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Non-Operative Room Anaesthesia (NORA)

MD Anaesthesia PG Examination - 30 Marks

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DEFINITION AND INTRODUCTION

• Rapid technological advances in minimally invasive/percutaneous procedures
• An aging, medically complex patient population (ASA III-V)
• Increased demand for procedural sedation in diagnostic and interventional suites
• Financial drivers - NORA generates revenue equivalent to OR in many centres

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COMMON LOCATIONS (ASA Classification of NORA Sites)

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ASA GUIDELINES FOR NORA LOCATIONS

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CHALLENGES AND RISK FACTORS IN NORA

A. Patient Factors

• NORA patients are typically older, sicker (ASA III-V) than standard OR patients
• High prevalence of comorbidities: morbid obesity, OSA, GERD, cardiac disease, diabetes
• Unprepared/inadequate pre-procedural evaluation - often booked by non-anaesthesia personnel
• Fasting status frequently non-compliant or unknown
• Patients often referred from outside practitioners with cursory workup

B. Environmental/Logistical Factors

• Suites built without anticipating anaesthesia needs - constrained workspace
• Limited patient access during procedures (prone position, confined tunnels in MRI)
• Dim or variable lighting, cramped spaces
• Unfamiliarity of procedural staff with anaesthesia requirements
• Remote location from OR - help is far away in an emergency
• Radiation hazards (CT, fluoroscopy, angiography suites)
• Magnetic hazards (MRI suite) - extensive equipment constraints
• Non-anaesthesia staff unaware of how to assist the anaesthesiologist

C. Procedure-Related Factors

• Procedures vary in duration and stimulation level unpredictably
• Proceduralists may expand or redirect procedures during the case
• Unrealistic booking times, non-standardized scheduling
• Anesthesiologist may be less familiar with the specific procedure demands

D. Safety Data - ASA Closed Claims

• Remote location claims show a higher proportion of claims for death vs OR claims
• 69% of NORA closed claims involved monitored anaesthesia care (MAC)
• Respiratory events (aspiration pneumonitis, inadequate oxygenation/ventilation) comprised one-third of NORA claims
• Substandard care and non-adherence to ASA monitoring standards were cited as contributing factors

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PRINCIPLES OF NORA - THREE CORE CATEGORIES

NORA Risk Stratification
├── 1. Patient Factors: Comorbidity | Airway | NPO | Monitoring
├── 2. Environmental: Equipment | Emergency gear | Radiation/Magnetic hazards
└── 3. Procedure: Duration | Discomfort | Position | Surgical backup

Pre-Procedural Evaluation Checklist

• Full history and physical, airway assessment
• Review of comorbidities, medications, allergies
• ASA classification
• NPO status: 2 hours clear liquids / 6 hours light meal / 8 hours full meal
• Consent for anaesthesia
• Anticipate need for GA vs sedation vs MAC
• Plan for post-procedure recovery

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ANAESTHETIC APPROACHES IN NORA

1. Minimal Sedation (Anxiolysis)

• Benzodiazepines (midazolam), low-dose opioids
• Patient responds normally to verbal commands
• Suitable for simple, short, minimally stimulating procedures

2. Moderate Sedation / Conscious Sedation

• Benzodiazepines + opioids (midazolam + fentanyl)
• Deliberate but purposeful response to verbal/tactile stimulation
• Airway maintained independently
• Used for: routine colonoscopy, simple EGD, cardiac catheterization (stable patients)

3. Deep Sedation

• Propofol infusion, dexmedetomidine, ketamine
• Not easily arousable, may lose protective airway reflexes
• Assisted ventilation may be required
• Used for: complex endoscopy (ERCP, EUS, endoscopic necrosectomy), EP ablations, paediatric procedures

4. General Anaesthesia (GA)

• Required for: complex neurointerventional, TAVR (with TEE), major interventional radiology, ECT, paediatric imaging, uncooperative adults
• LMA or ETT depending on aspiration risk and access
• TIVA (propofol + remifentanil) is commonly used in NORA to avoid need for scavenging and deliver excellent titration

5. Monitored Anaesthesia Care (MAC)

• Anaesthesiologist present, ready to convert to deeper levels
• Most common NORA technique (>50% of claims involved MAC)
• Includes administration of sedatives/analgesics + standby for GA

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SITE-SPECIFIC NORA CONSIDERATIONS

1. Gastrointestinal Endoscopy Suite

• Airway shared with endoscopist - scope passes through mouth/pharynx
• Aspiration risk (GI pathology, full stomach, obstruction)
• CO₂ insufflation can cause distension, discomfort, perforation
• Complex procedures (ERCP, POEM) require deeper sedation/GA

• Simple EGD/colonoscopy: propofol-based deep sedation or moderate sedation
• High-risk patients (morbid obesity, OSA, GERD, hemodynamically unstable, children): GA with ETT
• ERCP/POEM: GA preferred - shared airway, high aspiration risk, prolonged, stimulating
• Patients with GI hemorrhage/obstruction: RSI with ETT, treat as full stomach
• Topical pharyngeal anaesthesia (lidocaine spray/gargle) reduces sedation requirements for EGD

2. Cardiac Catheterization Laboratory

• Most coronary angiograms: performed by cardiologist with light IV sedation only
• Complex procedures requiring anaesthesiologist: morbid obesity, hemodynamic instability, planned GA for TAVR, EP procedures
• TAVR: GA (with TEE guidance) or local + deep sedation depending on institutional protocol; rapid ventricular pacing employed during valve deployment; potential complications include stroke, coronary occlusion, valve embolization, cardiac tamponade, need for CPB conversion
• MitraClip: GA + TEE mandatory; transseptal puncture performed
• Septal defect closure (ASD/PFO): GA or deep sedation + TEE for guidance

• Anticoagulation affects bleeding risk - know INR, platelet count, recent antiplatelet use
• Contrast nephropathy risk - adequate hydration pre-procedure
• Vasopressors (phenylephrine, norepinephrine) must be immediately available
• Pacing capabilities and external defibrillator must be present

3. Electrophysiology (EP) Laboratory

• Arrhythmia inducibility - certain anaesthetic agents affect this; benzodiazepines + short opioids preferred for diagnostic studies; avoid agents that suppress arrhythmia inducibility
• RF/cryoablation is painful - moderate to deep sedation or GA required
• AF ablation (pulmonary vein isolation): GA preferred - long procedure (2-4+ hours), patient must be still, TEE for thrombus exclusion before cardioversion component
• ICD testing: Ventilation fibrillation induced to test device - deep sedation during shock delivery
• Cardioversion: Short IV anaesthesia - propofol or etomidate + fentanyl; TEE first to exclude LAA thrombus if AF >48h
• Sudden hypotension during EP procedures = suspect pericardial tamponade from catheter perforation

4. MRI Suite

• Zone I: General public area, no restrictions
• Zone II: Interface zone, screened access
• Zone III: MRI control room, restricted - no ferromagnetic items beyond this point
• Zone IV: Bore of magnet - extreme danger zone

1. Projectile/missile effect - ferromagnetic objects (laryngoscopes, O₂ cylinders, stethoscopes) become dangerous missiles near the magnet
2. Implant displacement/heating - pacemakers, cochlear implants, aneurysm clips, metallic prostheses
3. Electrical interference - standard ECG, pulse oximeter leads cause artifact and burns from RF-induced heating
4. Acoustic noise - up to 130 dB; requires ear protection
5. Thermal injury - RF-induced tissue heating, particularly at wire loops

• Non-ferromagnetic (titanium/aluminium/plastic) anaesthesia machine
• MRI-compatible ventilator
• Fibreoptic pulse oximetry, capnography
• Filtered ECG leads (carbon fiber/fibreoptic)
• MRI-safe IV poles, infusion pumps
• Long tubing sets (machine outside Zone IV)
• Cryogenic quench protocol awareness

• Children/claustrophobic adults/disabled patients: GA or deep sedation
• Short procedures: propofol infusion (TIVA) or sevoflurane via MRI-compatible machine
• Long breath-holds required (interventional MRI): GA with neuromuscular blockade + controlled ventilation
• Emergency in MRI: Remove patient from Zone IV immediately before resuscitation
• Quench (emergency release of magnet field) must be performed only by authorized personnel if life-threatening entrapment occurs

5. Radiation Therapy Suite

• Anaesthesiologist must leave the room during radiation delivery (radiation hazard)
• Patient is completely alone during delivery - monitoring via CCTV and remote displays
• Remote controls for anaesthesia equipment essential
• Long working distances - use long IV tubing, long breathing circuits
• Daily short anaesthetics over several weeks (especially paediatric CNS tumours) - cumulative stress of repeated anaesthesias
• Paediatric considerations dominate this location

• Cooperative adults: no anaesthesia needed
• Children: propofol infusion or inhalational (sevoflurane via mask) - brief, daily
• Pre-established venous access on first day; maintained throughout course
• Recovery area immediately accessible

6. Electroconvulsive Therapy (ECT) Suite

• Amnesia and unconsciousness
• Skeletal muscle relaxation (prevent injury from convulsion)
• Minimize cardiovascular side effects
• Rapid recovery (outpatient setting)
• Allow adequate seizure duration (>15-25 seconds EEG seizure)

• Phase 1 (vagal): Bradycardia, hypotension, brief asystole (seconds) following electrical stimulus
• Phase 2 (sympathetic): Tachycardia, hypertension, increased myocardial O₂ demand (lasting 3-5 minutes)
• Elevated ICP transiently
• Raised IOP
• Increased gastric acid secretion

• Induction agent: Methohexital (gold standard - least seizure threshold elevation); alternatives: propofol (reduces seizure duration), etomidate (may prolong seizure), ketamine, thiopental
• Muscle relaxant: Succinylcholine 0.5-1 mg/kg (short-acting, essential); rocuronium + sugammadex reversal if succinylcholine contraindicated
• Preoxygenation → induction → succinylcholine → manual ventilation with 100% O₂ → ECT stimulus → monitor seizure → allow spontaneous breathing → recovery
• Airway: Bite block mandatory; LMA or mask ventilation; ET intubation rarely needed
• Monitoring: ECG, SpO₂, BP, EEG (bilateral frontal leads for seizure monitoring), peripheral nerve stimulator (for NMB monitoring)

• Anticholinergics (glycopyrrolate/atropine) given pre-ECT to reduce vagal bradycardia
• Beta-blockers (esmolol, labetalol) to attenuate sympathetic surge post-ECT
• Caffeine/theophylline to lower seizure threshold if seizures are inadequate
• Benzodiazepines should be withheld the day of ECT (raise seizure threshold)

• Recent MI (<3 months) - relative
• Raised ICP
• Recent stroke
• High-grade aortic stenosis
• Phaeochromocytoma
• No absolute contraindications in life-threatening psychiatric emergencies

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MONITORING STANDARDS IN NORA

1. Pulse oximetry (SpO₂)
2. Non-invasive blood pressure (NIBP)
3. ECG (3 or 5 lead)
4. Capnography (EtCO₂) - especially critical in sedation where airway is not secured
5. Temperature (for long procedures or high-risk patients)
6. Inspired O₂ concentration

• Invasive arterial line (hemodynamically unstable, TAVR, neurointerventional)
• CVP/PA catheter (complex cardiac procedures)
• TEE (structural heart interventions)
• BIS/depth of anaesthesia monitors (TIVA)
• Cerebral oximetry (NIRS) - neurointerventional, TAVR

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DRUGS COMMONLY USED IN NORA

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RECOVERY AND POST-PROCEDURE CARE

• A dedicated recovery/PACU facility must be available for all NORA locations
• Post-anaesthesia discharge scoring (Aldrete score, PADSS) should be used
• Monitored recovery: SpO₂, HR, BP, consciousness, pain, PONV
• Written discharge instructions for outpatients
• Unexpected admissions from NORA must be tracked (quality metrics)

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SPECIAL POPULATIONS IN NORA

• Morbid obesity: Higher OSA risk, difficult airway, GERD; consider ETT over LMA; positioning challenges
• Paediatrics: Highest volume of NORA cases in MRI and radiation therapy; separation anxiety; parental presence for induction; lower margin for error with airway
• Elderly: Multiple comorbidities; reduced drug requirements; prolonged recovery; cognitive impact
• Patients with implants: Pacemakers, cochlear implants, metallic prostheses - screening mandatory before MRI
• Pregnant patients: ECT can be safely performed; positioning to avoid aortocaval compression; fetal monitoring recommended

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ORGANISATIONAL AND SAFETY FRAMEWORK

1. Establish written protocols between anaesthesiology and procedural departments
2. Include NORA cases in the same electronic scheduling database as OR cases
3. Implement real-time scheduling with proper NPO calculation
4. Standardised pre-procedure evaluation forms for each NORA location
5. Anaesthesiology oversight of peri-procedural triage and recovery
6. Regular simulation training for NORA emergencies
7. Track adverse events, unexpected admissions, length of stay as quality indicators
8. Emergency protocols: mock drills for power failure, fire, evacuation, quench (MRI), cardiac arrest in EP lab

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SUMMARY TABLE: KEY FACTS FOR EXAM

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• Miller's Anesthesia, 10th ed., Chapter 69 - Non-Operating Room Anesthesia (Chung & Vazquez)
• Morgan & Mikhail's Clinical Anesthesiology, 7th ed., Chapter 44 - NORA section
• ASA Guidelines for Non-Operating Room Anesthetizing Locations (amended 2008, reaffirmed 2018)
• ASA NORA Safety Guidelines - APSF Safety in NORA