Perioperative management of pediatric trauma patients.

Pediatric trauma presents significant challenges to the anesthesia provider.This review describes the current trends in perioperative anesthetic management, including airway management, choice of anesthesia agents, and fluid administration.The review is based on the PubMed search of literature on perioperative care of severely injured children.

INTRODUCTION

Traumatic injuries remain to be a major cause of death in children from 1 to 14 years old in the US. Forty-five percent of total mortality in this age group is due to trauma. Motor vehicle collisions (59% mortality from all accidents in age group 5-14), pedestrian and bicycle accidents, falls, burns, and physical assault are the most common causes of injury in children.[1] Many of injured children will require surgical treatment with involvement of the anesthesiologist.

The anesthesia providers may have to take care of pediatric patients on following occasions:

Initial stabilization in the emergency department

Providing sedation and monitoring for imaging

Emergent surgical procedures such as laparotomy or craniotomy

Semielective surgeries after initial stabilization such as long bone fracture fixations

Intensive care unit management of these patients

Pain control during hospitalization, especially using regional analgesia

Therefore, anesthesia providers should be familiar with the principles of management of pediatric trauma as well as with age-related specific anatomical and physiological aspects of trauma care.

ANESTHETIC MANAGEMENT

Preoperative evaluation and management

Whenever possible, a thorough history and medical examination should be conducted prior to anesthetic administration. However, in urgent procedures only brief history outlined by AMPLE mnemonic may be feasible.

A = Allergies

M = Medications

P = Past medical history

L = Last oral intake, last tetanus immunization

E = Events related to the injury

Clinical examination is the most important diagnostic tool in pediatric trauma.[2] In emergency, only a quick assessment of airway, breathing and circulation could be possible.

The preparation of the operating room should include stocking the anesthesia cart with age-appropriate equipment, diluting and labeling the medications in age-appropriate doses, and raising the ambient temperature to 26°C for infants and small children.[3]

Rapid-infusion devices, fluid warmers and infusion pumps should be available.

Imaging and laboratory testing may be very useful in injured children, but they should not delay emergent procedures. From all the chest imaging methods, standard anterior-posterior chest X-rays is a cost-effective screening tool that will reveal most of the thoracic abnormalities.[4]

Routine laboratory tests such as urinalysis or serum chemistries are rarely indicated in pediatric trauma. From the specific testing, type and cross match blood, and hematocrit are indicated for a hemodynamically unstable patient. Serial hematocrits may help in the monitoring of solid organ injuries.[5] Since coagulopathy is associated with trauma in general and with head injuries specifically,[6] PT, PTT, and INR are useful tests in critically injured patients.

Serial arterial blood gas testing is invaluable in assessing dynamic changes in hematocrit, oxygenation and acid-base status in critically ill children.

Airway assessment and management

Many of the trauma victims arrive to the emergency department already intubated. In this case the anesthesiologist’ duty is to assess the airway (tube size, cuffed/incuffed, presence and magnitude of air leak if uncuffed tube, depth of the tube, breath sounds, ventilation and oxygenation). Any chest X-ray done in the emergency department should be reviewed for the correct position of the tracheal tube in mid-trachea, and for the presence of pneumothoraces.

Children have high oxygen consumption rate, relatively low functional residual capacity, and rapid bradycardic response to hypoxia. They do not tolerate long apneic periods well. Therefore, thorough airway examination is crucial. The anesthesia provider should be prepared to encounter the following anatomical features of pediatric airway:

A large protuberant occiput creates the natural flexion of the head in young children. It predisposes the airway to obstruction, and requires careful positioning for intubation. In cases when neck stabilization is needed, a large occiput can make the airway management even more challenging.

A small oral cavity, large tongue, delicate easy-bleeding gums, the presence of adenoids and tonsils, and occasionally loose deciduous teeth may restrict intraoral manipulation, obstruct visibility with direct laryngoscopy, and create predisposition to easy bleeding.[7] Nasotracheal intubation or even use of a nasal airway can cause hemorrhage.

The larynx is short and positioned relatively high and more anterior. The epiglottis is often U-shaped, long, and floppy. This combination may pose potential difficulties with laryngoscopy, and a short larynx increases the possibility of endobronchial intubation.

One should also be aware of the fact that a pediatric airway is at its narrowest at the cricoid cartilage when choosing the endotracheal tube.

Equipment necessary for intubation include: functioning suction, age-appropriate tracheal tubes with stylets, functioning laryngoscope (straight and curved blades). A secondary device for tube placement confirmation (e.g., capnograph, colorimetric CO2 detector) should also be available. If the child needs to be intubated, he/she should be given 100% O2 prior to intubation to denitrogenate the lungs. This increases the O2 reserve and allows a longer period of apnea during intubation. The cervical spine should be protected with a spinal board and rigid collar. If an appropriate pediatric cervical collar is not available, rolled towels or blankets might be carefully placed on either side of patient's head in young children and infants. Peripheral intravenous or intraosseous access should be checked for correct positioning prior to injecting medications.

The pediatric trauma victims should always be considered as full stomach patients, and rapid sequence induction is preferred. Rapid sequence induction is a gold standard for airway management in these patients.[8]

Aerophagia and gastric inflation are characteristic for children with trauma and/or assisted ventilation with a bag valve mask. Besides, traumatic gastric paresis may significantly slow down gastric emptying even if the last meal was more than 8 hours ago. After initiation of sedation, cricoid pressure is recommended to prevent gastroesophageal reflux, though the utility of cricoid pressure is debated. Cricoid pressure is contraindicated in patients with suspected cricotracheal injury, active vomiting, or unstable cervical spine injuries.[9]

A sample protocol for rapid sequence intubation is presented in Figure 1.[10]

Figure 1

A potential scenario-based protocol for rapid sequence intubation in children. From Zelicof-Paul A, Smith-Lockridge A, Schnadower D, Tyler S, Levin S, Roskind C, et al. Controversies in rapid sequence intubation in children, with permission

Severely injured children may be intubated with either cuffed or uncuffed endotracheal tubes. The general opinion, however, is shifting in favor of using cuffed tubes, even in the prehospital settings.[1112] The size of the uncuffed tube is often determined by modified Cole formula (age [y]/4+4 mm ID), and is decreased by half-size for cuffed endotracheal tubes. The cuff should be inflated to get a seal at about 25 cm H2O of airway pressure.

Induction drugs may vary, but Etomidate 0.1-0.2 mg kg−1 is a preferable induction agent in hypovolemic patients with a head injury. Etomidate provides hemodynamic stability and decreases cerebral oxygen consumption, which makes it a desirable agent despite possible influence on adrenocortical system.

Benzodiazepines, ketamine, thiopental, and propofol can also be used when appropriate.[31314] Characteristics of induction agents appropriate for rapid sequence induction in children are represented in Table 1.[10]

Table 1

Characteristics of preferred intravenous sedative agents for rapid sequence induction

Fast muscle relaxation could be achieved with succinylcholine or rocuronium.

Alternative devices in case of failed laryngoscopy may include a videolaryngoscope[15] and laryngeal mask airway (LMA).[16] Fiber optic bronchoscopy and intubation may be performed later via the LMA.[17]

INTRAOPERATIVE MANAGEMENT

Monitoring should be adjusted to specific needs. Temperature monitoring is mandatory in all children due to their immature thermoregulation, disproportionately greater body surface area to body mass ratio and fluid and heat loss from exposed surgical sites. Children with a head injury may require arterial and intracranial pressure monitoring as well as neurophysiologic monitoring during surgery. Noninvasive monitoring devices, including continuous hemoglobin analysis and near infrared spectrometry, are being increasingly used in pediatric anesthesia and may have a role in the care of trauma patients.[18]

The maintenance of anesthesia should follow the principles of balanced anesthesia and provide adequate hypnosis, analgesia and muscle relaxation. No single technique is superior to others.[319] Isoflurane, sevoflurane, and continuous intravenous infusion of propofol and opioids have all been used safely.[20] However, the total intravenous anesthesia technique is gaining popularity, especially during neurosurgical procedures.[21]

Intraoperative fluid management

Physiologically, children compensate better hemodynamically in the early stages of injury. Hypotension is a late sign of hemorrhage in children that may not occur until 25-35% of the blood volume or more is lost.[22] Tachycardia is the first sign of hypovolemia in children, and it should not be overlooked, because children have small blood volumes (80 ml kg−1 in an infant 1-3 months old, 70 ml kg−1 in children older than 3 month[23] ), and delay in fluid resuscitation may lead to a significant hypovolemia fast.

All intravenous fluids should be warmed to 37° to prevent hypothermia.

Resuscitation routinely begins with clear fluid, isotonic crystalloids being the fluid of choice. The end-points of fluid resuscitation in children usually include normalization of pulse rate and urine output >1 ml kg−1 h−1.

Hypertonic saline was shown to increase hemodynamic stability and decrease fluid requirements in adult trauma patients,[24] but it did not affect the survival rate.[25] One might consider use of hypertonic saline when trauma is associated with a closed head injury;[26] however, more evidence for use of hypertonic saline in children is needed.[27] Hydroxyethil starch and albumin have also been used in children with no significant adverse effects.[2829]

Dextrose-containing fluids are usually avoided, because hypotonic solutions may contribute to the development of cerebral edema,[30] and also to avoid risk of hyperglycemia, which is associated with poor neurological outcome in children with a head injury.[31] However, hypoglycemia also is harmful for a suffering brain, and should be avoided.[32]

Guidelines regarding transition from clear fluids to blood and blood products are not well established in pediatric trauma. Clinical decisions either follow adult protocols, or are made per individual clinical judgment.[3334] Deciding on time and volume of blood transfusion may be difficult in children. Underresuscitation leads to impending shock, when hemodilution, coagulopathy, acidosis and transfusion-related complications are associated with excessive crystalloid infusion and administration of blood products. The concept of damage control resuscitation (DCR)[35] has been associated with improved survival and shorter hospital stay in adults.[36]

The core principles of DCR include rapid surgical control of bleeding, permissive modest hypotension that helps preserving the freshly formed thrombus, minimal use of isotonic coloids with prevention of hemodilution-related complications, and early administration of packed red blood cells (PRBC) in combination with plasma, and platelets in a 1: 1: 1 unit ratio.[37] Supplemental use of coagulation factors such as recombinant factor VII and or cryoprecipitate is advocated if appropriate. DCR may be applicable to pediatric traumatic hemorrhage;[34] however, more clinical data is needed.

As of now, recommendations on starting blood transfusion in injured children include administration of two fluid boluses of 20 ml/kg each followed by whole blood or packed red blood cells if no improvement in clinical status is seen.[38]

Massive transfusion may be required in cases of severe trauma. An example of massive transfusion protocol in a 5-year-old patient (70 ml/kg circulating blood volume) has been described as replacement for the first lost blood volume with crystalloid, 30 ml kg−1 PRBCs, and 20 ml kg−1 fresh frozen plasma. Each consequent circulating blood volume lost was replaced with PRBCs, fresh frozen plasma and platelets in a 3: 2: 2 volume ratio.[39]

Temperature control

The large surface to weight ratio predisposes children to heat loss. Immature thermoregulation mechanism and effects of general anesthesia can lead to rapid development of hypothermia.[40] Ambient temperature is an important factor influencing heat loss. However, maintaining the operating room at 30°C at all times can cause significant discomfort to a surgical team. Therefore, minimizing body exposure to ambient air and use of active warming are essential. Warming blankets, heated humidified air, and reduction of evaporative losses all offer modest benefits in reduction of heat loss. Convection heaters effectively warm children when body surface area uncovered is 20% or more.[41] Heat loss can also be prevented with administration of warm intravenous fluids.[42]

One should be aware of risk of hyperthermia with all warming techniques, therefore monitoring of core temperature is necessary.

EMERGENCE AND POSTOPERATIVE PERIOD

Most of the children with polytrauma will require monitoring and further stabilization in the intensive care unit (ICU) after the initial surgery. Significant fluid shift, acidosis, and soft tissue swelling could be anticipated with massive blood loss and aggressive fluid resuscitation. A combination of prolonged prone position and significant amount of intravascular fluids may cause airway swelling and abdominal compartment syndrome.[43] Many of these patients will require continuation of mechanical ventilation in the ICU. If decision on extubation in the operating room after polytrauma is made, it must be considered carefully. Longer cases and younger age were associated with early extubation failure after pediatric cardiac surgery.[44]

Successful extubation in patients receiving mechanical ventilation is dependent on cardiovascular stability, normal acid-base balance, presence of intact airway reflexes and ability to clear secretions, an intact central inspiratory drive, ability to exchange gases efficiently, and respiratory muscle strength to meet the work associated with respiratory demand.[45] Upper airway obstruction is the single most common cause of extubation failure.[46] In pediatric trauma patients, mechanism of injury (facial burn vs. other) and absence of an air leak at the time of extubation are the strongest factors predicting postextubation stridor. Patients with one or both risk factors require special attention to airway management and may not be good candidates for an early extubation.[47] Children who cannot be extubated immediately, will require transport to the intensive care unit and possibly to the imaging facilities.

Multiple mishaps with physiologic deterioration during transport have been described.[4849] Before transport, anesthesiologist should reassess the patient and ensure hemodynamic stability, adequate oxygenation, and functionality of the monitors. Intraoperative monitoring should be continued during transport, and the resuscitation drugs should be immediately available. A detailed report containing history and perioperative events must be given to the intensive care unit team, ensuring the continuity of care and patient safety.

Children, who were successfully extubated postoperatively, require a regimen of careful pain control. Treating pain may reduce anxiety and fear, which can themselves exacerbate pain.[50] It was shown previously, that very young children were more likely to receive inadequate analgesia compared with older children.[51] Acetaminophen is a commonly used drug. The recommended oral dosage is 10-15 mg per kilogram every four hours for children. Rectal administration produces delayed and variable uptake. Subsequent rectal doses should be smaller (e.g., 20 mg per kilogram), and the interval between doses should be extended to at least 6-8 hours.[52] Ibuprofen was shown to be more effective than acetaminophen in treating pain from musculoskeletal trauma.[53] In case more analgesia is needed, careful titration to effect of morphine or other opioids should be used. In infants 3-6 months of age, the analgesic effects of morphine or fentanyl are similar to, and the ventilatory depression is no greater than, that seen in adults with similar plasma concentrations.[52] Therefore, opioids should not be withheld in young children. Recently, regional anesthesia has been utilized with a great effect for post-operative pain treatment. Ultrasonographic guidance for a broad spectrum of regional anesthetic techniques results in safe and effective blocks of both upper and lower extremities.[5455] Ropivacaine and levobupivacaine are less toxic than bupivacaine, and can be safely used in children.[52]

SUMMARY

Trauma is a leading cause of morbidity and mortality in children. Anesthesiologists are widely involved in care of injured children during admission to the emergency department, surgical intervention, and postoperative care. Knowledge and understanding of different aspects of pediatric trauma allows anesthesia providers to be efficient and safe in their practice.