Airway

The ability to speak or cry without stridor indicates a patent airway. The presence of adequate breathing as assessed by looking at chest wall movement, listening and feeling for exhaled air also indicates an adequate airway.

Generally, shock affects the airway by reducing conscious level. In acute allergic reaction, airway obstruction (by swelling in the upper airway) and shock due to changes in vascular tone, can both arise as part of the same process.

Breathing

The effort of breathing, efficacy of breathing and effects of inadequate respiration should be examined. Oxygen saturation and respiratory rate should be monitored.

Circulation

This is the crux of shock assessment since homeostatic mechanisms function particularly well in children and compensation for inadequate circulatory function is good. Consequently, in a child it can be difficult to detect circulatory failure until a late stage, hence one needs to be vigilant in detecting the earlier features of compensating shock.

Circulatory assessment should look at both circulatory status and also at the effects of inadequate circulation on other organ systems.

Heart rate and blood pressure are the classical measures of circulatory status but changes in skin perfusion (as shown by capillary refill and by skin pallor or temperature) can be more useful in detecting the early signs of compensated shock.

Heart rate

Tachycardia (relative to age norm) is a key sign of shock (see Chapter 1.1). This tachycardia is a homeostatic response to maintaining cardiac output. Bradycardia may occur pre-terminally in the child with overwhelming shock, and untreated will progress to asystole. The peripheral pulses may be weak, thready or absent.

Blood pressure

While it is true that a child with hypotension is shocked it is not true to say that a child that is normotensive is not shocked. This is because maintenance of blood pressure is the key end point of the homeostatic response, and decompensation (and thereby hypotension) occurs late and may be precipitous. The accurate measurement of blood pressure in a distressed child can be a challenge in itself and a judgement as to whether a particular blood pressure is normal or abnormal in a particular age group in any particular circumstances is also challenging. Many widely quoted normal ranges by age are broad – furthermore many of these were derived in the resting outpatient child rather than in the seriously ill or injured child.

Capillary refill

The capillary refill time is measured by applying pressure to the nail bed or other area with visible circulation for some five seconds and then measuring the length of time it takes for the blanching to disappear. Central capillary refill such as over the sternum is more reliable than the peripheries which can be influenced by vasoconstriction due to the ambient temperature effects. A capillary refill time of less than two seconds is normal. A capillary refill time of greater than four seconds is definitely abnormal. Capillary refill between two and four seconds should prompt further consideration of the presence of shock.

Changes in peripheral circulation (which are brought about by an increase in catecholamines) may also show as an increased core to periphery temperature difference (more than 2°C is a sign of poor perfusion) or as a noticeable centripetal temperature gradient. Reduced skin perfusion may result in a mottled, cyanosed, pale appearance and coolness on palpation. Some infants have physiological mottling (cutis marmoratum) in the first months of life due to ‘immaturity’ of the autonomic control of skin vessels, which commonly occurs with exposure. One must clarify with parents whether this mottled appearance is ‘more than usual’ in their child, as infants with cutis marmoratum will become more mottled if they have an accompanying illness causing shock.

Effects of circulatory inadequacy

Agitation and altered conscious level (that is response to voice or less) are important signs of circulatory inadequacy and the resultant cerebral hypoperfusion. In infants, the manifestations may be more subtle and increased ‘irritability’ or ‘floppiness’ or failure to recognise and make eye contact with parents may be the only obvious manifestation.

Increasing respiratory rate is an early sign of inadequate circulation. Latterly, as acidosis ensues, deep sighing respirations occur due to ‘air hunger’.

Urine output will decrease with inadequate circulation. If a child has a urine collection device in place then a flow of some 2 mg kg^–1 hr^–1 in the child under one, and 1 mg kg^–1 hr^–1 in older children indicates adequate renal perfusion. If there is no urinary collection device then this can be difficult to assess, but the weight of wet nappies may be helpful.

Neurological status

As mentioned above, initially agitation and then subsequently depression in conscious level are associated with progressing shock. As in any other case of decreased conscious level a glucose stick test should be performed to exclude hypoglycaemia.

Circulation

Once airway and breathing have been managed, the next priority is to gain intravascular access. This should be obtained rapidly. An initial assessment to see whether there is a vein available to allow the placement of a short, relatively large, peripheral venous catheter is made. If it is likely that such a catheter can be placed, then up to two attempts can be allowed. If these attempts are unsuccessful (or if there is no possibility of placing a venous catheter) then intraosseous access should be gained. In most cases this is done over the medial aspect of the tibia just distal to the knee (see Chapter 23.1).

If neither peripheral venous access nor intraosseous access is possible or desirable, then a Seldinger (guide wire) approach to the femoral vein is probably the next route of choice.

As soon as intravascular access is obtained then blood should be drawn to be tested for haemoglobin, white cell count and platelets together with urea, electrolytes, acid base and lactate level. A blood culture should be taken and a glucose stick test performed to exclude hypoglycaemia.

An initial bolus of 20 mL kg^–1 of fluid should be given. In most cases the initial fluid will be crystalloid but occasionally universal donor blood may be indicated. There is some controversy as to whether colloid should be administered in cases of sepsis, with proponents arguing that maintenance of oncotic pressure is important in this situation.

If a glucose stick test reveals significant hypoglycaemia then glucose should be administered (5 mL kg^–1 of 10% dextrose). In such a case, hypoglycaemia may be the primary problem but it may also co-exist with other causes of serious illness and resuscitation must therefore be continued if immediate recovery does not ensue with correction of the blood glucose.

If a tachydysrhythmia is identified as a cause of established shock then cardioversion is indicated. This should be undertaken without delay. If the child is alert or otherwise responsive then sedation is usually indicated. If the tachydysrhythmia is supraventricular tachycardia then it may be quicker to give a single bolus of adenosine while preparing for cardioversion (see Chapter 5.9).

If no other cause of shock can be found then it is reasonable to give a broad-spectrum antibiotic as part of the initial treatment, as sepsis is the most common precipitant of shock in children. A third generation cephalosporin should therefore be given as soon as the blood culture has been taken, to children beyond the neonatal age, where amoxicillin and gentamicin are used as empirical sepsis cover.

Hypovolaemia

This diagnosis is usually made because of the presence of trauma, fluid loss from vomiting or diarrhoea or a surgical abdomen.

The further treatment depends on the response to initial fluid bolus. If there are still signs of shock then a second 20 mL kg^–1 bolus should be given. At this stage a surgical opinion should be sought if an underlying surgical cause is suspected.

It would be most unusual for a child with gastroenteritis to require more than two boluses of crystalloid and, if this is the case, then an alternative diagnosis (such as an underlying intra-abdominal surgical problem or adrenal insufficiency) should be considered.

If the child shows no further signs of shock after two fluid boluses and the underlying diagnosis is gastroenteritis, then it will still be necessary to correct any underlying dehydration and this should be done in the normal manner (see Chapter 7.12).

Septic shock

Septic shock arises because of a complex combination of hypovolaemia (relative and absolute), cardiogenic shock (due to myocardial depression) and distributive shock. The underlying cause is, of course, the infection and this should be treated as a matter of urgency. As previously stated, any shocked child in whom there is not an obvious diagnosis should receive broad-spectrum antibiotics as part of the initial management. If a specific diagnosis of septicaemic shock is made and antibiotics have not been given then these broad-spectrum antibiotics (third generation cephalosporins) should be given immediately. Consideration should also be given for a specific prescription of anti-staphylococcal antibiotics such as flucloxacillin and vancomycin if there is evidence of cellulitis or a foreign body, or if the clinical picture is of toxic shock syndrome (high fever, confusion, scarlatina-form rash with desquamation and subcutaneous oedema).

In all cases a further bolus of 20 mL kg^–1 of fluid should be given if there is not rapid restoration of normal circulation following the first bolus. A further fluid bolus should be administered (by IV push) if there is not a good response to the second. It is at this stage that urgent consideration to rapid sequence induction and elective intubation should be given. Many children will develop a degree of pulmonary oedema after the third fluid bolus and oxygenation can only be maintained by positive pressure ventilation (often with the addition of positive end-expiratory pressure).

Cardiogenic shock is also a feature of sepsis and this will require specific treatment. Dobutamine at a rate of 10 mcg kg^–1 min^–1 should be commenced and adjusted according to the response. Adrenaline (epinephrine) should be considered if there is no response to dobutamine.

Features of raised intracranial pressure due to meningitis can occur during treatment. This is usually presaged by a decrease in conscious level together with abnormal posturing or focal neurology. Early appropriate treatment should be commenced and this will include consideration of diuresis, intubation and ventilation and appropriate positioning of the patient. In this situation, a lumbar puncture is contraindicated.

Duct-dependent congenital heart disease

There are a number of congenital heart defects in which the presence of a patent ductus arteriosus is essential to the maintenance of pulmonary or systemic circulation. These conditions include pulmonary atresia, hypoplastic left heart syndrome, coarctation and critical aortic stenosis. The ductus usually closes functionally within 24 hours of birth – but may remain patent in the presence of cardiac abnormality.

Babies with critical pulmonary lesions will present within a few days of birth with tachypnoea and apparent breathlessness together with cyanosis, while those with systemic blood flow reduction will present with failure to feed, apparent breathlessness and collapse with poor peripheral circulation. The immediate impression, particularly in the latter group, may well be of severe sepsis and empirical antibiotics should be given until sepsis is excluded.

On examination, the babies are in heart failure (usually without a characteristic heart murmur), often with an enlarged liver and a gallop rhythm.

Immediate treatment is to maintain or increase ductus size with an infusion of alprostodil (0.05 mcg kg^–1 min^–1). Immediate transfer to a cardiological centre is indicated. It will usually be necessary to intubate and ventilate these children during transfer.

Heart failure

In babies, heart failure is usually due to structural heart disease, while in older children myocarditis and cardiomyopathy are the commonest underlying diagnoses.

Babies present with breathlessness, feeding problems and failure to thrive and restlessness. In older children more general complaints such as fatigue, anorexia, exercise intolerance and cough are common.

There are signs of increased effort of breathing with increased respiratory rate, recession and positioning. There is an increased heart rate with cool, pale peripheries together with hepatomegaly. On auscultation there may be a gallop rhythm and basal crepitations.

Oxygen should be given in all cases and broad-spectrum antibiotics administered if there is any suspicion of sepsis. As discussed earlier, alprostadil should be given if the lesion is potentially duct dependent. In other cases diuretics (furosemide 1–2 mg kg^–1 day^–1 in one to three divided doses initially) should be given urgently. A dobutamine infusion may be indicated to support the failing heart while urgent cardiological advice is sought.

Acute severe allergic reaction (anaphylaxis)

A diagnosis of acute allergic reaction will usually be made because of a history of a previous similar reaction, or because of the presence of typical early symptoms such as itching, facial swelling, urticarial rash, abdominal pain or wheeze.

The initial approach to shock is appropriate administration of fluid boluses. Anaphylactic circulatory shock will usually respond to adrenaline (epinephrine). The recommended dose is 10 mcg kg^–1 given intramuscularly. Judicious use of 1:100 000 adrenaline solution given intravenously in small incremental boluses can also be effective. Over enthusiastic administration of adrenaline in the face of mild allergic reaction or, indeed, in the face of an anxiety attack has resulted in severe dysrhythmias. Caution should therefore be exercised (see Chapter 22.5).

If circulatory shock is resistant to the initial bolus of adrenaline then a further intravenous bolus of 20 mL kg^–1 of fluid should be given. At this stage, if the diagnosis is clear, then an infusion of adrenaline at 0.1–5 mcg kg^–1 min^–1 should be commenced.

Neurogenic shock

A child with a spinal injury above T6 will have impaired sympathetic tone below this level once the initial catecholamine release that occurs at the time of injury has ceased to have an effect. The systemic vascular resistance will fall and the reflex tachycardia usually seen as a response to hypovolaemia will not occur. The overall outcome is generalised vasodilatation, bradycardia and loss of temperature control. Systolic blood pressure will fall below 90 mmHg but the skin will appear paradoxically warm and pink.

Initial management is with fluids and a single bolus of 20 mL kg^–1 will usually achieve an acceptable blood pressure. Atropine (20 mcg kg^–1) can be given if heart rate falls below 50. Very careful handling is necessary as these children may suffer from postural hypotension if tipped or lifted suddenly. In the early stages fluid management is very important and this may require the insertion of arterial and pulmonary lines. Urinary catheterisation will be necessary as bladder control will be lost.

Concomitant absolute hypovolaemia due to trauma must always be considered, as neurogenic shock is invariably caused by trauma in children. Bleeding sources should be actively sought and managed in all children in whom hypotension persists, with early surgical consultation.