FRAILTY SCORE INDEX IN ANAESTHESIA

Long Answer - MD Anaesthesia Examination

INTRODUCTION AND DEFINITION

Sources: Miller's Anesthesia 10e, Barash's Clinical Anesthesia 9e, Current Surgical Therapy 14e

PATHOPHYSIOLOGY AND MODELS

1. The Frailty Phenotype (Fried Model)

• 0 criteria: Robust / Non-frail
• 1-2 criteria: Pre-frail
• ≥3 criteria: Frail

2. The Deficit Accumulation Model (Rockwood Model)

Frailty Index = Number of positive deficits / Total deficits assessed

VALIDATED FRAILTY ASSESSMENT INSTRUMENTS

A. Clinical Frailty Scale (CFS)

• Takes <2 minutes to administer
• No special equipment or extra space required
• Web-based training modules available for standardised application
• In direct comparison with the modified Fried Index, clinicians found it easier to use, more feasible in clinical settings, and quicker (<1 min vs 5 min)
• Predicts postoperative mortality and non-home discharge
• In systematic review and meta-analysis, the CFS had the strongest accuracy and feasibility among available scales

B. Fried Phenotype (Modified Frailty Phenotype)

C. Edmonton Frail Scale (EFS)

1. Clock drawing test (cognition)
2. Timed Up-And-Go (TUG) test (functional performance)
3. General health status (two questions)
4. Functional independence (ADLs)
5. Social support
6. Medication use (polypharmacy; ≥5 medications)
7. Nutrition (weight loss)
8. Mood (depression screening)
9. Continence
10. Functional performance (TUG)
11. Nine standardized questions

• 0-5: Not frail
• 6-7: Vulnerable
• 8-9: Mild frailty
• 10-11: Moderate frailty
• 12-17: Severe frailty

D. FRAIL Scale

• 0: Robust
• 1-2: Pre-frail
• 3-5: Frail

E. Modified Frailty Index (mFI / mFI-5)

• Major postoperative complications (OR 1.58)
• Prolonged length of stay (OR 1.89)
• Discharge to higher level of care (OR 2.29)
• 30-day mortality (OR 2.05 per 0.1 increase in frailty score)

F. Robinson's Surgical Frailty Definitions

• Mini-Cog score ≤3
• Serum albumin ≤30 g/L
• One or more falls in the prior 6 months
• Haematocrit <35%

• Timed Up-And-Go (TUG) ≥15 seconds
• Activity of daily living (ADL) dependence
• Charlson Comorbidity Index score ≥3

G. Risk Analysis Index (RAI)

COMPARISON TABLE OF FRAILTY TOOLS (Barash 9e, Table 34-1)

PERIOPERATIVE SIGNIFICANCE OF FRAILTY

Association with Adverse Outcomes

• Surgical complications: Frailty is independently associated with higher postoperative complication rates across general surgery, orthopaedic surgery, cardiac surgery, and spine surgery.
• Postoperative delirium: Frailty (especially assessed by Fried Phenotype) is the strongest predictor; incidence of delirium 5-50% in older surgical patients.
• Prolonged hospital stay: Frail patients have significantly longer length of stay.
• Non-home discharge: CFS ≥4 independently predicts discharge to skilled nursing/assisted-living facilities.
• Mortality: 7.7% one-year mortality in frail patients undergoing elective orthopaedic surgery. Degree of frailty independently and dose-dependently predicts readmission or death.
• Frailty augments other risk scores: Adds prognostic value beyond ASA score, RCRI, and Eagle's Cardiac Risk Index.

Current Practice Gaps

1. Focus on cardiorespiratory evaluation
2. Need for more training
3. Absence of formal guidelines for evidence-based frailty assessment
4. Time constraints in busy clinical settings

FRAILTY IN ANAESTHETIC PRACTICE

Preoperative Assessment

• Frailty screening should be incorporated into the preoperative assessment of all patients aged ≥65 years, and younger patients with clinical suspicion of reduced physiologic reserve.
• The CFS is recommended as the most feasible clinical approach: it takes <1 minute, requires no equipment, and has comparable accuracy to longer tools.
• Comprehensive Geriatric Assessment (CGA) - the gold standard - examines: burden of comorbidity, polypharmacy, physical function, psychological status, nutrition, delirium risk, and social support.
• CGA is more powerful than ASA score alone for predicting perioperative risk in older patients (mean age 78 years).

Anaesthetic Implications of Frailty

1. Pharmacokinetics/Pharmacodynamics: Frail patients have reduced muscle mass (sarcopenia), altered body composition, decreased hepatic and renal blood flow - leading to unpredictable drug distribution and prolonged drug effect.
2. Airway management: Reduced physiologic reserve limits apnoea tolerance; careful preoxygenation is essential.
3. Haemodynamic instability: Reduced cardiovascular reserve increases sensitivity to anaesthetic agents and volume changes.
4. Postoperative delirium prevention: Frail patients at high risk; prefer shorter-acting agents, minimise benzodiazepines, use multimodal analgesia.
5. Hypothermia: Reduced muscle mass and subcutaneous fat increase risk.
6. Pain management: Altered pharmacodynamics; opioids require dose reduction.
7. Regional vs general anaesthesia: No definitive evidence that one technique is superior in frail patients, but regional techniques may reduce physiologic stress.
8. Informed consent and goals of care: Frailty identified preoperatively allows for informed shared decision-making and realistic outcome counselling.

Prehabilitation

1. Nutritional assessment and optimisation (increase protein intake)
2. Physical exercise and optimisation of functional status
3. Lifestyle modification (smoking cessation, alcohol reduction)
4. Psychological preparation and stress management

OBJECTIVE/RADIOGRAPHIC MARKERS OF FRAILTY

• Psoas muscle area on CT (marker of sarcopenia)
• Preoperative ultrasound measurement of quadriceps depth - a simple, non-invasive bedside tool for identifying high-risk elderly patients
• These opportunistic imaging-based assessments could help operationalise frailty screening using imaging already obtained for surgical planning.

SUMMARY

CLINICAL FRAILTY SCALE (CFS)

Cited exclusively from Anaesthesia Textbooks

DEFINITION AND CONCEPTUAL BASIS

"Frailty, which is defined as a state of increased vulnerability to physiologic stressors, is associated with adverse health outcomes after medical and surgical interventions and limited life expectancy."

- Miller's Anesthesia, 10e, p. 3857

1. The Frailty Phenotype (Fried et al.) - based on five physical traits
2. The Deficit Accumulation Model (Rockwood et al.) - based on 92 signs, symptoms, functional impairments, and laboratory abnormalities proportionally weighted into a Frailty Index

"The accumulating deficit model was used to develop the nine-level Clinical Frailty Scale (CFS), where frailty is defined by a CFS score ≥4."

- Miller's Anesthesia, 10e, p. 3858

THE CLINICAL FRAILTY SCALE (CFS)

Box 68.1 - Clinical Frailty Scale

Frailty is defined by CFS score ≥ 4

CFS vs. OTHER FRAILTY TOOLS - ANAESTHESIA TEXTBOOK DATA

From Barash's Clinical Anesthesia, 9e (Table 34-1, p. 2717):

KEY STATEMENTS FROM ANAESTHESIA TEXTBOOKS

Miller's Anesthesia, 10e (Preoperative Evaluation Chapter, pp. 3858-3859):

"More recent evidence has pointed to the nine-level CFS as being the most feasible clinical approach to accurately assess frailty during preoperative evaluation. In direct comparison of the CFS against the modified Fried Index, clinicians found the CFS to be easier to use, more feasibly applied in the clinical environment and quicker to complete (<1 minute versus 5 minutes). Web-based training modules have now been developed to support clinicians in applying the CFS in a standardized and reliable manner."

Miller's Anesthesia, 10e (Ambulatory Anaesthesia Chapter, p. 9955):

"Despite chronologic age not being associated with postoperative adverse outcomes, frailty is, with increasing scores on a frailty index associated with a stepwise increase in risk of adverse events after ambulatory surgery. There are several validated scales to assess frailty. One example is the Clinical Frailty Scale detailed in Box 68.1."

"Frailty assessment can be included in patient selection criteria for ambulatory surgery and, importantly, non-frail elderly patients should not be denied ambulatory surgery based on age."

Barash's Clinical Anesthesia, 9e (p. 2716):

"The Clinical Frailty Scale is highly feasible in clinical settings (taking less than a minute or so) and can be useful for postoperative mortality and nonhome discharge risk stratification. The Edmonton Frail Scale is a better predictor of postoperative complications. The Fried Phenotype is strongly associated with postoperative delirium."

Miller's Anesthesia, 10e (Orthopaedic Anaesthesia Chapter, p. 9153):

"A recent systematic review and meta-analysis demonstrated that amongst the available scales, the Clinical Frailty Scale had the strongest accuracy and feasibility."

BARRIERS TO ROUTINE FRAILTY ASSESSMENT

"A survey of 251 surgical oncologists reported that although most surgeons expressed interest in preoperative optimization for older patients, only 6% currently perform geriatric assessments in their older patients. In a recent qualitative study, anesthesiologists and surgeons identified key impediments to more routine frailty assessment as being the need to focus on other clinical domains (i.e., cardiorespiratory health, indication for surgery), as well as need for more training and guidelines on evidence-based efficient frailty assessment."

SUMMARY OF CFS IN ANAESTHETIC PRACTICE

• Miller's Anesthesia, 2-Volume Set, 10e - Box 68.1 (p. 9958); Preoperative Evaluation chapter (pp. 3857-3859); Orthopaedic chapter (pp. 9153-9154); Ambulatory chapter (p. 9955)
• Barash, Cullen, and Stoelting's Clinical Anesthesia, 9e - Chapter 34, pp. 2715-2718, Table 34-1 (p. 2717)

CARDIOPLEGIA

Long Answer - MD Anaesthesia Examination

INTRODUCTION AND DEFINITION

"To provide a motionless field for the surgeon, the heart is arrested in diastole by the administration of a potassium-enriched cardioplegia solution. Cessation of myocardial electromechanical activity is the single most important step in reducing the heart's metabolism." - Miller's Anesthesia, 10e, p. 7558

RATIONALE: MYOCARDIAL ISCHAEMIA DURING CPB

• Depletion of high-energy phosphate compounds (ATP, creatine phosphate)
• Accumulation of intracellular calcium - triggers cellular injury
• Shift to anaerobic metabolism - fatty acid oxidation impaired
• Progressive intracellular acidosis
• Resultant myocardial stunning (reversible) or necrosis (irreversible)

"Ischemia causes depletion of high-energy phosphate compounds and accumulation of intracellular calcium. When coronary blood flow ceases, anaerobic metabolism becomes the principal source of cellular energy... these high-energy phosphate stores are rapidly depleted, producing progressive acidosis." - Morgan & Mikhail's Clinical Anesthesiology, 7e, p. 817

GOALS OF CARDIOPLEGIA

1. Hypothermia - reduces cellular metabolic rate
2. Cardioplegia - arrests electromechanical activity
3. Decompression of the LV - reduces wall tension and O₂ demand

"Myocardial protection of the heart from ischemic damage during CPB is achieved via: institution of hypothermia, induction of cardioplegia to facilitate arrest, and decompression of the LV; the goal is to minimize myocardial metabolic function." - Barash's Clinical Anesthesia, 9e, p. 3339

• Potassium-induced arrest alone: reduces MVO₂ by 90%
• Combined K⁺ arrest + myocardial temperature <22°C: reduces MVO₂ by 97%

MECHANISM OF ACTION

Potassium-Induced Cardiac Arrest

"The resulting increase in extracellular potassium concentration reduces transmembrane potential. Eventually, the heart is arrested in diastole." - Morgan & Mikhail, 7e, p. 819

• Elevated extracellular K⁺ depolarises the resting membrane potential toward the threshold for action potential generation
• The sodium channels become inactivated (in a depolarised state), preventing further action potentials
• The heart arrests in diastole (not systole) - the most energy-efficient state
• Cardiac arrest in diastole is preferred because diastolic arrest:
  • Has the lowest wall tension
  • Has the lowest O₂ demand
  • Provides the best subendocardial protection

COMPOSITION OF CARDIOPLEGIA SOLUTIONS

Essential Ingredients (Morgan & Mikhail, 7e, p. 819)

Multidose Regimen - High-K and Low-K Solutions (Miller's Anesthesia, 10e, p. 7559)

TYPES OF CARDIOPLEGIA

1. Based on Temperature

"The initial dose of cardioplegic solution may be hypothermic or may start warm ('hot shot') and progress to cold." - Morgan & Mikhail, 7e, p. 818

2. Based on Vehicle (Carrier)

A. Crystalloid Cardioplegia

• Simple ionic solutions (no blood component)
• Examples: St Thomas' solution, HTK (Histidine-Tryptophan-Ketoglutarate), del Nido
• Advantages: clear field, uniform distribution, ease of preparation
• Disadvantages: no oxygen-carrying capacity, dilutional effects

B. Blood Cardioplegia

• Blood mixed with crystalloid solution
• Now the dominant approach in North America and most centres globally
• Provides oxygen-carrying capacity
• Buffering capacity of blood proteins
• Blood-to-crystalloid ratios:
  • 4:1 or 8:1 - Buckberg and St Thomas formulas
  • 1:4 (blood:crystalloid) - del Nido formula
  • Pure blood with potassium enrichment - simplest form

"The trend in clinical practice has been not to use purely crystalloid cardioplegia solutions; instead, most centers now use some form of blood cardioplegia." - Miller's Anesthesia, 10e, p. 7558

3. Based on Frequency/Dosing

4. Named Cardioplegia Solutions

St Thomas' Hospital Solution

• Developed at St Thomas' Hospital, London
• Crystalloid-based, cold, hyperkalemic
• One of the most widely used historical formulations
• Blood:crystalloid ratio 4:1 or 8:1

del Nido Solution

• Composition (Barash, 9e, p. 3340): 1 part blood + 4 parts crystalloid + additives:
  • Lidocaine
  • Magnesium sulfate
  • Sodium bicarbonate
  • Mannitol
  • Potassium chloride
• Single-dose solution; safe arrest time: 45 minutes
• Increasingly used in adult cardiac surgery
• Originally developed for paediatric cardiac surgery

HTK Solution (Custodiol)

• Histidine-Tryptophan-Ketoglutarate
• Pure crystalloid
• Single-dose solution; safe arrest time: 90 minutes
• Blood:crystalloid ratio 1:4 (crystalloid dominant)

Buckberg Solution

• Blood-based (4:1 blood:crystalloid)
• Warm induction, then cold maintenance
• "Warm induction + cold maintenance + warm reperfusion (hot shot)" paradigm

ROUTES OF DELIVERY

A. Antegrade Cardioplegia

"In antegrade application, cardioplegia is delivered proximal to the aortic cross-clamp, into the aortic root at a pressure of 60 to 100 mmHg or directly into the coronary ostia if significant AI or coronary artery disease is present." - Barash's Clinical Anesthesia, 9e, p. 3339

• Delivered via a needle/catheter in the aortic root between the cross-clamp and the aortic valve
• Or directly into coronary ostia (when the aorta is opened, e.g., aortic valve replacement, or when significant aortic regurgitation is present)
• Most physiologic route - follows normal coronary flow
• Limitation: Does not reach areas distal to high-grade coronary stenoses; uneven distribution in severe CAD

B. Retrograde Cardioplegia

"In the retrograde application, a catheter is placed inside the coronary sinus and cardioplegia is delivered (200 to 400 mL/min) to a venous pressure of 30 to 50 mmHg." - Barash's Clinical Anesthesia, 9e, p. 3339

• Catheter placed through the right atrium into the coronary sinus
• Perfuses the coronary venous system in reverse
• Bypasses obstructive coronary plaques
• Limitation: Poor distribution to:
  • Free wall of the right ventricle
  • Posterior one-third of the interventricular septum (RCA territory)
  • Microvascular areas less able to sustain normal energy metabolism

C. Combined Antegrade + Retrograde

"The most complete technique for myocardial protection involves both antegrade and retrograde delivery. In fact, it is not uncommon for cardioplegia to be delivered simultaneously in both antegrade and retrograde fashion." - Miller's Anesthesia, 10e, p. 7560

• Superior to either alone
• Used especially in:
  • Severe multi-vessel CAD
  • Aortic regurgitation (prevents antegrade solution regurgitating into LV)
  • Complex procedures with prolonged cross-clamp times

ROLE OF HYPOTHERMIA IN MYOCARDIAL PROTECTION

"For each degree centigrade reduction in temperature below 37°C, cellular metabolism decreases by approximately 8%; at 28°C the metabolic rate falls to 50%." - Barash's Clinical Anesthesia, 9e, p. 3339

• Systemic hypothermia: Mild (>28°C), moderate (20-28°C), deep (<20°C)
• Topical hypothermia: Ice slush applied directly to cardiac surface
• Cardioplegia solution temperature: 4-15°C (target myocardial temperature: 10-15°C)
• Deep hypothermic circulatory arrest (<20°C) used for aortic arch replacement and pulmonary endarterectomy

REPERFUSION AND THE "HOT SHOT"

1. Pre-reperfusion washout: Just before unclamping, a reduced-K⁺ cardioplegic solution washes out accumulated metabolic byproducts
2. "Hot Shot": Warm (normothermic), normokalemic blood cardioplegic solution administered immediately before or after cross-clamp removal:
   • Washes out acidic metabolites
   • Replenishes metabolic substrates (ATP precursors)
   • Allows aerobic metabolism to resume before mechanical load is restored

"To reinstitute the electromechanical activity of the heart, warm, normokalemic blood is infused into the coronary arteries. This may be done by administering a 'hot shot' through the cardioplegia cannulas or by simply removing the cross-clamp." - Miller's Anesthesia, 10e, p. 7560

1. Reperfusion pressures: Controlled closely (altered coronary autoregulation post-ischaemia):
   • Reduce systemic perfusion pressure just before clamp release
   • Raise gradually to ~40 mmHg first, then ~70 mmHg
   • Avoid hypercalcaemia in immediate reperfusion period

ISCHAEMIA-REPERFUSION INJURY

"Following prolonged myocardial ischemic times (cross-clamp times), myocardial reperfusion can lead to the rapid accumulation of intracellular calcium, extensive cell injury, and, potentially, necrosis. Ischemia-reperfusion injury has been attributed to accumulation of oxygen-derived free radicals." - Morgan & Mikhail, 7e, p. 820

• Free radical scavengers (e.g., mannitol) are routinely added to cardioplegic solutions and bypass priming solutions
• Calcium paradox: sudden Ca²⁺ influx on reperfusion causes contracture and cell death
• Sodium paradox: intracellular Na⁺ accumulation during ischaemia activates Na⁺/Ca²⁺ exchanger on reperfusion

MONITORING ADEQUACY OF CARDIOPLEGIA

1. Quiescence of ECG - isoelectric trace confirms arrest
2. Time since last dose - exceed 20-30 min for multidose solutions
3. Myocardial temperature - direct monitoring; target 10-15°C
4. Ventricular chamber filling state - monitored with TEE:
   • If vent lines fail to keep heart empty → rewarming accelerates → protection compromised
   • LV distension increases wall tension and MVO₂

SPECIAL SITUATIONS

Aortic Regurgitation (AI)

• Antegrade cardioplegia regurgitates through incompetent valve into LV instead of coronary ostia
• Solution: Direct coronary ostial cannulation for antegrade delivery + retrograde cardioplegia
• LV distension and failure of rapid electrical arrest are warnings

"Vigilance is recommended, especially in patients with severe AI in whom the leaky valve may allow the antegrade cardioplegia to seep into the LV cavity instead of the coronary ostia." - Barash's Clinical Anesthesia, 9e, p. 3340

Severe CAD

• Antegrade cardioplegia does not reach territories distal to tight stenoses
• Solution: Retrograde delivery + individual graft delivery (after distal anastomoses are completed) + combined antegrade-retrograde

Ventricular Fibrillation during Cooling

• VF occurs when heart cooled below 28-29°C
• VF increases high-energy phosphate consumption much more than sinus rhythm
• Cardioplegia must be established immediately on onset of VF

"Ventricular fibrillation often occurs as the heart is cooled below 28°C to 29°C. Cardioplegia should be established immediately, as ventricular fibrillation consumes high-energy phosphates at a greater rate than slower rhythms." - Morgan & Mikhail, 7e, p. 852

COMPLICATIONS OF CARDIOPLEGIA

"Inadequate myocardial protection or inadequate washout and recovery from cardioplegia can result in asystole, conduction blocks, or a poorly contracting heart at the end of bypass. Excessive volumes of hyperkalemic cardioplegic solutions may produce persisting systemic hyperkalemia." - Morgan & Mikhail, 7e, p. 820

ANAESTHETIC IMPLICATIONS

1. Communication: Anesthesiologist must co-ordinate cross-clamp time, cardioplegia dosing intervals, and myocardial temperature monitoring with the perfusionist and surgeon
2. TEE monitoring: Continuously assess LV filling and function; detect distension during CPB
3. Weaning from CPB: After cardioplegia washout:
   • Confirm regular cardiac electrical activity (pace if needed)
   • Resume lung ventilation
   • Correct metabolic derangements (K⁺, pH, temperature, glucose, haematocrit)
   • Expect transient myocardial stunning - have inotropes ready
4. Post-cardioplegia hyperkalemia: Monitor serum K⁺ before weaning; treat with insulin/dextrose if needed
5. Hot shot timing: Coordinate with surgeon; administered through cardioplegia cannulas or by simply releasing the cross-clamp with warm normokalemic blood perfusing

SUMMARY TABLE

• Miller's Anesthesia, 10e - Chapter on CPB, pp. 7558-7560
• Barash's Clinical Anesthesia, 9e - Myocardial Protection, pp. 3339-3340
• Morgan & Mikhail's Clinical Anesthesiology, 7e - Potassium Cardioplegia, pp. 817-820; Hypothermia & Cardioplegia, p. 852