Clinical Anesthesia Part II JUNYI LI, MD lijunyiutmb@yahoo.com April 2, 2009

Clinical Anesthesia

Part II

JUNYI LI, MD

lijunyiutmb@yahoo.com

April 2, 2009

Practice of anesthesiology

• Practice of anesthesiology is the practice medicine

• Preoperative evaluation

• Intraoperative management

• Postoperative care

• Anesthesiology is perioperative medicine

Practice of anesthesiology• 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

• History 1. Current problem 2. Other known problem 3. Medication history: allergies, drug intolerances, present therapy, alcohol, tobacco 4. Previous anesthetics, operations 5. Family history of anesthesia 6. Review of organ systems 7. Last oral intake• Physical examination: VS, airway, CV, lung, neuro• Lab evaluation, chest X-ray, ECG• ASA classification

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 planPremed Type of Intraoperative Postoperativeanesthesia management managementGeneral Monitoring Pain control Airway management Positioning Intensive care Induction Fluid management postop ventilation Maintenance Special techniques Hemodynanic monit Muscle relaxation

Regional Technique Agents

Monitored anesthesia care Supplement oxygen Sedation

Preoperative management

• Diabetes: hyperglycemia or hypoglycemia• Hypertension• Renal failure: HD patients – potassium level • Asthmatic patients• Chronic steroid use• Pregnant test• Preop medication: Sedation-benzodiazepine Aspiration precaution-H2 blockers, metoclopramide Antibiotics

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 examMallampati 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

Sniffing position

Mask and airway tools

Mask ventilation and intubation

Oral and nasal airway

Intubation

Intubation

Laryngeal view

Laryngeal view scoring system

Difficult airway

Fiberoptic scope intubation

Trachea view Carina view

Glidescope

Fast track LMA

LMA

Difficult Airway Algorithm

Induction agents

• Opioids – fentanyl

• Propofol, Thiopental and Etomidate

• Muscle relaxants:

Depolarizing

Nondepolarizing

Induction

• IV induction

• Inhalation induction

• Rapid sequence 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

Intraoperative management

• 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

Intraoperative managementEmergence

• 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 Complication 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 AnesthesiaComplication and Management

• Neurological complication - Slow wake-up

- Stroke

• Malignant hyperthermia

Regional Anesthesia

• No absolute indication for spinal or epidural anesthesia

• May improve outcome in selected situations• Blunt stress response to surgical stimulation• Decrease intraoperative blood loss• Lower the incidence of postoperative

thromboembolic events• Decrease M&M in high risk patients• Extend analgesia into postoperative period

Posterior and lateral view of spinal column

Spinal cord terminates

Human sensory dermatomes

Spinal anesthesia

• Patient position• Approachs: Midline & Paramedian• Technique• Monitoring during spinal anesthesia• Single dose spinal anesthesia• Continuous spinal anesthesia• Complications• Contraindications• Common local anesthetics for spinal anesthesia Lidocaine, Bupivacaine, Tetracaine, Ropivacaine

Physiology of Spinal Anesthesia

• LA blocks conduction of impulses along all with which it contacts

• Autonomic and pain fibers block - early

• Motor fibers block - late

Position

• Sitting position Sit straight first Chin on chest Arms resting on knees Footstool/table to support feet

Back curving like banana or shrimp • Lateral position Shoulders perpendicular to bed Positioned with hips on edge of bed Knee chest position and back curving

Approach

• Median approach• Most common

• Needle or introducer is placed midline

• Perpendicular to spinous processes

• Slightly cephalad

• Paramedian approach• For pts who cannot adequately flex

• Needle placed laterally(1.5cm) and slightly caudad to center

• Needle aimed medially and slightly cephalad

Midline approach to subarachnoid space

Technique

• Anatomic landmark identified• Superior iliac crests at L4 level• Spine is palpated• A sterile field estabolished• Skin wheel with LA• Introducer inserted and spinal needle passed• CSF presence• LA injection

Procedure

Monitoring

• Respiration

• Heart rate

• Blood pressure

LA & Concentration T10 level T4 level Duration Duration upper abd lower abd plain with epiBupivacaine 0.75% 12-14mg 12-18mg 90-120min 100-150min

Tetracaine 1% 10-12mg 10-16mg 90-120min 120-240min

Lidocaine 5% 50-75mg 75-100mg 60-75min 60-90min

Ropivacaine 02-1% 12-16mg 16-18mg 90-120min 90-120min

Common local anesthetics

Factors affecting spread of LA solution

• Baricity of LA solution

• Position of patient

• Concentration volume injected

• Level of injection

• Speed of injection

Assessing the level of block

Complications

• Common complications Postdural punture headache

Transient radicular syndrome

Backache

Hypotension

Itching

Complications

• Less common complications Cauda equina syndrome Total spinal Urinary retention Cardiac arrest Spinal/epidural hematoma Aseptic meningitis Bacterial meningitis Cranial nerve palsies

Contraindications

• Relative contraindications Hypovolemia

Preexisting neurologic disorders

Chronic back pain

Localized infection peripheral to regional site

Patients taking ASA, NSAID, dipyridamole

Contraindications

• Absolute contraindications Patient refusal

Infection at puncture site

Generalized sepsis

Severe coagulation abnormalities

Raised ICP

Epidural Anesthesia• Position• Approach: midline & paramedian• Location: cervical, thoracic, lumbar• Technique• Monitoring• Single dose - pain management• Continuous epidural - anesthesia & analgesia• Complication• Contraindication• Common LA for epidural anesthesia & analgesia Bupivacaine and ropivacaine

Epidural Approach

Epidural Anesthesia Kit

Loss of resistance technique

Epidural Catheter Placement

Epidural Catheter Placement

Epidural Catheter placement

Epidural Catheter Placement

Complications• Similar to spinal anesthesia

• Wet tap – postpuncture headache

• Total spinal anesthesia – apnea, hypotension, bradycardia

Common LA for Epidural Anesthesia• Bupivacaine: 0.125-0.25% for analgesia

0.5% for anesthesia

• Ropivacaine: 0.2% for analgesia

0.5-1% for anethesia

• Lidocaine: 2% for anesthesia

Caudal Anesthesia

• Common regional technique in pediatric pts

• Caudal space is sacral portion of epidural space

• Needle penetration of sacrococcygeal ligament from sacral hiatus

• Caudal anesthesia technique is difficult or impossible due to calcification of sacrococcygeal ligament

Caudal Technique

Caudal Anesthesia

Peripheral Nerve Block

• Injection of LA near the nerves to block sensation and motor function

• Can be used as primary and sole anesthetic technique for selective surgery

• Can be used for postop pain control

Common Nerve Block

• Brachial plexus block - Interscalene approach

- Axillary approach

- Infroclavicular approach

• Intravenous regional anesthesia (Bier block)• Lumbar plexus block - Femoral block

• Sacral plexus block - Sciatic nerve block

Anatomy of Brachial Plexus

Brachial Plexus Block-Interscalene Approach

Lumbar and Sacral Plexus Distribution

Femoral and Sciatic Nerve block

Peripheral Nerve Block

• Complications: - Intravascular injection and toxicity

- Chronic paresthesias and nerve damage

- Respiratory failure due to phrenic nerve block

- Others: infection, bleeding, allergic reaction

- The greatest immediate risk is systemic toxicity

from inadvertent intravascular injection

Local Anesthetic Toxicity

Peripheral Nerve Block

• Contraindications: - Uncooperative patient

- Coagulopathy

- Local skin infection

- Peripheral neuropathy

- Local anesthetic toxicity

Pain Management

• Most common symptom that brings patients to see a physician

• Pain is “an pleasant sensory and emotional experience associated with actual or potential tissue damage” (IASP)

• Component of anesthesia practice outside OR • “Nociception” (latin for harm or injury) is

used to describe the neural response only to traumatic or noxious stimuli

Pain Management• Classification: Persistent time: acute and chronic pain

Pathophysiology: nociceptive and neuropathic pain

Etiology: postoperative, cancer pain

Affected area: headache, low back pain

Presentation: local, radiate, diffuse

Characteristic: burning,sting,blunt,distended,angina

Pain Evaluation

(VRS)

Pain Management

• Medicine for Acute pain: NSAIDS: Ibuprofen, Ketorolac, Naproxen

Opioids: Morphine, Fentanyl, Meperidine,

Hydromorphone

Local anesthetics: Lidocaine, Bupivacaine,

Ropivacaine

Pain Management

• Administration route of pain medicine: - Oral - opioids, NSAIDs

- IV - single dose IV push or PCA(opioids, NSAIDs)

- IM - injection (opioids, NSAIDs)

- Local infiltration with LA

- Peripheral nerve block - intercostal, intrapleural

- Epidural - continuous or PCA with opioids, LA

- Intraspinal route with opioids

Pain Management - Chronic Pain

• Psychological and behavioral factors play a major role in chronic pain

• Psychology, neurosurgery consultation• Antidepression • Treatment of insomnia• Muscle relaxant • Oral NSAIDs and/or opioids• Neural blockade - somatic, sympathetic blocks• Radiofrequency ablation & cryoneurolysis• Spinal cord stimulation• Intraspinal pump for opioids and/or NSAIDs• Physical therapy: acupuncture

Case Study

• 73 years old male presents for 6 cm AAA repair

• PMH: CAD, HTN, DM

• PSH: CABG, appendectomy

• Social Hx: smoke 1ppd for 50 years

• Current Med: Nitro patch, ASA, lisinopril, clonidine, glucophage

Case Study

• Preop evaluation:

- Current medical problems: CAD, HTN, DM,

long term smoke

- Past anesthesia history

- Preop test: ECG, CXR, cardiac function,

pulmonary function

- Preop lab: CBC, Chemistry, coagulation

Case Study

• Preop evaluation:

- Airway exam

- NPO

- Home med on the day of operation

- Blood glucose on the day of operation

- Premedication

- Blood products

Case Study

• Intraoperative management:

- Monitor:

Noninvasive: ECG, pulse O2 saturation, BP

Invasive: A-line, CVP, PAC

Urine output

- Induction and intubation

- Fluid management

Case Study

• Intraoperative management: - Aortic clamp increases afterload, significantly increases BP, may cause myocardia ischemia and heart failure, vasodilator may needed - Kidney protection: furosemide, mannitol - Aortic clamp release decreases afterload, significantly decreases BP, vasoconstrictor, calcium usually are used

Case Study

• Postoperative care:

- Postop ventilation:

Ventilator setting

Weaning from ventilator

- Hemodynamic monitor

- Lab: H/H, electrolytes, coagulation

Case Study

• Complication:

- Bleeding: intra & postoperative

surgical & nonsurgical

- Cardiac complication

- Respiratory failure

- Renal insufficency