17.3 Ambulatory Day-Surgery Selection, Premedication, and Elderly Patient Anaesthesia

17.3 Ambulatory Day-Surgery Selection, Premedication, and Elderly Patient Anaesthesia

Ambulatory (day-case) surgery has expanded exponentially, encompassing increasingly complex procedures in older, multimorbid patients. Successful day-care pathways require rigorous patient selection, multimodal opioid-sparing protocols, and objective discharge criteria, alongside deep mastery of the physiological senescence and cognitive vulnerabilities of the geriatric surgical cohort.

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1. Ambulatory Day-Surgery: Patient Selection, Surgical Criteria, and Social Determinants

Modern day-surgery criteria have shifted away from arbitrary chronological age, isolated BMI cut-offs, or diabetes labels to functional physiological stability and procedure-specific risk stratification.

Patient Selection Criteria

• ASA Physical Status:
  • ASA Class I and II patients are ideal candidates.
  • Stable ASA Class III patients with medically optimized, non-fluctuating chronic diseases (e.g. well-controlled hypertension, compensated congestive heart failure, stable COPD, medically managed diabetes) are safe for ambulatory surgery provided the surgical procedure does not disrupt chronic physiological homeostasis.
  • Unstable ASA III or ASA IV patients (e.g. unstable angina, decompensated heart failure, severe pulmonary hypertension) require inpatient admission and post-procedure monitoring.
• Obesity and Obstructive Sleep Apnea (OSA):
  • Elevated BMI alone is not an exclusion criterion. However, patients must be screened for OSA using the STOP-Bang questionnaire (high risk: score $\ge 5$, or score $\ge 3$ with elevated serum bicarbonate $>28\text{ mmol/L}$ or $\text{BMI} > 35\text{ kg/m}^2$).
  • Patients with confirmed or suspected severe OSA can safely undergo ambulatory surgery if: comorbidities are optimized, the surgery is superficial or peripheral, airway management is uncomplicated, multimodal non-opioid analgesia is utilized, and the patient is capable and compliant with using their own continuous positive airway pressure (CPAP) machine in recovery and at home.

Surgical Procedure Criteria

• Anticipated operative duration generally $<2 - 3\text{ hours}$.
• Negligible risk of massive haemorrhage, major visceral perforation, extensive fluid shifts, or airway compromise.
• Postoperative pain must be readily controllable with oral multimodal analgesia or peripheral regional blocks.
• Expected low incidence of severe postoperative nausea and vomiting (PONV).

Social and Environmental Determinants

• Escort Requirement: A responsible, competent adult must accompany the patient home and remain present for the first 24 hours postoperatively.
• Domestic Environment: Access to an indoor telephone, adequate sanitation, and absence of physical environmental hazards (e.g., steep unassisted staircases).
• Proximity to Emergency Care: Travel time from the patient's home to an emergency medical facility or surgical center should generally not exceed 60 minutes.

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2. Enhanced Recovery After Surgery (ERAS) in Ambulatory Practice

Day-surgery pathways represent the pinnacle of ERAS implementation, optimizing physiological homeostasis to achieve rapid functional recovery.

                     [ AMBULATORY ERAS PATHWAY ]
                                  |
      +---------------------------+---------------------------+
      |                           |                           |
[ Preoperative ]           [ Intraoperative ]          [ Postoperative ]
- 2h clear fluid fast      - Opioid-sparing multimodal - Early oral hydration
- Carbohydrate loading       analgesia (NSAIDs, COX-2) - Prompt ambulation
- Avoid benzodiazepines    - Multimodal PONV prophy-   - Discontinue IV lines
- Patient education          laxis (Apfel score)       - Verify PADSS score >=9
                           - Regional/fascial blocks     prior to discharge

Core ERAS Elements

1. Preoperative Optimization & Fasting Guidelines:
   • Minimize preoperative fasting: clear liquids (water, pulp-free juice, black coffee/tea) allowed up to 2 hours prior to induction; light meals permitted up to 6 hours.
   • Preoperative Carbohydrate Loading: $400\text{ mL}$ of a complex carbohydrate drink 2 hours before surgery attenuates surgical-stress-induced insulin resistance, maintains glycogen stores, and mitigates preoperative thirst, anxiety, and nausea.
   • Avoidance of Sedative Premedication: Routine administration of long-acting benzodiazepines (e.g. diazepam, lorazepam) is avoided; it delays psychomotor recovery, increases PACU length of stay, and elevates delirium risk.
2. Intraoperative Strategies:
   • Multimodal Opioid-Sparing Analgesia: Scheduled paracetamol ($1\text{ g}$ IV/PO), non-steroidal anti-inflammatory drugs (NSAIDs, e.g. ketorolac, ibuprofen) or COX-2 inhibitors (e.g. parecoxib, celecoxib), combined with surgical local anaesthetic infiltration or ultrasound-guided fascial plane blocks (e.g. TAP, rectus sheath, ESP, adductor canal blocks).
   • Rational PONV Prophylaxis: Guided by the Apfel risk score (female sex, non-smoker, history of PONV/motion sickness, expected postoperative opioid use; each factor confers $\sim 20\%$ incremental risk). High-risk patients receive multimodal combination therapy: IV dexamethasone ($4 - 8\text{ mg}$ at induction), a $5\text{-HT}_3$ antagonist (ondansetron $4\text{ mg}$ at emergence), droperidol ($0.625 - 1.25\text{ mg}$), and consideration of total intravenous anaesthesia (TIVA) with propofol.
3. Postoperative Recovery: Early oral fluid intake, rapid discontinuation of intravenous infusions, and immediate mobilization within 1 to 2 hours.

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3. Post-Anaesthesia Discharge Scoring System (PADSS)

The Post-Anaesthesia Discharge Scoring System (PADSS) provides a validated, objective framework for assessing patient readiness for home discharge.

Discharge Criteria and Modern Practice Updates

• Threshold Score: A cumulative score of $\ge 9$ out of 10 is required for home discharge.
• Veto Rule: No individual category may receive a score of 0.
• Modern Revision on Mandatory Voiding and Drinking: Historical mandates that all day-surgery patients must void urine and tolerate oral fluids prior to discharge have been abandoned. Mandatory pre-discharge voiding is now restricted solely to patients at high risk of urinary retention (e.g. following neuraxial anaesthesia, pelvic/perineal/groin surgery, history of benign prostatic hyperplasia or postoperative urinary retention). Enforcing mandatory drinking delays discharge and can provoke vomiting in otherwise comfortable patients.

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4. Anaesthesia for the Elderly and Frail Patient: Frailty Assessment

Chronological age is a poor predictor of perioperative risk; biological frailty governs outcomes.

Clinical Concept of Frailty

Frailty is a multidimensional biological syndrome defined by decreased physiological reserve and diminished resistance to stressors across multiple organ systems. It results from cumulative subclinical cellular and physiological decline.

• Assessment Tools:
  • Clinical Frailty Scale (CFS by Rockwood): A 9-point visual and descriptive clinical tool ranging from 1 (Very Fit) to 9 (Terminally Ill). A CFS score $\ge 5$ (mildly frail, moderately frail, severely frail, very severely frail, or terminally ill) identifies clinical frailty.
  • Fried Frailty Phenotype: Evaluates 5 physical components: unintentional weight loss ($>4.5\text{ kg}$ in past year), self-reported exhaustion, low physical activity, slowed walking speed ($>6 - 7\text{ s}$ for $4.5\text{ m}$), and muscle weakness (diminished grip strength). Meeting $\ge 3$ criteria confirms frailty (1-2 criteria denotes "pre-frail").
• Prognostic Impact: Frailty is an independent, powerful predictor of 30-day perioperative mortality, major postoperative morbidity, surgical site infection, institutionalization, failure to rescue, and postoperative delirium.

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5. Physiological Senescence and Organ System Vulnerabilities

Ageing is characterized by progressive organ atrophy, structural stiffening, and loss of functional reserve.

Cardiovascular Senescence

• Arterial Stiffening: Fragmentation of elastin fibers and cross-linking of collagen in large conduit vessels (aorta and central arteries) reduce arterial compliance, accelerating pulse wave velocity. This produces elevated systolic blood pressure, widened pulse pressure, and increased left ventricular afterload.
• Diastolic Dysfunction: Progressive concentric left ventricular hypertrophy (LVH) and impaired active myocardial relaxation shift ventricular filling from early diastole (passive ventricular filling, E wave) to late diastole (active atrial contraction, A wave).
• Reliance on "Atrial Kick": In healthy young individuals, atrial contraction accounts for $15 - 20\%$ of left ventricular end-diastolic volume (LVEDV). In the elderly with stiff, non-compliant ventricles, active atrial contraction provides $30 - 40\%$ of ventricular filling. Consequently, loss of sinus rhythm (e.g. new-onset atrial fibrillation or junctional rhythm) precipitates sudden, severe hemodynamic collapse and pulmonary oedema.
• Blunted Baroreceptor Reflex & $\beta$-Adrenergic Desensitization: Downregulation of cardiac $\beta_1$-adrenoceptors, decreased intrinsic pacemaker cells in the sinoatrial node, and stiffening of carotid/aortic baroreceptors blunt reflex chronotropic responses. The elderly patient cannot mount compensatory tachycardia in response to vasodilation or hypovolemia, resulting in profound hypotension upon induction.

                    [ CARDIOVASCULAR SENESCENCE ]
                                  |
      +---------------------------+---------------------------+
      |                                                       |
[ Arterial Stiffening ]                               [ Diastolic Dysfunction ]
- Loss of elastin; increased collagen                 - Concentric LV hypertrophy
- Increased pulse wave velocity                       - Impaired active relaxation
- Elevated systolic BP; widened PP                    - Severe reliance on "Atrial Kick"
      |                                                 (supplies 30-40% of LVEDV)
      +---------------------------+---------------------------+
                                  |
           [ Autonomic Blunting & Downregulated Beta-1 ]
           - Inability to mount compensatory tachycardia
           - Precipitous hypotension on anaesthetic induction

Respiratory Senescence

• Thoracic & Lung Mechanics: Calcification of costochondral junctions and progressive kyphoscoliosis reduce chest wall compliance. Concurrently, loss of pulmonary elastic recoil ("senile emphysema") increases lung parenchymal compliance and air trapping.
• Closing Capacity ($CC$) Elevation: Loss of alveolar tethering forces dynamic small airway closure at higher lung volumes. While in young adults closing capacity lies well below functional residual capacity ($FRC$):
  • At age 44: Closing capacity equals FRC in the supine position ($CC \ge FRC$).
  • At age 65: Closing capacity equals or exceeds FRC even in the upright sitting position ($CC \ge FRC$).
  • Clinical Impact: In the supine position under general anaesthesia (which reduces FRC by an additional $15 - 20\%$), tidal ventilation occurs below closing capacity, precipitating widespread airway collapse, alveolar atelectasis, severe ventilation-perfusion ($V/Q$) mismatch, and rapid arterial hypoxemia during apnea.
• Blunted Ventilatory Drive: Ventilatory responsiveness to hypoxemia is decreased by $\sim 50\%$, and responsiveness to hypercapnia is diminished by $\sim 40\%$, amplifying vulnerability to opioid-induced respiratory depression.

Renal and Hepatic Senescence

• Renal Reserve: Glomerular filtration rate ($GFR$) declines by approximately $1\text{ mL/min/1.73 m}^2\text{ per year}$ after age 40. Renal cortical mass decreases by up to $30\%$, and tubular concentrating and diluting mechanisms deteriorate. Elderly patients are prone to both volume overload and hypovolemia, and exhibit heightened vulnerability to acute kidney injury (AKI) from nephrotoxic drugs (NSAIDs, ACE inhibitors, IV contrast). Sarcopenia causes reduced baseline creatinine production, so serum creatinine remains deceptively "normal" despite marked reductions in GFR.
• Hepatic Clearance: Hepatic parenchymal volume declines by $20 - 40\%$, and hepatic blood flow decreases by $30 - 50\%$. Phase I cytochrome P450 oxidation, reduction, and hydrolysis reactions are significantly impaired, prolonging the clearance of hepatically metabolized drugs (e.g., opioids, local anaesthetics, benzodiazepines). Phase II conjugation (glucuronidation, sulfation) is relatively preserved.

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6. Pharmacological Principles and Dosing Adjustments in Geriatrics

Age-related pharmacokinetic ($PK$) and pharmacodynamic ($PD$) transformations mandate deliberate, proactive drug dose reductions.

Pharmacokinetic Alterations

• Body Composition: Total body water decreases by $10 - 15\%$, lean muscle mass decreases, and body fat percentage increases by $20 - 40\%$.
  • Water-soluble drugs (e.g., neuromuscular blockers, paracetamol) have a smaller initial volume of distribution ($V_d$), leading to higher initial peak plasma concentrations.
  • Lipid-soluble drugs (e.g., fentanyl, diazepam, volatile anaesthetics) have an expanded $V_d$, resulting in significant tissue accumulation, delayed redistribution, and markedly prolonged elimination half-lives ($t_{1/2\beta}$).
• Prolonged Circulation Time: Reduced cardiac output slows arm-to-brain circulation. The peak clinical onset of intravenous induction agents is noticeably delayed. Repeating boluses prematurely results in massive inadvertent overdosing.

Pharmacodynamic Alterations & Practical Dosing Rules

• Intravenous Induction Agents: Sensitivity to propofol and etomidate is markedly increased due to heightened central nervous system receptor responsiveness and reduced central compartment volume. Induction doses must be reduced by $30\% - 50\%$ and titrated slowly over 60 to 90 seconds.
• Volatile Inhalational Anaesthetics: The Minimum Alveolar Concentration (MAC) of volatile agents decreases by approximately $6\%$ per decade of life after age 40. At 80 years, sevoflurane MAC is $\sim 1.6\%$ (compared to $\sim 2.0-2.1\%$ at age 40).
• Neuromuscular Blockers: The onset of non-depolarizing agents (e.g. rocuronium, vecuronium) is delayed due to slow circulation, but their duration of clinical action is prolonged up to 2-fold due to diminished hepatic uptake and renal excretion. Quantitative neuromuscular monitoring (Train-of-Four with acceleromyography or electromyography) is mandatory, targeting a TOF ratio $>0.9$ prior to extubation. Sugammadex provides rapid, complete reversal without the cholinergic/muscarinic side effects of neostigmine.

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7. Postoperative Cognitive Disorders: Delirium vs Cognitive Dysfunction

Postoperative neurocognitive disorders represent the most frequent surgical complication in older adults, linked to increased mortality, prolonged hospitalization, and loss of independent living.

Postoperative Delirium (POD) vs Postoperative Cognitive Dysfunction (POCD)

Deliriogenic Medications to AVOID (The Beers Criteria)

• Benzodiazepines: Lorazepam, diazepam, and midazolam disrupt sleep architecture, inhibit cholinergic transmission, and double the risk of delirium in older adults.
• Centrally-Acting Anticholinergics: Scopolamine, atropine, and first-generation antihistamines (diphenhydramine, promethazine) directly block central muscarinic receptors, precipitating delirium.
• Meperidine (Pethidine): Strictly contraindicated. Its hepatic metabolite, normeperidine, has a prolonged elimination half-life, induces central neurotoxicity, lowers seizure threshold, and precipitates severe delirium.

Multi-Component Non-Pharmacological Interventions

The Hospital Elder Life Program (HELP) bundle provides the strongest evidence for delirium prevention:

1. Early Postoperative Mobilization: Out of bed within 24 hours.
2. Sensory Preservation: Immediate return of spectacles (glasses) and hearing aids in the PACU.
3. Cognitive Reorientation: Clocks, calendars, familiar objects, and family presence.
4. Sleep Hygiene: Consolidating nocturnal sleep by clustering nursing care, eliminating non-essential nocturnal vitals checks, dimming lights, and minimizing monitor alarms.
5. Hydration and Pain Control: Maintaining euvolemia and providing opioid-sparing multimodal analgesia.

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8. Regional vs General Anaesthesia in the Frail Geriatric Cohort

• Evidence from Large-Scale Randomized Trials: The REGAIN trial (NEJM 2021; 1,600 patients) found no difference between spinal and general anaesthesia in death or inability to walk independently at 60 days after hip fracture surgery, and the RAGA trial (JAMA 2022; 950 patients) found no difference in postoperative delirium.
• Advantages of Regional Techniques: Spinal anaesthesia or peripheral nerve blocks (e.g. femoral nerve block, fascia iliaca compartment block, PENG block) provide superior early postoperative dynamic analgesia, significantly reduce systemic opioid requirements, reduce early postoperative nausea/vomiting, and lower the incidence of immediate PACU respiratory depression.
• Hemodynamic Management Under Spinal Anaesthesia: Because elderly patients have non-compliant left ventricles and fixed stroke volumes, sudden sympathetic block-induced vasodilation can precipitate profound coronary and cerebral hypoperfusion. Spinal anaesthesia must utilize low-dose local anaesthetic techniques (e.g. hyperbaric bupivacaine $5 - 7.5\text{ mg}$) accompanied by proactive prophylactic vasopressor infusions (phenylephrine or low-dose norepinephrine) titrated to maintain mean arterial pressure within $10 - 20\%$ of baseline.