Math: Basic Tutorials : Intake & Output

Intake & Output

Order of Operations Video transcript - RTF

Monitoring intake and output (I&O) is a critical aspect of client care that helps evaluate fluid balance in the body. Fluid balance refers to the relationship between the fluids a client takes in—such as through oral intake, IV fluids, or tube feedings—and the fluids they lose, including urine, emesis, feces, sweat, or surgical drains. Tracking I&O accurately not only sharpens your math skills, but also connects directly to real-life clinical decisions. For example, identifying a positive or negative fluid balance can signal potential issues like dehydration, fluid overload, or kidney dysfunction. Understanding the math behind these values helps you recognize what’s happening physiologically and take timely action to support your client’s health and safety.

This section covers how to interpret I&O data to assess fluid balance, recognize potential complications such as dehydration or overhydration, and make informed decisions about client care. Practical examples will help reinforce how to document and calculate these values effectively.

fluid balance = total intake − total output

Step 1: Identify inputs

Oral: any liquids
IV (e.g., normal saline, D5W, lactated ringers, etc.)
IV med
Total parenteral nutrition (TPN)
Peripheral parenteral nutrition (PPN)

Step 2: Identify outputs

Urine: void, urine, foley catheter
Emesis (vomit)
Stool
Drainage (e.g., wound, surgical, fistula, etc.)
Nasogastric (NG) tubes

Step 3: Put it all together

Positive (+): When intake is greater than output, the result will be positive.
Equal (=): When intake is equal to output, the result is equal.
Negative (−): When intake is less than output, the result will be negative.

Positive Fluid Balance

This occurs when fluid intake exceeds output, which may lead to fluid overload or edema if not monitored closely.

Possible Reasons:
IV fluid overload (e.g., aggressive fluid resuscitation). Heart failure (inability of the heart to pump effectively, leading to fluid retention). Kidney dysfunction (reduced ability to excrete fluids). SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion) – promotes water retention. Low urine output (e.g., oliguria or anuria).
Clinical Signs:
Edema. Pulmonary congestion. Hypertension. Weight gain.

Equal (Neutral) Fluid Balance

This occurs when fluid intake and output are approximately equal, indicating stable fluid status.

Possible Reasons:
Appropriate fluid management. Healthy renal, cardiac, and endocrine function. Normal insensible losses accounted for in fluid orders. ** Insensible fluid losses** are fluid losses that occur without the person's awareness and are not easily measured.
Sources of Insensible Losses:
Respiration (water vapor lost during breathing). Skin evaporation (not including sweating). Stool (minimal loss unless diarrhea is present).
Average Insensible Losses:
Approximately 500–600 mL/day in adults. May be higher in febrile states, increased respiratory rates, or in warm environments.
Clinical Consideration:
While not recorded on fluid balance charts, insensible losses must be considered when assessing fluid needs.

Negative Fluid Balance

This occurs when fluid output exceeds intake, leading to potential hypovolemia or dehydration.

Possible Reasons:
Diuretics (excessive urination). Vomiting or diarrhea. Excessive sweating. Fever (increased metabolic demand and evaporative loss). Bleeding. Uncontrolled diabetes (osmotic diuresis).
Clinical Signs:
Hypotension. Tachycardia. Dry mucous membranes. Decreased skin turgor. Dizziness or orthostatic hypotension.

Calculating Fluid Requirements involves determining how much fluid a client needs based on their current condition, ongoing losses (like vomiting or drainage), and prescribed treatments (such as IV fluids). This process is essential to maintain proper hydration, electrolyte balance, and overall physiological stability. By accurately calculating intake needs, nurses support safe, effective care and respond to changes in a client’s condition. To begin, it’s important to understand how to calculate the total volume of IV fluids a client will receive over a given period.

Calculating Total IV Fluids

Determine the IV Rate:Identify the rate at which IV fluids are being administered, usually given in mL/hour.
Identify the Time Period:Note the total number of hours the IV infusion runs.
Multiply to Find Total Volume:Multiply the IV rate by the number of hours to calculate the total volume of fluid delivered.
Include Additional Fluids:If other fluids (e.g., piggyback medications, flushes, secondary infusions, NG replacements, etc.) are administered, add their volumes to the total.
Add All Volumes Together:Sum the primary infusion and any additional fluids to get the total IV fluid intake.

Click on the titles below to view each example. Some examples will focus on calculating fluid balance, while others will guide you through determining total IV fluid volumes.

Example 1

During a 12-hour shift from 0600H to 1800H, the client had 40 mL/h of IV infused starting from 0600H. At 1200H, the IV rate was increased to 55 mL/h, and IV infusions were stopped at 1500H. TPN was started at 1500H at 25 mL/h. The client drank 120 mL of water at 0700H along with 3 cookies weighing 15 g. At 0900H, the client had 200 mL of liquid feces. At 1230H, the client consumed 20 mL of ice chips and 5 mL of ice pop. At 1400H, the client ate a sandwich and had 100 mL of juice, 20 mL of ice cream, and one cup (240 mL) of water. At 1600H, the client voided 150 mL of urine and had 40 mL of emesis. Finally, at the end of the shift, 80 mL was emptied from the client’s surgical drain.

Fill in the I&O table and find the fluid balance.

Step 1: Highlight/ Identify the inputs, volume, time

During a 12-hour shift from 0600H to 1800H, the client had 40 mL/h of IV infused starting from 0600H. At 1200H, the IV rate was increased to 55 mL/h, and IV infusions were stopped at 1500H. TPN was started at 1500H at 25 mL/h. The client drank 120 mL of water at 0700H along with 3 cookies weighing 15 g. At 0900H, the client had 200 mL of liquid feces. The client had 20 mL of ice chips and 5 mL of ice pop at 1230H. The client ate at 1400H and had a sandwich, 100 mL of juice, 20 mL of ice cream and one cup of water. At 1600H the client went to the bathroom to void 150 mL of urine and 40 mL of emesis. Finally, at the end of the shift, 80 mL was emptied from the client's surgical drain.

IV
- 40 mL/h from 0600H to 1200H
- 55 mL/h from 1200H to 1500H
Oral (note: solid foods are not accounted for)
- 120 mL of water at 0700H
- 10 mL of ice chips (half volume) at 1230H
- 5 mL of ice pop at 1230H
- 100 mL of juice at 1400H
- 20 mL of ice cream at 1400H
- 240 mL (converted one cup) of water at 1400H
TPN
- 25 mL/h from 1500H to 1800H

Step 2: Highlight/identify the outputs, volume, time

During a 12-hour shift from 0600H to 1800H, the client had 40 mL/h of IV infused starting from 0600H. At 1200H, the IV rate was increased to 55 mL/h, and IV infusions were stopped at 1500H. TPN was started at 1500H at 25 mL/h. The client drank 120 mL of water at 0700H along with 3 cookies weighing 15 g. At 0900H, the client had 200 mL of liquid feces. The client had 20 mL of ice chips and 5 mL of ice pop at 1230H. The client ate at 1400H and had a sandwich, 100 mL of juice, 20 mL of ice cream and one cup of water. At 1600H the client went to the bathroom to void 150 mL of urine and 40 mL of emesis. Finally, at the end of the shift, 80 mL was emptied from the client's surgical drain.

Stool
- 200 mL at 0900H
Urine
- 150 mL at 1600H
Emesis
- 40 mL at 1600H
Drain
- 80 mL at 1800H

Intake	0600H-0700H	0700H-0800H	0800H-0900H	0900H-1000H	1000H-1100H	1100H-1200H	1200H-1300H	1300H-1400H	1400H-1500H	1500H-1600H	1600H-1700H	1700H-1800H	Total
IV	40	40	40	40	40	40	55	55	55				405
Oral		120					15		360				495
TPN										25	25	25	75
Shift Total	40	160	40	40	40	40	70	55	415	25	25	25	975

Output	0900H-1000H	1600H-1700H	1700H-1800H	Total
Stool	200			200
Urine		150		150
Emesis		40		40
Drain			80	80
Shift Total	200	190	80	470

Solution:

The fluid balance would be total intake (975 mL) minus total output (470 mL)

975 − 470 = +505 (positive since total intake > total output)

Example 2

The day nurse uses the following information to complete the day record (0700H - 1500H)

The client eats an apple, 45 mL of milk and 13 g of cereal for breakfast. He has 20 mL/h of IV infusing from 0900H to 1400H. The IV is held for 2 hours while 40 mL of 20 mEq D5W is administered from 1200H to 1500H. During lunch, he eats 3 oz of ice chips, a salad and 2 slices of bread. 400 mL was emptied from his foley catheter near the end of his shift.

The evening nurse uses the following information to complete the evening record (1500H - 2300H)

Throughout the whole shift, 10 mL/h of IV was administered. Before dinner, the client was feeling unwell and vomited 120 mL of emesis. He then ate a sandwich and drank 300 mL of hot tea. Before heading to bed, 210 mL was emptied from his foley catheter and he had 5 tablespoons of pudding.

Intake
Shift	Oral	IV	Other	Total
Day	45 + (1.5 × 30) = 90 mL	20 × 5 = 100 mL	40 mL	275 mL
Evening	300 + (5 × 15) = 375 mL	10 × 8 = 80 mL		455 mL
Total	510 mL	180 mL	40 mL	730 mL

Output
Shift	Urine	Emesis	Other	Total
Day	400 mL			400 mL
Evening	210 mL	120 mL		310 mL
Total	610 mL	120 mL		730 mL

Solution:

The fluid balance is equal since total intake = total output

Example 3

A client with severe vomiting has a nasogastric tube in place, connected to wall suction at -20 cm. The primary line IV is infusing a D5NS (5% dextrose in normal saline) at 125 mL/hr. You are starting your 8-hour day shift, and the night nurse reports that the NG tube drained 480 mL during the night shift.

The MD order reads: "Replace NG losses 1:1 with NS with 20 meq of KCL qshift."

Question: What is the total amount of IV fluid this client will receive during your day shift?

Given:

Primary IV line: D5NS at 125 mL/hr
Duration of shift: 8 hours
NG output (night shift): 480 mL
Order: Replace NG losses 1:1 with NS + 20 mEq KCl per shift (based on previous shift's NG losses)

Step 1: Calculate Primary IV Fluids

Primary IV rate = 125 mL/hr

Time = 8 hours

125 mL/hr × 8 hr = 1,000 mL

Primary IV Total:

1,000 mL

Step 2: Calculate NG Replacement Fluid

Per order, replace the previous shift's NG output 1:1 with with NS + 20 mEq KCl	NG output = 480 mL
NG Replacement Total:	480 mL of NS + 20 mEq KCl

Step 3: Total IV Fluids for Day Shift

Primary IV: 1,000 mL NG Replacement: 480 mL	1,000 mL + 480 mL = 1,480 mL
Solution:	The client will receive a total of 1,480 mL of IV fluid during the 8-hour day shift.

Example 4

A client with persistent nausea and vomiting has a nasogastric tube in place, connected to wall suction at -20 cm. The primary IV is infusing 2/3 D5 and 1/3 NS at 95 mL/hr. You are starting your 12-hour day shift, and the night nurse reports that the NG tube drained 720 mL during the night shift.

The physician's order reads: “Replace NG losses 1:1 with NS + 20 mEq KCl once per shift.”

Question: What is the total amount of IV fluid the client will receive during your 12-hour day shift?

Step 1: Calculate Primary IV Fluids

Rate = 95 mL/hr Duration = 12 hours	95 × 12 = 1,140 mL
Primary IV total:	1,140 mL

Step 3: Calculate NG Replacement Fluid

Per order, replace the previous shift's NG output 1:1 with with NS + 20 mEq KCl.	NG output = 720 mL
NG Replacement Total:	720 mL of NS + 20 mEq KCl.

Step 3: Total IV Fluids for Day Shift

Primary IV: 1,140 mL NG Replacement: 720 mL	1,140 + 720 = 1,860 mL
Solution:	The client will receive a total of 1,860 mL of IV fluid over the 12-hour day shift.

Practice

Client Assessment (I&O) Practice Questions

Last Updated: Jun 5, 2025 4:16 PM
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Math: Basic Tutorials

Math: Basic Tutorials : Intake & Output

Intake & Output

fluid balance = total intake − total output

Step 1: Identify inputs

Step 2: Identify outputs

Step 3: Put it all together

Positive Fluid Balance

Equal (Neutral) Fluid Balance

Negative Fluid Balance

Calculating Total IV Fluids

Example 1

Step 1: Highlight/ Identify the inputs, volume, time

Step 2: Highlight/identify the outputs, volume, time

Example 2

The day nurse uses the following information to complete the day record (0700H - 1500H)

The evening nurse uses the following information to complete the evening record (1500H - 2300H)

Example 3

Given:

Step 1: Calculate Primary IV Fluids

Step 2: Calculate NG Replacement Fluid

Step 3: Total IV Fluids for Day Shift

Example 4

Step 1: Calculate Primary IV Fluids

Step 3: Calculate NG Replacement Fluid

Step 3: Total IV Fluids for Day Shift

Practice