PP semester cards Flashcards
Upper Inflection point (UIP)
- Point on the P-V curve where compliace deteriorates at high pressure
- Keep the PIP below the UIP to prevent high pressure
normal value of airway resistance
0.6-2.4 cm H2O
19 (alveolar ducts, 0.5 mm)
cilia disappear
Static compliance equations
Vt/(Pplat-PEEP)
Fast twitch glycolytic fibers
good for brief periods of high work load (high strength, poor endurance)
Surfactant
- Decrease ST
- Keeps Alveoli Stable
- Decreases WOB
- increases lung compliance
Metabolic WOB
the amount of O2 consumption by the ventilatory muscles while the muscles perform a certain tasked compared to the total VO2 of the body.
Resistance formula
(Pmax-Plat)/Flow
Canals of Lambert
Bronchiole-Alveolar
Airway functions
- Filter
- Warm
- Humidifying
- Air conduction
- Phonation and smell
conditions resulting in decrease amounts of surfactant
- Pulmonary embolism
- Shallow breathing
- newborn respiratory distress syndrome
- ARDS
14 (Bronchioles)
no goblet cells and cells become cuboidal
Airway resistance equation
Vt/(PiP-PEEP)
10-11 generation (Bronchioles, 1 mm)
Cartilage disappears
what are the components of mechanical WOB?
- Pressure loads
- Volume Loads
- Flow Loads
Laminar flow is determined by
Viscosity
Formula for Compliace
clt= Vt/(Pplat-peep)
Normal values are 50-100 mL/cm H20
Consequences of surfactant deficiency
- stiff lungs
- Atelectasis
- fluid filled alveoli
- increase WOB
in work of breathing when resistance increases
Slanted resistance Pressure volume loop
Two Factors of Alveolar Stability
- Critical opening pressure
- The pressure at which the collapsed respiratory zone of the lung *ALVEOLI* open
- Critical closing pressure
- The pressure at which the unstable respiratory zone of the lung *alveoli* collapse
- COP > CCP
P0.1 (P100) normal value and why we measure it?
Normal Value is -2 to -5 cm H2O
- 1 would indicate a low central drive to breath
- 6 would indicate a high central drive to breath
Nasal Passages
- Turbinates- 3 Bony projections in the nasal cavity, increases surface area
- Meati- passageways resulting from the bony projections
- Nasal Septum- often defects left, possibly making the right side more accessible for catheters
17 (respiratory bronchioles)
smooth muscle starts to thin out and disappear
Time constant is ?
Amount of time needed to fill or empty 63% of the lung. Actual time varies according to regions resistance and compliance.
Conductance
The capability of system to maintain flow
23-24 (alevoli)
squamous cells
Text book values of compliace
Lung compliance = 200 mL/cm H2O
Thorax compliance= 200 mL/cm H20
CLT= 100 mL/cm
Turbulent flow is determined by
Density
increase compliance will result in
a more vertical pressure volume loop
Pores of Kohn
Inter-alveolar
two sources of increased fatigue?
Decreased supply and increased demand
decreased compliance is seen in?
- Tension Pneumothorax
- Mainstem intubation
- ARDS
- Pleural effusion
- Atelectasis
- Pulmonary edema and CHF
- Lung resection
- Lung consolidation
- Hyperinflation
- Pulmonary Fibrosis
- Pneumonia
Channel’s of Martin
Interbronchiole
Pendelluft
air moves from one area of lung to another
Increase compliance
- Flail Chest
- Elderly
- Emphysema
slow twitch oxidative fibers
55% of fibers, use in quiet breathing (good endurance, modest strength)
Factors that prevent atelectasis
- Collateral Ventilation
- Surfactant
- interdependance of lung units
Dynamic Compliance equation
Vt/(pip-peep)
Work of breathing in a healthy human
- Tissue (viscous)- non-elastic resistance
- 7% of WOB
- Compliance- Elastic Resistance (Static Compliace)
- 65% of WOB
- Airflow resistance- Non Elastic resistance (Dynamic Compliance)
- 28% of WOB
what is equal pressure point?
point along the airway where pleural pressure equals the pressure inside the airways. Pleural pressure exceeds airway pressure, the airway will be compressed and flow will be hindered. Large airways have cartilage to prevent collapsing.
Lower inflection point
theory is to open alveoli and then set PEEP above CCP to prevent alveolar collapse
*preventing shear stress injury - the repetitive opening and closing of alveoli also known as atelectrauma*
Vt=
VD+VA
V̇E=
(VT is known)
Vt x f
V̇D=
VD x f
V̇A=
VA x f
V̇E=
V̇A + V̇D
PACO2≈
VCO2/VA
Ventilation
- Movement of air into and out of the lungs
- The effectiveness of ventilation is measured by assessing PaCO2
PAO2=
PaO2
Dead Space definition
- Ventilation (V) without Perfusion (Q)
- Ventilation without adequate perfusion
- Wasted Ventilation
- Re-breathed CO2
Physiologic Dead Space
- Anatomic in the conducting airways
- Alveolar in the alveolar region of the lung
- relative VD, VD effect ( ventilation without adequate perfusion)
- Mechanical deadspace is re breathed gas outside the airway; ventilator, mask
anatomic dead space
- approximates 1 ml/ lb ideal body weight
- 2 ml/Kg body weight
- Measured by the Fowler’s Method
Calculate physiologic dead space by the Bohr equation
VD/Vt= (PaCO2 -PeCO2)/PaCO2
Bohr equation if Vt is known
VD={(PaCO2-PECO2)/PaCO2] Vt
Normal Value based off the Bohr Equation
0.2-0.4
causes of increased VD/VT
- Pulmonary Embolism ( ↑ VD
- Positive pressure breathing ( ↑VD)
- Tachypnea ( ↓ Vt)
- Decreased Pulmonary Blood flow ( ↑VD, VD effect*)
*Ventilation without adequate perfusion*
causes of decreased VD/VT
- Endotracheal tube ( ↓ VD)
- Large tidal volumes ( ↑Vt)
- Exercise
- During exercise, VD/VT decrease
- VD increases but Vt increases much more
- ↑VD/ ↑ ↑ ↑ Vt)
causes of increased VE (in patients with normal PaCO2)
PaCO2 ≈ VCO2/VA
increased VD
increased VCO2
Desired VE
required VE= actual VE * (Actual PaCO2/ Desired PaCO2)
Nutritional support
- Preserve lean body mass
- Replace vitamins and minerals
- increased muscle strength and edurance
- prevents muscle breakdown
- maintain ventilatory chemosensitivites
- preserve immune fuction
- promote wound healing
complications of malnutrition
- Altered cell-mediated immunity
- Tissue atriophy and poor wound healing
- malabsorption and anemia
- ↓ Hypoxic ventilatory response
- ↓ surfactant production
- ↓ability to wean from MV
- ↓ pulmonary bacterial clearance
- ↓ colloid osmotic pressure
Effects of overfeeding
- ↑ metabolic rate
- ↑ VO2
- ↑ WOB from ↑ VCO2
- ↓ ability to wean from MV
- extra weight
N2 in subtracted by N2 out= ?
N2 Balance
24 hr urine urea N2 is needed
why should we maintain a positive nutrition?
growth (anabolic state)
why should we avoid negative balance?
tissue destruction (catabolic state)
explain what indirect calorimetry is?
an indirect measurement of calorie consumption by measuring VO2 and VCO2 which are functions of metabolism
*indirect calorimetry becomes more inaccurate at FIO2s greater than 60% (Haldane Transformation)
How do we calculate VO2 at STPD?
(FIO2-FEO2) * VE
*Converte BTPS to STPD by multiplying by .82*
How do we calculate VCO2 at STPD?
FECO2 x VEstpd
what is the normal value for VO2?
0.25 L/min
what is the normal value for VCO2?
0.20 L/min
what is RQ? and why do we replace it with RER?
respiratory quotient (internal respiratory) is difficult to measure and invasive. RER is respiratory exhange ratio measures exhaled gas concentrations, is less invasive and is a substitue for RQ
Low RQ is ?
- Starvation
- Hypoventilation
- Alcohol consumption
- ketone formation
High RQ?
- hyperventation
- Metabolic acidosis
- during exercise
what is the Weir equation?
REE= [(3.94 x VO2) + (1.11 x VCO2)] x 1440
what determines lung volumes?
- Height
- Gender
- Age
- Race
what is multi-breath closed circuit technique?
Helium dilution
- rebreath a known helium concentration until it stabilizes.
why do we use helium?
- inert- doesnt react with other compounds and is nontoxic
- not present in the normal lung- easy to be be traced
- low density to penetrate into poorly ventilated areas
- very little dissolves in body tissue- little is lost from the system
what is multi-breath nitrogen washout?
multi-breath open circuit N2 washout test
breaths 100% O2 for several minutes
all exhaled gas is collected
the test is complete when the exhaled nitrogen level drops to 1.5%
Enteral feeding is?
by mouth( intestine), Total enteral nutrition (TEN)
Parenteral feeding is?
by I.V., hyperalimentation, total parenteral nutrition (
what is ATP?
adenosine Triphosphate
breaking down of ATP to ____ yields ____
breaking down of ATP to ADP yields energy
while muscles work?
ATP breakdown is contant and must be replaced as fast as it is used if the muscle is to continue to work.
The anaerobic process yields …
2 ATP/M of Glucose
Can power system indefinitely
yields 36 ATP/M of glucose, training increases the number of mitochondria, which increases the ability to use oxygen, will increase endurance and strength.
untrained muscles have few capillaries and mitocondria. Can these conditons be improved?
both conditions can be improved with endurance training
what does oxygen debt mean?
volume of oxygen that is “missing” in the first few in minutes of acute increases in work.
borrowing oxygen and repaying it.
increased work till maximum tolerance is reached
that point is known as VO2 max- The oxygen uptake per minute at a given.
what is the list of indications for cardio-pulmonary exercise testing?
- Evaluation of unexplained dyspnea
- Evaluation of exercise toleranance
- Evaluation of patients with specific diseases
- Evolving role in overall assessment of CHF
- Useful indicator in timing of heart transplantation
- preoperative evaluation
contraindications to exercise testing list
- recent MI (within four weeks)
- unstable angina
- 2nd and 3rd degree heart block
- rapid arrhythmias
- many other cardiac cardiac condictions
- PaO2 < 40, PaCO2 > 70
- FEV1 < 30%
VD/VT=
(PaCO2-PeCO2/PaCo2)
VD=
(PaCO2-PeCO2/PaCo2) VT
