Apex Unit 1 Flashcards Resp
what does thyroarytenoid muscle do?
shorten the cords THEY RELAX
what dos cricothyroid muscle do
elongates the cords CORDS TENSE
what dos posterior cricoarytenoid do?
ABducts
what does Lateral cricoarytenoid do
ADducts
what are 2 attachment point for vocal cords
thyroid cartilage and the arytenoid cartilage
how is cricothyroid ligament innervated from
SLN (external)
whihch muscles depress the larynx
omohyoid, sternohyoid, sternothyroid
which muscles elevate the larynx
stylohyoid geniohyoid mylohyoid thyrohyoid digastric stylopharyngeus
the superior laryngeal nerve innervates the
underside of epiglottis (internal) & cricothyroid muscles (external)
what do the R & L RLN loop under
R - subclavian
L - Aortic arch ( more susceptible to injury)
what are the three branches of trigeminal nerve
V1: ophthalmic
V2: maxillary
V3: Mandibular
what does glossopharyngeal nerve innervate
soft palate, tonsils, posterior 1/3 of tongue, vallecula, afferent limb of GAG
whats does SLN external innervate (sensory)
nothing
what does SLN internal innervate (sensory
posterior side of epiglottis
what does RLN innervate
area under vocal cords - trachea
How does superior laryngeal nerve injury affect the integrity of the airway?
Superior laryngeal nerve injury
Bilateral: Hoarseness / No respiratory distress
Unilateral: No respiratory distress
Name 3 airway blocks, and identify the key landmarks for each one.
Glossopharyngeal nerve block: Palatoglossal arch at the anterior tonsillar pillar
Superior laryngeal nerve block: Greater cornu of hyoid
Transtracheal nerve block: Cricothyroid membrane
What are the 3 paired and 3 unpaired cartilages of the larynx?
unpaired = epiglottis thyroid, cricoid paired = corniculate, arytenoid, cuneform
What is the treatment for laryngospasm
Significant consequences of laryngospasm include hypoxia and negative-pressure pulmonary edema.
Treatment:100% FiO2 Remove noxious stimulation Deepen anesthesia CPAP 15 - 20 cm H2O Open the airway (head extension, chin lift) Larson’s maneuver Succinylcholine
Regarding succinylcholine:
Infants and small children should receive atropine 0.02 mg/kg with succinylcholine.
If no IV access, submental administration will produce the fastest onset.
If no IV access and the patient can’t have succinylcholine, then rocuronium is the only other NMB that can be given IM.
Describe how the respiratory muscles function during the breathing cycle.
Contraction of the inspiratory muscles reduces thoracic pressure and increases thoracic volume. This is an example of Boyle’s law.
Inspiration:
The diaphragm and external intercostals contract during inspiration (tidal breathing).
The diaphragm increases the superior-inferior dimension of the chest.
The external intercostals increase the anterior-posterior diameter.
Accessory muscles include the sternocleidomastoid and scalene muscles.
Exhalation:
Exhalation is usually passive; this process is driven by the recoil of the chest wall.
Active exhalation is carried out by the abdominal musculature (rectus abdominis, transverse abdominis, internal obliques, and external obliques).
The internal intercostals serve a secondary role in active exhalation.
Exhalation becomes an active process when minute ventilation increases or in patients with lung disease, such as COPD.
A forced exhalation is required to cough and clear the airway of secretions.
What is the difference between minute ventilation and alveolar ventilation?
Minute ventilation (Ve) is the amount of air in a single breath multiplied by the number of breaths per minute.
Ve = Vt x RR
Alveolar ventilation (VA) only measures the fraction of Ve that is available for gas exchange. Said another way, it removes anatomic dead space gas from the minute ventilation equation.
VA = (Vt - Anatomic dead space) x RR
VA is directly proportional to CO2 production
VA is indirectly proportional to PaCO2
Define the 4 types of dead space.
Anatomic Vd:
Air confined to the conducting airways
Alveolar Vd:
Alveoli that are ventilated but not perfused
Physiologic Vd:
Anatomic Vd + Alveolar Vd
Apparatus Vd:
Vd added by equipment
Provide an example for each type of dead space.
Anatomic Vd:
Nose/mouth → terminal bronchioles
Alveolar Vd:
Reduced pulmonary blood flow (↓ CO)
Physiologic Vd:
Anything that increases anatomic or alveolar Vd
Apparatus Vd:
Facemask, HME, limb of circle system if incompetent valve present
What does the alveolar compliance curve tell you?
Alveolar ventilation is a function of alveolar size and its position on the alveolar compliance curve.
The best ventilated alveoli are the most compliant (steep slope of the curve).
The poorest ventilated alveoli are the least compliant (flat portion of the curve).
perfusion is greatest at lung base due to gravity.
ventilation is best at lung base due to higher alveolar compliance.
What does the V/Q ratio represent?
The V/Q ratio is the ratio of ventilation to perfusion (minute ventilation / cardiac output).
Normal minute ventilation = 4 L/min
Normal cardiac output = 5 L/min
Normal V/Q ratio = 0.8
Dead space and shunt are absolutes. Dead space (No PERFUSION): V/Q = infinity (10/0 = infinity) Shunt (NO VENTILATION): V/Q = 0 (0/10 = 0)
V/Q mismatch occurs when the ratio is disturbed.
If the number is larger than 0.8, then this moves towards dead space.
If the number is smaller than 0.8, then this moves towards shunt.
Define the West zones of the lung.
Zone I
PA > Pa > Pv
Dead space
Ventilation without perfusion
Zone II
Pa > PA > Pv
Waterfall
Normal physiology
Zone III
Pa > Pv > PA
Shunt
Perfusion without ventilation
Zone IV
Pa > Pist > Pv > PA
Pressure in the interstitial space impairs ventilation and perfusion
Recite the alveolar gas equation.
The alveolar gas equation tells us that hypoventilation can cause hypercarbia and hypoxemia. It also explains how supplemental oxygen reverses hypoxemia, but it does nothing to reverse hypercarbia.
PAO2 = FiO2 x (Pb - PH2O) - (PaCO2 / RQ)
Pb = Atmospheric pressure PH2O = 47 mmHg RQ = Respiratory quotient = 0.8
RQ = (CO2 elimination / O2 consumption) = (200 mL / 250 mL)
Alveolar oxygen in the healthy adult patient breathing room air at sea level is ~ 105.98 mmHg.
What is the A-a gradient, and what factors affect it?
The A-a gradient is the difference between alveolar oxygen (PAO2) and arterial oxygen (PaO2).
It helps us diagnose the cause of hypoxemia by quantifying the amount of venous admixture.
It is normally 5 - 15 mmHg.
It is increased by high FiO2, aging, vasodilators, right-to-left shunting, and diffusion limitation.
List the 5 causes of hypoxemia. Which ones are reversed with supplemental oxygen?
normal A-a Gradient - reduced FIO2 & Hypoventilation
Increased A-a Gradient = DIffusion Limitation, VQ mismatch , Shunt
ALL are fixed with supplemental O2 except Shunt bc there is no way for O2 to reach pulmonary capillary .
Define the 5 lung volumes, and give reference values for each.
IRV = 3000 TV = 500 ERV = 1100 RV = 1200 CV = variable
Define the capacities, and give reference values for each.
TLC = 5800 IRV + TV + ERV + RV VC = 4500 IRV + TV + ERV IC = 3500 IRV + TV FRC = 2300 ERV + RV CC = variable RV + CV
What factors influence FRC?
FRC = RV + ERV (35 mL/kg)
Because it contains RV, the FRC can’t be measured by conventional spirometry.
Conditions that reduce FRC have several things in common. They tend to reduce outward lung expansion and or reduce lung compliance. When FRC is reduced, intrapulmonary shunt (zone III) increases. PEEP acts to restore FRC by reducing zone III.
COPD or any condition that causes air trapping increases FRC.
Why can’t spirometry measure FRC?
Because it contains RV, the FRC can’t be measured by conventional spirometry.
What tests can measure FRC?
FRC is measured indirectly by nitrogen washout, helium wash in, or body plethysmography.
What is closing volume, and what increases it?
Closing volume is the point at which dynamic compression of the airways begins. Said another way, it’s the volume above residual volume where the small airways begin to close during expiration.
C OPD L eft ventricular failure O besity S upine position E xtreme age P regnancy
mnemonic: CLOSE-P
State the equation and normal value for oxygen carrying capacity.
O2 Carrying Capacity (CaO2)
How much O2 is carried in the blood
CaO2 = (1.34 x Hgb x SaO2) + (PaO2 x 0.003)
Normal = 20 mL O2/dL
State the equation and normal value for oxygen delivery.
Oxygen Delivery (DO2) How much O2 is delivered to the tissues
DO2 = CaO2 x Cardiac output x 10
Normal = 1,000 mL O2/min
Discuss the factors that alter the oxyhemoglobin dissociation curve.
Right Shift = inc. Temp, CO2, H+, dec pH, inc 23DPG
Left Shift = HGB MET, HGB F, HGBCO,
Left = latch onto
right = release decreased affinity for O2
How is carbon dioxide transported in the blood?
Carbon dioxide is the primary by-product of aerobic metabolism. Venous blood transports it to the lungs, where it’s excreted into the atmosphere.
Mechanisms of CO2 Transport:
Bicarbonate = 70%
Bound to hemoglobin = 23%
Dissolved in the plasma = 7%
The reaction that converts CO2 to HCO3- requires the enzyme carbonic anhydrase.
c.a.
H2O + CO2 H2CO3 H+ + HCO3-
When the RBC releases HCO3- into the plasma, Cl- is transported into the RBC to maintain electroneutrality. This is called the Hamburger shift (chloride shift).
Describe the Bohr effect.
The Bohr effect describes O2 carriage.
It says that ↑ CO2 and ↓ pH cause the erythrocyte to release O2.
Conceptually, it’s the cell’s way of asking hemoglobin to release oxygen to support aerobic metabolism. ( think exercising)
