Respiratory Flashcards
Which muscles tense and relax the vocal cords?
Cricoartyenoid - tenses the vocal cords, elongates them (SLN - external)
Thyroarytenoid - relaxes the vocal cords, shortens them
Vocalis - relaxes the vocal cords, shortens them
Which muscles abduct and adduct the vocal cords?
Lateral cricoarytenoid - aDDuction of glottic opening
Thyroarytenoid - aDDuction of glottic opening
Posterior cricoarytenoid - aBDuction of glottic opening
Describe the sensory innervation of the upper airway
Trigeminal Nerve (CN 5) has three branches
V1 = opthalamic (anterior ethmoidal nerve n.) sensory innervation to the nares and anterior 1/3 septum
V2 = mandibular (sphenopalatine n.) sensory innervation to the turbinates and septum
V3 = maxillary (lingual n.) sensory innervation to anterior 2/3 of the tongue, motor innervation to muscles of mastication.
Glossopharyngeal (CN 9)
-Sensory to the oropharynx, tonsils, soft palate, vallecula, anterior side of epiglottis, posterior 1/3 tongue
SLN - internal branch innervates the posterior side of the epiglottis to the level of the vocal cords
RLN - below vocal cords sensation to the trachea
RLN injury
unilateral = hoarseness (the ipsilateral vocal cord will assume a paramedian approach)
bilateral = emergent glottic closure of airway (if it is chronic, there is no respiratory distress)
Name 3 airway blocks and identify key landmarks for each one
GPN (bilateral) - palatoglossal arch at the anterior tonsillar pillar
SLN (bilateral) - greater cornu of hyoid bone
RLN - CTM
Where does the adult larynx extend from?
C3 - C6
Has 9 cartilages (3 paired, 3 unpaired)
What is the treatment for laryngospasm
- oxygen
- remove stimulus
- deepen anesthetic
- cpap 15 cm H2O
- chin lift, jaw thrust
- larson’s maneuver
- succ (4 mg/kg IM for adults & kids, 5 mg/kg for infants IM)
IV = 0.1 - 1 mg/kg
what law describes the respiratory muscle function
boyle’s law
describe the muscles of inspiration
-diaphragm contracts & pulls lungs down
-external intercostals expand a/p diameter
-accessory muscles = scalene and SCM
exhalation muscles
-typically passive
-forced = abdominus rectus, internal intercostals, EOM, IOM
minute ventilation vs alveolar ventilation
MVe = RR x TV (nml = 5 - 8 L)
Alveolar ventilation = (TV - Vd) X rr
what is compliance
change in volume/change in pressure
this is why alveoli in the base are more compliant compared to the apex
what does the V/Q ratio reflect
the ventilation to perfusion ratio (mve/CO) = 0.8
> 0.8 = dead space
< 0.8 = shunt
define the west zones of the lung
Zone 1 = dead space = V/Q= INFINITY
- PA > Pa > Pv
Zone 2 = watershed = v/q = 1
-Pa > PA > Pv
Zone 3 = shunt - V/Q = 0
-Pa > Pv > PA
Recite the alveolar gas equation
= FiO2 x (Pb - PH2O) - (PaCO2/RQ)
in a healthy patient breathing room air = 105.98
What is the A-a gradient, and what factors affect it?
Normal = 5 - 15 mmHg
Increased by high FiO2, aging, vasodilators, shunt, diffusion limitation
List the 5 causes of hypoxemia. Which ones do supplemental oxygen reverse?
-hypoxic hypoxia - o2 fixes (nml a-a gradient)
-hypoventilation - o2 fixes (nml a-a gradient)
-v/q mismatch - o2 fixes
-diffusion limitation - o2 fixes
-shutn - o2 does not fix
give reference values for the 5 lung volumess
TV = 500 mL
IRV = 3,000 mL
RV = 1,200 mL
ERV = 1,100 mL
What factors influence FRC?
FRC = RV + ERV (35 mL/kg)
-conditions that reduce outward lung expansion and/or reduce lung compliance
-when FRC is reduced, intrapulmonary shunt (Zone III) increases.
what test can measure FRC
nitrogen washout
helium wash in
body plethysmography
what is closing volume and what increases it?
the volume about FRC where small airways begin to close.
-COPD
-LVF
-Obesity
-SUrgery
-Extremes of age
-Pregnancy
State the equation and normal value for oxygen-carrying capacity and delivery
CaO2 = 1.34 x Hgb x SaO2 + (.003 x PaCO2)
normal = 20 mL O2 /dL
DO2 = CaO2 x 10 x CO
normal = 1,000 mL O2/m
Left shift of oxyhgb curve
decreased CO2, 2,3,DPG, temperature
increased fetal hgb, HgbCO, HgbMet
How is carbon dioxide transported in the blood
70% - bicarbonate
23% - bound to hgb
7% - dissolved into blood
Describe the Bohr Effect
In the presence of excess CO2, the hemoglobin releases oxygen more readily.
Describe the Haldane Effect
deoxygenated blood can carry more CO2 than oxygenated blood. B/C increased oxygen causes the erythrocyte to release CO2
List 3 causes of hypercarbia
- increased CO2 production (severe shivering, sz, burns, overfeeding)
- decreased CO2 elimination (increased dead space, opioid OD)
- rebreathing
Describe the four areas in the respiratory center
-DRG (medulla … specifically in the NTS)
It is the pacemaker for inspiration. Primarily for active inspiration.
-VRG (medulla … specifically in the NTS and nucleus retro ambiguous)
Has inspiration and expiration function. Primarily active during expiration. Quiet during normal breathing. Active when Ve increase. CAUSES EXPIRATION
-Pneumotaxic center (upper pons) inhibits DRG
Triggers the end of inspiration. Strong stimulus = rapid, shallow breathing. Weak stimulus = slow, deep breathing
-Apneustic center (lower pons) stimulates DRG
antagonizes the pneumotaxic center which causes inspiration. This action is inhibited by the pulmonary stretch receptors (J receptors)
Contrast the location and function of the central and peripheral chemoreceptors
Central chemoreceptor = located in the medulla. Responds to the hydrogen ion concentration in the CSF.
Peripheral chemoreceptors = located in carotid bodies (Nerves of Hering –> GPN CN 9) and also located in aortic arch (vagus n). Respond to hypoxia, hypercarbia, and increased hydrogen ions.
Which reflex prevents overinflation of the lungs
Hering-Breuer Inflation Reflex
Stimulus = 1.5 L
Afferent via CN 10
Efferent via phrenic n (C3 - C5)
What is HPV?
Minimizes shunt by reducing blood flow through poorly ventilated alveoli. Think atelectasis or OLV.
A low alveolar PO2 (NOT ARTERIAL) is the trigger that activates HPV
The effect beings immediately and reaches its full effect in 15 minutes
What things impair HPV? What is the consequence of this?
Halogenated anesthetics > 1 - 1.5 MAC
PDE inhibitors
Dobutamine
Vasodilators
What does the diffusing capacity for carbon monoxide (DLCO) tell us?
Normal = 17 - 25 mL/CO/m/mmHg
Using Fick’s law of diffusion, DLCO tells us (surface area i.e., decreased by emphysema) and thickness
Describe the short term benefits of smoking cessation
P50 normalizes within 12 hours (CaO2 improves)
t 1/2 of carbon monoxide 4 - 6 hours
SNS stimulating effects dissipate after 20 - 30 minutes
Describe the intermediate benefits of smoking cessation
within 6 weeks
-decreased sputum production
-improved mucociliary clearance
-hepatic enzyme induction normalizes in 6wks
-improved immune function
compare and contrast pulmonary function tests in obstructive vs restrictive
FEV1 & FVC <70% in restrictive dx
FEV1/FVC < 70% in obstructive dx (FEF25-75 & FEV1 also decreased)
Extrathoracic vs intrathoracic obstruction
-extrathoracic is normal flow on expiration
-intrathoracic is normal flow on inspiration
what is alpha 1 antitrypsin deficiency?
alveolar elastase is a normally occurring enzyme that breaks down pulmonary connective tissue and it is kept in check by alpha-1 antitrypsin
when there’s a deficiency in A1A, pan lobular emphysema results. the only treatment is a liver transplant.
give examples of intrinsic lung disease (acute & chronic)
acute = aspiration, opioid OD, pulmonary edema, upper airway obstruction, NPPE
chronic = sarcoidosis, amiodarone induced pulmonary fibrosis
Give examples of extrinsic lung disease (acute & Chronic)
acute = pneumothorax, flail chest
chronic = neuromuscular disease, kyphosciolosis
Define pulmonary hypertension and discuss the goals of anesthetic management
PAH defined > 25 mmHg
Goals: decrease PVR, treat hypotension aggressively.
Discuss the pathophysiology of CO poisoning
CO reduces oxygen carrying capacity of blood. Left shift. Latches onto Hgb 200x. Oxidative phosphorylation is impaired.
-need co-oximeter b/c pulse oximeter falsely elevates
-cherry red appearance
-desiccated soda lime (des > iso»_space; sevo) can cause this.
Treatment of carbon monoxide poisoning
- oxygen
- hyperbaric oxygen if > 25%
- oxygen should remain on patient for 6 hours or until CO < 5%
*t 1/2 of CO = 4 - 6 hours on RA and 69 - 90 minutes with 100% FiO2
Absolute indications for OLV
- To avoid contamination (infection, hemorrhage)
- Control of ventilation (bronchopleural fistula, surgical opening of a major airway, large unilateral lung cyst/bulla, life-threatening hypoxemia)
- Unilaateral bronchopulmonary lavage (pulmonary alveolar proteinosis)
Relative indications for OLV
Surgical exposure (high priority) - TAA, pneumonectomy, thorascopy, upper lobectomy, mediastinal exposure
-Low priority: middle/lower lobectomy, esophageal resection, thoracic spinal surgery
Others: pulmonary edema s/p CABG, robotic mitral valve surgery, severe hypoxemia d/t lung dx
discuss how anesthesia in the lateral decubitus position affects v/q relationship
-nondependent lung: moves from flatter region (less compliance) to an area of better compliance (slope). Ventilation is optimal in this lung
-dependent lung: moves from the slope to the flatter area of the curve (less compliant). perfusion is best in this lung.
list 5 indications for a bronchial blocker
- child < 8 years old
- nasotracheal intubation
- tracheostomy
- have a single lumen ETT
- require intubation post surgery
how can the lumen of the bronchial blocker be used during OLV?
suction air out or provide oxygenation
cannot suction blood, mucus, etc
what is mediastinoscopy and why is it performed?
obtain biopsy of paratracheaal lymph nodes aat the level of the carina. this helps the surgeon stage the tumor prior to lung resection
potential complications of mediastinoscopy?
- HEMORRHAGE
- PNEUMOTHORAX
others: thoracic aorta hemorrhage, innominate artery compression, vena cava hemorrhage, trachea airway obstruction, chylothorax, phrenic and RLN damage
where do you place the pulse oximeter and NIBP cuff during mediasstinoscopy?
pulses ox - right hand
NIBP- left arm
What is the interincisor gap used for? What is normal?
Mouth opening. A smaller inter-incisor gap creates a more acute angle between oral and glottic openings.
Normal = 2 - 3 FB (4 cm)
What is TMD?
The distance between the mentum and hyoid bone. Tells you how much room you have to displace the tongue.
-Normal = > 6 cm (3 FB) but < 9 cm
What is the Mandibular Protrusion Test?
Upper Lip Bite Test
Class I = nml
2 = UI aligned with LI
3 = unable to align UI and LI (DAW) risk
What conditions impair AO mobility?
-Klippel Feil
-Trisomy 21
-Goldenhaur
-DM
-Rheumatoid Arthritis
-Ankylosing Spondylitis
How do you treat angioedema anaphylaxis?
epi
antihistamines
steroids
How do you treat angioedema (ACEi or hereditary?
-FFP
-C1 esterase concentrate
-Ecallantide (prevents conversion to bradykinin)
-Icatibant (blocks bradykinin)
What is Ludwig’s angina?
Bacterial infection (cellulitis) of the floor of the mouth. Secure airway via awake FOI or awake nasal intubation
List the types of OPAs.
- Guedel
- Berman
- Williams (FOI)
- Ovassapian (FOI)
When is an NPA contraindicated?
-Coagulopathy
-Fracture of cribriform plate (LeFort II, III), basilar fracture (racoon eyes, periorbital edema, rhinorrhea)
-nasal fracture
-previous transphenoidal hypophysectomy or caldwell-luc procedure
Recommended cuff pressures for LMA vs ETT
LMA = 60 cmH20
LMA PPV = 20 cm H2O (Proseal does 30, Unique does 20)
ETT= 25 cm H2O
Largest ETT that can be passed through each LMA
1 = 3.5
1.5 = 4
2 = 4.5
2.5 = 5
3 = 6
4 = 6
5 = 7
List 6 indications for Bullard
-small MO (> 7 mm)
-c-spine impaired
-short, thick neck
-Treacher Collins
-Pierre Robin
2 indications for RI
-unstable C-spine
-Upper airway bleeding
what can you do with an airway exxchange catheter
-use for DAW extubation b/c it can be left in place for 72 hours
-measure ETCO2
-insufflate O2
-jet ventilation
