Regional and General Anesthesia for the Tropics David E. Byer, M.D. Assistant Professor of Anesthesiology Mayo Clinic College of Medicine
CONTRASTS Mayo Clinic Macha Hospital
CONTRASTS Road to Mayo Road to Macha
CONTRASTS Mayo Anesthesia Macha Anesthesia
Come with me to Macha Hospital! Problems with anesthesia Patients we may encounter The unique properties of ketamine The use of ketamine in various circumstances The use of spinal anesthesia
OUR FIRST PATIENT A 22-year-old man has been admitted with a gunshot wound to the abdomen. He is shocked from major internal bleeding and requires a laparotomy. We have only a very small supply of inotropes and want to try not to use them. What will you do for induction and maintenance of anesthesia?
OUR SECOND PATIENT A 2-year-old boy needs repair of his hernia. He is extremely frightened of the hospital and its staff. You think that obtaining intravenous access will be very difficult and that an inhalation induction will be difficult as well. How will you anesthetize this child?
OUR THIRD PATIENT A 37-year-old woman is recovering from 45% burns; she needs dressing changes every two days which are very painful. She has very few sites left for IV access and we don’t want to use them as she has further surgery to come. She is very scared of needles. How will you manage the sedation she requires for her dressing changes?
OUR FIRST PATIENT Our laparotomy patient (gunshot wound) is back on the ward. He has severe postoperative pain but we have been unable to get any morphine this month. How can we manage his postoperative pain?
OUR FOURTH PATIENT An 18-year-old girl has been admitted with severe asthma. You have been asked to see her as she has not improved with subcutaneous injections of salbutamol or intravenous aminophylline. She is getting tired and her oxygen saturation is falling. Can you do anything to help?
Ketamine The only anesthetic available which is Analgesic Hypnotic Amnesic Ketamine may be given IM, IV, or orally An anesthetic machine is not required for administration Resuscitation equipment needs to be at hand
Ketamine Available in three different concentrations 10mg/ml 50mg/ml 100mg/ml
Ketamine: the respiratory system The airway is usually well maintained with protective reflexes preserved. Respiration is well maintained if ketamine injected slowly Ketamine is an effective bronchodilator
Ketamine: the cardiovascular system There is an increase in both blood pressure and heart rate, reaching a maximum about two minutes after IV injection. There may be a wide variation in individual response A large rise in blood pressure usually responds to doses of IV diazepam
Ketamine: central nervous system Ketamine produces dissociative anesthesia (detachment from surroundings). Unlike other anesthetics patients may have their eyes open and may make reflex movements during the operation. Ketamine has a slower onset of action after intravenous injection (1-5 minutes) compared to other intravenous anesthetics
Ketamine: central nervous system Ketamine provides very good analgesia Upon recovery the patient may be agitated due to hallucination. Reduce by premedication with benzodiazepines (diazepam 0.2mg/kg orally one hour before, or 0.1mg/kg IV) or by decreased ketamine dosing Ketamine increases intracranial pressure: avoid when possible in recent head injury
Ketamine: GI system Ketamine increases salivation. This may lead to airway problems. Be prepared to suction Reduce salivation with atropine as a premed (10-20mcgm/kg) IM 30 minutes before, or at the time of induction (10mcg/kg) IV
Routes of administration Intravenous administration: induction dose (0.5-2mg/kg), maintenance (0.5mg/kg) for anesthesia Intramuscular administration: induction dose (5-10mg/kg), maintenance (3-5mg/kg) for anesthesia Oral administration sedation:(5-10mg/kg) for a child to a max of 500 mg for an adult
IV ketamine for induction and maintenance (gunshot wound) Ketamine ideal due to its cardiovascular effects of raising the blood pressure and heart rate. IV induction with ketamine (0.5-2mg/kg), atropine (10-20mcg/kg) and diazepam (0.1mg/kg) Endotracheal intubation could be helpful! Maintain with intermittent boluses ketamine (0.5mg/kg) or ketamine infusion: ketamine 500 mg in 500ml bag of fluid. Run at (2-4mg/kg/hr) stop infusion 20 min before end of surgery
IM ketamine (child hernia repair) Induce anesthesia with IM ketamine (5-10mg/kg), atropine (20mcg/kg), diazepam (0.1mg/kg) OR Sedate with IM ketamine (2mg/kg), atropine (20mcg/kg), diazepam (0.1mg/kg) to start an intravenous line If IV access impossible, maintain with IM ketamine (3-5mg/kg)
Oral ketamine sedation (burns) For an adult, give ketamine 500mg, diazepam 5mg For a child use ketamine (5-10mg/kg), diazepam (0.2mg/kg) The IV preparation of diazepam may be used for oral administration, it tastes bad, hide in juice.
Ketamine for postoperative analgesia Ketamine is a very good analgesic, may be used when morphine is unavailable Avoid hallucinations by using relatively low doses. Load with ketamine (0.1-0.3mg/kg) IV Infusion 50 mg ketamine in 500 ml fluid (0.1mg/ml) and run at (0.1-0.5mg/kg/hr)
Ketamine for treatment of asthma Ketamine is an effect bronchodilator and can be used for the patient not responding to conventional bronchodilators Low dose, hallucinations rare Load with (0.2mg/kg) IV, follow with an infusion at (0.5mg/kg/hr) for 3 hours.
Ketamine dosage review Intravenous administration: induction dose (0.5-2mg/kg), maintenance (0.5mg/kg) for anesthesia Intramuscular administration: induction dose (5-10mg/kg), maintenance (3-5 mg/kg) for anesthesia Oral administration sedation:(5-10mg/kg) for a child to a max of 500 mg for an adult
Spinal anesthesia Injection of local anesthesia in the subarachnoid space below the second vertebral body Easy to perform, best for surgery below the umbilicus Inexpensive, preserves respiration, gives good muscle relaxation, less blood loss
Spinal anesthesia disadvantages Failure to obtain anesthesia Hypotension – must be prepared to manage Pre-anesthetic fluid load may help prevent May not last long enough (2-3 hours) Possible infection Post-spinal headache
Spinal anesthesia indications may include Elderly Cardiac or respiratory disease C-section (dose reduction) Trauma if fluid resuscitation has been carried out
Spinal anesthesia contraindications Lack of resuscitative drugs and equipment Patient refusal Bleeding disorders Sepsis/septicemia Hypovolemia Neurologic disease Reluctant surgeon
Spinal anatomy Source: Kleinman W, Mikhail M: Spinal, epidural, and caudal blocks. In: GE Morgan Jr., Mikhail MS, Murray MJ (editors), Clinical Anesthesiology, McGraw-Hill, New York, 2005, p. 302.
Spinal anesthetic solutions Bupivacaine heavy: bupivacaine 0.75% in dextrose 2 ml vial (hyperbaric) Bupivacaine isobaric: bupivacaine 0.75% The baricity of the anesthetic influences how it spreads. The hyperbaric solution does not diffuse as rapidly as the isotonic solution Hyperbaric solution good for “saddle block”
Hypotension/bradycardia Manage aggressively If moderate hypotension/bradycardia use ephedrine (5mg-10mg) IV May repeat Phenylephrine (50-100mg) IV another choice If severe hypotension/bradycardia use epinephrine in increments of (20-40mcg) IV
WORLD ANESTHESIA ONLINE “Advancing Anaesthesia Throughout the Developing World “ Update in Anaesthesia: An educational journal aimed at providing practical advice for those working in isolated or difficult environments. http://www.nda.ox.ac.uk/wfsa/