Impediments to transition – The 5Hs

Jacqui McGregor

Impediments to transition – The 5Hs

Key Concepts

Risk factors contribution to problems with transitions
Impacts of hypothermia, hypoxia, hypoglycaemia, hypotension and hypercarbia on postnatal transition.

In this section and the next, we will consider conditions that may impede the transition to extra-uterine life, which link closely back to the notions of are they warm, sweet and pink!

Need for resuscitation

According to ANZCOR (2024) approximately only 10% of infants will require some assistance to transition and approximately only 0.1% will require extensive resuscitation.

The NeoResus program (2021) further outlines that clinicians need to ask themselves 3 important evaluating questions when assessing whether an infant transition

Is the infant term or preterm?
Is the infant breathing or crying?
Has the infant got good tone?

Predisposing risk factors that may impact transition

The below table highlights some of the predisposing factors that may impede transition to extrauterine life, these have been broken down into three (3) groups, maternal, intrapartum and fetal/newborn. These factors can impact on the gestation that infant is born at, whether the fetus incurs fetal distress in-utero and or hypoxia. Additionally physical anomalies such as cardiac defects may also impact this transition.

Maternal	Intrapartum	Fetal/newborn
Hypertensive disorders Substance abuse Chronic maternal illnesses Young 35 maternal age Fever and or Infection No or poor antenatal attendance Diabetes	Malposition (e.g. breech) Non reassuring fetal heart rate Prolonged labour greater than 24 hours Prolonged second stage Meconium-stained liquor Assisted birth (ventouse or forceps) Cord or placental complications (cord prolapse, abruption)	Congenital anomalies (e.g. heart defects, diaphragmatic hernia…) Pulmonary hypoplasia Infection/Sepsis Persistent pulmonary hypertension Prematurity Post weeks Deviation of fetal growth (SGR or LGA) Multiple parity Rhesus or other isoimmunisation

(NeoResus 2021)

The concept of the five (5) ‘H’s – which include hypothermia, hypoxia, hypoglycaemia, hypotension and hypercarbia – will be expanded on and how that these important elements can impact/impede transition as well as impact each other.

There are also predisposing factors such as maternal history, intrapartum history and or fetal or newborn complications that may cause haemodynamic instability that can impact the transition. Additional consideration will include patent ductus arteriosus (PDA) and duct dependent congenital heart conditions.

The 5 H’s

Consider how the following 5 H’s may impede the transition to extra-uterine life:

Hypothermia (are they warm?)

Infants are at risk for hypothermia due to their high surface area-to- body mass ratio, limited subcutaneous fat and limited ability to regulate temperature. Hypothermia can impact metabolic processes, and lead to increased oxygen and glucose consumption, which can exacerbate hypoxia and hypoglycaemia.

Hypoglycaemia (are they sweet?)

After birth, a newborn infant’s glucose supply from the placenta is cut off, and they rely on their own glycogen stores. Hypoglycaemia can occur if these stores are depleted, leading to decrease energy availability for critical functions, compounding the risk of hypotension and worsening overall condition and if left unmanaged can lead to neurological impairment. Low blood sugar levels may arise due to increased metabolic demands (e.g., from hypothermia or hypoxia) or due to fetal hyperinsulinemia.

Hypoxia (are they pink?)

Insufficient oxygen levels can occur if the infant has poor breathing and or ventilation. Hypoxia can impair glucose metabolism, when oxygen levels are low the body’s ability to efficiently metabolize glucose through aerobic processes is compromised, thus leading to hypoglycaemia. This can lead to further hypoxia, which in turn interferes with type II alveolar cells, which are responsible for producing surfactant production (decreases surfactant) which leads to vasoconstriction. Additionally in the premature infant surfactant is already in limited supply and hypoxia further impairs the synthesis and release of surfactant.

Hypotension (are they pink?)

Low blood pressure may arise from multiple factors, including inadequate blood volume, poor cardiac output, or stress response from hypoxia and hypoglycaemia. Hypotension can reduce perfusion to vital organs, leading to more severe hypoxia, metabolic disturbances and increase the risk of organ failure.

Hypercarbia (are they pink?)

Elevated carbon dioxide levels can occur when an infant has inadequate ventilation, often due to respiratory distress or poor adaptation. Hypercarbia can lead to respiratory acidosis, which may exacerbate hypoxia and contribute to the cycle of hypoglycaemia and hypotension.

In summary – The 5 H’s

The five (5) ‘H’ are interconnected and can exacerbate each other during a newborn infant’s transition. For example, hypothermia can increase oxygen and glucose consumption, which may lead to hypoxia and hypoglycaemia. In turn, hypoxia can impair the body’s ability to maintain blood pressure, potentially causing hypotension, as well as impair glucose metabolism, exacerbating risks of hypoglycaemia. Hypotension reduces blood flow to vital organs, further compromising the body’s ability to regulate glucose, leading to hypoglycaemia. Additionally, hypoxia and hypoventilation from inadequate breathing can result in hypercarbia (elevated carbon dioxide), creating a cycle that impairs respiratory function and oxygenation.