Physiology Flashcards

Question

What is the relationship between compliance and elastic recoil?

Answer 1

inverse relationship - as compliance increases, elastic recoil decreases (eg. emphysema-->inflating a thin grocery bag which doesn't store much potential energy) - as compliance decreases, elastic recoil increases (eg. fibrotic lung)

Answer 2

- A chance to exhale more CO2 | - With normal breathing, we inhale more O2 than we do exhale CO2 in typical tidal breathing

Answer 3

- Having airways will decrease resistance | - Balance between decreasing resistance and minimizing dead space

Answer 4

- Exercise leads to capillary recruitment-->less alveolar dead space, no change in anatomic dead space, but overall physiologic dead space decreases

Answer 5

- More blood flow to all parts of lung since lose the effects of gravity-->less alveolar dead space - Apparently, there is also less anatomic dead space (not sure why)

Answer 6

- this describes if flow is turbulent versus laminar - as the number increases, then the flow is more turbulent - 2(radius)(density)(velocity)/viscosity - radius-->bigger airways have more turbulent flow - density-->low density gas like helium has more laminar flow (I think this is the idea behind heliox) - velocity-->if you slow down the velocity of gas with pursed lip breathing then there is more laminar flow. With exercise, there would faster velocity and more turbulent flow. (I wonder if VCD exercises would also decrease flow and turbulence)

Answer 7

- Trachea - Mainstem bronchi - The next level of bronchi (Eg. right upper lobe bronchus) - The segmental level bronchi - By the 4th generation, you are at the level of bronchioles, which don't have cartilage - Generation 4-16: bronchioles with no cartilage - Generation 16: terminal bronchiole - There are exchange units after level of terminal bronchiole (respiratory bronchiole, alveolar ducts, alveolar sacs) - Everything distal to a terminal bronchiole is called an acinus, and it's a gas exchange unit

Answer 8

- Generation 5-7

Answer 9

- at the extremes so high lung volume and low lung volume

Answer 10

- Less resistance so less resistive work of breathing | - Less compliance so increased elastic work of breathing

Answer 11

- Ppl (intrapleural pressure) is a surrogate for work of breathing - Increased work of breathing if: - Increased flow, such as with exercise - Increased resistance - Increased lung elastic recoil - With increased resistance and elastic recoil, there has to be a more negative Ppl to generate flow

Answer 12

- lower tidal volume, higher respiratory rate - lower tidal volume will decrease elastic work of breathing - even though patients need to breathe faster, there is still overall less work of breathing

Answer 13

Many pulmonary diseases result in hypoxemia (whether it's acute VQ mismatch from pneumonia or asthma or impaired diffusion from ILD). Giving oxygen will increase the pressure gradient for diffusion of oxygen, to prevent hypoxemia. Oxygen will not solve the underlying problem. There may be a very slight triggering of the respiratory drive by hypoxemia, but I don't think that's the main reason for tachypnea in these diseases. I think it's more so the changes in lung compliance and resistance that result in increased work of breathing. (Oxygen will not treat work of breathing or tachypnea).

Answer 14

- Very thin alveolar capillary layer-->high pressure will cause rupture of capillaries - pulmonary circulation is a low pressure, high capaciance system

Answer 15

- Systemic: aortic = 100 mmHg, vena cava = 2 mmg Hg | - Pulmonary: artery = 15 mmHg, vein = 8 mmHg

Answer 16

Dependent locations of the lung have better ventilation and better perfusion. (You want ventilation and perfusion to be matched as best as possible). - Although the top of the lung is actually more distended at baseline, the bottom of the lung receives more ventilation since it's at a more favorable portion of the compliance curve - Perfusion: better perfusion at the bottom (makes sense because of gravity) - West zones of perfusion: - At the top: Palveolar (surrounding pressure) > Parterial (minimal perfusion. This is not usually the case, but is relevant when there is PEEP) - Middle zone: pressure gradient depends on Palveolar - Psurrounding (there is development of an equal pressure point) - Lower zone: flow depends on Parterial - Pvenous

Answer 17

Bottom: better perfusion than ventilation (V/Q<1) Top: better ventilation than perfusion (V/Q>1)

Answer 18

- Bottom of the lung is less distended and more compliant and that's why there is better ventilation of the bottom of the lung

Answer 19

Normal PaO2 is 80-100 mmHg | Normal PvO2 is 40 mmHg

Answer 20

- ratio of CO2 production relative to oxygen consumption | - 0.8 (not a perfect 1:1 relationship; I think this is the reason for sigh breath and yawning)

Answer 21

- basically, all the mechanisms of hypoxemia, except for hypoventilation - V/Q mismatch - shunt - diffusion

Answer 22

- With exercise, there is less time available for diffusion of oxygen as a RBC moves along a blood vessel (since there is a much higher cardiac output) - In ILD, diffusion is slower because of a thicker interstitium so more likely to have desaturation - There is normal recruitment and distension of capillaries during exercise to increase surface for diffusion, but this is not possible pulmonary hypertension

Answer 23

SpO2 is the saturation as measured using a pulse oximeter. This is an estimate of the SaO2, which is measured using a blood gas.

Answer 24

ypoxemic respiratory failure (type I) is characterized by an arterial oxygen tension (PaO2) lower than 60 mm Hg with a normal or low arterial carbon dioxide tension (PaCO2). This is the most common form of respiratory failure, and it can be associated with virtually all acute diseases of the lung, which generally involve fluid filling or collapse of alveolar units. Some examples of type I respiratory failure are cardiogenic or noncardiogenic pulmonary edema, pneumonia, and pulmonary hemorrhage. Hypercapnic respiratory failure (type II) is characterized by a PaCO2 higher than 50 mm Hg. Hypoxemia is common in patients with hypercapnic respiratory failure who are breathing room air. The pH depends on the level of bicarbonate, which, in turn, is dependent on the duration of hypercapnia. Common etiologies include drug overdose, neuromuscular disease, chest wall abnormalities, and severe airway disorders (eg, asthma and chronic obstructive pulmonary disease [COPD]). Respiratory failure may be further classified as either acute or chronic. Although acute respiratory failure is characterized by life-threatening derangements in arterial blood gases and acid-base status, the manifestations of chronic respiratory failure are less dramatic and may not be as readily apparent.

Answer 25

IL5 | GMCSF

Answer 26

- Peripheral chemoreceptors are located in the carotid body and aortic arch. They primarily response to PaO2 (but they do also contribute to CO2 response) - Central chemoreceptors are located in the medullla, in a group of neurons called the retrotrapezoid nucleus. They respond to pH - The drives from central and peripheral chemoreceptors are additive

Answer 27

- Major control centre (which is the pacemaker for breathing) is in medulla and pons - Main groups of neurons: - Pre-Botzinger complex which is for inspiratory rhythm generation - Parafacial respiratory group, which for expiratory musculature control (so exhalation is usually passive from a work of breathing perspective, but surpisingly not from a control of breathing perspective)

Answer 28

- Supine position: vital capacity decrease, TLC decreases. there is no longer the depnedent effect of gravity on diaphragm and abdominal contents to increase lung volume - When unilateral diaphragmatic paralysis is present, the forced vital capacity (FVC) is usually decreased to values in the range of 70 to 80 percent of predicted, a less pronounced reduction than seen with bilateral disease. The FVC may decrease further by 15 to 25 percent in the supine position. - >10% decrease in vital capacity is associated with diaphragm weakness

Answer 29

- FVC - SVC - position: supine versus upright - after lung volume recruitment -->maximum insufflation capacity

Answer 30

Normal: - 80-90% marcophages - 5-10% lymphocytes - 0-1% eosinophils - <5% neutrophils Defining abnormal: - >3% neutrophils-->neutrophilia - >15% lymphoytes - >1% eosinophils

Answer 31

- lung is less compliant on inspiration than expiration - contributor: - changes in surfactant activity. on inflation, surfactant is less concentrated so there is more unopposed surface tension - stress relaxation, which is a general property of an elastic body - recruitment of alveoli - most important: changes in surfactant activity

Answer 32

- capillary filtration coefficient - capillary hydrostatic pressure - interstitial hydrostatic presssure - reflection coefficient - plasma oncotic pressure - interstitial oncotic pressure

Answer 33

- anemia - pulmonary vascular disease - interstitial disease - valsalve maneuver - emphsema - increased carboxyhemoglobin

Answer 34

- Venous obstruction (pulmonary venous hypertension): PVOD, pulmonary vein stenosis, left ventricular dysfunction, TGA, hypoplastic left heart - Decreased lymphatic: lymphangiectasia, superior venocaval syndrome, single ventricle physiology, tricuspid valve stenosis, failing RV, RV outflow obstruction (I think all the RV stuff is because fluid would back up into SVC) - Left to right heart shunt: ASD, VSD, PDA, partial anomalous pulmonary venous connection, systemic arteriovenous malformation, aortopulmonary connection including surgical shunt

Answer 35

- abrupt increase in systemic venous pressure post operatively, so not uncommon to have chylothorax - long term: failing fontan: Failing Fontan: - Increased systemic venous pressure: - This makes it hard for thoracic duct to empty into venous circulation - Increased hepatic and extra hepatic lymphatic production - Overwhelm resoprtive capacity of lymphatics - Consequence: lymphatic congestion, chylothorax, chylous ascites, lymphangiectasia Other complications: - Plastic bronchitis—retrograde flow from thoracic duct to parenchyma - Protein losing enteropathy Risk of systolic and diastolic dysfunction - progressive increase in systemic and pulmonary vascular resistance

Answer 36

(NEJM 2014 article) If there is a primary metabolic problem, the extent of PaCO2 compensation should be: * Acidosis: PaCO2 = 1.5 (HCO3) + 8 (+/- 2) * Alkalosis: PaCO2 = (HCO3 - 24)(0.7) + 40 (+/- 2) * Lung adapts faster than kidney so the adaptive is completed in 12-36 hours, so there is no differentiation between acute and chronic If there is a primary respiratory problem, the extent of HCO3 compensation is: * Acidosis, acute: HCO3 increases by 1, for every 10 point increase in PaCO2 above 40 * Alkalosis, acute: HCO3 decreases by 2, for every 10 point decrease in PaCO2 below 40 * Acidosis or alkalosis, chronic: HCO3 changes by 4-5, for every 10 point change in PacO2 above/below 40 (Memory trick: 1, 2, 4 for acute acidosis, acute alkalosis, chronic for either acidosis/alkalosis)

Answer 37

Adult 500 mL | Child: about 10 mL/kg (double check), be we usually ventilate at a lower volume of 5-8 mL/kg

Answer 38

- No direct connection of pulmonary veins to left atrium - Pulmonary veins connect with right sided circulation either above or below diaphragm - RA and RV tend to larger, LA and LV tend to be smaller - Mixing of oxy with deoxy blood-->shunt - Blood goes systemic through a conenction like ASD, PFO or PDA - Presentation depends on if obstruction-->pulmonary edema, pulmonary hypertension

Answer 39

- Diaphragm | - When one side is paralyzed, that side will paradoxically move up rather than down.

Answer 40

- External intercostal (inspiration is external, expiration is internal-->opposite letters) - Accessory muscles which are not normally involved: scalene (raises first 2 ribs) and sternocleidomastoid (raises sternum) (Whole thoracic cage expands in vertical, AP and lateral dimension with inspiration. There is "bucket handle" movement of the ribs.

Answer 41

- Generally no muscles are involved in expiration, except physical activity, respiratory distress or during infancy - Most important ones for active expiration are abdominal: rectus abdominus, external and internal oblique muscles, transversus abdominus - Less important: internal intercostals

Answer 42

Infants have a low FRC because the chest wall is very compliant and non-stiff. So the point at which elastic recoil is balance with chest wall recoil is at a very low volume. This is actually above below volume, so infants have to breathe above FRC - End expiratory lung volume in infants is above FRC

Answer 43

- Exhalation is ACTIVE and the end expiratory lung volume is above FRC - To avoid having the lung collapse down to FRC, they have various breaking maneuvers: - short exhalation time (they have a high RR) - active diaphragm (post inspiratory movement) - glottic adduction - When an infant is mechanically ventilated, their ability to use vocal cords to maintain end expiratory lung volume above FRC is affected, also rate is controlled-->need ot have enough PEEP

Answer 44

``` PaO2-saturation 30-60 60-90 28-50 40-75 (venous blood) 100-97 ```

Answer 45

On the oxygen hemoglobin dissociation curve, the saturation that correspond to a PaO2=50

Answer 46

When you want to unload oxygen--eg. sepsis (or think of an exercising muscle): fever, low pH, high CO2, increased 2,3 DPG (which happens with chronic hypoxia, including chronic lung diseases). There is also high DPG in anemia-->anemia will cause rightward shift The opposite of these factors causes leftward shift

Answer 47

- Leftward shift - CO has a very high affinity for Hb. So CO occupies most of the binding sites and the unoccupied binding sites bind O2 and have a very affinity so hard to unload oxygen

Answer 48

Fetal hemoglobin: left shift | Sickle cell: right shift

Answer 49

In methhemoglobin, Fe2+ on heme is changed to Fe3+, which irreversibly binds oxygen

Answer 50

100% oxygen into alveoli-->high oxygen content in blood-->create a gradient for nitrogen (which is the main gas in the entrapped air) to diffuse pneumothorax resolve faster

Answer 51

>3 cm from apex to lung | >2 cm to lateral edge

Answer 52

cardiac output

Answer 53

No, but it will increase oxygen content of the blood

Answer 54

The problem with methemoglobin: it has a significant affinity oxygen, but similarly is not able to release oxygen so blood can be oxygenated with minimal oxygen delivery (oxygen dissociation curve shifted to the left) * Congenital: generally better tolerated and patients usually asymptomatic. They have cyanosis, just because of how methemoglobin absorbs light. They have a functional anemia and there compensatory erythrocytosis. * Acquired: often drug triggered or environment related. These patients can be very sick and die, despite being given supplemental oxygen

Answer 55

Methhemoglobin and pulse ox: methemoglobin absorbs light at the two ends of the spectrum detected by the routine pulse ox, so it confuses the assessment of oxy versus deoxy blood. Having a significant amount of methemoglobin will lead to a persistent saturation of 85%, even if supplemental oxygen is given.

Answer 56

* Blood gas analyzer: * The blood gas analyzer will detect methhemoglobin by it’s absorbance at 630 nm, but other agents with similar absorbance level such as sulfhemoglobin, methylene blue and certain will interfere and cause a falsely elevated value * Co-oximeter (multiple wave length oximetry): * Absorbance is measured at a fixed wave length of 630 nm * Similar to the blood gas analyzer, other substances with a similar absorbance frequency will cause false elevation * Specialized testing (direct assay): * A reaction with cyanide (the Evelyn-Malloy method) can be used to directly measure methohemogloin, but this is a pretty specialized test and only done by speciality laboratories like Mayo Clinic

Answer 57

6 mmHg (as per Kendig)

Answer 58

Co-oximeter

Answer 59

Mixed venous blood—this is technically from pulmonary artery, but it’s often measured from central line. —>PvO2=40, saturation 73% (or could say 75% as per other sources)

Answer 60

IL4, IL5, IL13 | IL4 is important for Th0-->Th2

Answer 61

IL4, 5, 13

Answer 62

Eosinophilic

Answer 63

promotes eosinophil production from bone marrow precursor, movement out of bone marrow, recruitment to airway, growth and survival

Answer 64

- promote eosinophil apoptosis | - block the survival effect of IL5

Answer 65

- histamine | - leukotriene

Answer 66

IL10 (this is an anti-inflammatory cytokine, which is produced by regulatory T cells)

Answer 67

- Infection + cell mediated immunity | - Ctyokines: IL-2, Interferon gamma, TNF alpha

Answer 68

1/10 of systemic and furthermore, recruitment and distension enable a further drop in pulmonary resistance. (so by the time a patient develops PH, they have exhausted these mechanisms)

Answer 69

Bottom of lung since the airways are less open to start with

Answer 70

At high lung volume, low resistance of extra-alveolar vessels and high resistance of intra-alveolar vessels. (opposite for low lung volume). Total vascular resistance is lowest at FRC. (recall diagram of U shaped curve) At high lung volume, low airway resistance At low lung volume, high airway resistance

Answer 71

CCL5 (important for leaving circulation)

Answer 72

- Trigger: PAO2 (alveolar) - Threshold: PAO2 of <70 mmHg as per west (50-60 in Kendig's) - minimizes VQ mismatch

Answer 73

- Phospholipids is 80%, with the most common being phosphatidyl choline - Neutral lipids (8%), with cholesterol being the most common - Proteins (8%), like A, B, C, D

Answer 74

Static compliance = change in volume/change in pressure in the absence of flow. It consists of lung compliance and chest wall compliance. Dynamic compliance = change in volume/change in pressure in the presence of flow. Consists of: lung compliance, chest wall compliance, airway resistance (and therefore frequency)

Answer 75

As frequency increases, there is less time for alveolar units with a slow time constant (due to increased airway resistance) to fill and so they can't contribute volume to the compliance equation. In obstructive disease, there is low dynamic compliance and so the ratio of dynamic compliance/static compliance decreases as frequency increases. For normal airways, the ratio stays at 1:1 regardless of breath frequency

Answer 76

``` P = 2T/r Pressure ot inflate a lung unit T = surface tension r = radius Key point: surface tension varies depending on size of alveoli. Smaller alveoli have lower surface tension. Bigger alveoli have higher surface tension. this inverse relationship between radius and surface tension prevents significant pressure differences between the lung (that would make it unstable) ```

Answer 77

* Body pleth measures the TOTAL volume of gas in the lung, included gas trapped behind closed airway (Eg. obstructive lung disease) or pneumothorax * For a healthy subject, there wouldn’t be a significant difference in lung volume between the two methods

Answer 78

C1V1 = C2V2

Answer 79

P1V1=P2V2 on both the body and the box

Answer 80

- Inspiratory flow inadequate to trigger machine, eg. neuromuscular disease - Mask leak, which can lead to either autotriggering or ineffective inspiratory effort

Answer 81

- With the high flow-->exceed minute ventilation requirement, eliminate inspiration of room air and ilution of fiO2-->washout anatomic dead space - some positive nasopharyngeal and intrathoracic pressure at flow rate of 2 L/kg/min - reduce upper and lower airway resistance - reduces RR and work of breathing

Answer 82

- Flow rate starting at 1-2 L/kg/min-->titrate based on work of breathing - FiO2 starting at 50% -->titrate for saturations

Answer 83

- Patient already very sick - eg. high PaCO2, severe tachypnea, failure to improve after first few hours of high flow - nasal obstruction, epistaxis, severe upper airway obstruction - rare cases of air leak such as pnemo - in hypovolemic patients-->can be sensitive to increased intrathoracic pressure and increased PA afterload

Answer 84

- High frequency relative to normal breath sounds - Normally heart at C7 to T3, but they can be pathologically present when there is airspace disease and alveoli can't do their normal function of filtering out frequency sounds - Other signs of alveolar disease (eg. consolidation): whispering petroliloquoy (increased loudness of whispering), egophany - compared to normal breath sounds, the I:E ratio is 1:2 versus 3:1 and distinct pause between inspiration and expiration (hollow, high pitched) normally, speech sounds and bronchial breath sounds are filtered, but this is not the case with airspace disease

Answer 85

- Graph of transpulmonary pressure versus volume - Dynamic compliance: hysteresis curve - Static compliance: straight line - Resistance = the difference between the 2 curves

Answer 86

1% = 10 mg/mL 2% = 20 mg/mL Maximum dose is 4 mg/kg S/E: seizures from lidocaine toxicity

Answer 87

complications of bronchoscopy: * Death is very uncommon, though at least 1 death in a paediatric patient has been reported * Not obtaining the right answer or therapeutic result (procedure failure) * Greater risk of traumatizing mucosa with rigid than flexible bronchoscopy since the rigid has a larger diameter and is more rigid * Mechanical complications: * Due to direct trauma to the airway, such as pneumothorax, mucosal oedema, hemorrhage. This is more likely with forceps or trans bronchial biopsy * Epistaxis is a risk if trans-nasal approach in patients with thrombocytopenia * (Orotracheal will avoid contamination of lower airway specimens with upper airway bacteria in patients who are immunocompromised)—>good to see that Kendig’s directly endorses this * What is the mechanism for pneumothorax in the absence of trans bronchial biopsy? * When ventilating through an ETT with flexible scope in place: easy to get air in around the tube on inspiration, but on expiration it’s hard to get the air out (since exhalation is passive) * Increased intrapulmonary pressure—>decreased pulmonary perfusion or pneumothorax * Physiologic complications: * The scope obstructs the airway to some extent—>hypoxia, hypercapnia * Inadequate sedation/anaesthesia—>cardiac arrhythmia * Not enough topical anaesthesia (this is often applied by the bronchoscopist at carina or cords)—>laryngospasm or bronchospasm * Lidocaine toxicity—>seizures * Bacteriologic: * Infection in one part of lung could be spread to another part * Risk of bacterial endocarditis in some patients—>but give antibiotic prophylaxis AFTER BAL sample is obtained * Risk of infection to bronchoscopy team, eg. in patient with cavitary TB—>administer treatment first, before bronchoscopy, to reduce risk * Cognitive risks: * failure to obtain useful information * failure to make the right diagnosis * failure to do a bronchoscopy when it’s the only way of obtaining information * helpful to record bronchoscopy to review, revise diagnosis, teaching, research

Answer 88

Normal: - 80-90% marcophages - 5-10% lymphocytes - 0-1% eosinophils - <5% neutrophils Defining abnormal: - >3% neutrophils-->neutrophilia - >15% lymphoytes - >1% eosinophils

Answer 89

- Hypersensitivty - Sarcoid - Mycobacterial infection

Answer 90

Physical exam, spirometry, CXR | - Exercise challenge and bid PEF if asthmatic

Answer 91

* Contraindications to diving: * Blebs or cysts * Cystic fibrosis * Fibrotic lung disease * Spontaneous pneumothorax without having had bilateral pleurodesis + normal lung function and thoracic CT post * Traumatic pneumo is ok if healed, normal spirometry and CT scan * Active sarcoid * Active TB * Contraindications for asthmatic patient to dive if not: * Free of asthma symptoms * Asthma not triggered by cold, emotion or exercise * Normal spirometry * Negative exercise challenge (<15% drop in FEV1 at end of test) * At the time of the dive: * Can’t required relievers in 48 hours leading up to dive * Need to do BID monitoring of PEF. If >10% drop from baseline leading up to dive or >20% diurnal variation, then not advised to dive

Answer 92

- VO2 max low for total body weight, but normal for ideal body weight - Normal O2 pulse - Early peaking of HR (more steep slope) - Reduced or normal anaerobic threshold - Normal breathing reserve, but can have expiratory flow limitation (pseudo asthma) since they breathe close to residual volume at rest - Normal gas exchange

Answer 93

- VO2 max is low - Low O2 pulse - Normal HR max - Low anaerobic threshold - Normal breathing reserve - Normal gas exchange

Answer 94

- Derived from the multiple breath washout test - Number of lung turnovers required for the end-tidal tracer gas concentration to reach 1/40 of it's original concentration - Higher LCI is bad -->means more heterogeneity/inhomogeneity - Two gases: N2 or SF6 - Cumulative expired volume/FRC - LCI is <7 lung turnovers in children

Answer 95

- More sensitive marker of small airway obstruction and is especially useful for early CF, where the distal airways are more obstructed and spirometry is normal Advantages: technique is harmless, easy for patients to perform and reproducible, even in infants and small children. Being non-invasive, it is repeatable on multiple occasions, increasing its longitudinal applicability.

Answer 96

- Concentrator manufactures oxygen by concentrating air, so smaller, more portable, don't need to refill, but do need to have good power source, back up battery/generator, and access to oxygen cylinders - Cylinder is literally oxygen

Answer 97

either concentrator or cylinder. For flow rate <1 L, consider use of a low flow meter. If low flow at <0.3 L/min for a short duration, then consider use of cylinder

Answer 98

- Elderly since there is low elastic recoil and so low intrapleural pressure to start off with (minimal traction on airway to keep them open) - Infants since they have a low residual volume (high elastic recoil, low chest wall recoil) - High airway resistance (if the airway is narrow, it will close sooner)

Answer 99

(Regional Differences in Ventilation and Closing Volume - Exam)

Answer 100

0.3 (age) +4

Answer 101

>3-5% saturation difference or >20 mm Hg PaO2 difference between pre (right arm) and post ductal (any leg). Causes: - PPHN - obstructive left sided disease like HLHS, coarctation, interrupted aortic arch

Answer 102

- decreased FRC - decreased ERV (expiratory reserve volume) since FRC is decreased, but normal residual volume - In mild obesity, the spirometry is normal, but as BMI increases you will then see restriction with decreased FEV1, decreased FVC. They are proportionately decreased so FEV1/FVC ratio is stable. - With severe to morbid obesity, there is airflow obstruction. Lower lung volumes may result in earlier airway closure. - Key point: when the lung is restriction, the lung is at less favourable location on compliance curvemore work of breathing

Answer 103

They can fly 7 days post CXR showing radiologic resolution. 2 week delay post normal CXR for patients with CF. (Patients with pre-existing lung disease who have a secondary pneumothorax with pleurodesis-->increased risk of recurrent pneumothorax for at least 1 year (maybe longer).

Answer 104

- High elastic recoil - Relatively large airways for lung volume - (Inadequate coaching) - restrictive lung disease, regardless of age, will result in high elastic recoil

Answer 105

Falsely low PaO2 (since gas diffusion through syringe and consumption of oxygen by leukocytes). Sample needs to be put on ice and analyzed within 15 minutes

Answer 106

Falsely low PacO2 and low pH (looks like metabolic acidosis with respiratory compensation)

Answer 107

If air bubbles are >1-2% of volume, then high PaO2, low PaCO2 (so the sample will look better than it is)

Answer 108

Qf = Kf[(Pc − Pis) − σ(πpl − πis)] where Qf = net flow of fluid Kf = capillary filtration coefficient; this describes the permeability characteristics of the membrane to fluids and the surface area of the alveolar-capillary barrier Pc = capillary hydrostatic pressure Pis = hydrostatic pressure of the interstitial fluid σ = reflection coefficient; this describes the ability of the membrane to prevent extravasation of solute particles such as plasma proteins πpl = colloid osmotic (oncotic) pressure of the plasma πis = colloid osmotic pressure of the interstitial fluid

Answer 109

Central - responds to CO2, located in brainstem | Peripheral - responds to CO2 and O2, located in carotid body and aortic body (aortic arch)

Answer 110

From CPS statement: - Higher flow rate enables delivery of higher concentration of oxygen since it exceeds minute ventilation requirement. Since the gas is heated and humidified, the higher flow rate is better tolerated - Positive intranasal and intrathoracic pressure during exhalation when a higher gas flow of 2 L/kg/min is used - Reduces upper and lower airway resistance - Washout of anatomic dead space reduces work of breathing Other: - humidification prevents airway dessication and secretion removal

Answer 111

- Guillan barre - polio - Enterovirus D68 - botulism, myasthenia gravis - mechanisms of causing lung disease: hypoventilation, aspiration, secondary infection, guillian barre can cause autonomic neuropathy-->cardiac failure-->pulmonary edema

Answer 112

Hypoxic pulmonary vasoconstriction to minimize shunt. | VQ mismatch is the main cause of hypoxemia in acute respiratory disease

Answer 113

Hypoxic pulmonary vasoconstriction

Answer 114

pH: low pH-->increased vasoconstriction. High pH-->decreased vasoconstriction Hypercapnea increases pulmonary vascular resistance. (The effect of pH is independent of PCO2) Low temperature decreases pulmonary vascular resistance. Hyperthermia increases HPV Age: high HPV at birth and during infancy, but then response declines Iron: increased HPV if low iron (so especially important to ensure that infant with BPD and pH has normal iron)

Answer 115

- all saturations <70% are NOT accurate - abnormal Hb such as HbS, COHb, methemolglobin - non-pulsatile flow - eg. poor perfusion, VAD

Answer 116

- CO has 240 times the affinity for Heme as oxygen does-->limit oxygen binding - Causes leftward shift of oxygen hemoglobin dissociation curve-->bound oxygen can't be unloaded - Also affects tissue utilization of oxygen

Answer 117

History + elevate CO hemoglobin (as quantified based on co-oximetry) - you need to do co-oximetry of the blood gas sample

Answer 118

>=11-12% (makes sense since 10% is considered significant for CF patient and 12% is significant for BD response)

Answer 119

Non-smoker: 3% | Smoker: 10-15%

Answer 120

(VA) (pulmonary capillary blood volume) Hb)/ (alveolar capillary thickeness x COHb)

Answer 121

Conditions where there is restriction, but normal lung parenchyma, such as obesity and neuromuscular disease. (all other conditions would NOT have a normal DLCO when applying this correction)

Answer 122

If there is active bleeding, then DLCO increases. Presence of Hb in the alveoli will take up CO, thus increasing it's diffusion. (For other types of hemorrhage or if remote pulmonary hemorrhage with low Hb-->lower DLCO)

Answer 123

Increased DLCO since there is increased pulmonary capillary blood volume Maneuver : forced expiration, then inhalation, the maneuver is used to figure out the cause of OSA

Answer 124

Cytokine is a general term used for all signaling molecules while chemokines are specific cytokines that functions by attracting cells to sites of infection/inflammation.

Answer 125

17-20 mL/dL of oxygen

Answer 126

Bottom of the lung (more dependent portion) receives a greater proportion of ventilation. Due to gravity, the intrapleural pressure is more negative at top of lung and less negative at bottom of lung. Alveoli at top of lung are more distended and have a greater baseline volume than alveoli at bottom of lung. Alveoli at bottom of lung are on a more favorable portion of the compliance curve. This same principle re: difference between dependent and non-dependent region holds true regardless of lung position (Eg. upright versus decubitus)

Answer 127

i. Foreign body removal ii. Assessment of posterior trachea (e.g., tracheoesophageal fistula) and larynx (e.g,. laryngeal cleft)

Answer 128

i. Limited ability to access more distal areas of the lung, and those requiring a flexible curve to reach, e.g., right upper lobe ii. Limited ability to obtain bronchoalveolar lavage specimens

Answer 129

Surface area x diffusion coefficient x P1-P2 divided by thickness of diffusion barrier Diffusion coefficient depends on solubility and molecular weight

Answer 130

- asthma | - complete the rest of this answer

Answer 131

- With aging, the lung is more compliant, but there is lower elastic recoil. (the lung is easier to inflate, but there is less stored potential energy). This would be similar to emphysema - Since there is decreased static recoil, there is increased FRC - closing volume is higher and might exceed FRC - lower muscle strength leads to higher residual volume - decreased DLCO due to surface area and pulmonary capillary blood volume - stiffening of the chest wall-->less compliant - because of higher closing volume, even at FRC the patient may be ventilating just the top of the lung, perfusion needs to match these changes - basically aging sucks

Physiology Flashcards

(163 cards)