Background

Early detection of left ventricular (LV) failure is crucial to improve prognosis of patients with right ventricular (RV) overload.

Objectives

We aim to assess whether LV function is precociously affected in 2 surgical porcine models of moderate (Fallot repaired) and severe RV dysfunction (progressive pulmonary hypertension HP) at in vivo and in vitro levels.

Methods

3 animals of each surgical group were compared with 6 controls/Sham. 4 months after surgeries, LV function was evaluated using echocardiography/strain compared with conductance catheter. At cellular level using isolated cardiomyocytes, calcium transients amplitude with relaxation time associated and sarcomere shortening were recorded using Ionoptix system. T-tubules network integrity (DI-4-ANEPPS) and colocalization (Immunofluorescence) between main Excitation/Contraction (EC) actors (Ca^2+v1.2-Ryr) were analyzed. Contractile reserve was evaluated by adrenergic stimulation in-vivo and in-vitro (Dobutamine-isoproterenol).

Results

Despite RV dysfunctions in both groups, LV present hemodynamic impairment only in HP group (Longitudinal strain 9 versus 18%. Conductance catether with dobutamin: Elastance arterial 7.7 versus 1,32, SV 14 versus 75ml and tau (relaxation) 49 versus 27, p<0.05).In cardiomyocytes, we observe decrease of Ca²⁺ transient amplitude and cardiomyocytes contraction, acceleration of Ca²⁺ relaxation time, T-tubule network desorganisation and Cav1.2/Ryr decoupling(fig1). In vivo and in vitro, adrenergic stimulations increase dysfunction.

Conclusion

In vitro experiments pointed early abnormalities in LV EC particularly after adrenergic stimulation. A better understanding of cellular alterations could lead to survival improvement.

Background

Mortality is modelled as a quadratic function of systolic blood pressure (SBP) at admission to PICU in the Paediatric Index of Mortality score (PIM). The lowest risk of mortality is at 120 mmHg, regardless of age (1). As most children on PICU, are under 2 years of age, this is the >99^th centile.

Objectives

We sought to define the association between age-corrected SBP z-scores and mortality in critically ill children.

Methods

In this retrospective cohort study, we gathered SBP values on admission to four paediatric intensive care units (2 cardiac and 2 general) in 34,745 children from 2004-2018. We derived SBP z-scores according to the NIH Task Force definitions of normal SBP. We defined the relationship between mortality and SBP z-scores using logistic regression, adjusted for PIM-2 with the blood pressure component removed.

Results

The relationship in our cohort showed a U-shaped curve with a nadir at SBP between 111-120, or 2.25<=z<2.75 (Fig.1), though mortality was found to be relatively invariant over a wide range of SBP values (increasing only from bands 1.25<=z<1.75 and >=3.25) with narrow confidence intervals.

Conclusion

Our data support the value of using SBP z-scores rather than absolute values in children. Prospective trials examining the impact of different blood pressure targets on mortality in critically ill children are needed.

References:

(1) Shann F, Pearson G, Slater A, Wilkinson k. Paediatric index of mortality (PIM): a mortality prediction model for children in intensive care. ICM. 1997. 23:201-207.

Background

The relationship between temperature and heart rate (HR) has been described as non-linear, with HR increasing by ~ 10 beats/min for every 1°C rise in body temperature. Previous studies have excluded critically ill children.

Objectives

We sought to delineate this relationship in the PICU population using high-frequency bedside monitoring data.

Methods

This is a retrospective observational study using the Etiometry T3 recording system of 142 children with continuous central temperature monitoring admitted to the PICU/NICU at Great Ormond Street Hospital in 2016. HR data were standardised to provide z-scores. Multi-level linear regression analysis of 7,393,328 HR measurements was done for 1°C intervals between 36-40°C.

Results

The regression coefficient for temperature was 8.314 (95% CI 8.299-8.329). The relationship between temperature and HR was non-linear, with the greatest change between 38-39°C, with HR increasing by 20 beats/min (Figure 1). The relationship remained unchanged when analysis was repeated using age-standardised HR.

Conclusion

The relationship between HR and temperature is non-linear in critically ill children. Fever grade (≥38°C) temperature is associated with a significant increase in HR. Further studies are needed to understand the impact of the raised heart rate on haemodynamics in critically ill children

Background

Conventional echocardiography remains the gold standard for non-invasive evaluation of cardiac function including cardiac output (CO) monitoring at the bed site in neonates. Because of the accuracy it could be performed by paediatric cardiologist or specially trained and experienced neonatologist. Continuous-wave Doppler ultrasound monitor (USCOM) is a relatively new monitor for cardiac function measurement, but it is faster and less complex to train new users than conventional echocardiography. Data comparing these two methods in the neonatal population is limited.

Objectives

To assess the level of agreement between CO measured with conventional echocardiography and with USCOM.

Methods

Hemodynamically stable, various gestational age neonates with normal heart anatomy, absence of infection and no need of any respiratory support were included into prospective, observational study carried out at Neonatal Centre of Vilnius University.
Functional echocardiography and subsequent USCOM study for comparison of CO was performed by trained neonatologist.

Results

The study enrolled 100 neonates. Data collected shows a very strong correlation between CO as measured by echocardiography and by USCOM. The mean difference in CO is -87ml min-1 (SD 150ml min-1). Bland-Altman analysis confirmed no significant bias with acceptable limits of agreement between these two methods.

Conclusion

CO measured using USCOM correlated well with echocardiographic measurement. Thus, USCOM as alternative to conventional echocardiography could be more simple and valuable tool for evaluation of neonatal cardiac performance.