Aspects of pediatric hemodynamics. A study of young children undergoing corrective heart surgery.

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Abstract

Background: Assessing critically ill patients is demanding because their clinical signs are not always easy to interpret. This is particularly true for pediatric patients, due to their small size and robust circulatory compensatory
mechanism. Physicians working in pediatric intensive care settings seldom use invasive monitoring, due to possible complications and the risks involved. Instead, they rely on simple vital parameters and blood gases during their clinical work. However, a number of studies have shown that this clinical approach can provide inaccurate data when dealing with critically ill patients. There are very few monitors currently available that have been fully validated for estimating hemodynamic parameters in young children. A less invasive hemodynamic monitor could help physicians make clinical decisions and improve future levels of care, by providing more reliable information on the perioperative hemodynamic status of pediatric patients, without additional risks.

Purpose: The primary aim of the studies in this thesis was to look at different aspects of pediatric hemodynamics, by comparing the novel hemodynamic COstatus monitor, with earlier reference methods.

In our studies we analyzed:
1) aggrement and precision of cardiac output, 2) detection and estimation of of intracardiac shunts and 3) estimation of different blood volumes. A secondary aim of this thesis was to establish reference values of hemodynamic values in young children using COstatus, and comparing idexing of same values with body surface area and body weight.

Methods: Children (under 15 kilograms) undergoing corrective heart surgery at Lund Children´s Hospital were enrolled in our studies.

Results:

Paper I – Estimation of cardiac output
The COstatus provided excellent precision and agreement in estimating cardiac output in young children, compared with perivascular flow probe placed around the ascending aorta.

Paper II – Estimation of intracardiac shunts.
The COstatus detected intracardiac shunts to the same extent as the “gold standard” echocardiography. However, it slightly underestimated the degrees of the shunts in small and moderate shunts when it was compared to two other reference methods, namely perivascular ultrasonic flow probes (placed around the pulmonary truncus and ascending aorta) and the oximetric shunt equation (using arterial and venous blood gases).

Paper III – Normalization of hemodynamic parameters.
Body weight produced a better normalization of hemodynamic parameters than body surface area in young children.

Paper IV – Estimation of oxygen uptake.
Indirect calorimetry seemed to overestimate oxygen uptake in young
children, compared to the reverse Fick method.

Paper V – Estimation of body surface area.
Commonly used body surface area formulas disagreed in young
children, Mosteller formula came closest to the mean body surface area.

Conclusions: COstatus is accurate, precise and less invasive than earlier reference methods and might enable future cardiac output comparison studies in the intensive care setting. COstatus detects shunts accurately but algorithms for shunt size estimations might be overly cautious. Caution is advised regarding the use of indirect calorimetry and direct Fick method in cardiac output comparison studies.

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Anesthesiology and Intensive Care

Keywords

  • Cardiac output, Heart surgery, Hemodynamics, Intracardiac shunt, Volume estimation, Young children
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
  • Lars Lindberg, Supervisor
  • Valéria Perez de Sá, Assistant supervisor
Award date2020 Oct 2
Place of PublicationLund
Publisher
  • Lund University, Faculty of Medicine
Print ISBNs978-91-7619-977-0
Publication statusPublished - 2020
Publication categoryResearch

Bibliographic note

Defence details Date: 2020-10-02 Time: 13:00 Place: Föreläsningssal 2, Centralblocket, Entrégatan 7, Skånes Universitetssjukhus i Lund External reviewer(s) Name: de Boode, Willem-Pieter Title: Professor Affiliation: Department of Neonatology, Radboud University Nijmegen Medical Centre, Nijmegen

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