Key Calculations and Criteria for - PowerPoint Presentation

Slide1

Key Calculations and Criteria for Clinical Decision Making

Faith Rialem

Class of 2018

ObjectivesCalculations

Maintenance fluids

Winters formula

Anion Gap

Corrected QTAbsolute neutrophil count

Criteria

Centor criteria

CURB-65

HEART Score

PERC

Wells Criteria

Maintenance fluids”4

-

2

-

1” Rule1:For

0-10 kg: + 4

mL

/

kg

/

hr

For

10-20

kg

: +

2

mL

/

kg

/

hr

For

>20

kg

: +

1

mL

/

kg

/

hr

When to use: for patients who are vomiting, NPO, dehydrates, have insensible losses or third-spacing

It is important not to under-dose or overdose

Winters FormulaCalculating compensation for metabolic acidosis2

Expected P

a

C

O2= [1.5 x HCO3-] + 8 +/- 2

When to use: maximally compensates metabolic acidosis (takes 12-24 hours)3

If P

a

CO

2

is lower than expected- concomitant respiratory alkalosis

If P

a

CO

2

is higher than expected- concomitant respiratory acidosis

Anion GapAnion gap4:

=

Na

- (Cl + HCO3-)

Normal- 12Determining whether there is a gap or not helps to narrow down the differential

Metabolic acidosis differentialGap acidosis-

MUDPILES

M

ethanol

UremiaDKAP

araldehydeIsoniazid

L

actic acidosis

E

toh

/ethylene glycol

S

alicylates

Non-gap acidosis:

DURHAM

D

iarrhea

U

reteral diversion

R

enal tubular acidosis

H

yperalimentation

A

cetazolamide

M

iscellaneous

Corrected QTBazett's Formula5

=

QT Interval / √ (RR interval)

(RR interval = 60/HRWhen to use: evaluating patients with syncope, patients on QT-prolonging drugs

Absolute neutrophil countANC6

= 10

x

WBC count in 1000s x (% PMNs + % Bands)Lab test to obtain: CBC w/differentialWhen to use: assessing for neutropenic fever in chemotherapy patients and also to measure bone marrow recovery following chemotherapy.

ANC Neutropenia: ANC < 1500 cells / mm3Mild neutropenia: 1000-1500 cells / mm³

Moderate neutropenia: 500-999 cells / mm³

Severe neutropenia: < 500 cells / mm³

Centor criteria

Image credits- https://

www.mdcalc.com

/centor-score-modified-mcisaac-strep-pharyngitis#creator-insights

It is used in

patients

with recent (<3 day) pharyngitis to estimate the probability that it is

streptococcal

7

Next steps

CURB-65Estimates mortality of CAP to help determine inpatient vs outpatient treatment8

C

onfusion

1pt

U

remia (BUN >19mg/dl)

1pt

R

espiration <30/min

1pt

B

lood pressure (systolic <90 or diastolic <60)

1pt

Age

>

65

1pt

Next steps

Image credits: https://

www.mdcalc.com

/curb-65-score-pneumonia-severity#next-steps

HEART ScorePredicts the risk of a major adverse cardiac event occurring within 6 weeks

Image credits: https://

www.uptodate.com

/contents/

search?search

=heart%20score&sp=0&searchType=

PLAIN_TEXT&source

=

USER_INPUT&searchControl

=

TOP_PULLDOWN&searchOffset

=1&autoComplete=

true&language

=

en&max

=10&index=0~6&autoCompleteTerm=heart%20s

Next steps

Score

% risk

Action

0-3

0.9-1.7%

Discharge

4-6

12-16.6%

Admitted

>7

50-65%

Candidates for early invasive measures

PERCUsed to rule out PE in a low risk patient with a pretest probability >15%= score of 0

10

If any of the following are present, cannot rule out PE:

Age ≥50.

HR ≥100.SaO2 on room air <95%.Unilateral leg swelling.Hemoptysis.

Recent trauma or surgery.Prior PE or DVT.Hormone use (oral contraceptives, hormone replacement or estrogenic hormones use in males or female patients

).

Wells criteria for PEUsed to estimate the pretest probability of a pulmonary embolus11

No

Yes

Clinical signs and symptoms of DVT

0

3

PE more likely than alternate diagnosis

0

3

HR <100

0

1.5

Immobilization at least 3 days or surgery in the previous

4 weeks

0

1.5

History of prior VTE

0

1.5

Hemoptysis

0

1

Malignancy

0

1

Next steps

Image credits: https://

www.mdcalc.com

/

wells-criteria-pulmonary-embolism#evidence

Helpful ResourcesMD Calc

Epocrates

References1- Oh TH. Formulas for calculating fluid maintenance requirements. Anesthesiology

. 1980;

53:351

2-

Albert MS, Dell RB, Winters RW. Quantitative Displacement of Acid-Base Equilibrium in Metabolic Acidosis. Ann Intern Med. 1967;66:312-322. doi:10.7326/0003-4819-66-2-312.

3- M.L. Morganroth (1990) An analytic approach to diagnosing acid-base disorders.

J. Crit. Illness

5(2):138-150.

4-

Criner GJ. Metabolic Disturbance of Acid-Base and Electrolytes. In:

Critical Care Study Guide: Text and Review. 2nd ed.

Philadelphia, PA: Springer; 2010:696.

5-

Bazett HC. An analysis of the time-relations of electrocardiograms.

Heart

1920; (7): 353–37

.

6-

Al-

Gwaiz

LA,

Babay

HH. The diagnostic value of absolute neutrophil count, band count and morphological changes of neutrophils in predicting bacterial infections.

Med

Princ

Pact

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doi

:10.1159/000104806.

7-

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Decis

Making. 1981;1(3):

239-46

8-

Lim W, van der Eerden MM, Laing R, et al. Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study. 

Thorax

. 2003;58(5):377-382. doi:10.1136/thorax.58.5.377.

9-

Six AJ, Backus BE,

Kelder

JC. Chest pain in the emergency room: value of the HEART score. 

Netherlands Heart Journal

. 2008;16(6):191-196

.

10-

Freund Y, Rousseau A,

Guyot

-Rousseau F, et al. PERC rule to exclude the diagnosis of pulmonary embolism in emergency low-risk patients: study protocol for the PROPER randomized controlled study. 

Trials

. 2015;16:537. doi:10.1186/s13063-015-1049-7

.

11-

Wells PS

1

, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D, Forgie M, Kovacs G, Ward J, Kovacs MJ

. Excluding

pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer.

Ann Intern Med

. 2001 Jul 17;135(2):98-107

.