audit heated and humidified nasal cpap on neonatal transport · fisher paykel humidifier. if the...

82 V O L U M E 8 I S S U E 3 2 0 1 2 infant

A U D I T © 2012 SNL All rights reserved

The importance of heating andhumidifying airway gases administered

via a mechanical ventilator has been wellestablished. If inspired gases are notadequately humidified, the respiratorysystem can be compromised throughthickened secretions and damage to ciliaand mucus membranes1.

In the transport setting every effort ismade to maintain the standards ofintensive care that the baby receives in thenursery. Practices are constantly assessedand reviewed to identify problematic areas.An internal audit in 2010 showed thattransferring neonates on continuouspositive airway pressure (CPAP) led to adecrease in axilla temperature for somepatients2. At the time Embrace had nomeans to actively humidify ventilator gason transport. The audit showed a trendtowards a longer stabilisation time as teamsattempted to optimise the temperaturebefore departure by increasing the

Heated and humidified nasal CPAP onneonatal transportIt is widely accepted that neonatal patients who require airway support should receive heatedand humidified gases. This can be a challenge when providing short-prong nasal continuouspositive airway pressure (CPAP) in the transport environment. This article describes how heatedand humidified gases can be provided during transport in this group of patients and describesthe results of an audit into its effectiveness.

Ian BraithwaiteRN(CH), BEngSenior Transport Nurse, [email protected]

Karen SpinksRGN, RSCN, MSc Advanced Clinical PracticeAdvanced Neonatal Nurse Practitioner,Embrace

Claire DavidsonMBChB, MRCPCHTransport Registrar, Embrace

Cath HarrisonBMedSci, BM, BS, DTM&H, FRCPCHLead Neonatologist for Embrace

Yorkshire and Humber Infant and ChildrenTransport Service, Capitol Business Park,Barnsley

Keywords

continuous positive airway pressure;humidification; neonatal transport;ventilation

Key points

Braithwaite I., Spinks K., Davidson C.,Harrison C. Heated and humidified nasalCPAP on neonatal transport. Infant 2012;8(3): 82-85.1. Humidification of ventilated gases is

possible to achieve safely andeffectively on transport.

2. Patient temperature data demonstratesthe benefit of using activehumidification with transport CPAP.

transport incubator temperature or using achemical gel mattress. Despite these efforts43% of babies included in the audit arrivedat their destination with an axillatemperature of <36.6°C (FIGURE 1). Afterthe 2010 audit, the investigators sought toobtain the necessary equipment to activelyhumidify ventilator gas during transportand to assess this change in practice.

Current practiceThere is a wide variety in practicethroughout the UK in terms of humidityand how it can be provided in thetransport setting. In a survey carried out bythe Peninsula Transport service in 2011,Madar found that 18 out of 21 UKneonatal transport teams were able toprovide either actively or passivelyhumidified ventilator gases. Of the tenservices utilising the Babypac (SmithsMedical, UK) ventilator, two did nothumidify gases, five used only heat

FIGURE 1 Mean axilla temperatures for patients on non-humidified CPAP, 2010 audit.

80%

70%

60%

50%

40%

30%

20%

10%

0%

Perc

enta

ge o

f tra

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Referral baby temperature Arrival baby temperature

<36.6 36.6-37.2 >37.2 degrees Celsius

Heated and humidified nasal CPAP on neonatal transport_layout 25/04/2012 15:00 Page 82

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V O L U M E 8 I S S U E 3 2 0 1 2 83infant

moisture exchangers (HME) and three alsohad access to active humidity3.

Embrace use Babypac ventilators toprovide ventilation for neonatal patients.The babies are nursed in Ti-500 incubators(Draeger Medical). Additional warmth, ifrequired, is provided by single-use‘Transwarmer’ chemical gel mattresses(CooperSurgical, USA).

For intubated patients a non-humidifiedcircuit (Intersurgical, UK) is used, togetherwith a Humid-Vent Mini (Gibeck/Teleflex,Ireland) HME. An HME is a passivehumidification device which traps expiredheat and moisture in a membrane. The gaspasses back over the membrane oninspiration allowing some of the heat andmoisture to be recaptured. HMEs inneonates are not as effective as activehumidification, but are consideredacceptable for short-term use4. A recentCochrane Review showed that bodytemperature was significantly decreasedwhen an HME was used compared withheated humidifiers5.

Short-prong nasal CPAP is providedusing the BabyFlow system (DraegerMedical, UK). These are short nasal prongswhich attach to the ventilator using simpleunheated tubing. The Humid-Vent MiniHME is designed to attach to anendotracheal tube and so cannot be usedin this circuit.

EquipmentThere are a variety of options available totransport services to actively heat andhumidify ventilator gases. Some ventilatorshave an integrated humidification system,eg the Reanimator F-120 (Stephan,Germany). Using new ventilators for thestudy was not feasible so two potentialstand-alone humidifiers were reviewed(TABLE 1).

The Neo-pod T (Westmed, UK) is ahumidifier specifically designed for thetransport environment. The waterchamber sits inside the incubator, with anexternal control panel and power supply.The equipment is light-weight and simpleto operate. The ventilator circuits were feltto be too short for use in the study andalthough the manufacturer can providelonger circuits, they were not availablewithin the audit time frame.

The MR850 (Fisher Paykel, UK) is ahumidifier commonly used in nurseries inthe region and Embrace staff are familiarand experienced with the product. It ishowever bulky, relatively heavy and

expiratory port of the ventilator was noted.The volume of water was dependent onambient conditions and incubatortemperature. The experience of othertransport services gave reassurance thatthis water does not infiltrate the ventilatorduring routine use.

For added fixation security, Paraid(Birmingham, UK) developed a securebracket (FIGURE 2) to attach onto thetransport trolley that meets Europeanincubator transport standards7.

Completion of the 2011 auditTransport teams were asked to fill in anaudit form for patients transferred in anincubator on short-prong nasal CPAP.Planned, unplanned and time-criticaltransfers were included. Transfers from anoperating theatre or X-ray departmentwere excluded as the procedure orinvestigation may have impacted thepatient’s temperature. The data collectionran for a six-and-a-half month periodfrom June 17th to December 31st 2011.

One out of the four Embrace transportincubator trolleys was set up with theFisher Paykel humidifier. If the humidifier

requires a mains power supply. Theinvestigators chose to use this humidifier asthey were readily available within the basehospital, and the circuit lengths wereappropriate. The dedicated Embraceambulances have 240v AC inverters sopower could be supplied to the humidifiersduring the journey.

The Babypac ventilator is not commonlyused with humidified circuits. Work wasundertaken with both Fisher Paykel andSmiths Medical to establish that thecombination would be safe and effective.The humidifier was positioned below boththe ventilator and the patient. Thechamber auto-fill line was not used toremove the risk associated with hanging abag of water. The ventilator was used inconstant-flow mode. A calibratedreference-grade pressure monitor was usedto quantify the pressure drop across thecircuit due to the added flow resistance andthis was taken into account clinically.

Variations in humidifier performancerelated to external factors such asenvironmental temperature have beendescribed6. Despite the use of dual-limbheated circuits, condensation at the

TABLE 1 Comparison of equipment for humidity.

Humid-Vent MiniHME

Fisher Paykel MR850Humidifier

Westmed Neo-pod THumidifier

Weight (excludingcircuit)

4 grams 2,800 grams 200 grams

Power Supply N/A AC DC or AC

Temperature andhumidity(manufacturer’sdata)

Humidity 30mgH2O/L at a tidalvolume of 20mL

Humidity >33mgH2O/L

Chamber 35.5-42°C

Airway 35-40°C

No humidity data inproduct information.

Chamber 30-38°C

Additional circuitdead-space

2.4mL N/A N/A

FIGURE 2 MR850 humidifier in bracket.


trolley was available at the time of referralit was used for the CPAP patient, otherwiseanother trolley was used and non-humidified CPAP was provided.

Embrace use axilla and abdominal skintemperature measurements as coretemperature surrogates for patients whorequire a level of care consistent withreceiving CPAP. The skin temperature ismonitored continuously during thejourney via the incubator skin probe whichis fixed to the skin over the patient’s liverwith a heat-reflective sticker. An internalaudit found a good correlation betweenskin temperature and axilla temperature8.Embrace aspire towards precisetemperature control on transport andconsider 36.6 to 37.2°C to be an acceptablerange of axilla temperatures. Theseparameters are tighter than somepublished guidelines9, but provide a factorof safety and allow for measurement error.

Data were collected on incubatortemperature, Transwarmer use,stabilisation time and the total time thepatient spent on transport CPAP. Transportteams were asked to indicate if there wereany adverse events, including delays relatedto thermoregulation or equipment.

ResultsThere were 94 CPAP transports that metthe audit inclusion criteria and 64 auditforms were completed (68%). Twopatients were excluded; one had missingdata and one deteriorated en-route andthe team returned to the referral hospital.The remaining 62 transports wereanalysed and split into humidified andnon-humidified groups.

There were similar demographics inboth groups, although the non-humiditygroup had a slightly lower gestational ageat time of transfer (TABLE 2).

FIGURE 3 compares incubatortemperatures on the arrival of thetransport team at the patient’s cot-side inthe referring hospital, the transport

incubator set-temperature on departurefrom the referring unit and the incubatorset-temperature on arrival at thedestination unit. Ten of the total numberof patients (16%) were nursed underradiant warmers at the referring hospitaland did not count towards the initial meanvalues. Initial incubator and patienttemperatures at the referring hospitalswere similar for both groups, as werestabilisation time and total time ontransport CPAP (TABLE 2).

Most temperature-related interventions,issues and delays occurred in the non-humidified group (TABLE 3). Whenanalysed in detail the interventions werealmost entirely related to patients <1300grams or <31 weeks’ corrected gestation.There was no clear correlation with age orgestation at birth.

FIGURES 4 and 5 show axilla temperaturesmeasured at either end of the transportepisode: the arrival of the transport team atthe patient’s cot-side in the referringhospital, and at handover of the patient atthe destination hospital. FIGURE 4 illustratesan improvement in temperature controlsince the original audit (FIGURE 1), evenwithout humidified CPAP. However the

addition of humidification almosteradicated hypothermia in patientstransported on CPAP; only 11% had skintemperatures that fell below 36.6°C at anypoint during the journey (TABLE 3), and nopatient arrived at the destination with anaxilla temperature below 36.6°C (FIGURE 5).

FIGURE 3 shows that without humidity,transport incubator temperatures onarrival were on average around 3°C higherthan unit incubator temperatures (33°C).With humidity they were around 1°Chigher. The incubator temperature forpatients who received humidity wassignificantly reduced during the journey inresponse to the patient’s skin temperature(Student’s T-Test p=0.03).

DiscussionSince the disappointing results of theoriginal audit there has been a greateremphasis on achieving appropriatetemperature control within the service andtransport teams usually set a highertransport incubator temperature forpatients receiving CPAP in expectation oftemperature-related challenges. HoweverFIGURE 5 shows that 23% of patients in thehumidified group arrived with an axillatemperature of greater than 37.2°C and thedownwards trend of transport incubatortemperatures in this group suggests thatthey were initially set too high for thepatient. With the introduction ofhumidified CPAP and in the light of theaudit results, initial transport incubatortemperature settings need to bereconsidered. The investigatorsacknowledge that there is a group ofmature infants for whom temperaturecontrol is difficult because they are only

A U D I T

84 V O L U M E 8 I S S U E 3 2 0 1 2 infant

Non-humidity (n=36) Humidity (n=26)

Gestation, mean completed weeks 28 (24-40) 28 (24-40)

Corrected gestation, mean completed weeks 31 (26-40) 32 (27-44)

Age, mean days 17 (1-52) 28 (1-58)

Weight at transport, mean grams 1360 (730-3550) 1350 (630-3600)

Stabilisation time, mean minutes 79 (34-215) 73 (30-175)

Time on transport CPAP, mean minutes 103 (43-185) 117 (55-215)

TABLE 2 Demographics and times for stabilisation and transport, range in brackets.

FIGURE 3 Mean incubator temperatures for patients transported on CPAP, mean values +/-standard error of the mean.

37

36

35

34

33

32

Deg

rees

CReferring inc temp Departure transport inc temp Arrival transport inc temp



being nursed in an incubator due to theneeds of the transfer process10.

There were several limitations associatedwith this project. The small sample sizeand lack of randomisation may havereduced the quality of the results, althoughprobably not the general conclusions. Therecording of temperature-relatedinterventions has now been made manda-tory in the Embrace transport paperwork,and compliance will be audited.

Safety was of primary importancethroughout the project. There were noadverse incidents related to the equipment.The weight of the humidifier was offset bythe removal of two syringe pumps fromthe incubator trolley. Staff found thehumidification set-up easy to use, and theintroduction of extra equipment did notimpact on stabilisation times.

Adding new equipment to a transportservice has a potential financial impact interms of consumable use. Humidifiercompatible ventilator circuits are moreexpensive than comparable non-heatedversions, but this additional cost was offsetby a dramatic reduction in Transwarmermattress usage. Without considering theinitial capital equipment costs, the practicechange was cost-neutral.

ConclusionsBabies on humidified CPAP had bettertemperature control during transport withno temperature-related stabilisation delays.

Fewer Transwarmer mattresses wereneeded in this group yet there were noinstances of babies arriving at the referralunit with sub-optimal temperatures. Therewere subjective reports of increased patientcomfort and improved tolerance of CPAP.The patient temperature data, togetherwith the unseen protection given todelicate airways, demonstrates the benefitof using humidification during CPAP withneonates during transport.

The results of this study showed that agreater number of babies in the humidifiedgroup became too warm (axillatemperature >37.2°C) compared with thenon-humidified group. Episodes ofhyperthermia may be detrimental to theneonate and should be avoided11. It isanticipated that improved experience andconfidence may reduce the incidence ofenvironmental hyperthermia.

Extending the quality of care provided inthe intensive care nursery to the transportsetting would suggest that humidifiersshould also be used for ventilated patientsas well as all infants who receive CPAP. Theuse of active humidification for intubatedpatients will be developed and there will beaudit of this practice to compare it withpassive humidification using an HME.

Acknowledgements

The authors would like to acknowledgeDr John Madar and Mark Mulcahy fromthe Peninsula Neonatal Transport Service.

Declarations of interest

None

References1. Burton J.D. Effects of dry anaesthetic gases on resp-

iratory mucous membrane. Lancet 1962;1:235-38.

2. Babarao S. Neonatal CPAP transfers in Yorkshire &

Humber (unpublished internal audit). Embrace.

2010.

3. Madar J. Ventilator humidity on transport

(unpublished survey, personal communication).

2011.

4. Fassassi M., Michel F., Thomachot L. et al. Airway

humidification with a heat and moisture exchanger

in mechanically ventilated neonates: a preliminary

evaluation. Intensive Care Med 2007;33:336-43.

5. Kelly M., Gillies D., Todd D.A., Lockwood C. Heated

humidification versus heat and moisture

exchangers for ventilated adults and children.

Cochrane Collaboration. 2010;1:1-90.

6. Todd D.A., Boyd J., Lloyd J., John E. Inspired gas

humidity during mechanical ventilation: effects of

humidification chamber, airway temperature probe

position and environmental conditions. J Paediatr

Child Health. 200;37:489-94.

7. CEN Standards. Rescue systems-Transportation of

incubators-Part 2: System requirements (draft). EN

13976-2:2011.

8. Spinks K. A comparison of skin temperature probes

and axilla temperature (unpublished internal audit).

Embrace. 2009.

9. Waldron S., Mackinnon R. Neonatal thermo-

regulation. Infant 2007;3:101-04.

10. Bowman E. Control of temperature during newborn

transport: An old problem with new difficulties.

J Paediatr Child Health. 1997;33:398-401.

11. Department of Reproductive Health and Research

(RHR), World Health Organisation. Thermal

protection of the newborn: a practical guide

(WHO/RHT/MSM/97.2). Geneva: World Health

Organisation. 1997.

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Transwarmer use 36% 8%

Skin temperature dropping below 36.6°C at any point during the journey, even transiently 42% 11%

Temperature control-related delays to transport 14% 0%

TABLE 3 A comparison of three markers of temperature control improvement.

FIGURE 4 Mean axilla temperatures for patients on non-humidifiedCPAP, 2011 audit.

80%

70%

60%

50%

40%

30%

20%

10%

0%

Perc

enta

ge o

f tra

nsp

orts

Referral baby temperature Arrival baby temperature

<36.6 36.6-37.2 >37.2 degrees Celsius

FIGURE 5 Mean axilla temperatures for patients on humidified CPAP,2011 audit.

80%

70%

60%

50%

40%

30%

20%

10%

0%

Perc

enta

ge o

f tra

nsp

orts

Humidity referral baby temperature Humidity arrival baby temperature

<36.6 36.6-37.2 >37.2 degrees Celsius


audit heated and humidified nasal cpap on neonatal transport · fisher paykel humidifier. if the...

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