Ketamine Anesthesia

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Ketamine Anesthesia
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Introduction

• Ketamine Total intravenous anesthetic
• Produces dissociative anesthesia Patient is
  unconscious and amnesic and deeply analgesic
• Relatively safe drug but needs to be used with
  caution
• Ketamine can be used as sole anesthetic agent
  without muscle relaxation
• Can also be used with muscle relaxants when needed

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Indications

• For short procedures of less than 60 minutes
• Repair of perineal tears
• Extensive cervical tears
• Manual removal of placenta
• Cesarean section
• Breast abscess drainage
• As backup anesthesia if general anesthesia
  inhalation apparatus fails or general anesthesia
  used without inhalation apparatus

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Precautions

• Causes hallucinations when used alone
• Avoid using in psychotic women
• Diazepam 10 mg IV helps in reducing
  hallucinations
• No muscular relaxation, so big incision in
  cesarean section
• Should not be used in women with elevated blood
  pressure Pre-eclampsia, eclampsia and heart
  disease
• Increases intra-cranial pressure

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Benefits

• Pharyngeal and laryngeal reflexes are usually
  intact Patient can breathe on her own
• Good ventilatory response Increased respiration
  rate and tidal volumeoxygenation is maintained
• Increases the heart rate and blood pressure
  Useful for patients in shock
• Less postoperative nausea and vomiting with
  ketamine this is a major disadvantage with other
  anesthetic agents

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Limitations

• Emergence reaction Hallucinations after patient
  recovers from anesthesia can be minimized by
  giving 10 mg diazepam IV at the time of induction
  or after the baby has been born when used for
  lower segment cesarean section
• Salivation common in children and adults can be
  prevented by giving atropine as premedication
• Saliva in children can touch the vocal cords
  leading to laryngeal spasm, which is a serious
  complication

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Limitations (contd)

• Apnea relatively rare occurrence with ketamine
  can minimize risk by giving slow IV injection
• Tachycardia and hypertension disadvantage in
  hypertensive patients and those with
  pre-eclampsia
• No muscle relaxation operations on the abdomen
  more difficult
• Cesarean section will need larger incision

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Presentation

• Supplied as clear liquid in multidose vials
• Ketamine 10 mg/mL is preservative-free
• 50 mg/mL and 100 mg/mL with preservatives
• Store in refrigerator after the vial has been
  opened

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Incompatibility

• Mixing with other drugs like diazepam produces a
  thick paste do not mix them in syringe
• Do not inject them one after another through a
  cannula, unless a drip is running
• Flush cannula with normal saline before giving
  the second drug

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Dosage and Administration

• Can be given IM, IV or by infusion
• Variable dosage
• 610 mg/kg body weight IM produces surgical
  anesthesia within 10 minutes and lasts for 30
  minutes
• 2 mg/kg body weight given slowly IV over 5
  seconds, lasts for about 15 minutes
• 0.25 mg/kg body weight for maintenance of
  anesthesia
• Infusion of ketamine suitable for cesarean
  section after the delivery of the baby

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Ketamine for Cesarean Section

• Used when facility for general anesthesia with
  endotracheal intubation not available
• When spinal anesthesia is contraindicated
• Emergency situations where one cannot wait for
  spinal anesthetic
• Ketamine is given as a bolus of 2 mg/kg body
  weight IV slowly, over 5 seconds for induction
  of anesthesia

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Ketamine for Cesarean Section (contd)

• Dose of 0.25 mg/kg boluses repeated if necessary
  before delivery of baby
• Infusion of ketamine started after delivery to
  reduce neonatal depression
• Slow IV diazepam 510 mg after delivery of baby
  decreases dose of ketamine needed and reduces
  emergence reactions

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Some Points to Remember

• Patients may keep their eyes open even with
  sufficient depth of anesthesia
• Nystagmus may be present
• Fast respiratory rate is not a sign of light
  anesthesia
• Purposeful movement is a sign for repeat dose
• Patients airway can obstruct during ketamine
  anesthesia
• Monitor airway patency either with bag and mask
  or by feeling the breath of the patients on your
  skin

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Premedication for Short Procedures

• Antacid Sodium Citrate 30 mL before inducing
  anesthesia
• Atropine 0.5 mg
• Diazepam 510 mg (for cesarean after delivery
  of baby)
• Oxygen by mask

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Preparation for Short Procedures

• Make sure that patient can be easily monitored
• Ensure that all equipment and drugs needed are
  easily accessible
• All necessary drugs are accessible
• Suction machine ready
• Bag and mask ready
• Be ready for intubation if required
• Be prepared to extend the anesthesia if needed
• Have an IV cannula inserted before induction a
  simple butterfly cannula will be adequate

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Preparation for Short Procedures (contd)

• Surgeon must be scrubbed
• Assistant should be available, if required
• Surgical instruments should be opened
• Premedicate all patientsorally or IV on
  induction
• Remember This is a short procedure, there is no
  time to lose anesthesia should be used for the
  procedure, not for other activities

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Induction Short Procedures

• Check womans vital signs Temperature, pulse,
  blood pressure, respiration rate
• Induction of anesthesia 2 mg/kg body weight of
  ketamine IV slowly over 5 seconds
• Small women may need only 50 mg
• Adequate anesthesia is provided for 15 minutes

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Induction and Maintenance for Long Procedures

• Preparation and induction same as for short
  procedures
• For long procedures
• Start infusion of ketamine 200 mg in 500 mL
  dextrose/saline at 3 mg/kg/hr (75130 drops
  depending on the weight of the woman)
• Check level of anesthesia
• Continue to monitor the patient throughout the
  procedure

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Induction and Maintenance for Long Procedures

• Blood pressure and heart rate will go up
• Patients may phonate may not be due to light
  anesthesia
• Purposeful movements are signs of light anesthesia