Frequency domain analysis of photoplethysmographic and arterial pressure waveforms for assessing hemodynamics in children with congenital heart surgery.

BACKGROUND: Time-domain parameters are less reliable in children due to increased arterial and chest wall compliance. We assessed the ability of indices derived from frequency analysis of photoplethysmography (PPG) and arterial blood pressure (ABP) waveforms to predict the hemodynamic state in children undergoing congenital heart surgery. METHODS: We analyzed waveforms after cardiopulmonary bypass period in 76 children who underwent total repair of congenital heart disease. Amplitude density of baseline and amplitude modulation in PPG and ABP by respiratory frequency were obtained using fast Fourier transform analysis and normalized by cardiac pulse height (representing respiratory modulations in venous blood [PPG-DC%] and in amplitude [PPG-AC%] at respiratory frequency). The ratio of amplitude density of PPG at the cardiac frequency (CF) to ABP-CF was used to assess vascular compliance. We assessed volume replacement (ml/kg) and vasoactive inotropic score (VIS). RESULTS: Children requiring volume replacement > 10 ml/kg (15.8%) showed higher PPG-DC% than those not requiring it (median: 52.4%, 95% CI [24.8, 295.1] vs. 36.7% [10.7, 125.7], P = 0.017). In addition, children with a VIS > 7 (22.4%) showed higher PPG-CF/ABP-CF (3.6 [0.91, 10.8] vs. 1.2 [0.27, 5.5], P = 0.008). On receiver operating characteristic curve analysis, PPG-DC% predicted a higher fluid requirement (area under the curve: 0.71, 95% CI [0.604, 0.816], P = 0.009), while PPG-CF/ABP-CF predicted a higher VIS (0.714, [0.599, 0.812], P = 0.004). CONCLUSIONS: Frequency domain analysis of PPG and ABP may assess hemodynamic status requiring fluid or vasoactive inotropic therapy after congenital heart surgery.

Preoperative low muscle mass and early postoperative outcomes in children undergoing living donor liver transplantation: A retrospective study.

Low skeletal muscle mass may develop in children with end-stage liver disease, affecting postoperative outcomes. We retrospectively investigated whether preoperative low muscle mass was associated with early postoperative outcomes in pediatric patients undergoing living donor liver transplantation (LDLT). Electronic medical records of children (age below 12 y) who underwent LDLT between February 1, 2007, and January 31, 2018, were reviewed. The cross-sectional areas of psoas, quadratus lumborum, and erector spinae muscles at the level of fourth-fifth lumbar intervertebral disks were measured using abdominal CT images, divided by the square of the height and were added to obtain the total skeletal muscle index (TSMI). The patients were divided into two groups according to the median TSMI in the second quintile (1859.1 mm 2 /m 2 ). Complications in the early postoperative period (within 30 d after surgery) classified as Clavien-Dindo grade 3 or higher were considered major complications. Logistic regression analyses were performed to determine the association between preoperative low muscle mass and early postoperative outcomes. In the study population of 123 patients (median age, 14 mo; range, 8-38 mo) who underwent LDLT, 29% and 71% were classified in the low (mean TSMI, 1642.5 ± 187.0 mm 2 /m 2 ) and high (mean TSMI 2188.1 ± 273.5 mm 2 /m 2 ) muscle mass groups, respectively. The rates of major complications, mechanical ventilation >96 hours, intensive care unit stay >14 days, hospital stay >30 days, and in-hospital mortality were not significantly different between the 2 groups. Additionally, adverse outcomes according to pediatric end-stage liver disease scores and sex were not significantly different between the 2 groups. In conclusion, preoperative low muscle mass defined by TSMI was not associated with early postoperative outcomes in pediatric patients undergoing LDLT.

Association Between Preoperative Sarcopenia and Early Postoperative Outcomes in Pediatric Patients Undergoing Total Correction of Tetralogy of Fallot: A Retrospective Cohort Study.

OBJECTIVES: To identify the association between preoperative low muscle mass and early postoperative outcomes in pediatric patients undergoing total correction of tetralogy of Fallot (TOF). DESIGN: A retrospective cohort study. SETTING: A single university hospital in Seoul, South Korea. PARTICIPANTS: Pediatric patients (≤3 years) who underwent total correction of TOF between May 2008 and February 2018. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Cross-sectional areas of the pectoralis and erector spinae muscles were measured using preoperative chest computed tomography (CT) scans, and adjusted to body surface area to define muscle mass index. The patients were divided into sarcopenia, presarcopenia, and no sarcopenia groups based on cutoff values determined using the mean and SD of the muscle mass index in the third z-weight quintile. Of a total of 330 patients included in the final analysis, 13 were associated with the sarcopenia group, 57 in the presarcopenia group, and 260 in the no sarcopenia group. The sarcopenia group exhibited a higher incidence of major adverse events than the presarcopenia and no sarcopenia groups, respectively (38% v 25% v 18%; p = 0.033). Logistic regression analyses revealed that only younger age at the time of surgery was significantly associated with major adverse events (odds ratio 0.82; 95% CI 0.72-0.94, p = 0.003). CONCLUSIONS: The incidence of sarcopenia, as assessed by preoperative chest CT, was low in pediatric patients undergoing total correction of TOF, and preoperative sarcopenia did not predict early postoperative major adverse events.

Excess out-of-hospital cardiac arrests due to ambient temperatures in South Korea from 2008 to 2018.

Out-of-hospital cardiac arrest (OHCA) is a notable public health issue with negative outcomes, such as high mortality and aftereffects. Additionally, the adverse effects of extreme temperatures on health have become more important under climate change; however, few studies have investigated the relationship between temperature and OHCA. In this study, we examined the association between temperature and OHCA and its underlying risk factors. We conducted a two-stage time-series analysis using a Poisson regression model with a distributed lag non-linear model (DLNM) and meta-analysis, based on a nationwide dataset from South Korea (2008-2018). We found that 17.4% of excess OHCA was attributed to cold, while 0.9% was attributed to heat. Based on central estimates, excess OHCA attributed to cold were more prominent in the population with hypertension comorbidity (31.0%) than the populations with diabetes (24.3%) and heart disease (17.4%). Excess OHCA attributed to heat were larger in the populations with diabetes (2.7%) and heart disease comorbidity (2.7%) than the population with hypertension (1.2%) based on central estimates. Furthermore, the time-varying excess OHCA attributed to cold have decreased over time, and although those of heat did not show a certain pattern during the study period, there was a weak increasing tendency since 2011. In conclusion, we found that OHCAs were associated with temperature, and cold temperatures showed a greater impact than that of hot temperatures. The effects of cold and hot temperatures on OHCA were more evident in the populations with hypertension, diabetes, and heart diseases, compared to the general population. In addition, the impacts of heat on OHCA increased in recent years, while those of cold temperatures decreased. Our results provide scientific evidence for policymakers to mitigate the OHCA burden attributed to temperature.

A look into hemostatic characteristics during pediatric liver transplantation using the thromboelastometry (ROTEM® ) test.

There is a paucity of evidence about the coagulation profile regarding the complexity of children undergoing liver transplantation (LT). This study aimed to investigate intraoperative hemostatic changes during pediatric LT according to the etiology for LT and examine the ability of rotational thromboelastometry (ROTEM® , TEM International GmbH, Munich, Germany) as a point-of-care monitoring method. We evaluated 106 patients aged 3 months to 17 years undergoing LT for acute liver failure (ALF) and chronic liver disease, which consists of patients with cholestatic disease, metabolic/genetic disease, and cancer. A total of 731 ROTEM® measurements, including 301 ellagic acid to initiate clotting via the intrinsic pathway, 172 tissue factor to initiate the extrinsic clotting cascade (EXTEM), and 258 cytochalasin D to inhibit platelet activity reflecting fibrinogen (FIBTEM), were analyzed at predetermined time points (the preanhepatic, anhepatic, and postreperfusion phases). We simultaneously conducted conventional coagulation tests. In children with ALF, preanhepatic measurements of conventional coagulation tests and ROTEM® showed a more hypocoagulable state than other diseases. During LT, the coagulation profile was deranged, with a prolonged clotting time and reduced clot firmness, changes that were more profound in the cholestatic disease group. Maximum clot firmness (MCF) on EXTEM and FIBTEM were well correlated with the platelet count and fibrinogen concentration (r = 0.830, p < 0.001 and r = 0.739, p < 0.001, respectively). On the EXTEM, MCF with 30 mm predicted a platelet count <30,000/mm3 (area under the curve, 0.985), and 6 mm predicted a fibrinogen concentration <100 mg/dl on the FIBTEM (area under the curve, 0.876). However, the activated partial thromboplastin time and prothrombin time were significant but only weakly correlated with the clotting time on the ROTEM® . In children undergoing LT, coagulation profiles depend on the etiology for LT. During LT, ROTEM® parameters could help detect thrombocytopenia and hypofibrinogenemia and guide transfusion therapy as a point-of-care monitoring method.

Clinical implication of intraoperative ventricular-arterial coupling in pediatric patients undergoing ventricular septal defects repair: A retrospective cohort study.

BACKGROUND: Ventricular-arterial coupling is the ratio of arterial elastance to ventricular end-systolic elastance. AIMS: The objective of this study was to determine the clinical implication of intraoperative ventricular-arterial coupling derived from the pressure-area relationship using transesophageal echocardiography. METHODS: This retrospective study reviewed the medical records of 72 pediatric patients with ventricular septal defects who underwent corrective surgery with cardiopulmonary bypass. The single-beat modified method was used to assess ventricular-arterial coupling. Logistic regression analyses were performed to determine the correlation between ventricular-arterial coupling and early postoperative outcomes, including the maximum vasoactive-inotropic score, length of mechanical ventilation, and length of hospital stay. RESULTS: Ventricular-arterial coupling after cardiopulmonary bypass significantly increased (from 1.0 ± 0.4 to 1.4 ± 0.8, p < .001), indicating a disproportionate increase in the arterial elastance index (from 11.5 ± 5.1 to 19.8 ± 7.5 mmHg/cm2 /m2 , p < .001) compared with the ventricular end-systolic elastance index (from 13.0 ± 6.9 to 16.9 ± 9.0 mmHg/cm2 /m2 , p < .001). Logistic regression analyses revealed that high postoperative ventricular-arterial coupling was independently associated with higher postoperative maximum vasoactive-inotropic score (>10; odds ratio [OR], 8.04; 95% confidence interval [CI], 1.38-46.85, p = .020), longer postoperative mechanical ventilation (>15 h; OR: 11.00; 95% CI: 1.26-96.45, p = .030), and longer postoperative hospital stay (>7 days; OR: 2.98; 95% CI: 1.04-8.58, p = .043). CONCLUSIONS: Ventricular-arterial coupling can be easily obtained from the intraoperative transesophageal echocardiography in pediatric patients undergoing ventricular septal defects repair. High postoperative ventricular-arterial coupling is strongly associated with worse early postoperative outcomes. Ventricular-arterial coupling shows promise as an intraoperative analysis tool that can provide insight into the impact of interventions on cardiovascular performance and identify potential targets for treatment in this population.

Who are at high risk of mortality and morbidity among children with congenital heart disease undergoing noncardiac surgery?

With advances in the development of surgical and medical treatments for congenital heart disease (CHD), the population of children and adults with CHD is growing. This population requires multiple surgical and diagnostic imaging procedures. Therefore, general anesthesia is inevitable. In many studies, it has been reported that children with CHD have increased anesthesia risks when undergoing noncardiac surgeries compared to children without CHD. The highest risk group included patients with functional single ventricle, suprasystemic pulmonary hypertension, left ventricular outflow obstruction, and cardiomyopathy. In this review, we provide an overview of perioperative risks in children with CHD undergoing noncardiac surgeries and anesthetic considerations in patients classified as having the highest risk.

Use of a High-Flow Nasal Cannula in a Child With a Functional Single Ventricle and Difficult Airway.

Inducing anesthesia and securing the airway without disrupting the patient's hemodynamic state are challenging in pediatric patients with a functional single ventricle (FSV). Here, the authors report effective use of a high-flow nasal cannula (HFNC) as a tool in providing oxygen supplementation for airway management in pediatric FSV patients with a history of a difficult airway. A female patient, aged 5 years 7 months, was admitted for extracardiac conduit Fontan procedure. The patient had a history of multiple failed attempts at endotracheal intubation and was diagnosed with retrognathia and severe oral trismus of less than 1 finger width. The patient had another event of mask ventilation failure after propofol sedation during the preoperative computed tomography scan a day before the surgery. The patient's preoperative cardiac catheterization report revealed that the Qp/Qs ratio of 0.82 at room air, and the patient's peripheral oxygen saturation (SpO2) ranged from 70% to 80% at room air. On entering the operating room, the preoxygenation process began with HFNC at an oxygen flow of 16 L/min, with a fraction of inspired oxygen (FIO2) set at 95% after light sedation with an intravenous bolus of midazolam, 0.1 mg/kg. After 4 minutes of applying HFNC, with SpO2 rising from 76% to 98%, anesthetic medications were administered intravenously without a neuromuscular blocking agent to preserve spontaneous breathing. The patient was not ventilated with a facemask but instead left with HFNC in place for continuous supplemental oxygenation. The patient's airway was secured in a single attempt in 80 seconds. HFNC is an ideal option for oxygen supplementation during airway management of pediatric FSV patients, as their balance of pulmonary and systemic flow is perturbed easily by subtle physiologic alteration and therapeutic maneuvers during the induction of general anesthesia and highly susceptible to rapid desaturation and cardiovascular collapse, and should be considered as having a physiologically difficult airway.

COVID-19 in South Korea: epidemiological and spatiotemporal patterns of the spread and the role of aggressive diagnostic tests in the early phase.

BACKGROUND: South Korea experienced the novel coronavirus disease (COVID-19) outbreak in the early period; thus data from this country could provide significant implications for global mitigation strategies. This study reports how COVID-19 has spread in South Korea and examines the effects of rapid widespread diagnostic testing on the spread of the disease in the early epidemic phase. METHODS: We collected daily data on the number of confirmed cases, tests and deaths due to COVID-19 from 20 January to 13 April 2020. We estimated the spread pattern with a logistic growth model, calculated the daily reproduction number (Rt) and examined the fatality pattern of COVID-19. RESULTS: From the start date of the epidemic in Korea (18 February 2020), the time to peak and plateau were 15.2 and 25 days, respectively. The initial Rt was 3.9 [95% credible interval (CI) 3.7 to 4.2] and declined to <1 after 2 weeks. The initial epidemic doubling time was 3.8 days (3.4 to 4.2 days). The aggressive testing in the early days of the epidemic was associated with reduction in transmission speed of COVID-19. In addition, as of 13 April, the case fatality rate of COVID-19 in Korea was 2.1%, suggesting a positive effect of the targeted treatment policy for severe patients and medical resources. CONCLUSIONS: Our findings provide important information for establishing and revising action plans based on testing strategies and severe patient care systems, needed to address the unprecedented pandemic.

Sarcopenia as a prognostic factor for outcomes after isolated tricuspid valve surgery.

BACKGROUND: Sarcopenia, characterized by decreased skeletal muscle mass, is a comprehensive and objective marker of frailty and is associated with poor postoperative outcomes in adult surgery patients. We aimed to evaluate the prognostic implications of preoperative sarcopenia assessed by chest computed tomography in patients undergoing isolated tricuspid valve surgery. METHODS: This observational study retrospectively reviewed records of 144 consecutive adult patients who underwent isolated tricuspid valve surgery between January 2010 and December 2016. Preoperative chest computed tomography scans were used to measure the area of the erector spinae muscle and pectoralis muscle which was then indexed to height in meters squared. The total skeletal muscle index was defined as the sum of the right and left cross-sectional areas of the erector spinae muscle index and the pectoralis muscle index. Sarcopenia was defined as any total skeletal muscle index below the 50th sex-specific percentile. Multivariable Cox proportional hazard models were used to identify the independent association between preoperative sarcopenia and major 30-day postoperative complications. RESULTS: A total of 53 (36.8%) patients suffered from complications. Major 30-day postoperative complications occurred more frequently in patients with sarcopenia than in those without sarcopenia [46.6% (34/73) vs. 26.8% (19/71), p = 0.022]. With multivariable analyses, sarcopenia was independently associated with incidence of major 30-day postoperative complications (hazard ratio 2.24, 95% confidence interval 1.27-3.94, p = 0.005). CONCLUSIONS: Our study demonstrates a significant association between preoperative total skeletal muscle index and major 30-day postoperative complications in patients undergoing isolated tricuspid valve surgery.

A Population Pharmacokinetic Model of Intravenous Dexmedetomidine for Mechanically Ventilated Children after Neurosurgery.

Dexmedetomidine is a selective alpha-2 adrenergic agonist with concurrent sedative and analgesic effects, and it is being increasingly used in pediatric anesthesia and intensive care. This study aimed to investigate the pharmacokinetics of intravenous dexmedetomidine in mechanically ventilated children in the intensive care unit (ICU) after neurosurgery. Pediatric patients aged 2-12 years, who were mechanically ventilated in ICU after neurosurgery, were allocated into a low-dose (n = 15) or high-dose (n = 14) group. The low-dose group received dexmedetomidine at a loading dose of 0.25 µg/kg for 10 min, followed by a maintenance dose of 0.25 µg/kg/h for 50 min, whereas the high-dose group received dexmedetomidine at a loading dose of 0.5 µg/kg for 10 min, followed by a maintenance dose of 0.5 µg/kg/h for 50 min. Serial blood samples were collected for a pharmacokinetic analysis up to 480 min after the end of the infusion. The sedative effect of dexmedetomidine was assessed using the Bispectral Index and University of Michigan Sedation Scale. Adverse reactions, electrocardiography findings, and vital signs were monitored for a safety assessment. A population pharmacokinetic analysis was performed using non-linear mixed effects modeling. Dexmedetomidine induced a moderate-to-deep degree of sedation during infusion in both groups. The pharmacokinetics of dexmedetomidine were best described by a two-compartment disposition model with first-order elimination kinetics. The parameters were standardized for a body weight of 70 kg using an allometric power model. The population estimates (95% confidence interval) per 70 kg body weight were as follows: clearance of 81.0 (72.9-90.9) L/h, central volume of distribution of 64.2 (50.6-81.0) L, intercompartment clearance of 116.4 (90.6-156.0) L/h, and peripheral volume of distribution of 167 (132-217) L. No serious adverse reactions or hemodynamic changes requiring the discontinuation of dexmedetomidine were observed. Dexmedetomidine had increased clearance and volume of distribution in mechanically ventilated children in ICU after neurosurgery, thereby indicating the need to adjust the dosage to obtain a target plasma concentration.

Acute Change in Ventricular Contractility-Load Coupling After Corrective Surgery for Congenital Heart Defect: A Retrospective Cohort Study.

Ventricular performance and its loading condition change drastically after surgical correction of congenital heart defect. Pressure-volume loops analysis can provide quantitative information about ventriculo-arterial coupling (VAC) indicating the interaction between ventricular contractility and loading condition. Therefore, we investigated changes in VAC after corrective surgery for ventricular septal defect (VSD)/tetralogy of Fallot (TOF), and implication of ventriculo-arterial decoupling as a prognostic factor of post-operative outcomes. In children with VSD/TOF, pre- and post-operative arterial elastance (Ea), end-systolic ventricular elastance (Ees) and VAC (Ea/Ees) were non-invasively estimated using echocardiographic parameters. Post-operative outcomes included maximum vasoactive-inotropic score, the duration of mechanical ventilation and hospital stay. Preoperatively, patients with VSD had significantly lower Ea and Ees than patients with TOF; however, VAC were preserved in both. In patients with VSD, post-operative Ea increased disproportionately to change in Ees, resulting in increased VAC. Post-operative higher VAC in patients with VSD was independently associated with maximum vasoactive-inotropic score (odds ratio [OR] 63.9; 95% Confidence Interval [CI] 4.0-553.0; P = 0.003), prolonged mechanical ventilation (OR 6.3; 95% CI 1.1-37.8; P = 0.044) and longer hospitalization (OR 17.6; 95% CI 1.6-187.0; P = 0.018). In patients with TOF, Ea and Ees reduced post-operatively; however, VAC remained unchanged and was not associated with post-operative outcomes. Despite of different loading condition, preoperative VAC maintained in both of VSD and TOF. However, particularly in VSD patients, abrupt increase in post-operative loading state induces contractility-load decoupling, which leads to worse post-operative outcomes.

Low Muscle Mass as a Prognostic Factor for Early Postoperative Outcomes in Pediatric Patients Undergoing the Fontan Operation: A Retrospective Cohort Study.

The impact of low muscle mass on pediatric cardiac patients remains unclear. We investigated the impact of low muscle mass on early postoperative outcomes in patients undergoing the Fontan operation. The electronic medical records of 74 patients (aged <18 years) who underwent the Fontan operation were retrospectively reviewed. The cross-sectional areas of the erector spinae and pectoralis muscles were measured using preoperative chest computed tomography (CT), normalized to the body surface area, and combined to obtain the total skeletal muscle index (TSMI). Low muscle mass was defined as a TSMI value lower than the median TSMI for the second quintile. The incidence of major postoperative complications was higher in patients with low muscle mass than in those with high muscle mass (48% (15/31) versus 14% (6/43); P = 0.003). Multivariable analyses revealed that a higher TSMI was associated with a lower likelihood of an increased duration of intensive care unit (>5 days) and hospital stay (>14 days) (odds ratio (OR) 0.86; 95% confidence interval (CI) 0.77-0.96; P = 0.006 and OR 0.92; 95% CI 0.85-0.99; P = 0.035 per 1 cm2/m2 increase in TSMI) and incidence of major postoperative complications (OR 0.90; 95% CI 0.82-0.99; P = 0.039 per 1 cm2/m2 increase in TSMI). Preoperative low muscle mass was associated with poor early postoperative outcomes in pediatric patients undergoing the Fontan operation.

Effect of different fraction of inspired oxygen on development of atelectasis in mechanically ventilated children: A randomized controlled trial.

BACKGROUND: The use of high fraction of inspired oxygen (FI O2 ) can cause direct pulmonary toxicity and pulmonary complications. The purpose of this study was to evaluate the effect of different FI O2 on development of intraoperative atelectasis in mechanically ventilated children using lung ultrasound. METHODS: In this randomized controlled, patient- and sonographer-blinded trial, 86 children (≤6 years) undergoing noncardiac surgery were allocated into a low (n = 43) or high (n = 43) FI O2 group. The low FI O2 group consistently received 30% air-oxygen mixture during preoxygenation, ultrasound-guided recruitment maneuver, and mechanical ventilation. The high FI O2 group received 100% oxygen during preoxygenation and ultrasound-guided recruitment maneuver and 60% air-oxygen mixture during mechanical ventilation. Positive end-expiratory pressure of 5 cm H2 O was applied in both groups. Lung ultrasound was performed one minute after the start of mechanical ventilation and at the end of surgery in both groups. Primary outcome was significant atelectasis incidence (consolidation score of ≥2 in any region) on the postoperative lung ultrasound. Secondary outcomes included significant atelectasis incidence on the preoperative lung ultrasound, incidences of intra- and postoperative desaturation, and incidences of postoperative fever and postoperative pulmonary complications. RESULTS: Significant atelectasis incidence on the postoperative lung ultrasound was similar between the low and high FI O2 groups (28% vs 37%; Pearson chi-square value = 0.847; P = .357; OR 1.531; 95% CI 0.617-3.800). Significant atelectasis incidence on the preoperative lung ultrasound was also similar between the groups (12% vs 9%; Pearson chi-square value = 0.124; P = .725; OR 0.779; 95% CI 0.194-3.125). There were no statistically significant differences in the other secondary outcomes. CONCLUSIONS: FI O2 did not affect significant atelectasis formation in mechanically ventilated children who received ultrasound-guided recruitment maneuver and positive end-expiratory pressure.

Comparison of pulse pressure variation and pleth variability index in the prone position in pediatric patients under 2 years old.

BACKGROUND: The assessment of intravascular volume status is very important especially in children during anesthesia. Pulse pressure variation (PPV) and pleth variability index (PVI) are well known parameters for assessing intravascular volume status and fluid responsiveness. We compared PPV and PVI for children aged less than two years who underwent surgery in the prone position. METHODS: A total of 27 children were enrolled. We measured PPV and PVI at the same limb during surgery before and after changing the patients' position from supine to prone. We then compared PPV and PVI at each period using Bland-Altman plot for bias between the two parameters and for any correlation. We also examined the difference between before and after the position change for each parameter, along with peak inspiratory pressure, heart rate and mean blood pressure. RESULTS: The bias between PPV and PVI was -2.2% with a 95% limits of agreement of -18.8% to 14.5%, not showing significant correlation at any period. Both PPV and PVI showed no significant difference before and after the position change. CONCLUSIONS: No significant correlation between PVI and PPV was observed in children undergoing surgery in the prone position. Further studies relating PVI, PPV, and fluid responsiveness via adequate cardiac output estimation in children aged less than 2 years are required.

Accuracy of pulse oximeters at low oxygen saturations in children with congenital cyanotic heart disease: An observational study.

BACKGROUND: Pulse oximetry overestimates arterial oxygen saturation (SaO2 ) at less than 90% saturation in cyanotic children. The Masimo Blue sensor (Masimo Corp., Irvine, CA) is a pulse oximetry sensor developed for use in children with cyanosis. However, there remains a lack of research in actual clinical practice. AIMS: We evaluated the intraoperative performance of three different pulse oximeters to measure oxyhemoglobin saturation (SpO2 ) at low saturations in pediatric patients with cyanotic heart disease and the influence of clinical variables (SaO2 , hemoglobin concentration, perfusion index, and weight) on the accuracy of the sensors. METHODS: This prospective observational study compared SpO2 measured using three pulse oximeters (Masimo Blue [Masimo Corp., Irvine, CA]; Masimo LNCS, and Nellcor [Medtronic, Dublin, Ireland]) at selected SaO2 ranges (≥85%, 75%-84%, 60%-74%, and < 60%). Accuracy was evaluated according to bias and Bland-Altman analysis with appropriate correction for multiple measurements. Relationships between bias and clinical variables were assessed using a generalized estimating equation. RESULTS: Two hundred and fifty-eight samples were analyzed. The mean overall bias (limits of agreement) of Masimo Blue, Masimo LNCS, and Nellcor sensor was -5.3 (-20.9 to 10.3%), -7.4 (-21.9 to 7.1%), and -7.4 (-22.5 to 15.1%), respectively. However, there was no difference in bias among the three sensors at SaO2 <60%. Generalized estimating equation showed that SaO2 value was associated with bias of all sensors. Perfusion index affected the bias of Blue sensor and LNCS sensor, and patients' weight was associated with bias of Nellcor sensor. CONCLUSION: Masimo blue sensor demonstrated overall lower bias compared to the other two sensors. However, the accuracy of all sensors was similarly poor at SaO2 less than 60%. Bias was influenced by SaO2 , perfusion index, and body weight.

Respiratory Variation of Internal Carotid Artery Blood Flow Peak Velocity Measured by Transfontanelle Ultrasound to Predict Fluid Responsiveness in Infants: A Prospective Observational Study.

BACKGROUND: Cranial sonography is a widely used point-of-care modality in infants. The authors evaluated that the respiratory variation of the internal carotid artery blood flow peak velocity as measured using transfontanelle ultrasound can predict fluid responsiveness in infants. METHODS: This prospective observational study included 30 infants undergoing cardiac surgery. Following closure of the sternum, before and after the administration of 10ml · kg crystalloid, the respiratory variation of the aorta blood flow peak velocity, pulse pressure variation, and central venous pressure were obtained. The respiratory variation of the internal carotid artery blood flow peak velocity was measured using transfontanelle ultrasound. Response to fluid administration was defined as an increase in stroke volume index, as measured with transesophageal echocardiography, greater than 15% of baseline. RESULTS: Seventeen subjects (57%) were responders to volume expansion. Before fluid loading, the respiratory variation of the internal carotid artery and the aorta blood flow peak velocity (means ± SD) of the responders were 12.6 ± 3.3% and 16.0 ± 3.8%, and those of the nonresponders were 8.2 ± 3.2% and 10.9 ± 3.5%, respectively. Receiver operating characteristic curve analysis showed that the respiratory variation of the internal carotid artery and the aorta blood flow peak velocity could predict fluid responsiveness; the area under the curve was 0.828 (P < 0.0001; 95% CI, 0.647 to 0.940) and 0.86 (P = 0.0001; 95% CI, 0.684 to 0.959), respectively. The cutoff values of the respiratory variation of the internal carotid artery and the aorta blood flow peak velocity were 7.8% (sensitivity, 94%; specificity, 69%) and 13% (sensitivity, 77%; specificity, 92%), respectively. CONCLUSIONS: The respiratory variation of the internal carotid artery blood flow peak velocity as measured using transfontanelle ultrasound predicted an increase in stroke volume in response to fluid. Further research is required to establish any wider generalizability of the results.

Manual vs pressure-controlled facemask ventilation during the induction of general anesthesia in children: A prospective randomized controlled study.

BACKGROUND: Gastric insufflation frequently occurs during facemask ventilation in children. In the present study, we compared the incidence of gastric insufflation between pressure-controlled facemask ventilation and manual facemask ventilation during general anesthesia induction in children. METHODS: Children in the pressure-controlled ventilation group (n = 76) received pressure-controlled facemask ventilation at an inspiratory pressure of 13 cm H2 O. In the manual ventilation group (n = 75), facemask ventilation was manually performed by anesthesiologists, who tried to maintain an inspiratory pressure of 13 cm H2 O. The adjustable pressure limiting valve was set at 13 cm H2 O. The incidence of gastric insufflation during 90 seconds after the initiation of ventilation was assessed using epigastric auscultation and gastric ultrasonography. RESULTS: The incidence of gastric insufflation was significantly higher in the manual  facemask ventilation group than in the pressure-controlled ventilation group (48% vs 12%, respectively; odds ratio 7.78, 95% confidence interval [CI] 3.38-17.9; P < 0.001). The mean peak airway pressure during ventilation was significantly higher in the manual ventilation group than in the pressure-controlled ventilation group (16.1 [3.0] cm H2 O vs 13.0 [0.1] cm H2 O; 95% CI of differences, 2.36-3.71 cm H2 O; P < 0.001). The manual ventilation group exhibited a wide peak airway pressure  range (11-26 cm H2 O) and a wide variation of tidal volume (0-7.0 mL/kg) compared with those of the pressure-controlled ventilation group (13-14 cm H2 O and 0.6-16.0 mL/kg, respectively). CONCLUSION: At an inspiratory pressure of 13 cm H2 O, pressure-controlled ventilation may be more effective than manual ventilation in preventing gastric insufflation while providing stable ventilation in children.

Optimal inspiratory pressure for face mask ventilation in paralyzed and unparalyzed children to prevent gastric insufflation: a prospective, randomized, non-blinded study.

BACKGROUND: Gastric insufflation is common during face mask ventilation and results in unfavourable respiratory events in children. The purpose of this study was to evaluate the effect of a muscle relaxant on gastric insufflation and determine the optimal inspiratory pressure during face mask ventilation in children. METHODS: Children aged one month to five years were randomly assigned to neuromuscular blocker (NM) or non-neuromuscular blocker (non-NM) groups. After administering intravenous anesthetics, face mask ventilation commenced via pressure-controlled mechanical ventilator. Initial inspiratory pressure was 10 cmH2O and was increased by 2 cmH2O until gastric insufflation was detected via gastric ultrasonography or epigastric auscultation. The primary outcome was the difference in the inspiratory pressure that causes gastric insufflation between the two groups. Diagnostic methods that detect gastric insufflation first were also evaluated. RESULTS: There was no significant difference in the median [interquartile range] inspiratory pressure inducing gastric insufflation between the non-NM (n = 52) and NM groups (n = 60) (18 [16-18] cmH2O vs 18.0 [16-20] cmH2O; median difference, 0 cmH2O; 95% confidence interval [CI], 0 to 2; P = 0.57). The incidence of gastric insufflation increased with increasing inspiratory pressure. Gastric insufflation was detected first by ultrasonography in 44% and by epigastric auscultation in 19% of the non-NM group (difference in percentage, 25%; 95% CI, 6 to 42; P = 0.006) and by ultrasonography in 73% and by epigastric auscultation in 7% of the NM group (difference in percentage, 66%; 95% CI, 50 to 78; P < 0.001). CONCLUSIONS: A neuromuscular blocking agent has minimal effect on the inspiratory pressure that causes gastric insufflation during face mask ventilation in children. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT02471521); registered 15 June 2015.

Risk factors of acute kidney injury in children after cardiac surgery.

BACKGROUND: The objective of this retrospective study was to determine the risk factors for acute kidney injury (AKI), including albumin, in children who underwent cardiac surgery. In addition, we evaluated the association between preoperative serum albumin level and postoperative AKI in these patients. METHODS: This retrospective study included 505 pediatric patients who underwent congenital cardiac surgery. Preoperative and perioperative risk factors for AKI, including serum albumin level, were assessed. AKI incidence within 7 postoperative days was determined using the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Multivariable logistic regression analysis was performed to evaluate the association between possible risk factors and postoperative AKI. RESULTS: Of 505 pediatric patients, 185 (36.6%) developed postoperative AKI. The preoperative serum albumin level was associated with postoperative AKI (odds ratio [OR] 0.506, 95% confidence interval [CI] 0.325-0.788; P = 0.003). Other independent factors associated with AKI were age <12 months (OR 1.911, 95% CI 1.166-3.132; P = 0.007), preoperative pulmonary hypertension (OR 1.853, 95% CI 1.182-2.907; P = 0.01), and cardiopulmonary bypass (CPB) duration (OR 1.006, 95% CI 1.003-1.009; P = 0.002). Patients with AKI had higher incidence of postoperative complications, longer mechanical ventilation times, and more prolonged intensive care unit and hospital stays than patients without AKI. CONCLUSIONS: Preoperative serum albumin level, age <12 months, preoperative pulmonary hypertension, and CPB duration were associated with risk for postoperative AKI in children who underwent congenital cardiac surgery.