74.INDUCTION DRUG OF CHOICE IN PATIENT WITH ASTHMA
A.KETAMINE
B.PROPOFOL
C.HALOTHANE
D.THIOPENTONE
ANS:PROPOFOL
Induction/Intubation: consider an LMA (less stimulating). Pre-induce with IV lidocaine (reduces airway reactivity). Propofol is the IV induction agent of choice, although ketamine, which induces bronchodilation through neural mechanisms and secondary to catecholamine release, should be considered in patients who are actively wheezing but have an urgent need for surgery and anesthesia. Propofol has been shown to produce less wheezing than thiopental and methohexital and less respiratory resistance than thiopental and etomidate Consider masking with an added volatile agent prior to direct laryngoscopy (deepens anesthesia, and sevoflurane is also a bronchodilator).
Maintenance: sevoflurane (bronchodilator), although a propofol TIVA may also be reasonable. Use short-acting paralytics so as to avoid reversal (neostigmine can cause bronchoconstriction, and outlasts atropine). Consider an IV lidocaine infusion throughout the case, although lidocaine, which reduces airway responsiveness, has been shown to increase airway tone in asthmatic volunteers. Consider maintaining with 50% oxygen, as an FiO2 of 1.0 may abolish hypoxic pulmonary vasoconstriction. Beware steroid dependence (HPA axis assumed dysfunctional up to 1 year after IV steroids) and have access to IV agents. Beware breath-stacking, and consider shortening the I:E ratio.
A.KETAMINE
B.PROPOFOL
C.HALOTHANE
D.THIOPENTONE
ANS:PROPOFOL
Induction/Intubation: consider an LMA (less stimulating). Pre-induce with IV lidocaine (reduces airway reactivity). Propofol is the IV induction agent of choice, although ketamine, which induces bronchodilation through neural mechanisms and secondary to catecholamine release, should be considered in patients who are actively wheezing but have an urgent need for surgery and anesthesia. Propofol has been shown to produce less wheezing than thiopental and methohexital and less respiratory resistance than thiopental and etomidate Consider masking with an added volatile agent prior to direct laryngoscopy (deepens anesthesia, and sevoflurane is also a bronchodilator).
Maintenance: sevoflurane (bronchodilator), although a propofol TIVA may also be reasonable. Use short-acting paralytics so as to avoid reversal (neostigmine can cause bronchoconstriction, and outlasts atropine). Consider an IV lidocaine infusion throughout the case, although lidocaine, which reduces airway responsiveness, has been shown to increase airway tone in asthmatic volunteers. Consider maintaining with 50% oxygen, as an FiO2 of 1.0 may abolish hypoxic pulmonary vasoconstriction. Beware steroid dependence (HPA axis assumed dysfunctional up to 1 year after IV steroids) and have access to IV agents. Beware breath-stacking, and consider shortening the I:E ratio.
Drugs considered safe for asthmatics
| Induction | Propofol, etomidate, ketamine, midazolam |
| Opioids | Pethidine, fentanyl, alfentanil |
| Muscle relaxants | Vecuronium, suxamethonium, rocuronium, pancuronium |
| Volatile agents | Halothane, isoflurane, enflurane, sevoflurane, ether (nitrous oxide) |
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