Equipment guidelines: Pearls and pitfalls

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8 Equipment guidelines

Pearls and pitfalls

Chapter Contents

Resuscitation equipment

Normal vital signs

Initial ventilator settings

The paediatric resuscitation room

This section is intended to assist you by providing practical tips that are usually only learnt by experience. For all the disposable and reusable equipment, advice is given based on a combination of evidence, best practice, familiarity and availability of possible alternative options.

Resuscitation equipment

Laryngoscope blade

Traditionally, a straight blade (e.g. Phillips/Miller/Wisconsin) is advised when performing direct laryngoscopy in a child in order to control the large epiglottis. The reality is that either a curved (Macintosh) or a straight blade may be used, depending on the preference of the laryngoscopist. Similarly, the actual size of blade selected is not important as long as the cords are well visualized, dependent both on laryngoscopist comfort and on anatomical factors.

Endotracheal tubes – cuffed vs. uncuffed

A decade ago children were always intubated using uncuffed ETTs but recent research supports the routine use of cuffed ETTs in children over 6 months of age.

Advantages of a cuffed ETT:

• helps to prevent aspiration of gastric contents

• prevents the leakage of ventilation past the ETT leading to gastric insufflation

• the use of the exact size is less important than with an uncuffed tube.

Disadvantages of an uncuffed ETT:

• inability to accurately measure tidal volumes

• more prone to displacement in the trachea

• must fit tightly – recent evidence suggests that pressure-related complications might be higher with uncuffed tubes.

While preparing for the intubation, always have the estimated size ETT as well as tubes with an internal diameter 0.5 mm smaller and 0.5 mm larger than the expected size available. Length-based resuscitation tapes are more accurate than age-based formulas in estimating the ETT size for children up to approximately 35 kg. The size of the nostril or the little finger should never be used.

ETT cuff pressures must be monitored with a cuff pressure manometer as subjective assessment of cuff pressure is totally unreliable. Pressures should be kept less than 20 cm H₂O and just enough to ensure that there is no leakage of air during positive pressure ventilation.

ETT depth

Unlike adults, the correct position of the ETT is in the mid-trachea. Although most texts suggest that ETT position should be guided by ensuring that the two transverse cord marker lines on the ETT are positioned at the level of the child’s vocal cords, the position of these lines can be variable, depending on the manufacturer, and is therefore not advised. Formulas for depth of insertion are often promoted but still are probably not the most accurate way of estimating depth. A useful rule of thumb is to convert the ID into a distance in centimetres that the ETT should be passed distal to the vocal cords. This will apply to both the full size and half size ETT: the tip of a size 4 and 4.5 mm ID ETT should be positioned 4 cm distal to the vocal cords. The technique of using palpation of the ETT in the neck to estimate the depth of insertion is unreliable and should not be used. Depth can be maintained consistently via in-line immobilization of the head and appropriate padding behind the torso or head, depending on age. Any flexion, extension or lateral movement of the head can lead to ETT displacement.

Introducer (stylet)

An introducer should be used in all intubations unless a bougie (tracheal tube introducer) is going to be used. Ensure that the tip of the introducer does not protrude past the tip of the ETT as this may cause trauma to the airway. Bend the tip to about (but no more than) 30° to optimize the chances of first-time intubation success. It is worthwhile to lubricate the stylet prior to inserting it into the ETT to aid in its removal postintubation.

Bougie (tracheal tube introducer)

A bougie should be readily available. This is an intubating stylet that is longer than the standard ETT introducer. A suitable water-based lubricant (or lidocaine spray) should be used for ease of insertion and removal of the bougie once intubation is achieved. Although useful as an adjunct for difficult airways (e.g. Cormack Lehane Grade 3A), the device may be used on easier airways in order to practise and maintain the skill for when it is truly required.

Oropharyngeal airway

The Guedel airway and the Berman airway are two versions of this commonly used device. It is a useful airway adjunct to open an airway in unconscious bag–mask ventilated patients. The size can be estimated by measuring from the corner of the mouth to the angle of the mandible. During insertion the tongue should be controlled by a tongue depressor or laryngoscope blade while inserting the airway along the curvature of the pharynx. Do not insert the airway upside-down and rotate it in the mouth as this can cause trauma to the pharynx.

Nasopharyngeal airway

A nasopharyngeal airway is a valuable adjunct in patients who are unconscious or semi-conscious. A well-lubricated airway can be inserted with the bevelled edge aligned with the septum of the nose. This avoids trauma to the turbinates as well as the nasal septal mucosa. Care should also be taken to ensure that it is inserted parallel to the floor of the nasal cavity to avoid trauma to the turbinate mucosa. Do not use if a base of skull fracture is suspected. There is no evidence to suggest the optimum measurement for nasopharyngeal airway size. The distance from the nostril to the ipsilateral tragus is commonly used.

Bag–valve resuscitator

The bag–valve resuscitator must be tested before use. This can be done in the following easy steps:

1. Place a hand underneath the patient-connection end.

2. Squeeze the self-inflating portion of the bag and check that air is expelled.

3. Seal the patient-connection end with the palm of your hand.

4. Squeeze the self-inflating portion of the bag and check that there is no leakage in the rest of the bag.

5. If a pop-off valve is present, perform the abovementioned steps first with the valve open, and secondly with the valve closed.

6. Lastly, the reservoir should be attached to the patient-connection end and held in place while the self-inflating portion of the bag is squeezed repeatedly. This should inflate the reservoir bag completely, and reveal any leaks in the reservoir. This also exposes any fault with the one-way non-return valve of the bag–valve resuscitator: if the reservoir inflates and deflates, this may indicate that the one-way valve is dysfunctional.

The infant bag–valve resuscitator should be used on children less than 10 kg. The paediatric bag–valve resuscitator can be used on patients weighing 10–39 kg. The adult bag can be used on patients weighing more than 40 kg. The adult bag can be used on patients weighing less than 40 kg – during ventilation the bag–valve resuscitator should be compressed only with the force required to obtain adequate chest rise.

The oxygen flow rate should be sufficient to ensure that the reservoir bag does not fully collapse at any stage through the respiratory cycle. This flow rate will vary depending on whether an infant, paediatric or adult bag is used. The pop-off valve is designed to prevent pressures in excess of 35–45 cm H₂O from being transmitted to the child’s lungs. Certain circumstances may require the pop-off valve to be disabled or locked, such as the ventilation of an asthmatic child with bronchospasm. The high airway pressures will trigger the pop-off valve without allowing adequate ventilation.

Oxygen flow is limited by the duckbill/fishmouth valve at the patient-connection end of the bag–valve resuscitator. It also increases the patient’s work of breathing in spontaneously breathing patients. Hence the healthcare provider must compress the self-inflating portion of the bag–valve resuscitator in time with the patient’s respiratory effort in order to deliver a sufficient flow-rate of oxygen to the child.

The head and neck of the child should be placed in a neutral ‘sniffing’ position. Hyperextension should be avoided as this can compromise the airway. The proportionately larger head in neonates and infants can lead to flexion of the neck. This can be overcome by placing some padding/linen underneath the shoulders of the infant to lift up the body relative to the head, and to decrease lower cervical spine flexion. The pre-school child (between 1 and 6 years of age) is well-positioned with their head flat. The child over 6 should be positioned with the usual padding/linen under the occiput to achieve the ‘sniffing’ position.

Mask

Younger children do not have adequate development of their facial features to support an anatomical triangular mask. Hence a round mask is used for children less than 10 kg or less than 1 year of age. The bottom line, however, is to use whichever mask that fits correctly and allows for successful bag–mask ventilation.

Suction catheter

During laryngoscopy, a rigid suction catheter with a non-traumatic tip should be used in order to accurately direct suctioning. If there is a controlling thumb port, remember to occlude this during suctioning attempts. The size given in the text is for soft suction. Use the largest possible suction catheter that can fit through the ETT. Ideally, a closed system should be employed. This helps to prevent loss of PEEP as well as maintaining better infection control. Suctioning may cause vagal stimulation because of contact of the suction catheter with the pharyngeal, laryngeal or tracheal mucosa. If bradycardia ensues, remove the suction catheter and resume ventilation until the heart rate recovers to normal. Make sure that hypoxia from a displaced ETT is not the cause!

Heat–moisture exchanger

The smallest appropriately-sized HME must be used. This helps to minimize dead space ventilation. This fact is often ignored in children. An increase in dead space ventilation leads to hypercarbia, which in turn causes acidosis and vasodilatation which may lead to haemodynamic collapse or even cardiac arrest. Do not use other connective tubing as this also adds to the dead space.

Intercostal drain size (thoracostomy tube)

The largest size drain that will comfortably pass between the ribs should generally be used, although a smaller size can be used for a simple pneumothorax. Tubes should be inserted to a depth that allows for all the drainage holes to be in the chest cavity. Never use a trochar to introduce an intercostal drain. The pressure required to insert it may not be controllable, leading to the disastrous complications of iatrogenic penetrating trauma.

Urethral catheter

If an appropriate size cannot be found, a neonatal feeding tube can be used in an emergency situation. In uncircumcised male children, the foreskin may not be able to be fully retracted – do not force it.

Intraosseous needle size and depth

In an emergency setting, intravenous access can be difficult in adults but even more so in children. Intraosseous access, using a sterile technique, should be obtained after one or two rapid attempts at obtaining IV access (although the amount of time spent on attempting IV access depends on the urgency of the clinical situation). Intraosseous administration of drugs is easy and as effective as intravenous administration. The depth given in this book is based on the skin over the bone being compressed for the measurement and applies to the proximal tibial site only.

Nasogastric tube

A nasogastric or orogastric tube should be inserted postintubation. It aids in decompressing the stomach, which can interfere with ventilation and also cause a bradycardia via vagal stimulation. Orogastric tubes are preferred because of the lower incidence of unwanted side effects.

Intravenous access

Intravenous access can be difficult at times – especially in an emergency setting. Do not waste valuable time in this instance. A maximum of two attempts should be made at IV access before making use of the intraosseous technique. Insertion can be aided with the use of an ultrasound machine. If a vessel cannot be visualized with ultrasound, cannulation is unlikely.

Blood pressure cuff

This should ideally be placed around the child’s arm and not the leg. An oversized cuff will under-read the BP and an undersized cuff will over-read the BP. An appropriately sized cuff (cuff bladder encircling at least 80% of the arm and extending over 50–75% of the length of the arm from the axilla to the antecubital fossa) should be used to ensure accuracy.

Laryngeal mask airway and laryngeal tube airway

Both these supraglottic devices can be used in the event of a failed intubation. Caution is advised if the patient has severe bronchospasm, facial trauma, pharyngeal pathology (e.g. epiglottitis) or limited mouth-opening. Although conditions requiring higher ventilation pressures are a contraindication to using these devices in adults, supraglottic airways may be effective in these conditions in children.

Central venous catheter size and depth

Central venous access may be useful in children and the access techniques are similar to those used in adults. Femoral and internal jugular vein central venous access should ideally be performed via ultrasound guidance. If fluid volume administration is required, use the largest and shortest catheter possible. The depth of insertion of the CVC may be estimated by the formula:

Alternately, the depth may be estimated from the distance from the puncture site to the right 3rd costochondral junction.

Normal vital signs

With reference to the Charts in Chapter 5.

Average BP

This is the average expected BP for a patient. It is the 50th percentile for expected age.

Maximum BP

This is the BP on the 95th percentile for expected age. BPs higher than this should be considered to be suggestive of hypertension.

Minimum BP

This is the BP on the 5th percentile for expected age. BPs lower than this should be considered to be hypotension.

As per the recommendations released by the American Heart Association, hypotension is defined as a systolic blood pressure:

• <60 mmHg in term neonates (0 to 28 days).

• <70 mmHg in infants (1 month to 12 months).

• <70 mmHg + (2 × age in years) in children 1 to 10 years.

• <90 mmHg in children ≥10 years of age.

Recent data suggest using 65 mmHg instead of 70 mmHg for children 1–10 years of age.

The interpretation of vital signs, especially blood pressure, is not completely dependable in children because of the wide range of normal values. Other indicators of cardiac output (such as heart rate, capillary refill time, level of consciousness and urinary output) should also be used instead of relying on BP alone.

Heart rate

The 5th, 50th and 95th centiles of heart rate are shown.

Respiratory rate

The 5th, 50th and 95th centiles of respiratory rate are shown.

Urine output

Expected urinary output is about 2 mL/kg infants and 1.5 mL/kg for children.

Peak expiratory flow rate

These predicted values were obtained using a formula that predicts the 50th centile of PEFR in children (see Chapter 9).

Body surface area

This is an estimated BSA for children of this size on the 50th centile for weight and height.

Initial ventilator settings

FiO₂

The patient should initially be placed on 100% oxygen. This should be reduced as soon as possible according to the arterial blood gas PaO₂ in order to give the lowest possible FiO₂ that will maintain the PaO₂ above 60 mmHg. This helps to reduce the amount of superoxide free radicals which can cause damage.

Respiratory rate

This needs to be adjusted according to the patient’s condition, arterial blood gas PaCO₂ level and desired minute ventilation.

Positive end expiratory pressure

This is the pressure used to maintain the patency of the alveoli. Caution is advised in patients with bronchospasm due to the potential for auto-PEEP. PEEP is potentially deleterious for patients who are hypotensive or in cardiac arrest because of decreased venous return and cardiac output.

Inspiration : expiration ratio

The standard setting is 1 : 2 or 1 : 3. Normalization (1 : 1) or even reversal (2 : 1 or 3 : 1) of the ratio may be attempted if oxygenation is difficult.

Inspiratory time

The part of the respiratory cycle spent on inspiration.

Pressure support/assisted spontaneous breath and peak inspiratory pressure

PS and ASB are different terminologies for equivalent breaths which will support the patient’s own spontaneous breath and/or the ventilated breath, depending on the primary mode of ventilation chosen.

Some ventilators work on the following principle:

where the PS/ASB would be equivalent to the driving pressure.

It should be noted whether the ventilator is applying the PS/ASB above the allocated PEEP (as above) or using it as the Peak Inspiratory Pressure (PIP), thus making the actual driving pressure (PS/ASB − PEEP). The maximum driving pressure should be 18 cm H₂O based on adult studies.

Inspiratory pause/T_Plateau

This is the potential time between inspiration and expiration. If increased, it can assist in improving oxygenation by allowing for more time for gaseous exchange.

Flow (pressure) trigger

The trigger allows for the adjustment of the ease or difficulty with which a patient is able to take or trigger a breath when attached to a ventilator. The ventilator is able to detect whether the patient has initiated a respiratory effort either by a change in flow or a change in pressure within the circuit. A trigger that is set too high or too low can lead to patient–ventilator asynchrony.

Inspiratory gas flow and waveforms

The flow rate at which the oxygen/air is delivered. The flow rate needs to be greater than the maximum possible inspiratory flow rate of the child. The waveform is the pattern of inspiratory gas flow. The pattern influences the distribution of the inspired gas. The decelerating-flow pattern is preferred in general for use in both adults and children. It delivers the maximum flow at the initiation of inspiration, when resistance is decreased. The flow then decreases during inspiration as delivered gas volume increases. Peak airway pressures are lower than in an accelerating waveform but mean airway pressures are higher.

Tidal volume

This is based on a low tidal volume lung-protective ventilation strategy using a tidal volume of 6 mL/kg. In acidotic children an initial tidal volume of 8 mL/kg may be delivered, which should be reduced as soon as possible.

Minute ventilation

Volume control – max plateau pressure

The maximum plateau pressure allowed in volume-controlled ventilation in order to avoid ventilator-induced lung injury.

Pressure control – peak inspiratory pressure

The maximum peak pressure allowed in pressure-controlled ventilation in order to avoid ventilator-induced lung injury.

The paediatric resuscitation room

The amount of equipment required in order to perform a full resuscitation on a paediatric patient is extensive. Instead of rushing to try and search for each weight-dependent component, it is much easier to pre-pack all the equipment for each weight group in its own box. There can be one box of reusable equipment and another for the disposable equipment for each weight group. Each weight group box should have an inventory which is checked along with the rest of the resuscitation equipment at each change of shift and should be replenished after use.

The box with reusable equipment should have the following contents:

• Weight measurement tape e.g. PAWPER/Broselow® tape

• Laryngoscope handles

• Laryngoscope blades

• Bag–valve resuscitators

• Masks

• BP cuffs

• Spare batteries and bulbs.

A typical weight group box will have the following disposable equipment:

Adequate preparation prior to necessity is the key to any resuscitation but in paediatrics is pivotal. Just familiarizing yourself with the equipment and its use, as well as having this reference text for the drug dosing, will help in mitigating your fear associated with resuscitating children.

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