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RESPIRATORY PHARMACOLOGY (anaesthetic agents, bronchodilators, steroids, mucolytics) Presented by Dr. Amit Aggarwal Moderator - Dr. Jyoti Pathania. INHALATIONAL ANESTHETICS.
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(anaesthetic agents, bronchodilators, steroids, mucolytics)
Presented by Dr. Amit Aggarwal
Moderator - Dr. Jyoti Pathania
Also, selectively interference with intercostal muscle function contributing to loss of chest wall stabilization
Mechanisms of Action (depressing smooth muscle contractility )
decreases in Intracellular Ca2+ conc.
inhibition of cell-membrane–associated Voltage dependent Ca Channels (VDCs), an action that reduces entry of Ca2+ into the cytosol.
stimulating efflux of Ca2+ and increasing uptake of Ca2+ into the SR
decrease in calcium sensitivity as a result of inhibition of protein kinase C activity
volatile anesthetic–induced bronchodilation also occurs via modulation of airway cholinergic neural transmission
Focal epithelial damage or inflammation in the small airways of patients with asthma or after exposure to allergen,, the bronchodilatory response to volatile anesthetics may be reduced
Normal Mucociliary Function –
Ciliary motion consists of a rapid stroke in a cephalad direction, followed by a slower recovery stroke in the opposite direction. Movements of cilia are closely coordinated to move matter toward the trachea efficiently(metachronism ). ATP-dependent
Both halothane and isoflurane transiently reduce phosphatidylcholine synthesis by alveolar cells in a dose-dependent manner. (By decreased Na+/K+ ATPase activity in alveolar type II cells )
There is potentially additive and deleterious role of volatile anaesthetics and mechanical ventilation on surfactant production , particularly in the presence of acute lung injury
With the exception of uncommon anaphylactoid reactions, these drugs have little effect on bronchomotor tone
Early(within 2 hrs of neuraxial inj)- systemic absorption of lipid soluble opioid like fentanyl
Delayed (after 2 hrs)- cephalad migration in csf and interaction with receptors in ventral medulla, by reletively poor lipid soluble opioid like morphine. ( charactersticaly after 6-12 hrs)
Hypoxia, hypercarbia, depressed conciousness,
midazolam 0.05+ fentanyl 2ug/kg IV
The critical determinant of the delivery of any particulate matter to the lungs is the size of the particles.
When administered by inhalation, it produces significant bronchodilation within 15 minutes, and effects persist for 3 to 4 hours. 2.5-5mg (0.5 to 1 ml of 0.5 % solution in 5 ml NS), every 15 min upto 4 doses , duration 4 hrs
antiinflammatory action -activates histone deacetylases in the nucleus -could decrease the transcription of several proinflammatory genes
In premature infants, episodes of prolonged apnea lasting more than 15 seconds can be eliminated by methylxanthines
saline cannot liquify or reduce the viscosity of respiratory secretions
saline injection provides a vehicle for transporting bacteria into the lower airways.
Oral expectorants bromhexine, guaphenesine – act by vagally mediated increase in airway secretions decreasing mucus viscosity, have not been shown to be effective
N-acetylcysteine (Mucomyst) sulfhydryl-containing tripeptide
acts by disrupting the disulfide bridges between mucoprotein strands in sputum
aerosol spray( irritating to the airway), or injected directly through tracheal tube
bronchoscopy (the NAC is then applied directly to the mucous plug).
Recombinant DNAase (dornase alfa) improves pulmonary function in chronic management of cystic fibrosis