EL DISCURS DEL PROFESSIONAL: LES APORTACIONS DE DONALD FREEMAN.

This study aimed to answer the question of “do speed and road conditions have an effect on the stability of sick and preterm babies undergoing inter-hospital transfer by ambulance?” With due regard to the restrictions imposed by the limits of incomplete, incompatible datasets and the consequent basing of findings for this thesis on analysis of complete datasets from seven cases, at this point a number of tentative outcomes can be reported. These require confirmation, and this may be possible with deeper, more complex analysis of the remaining large amount of data as a post-doctoral effort. Support from the equipment manufacturers will be required to harness the currently inaccessible data and to harmonise the conflicting physiological and environmental datasets.

i. Does the baby’s gestation have any impact on the physiological stability? The neonates overall stability could be influenced by the gestation with the extreme preterm being more susceptible to swings in heart rate and blood pressure. Within this study, however, the most preterm neonate (Case 4) was transferred at 42 days of age and was more unstable due to his disease pathology rather than because of his gestation. Case 9 involved the baby who was transferred at the earliest gestation on the first day of life, but this was not the most unstable neonate in the study.

ii. Is it the speed, acceleration or deceleration (x axis), that has the greatest consequence on physiological instability?

The strongest finding of this study related to speed. From the neonates included in this study it was not the actual speed of mph that could be correlated with any physiological instability. It was discovered that constant speed was the factor most concerned with stability. Even those neonates that exhibited signs of stress at the beginning of the journey started to stabilise when speed became a constant (Cases 9 and 10). Acceleration and deceleration appeared to have some impact on some of the neonates, but from the limited numbers it was not possible to state a definitive finding.

iii. Do the road conditions, roundabouts and cornering (y axis) or road surface, bumps, pot holes, vibrations (z axis) have any impact on the physiological stability?

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Road conditions that involved smoother surfaces and prevented changes in speed due to acceleration and deceleration were positively associated with the neonate’s stability. However, finer aspects of this require further consideration. Additional analysis of more cases may allow distinction between the effects of lateral forces (cornering and roundabouts) and vertical forces (vibration, speed bumps).

iv. Does the difference covered have any effect on the overall results?

In this study there was no correlation with the distance of the journey and instability in physiological variables. The heart rate trend increases in some patients (Cases 2,5,9,10) however it is not dependent on gestation or length of journey.

v. Does the model of ambulance used (z axis) have any influence on physiological stability?

There were three different models of ambulance used in this study. The dedicated vehicle SM301 was used in 7 of the journeys with the Mercedes being used in 3 journeys and no data about vehicle type in one case. There was no correlation between cases that showed a positive outcome for one vehicle rather than another.

vi. Is one physiological sign affected more than any other?

Saturations readings are more susceptible to artefact interference in the transport setting than some of the other physiological parameters so it is advised that they are not used in isolation. However the saturations are one of the first parameters to signify a change in clinical condition. Heart rate and arterial blood pressure give a more reliable indication when used in conjunction with other parameters and are less inclined to be affected by artefacts in the transport setting. There was no clear indication that motorway travel, length of journey or increased speeds affects arterial blood pressure recordings.

vii. Does the disease or treatment have an impact on how the neonate tolerates the transfer process?

The disease process appears to exert an impact on how the neonate tolerates the transfer process. Any disease process that impacts on the cardio vascular system has the potential to worsen during the transport episode (Cases 3 and 8). In the selected cases in this study, stability was found not to be related to size or gestation. Some of the sicker neonates were bigger term infants. More cases would be needed to establish

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these distinctions with confidence. Treatment options such as sedation and paralysis also impact on how the neonate reacts to the environment and can mask or delay responses, giving the impression that they are clinically stable. This aspect of hidden instability requires further investigation.

Conclusion

The findings confirmed that some neonates in this study were negatively affected clinically by the transport experience. Although limited in number of cases, the sample was diverse in relation to gestation, age, underlying pathology and clinical diagnosis which empowered the findings to challenge previous beliefs that it was only the smallest most fragile neonates that were the most susceptible to transport stresses. Neonates previously thought to have tolerated a transport without any effect have been shown to display more subtle changes related to stress responses that are not initially obvious. Some of the neonates were affected more by transport than others due to the many confounding variables involved, but this study has indicated which variables might be controlled in order to limit destabilisation. The study provided new knowledge about the impact of speed on individual neonates, highlighting that speed of itself may not be the destabilising factor. The study has raised further questions regarding the positioning of the equipment and the neonate, ambulance type, and advantages of dedicated drivers. It has been difficult previously to predict which neonates are more likely to suffer adverse reactions, but this study has added to the limited knowledge base linking disease pathology with increased risk of instability or deterioration in the transport setting. These findings will be discussed in more detail in Chapter 6.

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CHAPTER 6: DISCUSSION