Abstract
Anesthesiologists are likely to face pediatric disaster victims both in the developed world and in developing countries, as children are a significant percentage of the global population. Although many challenges in taking care of children in disasters, especially in resource-poor countries, are like the ones described elsewhere in this book, pediatric disaster preparedness involves some unique considerations. The following provides a brief overview of essential equipment, training, and resuscitation as applicable to the anesthesiologist caring for a child in a disaster.
Introduction
Anesthesiologists are likely to face pediatric disaster victims both in the developed world and in developing countries, as children are a significant percentage of the global population. Although many challenges in taking care of children in disasters, especially in resource-poor countries, are like the ones described elsewhere in this book, pediatric disaster preparedness involves some unique considerations. The following provides a brief overview of essential equipment, training, and resuscitation as applicable to the anesthesiologist caring for a child in a disaster.
Pre-Operative Evaluation
As most pediatric drugs are weight based, obtaining an accurate weight prior to surgery is important. In the event a measurement is not available (due to absence of scales or presence of injury), there are multiple strategies for estimating weight:
Broselow tape: Color-coded tape measure that estimates a child’s weight based on length. The tape measure also lists medication doses and equipment sizes.
Best Guess: Australian formula that estimates weight:
infants 1–11 months: weight (kg) = (age in months+9)/2
children 1–4 years: weight (kg) = 2 × (age +5)
children 5–14 years: weight (kg) = 4 × age
The advanced pediatric life support (APLS) formula:
infants 0–12 months: weight (kg) = (0.5 × age in months) + 4
children 1–5 years: weight (kg) = (2 × age in years) + 8
children 6–12 years: weight (kg) = (3 × age in years) + 7.
For children < 1 year old, the Broselow tape is the most accurate, whereas Best Guess is most accurate for ages 1–5 years and 11–14 years and the APLS formula is most accurate for ages 6–10.1
Pediatric patients may present for a variety of procedures during disasters. In addition to immediate post-disaster trauma surgeries such as exploratory laparotomy for control of blunt abdominal trauma or craniotomy for hematoma evacuation, pediatric patients may present in the more sub-acute phase for reduction of long-bone fractures, or for surgery unrelated to the disaster, such as appendectomy. Even the most emergent of surgeries allow for at least a brief pre-operative evaluation:
1. Assessment of the airway including determination of structural derangements or bleeding which may make intubation difficult or impossible. The obtunded child at risk for aspiration requires immediate intubation even prior to surgery.
2. Assessment of circulatory volume: vital signs such as heart rate and blood pressure, as well as physical exam findings such as the strength of the peripheral pulse, duration of capillary refill, skin turgor, fullness of the anterior fontanelle, and mentation are invaluable in the assessment of volume status and shock. Signs and symptoms of shock include hypotension, rapid and weak pulse, restlessness, tachypnea, and diaphoresis. Internal hemorrhage is often more difficult to recognize than external hemorrhage.
The pre-operative evaluation prior to non-emergent surgery should include a thorough history and physical exam including:
1. Birth and postnatal history
2. Assessment of problems with prior anesthetics
3. Family history of problems with anesthesia
4. Drug allergies
5. Recent upper respiratory tract infection symptoms
6. Loose teeth
7. History of easy bruising or bleeding.
The child should be examined for mouth opening and neck extension, as well as a basic heart, lung, and neurologic exam. Depending on the nature of the surgery and the severity of the patient’s underlying illness, and pending available resources, laboratory evaluation and imaging studies may be necessary prior to surgery.
The recent or current upper respiratory tract infection in children presenting for elective surgery poses a dilemma for many anesthesiologists caring for children. On one hand, a recent viral infection places the child at increased risk of peri-operative respiratory complications; on the other hand, recent viral infections are frequently common in children, and an attempt to wait for recovery may be thwarted by recurrent infections. The presence of fever, purulent secretions, or active respiratory symptoms such as wheezing need to be factored prior to deciding whether to proceed. If the decision is made to proceed, the family should be counseled on the risks.
Whenever possible, parental consent should be obtained prior to surgery and anesthesia. For the unaccompanied child and in urgent or emergent situations, appropriate medical care should not be withheld. Non-urgent treatment may prove more difficult. Policies, whether on an institutional or national level, should be in place prior to deployment to disaster settings to address these issues and reduce confusion.
Pre-Operative Preparation of the Child
Pre-operative fasting guidelines are as follows in children:
1. Two hours for clears
2. Four hours for breast milk
3. Six hours for formula or a light meal
4. Eight hours for a heavy meal.
The anesthesiologist caring for children should be cautioned about the possibility of incomplete or inaccurate disclosure of fasting times by parents and information lost in translation. Appropriate precautions should be undertaken in these situations.
In non-disaster settings, surgery and anesthesia are very stressful experiences for children and their parents. This stress is undoubtedly amplified in the disaster setting. Young children between the ages of 1 and 5 tend to be at highest risk for developing significant pre-operative anxiety. Even in a disaster, steps should be taken to reduce or abolish this stress response through behavioral interventions and distraction techniques:
1. Distraction techniques are generally more effective than encouraging or consoling remarks.
2. Pre-operative anxiolysis with IV or PO benzodiazepines such as midazolam can be very effective.
3. Small doses of an anesthetic such as ketamine can be efficacious in the pre-operative period.
4. Opioids given alone as a pre-medication do not tend to allay anxiety, however, they should not be spared in the pediatric patient who has significant pain prior to surgery.
To the extent possible, during evacuation or transport, children should not be separated from their families or caregivers in the disaster environment. Should separation occur, reunification should be attempted as quickly as possible. The anesthesiologist caring for children in a disaster should be aware of such reunification resources.
Monitoring
The American Society of Anesthesiologists (ASA) standards for basic monitoring apply also to pediatric patients and should be adhered to even in resource-poor settings. Occasionally, deviation from these standards may be necessary to provide essential care in a timely fashion. These decisions should be a shared responsibility of the team where urgency, locally applicable guidelines, and alternative facilities with better resources form part of the risk/benefit calculation. The experience of the anesthesiologist in low-resource settings becomes very important in guiding these difficult decisions.
Oxygenation
When an anesthesia machine is used to deliver general anesthesia, an oxygen analyzer should be used to measure the concentration of delivered oxygen in the patient breathing system. Blood oxygenation should be measured via continuous pulse oximetry.2 In resource-poor or devastated areas, pulse oximetry may be unavailable or unreliable. The LifeboxTM project is a non-governmental organization that has delivered pulse oximeters to more than 100 countries to address this need. The aim is to make surgery safer by eliminating the need to conduct any anesthetic without pulse oximetry.
Circulation
Arterial blood pressure and heart rate should be determined at least every 5 minutes. Additionally, circulatory function should be continually evaluated by one of the following:
1. Palpation of a pulse
2. Auscultation of heart sounds
3. Monitoring of intra-arterial pressure tracing
4. Pulse oximetry.2
Automated oscillometric blood pressure cuffs are preferred, but manual sphygmomanometer measurements suffice if unavailable.
Electrocardiogram
Every patient receiving general anesthesia should have the electrocardiogram displaying continuously from the beginning of anesthesia until preparing to leave the anesthetizing location.2
Ventilation
All patients under moderate or deep sedation or general anesthesia should have continual monitoring for the presence of expired carbon dioxide. When an endotracheal tube or laryngeal mask airway is used to support ventilation, quantitative monitoring of expired carbon dioxide is recommended.2 In the disaster setting, this technology may have limited availability, and one expired carbon dioxide monitor may need to be shared by more than one operating room for critical parts of the case, such as during airway placement.
The Precordial Stethoscope
A precordial stethoscope will allow for continuous assessment of heart sounds, as well as breath sounds, complementing other monitors. It becomes especially useful if other monitoring modalities are unavailable. Every anesthesia provider traveling to a disaster area is advised to invest in a customized earpiece (approximate cost $50) that makes using the precordial stethoscope comfortable and practical for long periods. Endobronchial intubation, unintended extubation, apnea, bronchospasm, and circuit disconnections can be instantly diagnosed in addition to significant drops in cardiac output by change in heart sounds or heart rate. The patient end of the system is easily fashioned with intravenous tubing and stethoscope chest pieces, though pediatric and infant-designed chest pieces are readily available. More expensive modern iterations are Bluetooth wireless-based technologies that require battery power.
Temperature
Every child receiving anesthesia should have temperature monitored when clinically significant changes in body temperature are intended, anticipated, or suspected.2 Skin temperature monitoring suffices if other monitoring modalities are not available. Neonates and infants are particularly at risk of hypothermia during surgery and anesthesia due to their thinner skin and large surface area relative to body mass. A variety of warming strategies are effective, including warming the operating room, overhead warming lights, forced air warmers, fluid warmers, covering exposed skin with plastic wrap, and warming mattresses.
Access
Peripheral Access
Peripheral access in infants can be particularly difficult as the amount and distribution of subcutaneous fat makes visualization difficult. The saphenous vein is often more easily accessible, and IVs can be placed when the vein is not visible. The IV catheter is inserted into the skin at a 10–20° angle just anterior to the medial malleolus and directed toward the back of the knee. Butterfly needles inserted into small veins are not adequate for infusions during surgery as they easily dislodge, but can be used for induction. Local infiltration with buffered lidocaine can be helpful prior to awake IV placements, even in young children. In particular, the smaller gauge needles (26 G or 27 G) are well tolerated. The following IV catheter sizes are typically utilized:
1. Neonates and small infants: 24 G. Larger catheters may run the risk of rupturing the vessel. 22 G catheters can be used in the saphenous vein.
2. Toddlers and small children: 22 G.
3. Older children and adolescents: 18 or 20 G.
Intraosseous Line
Consider intraosseous (IO) placement if IV access cannot be obtained after two attempts. Consult the specific IO device instructions for proper utilization of the device. The insertion site of choice in infants and children is the proximal tibia. Alternative sites include the distal femur or distal tibia. Any medication or resuscitation fluid can be delivered through an IO, including blood products. A vigorous flush of 10 ml of normal saline is required before the catheter will flow. An IO is typically not maintained for longer than 24 hours.
Central Venous Access
Central venous lines (CVLs) suitable for pediatric patients come in multiple sizes and lengths. The femoral, subclavian, and internal jugular veins may be accessed. The internal jugular is typically larger than the femoral, but access is often impeded due to the presence of a cervical collar in trauma patients. The subclavian has a higher rate of requiring multiple attempts, unintended arterial puncture, and higher rates of pneumothorax as compared to the internal jugular vein.3 For internal jugular catheterization, the catheter tip should ideally be at the superior vena cava–right atrial junction, just outside the heart. Typical CVL sizes and insertion depths for internal jugular catheterization are presented in the Table 10.1.
Table 10.1 Typical CVL sizes and insertion depths for internal jugular catheterization
| CVL size | Insertion depth | |
|---|---|---|
| Neonates and infants | 4 Fr | 5 cm |
| Toddlers and small children | 5 Fr | 8 cm |
| Older children and adolescents | 7 Fr | 10–12 cm |
Tools to Improve the Success of Venous Catheterization
Ultrasound guidance improves vascular access success rates in children.4 However, these may be unavailable in the disaster setting. Portable and handheld machines are becoming more readily available and economical, and disaster teams should strongly consider having at least one of these devices. Portable infrared-based vein finding technology is useful in small children. Warm packs are helpful in patients with decreased perfusion to the distal extremities.
Airway Management
Mask
Cushion seal facemasks of various sizes should be available for every anesthetic. A properly sized mask covers the nose and mouth without overlying the eyes or extending beyond the chin. The use of proper technique is important.
1. Avoid depressing the submental soft tissues of small children during a chin lift. This maneuver often closes the mouth in neonates and infants which can sometimes, but not always, be relieved by extending the neck.
2. In difficult mask ventilation situations in infants, perform temporomandibular subluxation by placing the 5th digit in the retromandibular notch and pulling the condyles in an upward direction. This anteriorly translocates the jaw and rotates the temporomandibular joint, which opens the mouth and pulls the tongue off the posterior pharyngeal wall.
Airway Adjuncts
Oral and nasopharyngeal airways of various pediatric sizes should be available for every anesthetic.
1. Estimate oral airway size by measuring the distance from the teeth to the base of the tongue. Too small an oral airway may push the tongue into the glottic opening, whereas too large an oral airway may push the epiglottis into the glottic opening, worsening airway obstruction.
2. Nasopharyngeal airways must be lubricated and inserted gently to avoid traumatizing the turbinates or adenoids. Estimate the proper length by measuring the distance between the patient’s auditory meatus and the tip of the nose.
Endotracheal Tubes
Endotracheal tube (ETT) sizing in the pediatric patient is typically based on age. The most frequently used formula is:
ETT size = age (in years)/4 + 4
Subtract 0.5 mm for a cuffed ETT
Neonates and infants – 3.0 to 3.5 ETT
Premature infants may require ETTs as small as 2.0
Depth of insertion (cm) = ETT size × 3
Cuffed ETTs have several advantages over uncuffed ETTs:
1. Fewer repeat intubations typically required as inflation or deflation of the cuff often will allow for an appropriate leak
2. Less contamination of the airway in patients at risk for aspiration
3. More precisely controlled ventilation is allowed
4. Improved ventilation in patients with poor lung compliance is allowed.
A variety of ETTs are available for special needs. Pre-formed oral or nasotracheal tubes may not be available in an austere setting. Double lumen tubes may also be unavailable for one-lung ventilation. The anesthesiologist may have to rely upon selective lung ventilation using a single lumen tube, or occlusion of a main stem bronchus with a 5 Fr Fogarty type balloon-tipped catheter.
Early intubation should be considered for burn patients at risk for inhalation injury. Signs and symptoms of inhalational injury include difficulty breathing or swallowing, hoarseness, stridor, wheezing, or singed nasal hairs, but history of smoke inhalation should prompt vigilance and early intervention.
Laryngoscopes
Standard straight and curved laryngoscope blades should be available for every anesthetic. The laryngeal opening in infants tends to be more cephalad and anterior, and so it is common to use a Miller 0 or 1, or a Phillips 1 to intubate the trachea of infants and small children. A Macintosh blade, with its curvature and wider spatula, may be more advantageous to control the tongue when intubating an older child. Multiple laryngoscope handles and backup batteries should always be available.
Care should be taken to keep the cervical spine immobilized during laryngoscopy in all trauma patients. Video laryngoscopes allow for visualization of the laryngeal opening with minimal, if any, neck extension. They are unlikely to be available in the austere disaster setting, however.
It should be noted that infants and young children desaturate quickly in the face of apnea due to several factors such as a low functional residual capacity (FRC), a closing volume of small airways that is often higher than their FRC, and their higher oxygen consumption as compared to adults. Airway considerations also differ from adults. Neonates and infants have:
1. A proportionately larger head and tongue
2. An anterior and cephalad larynx
3. An omega-shaped epiglottis.
These features must be considered during placement of an advanced airway. Shoulder rolls can prove to be a useful adjunct to help align the airway axes, but they can also result in hyperextension of the neck, making the direct laryngoscopic view more difficult.
Laryngeal Mask Airway
Pediatric-sized laryngeal mask airways (LMAs) should be available during every anesthetic. The smallest LMA is a size 1, and should be suitable for most neonates and infants. LMA sizing is available on most LMA packaging. The contraindications to LMA use are like those in adults.
Difficult Airway Equipment
The anesthesiologist providing care to children in disaster settings should be adept at rescuing the pediatric airway. Arguably the ability to effectively mask ventilate is the most important skill to master prior to taking on the responsibility of providing anesthesia to children. If a difficult airway is anticipated, the corollary to the “awake intubation” in the adult is the technique of maintaining spontaneous ventilation throughout induction. This is most safely accomplished using agents that do not suppress breathing, such as ketamine, dexmedetomidine, and volatile agents. It is extremely important to avoid neuromuscular blocking agents in the anticipated difficult intubation until the airway is secured. In the event of an unanticipated cannot intubate/cannot ventilate situation, the ASA difficult airway algorithm can be applied to children.5
A variety of portable video laryngoscopes are available and may serve as an important rescue device in the disaster setting. LMAs can also be used as a conduit for ETT placement in the difficult airway. This is most easily facilitated with flexible fiberoptic scope use, but understandably, this equipment may not be available in the disaster setting. The AirtraqTM (Prodol Meditec S.A., Vizcaya, Spain) is a disposable fiberoptic intubation device that can be used in difficult airway situations. Some anesthesiologists have successfully reused the disposable device after disinfection, making it a particularly attractive option for use in the resource-poor setting. The smallest blade is a size 0, which is suitable for neonates and fits as small as a 2.5 ETT.
Related posts:
Chapter 5 – Inhaled Anesthetics and Draw-Over Devices in Disaster Response
Chapter 4 – Total Intravenous Anesthesia in Disaster Medicine
Chapter 15 – Chemical and Radiologic Exposures in Trauma and Disasters
Chapter 16 – Pain in Disasters
Chapter 12 – High-Altitude Physiology and Anesthesia
Chapter 21 – Operation Tomodachi: Anesthetic Implications
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