G- Forces On Retrieved ChildrEn Pilot Study

Throughout the UK, paediatric transport services are responsible for the stabilisation and transport of critically unwell children. This involves moving children from district general hospitals to receive specialist care in tertiary centres and moving children between tertiary and quaternary centres in order to provide the appropriate level of specialist care.

Critically unwell children often require infusions of essential, life-saving medications during episodes of transport. Disruption of these infusions can be destabilising and even life-threatening. Examples of essential infusions include the use of prostin in duct-dependent congenital heart disease, vasoactive/inotropic medications in shock and sedation and muscle relaxants to ensure comfortable, safe transfer.

Critically unwell patients often require support in the form of inotropes/vasopressors to support cardiac contractility and alter vascular tone and are commonly used in the treatment of shock. Physiological response to vasoactive/inotropic drugs is rapid and measurable in terms of cardiovascular status through observing changes in heart rate, blood pressure and oxygenation of peripheral tissues (pulse oximetry). As such these medications offer the potential to observe whether syringe driver delivery variations as mediated through the effect of g-forces exert measurable physiological instability in transported patients.

G-Forces Pilot is a prospective, observational, case-control, feasibility study investigating the effect of G-forces as measured by an accelerometer against physiological parameters of heart rate, invasive blood pressure measurement and oxygen saturations in vivo during episodes of transport. The study aims to understand the relationship between the physics of transport on physiological parameters and to assess whether syringe driver delivery (previously demonstrated to be affected by G-forces in-vitro), is responsible for physiological variations in transported patients requiring vasoactive/inotropic infusions.

The investigators propose to examine this relationship by obtaining and analysing data on physiological parameters in patients during episodes of transport to assess:

(i) Whether G-forces experienced by being in a moving ambulance affect the stability of patient physiological parameters.

(ii) How variations in syringe driver delivery mediated through the effects of G-Forces affect patients in transit as evidenced through instability in physiological parameters whilst receiving vasoactive/inotropic infusions.

This will be examined by the comparison of a control and study group. The control group will consist of patients with full monitoring (including an arterial line), without vasoactive/inotropic support. The study group will consist of patients with full monitoring (including an arterial line) receiving vasoactive/inotropic support through a syringe driver. Data analysis will assess the strength of correlation between patient observations and experienced g-forces recorded during the episode of transport to answer the study question.

Inclusion criteria

(i) Any child, 36 weeks corrected gestation to 18 years, accepted for transport by the COMET retrieval service who has an arterial line with active arterial blood pressure monitoring at departure from the referring hospital. The decision for the need for an arterial line is determined purely on a clinical basis by the referring, transporting or accepting clinical team.

Exclusion criteria

(i) Children outside the specified age range.

(ii) Children who do not have invasive arterial blood pressure monitoring during a transport episode.

(iii) Any case where patients, parents or guardians elect to opt out of data analysis.