Good morning medical professionals,  

During the month of June, we will be discussing the topic of pediatric trauma. This week, we review the anatomical and physiological differences in the pediatric population.  

When attempting to manage a pediatric airway in the setting of a field trauma, the practitioner can expect a shorter upper airway with a less developed and more pliable trachea. The epiglottis is U-shaped and can be quite cumbersome with extraneous tissue. Coupled with a higher larynx, which is more anterior in nature than in adults, instrumentation of the airway in less-than-ideal conditions can be quite challenging. It is also worth noting that the pediatric heart is proportionally larger in the thorax, thereby costing the pediatric patient precious respiratory reserve, which should otherwise be present in adult patients. More horizontal ribs also contribute structurally to a natural inability for children to expand the anterior-posterior diameter of the chest cavity. Coupled with less developed accessory muscles than adults, the inability to expand the chest effectively is why a child’s respiratory rate is also higher, as this is the only way left for a child to account for a higher minute ventilation need. For these reasons, children are more sensitive to hypoxia than adults and show decompensation in a much shorter time period. An effectively ventilated pediatric patient, whether they have a definitive airway or not, will ultimately do far better in part due to the differences seen in respiratory dynamics in children.  

Circulation in the pediatric population has several caveats unlike those of adults. The pediatric heart has a natural inability to adapt inotropy mechanisms to support stroke volume, and cardiac output. Instead, it can only increase in chronotropy or rate. The pediatric heart is also an organ of low compliance; therefore, if a pediatric patient’s pulse is significantly greater than their normal age-adjusted rate, it signals impending circulatory failure. If progression to bradycardia occurs in the injured pediatric patient, this is regarded as an ominous sign and needs immediate intervention. Lastly, because of both difficulty with location and physical palpation, pulses should be palpated in the brachial artery to serve as the “periphery site” de facto. Capillary refill is also quite reliable as an adjunct to perfusion status in children. 

Other anatomic and resultant physiologic differences to appreciate in children is a body surface area ratio up to four times that of adults, with only a one-and-a-half-fold ability to produce heat to effectively avoid a hypothermic state. Immature musculature and less adipose tissue also account for an impaired shivering mechanism and diminished insulation ability. An immature liver leaves children at risk for profound hypoglycemia quickly, especially when the body is unusually stressed. A smaller abdominal cavity provides less potential space before impeding diaphragmatic excursion. Lastly, a blood volume of 70-80 cc/kg, depending on age up to a school age child, needs consideration as there is proportionally far less blood, and accordingly, less circulatory reserve in children based on their weight, than adults.  

Sincerely,

The UH EMS-I Team

Pediatric Airway -  June 14, 2021

Good morning,

For week 2 of our pediatric trauma series, we will discuss the pediatric airway.

As mentioned in last week’s posting, children can be difficult to intubate for multiple reasons. Some of those include differences in their head and neck, including a prominent occiput, large tongue, and small jaw. The large occiput causes passive flexion of the c-spine, so this interferes with the alignment of the oral, pharyngeal, and laryngeal axes when attempting to intubate, making visualization more difficult. The large tongue often completely obstructs the airway, making it difficult to visualize the larynx. The larynx in a child is more anterior than in an adult. The pediatric epiglottis is large and floppy and also Omega-shaped, making it more difficult to lift than in adults. The pediatric airway narrows at the cricoid ring, which is below the vocal cords. This means that unlike in an adult airway, if you were to intubate a pediatric patient, you may encounter resistance, so always make sure to have an endotracheal tube half size smaller next to your initial ETT size.

In a landmark randomized controlled paper, Gausche-Hill et al. examined 830 patients under 13 years-old who either were bag-valve masked (BVM) or endotracheally intubated (ETI) in Los Angeles and Orange County, CA., and 73% of these patients were under 3 years old. She found a 57.7% success rate and a 57.4% complication rate. The authors found no significant difference in survival (30% BVM vs. 26% ETI) or neurological outcome (23% BVM vs. 20% ETI). Among the misplaced tubes, 2% were esophageal; 6% were unrecognized displacements; 8% were recognized dislodged ETTs, and 18% were right mainstem intubations. The wrong ETT size was used in 24% of cases studied.

Pediatric intubation is difficult to a child’s inherent anatomy. Furthermore, it is one of those “high risk, low volume procedures” that prehospital providers encounter. Definitive care for any patient with a traumatic injury needs to occur within the “Golden Hour.” Accordingly, it is advisable not to spend extended time on scene attempting to intubate a pediatric patient, thereby delaying definitive care. Use an extraglottic airway or even BVM them all the way to the ED if need be.

Respectfully yours,

Jeffrey Luk, MD

Peds Trauma - June 21, 2021

Good morning,

Continuing with our topic of pediatric trauma, Part 1 of Tactical Emergency Casualty Care in the pediatric population.

Much like the guidelines originally outlined in Tactical Combat Casualty Care (TCCC), The Pediatric Committee for Tactical Emergency Casualty Care (C-TECC) guidelines advise, if possible, that the patient should move to a position of safety. If impossible or the patient is unresponsive, the risks and benefits should be weighed for rescue attempts in terms of the activity and safety of the situation at hand. The practitioner should realize that time may be more limited for pediatric patients in terms of rescue and medical salvage. Also similar to TCCC, C-TECC recommends prompt proximally placed tourniquets, hemostatic agents, and wound packing for hemorrhage control, especially in ongoing active threat scenarios. After moving the pediatric patient to an area of safety, reassessment of critical hemorrhage sites may be even more important than previously outlined guidelines due to the lack of reserves in pediatric physiology. Likewise, restoring circulating volume quickly to avoid losing reserve capacity is crucial in children due to their lower overall blood volume and their inability for the cardiac compensatory mechanisms to properly counter blood loss.

The C-TECC guidelines mention utilizing peripheral pulses and mental status in children, like in adults, as indicators of hemorrhagic shock. Restoring circulating volume to improve mental status, or as in the case of a patient with traumatic brain injury (TBI), to a goal of the age range appropriate mid-systolic blood pressure, is encouraged. For reasons already dictated, brachial pulse should be regarded as the choice “peripheral” pulse for monitoring in smaller children, as this is more reliable and easier to find and palpate. For a child over the age of 1, systolic blood pressure is estimated using the formula: 90 mmHg + [2 * (age in years)]. Using a pediatric emergency tape, like the Broselow Tape, to identify vital sign abnormalities would be useful in the stressful situation of a mass shooting. Boluses should be completed in 20 mL/kg aliquots and repeated every 30 minutes as needed. Compared to hemorrhage control and circulatory support, airway stabilization in the C-TECC pediatric victim is equally nuanced.

Airway stabilization in the pediatric C-TECC guidelines has specific age-based deviations from those of standard TCCC. Namely, elevating the patient’s shoulders may aid in opening an occluded airway more efficiently when added to conventional practices of clearing the oropharynx, lifting the chin, and applying gentle jaw thrust. For the anatomic reasons discussed, the pediatric airway will benefit from the overall alignment gained in the setting of a larger occiput and thus, become more patent in smaller children with shoulder support. The larger occiput of smaller children should likewise not be overlooked when the victim is ultimately transported off the scene, especially for prolonged periods, as occlusion of the pediatric airway can occur at any time and more easily when compared to adults. Just as stabilizing a native airway, invasive definitive airway placement in pediatric patients of field trauma has its own precautions.

We will continue with Part 2 next week.

Respectfully yours,

Jeffrey Luk, MD

Peds Trauma - June 28, 2021

Good morning,

With this being the final week in our series on pediatric trauma, we will conclude with Part 2 of Tactical Emergency Casualty Care in the pediatric population.

Bag valve mask ventilation, and if needed supraglottic devices, are preferred to intubation if a child can be ventilated adequately. Due to the anatomic differences in both the physical pediatric airway and the limited reserves of the pediatric respiratory system dynamics, any period of time of hypoxia markedly affects both downstream cardiovascular compensatory mechanisms and overall chances of survival in the setting of a significant life-threatening state. Additionally, C-TECC identifies if there is a dire “cannot ventilate, cannot oxygenate” situation in the traumatically injured pediatric patient, the practitioner should pursue needle cricothyrotomy if the patient appears to be pre-pubescent or surgical cricothyrotomy if post-pubescent. Cricothyrotomy, based on relative age, is necessary for the distinct reason that the pediatric airway landmarks and surrounding structures are both immature and difficult to identify. Until the patient is 10-12 years of age, the smaller, more funneled, more anterior airway is crowded and contains conventional landmarks difficult to identify. Needle cricothyrotomy can be performed on any individual if the practitioner is unsure of the patient’s age.

For the pediatric patient having difficulty breathing with impending or active cardiac or respiratory arrest but with a seemingly stable upper airway, needle decompression of the chest should be considered. Smaller losses of respiratory reserve cause larger decompensation proportionally in children than adults, and even a small pneumothorax in some ages can be life-threatening. Previous studies have shown some utility regarding needle decompression in traumatic cardiac arrest; however, several studies call the practice into question as a standard of care. However, in an active-threat event, the consideration of prophylactic bilateral needle decompression would be one for dire circumstances when the practitioner is left with only heroic measures. For this reason, the circumstances may dictate needle decompression as a final life-saving attempt.

The final physiologic component associated with pediatric C-TECC for the practitioner to consider is the body surface area in children. The proportionately larger area, and proportionally smaller ability to generate heat or insulate, likely adds to the already extensively described “trauma triad of death.” With any trauma patient, blood loss contributes to a lack of oxygen-carrying ability; therefore, starting a self-propagating cycle of metabolic lactic acidosis, a decreased myocardial performance, resulting in hypothermia and further fault of the coagulation cascade. In proportionately smaller individuals with a less physiologic reserve and increased susceptibility to the added possibility of elemental exposure, this process occurs more quickly and more chaotically with higher chances of mortality. Therefore, one of the overarching themes for effective treatment of the traumatic pediatric victim in an active threat scenario is not only the familiarization with anatomic and physiologic variations seen in children but also an appreciation of the time restraint put on positive outcomes. Stemming out of the appreciation for the differences in pediatric traumatic response and the associated shorter time to morbidity and mortality is the current emphasis on training the public population in various modalities of life-saving traumatic response.

We hope you found this series of articles on pediatric trauma useful in your care of some of our most vulnerable patients. Please reach out to your medical director if you have any questions!

Respectfully yours,

Jeffrey Luk, MD