Nischal K. Gautam

Successful intra-arterial thrombolytic therapy for a right middle cerebral artery stroke in a 2-year-old supported by a ventricular assist device

Embolic stroke is a common complication in patients on ventricular assist devices in both adults and children. The reported incidence of strokes in children supported by VAD’s varies from 7 to 38%. The rapid increase in recent years in the availability of both adult and pediatric VADs will likely add to the overall prevalence of strokes in patients being bridged to heart transplant. Strokes in this population can be lethal as they frequently necessitate withdrawal of the extracorporeal device support and withdrawal from the organ transplant waiting list. We present a case of a fully anti‐coagulated 29‐month‐old supported on a Berlin EXCOR LVAD (Berlin, Germany) with embolic stroke which was treated successfully with direct thrombolysis with recombinant tissue plasminogen activator. This is the first report which uses intra‐arterial thrombolytics while on a ventricular assist device in a pediatric patient.

Impact of protamine dose on activated clotting time and thromboelastography in infants and small children undergoing cardiopulmonary bypass.

To study the effect of two protamine‐dosing strategies on activated clotting time (ACT) and thromboelastography (TEG).

Transesophageal doppler measurement of renal arterial blood flow velocities and Indices in children

BACKGROUND: Doppler-derived renal blood flow indices have been used to assess renal pathologies. However, transesophageal ultrasonography (TEE) has not been previously used to assess these renal variables in pediatric patients. In this study, we (a) assessed whether TEE allows adequate visualization of the renal parenchyma and renal artery, and (b) evaluated the concordance of TEE Doppler-derived renal blood flow measurements/indices compared with a standard transabdominal renal ultrasound (TAU) in children. METHODS: This prospective cohort study enrolled 28 healthy children between the ages of 1 and 17 years without known renal dysfunction who were undergoing atrial septal defect device closure in the cardiac catheterization laboratory. TEE was used to obtain Doppler renal artery blood velocities (peak systolic velocity, end-diastolic velocity, mean diastolic velocity, resistive index, and pulsatility index), and these values were compared with measurements obtained by TAU. Concordance correlation coefficient (CCC) was used to determine clinically significant agreement between the 2 methods. The Bland-Altman plots were used to determine whether these 2 methods agree sufficiently to be used interchangeably. Statistical significance was accepted at P ⩽ 0.05. RESULTS: Obtaining 2-dimensional images of kidney parenchyma and Doppler-derived measurements using TEE in children is feasible. There was statistically significant agreement between the 2 methods for all measurements. The CCC between the 2 imaging techniques was 0.91 for the pulsatility index and 0.66 for the resistive index. These coefficients were sensitive to outliers. When the highest and lowest data points were removed from the analysis, the CCC between the 2 imaging techniques was 0.62 for the pulsatility index and 0.50 for the resistive index. The 95% confidence interval (CI) for pulsatility index was 0.35 to 0.98 and for resistive index was 0.21 to 0.89. The Bland-Altman plots indicate good agreement between the 2 methods; for the pulsatility index, the limits of agreement were −0.80 to 0.53. The correlation of the size of the measurement and the mean difference in methods (−0.14; 95% CI = −0.28, 0.01) was not statistically significant (r = 0.31, P = 0.17). For the resistive index, the limits of agreement were −0.22 to 0.12. The correlation of the size of the measurement and the mean difference in methods (−0.05; 95% CI = −0.09, −0.01) was not statistically significant (r = 0.10, P = 0.65). CONCLUSION: This study confirms the feasibility of obtaining 2-dimensional images of kidney parenchyma and Doppler-derived measurements using TEE in children. Angle-independent TEE Doppler-derived indices show significant concordance with those derived by TAU. Further studies are required to assess whether this correlation holds true in the presence of renal pathology. This technique has the potential to help modulate intraoperative interventions based on their impact on renal variables and may prove helpful in the perioperative period for children at risk of acute kidney injury.

Preincision Initiation of Dexmedetomidine Maximally Reduces the Risk of Junctional Ectopic Tachycardia in Children Undergoing Ventricular Septal Defect Repairs

OBJECTIVE To evaluate whether initiation of dexmedetomidine (DEX) infusion before surgical incision and cardiopulmonary bypass (CPB) versus initiation after CPB had an impact on the incidence of junctional ectopic tachycardia (JET). DESIGN Retrospective cohort study. SETTING Single tertiary-care cardiac center. PARTICIPANTS Children undergoing cardiopulmonary bypass for repair of congenital heart disease involving ventricular septal defects between January 2010 and February 2013. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS One hundred thirty-four patients undergoing ventricular septal defect closure were included in the final analysis. Of the 99 patients (74%) exposed to DEX, intraoperative initiation was performed in 73 (pre-CPB, n = 39 patients [29%]; intraoperative post-CPB initiation, n = 34 patients [25%]), and postoperative initiation was performed on arrival to the intensive care unit (ICU) in 26 patients (19%). In 71 of the 73 patients, infusions that were initiated intraoperatively were continued in the postoperative period for up to the first 12 hours. Postoperative JET was observed in 22 of the 134 patients (15%). Of the 99 patients exposed to DEX in the perioperative period, JET was observed in 8 patients (11%). Of the 35 patients not exposed to any DEX, JET was observed in 12 patients (34%). Analysis was performed using DEX exposure and timing as predictor variables. Multivariable analysis modeled with DEX exposure as a predictor variable showed that when initiated preincision and continued through the postoperative period, DEX was associated with significant reduction in postoperative JET (odds ratio [OR] 0.09, 95% confidence interval [CI] 0.02-0.37, p = 0.002). Exposure to DEX in the postoperative period alone did not result in suppression of JET (OR 0.5, 95% CI 0.11-2.17, p = 0.366). When modeled by using timing of DEX initiation as the predictive variable, preincision initiation of DEX infusion resulted in significantly greater suppression of JET (OR 0.04, 95% CI 0.002-0.28, p = 0.006) compared with initiation intraoperatively after CPB (OR 0.16, 95% CI 0.03-0.71, p = 0.024) or on arrival to the ICU (OR 0.504, CI 0.105-2.171, p = 0.365). Use of DEX exclusively in the postoperative period did not demonstrate any significant benefit in reducing JET (OR 0.506, 95% CI 0.106-2.17, p = 0.366). CONCLUSIONS Preincision initiation of DEX and its continued use during the immediate postoperative period are significantly associated with reduced risk of JET after congenital heart surgeries involving repair of ventricular septal defect.

Performance of functional fibrinogen thromboelastography in children undergoing congenital heart surgery

Functional Fibrinogen assay of the Thromboelastography (FFTEG), a whole blood viscoelastic hemostatic assay, has been used to estimate fibrinogen levels in adult patients undergoing major surgery but its performance in pediatric patients undergoing cardiac surgery requires evaluation. In this study, we evaluate the correlation between FFTEG parameters and standard laboratory tests for fibrinogen and platelet counts before and after cardiopulmonary bypass in children undergoing repair for congenital heart disease.

Introduction of color-flow injection test to confirm intravascular location of peripherally placed intravenous catheters

The incidence of infiltration and extravasation when using peripheral intravenous catheters is high in pediatric patients. Due to the lack of a gold standard test to confirm intravascular location of a peripherally placed intravenous catheter, we introduce a novel method, the color‐flow injection test to assess the intravascular location of these catheters. For the color‐flow injection test, 1 mL of normal saline was injected within 2 seconds in the distal intravenous catheter and changes in color‐flow via ultrasonography were observed at the proximal draining veins. The primary objective of the study was to demonstrate feasibility of the color‐flow injection test.

Impact of isoproterenol infusion on BIS and metabolic values in pediatric patients undergoing electrophysiology studies

STUDY OBJECTIVE To study changes in BIS values and metabolic parameters during an infusion of isoproterenol in pediatric patients. DESIGN Retrospective study approved By Committee For The Protection Of Human Subjects at University Of Texas Medical School at Houston. SETTING University-affiliated childrens hospital. MEASUREMENTS The records of pediatric patients undergoing general anesthesia for electrophysiology procedures were analyzed. Electronic data collected included Bispectral Index (BIS) values, anesthetics (eg, opioids, expired concentration of inhaled anesthetics, muscle relaxants), hemodynamic values (ie, heart rate, invasive blood pressure), respiratory parameters [ie, tidal volume, respiratory rate, end-tidal CO2 (ETCO2)], and routine arterial blood gases. These parameters were analyzed 10 minutes prior to the start of the isoproterenol infusion (T-pre) and 10 minutes after isoproterenol had reduced the cardiac cycle length by 20% (T-infusion). MAIN RESULTS Of the 29 records that were screened, 22 met the above criteria (mean age 13 ± 5 yrs). BIS values increased by an average of 8 (33 ± 8 to 41 ± 10; P < 0.001) during the isoproterenol infusion. Statistically significant increases in ETCO2 (median 33 - 36 mmHg; P = 0.01), PaCO2 (35 - 38 mmHg; P = 0.002), and lactate (1.1 -1.5 mg/dL; P < 0.001) occurred with infusion of isoproterenol. Patients undergoing controlled mechanical ventilation showed an increase in ETCO2 (mean 34 ± 6 mmHg to 37 ± 5 mmHg; P = 0.001) whereas those breathing spontaneously had an increase in minute ventilation (average increase 111 ± 30 mL/kg). CONCLUSIONS Isoproterenol increases metabolic, respiratory, and BIS values in pediatric patients during general anesthesia. We recommend the use of BIS, close monitoring of ETCO2, and careful titration of anesthetics during isoproterenol infusion, especially when lighter planes of general anesthesia are requested for pediatric electrophysiologic procedures.

Is the “triple Low” Association with Death Statistically Valid or Reflective of Clinical Practice?

To the Editor: We are intrigued to read Willingham et al.’s1 strongly worded retrospective, observational conclusion from three previously reported trials that the concurrence of intraoperative hypotension, low minimum alveolar concentration, and low bispectral index (BIS), the so-called “triple low,” was independently associated with postoperative death. We have several observations noting that several of the current authors were original contributors to the referenced studies.