spa-aap reviews
Saturday Session IV: Ask the Experts Panel
Reviewed by Agnes Hunyady, MD
Seattle Children’s Hospital
In her talk titled “Bleeding Management in the Patient Undergoing Craniofacial Reconstruction”, Susan M. Goobie, MD, FRCPC (Boston Children’s Hospital) discussed the current indications and hazards of blood transfusion in pediatrics and highlighted blood conservation methods in pediatric patients. Albeit the context was craniofacial reconstruction, a procedure that has the second highest transfusion rate among pediatric non-cardiac procedures, Dr. Goobie’s comprehensive review provided applicable data for the perioperative management of children undergoing other high-volume blood loss procedures.
Most of us are familiar with the deleterious effects of hypovolemia on tissue perfusion and O2 delivery and the fact that hypovolemia, blood loss and hyperkalemia related to blood transfusion became the most common cause of intraoperative cardiac arrest in children undergoing non-cardiac surgery. We are, however, less aware of how commonly over-transfusion happens in children. Incorrect blood component transfused and inappropriate or unnecessary transfusion are responsible for 80% of reported cases of serious hazards of transfusion (SHOT). SHOT effects infants in larger proportion than older children, and it results in an overall death rate of two for every 100,000 transfusions.
Dr. Goobie gave a great overview of the most common major morbidities associated with transfusion. Transfusion-Associated Circulatory Overload (TACO) together with Transfusion Related Acute Lung Injury (TRALI) contribute to the high incidence of Respiratory Dysfunction Associated with Transfusion (RDAT), which was observed in 43% among transfused pediatric ICU patients in a study. TACO is becoming more common than TRALI, although TRALI remains underestimated and underreported. The similar symptomatology can sometimes make it difficult to differentiate between them. TRALI is the leading cause of transfusion-related death in the USA. Its incidence increases with the increase of blood volume transfused. The incidence is as high as 7% in transfused critically ill patients. Transfusion related immune modulation (TRIM) refers to the transient depression of the immune system following blood product transfusion. It is potentially the most harmful, but an incompletely understood transfusion-related phenomenon. It encompasses effects like cancer recurrence, postoperative infection, virus activation. The rate of transfusion transmitted infections (TTI) related to PRBCs is very low in the US, but concerns remain worldwide about the inconsistency of systematic screening for Hepatitis B and C and HIV viruses, as well as about the role of emerging pathogens (Zika, West Nile virus, babesiosis, etc.)
Allogenic blood transfusion is associated with an increased incidence of 30-day in-hospital mortality and postoperative complications in children undergoing non-cardiac surgery. The larger the volume transfused, the larger the risk. For example, transfusion volumes larger than 60 ml/kg were associated with a 93% clinically relevant postoperative events in open craniosynostosis repair (Goobie et al. Anesthesiology 2015.) Whether the association is related to the reason to transfuse (anemia) the cause of bleeding or the blood product transfused, remains to be studied in prospective trials.
Regardless of whether transfusion is a risk factor or merely a risk marker, blood transfusion is one of the most commonly overused health care intervention worldwide, and wiser blood management strategies, including promotion of the availability of transfusion alternatives, were identified as one of the most important issues by the WHO. The ASA Task Force on Blood Management calls for restrictive transfusion strategy, multimodal protocols, use of antifibrinolytics, institution of massive transfusion protocols and cell salvage. It provides, however, no specific recommendation for pediatrics, and the feasibility, applicability of some of these recommendations in pediatric remains problematic and the effects of such strategies are understudied in this population.
Evidence exists, however, on the importance of correcting preoperative anemia. Postoperative mortality in neonates and children with preoperative anemia is significantly higher than in those without. Therefore, early recognition, prevention and treatment of anemia – postponement of elective surgery, minimalization of blood draws, iron supplementation, use of recombinant human erythropoietin - should be strived for to improve outcome and survival.
Intraoperatively, judicious fluid management, i.e. avoidance of hypervolemia leading to hemodilution induced anemia and coagulopathy, is important. The effects of liberal versus restrictive transfusion strategies are derived from studies conducted in the critical care setting. Recommendation on the hemoglobin level at which transfusion should be considered depends on the age of the child and the comorbidities. In the first 24 hours of life and for neonates requiring invasive ventilation, the threshold should be 12 g/dl. For neonates without O2 requirement and in pediatric patients it can be decreased to 7-8 g/dl. Certain special circumstances, like ECMO treatment, presence of cyanotic congenital heart disease, early stages of sepsis call for higher thresholds – 12-15, 10-12 and 10 g/dl, respectively. In severe pediatric bleeding a threshold of 8 g/dl maybe a safe choice.
Dr. Goobie pointed out that blood conservation should be a team effort, and that meticulous surgical hemostasis is part of blood conservation. New surgical techniques, like endoscopic as opposed to open craniosynostosis repair and surgical planning with 3D models have been shown to reduce blood loss. Application of cell salvage devices remains problematic in children weighing less than 10 kg. Antifibrinolytics have been shown to decrease blood loss, volume of blood transfused and transfusion complications in children undergoing noncardiac surgery, without an increase in adverse events related to drug use. The evidence is the strongest for tranexamic acid, which also reduces FFP transfusion in craniosynostosis surgery. A high dose regime, however, might increase the risk of seizure in children with renal insufficiency and neurological comorbidity. Based on her pharmacokinetic studies, Dr. Goobie recommends a 10 mg/kg loading dose, followed by a 5 mg/kg/h infusion.
Challenging Craniofacial Syndromes
Franklyn P. Cladis, MD, FAAP (The Children’s Hospital of Pittsburgh) gave an overview of challenging craniofacial syndromes, describing their classification, discussing the perioperative concerns related to them and providing guidance for anesthetic management.
The Committee on Nomenclature and Classification of Craniofacial Anomalies grouped craniofacial syndromes according to their anatomical features. Four groups have been established:
- Synostosis
- Hypoplasia (Atrophy)
- Clefts
- Hyperplasia (Neoplasia)
The first three groups were discussed in detail in Dr Cladis’ talk.
Abnormal closure of one or more cranial sutures results in abnormal head shape and brain development, increased ICP and altered vision. Craniosynostoses can be simple or complex (syndromic). The latter ones include six acrocephaly-syndactyly syndromes (Apert, Pfeiffer, Saethre-Chotzen, Carpenter, Antley-Bixler and Meunke) and one without limb deformities: Crouzon syndrome. A common feature of syndromic synostoses is midface hypoplasia resulting in obstructive sleep apnea. In addition, there can be choanal stenosis/atresia, tracheal anomalies and cervical spine abnormalities to further complicate airway management. Most common surgical interventions are synostosis repairs in this group, and midface advancements in the syndromic subgroup as well as orthopedic procedures. Intraoperative challenges include airway issues especially difficult mask ventilation and maintaining airway patency on emergence, the high-volume blood loss, sometimes increased ICP and positioning.
Hypoplasias include Robin sequence, Goldenhar syndrome and Romberg’s disease. Robin sequence refers to the triad of micrognathia, glossoptosis and airway obstruction (cleft palate). It can be isolated or syndromic. Common syndromes associated with Robin sequence include Stickler, Treacher Collins, fetal alcohol and velocardiofacial syndromes. A not so well known fact is that there is a high incidence of associated cervical spine anomalies with these syndromes. Initial evaluation of patients with syndromic Robin sequence, therefore, should include not only head and neck CT, bedside endoscopy, polysomnography and barium swallow, but also cervical spine imaging.
Airway obstruction can vary from mild to severe and can be accompanied by central apnea and neurological comorbidity. Thus, management varies between conservative treatment (positioning) and surgical interventions ranging from tongue-lip adhesion and mandibular distraction osteogenesis to tracheostomy followed by distraction osteogenesis, and occasionally cervical spine stabilization. Anesthesia concerns are mainly related to airway management, as both mask ventilation and intubation can be challenging. Alternative intubation techniques – awake LMA placement, intubation through and LMA (AirQ) as a conduit, use of indirect laryngoscopic devices, fiberoptic intubation – should be considered. Goldenhar syndrome is characterized by hemifacial macrosomia, epibulbar dermoid and cervical anomalies. Surgical interventions commonly include distraction osteogenesis, maxillary and mandibular osteotomies, ear and various soft tissue reconstruction. Airway management can be complicated by not only micrognathia but also microstomia and cervical spine anomalies.
Craniofacial clefts have been classified by Tessier, based on anatomical position. They happen along one of 15 lines in midline, paramedian, orbital or lateral position, and affect boney structures, soft tissues or both. Clefting can affect one Tessier line (e.g. simple cleft lip or palate), can be part of a syndrome (e.g. velocardiofacial, Stickler syndromes) or can affect several Tessier lines resulting in complex anomalies. Example for the latter is Treacher Collins syndrome (zygotemporoauromandibular dysplasia), where Tessier six, seven and eight clefts result in poor infraorbital ridges, absent zygomas, small midface, hearing deficit, hypoplastic and abnormal mandible. It has an autosomal dominant inheritance, with often increased expression in subsequent generations. Patients usually undergo numerous reconstructive surgeries, requiring repeated anesthetics. Intubation is usually very challenging.
In summary, Dr. Cladis emphasized the presence of multilevel airway obstruction in children with craniofacial anomalies and underlined the importance of careful postoperative planning.
