course material
General Anesthesia
Course
General Anesthesia
General anesthetics have been performed since 1846 when Morton demonstrated the first anesthetic (using ether) in Boston, USA.
Local anesthetics arrived later, the first being scientifically described in1884.
General anesthesia is described as a reversible state of unconsciousness with inability to respond to a standardized surgical stimulus.
In modern anesthetic practice this involves the triad of: unconsciousness, analgesia, muscle relaxation.
Content:
- Assessment
- Planning I: Monitors
- Planning II: Drugs
- Planning III: Fluids
- Planning IV: Airway
Management - Induction
- Maintenance
- Emergence
- Postoperative
Objectives of anesthesia - Unconsciousness
- Amnesia
- Analgesia
- Oxygenation
- Ventilation
- Homeostasis
- Airway Management
- Reflex Management
- Muscle Relaxation
- Monitoring
- Role Of Anesthetists
- Preoperative evaluation and patient preparation
- Intraoperative management
- General anesthesia
Inhalation anesthesia
Total IV anesthesia
- Regional anesthesia & pain management
Spinal, epidural & caudal blocks
Peripheral never blocks
Pain management (acute and chronic pain) - Postanesthesia care (PACU management)
- Anesthesia complication & management
- Case study
Preoperative anesthetic evaluation
Risks of Anesthesia - Physical status classification
- Class I:A normal healthy patients
- Class II: A patient with mild systemic disease (no functional
limitation) - Class III: A patient with severe systemic disease (some
- functional limitation)
- Class IV: A patient with severe systemic disease that is a
constant threat to life (functionality incapacitated) - Class V:A moribund patient who is not expected to survive
without the operation - Class VI: A brain-dead patient whose organs are being
removed for donor purposes - Class E: Emergent procedure
Anesthetic Plan
Premed
Intraoperative Postoperative
management management
General Monitoring Pain control
PONV
Airway management Positioning Complications
Induction Fluid management postop ventilation
Maintenance Special techniques Hemodynanic monit
Muscle relaxation
NPO Status - NPO, Nil Per Os, means nothing by mouth
- Solid food: 8 hrs before induction
- Liquid: 4 hrs before induction
- Clear water: 2 hrs before induction
- Pediatrics: stop breast milk feeding 4 hrs
before induction - General Anesthesia
- Monitor
- Preoxygenation
- Induction ( including RSI & cricoid pressure)
- Muscle relaxants
- Mask ventilation
- Intubation & ETT position comfirmation
- Maintenance
- Emergence
Airway exam
Mallampati classification
Class I:
uvula, faucial pillars, soft palate visible
Class II:
faucial pillars, soft pillars visible
Class III:
soft and hard palate visible
Class IV:
hard palate visible
- Induction agents
- Opioids – fentanyl
- Propofol, Thiopental and Etomidate
Muscle relaxants: - Depolarizing
- < >IV induction
- Inhalation induction
General Anesthesia - Reversible loss of consciousness
- Analgesia
- Amnesia
- Some degree of muscle relaxation
Intraoperative management - Maintenance
Inhalation agents: N2O, Sevo, Deso, Iso
Total IV agents: Propofol
Opioids: Fentanyl, Morphine
Muscle relaxants
Balance anesthesia
- Monitoring
- Position – supine, lateral, prone, sitting, Litho
- Fluid management
- Crystalloid vs colloid
- NPO fluid replacement: 1st 10kg weight-
4ml/kg/hr, 2nd 10kg weight-2ml/kg/hr and
1ml/kg/hr thereafter
- Intraoperative fluid replacement: minor
procedures 1-3ml/kg/hr, major procedures 4-
6ml/kg/hr, major abdominal procedures 7-10/kg/ml
Emergence
- Turn off the agent (inhalation or IV agents)
- Reverse the muscle relaxants
- Return to spontaneous ventilation with adequate ventilation and oxygenation
- Suction upper airway
- Wait for pts to wake up and follow command
- Hemodynamically stable
- Postoperative management
- Post-anesthesia care unit (PACU)
- Oxygen supplement
- Pain control
- Nausea and vomiting
- Hypertension and hypotension
- Agitation - Surgical intensive care unit (SICU)
- Mechanical ventilation
- Hemodynamic monitoring
- General Anesthesia
Complications and Management - Respiratory complication
- Aspiration – airway obstruction and pneumonia
- Bronchospasm
- Atelectasis
- Hypoventilation - Cardiovascular complication
- Hypertension and hypotension
- Arrhythmia
- Myocardial ischemia and infarction
- Cardiac arrest
- General Anesthesia
Complication and Management - Neurological complication
- Slow wake-up
- Stroke - Malignant hyperthermia
-
Case Report
Arterial oxygen desaturation following PCNL
The Patient - Patient : 73 y/o Female
BW 68 kg, BH 145 cm (BMI 32) - Chief complaint :
Right flank pain (stabbing, frequent attacks)
General malaise and fatigue - Past history : Hypertension under regular control
Senile dementia (mild)
- Preoperative diagnosis : Right renal stone (3.2 cm)
- Operation planned : Right PCNL (percutaneous nephrolithotomy)
Preanesthesia Assessment - EKG : Normal sinus rhythm
- CXR : Borderline cardiomegaly & tortuous aorta
- Lab data : Hb 10.5 / Hct 33.2
BUN 24 / Creatinine 1.1
GOT 14
PT, aPTT WNL
Anesthetic Technique - General anesthesia with endotracheal intubation
- Standard monitoring apparatus for ETGA
- Induction : Fentanyl ug/kg
propofol 2mg/kg
Succinylcholine 80 mg
Atracurium 25 mg - Endotracheal tube (ID 7.0-mm) @ 19cm
-
Intra-operative Events Maintenance: Isoflurane 2~3% in O2 0.5 L/min
- Position: prone
- Blood loss : 300 mL → PRBC 2U
Intra-operative Events - Stable hemodynamics
- Abnormal findings 30 minutes after surgery started
Increased airway pressure 35~40 mmHg
SpO2 dropped to 90~95% - Bilateral breathing sounds were still audible then
- Management : Solu-cortef 100 mg IV stat
Aminophylline 250 mg IV drip
Bricanyl 5 mg inhalation
ABG
PH 7.2
PaO2 90.5
PaCO2 66.8
HCO3 26
Postoperative - The patient’s condition was kept up until the end of surgery
- SpO2 90~92% after the patient was placed in the supine position
again with diminished breathing sound over right lower lung - The patient was transferred to SICU for further care (*)
- Chest X-ray was followed in SICU
Postoperative Course - Pigtail drainage in SICU
- Pleural effusion : bloody
RBC numerous
WBC 7800 (Seg 94%)
Gram stain (-) - Impression : Right hydrothorax and hemothorax
- Extubation and transfer to ordinary ward
- Pigtail removed