What is the management of hypotension in infants?

Management of Hypotension in Infants

The management of hypotension in infants should follow a structured approach beginning with fluid resuscitation using isotonic crystalloids (10-20 mL/kg boluses), followed by vasopressor therapy with dopamine (starting at 2-5 mcg/kg/min) if fluid resuscitation fails to normalize blood pressure. 1, 2

Definition of Hypotension in Infants

Hypotension in infants is defined by age-specific criteria:

• Term neonates (0-28 days): Systolic BP <60 mmHg
• Infants (1-12 months): Systolic BP <70 mmHg 2

Initial Assessment

When evaluating an infant with suspected hypotension, assess for:

• Mental status changes (lethargy, irritability)
• Peripheral perfusion (capillary refill >3 seconds indicates poor perfusion)
• Urine output (<1 mL/kg/hr suggests inadequate perfusion)
• Distal pulses (weak or absent)
• Heart rate (bradycardia <90 bpm or tachycardia >160 bpm) 2, 1

Management Algorithm

Step 1: Fluid Resuscitation

• Administer isotonic crystalloid (normal saline) 10-20 mL/kg over 5-10 minutes
• May repeat up to 60 mL/kg if needed and no signs of fluid overload develop
• For preterm infants, use a more graded approach with smaller boluses (10 mL/kg) due to risk of intraventricular hemorrhage 2, 3
• If hemoglobin <12 g/dL, consider packed red blood cell transfusion 2

Step 2: Vasopressor Therapy (if fluid refractory)

• Start dopamine at 2-5 mcg/kg/min for infants likely to respond to modest increments of heart force and renal perfusion
• For more seriously ill infants, begin at 5 mcg/kg/min and increase gradually in 5-10 mcg/kg/min increments up to 20-50 mcg/kg/min as needed 4, 2
• Titrate to maintain adequate blood pressure, perfusion, and urine output

Step 3: Additional Therapies for Refractory Hypotension

• Add dobutamine if myocardial dysfunction is present 3
• Consider hydrocortisone if adrenal insufficiency is suspected (peak cortisol after ACTH <18 μg/dL) 2, 5
• For term newborns with PPHN, inhaled nitric oxide may be effective 2, 6
• For extremely refractory cases in term newborns, ECMO may be considered 2

Special Considerations for Preterm Infants

Preterm infants require special attention due to:

• Higher risk of intraventricular hemorrhage with rapid blood pressure fluctuations 2
• Potential persistence of patent ductus arteriosus 2
• Possible adrenal insufficiency contributing to vasopressor-resistant hypotension 3, 5

For preterm infants:

• Use a more cautious approach to fluid resuscitation (limit to 10-20 mL/kg) 3
• Consider early initiation of vasopressors rather than aggressive volume expansion 3
• A 5-day course of IV pentoxifylline (6 hours/day) may be beneficial in very low birth weight infants with septic shock 2

Monitoring Response to Treatment

Monitor:

• Blood pressure (continuous intra-arterial if possible)
• Heart rate and ECG
• Urine output (goal >1 mL/kg/hr)
• Mental status
• Peripheral perfusion (capillary refill <3 seconds)
• Oxygen saturation (goal >95%)
• Consider central venous oxygen saturation (goal >70%) 2

Pitfalls to Avoid

• Excessive fluid administration in preterm infants can worsen outcomes and increase risk of pulmonary edema, especially with patent ductus arteriosus 2, 3
• Failure to recognize adrenal insufficiency in vasopressor-resistant hypotension 5
• Treating hypotension based solely on blood pressure numbers without assessing overall perfusion status 7
• Delay in initiating vasopressor therapy when fluid resuscitation is ineffective 3
• Excessive dopamine doses (>50 mcg/kg/min) without monitoring for decreased urine output or tachyarrhythmias 4

By following this structured approach, clinicians can effectively manage hypotension in infants while minimizing risks of complications and optimizing outcomes.