerable to the stress of trauma and hospitalization [61].

The invasiveness of the procedure and the time under anesthesia can both influence outcome, so that the type and extent of surgery must be carefully considered. Minimal invasive surgery and short procedures should be favored when possible. Although there is limited evidence that regional or axial anesthesia is preferable to general anesthesia in terms of outcome (possibly due to the regular use of sedatives in awake patients), these methods may provide better analgesia in the postoperative period, reducing stress and supporting physiotherapeutic measures.

Preoperative fasting should be strictly imposed, but beware of dehydration. An increase in the fluid-fasting period is related to an increased rate of postoperative delirium [73]. According to the guidelines [74], encourage the intake of clear fluids up to 2 h before the operation, and should the operation be delayed, consider the provision of intravenous fluids.

Premedication should only be given in exceptional cases, not routinely. The risk of postoperative delirium is severely increased by premedication with benzodiazepines. Though anxiety remains an indication for premedication, a dose reduction is highly advisable. Patients should be monitored after premedication due to the risk of paradox effects or respiratory suppression [75].

In fact, usual pharmacodynamics and pharmacokinetics can be severely altered in elderly patients, particularly in the frail. Several factors, physiological and pathological, serve to enhance the effect of many drugs [76]. Reduced liver and kidney function, reduced albumin (protein binding), dehydration (leading to higher serum concentration), and an overall reduced neural mass, along with changes in neurotransmitter and receptor densities, can prolong and increase the drug effect of many anesthetic drugs (Table 19.3) [61, 77]. Preference should be given to short-acting substances, and dosage should be reduced or titrated to the needs of the patient. Use intraoperative neuromonitoring, and when possible, use drugs that are independent of hepatic or renal elimination, such as remifentanil and cisatracurium [75].

Fluid management is crucial for these patients, and a broad indication should be given to advanced monitoring, such as arterial blood pressure measurements. Beware that many elderly patients, due to restricted compensatory mechanisms, are prone to exaggerated blood pressure responses to anesthetics, blood loss, or inadequate fluid administration. Electrolyte shifts have been associated with POD and should be closely monitored [78, 79], especially in case of impaired kidney function, long procedures, or large fluid shifts. Hypotension is to be avoided, in particular since a reduced cerebral perfusion can contribute to the development of postoperative delirium [80].

Due to reduced muscle mass and reduced metabolism, thermoregulation is also impaired in frail patients. Even mild hypothermia can disrupt circulation and blood clotting, as well as increase the rate of postoperative infections [81]. Warm the patient early during the anesthesia, and monitor temperature throughout the procedure.

According to current guidelines [82], intraoperative monitoring via electroencephalogram (EEG) should be routinely employed in this patient collective. Particular attention should be given to avoid burst suppression periods in the EEG analysis. Burst suppressions imply an excessive level of anesthesia and can have devastating cognitive consequences following surgery [83]. Alpha band coherence in EEG (see Fig. 19.2) can indicate appropriate anesthetic depth, but beware this coherence is reduced in the elderly [84].

Due to dysregulation of pharmacokinetics (impaired elimination, drug distribution, etc.), ensure that no residual neuromuscular block persists before allowing the patient to emerge from anesthesia.

There are several factors that can help reduce perioperative stress. The use of validated instruments to achieve an adequate analgesia can help avoid over- or underdosage of analgesics. Delirium monitoring should be implemented in the recovery room, and the occurrence of POD should be promptly countered with an adequate therapy [79].

In the postoperative phase, it is important to continue the interventions initiated, such as nutritional counseling and physical exercises. Rehabilitation should commence as soon as possible, keeping in mind that hospitalization period should be kept to a minimum.

A proper analgesia protocol using validated scales should be continued, as this not only reduces perioperative stress but also supports physiotherapeutic interventions. Also keep in mind that delirium can still occur several days after surgery, so that proper assessment is also required in peripheral units [85].

Beware of complications, such as pulmonary infections and renal failure. Frail patients are particularly vulnerable to complications during the postoperative phase, as they have a limited ability to compensate the stress of hospitalization and surgical trauma [86, 87].

Social binding should also be utilized. Activated social contacts and visitors can help limit depression and motivate the patient to a speedy recovery by encouraging movement, eating, and drinking, ultimately improving therapeutic compliance [88].

Healthcare systems and hospitals should implement multifaceted strategies delivered by an interdisciplinary team for the entire period of hospitalization, so as to prevent functional and cognitive decline in hospitalized older individuals and maximize their independence at the time of discharge. An example of such a program is the Hospital Elder Life Program (HELP), which was designed to assist older patients retain autonomy, avoid postoperative complications, falls, as well as unplanned readmissions. The HELP staff members, consisting of Elder Life Specialist, Elder Life Nurse Specialist, geriatrician, and trained volunteers, conduct patient-centered interventions, such as the daily visitor program for orientation, social support, exercise program (early mobilization), assistance during meals, education program for family and staff members, and facilitation of the transition from hospital to home [89]. The HELP program has been shown to be effective in the prevention of delirium, cognitive and functional decline, as well as in the reduction of hospitalization length and institutionalization rates [90].