Lecture Title : General Anesthesia

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Lecture Title General Anesthesia

• Lecturer name
• Lecture Date

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Lecture Objectives.. Students at the end of the
lecture will be able to

• Define general Anaesthesia
• Learn about several agents used on induction of
  general anaesthesia including intravenous agents,
  inhalation agents, neuromuscular blocking agents
  and reversal agents.
• Understand basic advantages and disadvantages of
  these agents.
• Complications commonly encountered during general
  anaesthesia

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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.
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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.
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Anesthetic plan

• A good anesthetic begins with a good plan.
• There is no rigid format for planning anesthesia.
  
• Each plan is adapted to each case.
• The fundamental goal of anesthetic management is
• to provide safety,
• comfort and convenience, first for the patient
  and second for those caring for the patient.

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Anesthetic plan

• After a good plan, a good preparation is required
  for a good anesthetic.
•  Before every anesthetic, every anesthesiologist
  should go through a checklist of necessary items
  including,
• anesthesia machine,
• ventilator,
• oxygen and nitrous supply check,
• suction device,
• monitors and anesthesia cart.  

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Anesthetic plan

• Before bringing the patient to the operating
  room,
• the proper verification of patient's identity,
• the planned procedure and
• the site of the procedure should be carried out
  by the anesthesiologist.
• All the preparations should be completed before
  the patient enters the room including the
  placement of a working peripheral intravenous
  line.

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Anesthetic plan

• The primary goals of general anesthesia are
• to maintain the health and safety of the patient
  while providing amnesia, hypnosis (lack of
  awareness), analgesia, and optimal surgical
  conditions (e.g., immobility).
• Preoperative planning involves
• the integration of pre-,
• intra-, and
• postoperative care.
• Flexibility is an essential
• multiple approaches to
• induction,
• maintenance, and
• emergence should be considered.

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Anesthetic plan

• Preoperative planning involves the integration
  of
• pre-,
• intra-, and
• postoperative care.
• Flexibility is an essential
• Multiple approaches to
• induction,
• maintenance, and
• emergence should be considered.

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Anesthetic plan

• The plan should include the following
• A premedication.
• Need standard ASA monitors. However, if the
  patient may experience large hemodynamic
  fluctuations, invasive monitoring should be
  considered (e.g., central venous pressure for
  volume monitoring, arterial line for potential
  hemodynamic instability).
• A review of anesthetic options general
  anesthesia, regional anesthesia, and combinations
  thereof should be reviewed and options
  appropriate for the patient listed in the final
  assessment.
• Plan for postoperative pain control.

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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

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Premedication

• Guidelines for prophylaxis for pulmonary
  aspiration
• Histamine (H2) antagonists
• Cimetidine (Tagamet), ranitidine (Zantac),
  significantly reduce the volume and the acidity
  of gastric secretions.
• Metoclopramide (Reglan) enhances gastric emptying
• Midazolam (Versed) provides excellent amnesia and
  sedation.
• Lorazepam (Ativan) may also be used but can cause
  more prolonged amnesia and postoperative
  sedation. It should not be given intramuscularly.
• Opioids are not usually given as premedication
  unless the patient has significant pain

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THE MONITORS

• Standard ASA monitoring -
• Oxygenation (oxygen analyzer, pulse oximetry)
• Ventilation (capnography, minute ventilation),
  respiratory rate (under regional anesthesia)
• Circulation (electrocardiogram ECG, arterial
  blood pressure, perfusion assessment),
• Temperature.

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General Anesthesia

• Monitor
• Preoxygenation
• Induction ( including RSI cricoid pressure)
• Muscle relaxants
• Mask ventilation
• Intubation ETT position comfirmation
• Maintenance
• Emergence

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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
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Sniffing position
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Mask and airway tools
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Mask ventilation and intubation
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Oral and nasal airway
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Intubation
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Intubation
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Laryngeal view
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Laryngeal view scoring system
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Difficult airway
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Fiberoptic scope intubation
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Trachea view Carina view
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Glidescope
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Fast track LMA
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LMA
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Induction agents

• Opioids fentanyl
• Propofol, Thiopental and Etomidate
• Muscle relaxants
• Depolarizing
• Nondepolarizing

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Induction

• IV induction
• Inhalation induction

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General Anesthesia

• Reversible loss of consciousness
• Analgesia
• Amnesia
• Some degree of muscle relaxation

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Intraoperative management

• Maintenance
• Inhalation agents N2O, Sevo, Deso, Iso
• Total IV agents Propofol
• Opioids Fentanyl, Morphine
• Muscle relaxants
• Balance anesthesia

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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

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Intraoperative management 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

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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

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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

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General Anesthesia Complication and Management

• Neurological complication
• - Slow wake-up
• - Stroke
• Malignant hyperthermia

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Case Report Arterial oxygen desaturation
following PCNL

• ????????? ???

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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

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The Patient

• Past history Hypertension under regular
  control
• Senile dementia (mild)
• Preoperative diagnosis Right renal stone (3.2
  cm)
• Operation planned Right PCNL (percutaneous
  nephrolithotomy)

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Pre-anesthetic 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

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Preop
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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) _at_ 19cm
• Maintenance Isoflurane 23 in O2 0.5 L/min
• Position prone
• Blood loss 300 mL ? PRBC 2U

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Intra-operative Events

• Stable hemodynamics
• Abnormal findings 30 minutes after surgery
  started
• Increased airway pressure 3540 mmHg
• SpO2 dropped to 9095
• Bilateral breathing sounds were still audible
  then
• Management Solu-cortef 100 mg IV stat
• Aminophylline 250 mg IV
  drip
• Bricanyl 5 mg inhalation

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Intra-operative Events
pH 7.2
PaO2 90.5
PaCO2 66.8
HCO3- 26.0
BE -2.4
Na 143.0
K 4.0
Ca2 1.1
Hb/Hct 11.4/36.1

• ABG data

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Post-operative Course

• The patients condition was kept up until the
  end of surgery
• SpO2 9092 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

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Immed. Postop
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Preop
Immed. Postop
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Postoperative Course

• Pigtail drainage in SICU
• Pleural effusion bloody
• RBC numerous
• WBC 7800 (Seg 94)
• Gram stain (-)
• Impression Right hydrothorax and hemothorax

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s/p pigtail
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s/p pigtail
Immed. Postop
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Postoperative Course

• Extubation and transfer to ordinary ward
• Pigtail removed

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Reference book and the relevant page numbers..
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Thank You ?

• Dr.
• Date