Ch 14 Low Cost Techniques

CHAPTER 14

LOW COST TECHNIQUES

Outline: Basic anaesthetic technique using the EMO and controlled ventilation Basic anaesthetic technique using the OMV and controlled ventilation Ketamine-relaxant anaesthesia and controlled ventilation Ketamine as a sole anaesthetic

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A BASIC ANAESTHETIC TECHNIQUE USING THE EMO AND CONTROLLED VENTILATION Outline of technique Induction with thiopentone 2-5mg/kg (or ketamine 1-2mg/kg). Intubation using suxamethonium (Scoline) 1mg/kg. • Ventilate with air and oxygen (4 L/min delivers FiO2 of 6080%) and ether 10%. • Intubate and secure the tube. • Continue ventilation with air and oxygen (4L/min) and ether 10%. Maintenance When the suxamethonium wears off: • Give 4-6mg pancuronium IV (50-100 micrograms/kg) or another non- depolarising drug such as vecuronium or atracurium. • Reduce the concentration of ether from 10% to 3%. • Turn off the entrained oxygen and continue ventilation with air. (If the suxamethonium has a prolonged action, turn down the ether from 10% to 3% in 4-5 minutes). Reversal with atropine/glycopyrrolate and neostigmine. Pre-operative management • Assess the patient's general condition very carefully, especially with regard to the cardiovascular and the respiratory system. • Before elective surgery, allow a minimum 6 hours fasting for solids and 2 hours for clear liquids. • Weigh all children under the age of 10 years and adults who are grossly under or over weight, pre-operatively. If facilities are available every patient should be weighed before anaesthesia. • Premedication A variety of premedicant drugs may be used. See Chapter 7 for more detail. Opiates should be avoided in the following patients: − Infants under the age of 6 months. − Patients with head injuries. − Patients requiring caesarean sections. − Very ill patients. − Ophthalmic patients. − Many anaesthetists do not give opioids to anyone as a premed.

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Atropine should be reduced by half in very hot climates. It should also be reduced in febrile patients and those with acute blood loss. It is best omitted in cases in which the pulse rate is above 120/min. Agents to reduce the acidity of gastric contents (if available) should always be considered. The following equipment should be available: laryngoscope, endotracheal tubes with connectors, LMAs, syringe, artery forceps, catheter mount, mask, airway, stethoscope, strapping and suction.

Fig 14.1 The intubating tray The standard EMO set-up with the Oxford inflating bellows and Ruben or Ambu E valves as described earlier, is used. A source of oxygen and the drugs used for resuscitation must be available in the operating theatre.

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Intra-operative management • Draw up the drugs and label the syringes. • Check the blood pressure. • Establish venous access. Induction: Firstly, preoxygenate the patient by giving oxygen via the face mask to breathe for at least 3 minutes (4L/min). In the fit patient give thiopentone 5mg/kg. In the poor risk patient give thiopentone in a smaller dose, e.g. 3-4mg/kg; or ketamine 1mg/kg IV. Thiopentone must always be used in a 2.5% solution for reasons described under the pharmacology of thiopentone. (See Chapter 6 page 59) A 2.5% solution of thiopentone is prepared by mixing 0.5g of powder with 20mls of water or 1.0g of powder in 40mls of water. The dose of thiopentone is reduced to 2-4mg/kg in the following situations: − Advanced age − Anaemia − Recent blood loss or hypovolaemia from any cause − Cardiac disease − Hypertension − Severely obese patients − Very ill patients from any other cause The dose may be increased to 6 mg/kg (if necessary) in: − Alcoholics − Drug abusers − Very apprehensive patients Ketamine 1mg/kg IV is used in the poor risk patient and may also be used at 1mg/kg IV as the induction agent for caesarean sections. In higher doses it may cause harmful prolonged contractions and foetal anoxia. Ketamine is not used in eclampsia and hypertensive patients. Intubation: This involves the use of a relaxant drug and an endotracheal tube. The relaxant drug used is suxamethonium chloride in a dose of 1 mg/kg IV. Infants and very young children will require a dose that is higher on a weight basis than adults. Infants are technically more difficult to intubate and they have a more dynamic circulation which makes the relaxant wear off more quickly. The endotracheal tube : Cuffed tubes are used routinely for adults. The average sized male would need size 8.5-9, the average sized female size 7.5-8. (For children see the guide to tracheal tube size in Paediatric anaesthesia Chapter 20) The size of an endotracheal tube is its internal diameter in mm.

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Once the relaxant drug has been given, prepare to ventilate the patient with a mask. The relaxant paralyses the patient for 3-5 minutes. While the relaxant is taking effect use the time as follows: 1st minute: − Ventilate the patient using the Oxford inflating bellows. − Use an anaesthetic mixture of ether 10%, air and oxygen. − Oxygen is entrained via a T piece and reservoir tube at 4L/minute. − When the jaw is relaxed insert a Guedel airway of the appropriate size. At first the ventilation is mainly to assist the patient's respiratory efforts. As the patient becomes fully paralysed the anaesthetist controls the patient's respiration completely.

Fig 14.2 Ventilating the patient and then inserting the laryngoscope

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2nd minute: − Intubate the patient using a tube of the appropriate type and size. 3rd minute: − Connect the endotracheal tube to the Ruben valve or Ambu E valve and the EMO/OIB set-up.

Fig 14. 3 Inserting the endotracheal tube Check the position of the tube by auscultation. Breath sounds must be heard equally on both sides of the chest. Inflate the cuff of the endotracheal tube until the leak of air around the tube disappears. Then clamp the cuff using an artery forceps. Insert an airway as a bite block.

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The anaesthetist must be satisfied with the movement of the chest with each respiration and the colour of the mucous membrane of the tongue. Then strap or tie the tube in place. The patient must be ventilated with the ether 10% /air /oxygen mixture while this procedure is carried out. Check the blood pressure at this stage. Cardiac arrhythmias can occur with high concentrations of ether 10-15%, so keep a finger on the pulse unless ECG monitoring is available. Maintenance of anaesthesia: This requires an anaesthetic mixture to keep the patient asleep and a relaxant to keep the patient paralysed and ventilated. The anaesthetic mixture used for maintenance is ether 2-3% and air. The suxamethonium used for intubation will show signs of wearing off in 3 –5 minutes. The patient may begin swallowing, moving limbs or attempting to breathe. When this occurs: •

A non-depolarising muscle relaxant should be given Doses: − Pancuronium 0.05-0.1mg/kg, or − Vecuronium 0.08-0.1mg/kg or − Atracurium 0.3-0.6mg/kg Ether relaxes skeletal muscles and adds to the effects of the nondepolarising muscle relaxants.

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Reduce the concentration of ether from 10% to 2-3%. Occasionally 3% ether is not sufficient to keep the patient asleep and ventilation with 6% ether may be required for a few minutes.

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Consider discontinuing the oxygen that was fed into the EMO circuit via the T-piece attachment. However, if the patient is hypotensive, with systolic blood pressure below 85mmHg, or hypoxic, the oxygen must be continued as before. If the patient is a "poor risk" for any reason at all, oxygen should be entrained at 2L/min during the entire anaesthetic. Ideally diathermy should not be used with this technique as ether plus oxygen is explosive. Finally oxygen should always be entrained in areas of high altitude.

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Ventilate the patient at a rate of 12-15 inflations/minute. Aim at a tidal volume 50% greater than the patient's resting tidal volume. Watch the patient's chest continuously during ventilation. The chest must rise during inspiration. Expiration must be longer than inspiration, with a ratio of 1:1.5 or 1:2 so that adequate time is given for the lungs to empty. The patient must be monitored carefully while under anaesthesia.

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Monitor the following vital signs: pulse, blood pressure, colour of the blood, colour of the mucous membrane of the lips, respiration, blood loss, urine output. Pulse oximetry and capnography, if available, are invaluable.

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Calculate requirements and give intravenous fluids as required.

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Turn down the ether concentration after the peritoneum is closed. Depending on the speed of the surgeon, the ether concentration can be turned off completely if you think the operation will be completed ten minutes after the peritoneum is closed. Maintain ventilation until the operation is over. If by this stage the patient is attempting to breathe spontaneously then the patient's respirations must be assisted.

Reversal: This is carried out after the last stitch is in place, when a standard dose of atropine 1.2mg / neostigmine 2.5mg or glycopyrrolate 0.5mg / neostigmine 2.5mg is given. Rules for extubation • The patient must be breathing deeply and regularly before extubation is attempted. • The patient should preferably be awake at the end of the procedure. • Oxygen (4L/min) should be given to the patient prior to extubation. • Suck out the pharynx then turn the patient into the lateral position. • Suck out the pharynx again before and after removing the tube. • Administer oxygen by mask after extubation and make sure the patient is breathing adequately. Watch the movement of the chest. • Observe the patient until fully awake. At this stage the patient can be sent back to the ward. Advantages of the low ether/relaxant technique The technique is safe • The patient is intubated and this reduces the risk of airway obstruction and laryngeal spasm. The trachea is protected against contamination in the case of a full stomach. However, it cannot be emphasised too much that intubation minimises but does not completely eliminate these risks. • The patient is ventilated, so an adequate tidal volume is maintained during surgery. IPPV is certainly safer in prolonged surgery and surgery performed in abnormal postures. A relaxant technique with a high concentration of oxygen is the safest anaesthetic in the seriously ill patient.

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Postoperative complications are reduced to a minimum. Only a very low concentration of ether is used –2-3%. At this concentration there is minimal central depression. The patient is awake at the end of the surgical procedure. Hence the incidence of post operative complications such as airway obstruction, vomiting and aspiration and chest complications e.g. atelectasis and pulmonary embolism is reduced significantly. Postoperative vomiting using the low concentration of ether is no more frequent than it is with a nitrous oxide / halothane / relaxant anaesthetic. The patient is able to get out of bed and also tolerate a normal diet (if appropriate) more quickly. The hazard of compressed gas cylinders running out unnoticed is less serious with the EMO technique. Good operating conditions are provided by this relaxant anaesthesia for most surgical procedures.

Cost • The capital outlay for the equipment used is much less with the EMO technique than with techniques using the conventional anaesthetic machine. • The drugs used are much cheaper. Ether costs much less than nitrous oxide and halothane. • The dose of relaxant required is much less with the EMO technique than with a conventional nitrous oxide/oxygen/relaxant technique. Ether potentiates the non-depolarising relaxants and reduces the dose required. The volume of ether used is very low. Oxygen is often a very precious commodity in developing countries. Using oxygen only before intubation and again before and after extubation conserves the oxygen supply but if there is adequate oxygen it should be used for all patients and will help to reduce post-operative complications. Disadvantages of the technique • Ether is a flammable agent. Cautery must be attempted with caution and not with the use of oxygen. If you use this technique, you need to pay careful attention to the state of electrical equipment used in the operating room. If possible, electrical equipment should be at least 1 metre from the floor. • The help of an assistant is imperative if the patient is to be ventilated and monitored at the same time. • The use of a mechanical ventilator, a spirometer to ensure adequate tidal volumes and a scavenging device would greatly improve the technique.

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A BASIC TECHNIQUE USING THE OXFORD MINIATURE VAPORISER AND CONTROLLED VENTILATION Outline of technique Induction with thiopentone 2-5mg/kg (or ketamine 1-2mg/kg). Intubation using suxamethonium (Scoline) 1mg/kg. • Ventilate with air and oxygen (4L/min delivers FiO2 of 6080%) or 100% oxygen. • Intubate and secure the tube. • Continue ventilation with air and oxygen (4L/min) and halothane. Maintenance When the suxamethonium wears off • Give a non-depolarising drug such as pancuronium, vecuronium or atracurium • Continue ventilation with oxygen, air and halothane Reversal with atropine/ glycopyrrolate and neostigmine. Pre-operative management is the same as for using the EMO (see above) Preparation of the OMV with Oxford Inflating Bellows (OIB) and a non-rebreathing valve • Fill with halothane up to the line indicated on the glass window. • Check that the pointer is sliding freely. • Disable the proximal valve nearest the patient on the OIB to allow proper function of the non-rebreathing valve. • Check the apparatus for any leaks in the system. • Check the non-rebreathing valve shutters are moving freely. As in the use of the EMO a source of oxygen and the drugs used for resuscitation must be available in the operating theatre. Intra-operative management. Induction and intubation is the same as for using the EMO (see above) but during the intubation: 1st minute: − Ventilate the patient using the Oxford inflating bellows with oxygen 95% or 100%. − When the jaw is relaxed insert a Guedel airway of the

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appropriate size.

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At first the ventilation is mainly to assist the patient’s respiratory efforts. As the patient becomes fully paralysed the anaesthetist controls the patient’s respiration completely. 2nd minute: − Intubate the patient using a tube of the appropriate type and size. 3rd minute: − Connect the endotracheal tube to the Ambu E or Ruben valve OMV/OIB set-up. Check the position of the tube by auscultation. Breath sounds must be heard equally on both sides of the chest. Inflate the cuff of the endotracheal tube until the leak of air around the tube disappears. Then clamp the cuff using an artery forceps. Insert an airway as a bite block. Check the movement of the chest with each respiration and the colour of the mucous membrane of the tongue. Then strap or tie the tube in place. Ventilate the patient with halothane at mark 1 on the dial and an oxygen / air mixture while this procedure is carried out. Check the blood pressure at this stage. If the BP is high halothane at mark 2 may be given for a short time but continue to measure the BP every 2 minutes to detect any sudden fall in BP. Hypotension is likely and cardiac arrhythmias can occur with high concentrations of halothane. Maintenance of anaesthesia: This requires an anaesthetic mixture to keep the patient asleep and a relaxant to keep the patient paralysed and ventilated. The anaesthetic mixture used for maintenance is halothane mark 1 with air / oxygen and most anaesthetists would add a dose of IV opioid. The suxamethonium used for intubation will show signs of wearing off after 3-5 minutes. The patient may begin swallowing, moving limbs or attempting to breathe. When this occurs: • A non-depolarising muscle relaxant should be given Doses: − Pancuronium 0.05mg/kg, or − Vecuronium 0.05mg/kg or − Atracurium 0.2mg/kg • If the patient becomes hypotensive turn off the halothane until the hypotension is corrected. (If the patient is likely to awaken a ketamine infusion of 500mg/500mls of dextrose 5% or normal saline at a rate of 0.5 drops/kg to keep the patient asleep and provide analgesia could be commenced). • Ventilate the patient at a rate of 12-15 inflations /minute.

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Aim at a tidal volume 50% greater than the patient’s resting tidal volume. Watch the patient’s chest continuously during ventilation. The chest must rise during inspiration. Expiration must be longer than inspiration, with a ratio of 1:1.5 or 1:2 so that adequate time is given for the lungs to empty. The patient must be monitored carefully while under anaesthesia. Monitor the following vital signs: pulse, blood pressure, colour of the blood, colour of the mucous membrane of the lips, respiration, blood loss, urine output. Pulse oximetry and capnography, if available, are invaluable. Calculate requirements and give intravenous fluids as required.

When using halothane turn it off depending on the speed of the surgeon and length of the incision when the skin wound is sutured. When using a ketamine infusion turn off the ketamine when the surgeon commences suturing the skin. Maintain ventilation until the operation is over. If by this stage the patient is attempting to breathe spontaneously then the patient’s respiration must be assisted. Reversal: This is carried out after the last stitch is in place, when a standard dose of atropine 1.2mg / neostigmine 2.5mg or glycopyrrolate 0.5mg / neostigmine 2.5mg is given. Rules for extubation as for using the EMO (see above) Advantages of the halothane/relaxant technique using the OMV • Similar to ether although halothane is a more expensive agent and does not potentiate the effect of muscle relaxants to such a great extent as ether. • Halothane is non-flammable so the use of diathermy is safe. Disadvantages of the technique • Halothane may cause cardiac arrhythmias. • Halothane may cause hypotension.

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THE KETAMINE-RELAXANT ANAESTHESIA AND CONTROLLED VENTILATION This is another technique providing anaesthesia for major surgery. The equipment required is simple • A means of ventilating the patient, e.g. a self-inflating bag or the Oxford inflating bellows. The Oxford inflating bellows has an oxygen nipple on the side. • An oxygen source. • Suction. • Equipment for intubation. • Equipment for monitoring the patient. The drugs required • Ketamine infusion prepared by using 500mg ketamine in 500mls 5% dextrose or 0.9% saline. Use a normal adult giving set with 15 drops = 1ml (i.e. 1mg = 1ml). • Suxamethonium 1mg/kg. • Any non-depolarising relaxant. • Neostigmine and atropine for reversal of the relaxant. • Diazepam. • Drugs used for resuscitation. Pre-operative management Perform a routine assessment of the patient and then give premedication of diazepam or opioid and atropine. Intra-operative management Check the blood pressure and insert an intravenous cannula. Induction: This is achieved with ketamine 2mg/kg IV and diazepam 5mg IV in the fit adult. Intubation: Suxamethonium 1mg/kg, then ventilation using a self-inflating bag or the Oxford inflating bellows. Ventilate the patient for 1 minute with air and oxygen and intubate as described for the EMO technique. Check the position of the tube and secure it.

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Maintenance: The ketamine infusion containing 500mg of ketamine in 500mls of 5% dextrose is commenced. The infusion rate of 40-60 drops / minute (0.5-1 drop/min/kg). This is equivalent to 2-4mg/kg/hour. Give a dose of a non-depolarising relaxant when the suxamethonium wears off. Ventilation is carried out with air, and oxygen is added if necessary. Vary the rate of the ketamine infusion to keep the patient asleep and free from pain. Depth of anaesthesia is hard to assess with this technique. Observe closely for changes in pulse rate and BP. Stop the drip 10 minutes before the end of the operation. Reversal of relaxant:

Atropine 1.2mg. or glycopyrrolate 0.5mg plus neostigmine 2.5mg. Take the same precautions as described for the EMO technique regarding reversal and extubation. Two disadvantages that may be encountered with this technique are: • Hypertension. • Hallucinations. THE USE OF KETAMINE AS A SOLE ANAESTHETIC • •

Bolus  IV or IM As an infusion

The pharmacology of ketamine has been discussed earlier. Ketamine is useful as the sole anaesthetic in the following situations, provided certain precautions are taken. Indications for ketamine • Cystoscopies • Dilatation and curettage • Closed reduction of fractures (note that ketamine provides no muscle relaxation) • Removal of foreign bodies from the ears, nose and subcutaneous tissues • Suture of lacerations • Incision of abscesses • Other minor procedures, e.g. anal, or urethral dilations, etc. Precautions to be taken • Select patients carefully. • A premedication of atropine is sometimes given (see below). • Use IV diazepam to reduce the emergence delirium.

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Allow patient to awaken spontaneously after surgery in quiet surroundings.

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Patient Selection Patients must be medically fit for an anaesthetic. The usual criteria in selecting patients for general anaesthetic should be applied. Acute respiratory infection, cardiac failure, electrolyte imbalance, etc. would be a relative contraindication to ketamine anaesthesia. Ketamine must not be used in patients with hypertension, raised intracranial pressure (e.g. following a head injury) or raised intraocular pressure. Patient should be fasted according to the guidelines for any general anaesthetic. (See Chapter 7) Every patient receiving a ketamine anaesthetic should be weighed.

Premedication A drying agent such as hyoscine, atropine or glycopyrrolate can be used. Bolus technique • Record the patient's blood pressure before giving the ketamine. Leave the cuff in place for blood pressure recordings during surgery. • Access a vein, using a scalp vein needle or IV cannula. • Give diazepam in a dose of 0.1mg/kg IV. • Dose: Give ketamine 2 mg/kg IV slowly over 1 minute (in the fit patient), or 5-7 mg/kg IM. The onset of action is 30 seconds IV or 2-8 minutes IM. Duration is 5-10 minutes IV or 10-20 minutes IM. If further supplements are required half the initial dose of ketamine may be used. The same dose of diazepam may be repeated. Ketamine infusion technique Indications: Most of the procedures listed above and also longer procedures not requiring muscular relaxation, e.g. herniotomy in an older child. Pre–operative Management Assessment and pre-medication are the same as for other ketamine anaesthetics. Prepare ketamine solution 1mg/ml (i.e. 10mls of 50 mg/ml ketamine in 500mls of normal saline or 5% dextrose). Start IV infusion of 0.9% saline, 5% dextrose or dextrose/saline mixture. Use a cannula in a larger vein. When commencing the anaesthetic, change to the ketamine infusion.

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Intra-operative Management Induction and maintenance • Induction with bolus: IV ketamine 1-2 mg/kg and diazepam (Valium) 0.1 mg/kg or start drip at 2 drops/kg/min until surgical anaesthesia is reached. At this point the patient does not respond to pain but still has the eyelash and pharyngeal reflexes. • Slow the infusion to 1 drop/kg/min (= 4mg/kg/hour). • If the patient seems to react to the pain of the operation, increase the drip rate to 2 drops/kg/min until operating conditions are satisfactory. • Monitoring is routine as for other ketamine anaesthetics, e.g. pulse, BP, respiration, colour and oxygen saturation if available. • Stop drip about 10 minutes before the end of surgery. Post-operatively The patient must be nursed in a quiet environment and should be observed but must not be stimulated after surgery. Treatment of emergence reactions If emergence reactions or hallucinations occur, the following drugs will be useful: • Diazepam. • Chlorpromazine. • Pethidine (in combination with the other drugs) if the patient is in pain. Reassurance of the patient and relatives is important. Other intra-operative disadvantages of ketamine • Hypertension • Occasional respiratory depression

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