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Ambulatory anaesthesia is a large chapter-level topic in Miller's Anesthesia (10th ed.), covering the whole spectrum of outpatient/same-day surgical care. Rather than dump the entire chapter at once, here's the map of what it covers, then a brief overview so you can pick where to go deep.

Topic Breakdown (per Miller's Anesthesia, 10e - Ambulatory/Non-OR Anesthesia chapter)

Growth and rationale of ambulatory surgery - historical trends, drivers (cost, less invasive techniques, patient preference)
Facilities and models - hospital-integrated units, freestanding ambulatory surgery centers (ASCs), office-based practice
Patient selection criteria - comorbidity considerations, ASA status, age, BMI, obstructive sleep apnea, social/logistic factors (no absolute cut-offs by age/BMI/ASA class)
Procedure selection - which surgeries are appropriate for an ambulatory basis
Preoperative assessment and preparation - screening, testing, patient education, fasting guidelines
Anesthetic techniques - general anesthesia (agent choice for fast recovery), regional/neuraxial blocks, peripheral nerve blocks, MAC/sedation, local infiltration
Postoperative nausea and vomiting (PONV) prophylaxis and management - specific to the ambulatory setting since it drives unplanned admission
Postoperative pain management - multimodal analgesia, regional techniques, take-home analgesia
Recovery pathways - Phase I vs Phase II PACU, fast-tracking criteria
Discharge criteria - scoring systems, street-fitness, escort requirements
Adverse effects and complications after ambulatory surgery - unplanned hospital admission, readmission rates
Outcome measures and quality indicators - IAAS-suggested indicators, benchmarking
Patient satisfaction - measurement and drivers

Brief Overview

Ambulatory (same-day/outpatient) surgery has grown steadily, driven by minimally invasive surgical techniques, refined anesthetic agents with faster offset, and improved patient selection/preparation processes. Miller's stresses that there are few absolute contraindications to ambulatory surgery - patients should not be excluded purely on the basis of age, BMI, or ASA physical status; selection should instead be individualized, weighing comorbidity control, procedure invasiveness/expected postoperative course, and home support/logistics (a responsible escort and appropriate aftercare environment).

Facilities range from hospital-integrated ambulatory units (useful when escalation of care may be needed) to freestanding ASCs and office-based settings (lower overhead, higher efficiency for low-risk cases). Effective preoperative assessment is described as essential to safe, efficient care - identifying and optimizing comorbidities (e.g., OSA, diabetes, cardiopulmonary disease) well before the day of surgery to avoid late cancellations.

Anesthetic technique is chosen to balance rapid, clear-headed recovery with good analgesia: short-acting general anesthetics, regional and peripheral nerve blocks (increasingly favored because they reduce opioid use and PONV while improving analgesia), and MAC/sedation for minor procedures. PONV prophylaxis is emphasized heavily because nausea/vomiting is one of the leading causes of unplanned overnight admission and poor satisfaction; multimodal prophylaxis (risk-stratified, using antiemetics from different classes plus opioid-sparing analgesia) is standard.

Recovery is organized into fast-track pathways (bypassing traditional Phase I PACU when criteria are met) with structured discharge criteria (stable vital signs, adequate pain control, ability to ambulate/tolerate fluids where required, and a responsible adult to accompany the patient home). The chapter also reviews adverse events after discharge, quality/outcome indicators recommended by the International Association for Ambulatory Surgery (IAAS), and patient satisfaction data, all used to benchmark and improve ambulatory programs.

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Topic Breakdown (per Miller's Anesthesia, 10e - Ambulatory/Non-OR Anesthesia chapter)

Growth and rationale of ambulatory surgery - historical trends, drivers (cost, less invasive techniques, patient preference)
Facilities and models - hospital-integrated units, freestanding ambulatory surgery centers (ASCs), office-based practice
Patient selection criteria - comorbidity considerations, ASA status, age, BMI, obstructive sleep apnea, social/logistic factors (no absolute cut-offs by age/BMI/ASA class)
Procedure selection - which surgeries are appropriate for an ambulatory basis
Preoperative assessment and preparation - screening, testing, patient education, fasting guidelines
Anesthetic techniques - general anesthesia (agent choice for fast recovery), regional/neuraxial blocks, peripheral nerve blocks, MAC/sedation, local infiltration
Postoperative nausea and vomiting (PONV) prophylaxis and management - specific to the ambulatory setting since it drives unplanned admission
Postoperative pain management - multimodal analgesia, regional techniques, take-home analgesia
Recovery pathways - Phase I vs Phase II PACU, fast-tracking criteria
Discharge criteria - scoring systems, street-fitness, escort requirements
Adverse effects and complications after ambulatory surgery - unplanned hospital admission, readmission rates
Outcome measures and quality indicators - IAAS-suggested indicators, benchmarking
Patient satisfaction - measurement and drivers

Brief Overview

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Reading File

Ambulatory Anesthesia — Miller's Anesthesia, 10th Edition (Chapter 68)

1. History and Rationale

Ambulatory (same-day/outpatient) surgery is not a modern invention. James Henderson Nicoll performed almost 9,000 ambulatory procedures on children in Glasgow between 1898-1908, encouraging early mobilization against the prevailing dogma of prolonged bed rest. Ralph Milton Waters opened the Downtown Anesthesia Clinic in Sioux City, Iowa shortly after, discharging adults home within hours of dental extractions, abscess drainage, or minor fracture reduction. The first hospital-based ambulatory units opened in Grand Rapids (1951) and Los Angeles (1952); the first freestanding ambulatory surgery center (ASC) opened in Phoenix, Arizona in 1970. Growth since then has been driven by less invasive surgical techniques, better patient selection/preparation, and expansion of non-operating-room and office-based anesthesia.

2. Benefits

Ambulatory surgery requires reduced tissue trauma, enhanced recovery with minimal adverse events, effective postoperative analgesia, and good patient education/support. Patients benefit from more efficient scheduling and recovering in the comfort of home. Financially, both US insurers and the UK NHS pay procedures compatible with ambulatory care at a fixed rate regardless of length of stay - so if a patient stays overnight unnecessarily, the facility absorbs the extra cost. Since 2010, the UK has offered higher tariffs for procedures done on an ambulatory basis specifically to incentivize best practice.

3. Facilities — Four Models of Care

Hospital integrated — shares inpatient OR facilities with separate prep/recovery areas for ambulatory patients. Simplest and most flexible, but often inefficient (ambulatory cases risk being delayed/cancelled for urgent inpatient work) unless strict dedicated-session protocols are used.
Hospital self-contained — functionally/structurally separate unit (own reception, ORs, recovery, admin) within the hospital campus. Patient-focused flow, insulated from emergencies, while still able to draw on hospital resources if escalation is needed. Considered close to an ideal model, though capacity limits and equipment duplication can occur.
Freestanding ASC — complete separation from inpatient/emergency work, maximizing efficiency and standardization, but with no immediate access to a hospital's escalation resources.
Office-based — the fourth model, lowest overhead, used for lower-acuity procedures (mentioned alongside the others as part of the four-model framework).

Accreditation in the US/Canada comes through The Joint Commission (TJC), DNV, Healthcare Facilities Accreditation Program (hospital-based), or AAAHC/AAAASF/TJC (ASCs and office-based sites); CMS runs its own inspection program.

4. Procedure Selection

A very wide range of procedures is now performed ambulatory, across essentially every specialty:

Specialty	Examples
Breast	Excision/biopsy, sentinel node biopsy, simple mastectomy
General surgery	Hernia repair (open/lap), laparoscopic cholecystectomy, adrenalectomy, splenectomy, fundoplication
Gynecology	Laparoscopic tubal ligation, oophorectomy, hysterectomy
Head & neck	Dental procedures, thyroidectomy, parathyroidectomy
Ophthalmology	Cataract surgery, strabismus, vitrectomy
Orthopedics	Arthroscopy, ACL repair, carpal tunnel release, total joint arthroplasty
ENT	Tonsillectomy/adenoidectomy, endoscopic sinus surgery
Urology	Transurethral laser prostatectomy, laparoscopic nephrectomy, prostatectomy
Vascular	Varicose vein surgery, dialysis fistula creation

Cataract surgery gets special mention — done under topical anesthesia with minimal sedation and minimal physiologic stress, so very few comorbidities preclude it (recent MI within 30-60 days, recent PCI, decompensated heart failure, malignant hypertension, DKA/HHS are the main exclusions). Routine preoperative testing is not recommended but still overused in practice, adding cost without benefit.

5. Patient Selection

The chapter is explicit: few absolute contraindications exist. Rigid criteria historically used mostly predicted treatable perioperative events, not the actual need for admission. Overall perioperative mortality for ambulatory surgery is under 1 in 11,000 — safer than the general population baseline.

ASA status/age/BMI: none should be used as an arbitrary cutoff. Increasing ASA class does raise complication/readmission/mortality risk in a stepwise fashion, but there's no evidence overnight admission mitigates that risk.
Obesity: creates logistical challenges (equipment, staffing) but does not independently increase unanticipated admission, complications, or readmission. Even morbid (BMI >40) and super obesity (BMI >50) are no longer absolute contraindications — early mobilization, short-acting drugs, and opioid-sparing analgesia are the key strategies.
Obstructive sleep apnea (OSA): most patients can be managed ambulatory safely; airway obstruction/difficult intubation should be anticipated. STOP-Bang screening identifies high-risk patients; more invasive surgery, airway/chest procedures, or high perioperative opioid requirements make a patient less suitable. Even pediatric tonsillectomy for OSA can be safely done same-day absent other comorbidities.
Age/frailty: assessed via frailty scales (e.g., the Clinical Frailty Scale — from "very fit" through "moderately frail: needs help with all ADLs" to "severely frail: completely dependent").
Cardiovascular disease: hypertension is the most common reason for delay/cancellation, but is not an independent risk factor if diastolic BP <110 mmHg — deferring surgery for hypertension control has no proven benefit. Chronic cardiac meds (especially beta-blockers) should be continued through the day of surgery; ACEIs/ARBs are now generally held on the day of surgery given evidence of increased mortality/stroke/MI risk when continued. Severe unstable angina is a genuine exclusion; post-MI/revascularization risk returns to baseline by 3 months. Exercise tolerance (inability to climb a flight of stairs, ~4 METs) is 89% predictive of postoperative cardiopulmonary complications. Pulmonary hypertension requires specialist centers with ICU backup.
Anticoagulation/antiplatelet therapy: requires individualized bleeding-vs-thrombosis risk balancing.

6. Anesthetic Technique

No single ideal technique exists — choice depends on surgical/patient factors, but the shared goal is controllable intraoperative conditions plus rapid recovery with minimal side effects.

General anesthesia remains the most popular technique with patients and surgeons, sometimes despite clear benefits of regional/local alternatives. Induction is via rapid short-acting IV agents (or inhalational in children/needle-phobic adults); maintenance can be IV (TCI systems) or short-acting volatile agents without N2O (favored for ease of use and lower awareness risk).
IV induction agents: barbiturates, benzodiazepines, and ketamine are essentially historical for this setting. Etomidate causes myoclonus, injection pain, high PONV, and adrenal suppression concerns. Propofol remains the most practical IV anesthetic — smooth induction, no airway irritation, rapid recovery, low early PONV, "clear head." Downsides: injection pain (mitigated by large antecubital vein or lidocaine + venous occlusion), involuntary movements, transient apnea, hypotension. Co-induction strategies (low-dose midazolam, propofol "autoinduction" with an initial 30 mg bolus, or IV lidocaine 1 mg/kg per ERAS principles) reduce propofol dose/hypotension without necessarily delaying recovery; opioid co-induction (fentanyl/alfentanil) improves LMA conditions but raises PONV and prolongs respiratory depression.
Regional/neuraxial: spinal anesthesia extends the range of ambulatory candidates for lower-extremity/perineal surgery, but low-dose bupivacaine or newer agents (chloroprocaine, prilocaine, mepivacaine) are preferred to avoid residual motor/sympathetic block that delays discharge.
Peripheral nerve blocks (PNBs): excellent postoperative analgesia and reduced PONV, but only used in ~3.3% of appropriate US ambulatory cases despite this benefit (per a study of ~13 million patients). Ultrasound guidance shortens block placement/onset time and improves success, though it hasn't been proven to reduce nerve injury.
Local infiltration: simple wound infiltration can match central/proximal blocks for many procedures and allows faster mobilization. Local anesthetic systemic toxicity (LAST) is a real risk even from subcutaneous infiltration (11% of reported LAST cases); awareness of lipid emulsion rescue therapy among non-anesthesia providers is poor (only 2% aware in one survey).
Local infiltration analgesia (LIA): a specific technique for major ambulatory orthopedic surgery (originally hip/knee) — infiltrating ropivacaine + ketorolac + epinephrine into all surgical tissue planes ± a wound catheter for redosing. Shown to reduce pain/opioid use and shorten length of stay after arthroplasty, though benefit is mainly in the first 24 hours.
Sedation/MAC: facilitates many hospital, office, or remote-setting procedures, but the text stresses sedation is no safer than general anesthesia and needs identical standards of personnel, monitoring, and perioperative care.

7. Recovery

The Modified Aldrete Recovery Score (activity, respiration, circulation, consciousness, oxygenation — each 0-2, max 10) determines fitness for discharge from Phase I recovery (score ≥9). White and Song added pain and PONV categories to create a fast-track score, since Aldrete alone doesn't capture those.

Fast-tracking — bypassing Phase I and going directly to Phase II (step-down) recovery — is standard after local anesthesia and appropriate for many sedation and low-dose spinal cases; it's increasingly used after general anesthesia too, since it improves patient experience and frees Phase I resources for patients who truly need them.

8. PONV Prophylaxis and Management

PONV risk should be assessed per patient, with prophylaxis for anyone with risk factors, and combination/multimodal regimens for high-risk patients or procedures.

Antiemetic classes:

Metoclopramide — weak evidence at standard 10 mg dose; higher doses (20-25 mg) more effective but more akathisia; not first-line in current guidelines.
Droperidol — effective at low doses (≤1.25 mg) despite the FDA black-box warning (QT prolongation) that was issued for higher doses; US use has fallen mainly for medicolegal rather than efficacy/safety reasons.
Antihistamines — particularly effective for vestibular-triggered nausea (strabismus, middle ear surgery); dimenhydrinate is comparable to droperidol/5-HT3 antagonists; meclizine is inexpensive, minimally sedating, OTC, and good for postdischarge nausea and vomiting (PDNV).
Transdermal scopolamine — delivers 1 mg over 3 days, onset delayed 2-4 hours, but one of few agents effective well into the postdischarge period; dry mouth is the main side effect.
5-HT3 antagonists (ondansetron etc.) — most effective given near the end of surgery; better at preventing vomiting (NNT 4) than nausea (NNT 7); side effects include headache and QT prolongation. Palonosetron's long half-life (40 hours) may give better postdischarge protection but costs more.
Dexamethasone — effective IV at 4-8 mg, likely via endorphin modulation or prostaglandin inhibition; delayed onset means it should be given right after induction; higher doses (~8 mg) also improve postoperative pain and quality of recovery.
NK-1 antagonists (aprepitant) — particularly good at preventing vomiting specifically; reserved for very high-risk patients given cost.
Managing persistent symptoms: rule out hypovolemia, infection, or other organic causes before symptomatic treatment; 20 mL/kg isotonic fluid reduces nausea/dizziness; ephedrine 0.5 mg/kg IM is an effective alternative; don't re-dose the same antiemetic within 6 hours.

9. Pain Management

Multimodal analgesia — combining local/regional anesthesia, acetaminophen, and NSAIDs — is recommended whenever possible, since reduced opioid need lowers adverse effects and admission risk.

Opioid-related strategies: strong opioids (morphine, oxycodone) remain necessary as rescue after more invasive surgery but carry more side effects. Tramadol (dual opioid/nonopioid mechanism) is effective but still causes sedation, dizziness, and PONV. Tapentadol has comparable efficacy to oxycodone with fewer GI effects and no need for metabolic activation. Combination oxycodone-naloxone reduces opioid-induced constipation with little analgesic penalty (due to naloxone's first-pass metabolism). Alvimopan (peripheral mu-opioid antagonist) targets opioid-induced constipation, delayed gastric emptying, and possibly opioid-related PONV and urinary retention.
Home local anesthetic techniques: perineural or incisional catheters, including patient-controlled regional anesthesia (PCRA) via elastomeric pumps, are increasingly used post-discharge. Continuous interscalene catheters can expedite same-day discharge after shoulder surgery. Caution: local anesthetics are chondrotoxic to articular cartilage in vitro, and intra-articular catheters after shoulder/knee surgery have largely been abandoned due to chondrolysis risk.

10. Discharge Criteria and Aftercare

Discharge is a physician responsibility (per ASA guidelines) fulfilled through written criteria. Example from Brigham and Women's Hospital (Box 68.3):

Alert and oriented to time/place
Stable vital signs
Pain controlled by oral analgesia
Nausea/emesis mild if present
No unexpected bleeding
Able to walk without dizziness
Given discharge instructions/prescriptions
Patient accepts readiness for discharge
Adult present to accompany home

Alternatively, a formal scoring tool — the Postanesthetic Discharge Scoring System (PADSS) — grades vital signs, activity/mental status, pain/nausea/vomiting, surgical bleeding, and oral intake/voiding (each 0-2). Voiding is no longer a mandatory prerequisite for low-risk patients, even after spinal anesthesia; higher-risk patients get bladder ultrasound instead. Discharge is frequently nurse-managed once protocol criteria are met.

There's no evidence for a mandatory minimum observation period in most cases — except possibly tonsillectomy, where 4-8 hours has been advocated to catch primary hemorrhage (though even this is now contested, with some data supporting 4 hours or less as safe).

Aftercare: written instructions (verbal retention is impaired right after anesthesia), a 24-hour contact number, and clear early-warning signs/actions. Smartphone-app-based home recovery monitoring has improved patient reassurance and quality-of-recovery scores and can be more cost-effective than routine nurse phone calls (though a simple phone call was similarly effective in some studies).

11. Adverse Effects

Minor adverse events are common (86% of patients) — drowsiness (62%) is the most frequent lingering effect; sore throat and general aches occur in ~47-49% of intubated patients; headache (25%) and dizziness (20%) are common; nausea/vomiting after discharge is less common (17% and 7% respectively). Patients often need 2-3 days to resume usual activity. Acute cardiovascular events (hypertension/hypotension, dysrhythmia, ischemia, arrest) occur in ~2.9% overall (higher with preexisting cardiac disease); respiratory events (hypoxemia, laryngospasm, bronchospasm, aspiration) occur in ~0.1% (higher in smokers, asthmatics, obese patients). Unanticipated overnight admission occurs in 1-6% worldwide — but this metric must be interpreted cautiously since overly conservative patient selection can artificially lower it.

12. Outcome Indicators and Patient Satisfaction

The International Association for Ambulatory Surgery (IAAS) suggests tracking: failure to attend, cancellation after arrival, unplanned same-day return to OR, unplanned overnight admission, and unplanned return/readmission (<24h and 24h-28 days), each with categorized reasons (medical, anesthetic, surgical, social/organizational).

A broader outcome measures framework spans four domains:

Clinical — cardiovascular/respiratory events, minor morbidity (pain, PONV, sore throat, headache, drowsiness), unplanned OR return, unplanned admission/readmission
Organizational — proportion of elective surgery done as day case, program accessibility, cancellation rates
Social — patient satisfaction, functional health status/quality of life
Economic — OR utilization efficiency

Patient satisfaction is generally very high after ambulatory surgery. Key drivers identified in studies include friendly staff, surgeons discussing findings before discharge (rated more important by patients than pain control itself in some studies), accurate preoperative information about the process, effective analgesia, minimal PONV, courtesy/privacy, short waiting times, absence of a "rushed" feeling, and postoperative telephone follow-up.

Source: Miller's Anesthesia, 2-Volume Set, 10th Edition, Chapter 68 "Ambulatory Anesthesia."

A quick check for very recent evidence: since this chapter's core principles (patient selection, multimodal PONV/analgesia, fast-track recovery) are well-established and not areas of rapid current controversy, I did not find a compelling reason to expect recent meta-analyses to substantially contradict this material. If you want, I can run a targeted PubMed search on a specific sub-topic (e.g., latest PONV prophylaxis guidelines or regional anesthesia outcomes) for the newest trial data.

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