Pulmonary Flashcards
(46 cards)
Can esmolol be given to patients with asthma?
Yes, it has little effect on bronchial smooth muscle in low doses (non-specific beta blockers like metoprolol and labetolol should be avoided)
What is a normal V/Q ratio?
alveolar ventilation: 4L/min
pulmonary blood flor: 5L/min
V/Q ratio: 0.8
What are the ABG findings during an asthma attack?
always hypoxemia
early hypocarbia and respiratory alkalosis
late hypercarbia and respiratory acidosis (intubate)
Which pulmonary function test is independent of patient effort?
FEF25%-75%
What is normal tidal volume? Vital capacity? FRC? TLC?
tidal volume: 6-8 mL/kg
vital capacity: 10x tidal volume
FRC: 30-40 mL/kg
TLC: 5-6L in men, 4-5L in women
Which part of the flow-volume loop is affected by a variable extrathoracic obstruction? Intrathoracic?
Variable extrathoracic obstructions flatten the ispiratory limb
Variable intrathoracic obstruction flatten the expiratory limb
**fixed obstructions flatten both limbs**
What factors increase closing capacity?
increased age
small airway disease
smoking
How long should elective surgery be delayed for a URI?
controversial, 2 weeks after symptom resolution is reasonable
Who should get stress-dose steroids intra-operatively?
Patients with 2 weeks of systemic steroids over the past 6 months.
BUT
Reasonable to treat unexplained perioperative hypotension empirically
Should patients with severe asthma get pre-operative steroids?
a 5-day course of methyprednisolone is effective in reducing post-intubation bronchospasm
Should patients with asthma get IV lidocaine prior to intbuation?
No, it may cause paradoxical bronchospasm
Why shouldn’t nitrous oxide be given to patients with pulmonary HTN?
It can increase PVR
Which inhalational agents should be used for patients with reactive airway disease?
at > 1 MAC, sevoflurane is slightly superior to isoflurane as a bronchodilator
desflurane increases airway resistance and should not be used
Can succinylcholine be used in asthmatic patients?
Yes, the degree of histamine release is minimal and not associated with increased airway resistance
How do you calculate auto-PEEP on the ventilator?
airway pressure during expiratory hold - set PEEP
Describe the management of an acute increase in peak airway pressure intra-operatively.
increase depth of anesthesia
suction and check position of ETT
given beta agonists, ketamine, epinephrine
switch to an ICU vent (higher inspriatory pressures)
Heliox
V-V ECMO
What are the considerations for reversal of muscle relaxation in an asthmatic patient?
Neostigmine can cause bronchoconstriction
Try to avoid reversal or use higher doses of glycopyrrolate/atropine
What analgesic presents problems for asthmatic patients?
morphine - histamine release
NSAIDs - increased leukotrienes
Why does oxygen supplementation in patients with COPD lead to hypercarbia?
1) smaller tidal volumes
2) disruption of hypoxic pulmonary vasoconstriction
Where should the pulse oximeter be placed during mediastinoscopy?
On the right hand, to detect compression of the innominate artery
Where should the IV be placed during mediastinoscopy?
Upper extremity IVs are fine, but there should be a plan for lower extremity IV access in case of SVC hemorrhage
What are the advantages and disadvantages of a bronchial blocker?
Advantages:
can be used in patients too small for a DLT
can be used through a single-lumen tube (difficult airway, no need for exchange at end of case)
DIsadvantages:
unable to suction through
unable to apply CPAP through
difficult to position and maintain position
tracheal occlusion if dislodged
What are the wavelengths used for pulse oximetry?
660 nm: max absorption by deoxyhemoglobin
940 nm: max absorption by oxyhemoglobin
**Plethysmography allows sampling only arterial blood**
What is the timing of hypoxic pulmonary vasoconstriction during one-lung ventilation?
begins in 15 minutes
completes in 2 hours
reverts to normal several hours after OLV
