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When pediatric patients require mechanical ventilation in the emergency department, the emergency clinician should be prepared to select initial ventilator settings and respond to an intubated patient’s dynamic physiologic needs to ensure ongoing oxygenation, ventilation, and hemodynamic stability. Pressure-targeted ventilation is generally recommended in pediatric patients, with initial ventilator settings varying depending on age and the etiology of respiratory failure. This issue reviews indications for mechanical ventilation and offers recommendations for ventilator settings and dosing of analgesics, sedatives, and neuromuscular blockers, with a focus on patient populations in whom the approach to mechanical ventilation may be different.
A 2-month-old boy presents to your community ED with intermittent apnea, cough, and congestion. He was born at 34 weeks’ gestation, and his current weight is 4.5 kg. His parents report the infant's 3-year-old sister was recently diagnosed with respiratory syncytial virus. The baby has increased work of breathing, diffuse coarse breath sounds, and wheezing. Despite suctioning and a trial of noninvasive positive pressure ventilation, he continues to have apneic episodes and is ultimately intubated. The respiratory therapist asks you what ventilator settings you would like to use, but you hesitate. What is the ideal mode of ventilation, and what should the initial settings be? How are you going to keep the baby comfortable while intubated?
An 8-year-old girl presents from home with increasing shortness of breath. She has a history of poorly controlled asthma and has had multiple prior admissions to the PICU for status asthmaticus. She has an upper respiratory tract infection that began 2 days ago, and she has been receiving albuterol every 2 hours via her inhaler for the past 12 hours. She speaks in 1- to 2-word sentences and uses respiratory accessory muscles. On auscultation of her lungs, she has poor air entry and minimal end-expiratory wheezing. Upon arrival to the ED, her vital signs are: heart rate, 160 beats/min; respiratory rate, 50 breaths/min; blood pressure, 110/75 mm Hg; pulse oximetry, 85%. She is given IV corticosteroids, continuous bronchodilators, IV magnesium, and beta agonists. She is started on noninvasive positive pressure ventilation. Within the next hour, she is poorly responsive and her respiratory effort declines. She is intubated and started on mechanical ventilation. While you continue to treat the patient’s status asthmaticus, you recall that young patients with severe asthma can be difficult to manage on a ventilator, and you begin to doubt your initial plan. You wonder whether there is anything that can be done to avoid the difficulties of mechanical ventilation in this patient and what to do if you run into them. What initial ventilator settings should you use for this patient? What are the next steps in assessment if she develops high peak pressures while in a volume-controlled mode of ventilation? What are the next steps in treatment if she develops severe auto–positive end-expiratory pressure and associated hypotension?
A 15-year-old boy is brought to the ED after being found at the bottom of a neighbor’s pool in an apparent drowning event. Bystander CPR was initiated. On EMS arrival, the patient was awake and alert. During transport, he was in moderate respiratory distress with an oxygen saturation of 85% on a nonrebreather mask. On arrival to the ED, he is intubated for continued respiratory failure and hypoxia. The patient's oxygen saturation improved after intubation. However, prior to transport to the PICU, the patient again desaturated to 86%. Using the DOPES mnemonic, how should you troubleshoot this problem? What additional complications may result from using a high positive end-expiratory pressure?
A 7-year-old girl with a history of epilepsy and developmental delay presents with increased seizure activity in the setting of several days of fever and congestion. On arrival, she is noted to have ongoing generalized tonic-clonic activity without a return to her baseline mental status. She is given lorazepam, levetiracetam, and fosphenytoin for ongoing seizures, after which she is noted to be bradypneic with desaturation to 87% on room air. You make the decision to intubate her for airway protection, given the ongoing need for antiepileptic medications. What initial ventilator settings should you use for this patient? What sedation and analgesia should you choose to start with?
Intubation of pediatric patients in the emergency department (ED) is a high-risk procedure that occurs infrequently.1-3 Management challenges do not end once the patient is intubated, however; the emergency clinician must select initial ventilator settings and respond to the patient’s dynamic physiologic needs to ensure ongoing oxygenation, ventilation, and hemodynamic stability.4 Recent literature indicates that emergency clinicians who are caring for mechanically ventilated adult patients frequently choose ventilator modes and settings that are not consistent with critical care practice and guidelines.5-8
Pediatric patients sometimes require ongoing critical care (including ventilator management) in the ED. Children who present to smaller community hospitals and are intubated need active ventilator management while awaiting transfer to tertiary centers capable of pediatric critical care. It is paramount that emergency clinicians effectively manage mechanical ventilation settings and related complications for pediatric patients. This issue of Pediatric Emergency Medicine Practice reviews pearls and pitfalls related to management of pediatric mechanical ventilation. Preterm neonatal ventilation requires additional considerations and expertise and is out of scope of this review.
A literature search of the PubMed database was conducted using the keywords mechanical ventilation, pediatrics, and emergency medicine. In total, 74 articles from 1950 to the present were reviewed. The vast majority of articles related to pediatric mechanical ventilation come from the fields of critical care (neonatal and pediatric) and anesthesia. There is a paucity of data and few randomized controlled trials from which to draw best-practice guidelines. A 2011 systematic review and meta-analysis on pediatric mechanical ventilation included only 5 randomized controlled trials.9 More recently, 2 reports reviewed current pediatric mechanical ventilation recommendations, but were based on consensus from expert panels.10,11 Both note the remarkable absence of well-designed studies to guide approaches to pediatric mechanical ventilation and, as such, are somewhat limited in their conclusions and definite recommendations.10,11
The goal of mechanical ventilation is to restore physiologic gas exchange, reduce work of breathing, and protect the airway in patients who are unable to do so. The conditions that may contribute to respiratory failure and indicate the need for mechanical ventilation in pediatric patients are similar to those in adults. (See Table 1.) Generally, indications for mechanical ventilation can be separated into 3 categories: (1) inadequate oxygenation, (2) inadequate ventilation, or (3) need for airway protection. (See Table 2.) It is important to assess and understand the clinical indications, as these will help guide choices related to mode of ventilation and ventilator settings.
Neonates and infants have a higher frequency of respiratory failure compared to older children,12 and their unique physiology warrants special consideration in the setting of mechanical ventilation. Infants are especially prone to atelectasis for several reasons; they have smaller intrathoracic airway caliber with limited cartilaginous support, as well as fewer alveoli.13 Pediatric patients have higher resistance due to narrower airways, as well as high chest-wall compliance.14 A more pliable chest wall results in lower functional residual capacity.14 It is important to note that tidal volumes measured by the ventilator are not especially accurate in infants and small children.15,16
4. “My patient's initial blood gas results looked pretty good, so I didn’t get any more labs on him.”
Patients with respiratory failure have dynamic physiology. It is paramount to regularly reassess patient status, blood gas values, and ventilator settings, especially in the first few hours after intubation and initiation of mechanical ventilation.
6. “I wasn't sure why the baby was desaturating, so I increased the FiO2 to try to fix it.”
Use a systematic approach to patients with hypoxia. Consider tube dislodgement, airway obstruction, pneumothorax, equipment failure, stacking, or some combination of these factors. FiO2 and/or PEEP may need to be increased, but other reasons for hypoxia should be considered.
8. “My patient with asthma was hypercapnic and his pH was 7.25. I decided to increase his respiratory rate to optimize the numbers.”
Hypercapnia should be tolerated in order to achieve safe and clinically appropriate tidal volumes, peak pressures, and plateau pressures. Increasing ventilator settings in order to achieve normal CO2 and normal pH may be ultimately deleterious and a source for ventilator-induced lung injury.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study is included in bold type following the reference, where available. In addition, the most informative references cited in this paper, as determined by the author, are highlighted.