Pediatric Anesthesiology 2018 Reviews
CRNA/Allied Heath Symposium
Reviewed by Nate Jones, CRNA
Texas Children’s Hospital, Houston
Challenges in Pediatric Burn Management
Pravin Taneja, MD (St. Christopher’s Hospital for Children, Philadelphia) opened the CRNA/Allied Health Symposium with his presentation on pediatric burn management. Dr. Taneja discussed epidemiology and pathology of burns, assessment of burn injuries, and the anesthetic challenges associated with patients who have burns.
Dr. Taneja reminded us that burns are the leading cause of life-threatening injury worldwide, and are the third leading cause of death in pediatrics. Scald burns predominate in younger children. Different from adults, children require a burn injury of less than 15% total body surface area (TBSA) to trigger a systemic response. Burns evolve in two phases: the burn shock phase (early, first 48 hours) and the hypermetabolic phase (late, after 48 hours, lasting up to 12 months).
The attendees were also informed of the updated classification of burns, which is based on the thickness of, skin layers involved: superficial thickness, superficial partial thickness, deep partial thickness, and full thickness. Various formulas for assessing percentage of burned TBSA include the Rule-of-Nine, the Lund and Browder chart, and the “Palm” method where the size of a patient’s palm represents 1% TBSA.
Management goals of burn injury include maintaining organ and tissue perfusion, controlling infection and the hypermetabolic state, and avoiding inadequate or excessive resuscitation. Dr. Taneja referenced the Bunn et al 2004 Cochrane review of fluid resuscitation in critically ill patients, as well as other research articles on the same topic. He pointed out that there is no evidence that colloid resuscitation reduces the risk of death.
Anesthetic considerations for patients with burn injury include preoperative medication. Dr. Taneja stressed the point that analgesia and anxiolysis must both be addressed as each one can exacerbate the other. Inhalation and intravenous induction methods are both acceptable unless rapid sequence induction is indicated. If inhalation injury is suspected, direct laryngoscopy might be difficult and airway adjuncts (i.e. video laryngoscopy) should be available. Facial burns present a unique challenge for securing the endotracheal tube or laryngeal mask airway.
Patients with burn injuries have an increased metabolic rate and increased minute ventilation. Mechanical ventilation settings should be adjusted accordingly. Anesthesia providers should anticipate large and rapid blood loss when caring for patients undergoing burn wound management. Invasive monitoring should be considered. Hypothermia is the enemy, and operating rooms for patients with burns need to be warm. Succinylcholine is acceptable to use in the first 24 hours, but should be avoided after that due to risk of hyperkalemia.
Dressing changes for patients with burns can be difficult and traumatic. Dr. Taneja advised that combinations of anesthetic drugs could be effective (i.e. propofol/ketamine, propofol/remifentanil). Finally, he talked about non-pharmacologic modalities to assist with dressing changes. Novel approaches include child life therapy, use of video games and virtual reality experiences in cold environments (i.e. walking through snow).
Review of the Current Evidence for the Use of Sugammadex in Pediatrics
James Eiszner, MD (The Children’s Hospital at University of Oklahoma Medical Center, Oklahoma City) opened his presentation with a case scenario about a patient with pyloric stenosis undergoing pyloromyotomy. Ideally, intubating conditions are achieved quickly without the use of succinylcholine and its attendant concerns, and reversal conditions are also quickly achieved due to the short duration of the case. This case scenario elucidated the need for a drug like sugammadex. Dr. Eiszner then polled the room and, by show of hands, most attendees indicated that sugammadex was available in their facility.
Dr. Eiszner reviewed the cyclodextrin structure of sugammadex and creatively analogized it to a donut (a round, sugary object). He reminded us that the function of sugammadex is to bind to steroidal neuromuscular blocking agents, especially rocuronium, and inhibit and reverse their action. Referencing published research, Dr. Eiszner addressed known adverse side effects including hypersensitivity, bradycardia, progesterone binding, and PT/PTT prolongation. Hypersensitivity reactions are rare and respond to typical treatment. Current data do not justify the administration of additional medications to offset bradycardia. Progesterone binding by sugammadex can render oral contraceptives ineffective and affected patients are encouraged to use barrier protection for one week following receipt of sugammadex. Dr. Eiszner reported that PT/PTT prolongation is not associated with clinical bleeding. Special caution should be used in patients with renal failure as there is potential for recurarization. Sugammadex can be dialyzed off, but only with a high flux filter. There is currently no data on sugammadex use in pregnant women.
Dr. Eiszner then reviewed current available evidence of sugammadex in the pediatric population. He reported on a Phase IIIa EU trial by Plaud et al (2009) in Anesthesiology. Their study compared sugammadex with placebo in infants, children, adolescents, and adults. A dose-response relation was demonstrated in all but the infant group and this lack of response was attributed to small sample size. One adverse drug event, bradycardia, was observed.
Dr. Eiszner reviewed prospective, randomized controlled trials (RCT) which showed favorable results with use of sugammadex. Specifically, Grulec et al (2016) in Anesthesia & Analgesia demonstrated that intravenous dexamethasone, given after induction of anesthesia at a dose of 0.5 mg/kg, does not substantially affect the reversal time in patients who received sugammadex following adenoidectomy and/or tonsillectomy. Three RCT by Ghoneim et al, Ozgun et al, and Kara et al compared sugammadex to neostigmine in pediatric populations. In these trials, patients who received sugammadex reached train of four (TOF) ratio of 0.9 more reliably and rapidly, had a shorter time to tracheal extubation, and did not report significant adverse drug events.
Dr. Eiszner also reported on meta-analyses by Liu et al in Nature: Scientific Reports (2017) and Won et al in Medicine (2016). Both studies compared sugammadex with neostigmine and placebo and showed no difference in adverse events. Additionally, sugammadex also reversed rocuronium more rapidly and with less bradycardia than neostigmine. In summary, Dr. Eiszner reported that pediatric evidence for use of sugammadex is promising and that the adverse drug effect and pharmacokinetics of sugammadex are favorable.
Skeletal Dysplasia and Anesthetic Considerations
Sabina DiCindio, DO (Nemours/Alfred I. duPont Hospital for Children, Wilmington) began her presentation with an overview of skeletal dysplasias. Skeletal dysplasias include any generalized abnormality of the skeleton involving the bones and cartilage. To date, more than 450 skeletal dysplasias have been identified. Dr. DiCindio reviewed the classifications of skeletal dysplasias: clinical, radiologic, pathologic, and molecular. She then offered a deeper look at four specific skeletal dysplasias: achondroplasia, osteogenesis imperfecta (OI), Morquio syndrome (MPS IV), and metatropic dysplasia (MD). Anesthetic considerations for each were discussed.
Achondroplasia is present in all genders and races. Intelligence is not affected in patients with achondroplasia. They have a normal life expectancy. Several radiographs of patients with achondroplasia were reviewed. These patients are prone to obstruction to due airway stenosis. Stenosis of the foramen magnum can cause spinal cord compression if the neck is hyperextended, so this must be avoided when positioning patients with achondroplasia.
There are eight types of osteogenesis imperfecta. Types I-IV are more prevalent. Type II is most lethal, whereas Type I is the mildest and most common. Dr. DiCindio showed radiographs and photographs of patients with OI. She then presented results from a study by Sullivan et al (2017) from the Journal of Pediatric Orthopedics. The authors looked at the incidence of fractures from perioperative blood pressure cuff use, tourniquet use, and positioning in patients with OI. The authors concluded that intraoperative use of non-invasive blood pressure cuffs and tourniquets was not associated with iatrogenic fracture. There were no complications related to intra-arterial catheter use. Dr. DiCindio was quick to point out that this study does not give carte blanche when it comes to care for patients with OI. When asked by an audience member what is the preferred method of positioning a patient with OI, Dr. DiCindio strongly recommended parental involvement and expertise. Of note, Dr. DiCindio also pointed out that use of succinylcholine and peripheral nerve stimulators can cause iatrogenic fractures in these patients and should be avoided.
Morquio syndrome is also known as mucopolysaccharidosis IV (MPS IV). Patients with Morquio syndrome are complex. Ninety percent of patients have odontoid dysplasia with atlantoaxial instability. Cervical fusion is common. As a result, mask ventilation and intubation can both be difficult, no matter the modality. Morquio patients can have stenosis of the entire vertebral column. If imaging studies of the spine are not available, providers should assume stenosis is present. Blood pressure should be maintained in the pre-surgical range. It is recommended to obtain baseline neuromonitoring in supine position to assess possible changes with prone positioning. Currently, neuraxial techniques are not recommended in patients with Morquio syndrome.
In patients with metatropic dysplasia, difficult airway is the most common co-morbid condition, especially if their cervical spine has been fused. This was the finding by Theroux et al (2017) in their article from Pediatric Anesthesia. Additionally, Dr. Eiszner (the same James Eiszner who presented earlier in the symposium!) et al (2016) reported in Pediatric Anesthesia that patients with skeletal dysplasia receiving lower extremity nerve blocks consumed minimal opioid and reported no major complications. No nerve injuries were discovered, but further study is necessary to determine whether rates of nerve injury are comparable to those in the general pediatric population. Dr. DiCindio concluded her presentation with the recommendation that care for patients with skeletal dysplasias should be multidisciplinary. She also advised that all patients with skeletal dysplasia, except for those with achondroplasia, should be presumed to have atlanto-occipital instability and cared for accordingly.
Mitochondria Dysfunction and Anesthetic Considerations
Lauren Freedman, CRNA (Johns Hopkins All Children’s Hospital, St. Petersburg) began her lecture with an overview of mitochondrial function, including oxidative phosphorylation. She defined mitochondrial disease and reviewed common symptoms including poor growth, neurological problems, muscle weakness, respiratory problems, and lactic acidosis.
Ms. Freedman presented a case study to help attendees navigate the perioperative course of a patient with a mitochondrial disease. The case involved a 10-year old patient with known mitochondrial disease who presented for replacement of a peripherally inserted central catheter (PICC) line and repair of a gastrocutaneous fistula.
In the preoperative period, it is prudent to avoid prolonged fasting. States of catabolism increase the risk of metabolic decompensation and can increase the risk of perioperative complications. Additionally, preoperative glucose and lactate levels can help inform the anesthetic plan. Ms. Freedman advised that patients with mitochondrial disease are not at increased risk of malignant hyperthermia and the use of total intravenous anesthesia (TIVA) can increase the risk of post-operative complications.
For maintenance of anesthesia, volatile anesthetics are safe for use in patients with mitochondrial disease because those agents do not depend on energy-requiring metabolism. Additional safe medications include dexmedetomidine, opioids, propofol (small dose), ketamine, and benzodiazepines. Propofol affects mitochondrial function via multiple mechanisms and its use should be limited to a single induction dose, if possible. Propofol infusion syndrome, characterized by severe lactic acidosis and rhabdomyolysis, is a risk with TIVA and should be avoided in patients with mitochondrial disease. Neuromuscular blocking drugs have minimal effect on mitochondria but pose the threat of postoperative respiratory compromise and depression.
In the intraoperative period, normothermia should be maintained. Hypothermia depresses mitochondrial function and increased metabolic stress can occur with endogenous warming mechanisms. Ms. Freedman reported that bispectral index (BIS) monitoring is beneficial because patients with mitochondria disease might require less anesthesia, as reported by Morgan et al (2002) in Anesthesiology.
Postoperative concerns were reviewed including respiratory depression, possible prolonged intubation, increased lactic acid levels, temperature derangements, and difficulty with pain control. Finally, Ms. Freedman reviewed laboratory tests for investigating mitochondrial disease.
Anesthesia in the Cardiac Patient for Non-Cardiac Procedures
Elyse Parchmont, CRNA (Texas Children’s Hospital, Houston) opened her presentation with a review of the most common congenital cardiac lesions: septal defects, pulmonary stenosis, tetralogy of Fallot, coarctation of the aorta, atrioventricular septal defects, and transposition of the great arteries. High risk lesions include single ventricle physiology, left ventricular outflow tract obstruction (LVOTO), cardiomyopathy, and pulmonary hypertension.
Ms. Parchmont discussed preoperative preparation for cardiac patients who present for non-cardiac procedures. She reminded attendees of the importance of multidisciplinary planning with consult services, cardiology, surgery, anesthesia, and family. It is important to weigh the risk versus benefit of a procedure. The anesthesia provider and surgeon should together determine the optimal operating environment, be it an outpatient operating room or a cardiovascular operating room. Additional considerations include possibility of anesthetic bundling and postoperative ICU admission.
For shunted patients and those with LVOTO, hypotension with induction of anesthesia is concerning. It is wise to minimize fasting in these patients and allow liberal oral clear liquids up until two hours prior to procedure. Intravenous fluids can also be initiated when the patient arrives for the procedure. The discontinuation and restarting of anticoagulation drugs should be discussed with the patient’s cardiologist and consulting surgeon.
Ms. Parchmont reviewed pacemakers and defibrillators and reminded of the importance of device interrogation prior to a procedure. Temporary pacing equipment should be available and anesthesia personnel should be familiar with its use in case of emergency. Magnets should only be used in an emergency and do not replace the need for device interrogation. When a patient with a left ventricular assist device (LVAD) presents for anesthesia, a perfusionist or LVAD-trained nurse should be present. Bacterial endocarditis prophylaxis is required for patients with an LVAD. Due to anticoagulation therapy, patients with an LVAD tend to have more procedural bleeding than is typical.
Ms. Parchmont discussed high-risk cardiac patients next. Single ventricle palliation was reviewed and she advised that the Glenn stage is the most stable stage for elective non-cardiac procedures, though instability should be expected at all stages. Lower than normal oxygen saturations (75-85%) and diastolic blood pressures are expected in shunt-dependent patients with a single ventricle. Treatment of pulmonary hypertension was reviewed, as well as anesthetic considerations for severe aortic stenosis, Williams Syndrome, and hypertrophic cardiomyopathy.
Finally, Ms. Parchmont reviewed complex surgical situations including laparoscopic surgery, direct laryngoscopy and bronchoscopy, spinal surgery, and non-OR anesthesia such as magnetic resonance imaging (MRI) and computed tomography (CT). For all cardiac patients, the choice of anesthetic depends on the surgery, duration, the patient’s anatomy, and the patient’s physiologic reserve. Patients with congenital heart disease do not tolerate fast, deep inductions, and it is prudent to proceed slowly. Premedication is also beneficial for cardiac patients who have likely endured multiple procedures and may have trauma as a result. Postoperative disposition of the patient (postoperative care unit v. ICU) depends on severity of the surgery as well as intraoperative course. Ms. Parchmont advised that single ventricle pre-Glenn patients should recover in ICU, and all patients with pulmonary hypertension should be admitted for observation.
