Emergency Treatment in Pediatric

Shock in Pediatric

Shock is most simply conceptualised as failure of the circulation to provide adequate delivery of oxygen and essential nutrients to the tissues to ensure normal cell respiration. The process leading to this state may be single or multifactorial. In the management of sick and injured children, the emphasis lies in swift recognition of shock followed by rapid assessment of the nature of the circulatory failure. The latter is essential because avoidance of significant morbidity and mortality relies on the clinician’s ability to determine the origin(s) of the shock accurately and initiate appropriate and specific management.

At a cellular level inadequate oxygen delivery leads to lactic acid formation and the development of metabolic acidosis. Up to a point the body compensates for this by redistributing blood flow away from non-essential tissues (e.g. mesenteric circulation, skin) to the vital organs (e.g. brain and heart). This state of compensated shock is completed by increased extraction of oxygen from the blood by these essential organs to maintain oxygen delivery. Uncompensated shock develops when despite these mechanisms the pathological insult makes it impossible for the body’s vital organs to overcome the inadequacy of oxygen delivery. Untreated, uncompensated shock will inevitably lead to a spiralling deterioration. An inflammatory cascade ensues at the endothelium causing cellular tissue damage. If prolonged, this damage becomes irreversible and indeed restoration of adequate circulation at this stage may lead to reperfusion injury, itself exacerbating the damage. Multi-organ failure will follow, which in many cases will be unrecoverable. However, compensated and early, uncompensated shock are treatable and so this chapter focuses on the clinician’s recognition, assessment and initial management of shock in the Pediatric Emergency Department.

Heart Condition During Shock

Shock can be thought of in terms of three key elements that affect the heart’s ability to provide an adequate circulation, namely preload, contractility and afterload.

Preload

Preload refers to the degree of tension placed upon the cardiac muscle as it begins to contract. It is usually considered to be the end-diastolic pressure at the completion of ventricular filling. A sufficient degree of stretch to the myocardium is required to produce a level of contraction as governed by the Frank-Starling mechanism. This stretch is produced by venous return, itself inherently linked to actual circulating volume. A fall in circulating volume will reduce venous return, myocardial stretch, force of myocardial contraction and cardiac output.

Contractility

The force generated during ventricular contraction defines ventricular contractility. Contractility is maximised in a neutral homeostatic environment when myocardial oxygen delivery is adequate, acidosis absent, electrolytes in balance, etc. Improvement in contractility increases cardiac output through improved stroke volume.

Afterload

Afterload may be thought of as the resistance against the heart as it exerts its force during contraction. It is actually the pressure created in the artery leading from the ventricle during ventricular systole. Whilst it is true that too high an afterload would result in a reduction in the output by the ventricle, too low an afterload itself poses significant problems since adequate organ perfusion relies on a finely balanced relationship between preload, contractility and afterload.

Management

Treatment of the victim of near-drowning can be attempted even before rescue from the water. Having said this, basic life support is difficult unless the rescuer has a firm foothold. Rescuers must always make a safe approach, otherwise further unnecessary deaths may occur.

Once on dry land the child’s airway should be opened and cleared but attempts at emptying the lungs of water are time wasting and fiitile. Fluid filled lungs have reduced compliance and so require higher inflation pressures. Resuscitation follows standard guidelines and most survivors will usually start to breathe after about 5 minutes.

The stomach is often full of water and vomiting often follows successful resuscitation attempts. Stomach decompression and intubation guards against this and both should be achieved once resuscitation has got underway. Once the child has been intubated, continuous positive airways pressure (CPAP) and positive end expiratory pressure (PEEP) are useful in ventilating stiff lungs.

Near-drowning can be complicated by a number of other factors, which must be borne in mind during resuscitation attempts. Many drowning incidents result from children falling or diving into water. In these circumstances the child could also have been injured and the rescuer should assume this until it can be ruled out. Particularly when there has been a diving accident in shallow water, there is significant risk of a cervical spine injury and the neck must be adequately immobilized until this possibility can be excluded.

The large surface area: volume ratio of children means that even during warm weather hypothermia is a common feature of near-drowning. A core temperature should be determined at an early stage during resuscitation using a low reading thermometer.

Hypothermia is a mixed blessing. Although its presence hampers resuscitation attempts, rapid cooling slows the metabolic rate and protects the vital organs. Children have survived long periods of submersion in cold water and resuscitation attempts should be equally prolonged. Survival has been recorded in children after an hour following submersion in cold water. Cardiac arrhythmias are frequently seen at low body temperatures, which also make them all the more difficult to treat. Ventricular fibrillation is often refractory at core temperatures below 30°C. Resuscitation should not be abandoned until the child has been rewarmed to at least 33°C. A child should not be declared dead until it is ‘warm and dead’.

Rewarming

The techniques used to rewarm a child depend on the degree of hypothermia. Methods are divided into external and core rewarming but must not hamper CPR.

External rewarming alone is usually adequate where core temperature is more than 32° C. Below 32°C, core warming is necessary. The means used depend on the skills of the rescuers and the facilities available

Means of external rewarming, temperature >32°C

• Remove wet clothing

• Dry child

• Wrap in warmed blankets

• Use radiant heat lamp

Means of core rewarming, temperature <32°C

• Infusion of warm intravenous fluids (at 43°C)

• Ventilation with warm gases (at 43°C)

• Instillation of warm fluids into body cavities (at 43°C)*

• Cardiac bypass

*Instillation of warm fluids into body cavities is used by some, but thought to

confer no advantage to others.

Indicators of outcome

Abandoning resuscitating is always a difficult decision and should ideally be made by a senior doctor. As already mentioned, despite an initially poor outlook, children have still survived. A number of factors may help when coming to a decision. The majority of successful resuscitations occur in children who have had submersion times of less than 10

minutes

Indicators of good outcome

• Submersion for <10 minutes

• Submersion in cold water

• Initial core temperature below 33°C preserves vital organ (especially brain)

function

• Initial spontaneous breath in first few minutes

Indicators of poor outcome

• No spontaneous respiratory attempt within 40 minutes

• Arterial pO2 less than 8.0 kPa (60 mmHg) despite resuscitation

• Blood pH below 7.0 despite resuscitation

• Persisting coma

Definition

Drowning is defined as death by asphyxiation following submersion in a fluid, which is usually water. During the initial resuscitation it does not seem to make any difference whether this is fresh or salt water. Near-drowning occurs when the victim recovers, however briefly, following submersion.

Epidemiology

Bodies of water act as a strong draw for children and are a favored play area. Every year hundreds of children drown and this is a significant cause of death particularly in the under 4–year-olds who are often oblivious to the potential dangers. Carers should be ever mindful of this and should never leave children unsupervised especially if they suffer with epilepsy. Whether it be the garden pond or the unattended bathtub, they are all potential death traps. Children should be encouraged to learn to swim from an early age.

Pathophysiology

In drowning accidents, the primary event is a respiratory arrest eventually leading to a secondary cardiac arrest. A child submerged in water will initially hold their breath and their heart rate slows as part of the diving reflex. If this process continues, hypoxia develops and the child then becomes tachycardic. Eventually the child will take a breath and inhale water, which on contact with the glottis results in laryngospasm and secondary apnoea. In about 10% of cases no water actually enters the lungs in what is known as ‘dry drowning’. In the remaining cases, secondary apnoea is followed by the disappearance of laryngeal spasm and the development of involuntary respiration. Water and debris are then drawn down into the lungs. The child becomes progressively more hypoxic and acidotic, with a terminal bradycardia or arrhythmia acting as the prelude to eventual cardiac arrest.

Anaphylaxis Shock Resuscitation in Pediatric

Anaphylaxis is a potentially life-threatening systemic allergic reaction mediated by IgE antibody, resulting in the release of histamine, leukotrienes and vasoactive mediators. The commonest etiologies are specific environmental allergens, e.g. food, insect bites, drugs, blood products and radiocontrast media. Most reactions occur within 30 minutes of exposure and require prompt assessment and aggressive treatment.

Signs and symptoms

A prodrome of flushing, facial swelling, urticaria, wheeze and stridor may precede airway obstruction or shock.

Life-threatening features of anaphylaxis and their cause:

Feature Cause ---> Stridor Laryngeal and pharyngeal edema (tongue, lips and uvula)

Cough and wheeze ---> Bronchospasm

Hypotension ---> Systemic vasodilatation and hypovolemia (capillary leak)

The child may also have pruritis, nausea, vomiting, abdominal cramps and diarrhea.

Immediate management

Epinephrine (adrenaline) and the ABC approach are the mainstays of treatment.

Epinephrine

Give epinephrine (adrenaline) s.c. i.m. (0.01 ml kg−1 of 1:1000) or slowly i.v. (0.1 ml kg−1 of 1:10000)

Improvement should be seen within 2 minutes. The dose of epinephrine (adrenaline) should be repeated if the effect is incomplete.

Airway/breathing

The child should be given:

• oxygen by facemask

• nebulized epinephrine (adrenaline) 5 ml of 1/1000 may be used in conjunction with intravenous epinephrine, or alone for mild upper airway obstruction

• intubation if airway obstruction is severe

Call for urgent anesthetic and ENT assistance as the child may need urgent intubation and, very rarely, a surgical airway.

Circulation

Intravenous access should be secured with a wide bore cannula. Circulation should then be supported.

• Give 20 ml kg−1 of normal saline, for hypotension.

• If hypotension continues, give further fluid bolus of 20 ml kg−1 and not colloid doses and repeat epinephrine (adrenaline) dose every 5 minutes or consider i.v. epinephrine (adrenaline) infusion 0.1 µg kg−1 min−1 with the child on continuous oxygen saturation, ECG and BP monitoring. Senior emergency and intensive care staff should be called.

Further management

All patients with anaphylaxis should be admitted for observation as they may deteriorate after the initial episode. They may need further treatment, including:

• steroids: hydrocortisone 4 mg kg−1.

Choking Treatment in Pediatric

Every year, hundreds of children die, particularly in the preschool age group, after inhaling a foreign body, the commonest cause of accidental death in the under 1-year-old group.

[1] Consumer product safety standards have helped decrease this number by dictating the minimum size of toys and their components suitable for this at-risk under 4-year-old age group,

[2] or by modifying previously dangerous items such as ballpoint pen tops. In addition, responsible manufacturers have withdrawn some of the dangerous elements of their product range. Tragically, however, children still choke on a host of things around the home, including food such as hot dog, crisps, nuts and buttons with resultant avoidable deaths. Small children will put almost any object in their mouths and the potential for a choking accident always exists.

Diagnosis

The diagnosis of foreign body inhalation is not always obvious, especially if unwitnessed. It should be suspected in any infant or child who develops sudden onset respiratory distress, particularly if associated with coughing, gagging, stridor or wheeze. A collapsed apnoeic child with foreign body aspiration may also present with a chest that cannot beinflated despite adequate airway opening manoeuvres and rescue breaths. The differential diagnosis includes a number of important infections, such as croup and epiglottitis with upper airway edema and obstruction. They should be suspected in children who, in addition to upper airway obstruction, present with features such as fever, lethargy, hoarseness or drooling. Incorrect diagnosis leading to inappropriate management can be disastrous and may result in worsening obstruction and possible death. These children should be taken to an appropriate hospital facility as a matter of urgency.

Small inhaled objects may well pass down into the distal bronchial tree and, if a careful history and examination are not performed, they could be mistaken for asthma. Unilateral wheeze and air trapping on chest X-ray are helpful clues. Bronchoscopic retrieval of even a small asymptomatic foreign body is necessary to prevent infection developing.

Treatment

A child suspected of foreign body inhalation should be managed as a priority in a calm and reassuring manner. When foreign body aspiration is either witnessed or strongly suspected and the child is still able to cough, he or she should be encouraged to do so for as long as a forceful cough is maintained.

In the absence of an effective cough or respiratory effort with the development of stridor, cyanosis and unconsciousness and in the presence of obstructed breathing, other techniques are used to try and dislodge an inhaled foreign body. The technique depends on the age of the victim. They are all designed to create an artificial cough by rapidly increasing intrathoracic pressure, thereby expelling air to expel the foreign body.

Blind finger sweeps in a child’s mouth are not recommended and should not be performed. They are likely to cause the child to panic all the more or even push a foreign body at the back of the throat further down into the airway making it more difficult to remove. In addition the soft palate is easily damaged and blood tracking down into the airway increases obstruction.

In the unconscious apnoeic child, airway opening manoeuvres should be performed. In addition to the standard techniques, the tongue-jaw lift is useful and is achieved by grasping the tongue and lower jaw between finger and thumb and pulling forwards. This pulls the tongue off the back of the throat and may relieve the obstruction and make visualisation of a foreign body easier. If the foreign body is visible it should be removed preferably with Magill’s forceps.

a. Infants

A combination of back blows and chest thrusts only is recommended in this age group. Infants have a relatively large liver and abdominal thrusts could potentially result in abdominal injury.

The rescuer should place the baby prone and head down over the outstretched arm with the forearm resting on the thigh, supporting the baby’s head. Five back blows, with the heel of the free hand, are then delivered between the baby’s shoulder blades. Should this be unsuccessful the baby is turned over, again head down and cradled on the outstretched arm. Five chest thrusts are then delivered using the same landmarks and techniques as for cardiac massage, only more slowly. Larger infants can be dealt with the same way but with the child resting over the lap.

b. Children

In the older child, back blows are carried out as in the larger infant with the child lying over the lap. If the victim is conscious, abdominal thrusts (the Heimlich manoeuvre) [3] can then be used with the child sitting, standing, lying or kneeling. If unconscious, the victim should be managed lying in the supine position. When the child is in other than the lying position, the rescuer should stand behind and place the arms around the child’s torso with a clenched fist against the abdominal wall between the xiphisternum and umbilicus. The other hand is then placed over the fist and both hands are thrust rapidly upwards into the abdomen. This is performed five times or less if the foreign body is expelled.

To carry out abdominal thrusts with the child lying supine, the rescuer kneels to one side or astride the child and places the heel of one hand on the abdominal wall between the umbilicus and xiphisternum. The free hand is then placed onto the first hand and five vigorous midline upward thrusts are carried out or until the foreign body is expelled.

Post-resuscitation Stabilization in Pediatric Cardiopulmonary Emergency

Following the return of spontaneous circulation, damage still continues by way of reperfusion injury, hence stabilization is essential. The child will need complete ventilatory support until cardiac stability is achieved in a designated intensive care unit.

Often inotropic support with dopamine, dobutamine and epinephrine (adrenaline) will be required in the immediate post-arrest state to maintain adequate tissue perfusion.

The patient needs monitoring and investigations

Monitoring
• Pulse and rhythm
• Invasive and non-invasive blood pressure monitoring
• Respiratory rate
• Pulse oximetry
• Transcutaneous CO2 monitoring
• Arterial blood gases
• Skin and core temperature
• Central venous pressure
• Urine output

Post-resuscitation investigations
• Full blood count
• Urea, creatinine and electrolytes
• Liver function tests
• Blood glucose
• Arterial blood gases
• Clotting
• 12-lead ECG
• Chest X-ray

The facilities for these may not be readily available until transfer to the intensive care unit but the following investigations should be carried out immediately post-resuscitation.

Pediatric Cardiopulmonary Emergency Drugs

In a cardiorespiratory arrest, drugs are usually given intravenously. However, prior to obtaining vascular or intraosseous access, many drugs can be administered via the tracheal route, namely epinephrine (adrenaline), lignocaine, naloxone and atropine. At least two to three times the intravenous dose, and, in the case of epinephrine (adrenaline), 10 times, the dose should be mixed with 2–3 ml of 0.9% saline. The dose is usually administered via a tracheal suction catheter, which is advanced past the trachea in order to maximise delivery of the drug. This route is a lastresort drug delivery and absorption from this route is very unpredictable.

Atropine

Persistent myocardial hypoxia results in bradycardia, which, left untreated, will lead to a cardiopulmonary arrest Atropine in a dose of 20 µg kg−1 is useful to antagonise the vagally induced bradycardia during tracheal intubation. The pupils should be examined prior to the administration of atropine as it causes bilateral pupillary dilatation and hence interferes with neurological assessment in head injuries.

Epinephrine (adrenaline)

Despite experience with cardiopulmonary resuscitation over the last 30 years,epinephrine (adrenaline) still remains the sole drug effective in restoring circulation in patients following cardiac arrest. Its alpha-receptor activity is thought to be responsible for increasing the aortic diastolic pressure and subsequently coronary artery perfusion. Peripheral arterial vasoconstriction increases the afterload and myocardial perfusion but also has a tendency to increase myocardial oxygen demand. Enhancement of the contractile state of the heart and stimulation of spontaneous cardiac contractions is responsible for the successful return of circulatory activity. It has been postulated that a drug with pure alpha-receptor agonist properties may in fact be more effective, but studies comparing epinephrine (adrenaline) with norepinephrine (noradrenaline) have shown no clear benefit.

Sodium bicarbonate

Metabolic acidosis rapidly develops during cardiopulmonary resuscitation as a result of anaerobic metabolism owing to the absence of oxygen. Myocardial contractility is inevitably depressed by this state of acidosis. The use of alkalising agents, namely sodium bicarbonate, is not routinely recommended in the initial stages of resuscitation as it can produce a transient increase in intracellular acidosis. The generation of carbon dioxide, whose elimination is already impaired will result in a left shift in the oxygen dissociation curve and further limit the supply of oxygen. Sodium bicarbonate can reliably be used in the treatment of hyperkalemia and, as worsening acidosis renders epinephrine (adrenaline) ineffective, its use may be advocated if return of spontaneous circulation has not occurred after the second dose of epinephrine (adrenaline).

Fluid administration

In the pre-arrest state, the tissues are often poorly perfused and administration of 20 ml kg−1 of crystalloids (0.9% saline) or colloid (4.5% human albumin solution) as a fluid bolus will result in rapid expansion of the circulatory volume. The controversy regarding crystalloid versus colloid administration in resuscitation will continue until published

evidence is available.

Glucose

Once vascular access has been obtained, blood should be taken to check the blood glucose as hypoglycemia (<3 mmol l−1) can develop following cardiac arrest. Prompt correction with 5 ml kg−1 bolus of 10% dextrose is essential as the hypoglycemic state may worsen neurological outcome.