Pharmacokinetics of ε-Aminocaproic Acid in Neonates Undergoing Cardiac Surgery with Cardiopulmonary Bypass.

BACKGROUND: Antifibrinolytic medications such as ε-aminocaproic acid (EACA) are used in pediatric heart surgery to decrease surgical bleeding and transfusion. Dosing schemes for neonates are often based on adult regimens, or are simply empiric, in part due to the lack of neonatal pharmacokinetic information. The authors sought to determine the pharmacokinetics of EACA in neonates undergoing cardiac surgery and to devise a dosing regimen for this population. METHODS: Ten neonates undergoing cardiac surgery with cardiopulmonary bypass were given EACA according to standard practice, and blood was drawn at 10 time points to determine drug concentrations. Time-concentration profiles were analyzed using nonlinear mixed effects models. Parameter estimates (standardized to a 70-kg person) were used to develop a dosing regimen intended to maintain a target concentration shown to inhibit fibrinolysis in neonatal plasma (50 mg/l). RESULTS: Pharmacokinetics were described using a two-compartment model plus an additional compartment for the cardiopulmonary bypass pump. First-order elimination was described with a clearance of 5.07 l/h × (WT/70). Simulation showed a dosing regimen with a loading dose of 40 mg/kg and an infusion of 30 mg · kg · h, with a pump prime concentration of 100 mg/l maintained plasma concentrations above 50 mg/l in 90% of neonates during cardiopulmonary bypass surgery. CONCLUSIONS: EACA clearance, expressed using allometry, is reduced in neonates compared with older children and adults. Loading dose and infusion dose are approximately half those required in children and adults.

Cuffed endotracheal tubes in neonates and infants undergoing cardiac surgery are not associated with airway complications.

STUDY OBJECTIVE: To determine the incidence of postoperative airway complications in infants <5kg in weight undergoing cardiac surgery intubated with Microcuff (Kimberley-Clark, Roswell, GA) endotracheal tubes (ETTs). DESIGN: Retrospective review of infants weighing <5.0 kg with congenital heart disease (CHD) presenting for cardiac surgery. SETTING: Single-center, tertiary pediatric cardiac critical care unit at a university hospital. PATIENTS: A total of 208 infants weighing <5 kg underwent cardiac surgery for CHD from 2008 to 2013. INTERVENTION: Intubation with Microcuff (Kimberley-Clark) ETTs. STUDY DESIGN: Retrospective review of infants weighing <5.0 kg with CHD presenting for cardiac surgery to a single-center tertiary care university hospital. MEASUREMENTS: Perioperative data were collected. Primary outcome was development of tracheal stenosis and/or reintubation for stridor. Stridor was defined as mild (≤2 doses of racemic epinephrine), moderate (>2 doses of racemic epinephrine), or severe (requiring reintubation). Secondary outcomes were variables possibly contributing to postextubation stridor. Infants with a tracheostomy, airway anomalies, and death prior to initial extubation were excluded. Logistic regression analysis was performed to evaluate the association between clinical risk factors and the incidence of postextubation stridor. RESULTS: A total of 208 infants weighing <5 kg underwent cardiac surgery for CHD from 2008 to 2013; 12 subjects were excluded for death prior to initial extubation. No infant developed tracheal stenosis. The incidence of any stridor was 20.9% (95% confidence interval, 15.8%-27.1%) with severe stridor in 2 cases (1%). Age at surgery, weight, duration of intubation, dexamethasone use, and ETT size were not significantly associated with postextubation stridor. Presence of a comorbidity was significantly associated with stridor (P=.01). CONCLUSIONS: Microcuff ETTs in infants <5.0 kg in weight undergoing cardiac surgery are associated with a low incidence of severe postextubation stridor. Because cuffed ETTs allow for improved control of ventilation/oxygenation and decreased risk of aspiration, they should be considered for use in this high-risk population. Larger studies are needed to confirm these results.

State-dependent laryngomalacia in sleeping children.

Laryngomalacia is a common congenital laryngeal abnormality. Despite its being widely discussed in the literature, the pathophysiology is not clearly understood. Both anatomic and neuromuscular theories have been suggested to explain laryngomalacia. We report 4 cases of laryngomalacia in which the presenting signs occurred during sleep. Awake flexible nasopharyngolaryngoscopy failed to demonstrate supraglottic structure collapse. Only while the patients were breathing spontaneously under general anesthesia was laryngomalacia noted. A proposed algorithm for diagnosis and treatment is included. These 4 cases of state-dependent laryngomalacia support a neuromuscular cause for laryngomalacia.