Airway and breathing

The infant’s airways differ from those of adults and older children in a number of ways that impact upon the response to infection, inflammation and foreign body inhalation. These differences also impact upon the emergency management of the infant’s airway and the equipment used to provide support and stabilization. The infant lungs are immature and have a relatively small surface area for gas exchange. The narrower airways of the infant are at greater risk of compromise even from relatively small amounts of inflammation, secretions and bronchospasm. This is because ‘resistance to airflow is inversely proportional to the fourth power of the airway radius (halving the radius increases the resistance 16-fold)’ (Advanced Life Support Group 2011). Being obligate nose breathers renders infants less than around 6 months old susceptible to airway obstruction from nasal secretions. The trachea of the infant is soft and therefore prone to compression from both flexion and extension of the neck. A collapsed or exhausted infant may need a folded towel or pillowcase placing under the shoulders to prevent flexion of the neck caused by the large occiput.

The soft cartilaginous ribs and pliable chest wall of the infant allows recession when the airway is partially obstructed. Recession indicates inefficiency of breathing as the infant’s effort to move the chest wall is not matched by the volume of air inspired. Sternal recession is more significant than subcostal and intercostal recession due to amount of effort required to move the larger sternum. The primary muscle of inspiration in the infant is the diaphragm and not the costals as in adults. Rib movement therefore contributes relatively little to chest expansion in infants. Consequently it is easier to determine the respiratory rate by direct observation of the abdomen and not the chest. Infants with respiratory distress are at risk of exhaustion having little respiratory reserve.

Circulation

The relative circulating volume is much higher in infants than in adults (80 mL/kg vs 50 mL/kg), however, the total volume is small in comparison. Therefore seemingly small amounts of blood loss can result in the rapid development of hypovolaemic shock. Cardiac output is the product of heart rate and stroke volume. Since the stroke volume in infants is relatively fixed, cardiac output can only be increased to meet metabolic demand by increasing the heart rate. Tachycardia is a compensatory mechanism to ensure oxygen and metabolite delivery to the tissues, such as in respiratory distress, sepsis or dehydration. The emergency nurse should be mindful that tachycardia can also be induced by excitement or anxiety and the aim should be to minimize distress.

Significant tachycardia is not sustainable and will eventually lead to decompensation. During the decompensatory phase of shock the heart rate will begin to fall and a normal heart rate in a seriously unwell infant may be misinterpreted as an improvement in condition. Bradycardia is a pre-terminal sign. Close attention to heart rate and rhythm, skin colour and temperature, capillary refill time (CRT) and mental status are key to early recognition of compensated shock. A CRT of >2 seconds indicates poor perfusion, although this may be influenced by a number of factors, particularly cold. Capillary refill should be recorded serially to monitor the response of any measures undertaken to improve circulatory status and is recognized as a better indicator of tissue perfusion than systolic blood pressure (Salter & Maconochie 2005).

Disability

By far the most useful source of information regarding change to the infant’s normal abilities, posture and tone are the parents, and their concerns should be held in high regard. Modified paediatric Glasgow coma scores (GCS) are available and very useful, however, the AVPU score provides a quick and simple tool to assess whether the infant is alert, responsive to voice, responsive to pain, or is unresponsive. A child who only responds to pain or who is unresponsive has an equivalent GCS of 8 or less. Babies who are floppy, drowsy or difficult to rouse, irritable on handling and/or have a high-pitched cry should be treated with a high index of suspicion for a neurological problem and have a full set of neurological observations measured and recorded. It is important to obtain an accurate history to illicit details of potential trauma or poisoning and any relevant past medical history. Infants, especially neonates, are particularly sensitive to hypoglycaemia and the emergency nurse should always remember ‘DEFG’ – ‘don’t ever forget glucose’. Heel-prick testing is preferred and training is required to select the appropriate sites, which include the lateral and medial edges of the heel and not the centre.

Pain assessment

Pain is often under-recognized and under-treated in the ED (Todd et al. 2002). This can be particularly difficult in infants. The emergency nurse should be trained in the use of pain assessment tools specific to infants and treatment given according to the determined severity. One such tool is the FLACC tool that scores facial expression, leg movement, activity, consolability and crying on a scale of 0–2, the combined total providing a score out of ten (Table 16.4 and Box 16.3). The crying/screaming infant should be presumed to be in pain when none of the usual parental comforting methods such as feeding and rocking are effective. Specific signs such as drawing-up the legs indicating abdominal pain or reluctance to move a particular limb should guide the assessment. Oral sucrose solution and non-nutritive sucking can be used in young infants to provide analgesia during painful procedures such as intravenous cannulation. Consideration of opioid analgesics should be discussed with experienced paediatric-trained staff when simple oral analgesia such as paracetamol and ibuprofen are insufficient.

Respiratory assessment

The infants’ pattern of breathing must be assessed in terms of rate, rhythm and effort. The number of breaths should be counted for 60 seconds (Royal College of Nursing 2007); this is best achieved by observing abdominal movement. Quick count methods (30- or 15-second counts) or using electronic monitors have been shown to be inaccurate as often as 62 % of the time (Lovett et al. 2005). Worryingly, bradypnoea is almost always missed even though it is indicative of hypoxia and is pre-terminal (Advanced Life Support Group 2011). Tachypnoea may be difficult to count, as often the smaller ‘panting’ breaths are missed (Aylott 2006a). In these circumstances auscultation is necessary. Other clinical signs of respiratory distress include nasal flaring, use of accessory muscles, head-bobbing, intercostal/subcostal/sternal/supraclavicular recession and tracheal tug. See-sawing, which is the paradoxical movement of the chest and abdomen (i.e., the chest falls and abdomen rises during inspiration), represents extremely inefficient breathing and results from significant airway obstruction. Added breath sounds such as grunting, stridor and wheezing may be heard. Grunting is often a sign of significant respiratory or metabolic disease. This is caused by the infant breathing out against a partially closed glottis in order to generate positive end expiratory pressure (PEEP) to prevent alveolar collapse. Wheezing is a high-pitched, musical, expiratory sound indicative of lower airway pathology such as in bronchiolitis and other viral infections. It is caused by turbulent airflow through very narrow airways (Aylott 2006b). Wheezing may also be heard in cardiac failure. Stridor is a harsh, low-pitched, usually inspiratory noise indicative of upper airway obstruction, for example in croup or foreign body obstruction.

Cardiovascular assessment

The heart rate in infants should be measured for a full minute by auscultation of the apex beat and electronic measurements should be verified manually (Royal College of Nursing 2007). The apex beat can be heard over the 5th intercostal space in the left, mid-clavicular line. This should be consistent with the brachial pulse, which is palpated on the medial aspect of the upper arm. The carotid and radial pulses are not used routinely in infants as they are difficult to locate. The skin colour and temperature should be consistent over the trunk and limbs; however, when assessing the patient consider the ambient temperature. Decreased skin perfusion can be an early sign of shock. Clinical signs of poor perfusion include peripherally cool skin, pallor, mottling and peripheral cyanosis. CRT is very useful in assessing perfusion. The sternum or forehead are preferred sites (Maconochie 1998) as ambient temperatures can affect peripheral sites. Sufficient pressure to cause the skin to blanch should be applied for five seconds and the length of time for normal colour to return recorded (Castle 2002). Normal capillary refill time is <2 seconds in post-neonatal infants and <3 seconds in neonates. When recording blood pressure, the size of cuff should be at least two-thirds of the length of the upper arm (or lower leg) and the inflatable portion should cover the entire circumference of the limb. This is essential to obtain an accurate reading. It is usually best to leave this measurement to last as it is the least useful data in most cases and tends to be distressing. The first automated blood pressure measurement should be disregarded (Royal College of Nursing 2007). Enquiring about fluid input and output, i.e., drinking well, vomiting, diarrhoea, frequency of wet nappies and observing for moist mucous membranes are all aspects of the cardiovascular assessment.