2.2 General Anaesthesia and Sedation
GS_1.4 Discuss the indications for sedation and the requirements for safe practice of procedural sedation, both within and outside the operating room, refer to ANZCA professional document: PG09(G) Guideline on sedation and/or analgesia for diagnostic and interventional medical, dental or surgical procedures 2014.
Indications for Sedation and Requirements for Safe Practice of Procedural Sedation
Indications for Sedation
Facilitate Patient Comfort and Cooperation:
Reduce anxiety and distress during diagnostic, interventional, or surgical procedures.
Minimize pain, discomfort, and psychological trauma.
Immobility Requirements:
Ensure patient stillness for precise procedures (e.g., imaging, dental work, or endoscopic interventions).
Avoid General Anaesthesia:
Provide sedation as a less invasive alternative to general anaesthesia when appropriate.
Special Populations:
Pediatric patients, individuals with developmental delays, or those with procedural phobia who may benefit from sedation for compliance.
Requirements for Safe Practice of Procedural Sedation
(Referencing ANZCA PG09(G) Guideline on Sedation, 2023)
Staffing and Competency:
Sedationist Qualifications: Practitioners must have training and competencies outlined in the guideline, including airway management and life support skills.
Team Composition: Minimum staff includes a proceduralist, sedationist, and assistant with defined roles. For moderate sedation or complex cases, additional support may be required.
Patient Assessment and Selection:
Comprehensive pre-sedation assessment to identify risks (e.g., comorbidities, obstructive sleep apnoea, ASA status).
Evaluate airway risk, fasting status, and patient-specific vulnerabilities (e.g., age, frailty, history of adverse sedation reactions).
Informed Consent:
Obtain consent detailing the sedation process, risks, and benefits.
For pediatric patients, involve parents/guardians and consider child assent when appropriate.
Monitoring Standards:
Continuous Monitoring: Oxygen saturation (pulse oximetry), heart rate, respiratory rate, and blood pressure.
Advanced Monitoring: Use capnography for moderate sedation, particularly in high-risk patients.
Regular assessment of sedation depth and patient response to verbal/tactile stimulation.
Safety Equipment:
Ensure availability of resuscitation equipment (oxygen supply, suction devices, airway adjuncts).
Emergency drugs (e.g., naloxone, flumazenil) and intravenous access for moderate sedation or deeper levels.
Environment and Facility Requirements:
Adequate space for patient monitoring and resuscitation.
Staff training in emergency response and established escalation protocols.
For pediatric sedation, settings must have age-appropriate equipment and personnel.
Pharmacological Management:
Medication Selection: Use agents with predictable pharmacokinetics and rapid reversibility.
Caution with Polypharmacy: Avoid combinations leading to synergistic deep sedation unless appropriately skilled.
Risk Mitigation:
Prevent Unintended Deep Sedation: Regularly reassess sedation depth and prepare for escalation to general anaesthesia if needed.
Special Populations: Extra caution with children, pregnant women, and patients with obesity or OSA.
Recovery and Discharge:
Supervised recovery in a designated area until predefined discharge criteria are met.
Patients discharged only when they demonstrate stable vital signs, return of airway reflexes, and orientation.
Provide written post-discharge care instructions and ensure patient escort by a responsible adult.
Documentation and Quality Assurance:
Maintain accurate records of sedation plans, medication dosages, monitoring data, and recovery details.
Regular audit and compliance with jurisdictional reporting requirements for sedation-related morbidity or mortality.
Key Principles
The goal of procedural sedation is to provide safe, effective care while avoiding complications related to unanticipated deep sedation.
Adherence to guidelines such as ANZCA PG09(G) ensures best practices for patient safety and procedural success.
GS_1.6 Discuss indications, contraindications and other patient, surgical and anaesthetic factors influencing choice of agents for: • Induction of anaesthesia • Maintenance of anaesthesia • Muscle relaxation and reversal • Management of postoperative nausea and vomiting • Pain management
Induction of Anaesthesia
Indications:
Rapid loss of consciousness for airway control and surgical preparation.
Agents selected based on speed of onset, hemodynamic stability, and patient-specific factors.
Contraindications:
Propofol: Caution in hemodynamic instability or allergy.
Etomidate: Avoid in adrenal insufficiency.
Ketamine: Avoid in patients with raised intracranial pressure (ICP) or severe cardiovascular disease.
Patient/Surgical/Anaesthetic Factors:
Hemodynamics: Choose etomidate or ketamine for unstable patients.
Airway status: Consider rapid-sequence induction for aspiration risk.
Comorbidities: Adjust agents for conditions like epilepsy, obesity, or pregnancy.
Maintenance of Anaesthesia
Indications:
Continuous sedation, amnesia, and immobility throughout surgery.
Contraindications:
Volatile agents (e.g., sevoflurane): Caution in malignant hyperthermia.
Intravenous agents: Avoid high-dose propofol in prolonged sedation (propofol infusion syndrome).
Patient/Surgical/Anaesthetic Factors:
Procedure duration: IV agents for short cases, volatile agents for longer cases.
Comorbidities: Adjust volatile agents for COPD or severe asthma.
Positioning: Optimize ventilation for prone or lateral positions.
Muscle Relaxation and Reversal
Indications:
Facilitation of tracheal intubation and surgical field optimization.
Contraindications:
Depolarizing agents (e.g., suxamethonium): Avoid in hyperkalemia, burns, or neuromuscular disorders.
Non-depolarizing agents: Caution in severe renal or hepatic impairment (e.g., vecuronium).
Patient/Surgical/Anaesthetic Factors:
Duration: Short-acting agents for brief procedures; long-acting for prolonged cases.
Reversal: Consider neostigmine or sugammadex based on agent and residual paralysis.
Management of Postoperative Nausea and Vomiting (PONV)
Indications:
Prevent PONV in high-risk patients using multimodal prophylaxis.
Contraindications:
5-HT3 antagonists: Caution in QT prolongation.
Steroids (e.g., dexamethasone): Avoid in poorly controlled diabetes or active infection.
Patient/Surgical/Anaesthetic Factors:
Risk factors: Female gender, non-smoking status, and volatile agents increase PONV risk.
Surgery type: Higher risk in laparoscopic or ENT procedures.
Pain Management
Indications:
Relieve acute postoperative pain and facilitate recovery.
Contraindications:
Opioids: Avoid in opioid-tolerant patients or those with respiratory depression risk.
NSAIDs: Contraindicated in renal failure, bleeding risk, or gastric ulcers.
Patient/Surgical/Anaesthetic Factors:
Pain severity: Tailor multimodal approaches combining opioids, NSAIDs, and regional techniques.
Surgical site: Regional anesthesia for specific areas (e.g., neuraxial blocks for lower limb surgery).
Comorbidities: Adjust for chronic pain, obesity, or substance use disorders.
This structured approach emphasizes balancing efficacy, safety, and patient needs to optimize anaesthetic care.
GS_1.7 Describe alterations to drug response in the following sub-groups: • Extremes of age • Pregnancy and lactation • Drug addiction • Opioid tolerance • Cardiac disease • Hepatic impairment • Renal impairment • Critically ill patients, including the trauma patient
Extremes of Age
Neonates and Infants:
Reduced metabolism and clearance due to immature hepatic and renal function.
Altered protein binding increases free drug concentrations.
Increased sensitivity to opioids and neuromuscular blockers due to immature receptor systems.
Elderly:
Reduced hepatic and renal function prolongs drug half-life.
Increased sensitivity to sedatives and opioids due to changes in receptor sensitivity.
Decreased plasma protein levels lead to higher active drug fractions.
Pregnancy and Lactation
Pregnancy:
Increased cardiac output and blood volume dilute drug concentrations.
Enhanced hepatic enzyme activity alters metabolism (e.g., increased clearance of propofol).
Reduced gastric emptying delays oral drug absorption.
Drugs cross the placenta; consider fetal safety (e.g., avoid teratogenic agents).
Lactation:
Lipophilic drugs can transfer into breast milk; assess risk-benefit for the neonate.
Drug Addiction
Altered Pharmacokinetics:
Chronic use of substances (e.g., alcohol, cocaine) induces hepatic enzymes, increasing metabolism of some drugs.
Altered Pharmacodynamics:
Desensitization or downregulation of receptors reduces efficacy (e.g., opioids).
Higher doses often required for effective anesthesia.
Opioid Tolerance
Reduced Analgesic Effect:
Tolerance develops due to receptor desensitization and downregulation.
Increased opioid doses or adjunctive agents (e.g., ketamine) often required.
Cross-Tolerance:
Partial tolerance to other opioids may occur.
Cardiac Disease
Reduced Cardiac Output:
Impaired drug delivery to the liver and kidneys reduces clearance.
Increased sensitivity to cardiovascular depressants (e.g., propofol, volatile agents).
Altered Volume of Distribution:
Fluid retention may dilute water-soluble drugs, reducing efficacy.
Hepatic Impairment
Reduced Drug Metabolism:
Decreased phase I reactions (e.g., oxidation, reduction); phase II usually preserved.
Prolonged half-life of hepatically metabolized drugs (e.g., midazolam, opioids).
Increased Drug Sensitivity:
Reduced protein binding elevates free drug levels.
Risk of hepatic encephalopathy with certain agents (e.g., benzodiazepines).
Renal Impairment
Reduced Clearance:
Accumulation of renally excreted drugs (e.g., morphine metabolites, aminoglycosides).
Prolonged duration of action and increased risk of toxicity.
Altered Drug Binding:
Uremic toxins displace drugs from protein binding sites, increasing free drug levels.
Critically Ill Patients, Including Trauma Patients
Hyperdynamic Circulation:
Enhanced drug clearance due to increased cardiac output.
Hypoperfusion:
Impaired hepatic and renal clearance in shock states.
Altered Volume of Distribution:
Fluid shifts (e.g., edema, third spacing) dilute hydrophilic drugs, requiring dose adjustments.
Inflammation and Organ Dysfunction:
Sepsis-induced alterations in drug metabolism and excretion.
Protein binding affected by hypoalbuminemia, increasing free drug levels.
Trauma-Specific Factors:
Hypovolemia and acidosis alter drug distribution and receptor activity.
Coagulopathy influences response to anticoagulants and reversal agents.
Tailoring drug selection and dosing to these sub-groups ensures safety and efficacy while minimizing adverse effects.
GS_1.9 Discuss the aetiology of and measures to prevent intra-operative awareness under general anaesthesia and methods to monitor depth of anaesthesia
Aetiology of Intraoperative Awareness
Intraoperative awareness occurs when a patient becomes conscious during surgery and may recall the event afterward. Common causes include:
1. Anaesthetic-Related Causes
Inadequate Drug Delivery:
Equipment malfunction (e.g., vaporizer failure, disconnection of intravenous lines).
Incorrect dosing of anaesthetic agents, particularly in high-risk cases.
Drug Tolerance or Resistance:
Chronic opioid or sedative use leading to higher anaesthetic requirements.
Genetic variability affecting drug metabolism or response.
2. Patient-Related Factors
High Risk for Awareness:
Emergency surgery (e.g., trauma, obstetrics) where rapid sequence induction limits time for anaesthesia onset.
Hemodynamic instability requiring reduced anaesthetic dosing.
Comorbidities:
Reduced cardiac output or shock states impairing drug distribution and effect.
Patients with obstructive sleep apnoea or obesity requiring altered dosing.
3. Surgical Factors
High-Stimulation Procedures:
Surgery with intense nociceptive stimuli (e.g., sternotomy, neurosurgery).
Minimal Anaesthetic Use:
Techniques requiring reduced anaesthetic depth (e.g., cardiac surgery with cardiopulmonary bypass).
Measures to Prevent Intraoperative Awareness
1. Preoperative Planning
Identify High-Risk Patients:
Review history for prior awareness, chronic pain syndromes, or substance use.
Individualize Anaesthetic Plan:
Adjust dosages based on patient comorbidities, weight, and surgical requirements.
2. Intraoperative Measures
Appropriate Dosing:
Ensure adequate induction with hypnotic agents.
Maintain sufficient maintenance anaesthesia with volatile agents, intravenous infusions, or balanced techniques.
Equipment Checks:
Verify proper functioning of vaporizers, infusion pumps, and monitoring devices before surgery.
Neuromuscular Blockade Awareness:
Avoid relying solely on patient immobility; combine with measures to ensure unconsciousness.
Prevention in Specific Cases:
Use high-dose opioids, benzodiazepines, or scopolamine for patients at risk of reduced anaesthetic dosing.
3. Postoperative Measures
Early Detection:
Conduct postoperative interviews to identify potential awareness experiences.
Support and Counselling:
Provide psychological support to minimize the risk of post-traumatic stress disorder (PTSD).
Methods to Monitor Depth of Anaesthesia
1. Clinical Monitoring
Hemodynamic Parameters:
Blood pressure and heart rate changes may indicate inadequate anaesthesia.
Movement:
Spontaneous or reflex movements can signal insufficient anaesthetic depth.
2. EEG-Based Monitors
Bispectral Index (BIS):
Calculates a numerical index (0-100) to estimate anaesthetic depth; <60 suggests adequate depth.
Entropy Monitoring:
Measures cortical and subcortical activity; lower values indicate deeper anaesthesia.
Patient State Index (PSI):
Derived from EEG to provide a measure of awareness likelihood.
3. Auditory Evoked Potentials (AEPs)
Middle Latency AEPs:
Reflect brainstem and cortical response to auditory stimuli; less commonly used but sensitive.
4. End-Tidal Agent Monitoring
End-Tidal Volatile Agent Concentration:
Ensures adequate volatile anaesthetic levels based on minimum alveolar concentration (MAC) values.
5. Neuromuscular Monitoring
Train-of-Four (TOF):
Ensures complete paralysis without relying on immobility for depth of anaesthesia assessment.
GS_1.12 Discuss the potential causes and management of failure to wake from anaesthesia
Potential Causes
1. Anaesthetic-Related Factors
Prolonged Drug Effect:
Overdose of volatile or intravenous anaesthetics.
Delayed clearance due to hepatic or renal impairment.
Prolonged neuromuscular blockade (e.g., inadequate reversal, pseudocholinesterase deficiency with suxamethonium).
Drug Interactions:
Potentiation of anaesthetic agents by pre-existing medications (e.g., opioids, benzodiazepines).
2. Patient-Related Factors
Neurological Issues:
Pre-existing conditions (e.g., dementia, cerebrovascular disease).
Acute events (e.g., stroke, hypoxic brain injury, seizure, raised intracranial pressure).
Metabolic Disorders:
Hypoglycemia or hyperglycemia.
Electrolyte imbalances (e.g., hyponatremia, hypercalcemia).
Hypothermia causing slowed drug metabolism and neurological depression.
Systemic Factors:
Hypoxia or hypercapnia.
Hemodynamic instability (e.g., hypotension, shock).
Sepsis or severe infection.
3. Surgical or Procedure-Related Factors
Prolonged surgery with high drug dosages.
Brain or spinal cord involvement in surgery (e.g., neurosurgical procedures).
Postoperative complications such as hemorrhage or edema.
4. Other Causes
Equipment malfunction (e.g., residual inhalational agents due to circuit failure).
Rare conditions like malignant hyperthermia or atypical drug metabolism.
Management
1. Immediate Assessment
Airway, Breathing, Circulation:
Ensure airway patency, adequate ventilation, and hemodynamic stability.
Check oxygenation (SpO₂, ABG) and ventilation (capnography).
Neurological Status:
Assess pupil size and reactivity, motor responses, and Glasgow Coma Scale (GCS).
Check for focal neurological signs indicating stroke or other acute events.
2. Investigations
Laboratory Tests:
Blood glucose, arterial blood gas (ABG), and electrolyte panel.
Renal and liver function tests.
Neuromuscular monitoring to exclude residual blockade (e.g., train-of-four ratio).
Imaging:
CT or MRI brain if neurological cause suspected.
3. Interventions
Reversal Agents:
Administer naloxone for opioid overdose or flumazenil for benzodiazepine sedation.
Administer sugammadex or neostigmine with glycopyrrolate for residual neuromuscular blockade.
Correct Metabolic Derangements:
Treat hypoglycemia with dextrose or electrolyte imbalances with appropriate replacements.
Rewarm hypothermic patients with forced-air warming systems.
Optimize Hemodynamics:
Treat hypotension with fluids or vasopressors.
Ensure adequate oxygen delivery.
4. Specialist Consultation
Involve neurologists, intensivists, or toxicologists if no immediate improvement.
Transfer to ICU for advanced monitoring and support if required.
5. Prevention
Optimize patient condition preoperatively, considering comorbidities and medication interactions.
Titrate anaesthetic agents appropriately, especially in high-risk populations.
Ensure proper neuromuscular monitoring and reversal at the end of surgery.
Vigilant monitoring in PACU to detect early signs of delayed recovery. "
GS_1.15 Discuss the management and postoperative follow up of a patient who reports intraoperative awareness under general anaesthesia
1. Immediate Management
Recognition and Support
Acknowledge the Report:
Treat the patient’s report seriously and without skepticism.
Provide Empathy and Reassurance:
Validate the patient’s experience and express genuine concern.
Initial Assessment
Obtain a Detailed History:
Explore the nature and timing of the awareness episode (e.g., hearing voices, pain, or feeling paralysis).
Exclude Other Causes:
Consider differential diagnoses such as delirium, ICU psychosis, or vivid dreams.
Document the Event
Comprehensive Documentation:
Record the patient’s account, including time, duration, and symptoms.
Report the Incident:
Notify the anaesthetic team and document in the patient’s notes for future reference.
2. Early Management
Debrief the Patient
Explanation of the Event:
Provide an understandable explanation of why awareness might have occurred, avoiding overly technical language.
Clarify Details:
Explain anaesthetic techniques used and whether mitigating factors (e.g., hemodynamic instability) contributed.
Psychological Support
Immediate Counselling:
Offer emotional support and acknowledge potential distress.
Referral to Specialist:
Arrange early access to psychological or psychiatric support if symptoms of distress are significant.
Review and Investigate
Root Cause Analysis:
Perform a structured review of the incident, including:
Anaesthetic record (drug dosages, end-tidal anaesthetic levels).
Equipment checks for malfunction.
Monitoring adequacy (e.g., depth of anaesthesia monitors, neuromuscular blockade).
Team Discussion:
Conduct a case review with the anaesthesia team to identify areas for improvement.
3. Postoperative Follow-Up
Short-Term Follow-Up
Psychological Assessment:
Screen for acute stress reactions, such as anxiety, insomnia, or flashbacks.
Information Provision:
Provide educational resources about intraoperative awareness to normalize the experience and reduce stigma.
Long-Term Follow-Up
Monitor for PTSD:
Be vigilant for symptoms such as hypervigilance, nightmares, or avoidance behaviors.
Refer to a psychologist or psychiatrist if PTSD develops.
Ongoing Communication:
Maintain regular contact with the patient to address concerns and ensure resolution of distress.
Anaesthetic Planning for Future Procedures
Record in Medical History:
Highlight the history of awareness for consideration in future anaesthetic planning.
Enhanced Anaesthetic Techniques:
Discuss options such as BIS monitoring, preoperative sedation, and amnestic agents for subsequent surgeries.
Preoperative Discussion:
Involve the patient in planning to build trust and reduce anxiety.
4. System-Level Considerations
Quality Improvement
Audit and Review:
Contribute findings to hospital-wide quality improvement initiatives.
Staff Education:
Train anaesthetists in recognizing and preventing intraoperative awareness.
Reporting
Incident Reporting System:
Report the event to relevant governing bodies (e.g., ANZCA, AAGA registry) for broader analysis and learning.
Summary
Management of intraoperative awareness requires immediate empathetic support, thorough investigation, and structured follow-up to address psychological sequelae and prevent recurrence. Early referral to psychological services and integration into quality improvement systems are essential for comprehensive care."
GS_1.16 Discuss the potential causes, prevention and management of postoperative delirium
Potential Causes
1. Patient-Related Factors
Age and Frailty:
Elderly patients are at higher risk due to reduced cognitive reserve.
Pre-existing Cognitive Impairment:
Dementia or mild cognitive impairment significantly increases risk.
Comorbidities:
Chronic illnesses, such as cardiovascular disease, diabetes, or depression.
Substance Use:
Alcohol use disorder or withdrawal.
Chronic use of benzodiazepines or opioids.
2. Surgery-Related Factors
Type of Surgery:
High-risk procedures (e.g., cardiac, orthopaedic, or major abdominal surgeries).
Duration of Surgery:
Prolonged operative time leading to increased stress and metabolic demand.
Perioperative Hypoxia or Hypotension:
Reduced cerebral perfusion and oxygenation.
3. Anaesthetic-Related Factors
Depth of Anaesthesia:
Both inadequate and excessive depth may contribute.
Specific Drugs:
Use of anticholinergics, benzodiazepines, or high doses of opioids.
Postoperative Pain Management:
Poorly controlled pain or excessive sedation.
4. Environmental Factors
Hospital Environment:
Sleep disruption, sensory deprivation, or overstimulation in ICU or ward.
Inadequate Postoperative Care:
Delayed mobilization or lack of routine cognitive assessments.
Prevention
1. Preoperative Strategies
Risk Identification:
Screen for risk factors using tools like the Confusion Assessment Method (CAM).
Optimize Comorbidities:
Stabilize chronic conditions and ensure appropriate medication use.
Patient Education:
Inform patients and families about potential delirium risk and warning signs.
2. Intraoperative Measures
Optimized Anaesthetic Techniques:
Use short-acting agents and avoid high doses of benzodiazepines or anticholinergics.
Employ BIS monitoring to maintain an appropriate depth of anaesthesia.
Ensure Physiological Stability:
Maintain normothermia, oxygenation, and hemodynamic stability.
3. Postoperative Interventions
Early Mobilization:
Encourage ambulation to reduce immobility-associated delirium.
Pain Control:
Provide multimodal analgesia to minimize opioid use.
Minimize Environmental Stressors:
Reduce noise and ensure adequate lighting to promote circadian rhythm.
Hydration and Nutrition:
Address dehydration and electrolyte imbalances promptly.
Management
1. Initial Assessment
Identify Delirium:
Use standardized tools like CAM or the 4AT to confirm diagnosis.
Evaluate Underlying Causes:
Conduct a thorough review of patient history, medications, and recent events.
2. Treat Underlying Causes
Metabolic and Physiological Factors:
Correct hypoxia, hypotension, hypoglycemia, or electrolyte imbalances.
Infections:
Treat sepsis or localized infections with appropriate antibiotics.
Medications:
Discontinue or adjust potentially causative drugs (e.g., benzodiazepines, anticholinergics).
3. Non-Pharmacological Management
Reorientation:
Engage patients in frequent reorientation activities (e.g., clocks, calendars).
Optimize Environment:
Promote sleep hygiene and provide hearing aids or glasses if needed.
Family Involvement:
Encourage familiar interactions to reduce distress.
4. Pharmacological Management (if necessary)
Indications:
Severe agitation posing risk to self or others, or unresponsive to non-pharmacological measures.
Medications:
Haloperidol or atypical antipsychotics (e.g., olanzapine, quetiapine) in low doses.
Avoid benzodiazepines unless delirium is due to alcohol or benzodiazepine withdrawal.
Follow-Up
Post-Discharge Care:
Monitor for persistent cognitive deficits and refer for geriatric or psychiatric evaluation if needed.
Prevent Recurrence:
Address modifiable risk factors and educate caregivers about delirium prevention.
Summary
Postoperative delirium arises from a combination of patient, surgical, and environmental factors. Prevention involves optimizing preoperative, intraoperative, and postoperative care, with a focus on minimizing risk factors. Management prioritizes addressing underlying causes, employing non-pharmacological strategies, and using pharmacological interventions only when necessary."
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