Variability in the Hemodynamic Response to Fluid Bolus in Pediatric Septic Shock

Accuracy of Respiratory Variation in Inferior Vena Cava Diameter to Predict Fluid Responsiveness in Children Under Mechanical Ventilation

Proper assessment of fluid responsiveness using accurate predictors is crucial to guide fluid therapy and avoid the serious adverse effects of fluid overload. The main objective of this study was to investigate the accuracy of respiratory variations in inferior vena cava diameter (∆IVC) to predict fluid responsiveness in mechanically ventilated children. This prospective single-center study included 32 children (median age and weight of 17 months and 10 kg, respectively) who received a fluid infusion of 10 ml kg-1 of crystalloid solutions over 10 min. ∆IVC and respiratory variation in aortic blood flow peak velocity (∆Vpeak) were determined over one controlled respiratory cycle before and after fluid loading. Thirteen (41%) participants were fluid-responders. ∆IVC, ∆Vpeak, stroke volume index, and cardiac index were found to be predictors of fluid responsiveness. However, the area under the ROC curve of ∆IVC was smaller when compared to ∆Vpeak (0.709 vs. 0.935, p < 0.012). The best cut-off values were 7.7% for ∆IVC (sensitivity, 69.2%; specificity 78.9%, positive predictive value, 69.2%; and negative predictive value, 78.9%) and 18.2% for ∆Vpeak (sensitivity, 84.6%; specificity, 89.5%; positive predictive value, 84.6%; negative predictive value, 89.5%). Changes in stroke volume were positively correlated with ∆IVC (ρ = 0.566, p < 0.001) and ∆Vpeak (ρ = 0.603, p < 0.001). A significant correlation was also found between changes in MAP and ∆Vpeak (ρ = 0.382; p = 0.031), but the same was not observed with ∆IVC (ρ = 0.011; p = 0.951). In conclusion, ∆IVC was found to have a moderate accuracy in predicting fluid responsiveness in mechanically ventilated children and is an inferior predictor when compared to ∆Vpeak.

Management Changes After Echocardiography Are Associated With Improved Outcomes in Critically Ill Children

OBJECTIVES

To evaluate management changes and outcomes in critically ill children after formal echocardiography.

DESIGN

Retrospective cohort study between January 1, 2011, and December 31, 2020.

SETTING

Tertiary care children's hospital.

PATIENTS

Patients from 1 to 18 years who had formal echocardiography within 72 hours of ICU admission and who were intubated and on vasoactive infusions at the time of the study. Patients were stratified into two cardiac function groups: 1) near-normal cardiac function and 2) depressed cardiac function.

METHODS

Clinical variables were abstracted from the electronic medical record and placed in time sequence relative to echocardiography. Vasoactive and fluid management strategies in place before echocardiography were associated with markers of tissue perfusion and volume overload. Management changes after echocardiography were characterized and associated with outcomes.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among patients eventually found to have depressed cardiac function, the use of vasoconstrictors was associated with worse lactate clearance and oxygen extraction ratio. Use of vasoconstrictors in this cohort was also associated with a more liberal fluid management strategy, evidence of increased lung water, and a worse Sp o2 /F io2 . An echocardiogram demonstrated depressed cardiac function was likely to be followed by management changes that favored inotropes and more conservative fluid administration. Patients with depressed cardiac function who were switched to inotropes were more likely to be extubated and to wean off vasoactive support compared with those patients who remained on vasoconstrictors.

CONCLUSIONS

Among patients with depressed cardiac function, alterations in management strategy after echocardiography are associated with shortened duration of intensive care interventions.

Resuscitation With Early Adrenaline Infusion for Children With Septic Shock: A Randomized Pilot Trial

OBJECTIVES

In children with septic shock, guidelines recommend resuscitation with 40-60 mL/kg of fluid boluses, yet there is a lack of evidence to support this practice. We aimed to determine the feasibility of a randomized trial comparing early adrenaline infusion with standard fluid resuscitation in children with septic shock.

DESIGN

Open-label parallel randomized controlled, multicenter pilot study. The primary end point was feasibility; the exploratory clinical endpoint was survival free of organ dysfunction by 28 days.

SETTING

Four pediatric Emergency Departments in Queensland, Australia.

PATIENTS

Children between 28 days and 18 years old with septic shock.

INTERVENTIONS

Patients were assigned 1:1 to receive a continuous adrenaline infusion after 20 mL/kg fluid bolus resuscitation (n = 17), or standard care fluid resuscitation defined as delivery of 40 to 60 mL/kg fluid bolus resuscitation prior to inotrope commencement (n = 23).

MEASUREMENTS AND MAIN RESULTS

Forty of 58 eligible patients (69%) were consented with a median age of 3.7 years (interquartile range [IQR], 0.9-12.1 yr). The median time from randomization to inotropes was 16 minutes (IQR, 12-26 min) in the intervention group, and 49 minutes (IQR, 29-63 min) in the standard care group. The median amount of fluid delivered during the first 24 hours was 0 mL/kg (IQR, 0-10.0 mL/kg) in the intervention group, and 20.0 mL/kg (14.6-28.6 mL/kg) in the standard group (difference, -20.0; 95% CI, -28.0 to -12.0). The number of days alive and free of organ dysfunction did not differ between the intervention and standard care groups, with a median of 27 days (IQR, 26-27 d) versus 26 days (IQR, 25-27 d). There were no adverse events reported associated with the intervention.

CONCLUSIONS

In children with septic shock, a protocol comparing early administration of adrenaline versus standard care achieved separation between the study arms in relation to inotrope and fluid bolus use.

Cardiac output monitoring in children: a review

Cardiac output monitoring enables physiology-directed management of critically ill children and aids in the early detection of clinical deterioration. Multiple invasive techniques have been developed and have demonstrated ability to improve clinical outcomes. However, all require invasive arterial or venous catheters, with associated risks of infection, thrombosis and vascular injury. Non-invasive monitoring of cardiac output and fluid responsiveness in infants and children is an active area of interest and several proven techniques are available. Novel non-invasive cardiac output monitors offer a promising alternative to echocardiography and have proven their ability to influence clinical practice. Assessment of perfusion remains a challenge; however, technologies such as near-infrared spectroscopy and photoplethysmography may prove valuable clinical adjuncts in the future.

Haemodynamic support for paediatric septic shock: a global perspective

Septic shock is a leading cause of hospitalisation, morbidity, and mortality for children worldwide. In 2020, the paediatric Surviving Sepsis Campaign (SSC) issued evidence-based recommendations for clinicians caring for children with septic shock and sepsis-associated organ dysfunction based on the evidence available at the time. There are now more trials from multiple settings, including low-income and middle-income countries (LMICs), addressing optimal fluid choice and amount, selection and timing of vasoactive infusions, and optimal monitoring and therapeutic endpoints. In response to developments in adult critical care to trial personalised haemodynamic management algorithms, it is timely to critically reassess the current state of applying SSC guidelines in LMIC settings. In this Viewpoint, we briefly outline the challenges to improve sepsis care in LMICs and then discuss three key concepts that are relevant to management of children with septic shock around the world, especially in LMICs. These concepts include uncertainties surrounding the early recognition of paediatric septic shock, choices for initial haemodynamic support, and titration of ongoing resuscitation to therapeutic endpoints. Specifically, given the evolving understanding of clinical phenotypes, we focus on the controversies surrounding the concepts of early fluid resuscitation and vasoactive agent use, including insights gained from experience in LMICs and high-income countries. We outline the key components of sepsis management that are both globally relevant and translatable to low-resource settings, with a view to open the conversation to the large variety of treatment pathways, especially in LMICs. We emphasise the role of simple and easily available monitoring tools to apply the SSC guidelines and to tailor individualised support to the patient's cardiovascular physiology.

Fluid bolus therapy in pediatric sepsis: a narrative review

Leading cause of death in children under five, pediatric sepsis remains a significant global health threat. The 2020 Surviving Sepsis Campaign guidelines revised the management of septic shock and sepsis-associated organ dysfunction in children. In addition to empiric broad-spectrum antibiotics, fluid bolus therapy is one of the cornerstones of management, due to theoretical improvement of cardiac output, oxygen delivery and organ perfusion. Despite a very low level of evidence, the possible benefit of balanced crystalloids in sepsis resuscitation has led to discussion on their position as the ideal fluid. However, the latest adult data are not consistent with this, and the debate is still ongoing in pediatrics. We provide here the current state of knowledge on fluid bolus therapy in pediatric sepsis with emphasis on balanced crystalloids.

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.

Carotid doppler ultrasonography as a method to predict fluid responsiveness in mechanically ventilated children

AIMS

The aim of this study was to investigate whether respiratory variations in carotid and aortic blood flows measured by Doppler ultrasonography could accurately predict fluid responsiveness in critically ill children.

METHODS

This was a prospective single-center study including mechanically ventilated children who underwent fluid replacement at the discretion of the attending physician. Response to fluid load was defined by a stroke volume increase of more than 15%. Maximum and minimum values of velocity peaks were determined over one controlled respiratory cycle before and after volume expansion. Respiratory changes in velocity peak of the carotid (∆Vpeak_Ca) and aortic (∆Vpeak_Ao) blood flows were calculated as the difference between the maximum and minimum values divided by the mean of the two values and were expressed as a percentage.

RESULTS

A total of 30 patients were included, of which twelve (40%) were fluid responders and 18 (60%) non-responders. Before volume expansion, both ∆Vpeak_Ca and ∆Vpeak_Ao were higher in responders than in non-responders (17.1% vs 4.4%; p < .001 and 22.8% vs 6.4%; p < .001, respectively). ∆Vpeak_Ca could effectively predict fluid responsiveness (AUC 1.00, 95% CI 0.88-1.00), as well as ∆Vpeak_Ao (AUC 0.94, 95% CI 0.80-0.99). The best cutoff values were 10.6% for ∆Vpeak_Ca (sensitivity, specificity, positive predictive value and negative predictive value of 100%) and 18.2% for ∆Vpeak_Ao (sensitivity, 91.7%; specificity, 88.9%; positive predictive value, 84.6%; negative predictive value, 94.1%). Volume expansion-induced changes in stroke volume correlated with the ∆Vpeak_Ca and ∆Vpeak_Ao before volume expansion (ρ of 0.70 and 0.61, respectively; p < .001 for both).

CONCLUSIONS

Analysis of respiratory changes in carotid and aortic blood flows are accurate methods for predicting fluid responsiveness in children under invasive mechanical ventilation.

BESTFIT-T3: A Tiered Monitoring Approach to Persistent/Recurrent Paediatric Septic Shock - A Pilot Conceptual Report

Objective

Persistent shock (PS) or recurrent shock (RS) after initial fluids and vasoactives can be secondary to myriad complex mechanisms, and these patients can have a high mortality. We developed a noninvasive tiered hemodynamic monitoring approach which included, in addition to basic echocardiography, cardiac output monitoring and advanced Doppler studies to determine the etiology and provide targeted therapy of PS/RS.

Design

Prospective observational study.

Setting

Tertiary Care Pediatric Intensive Care Unit, India.

Methods

A pilot conceptual report describing the clinical presentation of 10 children with PS/RS using advanced ultrasound and noninvasive cardiac output monitoring. Children with PS/RS after initial fluids and vasoactive agents despite basic echocardiography underwent BESTFIT + T3 (Basic Echocardiography in Shock Therapy for Fluid and Inotrope Titration) with lung ultrasound and advanced 3-tiered monitoring (T1-3).

Results

Among 10/53 children with septic shock and PS/RS over a 24-month study period, BESTFIT + T3 revealed combinations of right ventricular dysfunction, diastolic dysfunction (DD), altered vascular tone, and venous congestion (VC). By integrating information obtained by BESTFIT + T1-3 and the clinical context, we were able to modify the therapeutic regimen and successfully reverse shock in 8/10 patients.

Conclusion

We present our pilot results with BESTFIT + T3, a novel approach that can noninvasively interrogate major cardiac, arterial, and venous systems that may be particularly useful in regions where expensive rescue therapies are out of reach. We suggest that, with practice, intensivists already experienced in bedside POCUS can use the information obtained by BESTFIT + T3 to direct time-sensitive precision cardiovascular therapy in persistent/recurrent pediatric septic shock.

How to cite this article

Natraj R, Ranjit S. BESTFIT-T3: A Tiered Monitoring Approach to Persistent/Recurrent Paediatric Septic Shock - A Pilot Conceptual Report. Indian J Crit Care Med 2022;26(7):863-870.