Sound and vibration: effects on infants' heart rate and heart rate variability during neonatal transport

Neonatal Transport Safety Metrics and Adverse Event Reporting: A Systematic Review

OBJECTIVE

Neonatal transports are an essential component of regionalized medical systems. Neonates who are unstable after birth require transport to a higher level of care by neonatal transport teams. Data on adverse events on neonatal transports are limited. The aim of this study was to identify, evaluate, and summarize the findings of all relevant studies on adverse events on neonatal transports.

METHODS

We identified 38 studies reporting adverse events on neonatal transports from January 1, 2000, to December 31, 2019. The adverse events were distributed into 5 categories: vital sign abnormalities, laboratory value abnormalities, equipment challenges, system challenges, cardiopulmonary resuscitation, and transport-related mortality.

RESULTS

Most of the evidence surrounds vital sign abnormalities during transport (n = 28 studies), with hypothermia as the most frequently reported abnormal vital sign. Fourteen studies addressed laboratory abnormalities, 12 reported on events related to equipment issues, and 4 reported on system issues that lead to adverse events on transport. Of the 38 included studies, 12 included mortality related to transport as an outcome, and 4 reported on cardiopulmonary resuscitation during transport. There were significant variations in samples, definitions of adverse events, and research quality.

CONCLUSION

Adverse events during neonatal transport have been illuminated in various ways, with vital sign abnormalities most commonly explored in the literature. However, considerable variation in studies limits a clear understanding of the relative frequencies of each type of adverse event. The transport safety field would benefit from more efforts to standardize adverse event definitions, collect safety data prospectively, and pool data across larger care systems.

Effects of whole-body vibration on driver drowsiness: A review

INTRODUCTION

Whole-body vibration has direct impacts on driver vigilance by increasing physical and cognitive stress on the driver, which leads to drowsiness, fatigue and road traffic accidents. Although sleep deprivation, sleep apnoea and alcohol consumption can also lead to driver drowsiness, exposure to steady vibration is the factor most readily controlled by changes to vehicle design, yet it has received comparatively less attention.

METHODS

This review investigated interrelationships between the various components of whole-body vibration and the physiological and cognitive parameters that lead to driver drowsiness, as well as the effects of vibration parameters (frequency, amplitude, waveform and duration). Vibrations transmitted to the driver body from the vehicle floor and/or seat have been considered for this review, whereas hand-arm vibration, shocks, acute or transient vibration were excluded from consideration.

RESULTS

Drowsiness is affected by interactions between the frequency, amplitude, waveform and duration of the vibration. Under optimal conditions, whole-body vibration can induce significant drowsiness within 30 min. Low frequency whole-body vibrations, particularly vibrations of 4-10 Hz, are most effective at inducing drowsiness. This review notes some limitations of current studies and suggests directions for future research.

CONCLUSIONS

This review demonstrated a strong causal link exists between whole-body vibration and driver drowsiness. Since driver drowsiness has been established to be a significant contributor to motor vehicle accidents, research is needed to identify ways to minimise the components of whole-body vibration that contribute to drowsiness, as well as devising more effective ways to counteract drowsiness.

PRACTICAL APPLICATIONS

By raising awareness of the vibrational factors that contribute to drowsiness, manufacturers will be prompted to design vehicles that reduce the influence of these factors.

Experience of Mass Intrahospital Neonatal Transport: Impact on Vitals

Background

Mass transport of neonates is required in cases of disasters and calamities such as fire. It may also be required when there is a need for the upgradation of infrastructure. Neonatal transport even for a short period is a period of stress for the neonate. Mass transport of neonates needs much planning, and even after diligent planning, may result in the destabilization of neonates.

Objectives

The objectives of this study were to assess the impact of mass intrahospital neonatal transport on the vital parameters of neonates, the occurrence of any adverse event during transport. To study the frequency of adverse events in mass intrahospital neonatal transport and factors related to it.

Materials and methods

This was a retrospective observational study on a cohort of 16 neonates who were transported to an alternate site in the hospital so that renovation and upscaling of the infrastructure of the newborn intensive care unit (NICU) could be undertaken. Site selection, preparation, and transport details were observed. Vital parameters pre and post-transport were noted, and the occurrence of adverse events during transport was documented and analyzed.

Results

Sixteen neonates were transported over a span of 90 minutes with a mean travel time of 5.62±3.03 minutes. There was a statistically significant rise in the heart rate of the neonates post transport (137.7±8.51vs 141.3±9.01, p-value .00769) though not clinically significant. Six point two-five percent (6.25%) of neonates deteriorated post transport and needed extra efforts for stabilization. Equipment malfunction was responsible for deterioration.

Conclusion

Unforeseen events can occur during neonatal transport. Despite adequate planning, preparation, and care during transport, it remains a period of stress for a neonate.

Temporal trends of in utero and early postnatal transfer of extremely preterm infants between 2011 and 2016: a UK population study

OBJECTIVE

Early postnatal transfer (PNT) of extremely preterm infants is associated with adverse outcomes compared with in utero transfer (IUT). We aimed to explore recent national trends of IUT and early PNT.

DESIGN

Observational cohort study using the National Neonatal Research Database.

SETTING

Neonatal units in England, Scotland and Wales.

PATIENTS

Extremely preterm infants 23⁺⁰-27⁺⁶ weeks' gestation admitted for neonatal care from 2011 to 2016.

MAIN OUTCOME

The incidence of IUT or PNT within 72 hours of life. Secondary outcomes included mortality, hospital transfer level between centres and temporal changes across two equal epochs, 2011-2013 (epoch 1 (Ep1)) and 2014-2016 (epoch 2 (Ep2)).

RESULTS

14 719 infants were included (Ep1=7363 and Ep2=7256); 4005 (27%) underwent IUT; and 3042 (20.7%) had PNT. IUTs decreased significantly between epochs from 28.3% (Ep1=2089) to 26.0% (Ep2=1916) (OR 0.90, 95% CI 0.84 to 0.97, p<0.01). Conversely, PNTs increased from 19.8% (Ep1=1416) to 21.5% (Ep2=1581) (OR 1.11, 95% CI 1.02 to 1.20, p=0.01). PNTs between intensive care centres increased from 8.1% (Ep1=119) to 10.2% (Ep2=161, p=0.05). Mortality decreased from 21.6% (Ep1=1592) to 19.3% (Ep2=1421) (OR 0.90, 95% CI 0.83 to 0.97, p=0.01). Survival to 90 days of age was significantly lower in infants undergoing PNT compared with IUT (HR 1.31, 95% CI 1.18 to 1.46), with the greatest differences observed in infants <25 weeks' gestational age.

CONCLUSION

In the UK, IUT of extremely preterm infants has significantly decreased over the study period with a parallel increase in early PNT. Strategies to reverse these trends, improve IUT pathways and optimise antenatal steroid use could significantly improve survival and reduce brain injury for these high-risk infants.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

CONFIRMATION OF THE CLINICAL VALUE AND THE EFFECT OF SOUND BIOFEEDBACK ON THE AUTONOMIC NERVOUS SYSTEM THROUGH HEART RATE VARIABILITY ANALYSIS

The purpose of this study is to suggest sound biofeedback, which is a new technique of early stress relief effect by observing change in the heart rate variability (HRV). The sound biofeedback imitating heart rate of the comfortable and stress state is termed parasympathetic stimulation sound (PSS) and sympathetic stimulation sound (SSS), respectively. Twelve subjects were selected without previous history of cardiovascular diseases and mental illness, such as arrhythmia, myocardial infarction, depression and panic disorder. To confirm the changes in the low-frequency (LF), high-frequency (HF) and LF/HF values of HRV as stress evaluation indicators, the HRV of subjects was measured by photoplethysmogram. Signals were processed using the peak detect algorithm, and fast Fourier transform. Results were obtained using power specific densities. During the PSS stimulation, the LF/HF tended to decrease generally. On the other hand, during the SSS stimulation, LF/HF tended to increase. The LF/HF Mean change value ([Formula: see text]) using the PSS stimulation is similar to the effect of Transcutaneous Vagal Nerve Stimulation (tVNS). In addition, the quantitative effect of sound biofeedback was confirmed by judging changes in the parasympathetic and sympathetic nerves in the autonomic nervous system (ANS) through [Formula: see text]-score normalized data. These experimental results suggest that sound biofeedback has the same stimulation location and clinical applicability as tVNS. As a result, sound biofeedback may be used as a new method for stress reduction.

Smartphone monitoring of in-ambulance vibration and noise

Transferring sick premature infants between hospitals increases the risk of severe brain injury, potentially linked to the excessive exposure to noise, vibration and driving-related accelerations. One method of reducing these levels may be to travel along smoother and quieter roads at an optimal speed, however this requires mass data on the effect of roads on the environment within ambulances. An app for the Android operating system has been developed for the purpose of recording vibration, noise levels, location and speed data during ambulance journeys. Smartphone accelerometers were calibrated using sinusoidal excitation and the microphones using calibrated pink noise. Four smartphones were provided to the local neonatal transport team and mounted on their neonatal transport systems to collect data. Repeatability of app recordings was assessed by comparing 37 journeys, made during the study period, along an 8.5 km single carriageway. The smartphones were found to have an accelerometer accurate to 5% up to 55 Hz and microphone accurate to 0.8 dB up to 80 dB. Use of the app was readily adopted by the neonatal transport team, recording more than 97,000 km of journeys in 1 year. To enable comparison between journeys, the 8.5 km route was split into 10 m segments. Interquartile ranges for vehicle speed, vertical acceleration and maximum noise level were consistent across all segments (within 0.99 m . s^-1, 0.13 m · s^-2 and 1.4 dB, respectively). Vertical accelerations registered were representative of the road surface. Noise levels correlated with vehicle speed. Android smartphones are a viable method of accurate mass data collection for this application. We now propose to utilise this approach to reduce potential harmful exposure, from vibration and noise, by routing ambulances along the most comfortable roads.

Finding Comfortable Routes for Ambulance Transfers of Newborn Infants

Early inter-hospital ambulance transport of premature babies is associated with more severe brain injury. The mechanism is unclear, but they are exposed to excessive noise and vibration. Smart-routing may help minimise these exposure levels and potentially improve outcomes.An app for Android smartphones was developed to collect vibration, noise and location data during ambulance journeys. Four smartphones, with the app installed, were provided to the local neonatal transport group to attach to their incubator trolleys. An example of route comparison was performed on the roads used between Nottingham City Hospital (NCH) and Leicester Royal Infirmary (LRI).Almost 1,700 journeys were recorded over the space of a year. 39 of these journeys travelled from NCH to LRI, comprising of 9 different routes. Analysis was performed on all recorded data which travelled along each road. For routes from NCH to LRI, the route with least vibration was also the quickest. Noise levels, however, were found to increase with vehicle speed. Ambulance drivers in the study did not tend to take the quickest, smoothest or quietest route.Android smartphones are a practical method of gathering information about the in-ambulance environment. Routes were found to vary in vibration, noise and speed, suggesting these could be minimised. The next step is to combine recorded and clinical data to try and define an ideal neonatal comfort metric which can then be fed into the routing. Roll-out of the app around the UK is also planned.Clinical relevance-Transferring preterm neonatal infants to specialist units lead to worse outcomes. By reducing the levels of vibration and noise the infants are exposed to during transport, we hope to improve outcomes.

NeoSTRESS: Study of Transfer and Retrieval Environmental StressorS upon neonates via a smartphone application - Sound

AIM

This study aimed to measure sound exposure during neonatal retrieval, determine whether this varied with mode of transport, and compare noise exposure to recommended levels in neonatal intensive care units. We also aimed to assess the acceptability of using a smartphone application to measure sound.

SETTING

Neonatal retrieval service in Brisbane, Australia.

METHODS

The Physics Toolbox Sensor Suite application was installed on a Samsung Galaxy S5 smartphone and calibrated for sound measurement. Data were collected during outbound, non-patient legs of 45 retrievals - 25 road, 11 fixed wing aircraft and 9 rotary aircraft journeys. Data were saved to cloud storage, then analysed using PostgreSQL database.

RESULTS

The median sound level was 83 dB (interquartile range 66-91; range 27-≥97 dB). Continuous equivalent sound (L_eq ) was 90 dB across all journeys. Rotary transport was loudest (L_eq 94 dB). Fixed wing (L_eq 89 dB) and road (L_eq 87 dB) journeys also resulted in significant sound exposure. Sound exceeded recommended levels (45 dB) for 99% of all journey time, regardless of the mode of transport.

CONCLUSIONS

Neonates encounter harmful sound levels during retrieval - louder than recommended levels for 99% of all retrieval time. Sounds levels were highest in rotary aircraft transport compared to fixed wing or road transport. It is feasible to use a calibrated smartphone application instead of a sound metre.

Whole-body vibration in neonatal transport: a review of current knowledge and future research challenges

Interfacility transport to tertiary care for high-risk neonates has become an integral part of equitable access to optimal perinatal healthcare. Excellence in clinical care requires expertise in transport medicine and the coordination of safe transport processes. However, concerns remain regarding environmental stressors involved in the transportation of sick high-risk neonates, including noise and vibration. In order to mitigate the potential deleterious effects of these physical stressors during transport, further knowledge of the burden of exposure, injury mechanisms and engineering interventions/modifications as adjuncts during transport would be beneficial. We reviewed the current literature with a focus on the contribution of new and emerging technologies in the transport environment with particular reference to whole-body vibration. This review intends to highlight what is known about vibration as a physical stressor in neonates and areas for further research; with the goal to making recommendations for minimizing these stressors during transport.

Cabin Layout Optimization for Vibration Hazard Reduction in Helicopter Emergency Medical Service

Helicopter Emergency and Medical Service (HEMS) vehicles require a specially configured cabin that supports the quick transport of a rescue team to the site of an emergency and return of patients back to a full capacity hospital, while sustaining the patients’ health using specifically designed, but otherwise state-of-the-art life-support equipment. The effectiveness and safety of the service may be challenged by the vibratory level, which could be improved by optimally positioning the affected subjects within the cabin. However, the bare dynamical response of the airframe can lead to erroneous evaluation of vibration performance, since pilots, crew, patients, and medical equipment dynamically interact with the helicopter through their interfaces with the structure. Therefore, layout optimization of a HEMS vehicle for low vibration requires the capability to efficiently analyze a large set of candidate coupled helicopter-interface-subject configurations, reaching a suitable trade-off between model detail and computational cost. This work presents an effective vibration rating of medical helicopters to support vibration hazard reduction by minimization of cabin interior accelerations. The tool is able to model high-fidelity rotorcraft aeroservoelasticity, easily connect formulations representing the dynamics of humans, equipment, and their interfaces, and calculate the vibration performance of the resulting coupled models. The approach is applied to a medium-weight helicopter to find its lowest vibration HEMS configuration. It is demonstrated that the optimal positioning of HEMS subjects can significantly reduce vibration hazard and improve operation safety, nearly as effectively as the application of vibration attenuation solutions with a fixed cabin layout.

Rethinking the neonatal transport ground ambulance

Objectives

This article describes the detailed project aimed to realize a dedicated ground ambulance for neonatal emergency transport service (NETS). To date, the European Community rules specify requirements for the design, testing, performance, and equipping of road ambulance used for transport and care of adult injured or ill patients, completely ignoring neonatal transport.

Methods

The project consisted of electric and gas supply planning, interior design taking into account ergonomic and occupant protection principles, both during travel and during medical care performances.

Results

A detailed project is presented. Main differences between European Type C ambulance and the new proposed Type D neonatal ground ambulance are the presence on board of air compressed cylinder, iNO cylinders and delivery system, phototheraphy, shock adsorbing stretcher support, cooling device, patient’s placenta (refrigeration box), and transcutaneous gas analyzer.

Conclusion

The European Community rules specify requirements for road ambulance used for transport and care of adult injured or ill patients, completely ignoring neonatal transport.

This study describes the detailed project aimed to realize a dedicated ground ambulance for neonatal emergency transport service. This study demonstrated that it is not possible simply to adapt the currently dedicated ambulance for mobile intensive care and resuscitation services (actual type C European Community) in a modern dedicated NETS ambulance; it is of paramount importance suggesting to European Community to introduce a further ambulance type, to be identified type D, strictly reserved to neonatal transport activities.

Nationwide survey of neonatal transportation practices in Italy

BACKGROUND

Despite regionalization of perinatal care provides for the "in utero" transfer of high-risk pregnancies, there will always be a number of neonates who undergo acute inter-facility transport. The presence of a well-organized Neonatal Emergency Transport Service (NETS) can prevent and reduce risks of transportation, especially for very preterm infants, and is therefore mandatory for any program of regionalization of perinatal care. Italian National Health System is highly decentralized and Regions are autonomous to structure, plan and delivery their regional health services. Consequently, organization models and resources available vary widely and significant regional differences in access and quality of health services have been reported in the past years. A national survey was conducted in 2015 by the neonatal transport study group of the Italian Society of Neonatology with the aim to describe neonatal transfer practices and to assess the Neonatal Emergency Transport Services (NETS) status in the 20 Italian regions.

METHODS

A questionnaire regarding neonatal transfer practices and NETS activity for the previous year (2014) was sent to the 44 NETS operating in the 20 Italian regions. Demographic data were obtained from the Italian National Statistical Institute (ISTAT).

RESULTS

The overall survey response rate was 100%. In 2014, only 12 (60%) of the 20 Italian regions were fully covered by NETS, 3 (15%) regions were partially covered, while neonatal transport was not available in 5 (25%) regions. Overall, in 2014, the 44 NETS operating in Italy transported a total of 6387 infants, including 522 (8.17%) having a gestational age < 28 weeks.

CONCLUSIONS

The organization of NETS in Italy is devolved on a regional basis, resulting in a large heterogeneity of access and quality to services across the country. Where available, NETS are generally well-equipped and organized but limited volume of activities often cannot guarantee adequate levels of skills of personnel or an appropriate cost-efficiency ratio. The regions reported with lack of NETS have managed, or are trying, to fill the gap, but continuing efforts to reduce regional differences in the availability and quality of services are still needed.

[Noise level in the NICU: Impact of monitoring equipment]

BACKGROUND

The sound level in the neonatal intensive care unit (NICU) may induce adverse effects for neonates, their family, and the staff. This study evaluated the sound level in a NICU before and after the implementation of an educational program.

MATERIAL AND METHODS

A baseline audit determined the most exposed area of the NICU and the most exposed periods over 24 h. Then an educational program started, including sound level measurement methods, side effects for neonates, results from the baseline audit, and new visual monitoring equipment (SoundEar^®). Sound levels were measured before, 1, 2, and 3 months after starting the educational program and the use of SoundEar^®. The NICU staff was blind to the periods of sound level measurements.

RESULTS

The base noise level was high, especially near the central part of the NICU and during transmission time (mean Leq: 60.6±3.6dB(A); sound peaks: 94.8±6.8dB(A)). A decrease in the sound level (P<0.001) was found 1 and 2, but not 3 months after starting the educational program. It remained high compared to the guidelines.

CONCLUSION

Human activity was responsible for most of the sound level. An educational program was effective in reducing the sound level, but did not reach the guideline's target. The continuous use of sound-monitoring equipment after starting the project reduced the sound level for 2 months, but no longer. Therefore, a continuous educational program about the sound level in the NICU including feedback monitoring every 2-3 months should be encouraged.

Implementing a Neonatal Transport System With Simulation in Kosovo

OBJECTIVE

Post-war Kosovar health care systems have reduced gaps in maternal and newborn health care. Coordinated neonatal transport programs may further improve survival and morbidities.

METHODS

Transport care paradigms were tested using in situ (Kosovo) and ex situ (the United States) mobile immersive simulation. Patient demographics and outcomes were measured at the tertiary referral center.

RESULTS

Four paired physician and nurse transport teams performed 7 simulated interfacility transports across Kosovo. In situ simulations revealed safety threats in facilities, ambulances, and team process. Ex situ observations reinforced roles and professionalism. For the first year after simulations, tertiary neonatal intensive care unit admissions were more premature (-2.4 weeks), smaller (-725 g), and out born (+12%). Mortality was higher (14.7% vs. 7.8%), hypothermia was lower (0.2% vs. 4.6%), and culture-positive sepsis was lower (15.7% vs. 42.9%).

CONCLUSION

In situ augmented by ex situ simulation provided perspective and depth of understanding to implement a new care delivery paradigm. Simulations involving Kosovar health care providers across a network of facilities generated practical experience in nationwide neonatal transport, with temporal association to altered referral patterns at the tertiary care facility.

Decreasing sound and vibration during ground transport of infants with very low birth weight

OBJECTIVE

To measure the effectiveness of modifications to reduce sound and vibration during interhospital ground transport of a simulated infant with very low birth weight (VLBW) and a gestational age of 30 weeks, a period of high susceptibility to germinal matrix and intraventricular hemorrhage.

STUDY DESIGN

Researchers measured vibration and sound levels during infant transport, and compared levels after modifications to the transport incubator mattresses, addition of vibration isolators under incubator wheels, addition of mass to the incubator mattress and addition of incubator acoustic cover.

RESULT

Modifications did not decrease sound levels inside the transport incubator during transport. The combination of a gel mattress over an air chambered mattress was effective in decreasing vibration levels for the 1368 g simulated infant.

CONCLUSION

Transport mattress effectiveness in decreasing vibration is influenced by infant weight. Modifications that decrease vibration for infants weighing 2000 g are not effective for infants with VLBW. Sound levels are not affected by incubator covers, suggesting that sound is transmitted into the incubator as a low-frequency vibration through the incubator's contact with the ambulance. Medical transportation can apply industrial methods of vibration and sound control to protect infants with VLBW from excessive physical strain of transport during vulnerable periods of development.

[Utility of a physiologic stability index based on Transport Risk Index of Physiologic Stability (TRIPS) for the evaluation of infants transferred to a specialized hospital]

BACKGROUND

Neonatal mortality is a public health priority. We review the physiological instability of the newborn after a transfer, which contributes to increased neonatal mortality. The objective of this work was to determine whether the Transport Risk Index of Physiologic Stability (TRIPS) in newborns transferred to the Neonatal Intensive Care Unit of a secondary hospital serves as a predictor of early neonatal mortality.

METHODS

We use the TRIPS to predict neonatal death in the first 7 days after patients' admission.

RESULTS

Neonatal mortality at 7 days after admission is related to the TRIPS rating. The score of the survivors and neonatal deaths show a significant difference (p: 0.009). For a score of 16, a sensitivity of 62% and a specificity of 84%; area under the curve of 0.757 was determined.

CONCLUSIONS

Physiological index weighting using TRIPS is a good predictor of neonatal mortality. It is important to establish measures to improve physiological stability of the newborn before, during and after the transfer in order to reduce neonatal mortality.

Heart rate variability of transported critically ill neonates

Determining heart rate variability (HRV) in infants is a useful measure of physiological stability. Transport of ill neonates imposes a measurable degree of stress. A prospective observational study on 58 critically ill neonates, transported to an intensive care unit (ICU) was performed. HRV during the 24-h period before, during and after transport, heart rate (HR), mean arterial pressure and transport risk index of physiologic stability (TRIPS) score were observed. The median HRV total power value of 40.80 ms(2) was set as the cutoff value, and neonates with values below this were designated as the low-HRV group (l-HRV; n=29), and those above this as the high-HRV group (h-HRV; n=29). The h-HRV group had a significantly lower HR at retrieval and 1 h after admission and a significant 2- and 4-day shorter duration of mechanical ventilation and ICU treatment compared to the l-HRV group. Spearman's correlations between total power and duration of mechanical ventilation (ρ=-0.346; P<0.01) and ICU treatment (ρ=-0.346; P<0.01) were significant. Transported neonates were also tested for differences in HRV and other physiological and demographic parameters between the transport mode and time. No differences were found, except that the nighttime ambulance group had a statistically higher HRV compared to the daytime ambulance group.

CONCLUSION

Higher HRV of group of neonates, who did not differ in illness severity TRIPS score from the lower HRV group, is associated with a faster and significant decrease in HR after transport and a 2- and 4-day shorter duration of mechanical ventilation and ICU treatment.