Pressure vs Volume control - Triangle wave - Square wave

- Triangle wave: volume control - Square wave: pressure control

Basic - Respiratory Flashcards by Nebuchadnezzer II

Why does smoking cause the hgb dissociation curve to shift leftward?

Cigarette smoke contains carbon monoxide

high affinity for hgb
Reduces 2,3 DPG

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_____ blocks commonly cause ipsilateral phrenic n block, but is not associated with significant reduction in FRC if pt has otherwise normal pulmonary function

Interscalene block

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*FRC is = to ?

ERV + RV
or
TLC - (IRV + TV)

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what is closing capacity?

The volume in the lungs during expiration when the alveoli BEGIN to close

RV (residual volume) + CV (closing volume)

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Why is FRC reduced in morbidly obese pts?

d/t decrease in ERV

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During forced exhalation, which part of the lung is emptied first? Airway closure occurs where first?

Lung apices - emptied first

Lung bases - closes first

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Lung resistance comprises of what 2 things?

Airway resistance
and
Elastic resistance

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______ resistance affects airflow into the lungs.

- Peak inspiratory pressure (PIP) directly varies with flow resistance.

Airway resistance

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______ measures resistance from the ventilator tubing to the segmental bronchi.

Peak inspiratory pressure (PIP)

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______ resistance affects expansion of the lungs. Can be thought of as pulmonary compliance
- can affect both Peak inspiratory pressure (PIP) and plateau pressure (Pplateau)

Elastic resistance

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Situations that increase airway resistance will increase _____ on the ventilator. Examples include ___

Peak inspiratory pressure (PIP)

bronchospasm
kinked ETT
mucus plug
airway secretions

*Pplateau unchanged

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Situations that increase elastic resistance (or decrease compliance) will increase _____ on the ventilator. Examples include ___

PIP and Pplateau

PTX
PNA
Pulm edema
Abdominal insufflation
Tburg
Obesity
ILD

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When does the greatest decrease in FRC occur?

Going from 60 degrees to totally supine 0 degrees

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(True/False) there is a significant decrease in FRC when changing from zero degrees to Tburg up to -30 degrees

False

unless you’re going past -30 degrees, theres no sig drop in FRC

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FRC is directly proportional to ____, and is reduced by __% in females.

height

10%

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How does positioning affect closing capacity?

it doesnt.

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Factors that affect closing capacity

COPD
CHF
Smoking
Ongoing Surgery
Age

*all alter transpulmonary pressure across airways, resulting in easier airway collapse at higher lung volume

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Pressure vs Volume control

Triangle wave
Square wave

Triangle wave: volume control

- Square wave: pressure control

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What is the mechanism behind auto-PEEP or intrinsic PEEP?

the Alveolar pressure remains positive at end-expiration

Lungs are unable to empty at end of exhalation and next breath starts
worsens gas exchange

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Why are COPD pts at increased risk for breath stacking?

Loss of elements that keep the lungs open during expiration

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After smoking cessation, how long is mucocilliary function worsened?

2 weeks

- inc sputum production

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deadspace vs intrapulmonary shunt

what is it?
which one is compromised in tburg?

deadspace: ventilation w/o perfusion

intrapulmonary shunt: perfusion w/o ventilation

*shunt is increased in t burg, no effect on deadspace

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central sleep apnea vs obstructive sleep apnea?

CSA:

brain respiratory centers do no function properly during sleep
Fail to trigger inhalation
apnea > 10s, >10x/hour

OSA:

brain fxn fine
snoring common

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Overtime, why do pts with OSA develop CSA (mixed sleep apnea)?

d/t heart failure caused by OSA

- Hypoxia/hypercapnea -> pulm HTN -> RVH -> RVF

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Pulmonary vascular resistance increases at (high/low) lung volumes. Why?

Both PVR increases at low lung volumes d/t: - as alveoli size decrease (and collapse), the geometry of pulmonary vessels surrounding alveoli bcome kinks -> resistance to flow - as lung volume decrease below nl, volume of blood in the larger pulmonary vessels dec. -> dec vessel radius -> inc resistance to flow

Tense abdominal ascites causes a (restrictive/obstructive) lung disease pattern

Restrictive | - FEV1/FVC: normal (both are reduced)

what is vital capacity?

The maximal amt of air that can fill the lungs and participate in gas exchange

In restrictive lung disease, what spirometric patterns are decreased?

``` Forced vital capacity (FVC) - amt of gas that can be forcefully and maximally exhaled from a maximal inhaled vol FEV1 FRC TLC ``` *- proportional decrease in all lung volumes

Pts with (obstructive/restrictive) lung diseases present with low FEV1/FVC

Obstructive - Decreased FEV1: airway collapse with forced exhalation - FVC: inc or unchanged

In restrictive lung disease, what happens to FEV1/FVC?

Normal | - proportional decrease in all lung volumes

Bronchospasm is (smooth/skeletal) muscle mediated

smooth muscle | - Skeletal muscle relaxants have no effect

Ways to manage bronchospasm preoperatively

1. Pretreat with corticosteroids days prior 2. Topical lidocaine 3. Albuterol

For respiratory acidosis, the pH will decrease by ___ for every acute _____ increase in PaCO2.

0.05 10mmHg

in respiratory acidosis, Bicarbonate will increase ___ and ____ for every 10 mmHg acute and chronic increase in PaCO2 *shortcut fashion

acute: 1 mEq/L chronic: 4-5 mEq/L

Most common cause of shunt in perioperative period?

Atelectasis

Pulmonary shunt is (increased/decreased) by increasing oxygen concentrations

Increased | - leads to blunting of hypoxic pulmonary vasoconstriction and microatelectasis

Which is always higher, PaCO2 or ETCO2?

PaCO2 - spontaneously breathing: 2-5 mmHg higher - ventilated: 5-10mmHg higher

What contributes to the difference btwn PaCO2 and ETCO2?

dead space ventilation - decreased cardiac output causing decreased lung perfusion - decreased lung perfusion - inc in regional lung ventilation - cardiogenic shock - PE - overinflation during PPV - High PEEP - R->L intracardiac shunt - Esophageal intubation

The lung receive innervation from the sympathetic system via ___.

T2-T7 | Parasympathetic system via vagal efferent and afferent nerves

ABG of pt w/ severe CO poisoning?

Metabolic acidosis - nl PaO2 - Falsely elevated SaO2

How does Deadspace change with positioning? Neck positioning?

Upright: increase - apex of lungs are essentially non-perfused d/t gravity Supine: decrease Extension: increase Flexion: decrease * deadspace: ventilation w/o perfusion - portion of lung not involved in perfusion (therefore, not involved in gas exchange)

Common causes of increased deadspace (5)

1. Anticholinergics 2. Bronchodilators 3. Increase pulmonary vascular resistance (emphysema and COPD) 4. Positioning (supine, neck extension) 5. Decreased Cardiac output

In ACUTE respiratory acidosis, Bicarbonate will increase ____ for every 1 mmHg increase in PaCO2 above 40 mmHg and increase ____ for every 10 mmHg increase in PaCO2

0.2 mmol/L 2 mmol/L

In CHRONIC respiratory acidosis, Bicarbonate will increase ____ for every 1 mmHg increase in PaCO2 above 40 mmHg, and increase ____ for every 10 mmHg increase in PaCO2

0.4 mmol/L 4 mmol/L

Arterial oxygen content (CaO2) equation

CaO2 = (Hgb * 1.36 * SaO2) + (0.003 * PaO2) SaO2 = % hgb saturated with O2, nl = 95%

Commonly observed capnography in pts with COPD who received single lung transplant

Double Peak - Difference btwn healthy transplanted lung, and diseased native lung - First peak: rapid exhalation of healthy, transplanted lung - Second peak: slower rate of rise of exhaled CO2 from diseased, obstructed lung

Trace nl capnogram in your head

Phase 1-2: - Beginning of expiration Phase 2-3: - Early expiration Phase 3-4: - expiratory alveolar plateau - continued exhalation of CO2 from lung alveoli Phase 4-1: sharp downstroke - inspiration

For respiratory alkalosis, for every 10mmHg decrease in PCO2, HCO3- decreases by ___ (acute), or ___ (chronic)

2 4

For respiratory acidosis, for every 10mmHg increase in PCO2, HCO3- increases by ___ (acute), or ___ (chronic)

1 4

Impairment of airflow during the EXPIRATORY phase is a result of a variable ______ airway obstruction or ____

INTRAthoracic - distal tracheal tumor - mediastinal mass - below vocal cords COPD

Impairment of airflow during the INHALATIONAL phase is a result of a variable ______ airway obstruction

EXTRAthoracic - above vocal cords - vocal cord paralysis - glottic stricture - proximal t

in pts having acute bronchospasm under GA, first line medical treatment:

beta agonist | - albuterol

Why are infants prone to bradycardia during laryngoscopy and intubation?

d/t predominance of parasympathetic nervous system

What does intubation with PEEP do to CVP, PAP, CI, and PCWP?

Increase CVP, PAP, and CI Decrease PCWP (indirect estimate of LAP) - increasing RV afterload - decreasing LV afterload

Obese individuals have decreased FRC (ERV + RV), which is reduced most?

ERV - leading to decrease in lung compliance, airway closure, and decreased PaO2 *RV is preserved

Why is morphine and atracurium not the safest choice in pts with asthma?

associated with histamine release -> induces bronchospasm

Treatment for bronchospasm if you can ventilate? What if you cant?

Can: Deepen anesthetic, inhaled B2 agonist, inhaled anticholinergics Cant: IV epi, subQ terbutaline - Mast cell stabilizer - strong B2-agonist activity

Summary of Respiratory system changes with aging: (6)

1. Decreased vital capacity 2. Increased residual volume 3. Increased closing capacity 4. Increased anatomic dead space 5. Increased lung compliance 6. Increased pulmonary vascular resistance

Why does hyperventilation lower extracellular K levels?

Hyperventilation -> lower plasma CO2 levels -> L shift in bicarb buffer system -> lowers H+ [ ] -> K+ shifts intracellularly to maintain electrical neutrality

How does Na affect MAC requirements?

Hypernatremia increases MAC req | Hyponatremia decreases MAC req

Oxygenation is solely dependent on _____ during apnea

FRC

Oxygen consumption in an adult is ____ mL/kg FRC in adult _____

3-4 mL/kg/min (adults) 7-8 (kids) 30 mL/kg

FGF must be equal to _______ to prevent rebreathing in the Mapelson A circuit. FGF must be equal to _______ to prevent rebreathing in the Mapelson D,E,F circuit.

minute ventilation 2-3x minute ventilation