Pediatric and Adult Weight Based Calculations

Transcription

PEDIATRIC AND ADULT DOSAGE
CALCULATION BASED ON WEIGHT
Mosby items and derived items © 2014, 2010, 2006, 2002, 1998, 1994 by Mosby, Inc., an imprint of Elsevier Inc.
DOSAGE CALCULATION BASED ON
WEIGHT: OBJECTIVES
AFTER REVIEWING THIS CHAPTER, YOU SHOULD BE ABLE TO:
1. CONVERT BODY WEIGHT FROM POUNDS TO KILOGRAMS
2. CONVERT BODY WEIGHT FROM KILOGRAMS TO POUNDS
3. CALCULATE DOSAGES BASED ON MILLIGRAMS PER KILOGRAM
4. DETERMINE WHETHER A DOSAGE IS SAFE
5. DETERMINE BODY SURFACE AREA (BSA) USING THE WEST NOMOGRAM
2
DOSAGE CALCULATION BASED ON
WEIGHT: OBJECTIVES (CONT’D)
6. CALCULATE BSA USING FORMULAS ACCORDING TO UNITS OF
MEASURE
7. DETERMINE DOSAGES USING THE BSA
8. CALCULATE THE FLOW RATES FOR PEDIATRIC IV THERAPY
9. CALCULATE THE SAFE DOSAGE RANGES AND DETERMINE NORMAL
RANGE FOR MEDICATIONS ADMINISTERED IV IN PEDIATRICS
3
BACKGROUND
• FROM COHEN, M. (2010):
• ERROR RATE IN CHILDREN IS 3 TIMES HIGHER THAN IN
ADULTS
• CONFUSION BETWEEN ADULT AND PEDIATRIC
FORMULATIONS
• ORAL LIQUIDS AVAILABLE IN MULTIPLE PEDIATRIC STRENGTHS
• INCORRECT DILUTION OF MEDICATIONS
• LOOK-ALIKE PACKAGING, LOOK-ALIKE NAMES, SOUNDALIKES
• IMPROPER EDUCATION OF PARENTS
• CALCULATION ERRORS
• ERRORS IN MEASURING DEVICES (HOUSEHOLD VS. METRIC)
4
BACKGROUND (CONT’D)
• MAKE SURE DOSAGE IS SAFE.
• PHYSIOLOGICAL CAPABILITIES ARE DIFFERENT IN INFANTS AND
CHILDREN THAN IN ADULTS
• TWO METHODS TO CALCULATE PEDIATRIC DOSAGES:
• BODY WEIGHT (BW)
• BODY SURFACE AREA (BSA) BASED ON HEIGHT AND WEIGHT
• NURSE RESPONSIBLE FOR VERIFYING BEFORE GIVING
5
BACKGROUND (CONT’D):
SAFETY ALERT
AS THE NURSE ADMINISTERING MEDS TO CHILDREN, YOU
ARE LEGALLY RESPONSIBLE FOR RECOGNIZING INCORRECT
AND UNSAFE DOSAGES AND FOR ALERTING THE
PRESCRIBER.
6
PRINCIPLES RELATING TO
BASIC PEDIATRIC CALCULATIONS
1. USE SAME METHODS (R&P, DA, FORMULA)
2. PEDIATRIC DOSES ARE SMALLER (IN MCG)
3. IM DOSAGES RARELY EXCEED 1 ML; FOR SMALL INFANTS, 0.5 ML
4. SUBCUT DOSAGES ARE NOT TO EXCEED 0.5 ML
5. FOR DOSAGES LESS THAN 1 ML, USE TB SYRINGE
6. PEDIATRIC DOSES ARE RARELY ROUNDED TO TENTHS; USE TB SO
HUNDREDTHS CAN BE GIVEN
7. ALL ANSWERS MUST BE LABELED
8. KNOW INSTITUTION POLICY ON ROUNDING DOSAGES
7
CALCULATION OF PEDIATRIC DOSAGES
BASED ON BODY WEIGHT
• COMPARE ORDERED DOSAGE TO RECOMMENDED SAFE DOSE RANGE
• POUNDS TO KILOGRAMS (2.2 LB = 1 KG)
• TO CONVERT POUNDS TO KG, DIVIDE POUNDS BY 2.2
• TO CONVERT KG TO POUNDS, MULTIPLY KG BY 2.2
• EXAMPLE 1: CONVERT CHILD’S BW OF 30 LB TO KG
8
DIMENSIONAL ANALYSIS (DA)
9
CONVERTING POUNDS/OUNCES TO KG
1. CHILD WEIGHS 14 LB 6 OZ. CONVERT TO KG.
10
CONVERTING POUNDS/OUNCES
TO KG (CONT.)
11
. 1998, 1994 by Mosby, Inc., an imprint of Elsevier Inc.
Mosby items and derived items © 2014, 2010, 2006, 2002,
• CONVERT 14.4 LB TO KG
SAFETY ALERT
Use caution when
converting ounces to a
fraction of a pound.
Remember to add the
remaining whole pounds
to get the total pounds
before converting to
kilograms.
12
CASE STUDY 6
TARA BATES IS YOUR 4-YEAR-OLD PATIENT ADMITTED TO THE PEDIATRIC
UNIT WITH MRSA INFECTION TO THE RIGHT INNER THIGH WITH PLANS
FOR I AND D TOMORROW MORNING. YOU WEIGH TARA AND FIND
SHE IS 32 LB AND 9 OZ. YOU MUST CONVERT THE WEIGHT TO KG
WHEN FILLING OUT THE SURGICAL CHECKLIST. WHAT IS TARA’S
WEIGHT IN KG?
13
CASE STUDY 6 (CONT.)
ANSWER:
TARA WEIGHS 14.8 KG.
14
CONVERTING GRAMS TO KILOGRAMS
• NEONATES ARE WEIGHED IN GRAMS
• 1,000 G = 1 KG
• CALCULATE WEIGHT OF 3,000 G INFANT IN KG
15
16
REVIEW OF CONCEPTS
• CONVERT THE CHILD’S WEIGHT IN KG—ROUND TO 10TH
• RECOMMENDED DOSAGE—REPUTABLE SOURCE
• TOTAL DAILY DOSAGE—AMOUNT ALLOWED IN A 24 HOUR PERIOD
• DIVIDED DOSES—AMOUNT OF DRUG FROM TOTAL DAILY DOSE
DIVIDED INTO VARIOUS INCREMENTS
17
REVIEW OF CONCEPTS (CONT.)
• SAFE DOSE—HIGH AND LOW RANGES OF RECOMMENDED VERSUS
WHAT IS ORDERED
• CALCULATE SAFE DOSE BY MULTIPLYING WT BY RECOMMENDED
DOSE—ROUND TO 10TH
• COMPARE THE ORDERED DOSE TO THE RECOMMENDED DOSE AND
DETERMINE IF THE DOSAGE IS SAFE
• IF SAFE, CALCULATE THE AMOUNT AND ADMINISTER
• IF UNSAFE, NOTIFY THE PRESCRIBER
18
REVIEW OF CONCEPTS (CONT.)
SAFETY ALERT
BEFORE ADMINISTERING ANY MEDICATION TO A CHILD,
ALWAYS ASK YOURSELF IF THE DOSAGE IS SAFE. WHEN IN
DOUBT, CONTACT THE PRESCRIBER BEFORE ADMINISTERING.
PEDIATRIC MEDICATIONS SHOULD ALWAYS BE CHECKED BY
TWO NURSES.
19
SINGLE-DOSE MEDICATIONS
20
SINGLE-DOSE MEDICATIONS (CONT.)
21
SINGLE-DOSE RANGE MEDICATIONS
• SOME MEDICATIONS CAN INDICATE A MINIMUM AND A MAXIMUM
RANGE
• EXAMPLE 2: VISTARIL 15 MG IM Q4H PRN NAUSEA
CHILD WEIGHS 38 LB. IS THE DOSAGE SAFE?
RECOMMENDED DOSE: 0.5 TO 1 MG/KG/DOSE Q4H
2.2 LB: 1 KG = 38 LB: X KG
X = 17.3 KG
22
SINGLE-DOSE RANGE MEDICATIONS (CONT.)
23
SINGLE-DOSE RANGE MEDICATIONS
(CONT.)
24
YOU CONTINUE WITH YOUR ASSESSMENT OF TARA AND NOTICE THAT
SHE FEELS WARM TO THE TOUCH AND HER CHEEKS ARE FLUSHED. AN
ORAL TEMPERATURE REVEALS A FEVER OF
101.5 ° F. YOU REVIEW
THE CHART AND FIND THE FOLLOWING ORDER:
TYLENOL ELIXIR (160 MG/5 ML) 150 MG PO Q4H PRN FEVER > 99° F
THE SAFE DOSE RANGE READS:
10-15 MG/KG/DOSE Q4-6HR AS NEEDED.
IS THE DOSE SAFE? (TARA WEIGHS 14.8 KG) IF SO, HOW MUCH WILL
YOU ADMINISTER?
25
ANSWER:
THE DOSE IS SAFE, ADMINISTER 4.7 ML AFTER CHECKING
CALCULATIONS AND DOSAGE WITH ANOTHER NURSE.
26
PEDIATRIC DAILY DOSAGES
1. CALCULATE TOTAL DAILY DOSAGE
2. DIVIDE DAILY DOSAGE BY NUMBER OF DOSES TO BE ADMINISTERED
3. USE R&P, FORMULA METHOD, OR DA TO CALCULATE NUMBER OF
TABS OR CAPS OR ML TO ADMINISTER THE DOSE
27
PEDIATRIC DAILY DOSAGES (CONT.)
ORDER: DILANTIN 30 MG P.O. Q8H. CHILD WEIGHS 18 KG.
RECOMMENDED DOSAGE IS 5 MG/KG/DAY IN TWO OR
28
THREE EQUALLY-DIVIDED DOSES. IS THE DOSAGE SAFE?
PEDIATRIC DAILY DOSAGES (CONT.)
1. CALCULATE SAFE TOTAL DAILY DOSAGE:
5 MG/KG/DAY X 18 KG = 90 MG PER DAY
2. DETERMINE AMOUNT FOR EACH DOSE (3):
30 MG Q8H = 30 MG THREE TIMES DAILY
30 MG × 3 = 90 MG DAILY; THEREFORE IT IS SAFE
29
ADULT DOSAGES BASED ON
BODY WEIGHT
• INFORMATION USED TO CALCULATE DOSAGES FOR CHILDREN CAN
ALSO BE USED FOR ADULTS
EXAMPLE 3:
ORDER: TICAR 4 G IV Q6H. CLIENT WEIGHS 175 LB.
RECOMMENDED DOSE IS 200 TO 300 MG PER KG PER DAY
GIVEN IN DIVIDED DOSES EVERY 4 TO 6 HOURS. IS THE
DOSAGE SAFE?
30
BODY WEIGHT (CONT.)
31
WEIGHT
(CONT.)
3. Determine mg BODY
allowed per
dose for dosing
every 6 hr
(4 doses in 24 hr)
15,900 mg ÷ 4 = 3,975 mg/dose
23,850 mg ÷ 4 = 5,962.5 mg/dose
4. Determine if dose is safe
4 g q6h = 4,000 mg q6h
Dose is within safe dose range
32
CALCULATING DOSAGES USING BODY
SURFACE AREA
• BSA USED FOR INFANTS, CHILDREN, BURN VICTIMS, ANTINEOPLASTIC
AGENTS, RENAL PATIENTS
• WEST NOMOGRAM IS BEST KNOWN BSA CHART
• COMPARE TO CHART INDICATING NORMS FOR CHILDREN OF SAME
HEIGHT AND WEIGHT
• BSA CAN ALSO BE DETERMINED BY A FORMULA CALCULATION USING
HEIGHT AND WEIGHT
33
Figure 25-1 West nomogram for estimation of body surface area. (From Kliegman RM, Stanton BF, St. Geme
JW, Schor NF, Behrman RE: Nelson textbook of pediatrics, ed 19, Philadelphia, 2011, Saunders.)
34
READING THE WEST NOMOGRAM
• INCREMENTS ARE INTENTIONALLY IRREGULAR
• NORMAL HEIGHT/WEIGHT (2ND FROM LEFT)
• BSA CAN BE DETERMINED BY WEIGHT ALONE
• EXAMPLES: NORMAL HEIGHT AND WEIGHT IN CHILDREN AND SMALL
ADULTS
• CHILD WEIGHING 70 LB HAS BSA OF 1.1 M2
• CHILD WEIGHING 10 LB HAS BSA OF 0.27 M2
• CHECK READINGS TWICE TO CONFIRM
35
70 lb child
Normal ht/wt
10 lb child
Normal ht/wt
36
(CONT.)
• FOR ABNORMAL HEIGHT/WEIGHT, USE FAR LEFT AND FAR RIGHT ON
NOMOGRAM
• USE RIGID STRAIGHT EDGE TO SPAN THE TWO
• MEASURE IN CENTIMETERS OR INCHES; MATCH TO KILOGRAMS AND
POUNDS, RESPECTIVELY
• BSA IS AT INTERSECTION OF SA COLUMN (CENTER)
37
50 lb / 36 in child
Abnormal ht/wt
38
(CONT.)
SAFETY ALERT
IN ORDER TO USE THE NORMAL COLUMN ON THE WEST
NOMOGRAM, YOU MUST BE FAMILIAR WITH THE NORMAL
HEIGHT AND WEIGHT STANDARDS FOR CHILDREN. CHECK
RELIABLE RESOURCES SUCH AS A PEDIATRIC GROWTH AND
DEVELOPMENT CHART. DO NOT GUESS ON THE NORMAL
HEIGHT AND WEIGHT.
39
CALCULATING BSA WITH FORMULA
• USED IN CRITICAL CARE DOSING AND CHEMOTHERAPY FOR CHILDREN
AND ADULTS
• SAFEST WAY—USE FORMULA AND CALCULATOR THAT PERFORMS
SQUARE ROOT FUNCTION
• BASED ON MEASUREMENTS OBTAINED
• USE SEPARATE FORMULAS FOR METRIC AND U.S. (HOUSEHOLD) UNITS—
CANNOT MIX THE TWO!
40
FORMULA FOR CALCULATING BSA FROM
KILOGRAMS AND CENTIMETERS
1.
MULTIPLY WEIGHT IN KILOGRAMS BY HEIGHT IN CENTIMETERS
2.
DIVIDE THE PRODUCT OBTAINED IN STEP 1 BY 3,600
3.
ENTER THE SQUARE ROOT SIGN INTO THE CALCULATOR
4.
ROUND THE FINAL BSA IN SQUARE METERS (M2) TO NEAREST
HUNDREDTH
41
KILOGRAMS AND CENTIMETERS (CONT.)
CALCULATE THE BSA FOR A CHILD WHO WEIGHS 23 KG AND IS 128
CM TALL.
42
POUNDS AND INCHES
1.
MULTIPLY WEIGHT IN POUNDS BY HEIGHT IN INCHES
2.
DIVIDE THE PRODUCT OBTAINED IN STEP 1 BY 3,131
3.
ENTER THE SQUARE ROOT SIGN INTO THE CALCULATOR
4.
ROUND THE FINAL BSA IN SQUARE METERS (M2) TO NEAREST
HUNDREDTH
43
•
FORMULA FOR CALCULATING BSA
FROM
POUNDS
AND
INCHES
(CONT.)
CALCULATE THE BSA FOR AN ADULT WHO WEIGHS 170 LB AND IS 67
IN TALL
44
CALCULATING BSA FOR CHILD DOSING
USING FORMULA
• A PEDIATRIC DOSAGE MAY BE CALCULATED FROM A RECOMMENDED
ADULT DOSAGE USING A FORMULA
• THE FORMULA USES THE AVERAGE ADULT DOSAGE, THE AVERAGE
ADULT BSA (1.7 SQUARE METERS), AND THE CHILD’S BSA
45
CALCULATING BSA FOR CHILD DOSING
USING FORMULA (CONT.)
46
TWO HOURS AFTER ADMINISTERING THE TYLENOL, TARA’S TEMPERATURE
HAS NORMALIZED. THE SURGICAL TEAM HAS BEEN TALKING TO TARA
AND HER MOTHER REGARDING THE PROCEDURE. THE
ANESTHESIOLOGIST ASKS YOU TO ADD TARA’S BSA TO THE CHART.
YOU RECALL HER HEIGHT: 35.5 INCHES AND HER WEIGHT: 32 LB 9 OZ.
WHAT IS HER BSA?
47
ANSWER:
TARA’S BSA IS 0.61 M².
48
IV THERAPY AND CHILDREN
• VERY SPECIFIC TO LEVEL OF DEVELOPMENT
• USE MICRODROP SETS AND/OR ELECTRONIC DEVICES
• SECONDARY INFUSIONS MAY BE DELIVERED AS IVPB OR IN BURETTE
(CALIBRATED CHAMBER)
• FLUSH TUBING (USUALLY WITH 15 ML OR SO) AFTER MEDICATION
DELIVERED, TO GET ALL OF THE MEDICATION
• CHECK PROTOCOL OF INSTITUTION
49
Figure 25-2 Volume-controlled device (burette). (From Potter PA, Perry AG, Stockert P, Hall A:
Fundamentals of nursing, ed 8, St Louis, 2013, Mosby.)
50
CALCULATING IV MEDICATIONS BY
BURETTE
• DROP FACTOR IS 60 GTT/ML
• FORMULA:
51
BURETTE (CONT.)
EXAMPLE: ANTIBIOTIC OF 100 MG IN 2 ML—DILUTE IN
20 ML OF D5W TO INFUSE OVER 30 MINUTES. A 15 ML FLUSH
FOLLOWS. ADMINISTRATION SET IS BURETTE.
STEP 1: READ LABEL TO DETERMINE VOLUME OF
AVAILABLE (100 MG:2 ML)
MEDICINE
STEP 2: ALLOW 18 ML OF D5W TO RUN INTO
ADD 2 ML CONTAINING THE
MEDICATION
BURETTE.
52
BURETTE (CONT.)
53
BURETTE (CONT.)
SAFETY ALERT!
IV INFUSIONS SHOULD BE MONITORED AS FREQUENTLY AS
EVERY HOUR. A SOLUTION TO FLUSH THE IV TUBING IS
ADMINISTERED AFTER THE MEDICATION.
54
YOU ARE TO ADMINISTER A PREOP ANTIBIOTIC TO TARA (14.8 KG). THE
ORDER READS:
VANCOMYCIN 148 MG IV OVER 2 HOURS Q6H
THE SAFE DOSE RANGE IS :
40 MG/KG/DAY IN 6-8 DIVIDED DOSAGES.
IS THE DOSE SAFE?
55
ANSWER: THE DOSE IS WITHIN SAFE RANGE.
YOU HAVE AVAILABLE 500 MG VIALS THAT MUST BE RECONSTITUTED
WITH 10 ML STERILE WATER FOR A CONCENTRATION OF 50 MG/ML.
THIS MUST BE FURTHER DILUTED WITH NS TO ≥ 5 MG/ML AND
ADMINISTERED OVER AT LEAST 60 MIN.
HOW MUCH OF THE RECONSTITUTED MEDICATION WILL YOU DRAW UP
AND HOW MUCH WILL YOU FURTHER DILUTE WITH?
56
ANSWER:
DRAW UP 3 ML (2.96 ROUNDED) AND FURTHER DILUTE WITH 30
ML NS.
YOU ARE TO ADMINISTER THE MEDICATION OVER 2 HOURS. YOUR
FACILITY POLICY REQUIRES YOU TO USE A BURETTE WITH MICRODRIP
TUBING AND A PUMP.
CALCULATE THE RATE IN GTT/MIN AND ML/HR.
57
ANSWER:
RUN THE INFUSION AT 15 GTT/MIN AND 15 ML/HR. YOU ALSO
REMEMBER TO FLUSH THE TUBING AT THE SAME RATE WITH AN
ADDITIONAL 15 ML NS.
TARA TOLERATES THE MEDICATION WELL AND SLEEPS THROUGH
THE NIGHT WITHOUT PAIN OR FEVER. SHE HAS BEEN NPO AFTER
MIDNIGHT AND SHE IS DRESSED IN A CLEAN GOWN BEFORE SHE
IS TAKEN TO SURGERY AT 0700. HER MOTHER THANKS YOU FOR
ALL YOUR HELP.
58
REMINDERS: PEDIATRIC ORAL AND
PARENTERAL MEDICATIONS
1. DOSAGES FOR CHILDREN ARE SMALLER THAN THOSE FOR
ADULTS
2. MOST MEDICATIONS FOR CHILDREN ARE LIQUID
3. ORAL ROUTE IS PREFERRED TO PARENTERAL
4. NOT MORE THAN 1 ML IM FOR SMALL CHILDREN AND
OLDER INFANTS; SMALL INFANTS SHOULD RECEIVE NOT
MORE THAN 0.5 ML IM
5. PARENTERAL DOSES ARE USUALLY GIVEN WITH
TUBERCULIN (TB) SYRINGES
6. CALCULATE DOSAGES TO ADMINISTER USING A RATIO
AND PROPORTION, FORMULA, OR DIMENSIONAL
ANALYSIS
59

Pediatric and Adult Weight Based Calculations

Transcription

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