Polyphasic molecular approach to the characterization of methanogens in the saliva of Tunisian adults

OBJECTIVES

Methanogenic archaea are a minor component of human oral microbiota. Due to their relatively low abundance, the detection of these neglected microorganisms is challenging. This study concerns the presence of methanogens in salivary samples collected from Tunisian adults to evaluate their prevalence and burden using a polyphasic molecular approach.

METHODS

A total of 43 saliva samples were included. Metagenomic and standard 16S rRNA sequencing were performed as an initial screening to detect the presence of methanogens in the oral microbiota of Tunisian adults. Further investigations were performed using specific quantitative real-time PCR targeting Methanobrevibacter oralis and Methanobrevibacter smithii.

RESULTS

Methanobrevibacter was detected in 5/43 (11.62 %) saliva samples after metagenomic 16S rRNA data analysis. The presence of M. oralis was confirmed in 6/43 samples by standard 16S rRNA sequencing. Using real-time PCR, methanogens were detected in 35/43 (81.39 %) samples, including 62.79 % positive for M. oralis and 76.74 % positive for M. smithii. These findings reflect the high prevalence of both methanogens, revealed by the high sensitivity of the real-time PCR approach. Interestingly, we also noted a significant statistical association between the detection of M. smithii and poor adherence to a Mediterranean diet, indicating the impact of diet on M. smithii prevalence.

CONCLUSION

Our study showed the presence of methanogens in the oral microbiota of Tunisian adults with an unprecedented relatively high prevalence. Choice of methodology is also central to picturing the real prevalence and diversity of such minor taxa in the oral microbiota.

Continuous cerebral blood flow monitoring: What should we do with these extra numbers?

NeoDoppler is a noninvasive monitoring device that can be attached to a patient's head to provide real-time continuous cerebral Doppler evaluation. A feasibility study shows that it can be used in operating theatres during anaesthesia to potentially guide haemodynamic management. We discuss the impact of this new device and which further research would be necessary to find its role in clinical practice.

Automatic Prediction of Paediatric Cardiac Output From Echocardiograms Using Deep Learning Models

Background

Cardiac output (CO) perturbations are common and cause significant morbidity and mortality. Accurate CO assessment is crucial for guiding treatment in anaesthesia and critical care, but measurement is difficult, even for experts. Artificial intelligence methods show promise as alternatives for accurate, rapid CO assessment.

Methods

We reviewed paediatric echocardiograms with normal CO and a dilated cardiomyopathy patient group with reduced CO. Experts measured the left ventricular outflow tract diameter, velocity time integral, CO, and cardiac index (CI). EchoNet-Dynamic is a deep learning model for estimation of ejection fraction in adults. We modified this model to predict the left ventricular outflow tract diameter and retrained it on paediatric data. We developed a novel deep learning approach for velocity time integral estimation. The combined models enable automatic prediction of CO. We evaluated the models against expert measurements. Primary outcomes were root-mean-squared error, mean absolute error, mean average percentage error, and coefficient of determination (R2).

Results

In a test set unused during training, CI was estimated with the root-mean-squared error of 0.389 L/min/m2, mean absolute error of 0.321 L/min/m2, mean average percentage error of 10.8%, and R2 of 0.755. The Bland-Altman analysis showed that the models estimated CI with a bias of +0.14 L/min/m2 and 95% limits of agreement -0.58 to 0.86 L/min/m2.

Conclusions

Our model estimated CO with strong correlation to ground truth and a bias of 0.17 L/min, better than many CO measurements in paediatrics. Model pretraining enabled accurate estimation despite a small dataset. Potential uses include supporting clinicians in real-time bedside calculation of CO, identification of low-CO states, and treatment responses.

Point-of-care ultrasonography to predict fluid responsiveness in children: A systematic review and meta-analysis

BACKGROUND

Point-of-care ultrasonography (POCUS) is proposed as a valuable method for hemodynamic monitoring and several ultrasound-based predictors of fluid responsiveness have been studied. The main objective of this study was to assess the accuracy of these predictors in children.

METHODS

PubMed, Embase, Scopus, ClinicalTrials.gov, and Cochrane Library databases were searched for relevant publications through July 2022. Pediatric studies reporting accuracy estimates of ultrasonographic predictors of fluid responsiveness were included since they had used a standard definition of fluid responsiveness and had performed an adequate fluid challenge.

RESULTS

Twenty-three studies involving 1028 fluid boluses were included, and 12 predictors were identified. A positive response to fluid infusion was observed in 59.7% of cases. The vast majority of participants were mechanically ventilated (93.4%). The respiratory variation in aortic blood flow peak velocity (∆Vpeak) was the most studied predictor, followed by the respiratory variation in inferior vena cava diameter (∆IVC). The pooled sensitivity and specificity of ∆Vpeak were 0.84 (95% CI, 0.76-0.90) and 0.82 (95% CI, 0.75-0.87), respectively, and the area under the summary receiver operating characteristic curve (AUSROC) was 0.89 (95% CI, 0.86-0.92). The ∆IVC presented a pooled sensitivity and specificity of 0.79 (95% CI, 0.62-0.90) and 0.70 (95% CI, 0.51-0.84), respectively, and an AUSROC of 0.81 (95% CI, 0.78-0.85). Significant heterogeneity in accuracy estimates across studies was observed.

CONCLUSIONS

POCUS has the potential to accurately predict fluid responsiveness in children. However, only ∆Vpeak was found to be a reliable predictor. There is a lack of evidence supporting the use of POCUS to guide fluid therapy in spontaneously breathing children.

Fluid bolus administration in children, who responds and how? A systematic review and meta-analysis

BACKGROUND

Fluid boluses are frequently utilized in children. Despite their frequency of use, there is little objective data regarding the utility of fluid boluses, who they benefit the most, and what the effects are.

AIMS

This study aimed to conduct pooled analyses to identify those who may be more likely to respond to fluid boluses as well as characterize clinical changes associated with fluid boluses.

METHODS

A systematic review of the literature and meta-analysis was conducted to identify pediatric studies investigating the response to fluid boluses and clinical changes associated with fluid boluses.

RESULTS

A total of 15 studies with 637 patients were included in the final analyses with a mean age of 650 days ± 821.01 (95% CI 586 to 714) and a mean weight of 10.5 kg ± 7.19 (95% CI 9.94 to 11.1). The mean bolus volume was 12.14 ml/kg ± 4.09 (95% CI 11.8 to 12.5) given over a mean of 19.55 min ± 10.16 (95% CI 18.8 to 20.3). The following baseline characteristics were associated with increased likelihood of response [represented in mean difference (95% CI)]: greater age [207.2 days (140.8 to 273.2)], lower cardiac index [-0.5 ml/min/m² (-0.9 to -0.3)], and lower stroke volume [-5.1 ml/m² (-7.9 to -2.3)]. The following clinical parameters significantly changed after a fluid bolus: decreased HR [-5.6 bpm (-9.8 to -1.3)], increased systolic blood pressure [7.7 mmHg (1.0 to 14.4)], increased mean arterial blood pressure [5.5 mmHg (3.1 to 7.8)], increased cardiac index [0.3 ml/min/m² (0.1 to 0.6)], increased stroke volume [4.3 ml/m² (3.5 to 5.2)], increased central venous pressure [2.2 mmHg (1.1 to 3.3)], and increased systemic vascular resistance [2.1 woods units/m² (0.1 to 4.2)].

CONCLUSION

Fluid blouses increase arterial blood pressure or cardiac output by 10% in approximately 56% of pediatric patients. Fluid blouses lead to significant decrease in HR and significant increases in cardiac output, stroke volume, and systemic vascular resistance. Limited published data are available on the effects of fluid blouses on systemic oxygen delivery.

Predictive Value of the Respiratory Variation in Inferior Vena Cava Diameter for Ventilated Children With Septic Shock

OBJECTIVES

This study aimed to investigate the predictive utility of respiratory variations of inferior vena cava diameters on fluid responsiveness in children with septic shock.

DESIGN

A prospective observational single-center study.

SETTING

A pediatric intensive care unit in a tertiary hospital in China.

PARTICIPANTS

Patients with sepsis shock who require invasive mechanical ventilation were recruited between 1 December 2017 and 1 November 2021.

INTERVENTIONS AND MEASUREMENTS

Volume expansion (VE) was induced by a 30-min infusion of 20 ml/kg of normal saline. Hemodynamics indexes were obtained through bedside transthoracic echocardiography (TTE) measurement and calculation.

RESULTS

A total of 86 patients were enrolled in this study, among them, 45 patients (52.3%) were considered to be non-responders (NR), with an increase in stroke volume variation (SVV) <15% after VE. Multivariate logistic analysis showed that ΔIVC (adjusted OR = 1.615, 95% CI 1.092-2.215, p = 0.012) was the significant predictor associated with the fluid responsiveness. The area under the ROC of ΔIVC was 0.922 (95% CI: 0.829-1.000, p < 0.01), and the cutoff value of ΔIVC used to predict fluid responsiveness was 28.5%, with a sensitivity and specificity of 95.4 and 68.5%, respectively.

CONCLUSIONS

The ΔIVC was found to have a potential value in predicting fluid responsiveness in mechanically ventilated children with septic shock.

Diagnostic accuracy of stroke volume variation for predicting fluid responsiveness in children undergoing cardiac surgery: A systematic review and meta-analysis

BACKGROUND

Stroke volume variation appears to be reliable for predicting fluid responsiveness in adults, and its predictive value in pediatric patients has been recently reported. However, its predictive value in children undergoing cardiac surgery is unclear.

METHODS

A review and meta-analysis were performed on the diagnostic utility of stroke volume variation for predicting fluid responsiveness in children undergoing cardiac surgery. All relevant articles for prospective research assessing the value of stroke volume variation were searched in the Embase, MEDLINE (PubMed), and Cochrane databases through March 2020. The primary outcome was the accuracy of stroke volume variation for predicting fluid responsiveness in children. The combined data were analyzed by a meta-analysis. Publication quality was assessed using the QUADAS (quality assessment for studies of diagnostic accuracy, maximum score) standard guidelines.

RESULTS

Six articles were included in the meta-analysis, following the search strategy. A total of 251 children were included from 6 prospective studies. Fluid therapy for all patients used crystalloids or colloids. The results of the analysis revealed a pooled diagnostic odds ratio of 8.23 (95% CI: 3.07-22.11), pooled sensitivity of 0.73 (95% CI: 0.64-0.80), and pooled specificity of 0.66 (95% CI: 0.58-0.74). Additionally, the overall area of the summary receiver operating characteristic curve was 0.78. There was significant moderate heterogeneity in these studies (p < .05, I²  = 42.1%) due to thresholds.

CONCLUSIONS

There was some heterogeneity due to thresholds in the included studies. An evaluation of stroke volume variation may represent a reliable predictor of fluid responsiveness in children undergoing cardiac surgery. After operative cardiac output optimization, the possible impact of goal-directed fluid treatment depending on stroke volume variation on the perioperative outcome in the children population should subsequently be assessed.

Novel Method of Calculating Pulse Pressure Variation to Predict Fluid Responsiveness to Transfusion in Very Low Birth Weight Infants

A novel technique was used to calculate pulse pressure variation. The algorithm reliably predicted fluid responsiveness to transfusion, with a receiver operating characteristic area under the curve of 0.89. This technique may assist clinicians in the management of fluids and vasoactive medications for premature infants.

Determination of the optimal dose of ephedrine in the treatment of arterial hypotension due to general anesthesia in neonates and infants below 6 months old: the ephedrine study protocol for a randomized, open-label, controlled, dose escalation trial

BACKGROUND

Arterial hypotension induced by general anesthesia is commonly identified as a risk factor of morbidity, especially neurological, after cardiac or noncardiac surgery in adults and children. Intraoperative hypotension is observed with sevoflurane anesthesia in children, in particular in neonates, infants younger than 6 months, and preterm babies. Ephedrine is commonly used to treat intraoperative hypotension. It is an attractive therapeutic, due to its dual action on receptors alpha and beta and its possible peripheral intravenous infusion. There are few data in the literature on the use of ephedrine in the context of pediatric anesthesia. The actual recommended dose of ephedrine (0.1 to 0.2 mg/Kg) frequently leads to a therapeutic failure in neonates and infants up to 6 months of age. The use of higher doses would probably lead to a better correction of hypotension in this population. The objective of our project is to determine the optimal dose of ephedrine for the treatment of hypotension after induction of general anesthesia with sevoflurane, in neonates and infants up to 6 months of age.

METHODS

The ephedrine study is a prospective, randomized, open-label, controlled, dose-escalation trial. The dose escalation consists of 6 successive cohorts of 20 subjects. The doses studied are 0.6, 0.8, 1, 1.2, and 1.4 mg/kg. The dose chosen as the reference is 0.1 mg/kg, the actual recommended dose. Neonates and infants younger than 6 months, males and females, including preterm babies who undergo a surgery with general anesthesia inducted with sevoflurane were eligible. Parents of the subject were informed. Then, the subjects were randomized if presenting a decrease in mean blood pressure superior to 20% of their initial mean blood pressure (before induction of anesthesia), despite a vascular filling with sodium chloride 0.9%. The primary outcome is the success of the therapy defined as an mBP superior to 80% of the baseline mBP (prior to anesthesia) within 10 min post ephedrine administration. The subjects were followed-up for 3 days postanesthesia.

DISCUSSION

This study is the first randomized, controlled trial intending to determine the optimal dose of ephedrine to treat hypotension in neonates and infants below 6 months old.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02384876 . Registered on March 2015.

Does a two-minute mini-fluid challenge predict fluid responsiveness in pediatric patients under general anesthesia?

BACKGROUND

Very little evidence for predictive markers of fluid responsiveness has been reported in children as compared to adults. The impact of hypovolemia or hypervolemia on morbidity has driven interest in the fluid challenge titration strategy.

AIM

The objective of this study was to explore the ability of a 3 mL kg^-1 mini-fluid challenge over 2 minutes to predict fluid responsiveness in children under controlled ventilation.

METHODS

Children scheduled for surgery under general anesthesia were included and received a fluid challenge of 15 mL kg^-1 of crystalloid prior to incision administered over 10 minutes in two steps: 3 mL kg^-1 over 2 minutes then 12 mL kg^-1 over 8 minutes. Fluid responsiveness was defined as a change of ≥10% in cardiac output estimated by left ventricular outflow tract velocity time integral (VTI) as measured by transthoracic ultrasound before and after the fluid challenge of 15 mL kg^-1 .

RESULTS

Of the 55 patients included in the analysis, 43 were fluid responders. The increase in the VTI after the mini-fluid challenge (ΔVTI_miniFC ) predicted fluid responsiveness with an area under the receiver operating characteristic curve of 0.77; 95% CI (0.63-0.87), P = .004. Considering the least significant change which was 7.9%; 95% CI (6-10), the threshold was 8% with a sensitivity of 53%; 95% CI (38-68); and a specificity of 77%; 95% CI (54-100).

CONCLUSION

ΔVTI_miniFC weakly predicted the effects of a fluid challenge of 15 mL kg^-1 of crystalloid in anesthetized children under controlled mechanical ventilation.

Respiratory Variation of Internal Carotid Artery Blood Flow Peak Velocity Measured by Transfontanelle Ultrasound to Predict Fluid Responsiveness in Infants

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

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–1 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 &lt; 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.

A healthy measure of monitoring fundamentals!

Monitoring represents a seminal part of modern anesthesia but it is imperative that clinicians and health care staff understand the fundamentals of measurements to correctly understand, apply, and at times discard various monitoring options. The world of measurements is a very precise science that needs to be fully acknowledged. This communication aims at highlighting certain issues relevant to everyday clinical monitoring.

Carotid Flow Time Test Performance for the Detection of Dehydration in Children With Diarrhea

OBJECTIVES

Unstructured clinical assessments of dehydration in children are inaccurate. Point-of-care ultrasound is a noninvasive diagnostic tool that can help evaluate the volume status; the corrected carotid artery flow time has been shown to predict volume depletion in adults. We sought to determine the ability of the corrected carotid artery flow time to identify dehydration in a population of children presenting with acute diarrhea in Dhaka, Bangladesh.

METHODS

Children presenting with acute diarrhea were recruited and rehydrated according to hospital protocols. The corrected carotid artery flow time was measured at the time of presentation. The percentage of weight change with rehydration was used to categorize each child's dehydration as severe (>9%), some (3%-9%), or none (<3%). A receiver operating characteristic curve was constructed to test the performance of the corrected carotid artery flow time for detecting severe dehydration. Linear regression was used to model the relationship between the corrected carotid artery flow time and percentage of dehydration.

RESULTS

A total of 350 children (0-60 months) were enrolled. The mean corrected carotid artery flow time was 326 milliseconds (interquartile range, 295-351 milliseconds). The area under the receiver operating characteristic curve for the detection of severe dehydration was 0.51 (95% confidence interval, 0.42, 0.61). Linear regression modeling showed a weak association between the flow time and dehydration.

CONCLUSIONS

The corrected carotid artery flow time was a poor predictor of severe dehydration in this population of children with diarrhea.

Evaluation of the dynamic predictors of fluid responsiveness in dogs receiving goal-directed fluid therapy

OBJECTIVES

Goal-directed fluid therapy (GDFT) based on pulse pressure variation (PPV) was used in anaesthetized dogs undergoing abdominal surgeries. The aims were 1) to evaluate the success rate of the PPV ≥13% in detecting fluid responsiveness [delta stroke volume (ΔSV) ≥10%]; 2) to assess the correlation between PPV, systolic pressure variation (SPV), Plethysmograph Variability Index (PVI) and central venous pressure (CVP) and 3) to establish the threshold value for the PVI that would predict a PPV value of ≥13% and indirectly discriminate responders from nonresponders to fluid therapy.

STUDY DESIGN

Clinical, prospective, interventional study.

ANIMALS

A total of 63 client-owned dogs scheduled for abdominal procedures.

METHODS

PPV and SPV were calculated manually from the invasive blood pressure trace on the Datex monitor. PVI was recorded from the Masimo pulse oximeter. Fluid challenge (10 mL kg^-1 Compound Sodium Lactate) was performed when PPV was ≥13% and/or mean arterial pressure (MAP) < 60 mmHg. Fluid responsiveness was assessed by the transoesophageal Doppler probe. Cardiovascular parameters (heart rate, MAP, PPV, SPV, PVI, SV and if available, CVP) were measured before and after each fluid intervention.

RESULTS

PPV ≥ 13% reliably predicted fluid responsiveness in 82.9% of cases. There was positive correlation between PPV and SPV (r = 0.84%), PPV and logPVI (r = 0.46) as well as SPV and logPVI (r = 0.45). Noninvasive PVI value ≥13% should predict PPV threshold value (13%) with 97% sensitivity and 68% specificity. There was no statistically significant correlation between PPV and CVP.

CONCLUSIONS

PPV is a useful clinical tool to detect occult hypovolaemia and predict cardiovascular response to fluid challenge. Use of PPV is recommended as a part of GDFT in dogs undergoing abdominal procedures.

Preemptive hemodynamic intervention restricting the administration of fluids attenuates lung edema progression in oleic acid-induced lung injury

OBJECTIVE

A study is made of the influence of preemptive hemodynamic intervention restricting fluid administration upon the development of oleic acid-induced lung injury.

DESIGN

A randomized in vivo study in rabbits was carried out.

SETTING

University research laboratory.

SUBJECTS

Sixteen anesthetized, mechanically ventilated rabbits.

VARIABLES

Hemodynamic measurements obtained by transesophageal Doppler signal. Respiratory mechanics computed by a least square fitting method. Lung edema assessed by the ratio of wet weight to dry weight of the right lung. Histological examination of the left lung.

INTERVENTIONS

Animals were randomly assigned to either the early protective lung strategy (EPLS) (n=8) or the early protective hemodynamic strategy (EPHS) (n=8). In both groups, lung injury was induced by the intravenous infusion of oleic acid (OA) (0.133mlkg^-1h^-1 for 2h). At the same time, the EPLS group received 15mlkg^-1h^-1 of Ringer lactate solution, while the EPHS group received 30mlkg^-1h^-1. Measurements were obtained at baseline and 1 and 2h after starting OA infusion.

RESULTS

After 2h, the cardiac index decreased in the EPLS group (p<0.05), whereas in the EPHS group it remained unchanged. Lung compliance decreased significantly only in the EPHS group (p<0.05). Lung edema was greater in the EPHS group (p<0.05). Histological damage proved similar in both groups (p=0.4).

CONCLUSIONS

In this experimental model of early lung injury, lung edema progression was attenuated by preemptively restricting the administration of fluids.

The Role of Focused Echocardiography in Pediatric Intensive Care: A Critical Appraisal

Echocardiography is a key tool for hemodynamic assessment in Intensive Care Units (ICU). Focused echocardiography performed by nonspecialist physicians has a limited scope, and the most relevant parameters assessed by focused echocardiography in Pediatric ICU are left ventricular systolic function, fluid responsiveness, cardiac tamponade and pulmonary hypertension. Proper ability building of pediatric emergency care physicians and intensivists to perform focused echocardiography is feasible and provides improved care of severely ill children and thus should be encouraged.

Low predictability of three different noninvasive methods to determine fluid responsiveness in critically ill children

OBJECTIVE

To predict fluid responsiveness by noninvasive methods in a pediatric critical care population.

DESIGN

Prospective observational clinical trial.

SETTING

PICU in a tertiary care academic hospital.

PATIENTS

Thirty-one pediatric patients aged from 1 day to 13 years under mechanical ventilation and on catecholamine support.

INTERVENTIONS

We tested three noninvasive methods to predict fluid responsiveness: an esophageal Doppler system (CardioQ), a pulse contour analysis algorithm system (LiDCOrapid), and respiratory variations in vena cava inferior diameter. Stroke volume index was measured by transthoracic echocardiography before and after fluid challenge to determine fluid responders. Infusion of 10 mL/kg hydroxyethylstarch 130/0.4.

MEASUREMENTS AND MAIN RESULTS

Predictability of fluid responsiveness was only found in Doppler peak velocity of descending aortal blood flow. Increased peak velocity with reduction after fluid bolus was predictive for nonresponding to IV fluid challenge. Sensitivity and specificity of peak velocity were 69% and 73%, respectively. The cut point was set at 135.5 cm/s. The lower the Doppler peak velocity, the higher was the probability for a fluid response. Neither stroke volume variations nor respiratory variations in vena cava inferior diameter during mechanical ventilation were useful in predicting fluid responsiveness in this pediatric patient population. None of the children had abdominal hypertension measured by bladder pressure.

CONCLUSIONS

Dynamic preload variables such as stroke volume variation or respiratory variations in vena cava inferior diameter may not be useful for predicting fluid responsiveness in certain pediatric patient populations. Esophageal Doppler peak velocity was predictive of fluid responsiveness where a target value of more than 135,5 cm/s may be a signal to terminate further fluid challenges. This target value may be different in different age groups, as esophageal Doppler peak velocity varies with age.

Pressure recording analytical method and bioreactance for stroke volume index monitoring during pediatric cardiac surgery

BACKGROUND

It is currently uncertain which hemodynamic monitoring device reliably measures stroke volume and tracks cardiac output changes in pediatric cardiac surgery patients.

OBJECTIVE

To evaluate the difference between stroke volume index (SVI) measured by pressure recording analytical method (PRAM) and bioreactance and their ability to track changes after a therapeutic intervention.

METHODS

A single-center prospective observational cohort study in children undergoing cardiac surgery with cardiopulmonary bypass (CPB) was conducted. Twenty children below 20 kg with median (interquartile range) weight of 5.3 kg (4.1-7.8) and age of 6 months (3-20) were enrolled. Data were collected after anesthesia induction, at the end of CPB, before fluid administration and after fluid administration. Overall, median-IQR PRAM SVI values (23 ml·m(-2), 19-27) were significantly higher than bioreactance SVI (15 ml·m(-2), 12-25, P = 0.0001). Correlation (r(2) ) between the two methods was 0.15 (P = 0.0003). The mean difference between the measurements (bias) was 5.7 ml·m(-2) with a standard deviation of 9.6 (95% limits of agreement ranged from -13 to 24 ml·m(-2)). Percentage error was 91.7%. Baseline SVI appeared to be similar, but PRAM SVI was systematically greater than bioreactance thereafter, with the highest gap after the fluid loading phase: 13 (12-18) ml·m(-2) vs. 23 (19-25) ml·m(-2), respectively, P = 0.0013. A multivariable regression model showed that a significant independent inverse correlation with patients' body weight predicted the CI difference between the two methods after fluid challenge (β coefficient -0.12, P = 0.013).

CONCLUSIONS

Pressure recording analytical method and bioreactance provided similar SVI estimation at stable hemodynamic conditions, while bioreactance SVI values appeared significantly lower than PRAM at the end of CPB and after fluid replacement.

Stroke volume variation and indexed stroke volume measured using bioreactance predict fluid responsiveness in postoperative children

BACKGROUND

Postoperative fluid management can be challenging in children after haemorrhagic surgery. The goal of this study was to assess the ability of dynamic cardiovascular variables measured using bioreactance (NICOM®, Cheetah Medical, Tel Aviv, Israel) to predict fluid responsiveness in postoperative children.

METHODS

Children sedated and mechanically ventilated, who require volume expansion (VE) during the immediate postoperative period, were included. Indexed stroke volume (SVi), cardiac index, and stroke volume variation (SVV) were measured using the NICOM® device. Responders (Rs) to VE were patients showing an increase in SV measured using transthoracic echocardiography of at least 15% after VE. Data are median [95% confidence interval (CI)].

RESULTS

Thirty-one patients were included, but one patient was excluded because of the lack of calibration of the NICOM® device. Before VE, SVi [33 (95% CI 31-36) vs 24 (95% CI 21-28) ml m(-2); P=0.006] and SVV [8 (95% CI 4-11) vs 13 (95% CI 11-15)%; P=0.004] were significantly different between non-responders and Rs. The areas under the receiver operating characteristic curves of SVi and SVV for predicting fluid responsiveness were 0.88 (95% CI 0.71-0.97) and 0.81 (95% CI 0.66-0.96), for a cut-off value of 29 ml m(-2) (grey zone 27-29 ml m(-2)) and 10% (grey zone 9-15%), respectively.

CONCLUSIONS

The results of this study show that SVi and SVV non-invasively measured by bioreactance are predictive of fluid responsiveness in sedated and mechanically ventilated children after surgery.

Fluid homeostasis in the neonate

The physiology of the neonate is ideally suited to the transition to extrauterine life followed by a period of rapid growth and development. Intravenous fluids and electrolytes should be prescribed with care in the neonate. Sodium and water requirements in the first few days of life are low and should be increased after the postnatal diuresis. Expansion of the extracellular fluid volume prior to the postnatal diuresis is associated with poor outcomes, particularly in preterm infants. Newborn infants are prone to hypoglycemia and require a source of intravenous glucose if enteral feeds are withheld. Anemia is common, and untreated is associated with poor outcomes. Liberal versus restrictive transfusion practices are controversial, but liberal transfusion practices (accompanied by measures to minimize donor exposure) may be associated with improved long-term outcomes. Intravenous crystalloids are as effective as albumin to treat hypotension, and semi-synthetic colloids cannot be recommended at this time. Inotropes should be used to treat hypotension unresponsive to intravenous fluid, ideally guided by assessment of perfusion rather than blood pressure alone. Noninvasive methods of assessing cardiac output have been validated in neonates. More studies are required to guide fluid management in neonates, particularly in those with sepsis or undergoing surgery. A balanced salt solution such as Hartmann's or Plasmalyte should be used to replace losses during surgery (and blood or coagulation factors as indicated). Excessive fluid administration during surgery should be avoided.

Plethysmographic variability index (PVI) accuracy in predicting fluid responsiveness in anesthetized children

INTRODUCTION

Plethysmographic Variability Index (PVI) has been shown to accurately predict responsiveness to fluid loads in adults. The goal of this study was to evaluate PVI accuracy when predicting fluid responsiveness during noncardiac surgery in children.

MATERIAL AND METHODS

Children aged 2-10 years scheduled for noncardiac surgery under general anesthesia were included. PVI was assessed concomitantly with stroke volume index (SVI). A response to fluid load was defined by an SVI increase of more than 15%. A 10 ml·kg(-1) normal saline intravenous fluid challenge was administered before surgical incision and after anesthetic induction. After incision, fluid challenges were administered when SVI values decreased by more than 15% or where judged necessary by the anesthesiologist. Statistical analyses include receiving operator characteristics (ROC) analysis and the determination of gray zone method with an error tolerance of 10%.

RESULTS

Fifty-four patients were included, 97 fluid challenges administered and 45 responses recorded. Area under the curve of ROC curves was 0.85 [0.77-0.93] and 0.8 [0.7-0.89] for baseline PVI and SVI values, respectively. Corresponding gray zone limits were [10-17%] and [22-31 ml·m(-2)], respectively. PVI values exhibited different gray zone limits for pre-incision and postincision fluid challenges, whereas SVI values were comparable. PVI value percentages in the gray zone were 34% overall and 44% for challenges performed after surgical incision.

DISCUSSION

This study found both PVI and prechallenge SVI to be accurate when used to predict fluid load response during anesthetized noncardiac surgery in children. However, a third of recorded PVI values were inconclusive.