Equations

Question 1

Interstitial space deficit (hydration)

Answer 1

% dehydrated (as decimal) x BW (kg) x 1000 = mL to replace

Question 2

Maintenance Fluid Therapy

Answer 2

40 - 60 mL/kg/day

Question 3

K9 and Feline blood volume

Answer 3

K9 = 90 mL/kg
Feline = 55 mL/kg

Question 4

Resting Energy Requirement
kcal/day

Answer 4

> 2kg and < 30kg = (BW[kg] × 30) + 70 
< 2kg and > 30 kg = (70 × BW [kg])^0.75 

Question 5

Base Deficit

Answer 5

Normal HCO3 - Patient HCO3 = mEq/L

Question 6

Sodium Bicarb supplementation

Answer 6

0.3 × BW (kg) × base deficit = mEq/L

base deficit = Normal HCO3 − patient HCO3

Question 7

Anion Gap

Answer 7

(Na + K) - (Cl + HCO3) = mEq/L

Cations - Anions

Question 8

Corrected Calcium

Answer 8

Measured Ca − alb (g/dL) + 3.5 = mg/dL

Question 9

Corrected Sodium

Answer 9

Current Na +
 [(pt glucose − 100) ÷ 100 × 1.6]

Question 10

Calculated Osmolality

Answer 10

2 Na + (BUN ÷ 2.8) + (glucose ÷ 18)

Question 11

Osmolar Gap difference

Answer 11

Measured osmolality – calculated osmolality

expected osmole gap for dogs = 0 to 1 and cats = 2

Question 12

Effective Osmolality

Answer 12

2(Na) + (Glu ÷ 18)

Question 13

Total Body Water

Answer 13

0.6 x BW (kg)

Question 14

Free water deficit

Answer 14

0.6 × BW (kg) × ([current Na ÷ 140] – 1)
140 can be changed to target Na

150 for cats

Question 15

Sodium adjustment rate

Answer 15

0.5 - 1.0 mEq/hr = MAX

use with Free water deficit to calculate water supplementation over time

Question 16

Corrected Cl-

Answer 16

Measured Cl x
(Normal Na ÷ Measured Na)

Question 17

K- Max

Answer 17

0.5mEq/kg/hr

Question 18

Coronary Perfusion Pressure

Answer 18

Aortic diastolic pressure - R atrial diastolic pressure

CPP of at least 15 mmHg needed for ROSC to occur.

Pressure gradient that drives coronary blood pressure and is a surrogate for coronary blood flow.

Question 19

Cerebral Perfusion Pressure

Answer 19

MAP - ICP

Question 20

Mean Arterial Pressure (MAP)

Answer 20

CO x SVR

Question 21

Cardiac Output (CO)

Answer 21

CO = HR x SV

Question 22

Stroke Volume (SV)

Answer 22

Preload - Afterload + Contractility

CI / BW
N = 1.5–2.5 ml/beat/kg

Question 23

Systemic Vascular Resistance (SVR)

Answer 23

(MAP - CVP) ÷ CI

CI = Cardiac Index (CO / BW)

N= 0.5–0.8 mmHg/ml/kg/min

Question 24

Blood Pressure

Answer 24

Diastolic + [(Systolic - Diastolic) ÷ 3]

Question 25

Arterial Oxygen Content (CaO2)

Answer 25

(1.34 × Hb × SaO2) + (0.003 × PaO2) | SaO2 = Arterial O2 saturation ## Footnote N= 19–21 ml/dl

Question 26

Delievery of Oxygen (DO2)

Answer 26

DO2 = CO x CaO2 | ml/kg/min

Question 27

Tissue Oxygenation (Oxygen extraction)

Answer 27

VO2 ÷ DO2 | tissue O2 consumption ÷ delivery of O2

Question 28

P/F Ratio

Answer 28

PaO2 ÷ FiO2 ## Footnote N= 476 (PaO2 = 100, FiO2 = 0.21)

Question 29

Alveolar Partial Pressure of O2 (PAO2)

Answer 29

FiO2 (atm pressure - 47) - (PaCO2 ÷ 0.8) | Atmospheric pressure @ sea level 760 mmHg

Question 30

A-a Gradient

Answer 30

PAO2 - PaO2 | N= < 15 mmHg useful for room air assesment ## Footnote assessing the oxygenation ability of the lungs while removing the effects of changes in minute ventilation (PaCO2) calculated - measured

Question 31

Minute Volume (MV or Ve)

Answer 31

MV = TV x RR ## Footnote N= 150-250 mL/kg

Question 32

Tidal Volume (TV or Vt)

Answer 32

Approx 10-20 mL/kg

Question 33

Alveolar Ventilation (Va) in relation to Tidal volume

Answer 33

TV = Va + Vd | TV = sum of alveolar ventilation (Va) and anatomical dead space (Vd)

Question 34

Lung Compliance

Answer 34

C =ΔV ÷ ΔP | change in volume divided by amount of pressure applied

Question 35

Alveolar Ventilation (Va)

Answer 35

Va = (Vt - Vd) x RR | tidal volume - anatomical dead space ## Footnote control amounts of CO2 in blood

Question 36

FFP dosage

Answer 36

5-10mL/kg

Question 37

PCV transfusion calculation

Answer 37

transfused vol (mL) = BW(kg) x 90mL* x (desired PCV - pt PCV ÷ donor PCV) * or 70mL for cats* ## Footnote 1mL/kg will raise PCV by 1%

Question 38

Lean Body mass

Answer 38

Normal BW x 0.8 Obese BW x 0.7 Thin BW x 0.1

Question 39

Lactate effusion vs peripheral

Answer 39

difference of > 2mmol/L higher than peripheral suggestive of septic peritonitis | bacteria consume glucose and excrete lactate

Question 40

Glucose effusion vs peripheral

Answer 40

Difference of > 20 mg/dL lower than peripheral suggestive of septic peritonitis ## Footnote * bacteria consume glucose and eliminate lactate

Question 41

Creatine measurment of effusion

Answer 41

Fluid : serum ratio >2:1 indicates uroabdomen

Question 42

Potassium measurement of effusion

Answer 42

Fluid : serum ratio > 1.4:1 (dogs) and 1.9:1 (cats) indicates uroabdomen

Question 43

Pulse pressure (digital palpation)

Answer 43

Systolic BP - Diastolic BP

Question 44

Oxygen Index (OI)

Answer 44

MAP x FiO2 x 100 ÷ PaO2 | Lower # = better lung function ## Footnote means of evaluating oxygenation in ventilated pts

Question 45

Shock Index (SI)

Answer 45

SI = HR ÷ Systolic BP | identifier for shock, esp for early compensatory ## Footnote N = 0.37 - 0.9

Question 46

Corrected BG for polycythemia

Answer 46

BG + ([1.6 x PCV] - 81.3)

Question 47

Strong Ion Difference

Answer 47

(Na + K + Ca + Mg) - Cl - (other strong anions) | Stewarts strong Ion approach ## Footnote the difference between cations and anions in plasma

Question 48

Hematocrit

Answer 48

(MCV x RBC count) ÷ 10

Question 49

Calulated Hemoglobin from PCV

Answer 49

PCV x 0.34 ## Footnote Hb makes up approximately 1/3 of a RBC

Question 50

# Ventilation Physiological Dead Space

Answer 50

**Vd/Vt = (PaCO2 -ETCO2) / PaCo2** Normal values (dogs): <40% (spontaneous breathing), <50% (positive pressure ventilation) | Physiological dead space = anatomical dead space + alveolar dead space ## Footnote Anatomical dead space = TV of airways from nose/mouth to terminal bronchioles