Vd X Weight (kg) X [(Current Na/140) - 1]

O₂ carrying capacity of Hemoglobin

and 

O₂ carrying capacity of blood via dissolved oxygen

1.34 mL O2/g Hgb

and

0.003 mL O2/ mm Hg

Do₂ = Cao₂ X CO  X 10

(mLO₂/dL blood X L/min)

(don't need to multiply by 10 if Hgb measured in mL/L)

= TBW X (desired Na - serum Na)

then, rate of infusion (mL/hr)

= (Na requirement X 1000)/ infusate ([Na+](mmol/L) X time(hrs))

5% NaCl 855

3% NaCl 513

0.9% 154

0.45% 77

0.2% 34

Phase a - ventricular filling, diastole, Phase b - isovolumetric contraction 

Phase c - ejection, Phase d- isovolumetric relaxation

Point 1 - ventricular EDP and EDV

Point 2 - aortic valve opens, when LVP exceeds aortic diastolic pressure 

Point 3 - aortic valve closes, LV volume at this time is the ESV

Point 4 - mitral valve opens, when LVP falls below left atrial pressure 

Width of the loop - the difference between EDV and ESV = stroke volume (SV)

Area within the loop - ventricular stroke work

R = (8 X η X L)/(π X r⁴)

resistance to flow

η = viscosity

L = length

Re = 2 V r ρ/η

V = velocity

p = density of the air

r = radius of airway

When Re < 2,000, laminar flow is present

When Re >4,000, turbulent flow is present

Age (y) + 12 ÷ 2

or 

inside diameter x 3

pH >7.4

Protein <3 g/dL (<0.5 serum level)

LDH <2/3 (0.6) serum level

RBC <5,000/mm³

WBC <1000/mm³

Glucose equal to serum

pH <7.3

Protein >3 g/dL (>0.5 serum level)

LDH >2/3 (0.6) serum level

RBC >5,000/mm³

WBC >1000/mm³

Glucose less than serum

σ = 0 if there is no resistance to protein across a membrane

σ = 1 if membrane is impermeable to protein

Starling Equation

[image]

K_f is the proportionality constant

J_v is the net fluid movement between compartments

By convention, outward force is defined as positive, and inward force is defined as negative

Dosing rate

= Clearance x Desired plasma concentration

Zero order kinetics

a constant amount of drug is eliminated per unit time

phenytoin, salicylates, theophylline, and thiopentone (at very large doses)

[image]

The loading dose = the volume of distribution x the desired concentration

First Order Kinetics

A constant fraction of the drug in the body is eliminated per unit time. The rate of elimination is proportional to the amount of drug in the body; majority of drugs

 [image]

Steady State

A force or pressure change produces a proportional change in distance or volume

C_L=dV/dPtp

C_CW=dV/(P_ext-P_pl)

C_T=dV/(P_A-P_ext)

1. Specific compliance
2. Dynamic compliance
3. Static compliance

1. Compliance referenced to FRC
2. Compliance measured at peak inspiratory pressure
3. Compliance measured at plateau pressure once the chest wall has relaxed against the distention

1. Alveolar ventilation + Dead space ventilation
2. MV = V_T *RR
3. MV = V_A+V_DS

1. Closing volume plus residual volume
2. When it is above FRC, some lung segments are closed during tidal breathing

1. Sum of exploratory reserve volume and residual volume
2. Larger than V_T
3. A source of oxygen to permit ongoing pulmonary capillary gas exchange during expiration and between breaths

1. From systemic circulation
2. Supply down to terminal bronchioles
3. To systemic veins as well as pulmonary veins causing physiologic shunt
4. About 1% of cardiac output

1. Pores of Kohn -interalveolar, appear between 1y-2y
2. Lambert's channels- bronchiole-alveolar, 6y
3. Bronchiole-bronchiole channels - disease states only?

1. Time needed for a lung unit to reach 63% of its final volume
2. TC = R * C
3. Units with shorter TCs fill and empty faster than those with longer TCs

Compliance urging last 20% of inspiration

Decreases in overdistention