Please Quench My Thirst: A Review of Dehydration in the Pediatric Patient

Authors: John Riggins Jr MD, Adam Shore MD

Edited by: Wesley Chan MD and Robby Allen, MD

You are sitting in the pediatric emergency department on a beautiful but steamy day in July. You are feeling good about the summer. You have moved up in the ranks of residency. Your hours have gotten a little better. You wait for the next pediatric patient to be placed on the empty whiteboard so you can present your patient and show off your much improved clinical skills to your attending. 

A patient finally pops up on the board, and you sign up for them.

The chief complaint is “He’s not acting like himself”

You see a mom carry in her child to the examination room.

The patient is a 2-year-old fully vaccinated male with no significant past medical history who presents with fatigue, decreased PO intake, and “not acting like himself”. According to the mother, he has had episodes of vomiting and several episodes of watery stools yesterday that have since resolved. There is no history of fever or chills. There has been no recent travel, hospitalizations, or antibiotics use.

HR 140  BP 72/50  RR 25  T 98.7(R)  SpO2 100%  

General appearance: Tired-appearing, crying with no tears, sitting in mom’s arms
HEENT: Sunken eyes, dry mucous membranes, no erythema or exudate in pharynx
Cardiac: Tachycardia
Pulmonary: Tachypnea, no retractions or nasal flaring, no wheezes or rales
Abdomen: soft, non-tender, not distended
Skin: warm, decreased skin turgor, capillary refill > 3 seconds, no rashes 
Neuro: opens eyes to voice, moving all extremities equally 

You quickly diagnose severe dehydration in the patient after recalling some information from one of those morning reports that you heard last year. You go through the awesome notes that you took last year and review them. 

Dehydration Review

Dehydration: physiologic state of excess total body water loss. [1]

Degree of dehydration:

•         ● Mild: <5 % 
•         ● Moderate: 5-10% 
•         ● Severe: >10%

Why are children more prone to dehydration?

1.         1. Larger total body water content percentage compared to adults 
2.         2. Higher metabolic turnover rate
3.         3. Larger body surface area causing increased insensible losses
4.         4. Lack of independence to hydrate themselves
5.         5. Renal immaturity in Neonates [2]

Important History and Physical Exams Findings

Ask parents about:[3]

•         ● Tiredness
•         ● Crying with no tears
•         ● Decreased oral intake
  •                 ● When was the last PO intake?
  •                 ● What the child is taking by mouth (water, juice, pedialyte)?
•         ● Decreased urine output (<1 ml/kg/h). When was the last wet diaper or urine output?
•         ● History of vomiting
•         ● When was the last emesis? 
  •                 ● How frequently? 
•         ● History of diarrhea
  •                 ● Frequency and quantity of diarrhea?
  •                 ● Presence of blood or mucus? 

Important physical exam findings: [4] 

•         ● Tachycardia (usually first presenting sign)
•         ● Tachypnea 
•         ● Dry mucous membranes
•         ● Absent tears
•         ● Flattened fontanelle in infants 
•         ● Abnormal pulses
•         ● Sunken eyes 
•         ● Decreased skin elasticity 
•         ● Increased capillary refill ( > 2 seconds)

Using the clinical examination to diagnose the severity of dehydration in the pediatric patient is difficult. In Gorelick et al, a prospective cohort study looking at 10 different physical exam findings and their ability to predict dehydration, the authors concluded that any individual clinical sign by itself had both poor sensitivity and high specificity for dehydration defined as > 5% body weight loss in a pediatric patient. The combination of 2 or more of the clinical subset of symptoms of capillary refill > 2 seconds,  dry mucous membranes, absent tears, ill appearance had a higher likelihood ratio of predicting dehydration. [5]

The Clinical Dehydration scale (see Table) is a quick tool to help classify dehydration in children < 5 years old. [6,7]

Table: Clinical Dehydration Scale [7]

•         ● Fingerstick glucose 
•         ● BUN/creatinine (increased)
•         ● Bicarbonate (elevated at first and then decreased)
•         ● Urinalysis with specific gravity (elevated spec grav)

You are sitting at your desk deciding how you want to treat this patient. You know the patient needs fluids, but you begin to think through how you want to hydrate your patient. Should you order the IV fluid bolus or go and get that pedia-lyte in the cabinet for your patient?

Treatment of Dehydration:

Oral rehydration for mild and moderate dehydration who can tolerate PO intake [8,9]

•         ● Implementation of dilute apple juice and preferred liquids vs electrolyte maintenance solution alone reduces overall treatment failure [10]
•         ● Encourage age-appropriate small volumes by mouth every 2-3 minutes, and discourage rapid rehydration.

IV fluids for severe dehydration or mild/moderate dehydration who cannot tolerate PO intake:

•         ● 20 cc/kg  initial bolus of NS, up to 60 cc/kg in severe cases [11]

 Ondansetron 0.15 – 0.3mg/kg [12,13]

NS vs LR for fluid boluses?

•         ● In Kartha et al, a small double-blinded study  RCT w/ 69 patients showed that NS vs LR showed similar outcomes. The authors concluded that NS should be the fluid in pediatric patients with severe dehydration from diarrheal illness. [14]

You decide to go with the IV normal saline bolus and place the patient on maintenance fluids. But, how do you do that again? There was some rule that you know you learned before on your medical school pediatrics rotation but it is just not coming back to you. But then you recall that post you read the other day.

Maintenance fluids:

•         ● Use D5NS for maintenance.  Meta-analysis with 10 RCTs shows that maintenance fluids with isotonic fluids vs hypotonic fluids were better for prevention of hyponatremia [15,16]
•         ● 4-2-1 rule
  •                 ● First 10 kg:  4 mL/kg/hr
  •                 ● Second 10 kg:  2 mL/kg/hr
  •                 ● Every additional kg:  1 mL/kg/ hr
•         ● Our patient is 12 kg. Our maintenance fluids order would be D5NS given at a rate of 44 ml/hr = (4 x 10 kg) + (2 x 2 kg)

The patient looks a little better, but now the attending asks you that dreaded question: “So, what are you going to do with this patient: admit or discharge?” 

Disposition: 

If you are going to discharge your dehydrated patient, parents/caregivers need explicit discharge instructions with anticipatory guidelines to continue to replace fluid loss and maintenance hydration at home. 

Admit for:

•         ● Signs of severe dehydration
•         ● Inability to tolerate PO intake
•         ● Oliguria or anuria 
•         ● Metabolic abnormalities including hypoglycemia, hypokalemia, hyponatremia, hypernatremia, low bicarbonate
•         ● Hemodynamic abnormalities (hypotension, persistent tachycardia)
•         ● Significant ongoing loss (continued diarrhea)

Given the patient had signs of severe dehydration, initial hypotension and has not urinated for you in the emergency department, you admit the patient to the pediatrics floor for continued IV hydration and electrolyte repletion. Your patient does well on the floors thanks to your quick recognition of his condition and he is discharged two days later back home.

Pearls:

•         ● Consider dehydration in afebrile, tired-appearing child with tachycardia
•         ● Attempt PO hydration unless pt is severely dehydrated, actively vomiting even after anti-emetic therapy or has hemodynamic            instability
•         ● Closely monitor urine output
•         ● Re-assess fluid status often during resuscitation
•         ● Remember the “4-2-1 rule” for maintenance fluids
•         ● Remember 20 cc/kg initial NS bolus, up to 60 cc/kg in severe cases

References:

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Wesley Chan

EM/IM Resident Class of 2024

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