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Anaesthesia with chronic obstructive pulmonary disease (COPD)

  1. Choice of Anaesthesia
    Regional preferred over general anaesthesia. But spinal above T8 level can compromise ventilatory function so high spinal is not recommended.
  2. General anaesthesia
    1. Ketamine is better induction agent.
    2. Nitrous oxide should not be used is emphysema (can increase the size of bullae and can make them rupture). So maintenance is done on oxygen and inhalational agent (halothane).
    3. Opioids should be avoided (can cause respiratory depression).
    4. During IPPV large tidal volumes (10 to 15 ml/kg) and less respiratory rate (6 to 10 breaths / minute). Should be used (to increase exhalation time).
    5. Humidified gases should be used.

Anaesthesia with asthma

  1. Choice of anaesthesia
    Regional preferred over general anaesthesia but blocks above T8 are not recommended.
  2. General anaesthesia
    1. Induction agent of choice is ketamine. Maintenance by oxygen, nitrous oxide and halothane.
    2. Relaxant: Benzylisoquinoline derivative (atracurium) should not be used (these agents release histamine and can cause severe bronchospasm). So steroidal agents (vecuronium) should be used.
    3. Interaction with aminophylline is important consideration. It sensitizes myocardium to adrenaline and arrhythmias can occur if halothane is used.
Anaesthesia For Asthma
  1. Volatile anaesthetics are bronchodilators and are therefore generally well tolerated -t amongst the volatile agents halothane is preferrable as it causes maximum bronchodilation.
  2. Amongst the intravenous agents, only ketamine causes bronchodilatation. However, Thiopental is most commonly used for adults, but occasiortally can induce bronchospasm as result of exaggerated histamine
  3. Release. Propofol and etomidate are suitable alternatives and, infact, are preferred by some clinicians.
  4. Halothane and sevoflurane usually provide smoothest inhalational induction with bronchodilatation in children.
Drugs considered safe for asthmatics
Induction Propofol, etomidatc, ketarnine
Opioids Pethidine, Fentanyl, alfentanil
Muscle relaxants Vecuronium, rocuronium, Pancuronium
Volatile agents Halothane, Isoflurane, Sevoflurane, Desflurane, Np
Other Benzodiazepines (Amongst hypnotics, BZD are safe) (J'GJOI).
  1. Drugs often associated with histamine release should be avoided: - Curare, atracurium, mivacurium, suxamethonium, morphine and mepridine.
  2. Above description was for anaesthesia in asthmatic patient in general. However, if patients is having status asthmatieust-
    1. Ketamine is the intravenous inducing anaesthetic of choice (A1JMS97).
    2. Halothane is the inhalational agent of choice.
    3. Halothane or sevoflurane are the agent of choice ill children.
    4. Though thiopentone is used in simple Asthma, it is contraindicated in status asthmaticus.
      • Ketamine should not be used in patients with high theophylline levels, as the combined actions of the two drugs can precipitate the seizure activity.

Anaesthesia with Epilepsy

These patient are on anticonvulsant which effect the organ systems. So organ function (especially liver function tests) should be done in preoperative evaluation.
Anesthetic drugs, which have got epileptogenic potential and should not be used are:
  1. Induction agent
    1. Methohexital
    2. Ketamine (due to its preservative)
  2. Inhalational agent.
    1. Enflurane
  3. Muscle relaxant
    1. Atracurium (its metabolic product laudanosine is epileptogenic)
  4. Local anaesthetic (toxicity).
    1. Induction agent of choice for epileptics is thiopentone (strong anticonvulsant) and anaesthesia is maintained on oxygen, nitrous oxide (or opioid), isoflurance or halothane and muscle relaxant other than atracurium.
    2. Spinal/epidural can be given safely if there are no signs and symptoms of raised ICT.

Anesthesia in myasthenia gravis

Local anaesthesia, peripheral nerve blocks and central neuraxial blocks (below T8 which does not compromise ventilatory functions) is preferred over general anaesthesia.
  1. Monitoring: Other than routine monitoring neuro-musclar monitoring is mandatory.
  2. Induction: With thiopentone.
  3. Intubation: Can be performed without muscle relaxant in many patients. Some patients require inhalational agent for intubation. Very few patients will require relaxant. The does of succinylcholine is increased.
  4. Muscle relaxant: These patients are resistant to depolarizing agents and hypersensitive to nondepolarizing agents
  5. (Due to less number of acetylcholine receptors available for competitive antagonism). So potent nondepolarzing agents like tubocurare, gallamine, metocurine and pancuronium should not be used.
  6. Maintenance: Anaesthesia is maintained on depolarizing muscle relaxant is required short acting (like mivacurium, atracurium) in 1/10th dose should be given as initial dose and further doses titrated as perneuromuscular monitoring. Many of these patients require ventilation in postoperative period.

Anesthesia with renal disease

  1. Induction: Barbiturates (thiopentone) is required in small doses because of exaggerated response of CNS due to disrupted blood brain barrier in uremia.
  2. Relaxants: As these patients exhibit hyperkalemia therefore succinylcholine should not be used. Nondepolarizing relaxant of choice is atracurium.
  3. Inhalational Agents: Methoxyflurane and sevoflurane can induce nephrotoxicity by fluoride ions, so should not be used, desflurane and halothane can be safely used.
  4. Oxygen is given in high concentration because these patients are anaemic.

Anesthesia for Trans urethral resection of prostate (TURP)

Spinal anesthesia preferred over general anesthesia because of the following reasons:
  1. Old patients have decreased pulmonary reserve.
  2. Awake patient can tell central signs of TURP syndrome.
  3. Accidental perforation of bladder may manifest as referred pain to shoulder (irrigating fluid through perforation can irritate diaphragm).
    • A level upto T10 is required.

Anesthesia with hyperthyroid

  1. Induction: Thipentone is drug of choice because of its antithyroid property.
  2. Ketamine should not be used as it can cause tachycardia and hypertension.
  3. Cardiovascular responses to intubation should be blunted and difficult intubation due to enlarged gland may be anticipated. Anesthesia is maintained on oxygen, nitrous oxide and isoflurance or desflurane. Halothane with increased metabolism in hyperthyroid patient can produce hepatotoxicity and enflurane, sevoflurane and emthoxyflurane can be nephrotoxic. As one expects that MAC of inhalational agent should increase in hyperthyroid patient but this is not seen because of increased metabolism and increased cardiac output.
  4. Muscle relaxants: Pancuronium should be avoided as it can cause tachycardia. Vecuronium is good choice.

Anesthesia with Hypothyroidism

  1. Elective surgery should be deferred till patient is euthyroid.
  2. Eltroxin should be continued in perioperative period.
  3. Preoperative Evaluation
  4. Hypothyroid patients can have very large glands, so indirect laryngoscopy or if required CT neck should be done.
  5. These patients are very sensitive to depressant drugs so premedication is to be avoided.
    Intra operative
  6. These patient are vulnerable to go into congestive cardiac failure so for major surgeries central venous pressure (CVP) monitoring is desirable.
    1. Induction: Accomplished by ketamine. Intubation is done with succinylcholine as usual.
    2. Maintenance: Maintained on oxygen, nitrous oxide and intermittent small doses of ketamine. Inhalational agents should be avoided because these agents can produce severe cardiac depression in hypothyroid patients.
    3. Muscle relaxant: intermediate acting like atracurium should be used in minimum doses with neuromuscular monitoring.


Physiological changes in pregnancy
  1. Cardiovascular system
    1. Intravascular fluid volume by 35%
    2. Cardiac output by 40%
    3. Systemic vascular resistance by 15%
    4. Heart rate by 15%
    5. Systolic blood pressure No Change
  2. Respiratory system
    1. Tidal volume by 40%
    2. Respiratory rate by 10%
    3. Minute ventilation by 50%
    4. Functional residual capacity by 20%
    5. Expiratory reserve volume (due to gravid uterus causing diaphragmatic elevation)
    6. Residual volume
    7. Vital capacity No change
    8. Airway resistance by 35%
    9. Oxygen consumption by 20%

Blood Gases

  1. paO2 by 10mm Hg Due to Hyperventilation
  2. pCO2 by 10mm Hg
  3. pH   No change due to compensatory mechanism

Anesthetic implications of respiratory changes

  1. Due to increased minute ventilation, the induction with inhalational agents is faster and dose requirement is less making pregnant patients more susceptible to anaesthetic overdosage.
  2. Due to decreased FRC, ERV and increased oxygen requirement these patients are Vulnerable to go in hypoxia and preoxygenation for 5 to 6 minutes is required. This is the time required for maternal to fetal equilibrium.
  3. Due to capillary engorgement in upper airways chances of trauma and bleeding during intubation are high.
  4. Laryngeal edema may be a prominent feature in PIH patients, making intubation difficult.

Anaesthesia for cesarean section

  1. Regional anaesthesia is preferred over general anaesthesia.
    Advantages of Regional (Spinal/Epidural) over General Anaesthesia
    1. Risk of pulmonary aspiration is obviated.
    2. Effect of anaesthetic drugs on fetus is not seen.
    3. Awake mother can interact with her newborn immediately after surgery.
    4. High inspired concentration of oxygen to mother can be delivered.
  2. Analgesia for labour (painless labour)
    Pain afferents from uterus and cervix travel up to T10 - L1.
  3. Lumbar epidural
    Lumbar epidural is instituted only when first stage of labour is well established i.e., cervix is at least 4 to 6 cm dilated. Epidural catheter is placed in lumbar space (usually L3-4) and 6 to 8 ml of bupivacaine (0.25%) and fentany1 100 mg is maintained through epidural catheter. At this concentration of bupivacaine only sensory fibres are blocked. So patient can easily bear down during delivery.
  4. Anaesthesia for pregnancy induced hypertension (PIH) pre-eclampsia
    The technique of choice is epidural anaesthesia for the following reasons:
    1. These patients can manifest severe, uncontrollable hypotension with spinal (hypertensives are more prone for hypotension after spinal).
    2. Intubation may be very difficult in PIH patients as these patients have laryngeal edema.

Pediatrics Anesthesia

  1. Anaesthesia in pediatrics
    1. Paediatrics patients have number of physiologic differences from adults.
    2. Respiratory system
  2. Airway Anatomical Differences
    1. Large head size.
    2. Large tongue.
    3. Epiglottis is mobile.
    4. Larynx is anteriorly placed.
    5. Subglottis (at the level of cricoid) is the narrowest part (while in adults glottis is the narrowest part of larynx).
  3. Anaesthetic implications
    1. Due to large head and anteriorly placed larynx the intubation is better in neutral or slightly flexed position of head (while in adults there is extension at atlanto-occiptal joint during intubation).
    2. Due to anatomical configuration laryngoscope with straight blade (Magill) is used for intubation in infants.
    3. Large tongue can obscure the view.
    4. Since subglottis is the narrowest part so uncuffed.
  4. Physiologic changes
Parameter Value(Neonate) Adult
Tidal volume 6 to 8 ml/kg 6 to 8 ml/kg
Respiratory Rate 35/minute 14 to 16 minute
Alveolar ventilation 120-140 ml/kg/minute 60-70 ml/kg/minute
Oxygen Consumption 6 ml/kg/minute 3 ml/kg/minute
Calorie requirement 100 kcal/kg 30 Kcal/kg
In children Oxygen consumption is twice of adults and calorie requirement is thrice. The tidal volume on body weight basis is same so respiratory rate is important. 
Child Adult
pH 7.34 to 7.40 7.36 to 7.44
pO2 65-85 mmHg (at birth) (intrauterine pO2 is 25 to 40 mmHg) 95-97 mm Hg
pCO2 30 to 36 mmHg 35 to 45 mmHg
  1. Metabolic
    1. Children are very prone to hypoglycemia so intraoperative fluids must contain glucose and the fasting requirement in children are:
Age Milk and Solid Clear liquid (water)  
<6 months 4 hours 2 hours
6 months – 3 year 6 hours 3 hours
>3 years 8 hours 3 hours
  1. Neuromuscular junction
    1. Functional maturation of NM junction is not complete until 2 months of age so newborns are very sensitive to nondepolarzing muscle relaxants.
    2. Atracurium is the relaxant of choice as it does not depend on hepatic and renal functions.
    3. Succinylcholine should be avoided in newborns due to presence of extrajunctional receptors.
    4. Induction in children
      1. Inhalational Induction: Inhalational induction is the method of choice for induction in children and sevoflurane is the inhalational agent of choice but due to high cost, halothane is still most commonly used agent.
      2. Important precaution is to put an intravenous line once the child falls asleep before proceeding to deeper plane.
      3. Intramuscular: Ketamine 5 mg/kg is used IM injection can be given in preoperative room with child in parent’s lap.

Anaesthesia for management of burns patient

Usual surgeries done in burn patients are release of post burn contracture and split skin grafts.
  1. Venous access may be very difficult and may require central line at times.
  2. Difficult airway: Due to contracture of face and neck, mouth opening and neck movements are inadequate making intubation very difficult and impossible at times. In these cases blind nasal awake intubation may be tried or contracture released under intravenous ketamine and then intubation is done.;
  3. Dose for intravenous induction agent may be slightly higher because of large volume of distribution (hyperdynamic circulation) and increased metabolism.
  4. Increased protein loss can lead to increased unbound fraction of benzodiazepines and thiopentone.
  5. Muscle relaxants:
  6. Depolarizing muscle relaxants (Succinylcholine) is contraindicated for one years as there are high chances of hyperkalemia.
  7. There is increased resistance to nondepolarizing muscle relaxants due to extrajunctional receptors in burn patients.-

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