Continuous positive airway pressure and noninvasive ventilation in prehospital treatment of

13 Pages·2014·0.42 MB·English

Bakkeetal.ScandinavianJournalofTrauma,ResuscitationandEmergencyMedicine2014,22:69
http://www.sjtrem.com/content/22/1/69
REVIEW Open Access
Continuous positive airway pressure and
noninvasive ventilation in prehospital treatment
of patients with acute respiratory failure: a
systematic review of controlled studies
Skule A Bakke1*, Morten T Botker2, Ingunn S Riddervold2, Hans Kirkegaard3 and Erika F Christensen2
Abstract
Continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV) are frequently used inhospital for
treating respiratory failure, especially intreatmentof acute cardiogenic pulmonaryedema and exacerbation of
chronic obstructive pulmonarydisease.Early initiation oftreatmentis important for success and introduction
already in the prehospital setting maybe beneficial. Our goal was to assess theevidence for an effect of
prehospital CPAP or NIV as a supplementto standard medical treatmentalone on thefollowing outcome measures;
mortality, hospital length ofstay, intensive care unit length ofstay, and intubationrate. We undertooka systematic
review based on a search in thethreedatabases: PubMed, EMBASE, and Cochrane. We included 12 studies inour
review, but only four of thesewere ofacceptable size and quality to concludeon our endpoints ofinterest.Allfour
studies examine prehospitalCPAP. Ofthese, only one small, randomized controlled trial shows a reduced mortality
rate and a reduced intubation rate with supplemental CPAP. The other three studies have neutralfindings,but in
two ofthese a trend toward lower intubation rate is found. The effect of supplemental NIV has only been evaluated
insmaller studies withinsufficient power to conclude onour endpoints. None of thesestudies have shown an
effect on neither mortality nor intubation rate,but two small, randomized controlled trials show a reduction in
intensive care unit length ofstay and a trend toward lower intubationrate. The risk ofboth typetwo errors and
publication bias is evident, and thefindings are not consistent enough to make solid conclusion on supplemental
prehospital NIV.Large, randomized controlled trials regarding theeffectof NIV and CPAP as supplement to
standard medical treatmentalone, inthe prehospital setting, are needed.
Keywords: Prehospital, Continuous positive airway pressure, Noninvasive ventilation, Respiratoryfailure, Acute
pulmonary edema, Chronic obstructive pulmonarydisease,Mortality, Hospitallengthof stay, Intensivecare unit
length ofstay, Intubation rate
Introduction defined as one of the top priority research questions in
Dyspnea is a frequent symptom among patients in the physician-providedprehospitalcriticalcare[2].
prehospital setting [1]. Common causes of nontraumatic Continuous positive airway pressure (CPAP) and non-
dyspnea are congestive heart failure,pneumonia,chronic invasive ventilation (NIV) are often used in intensive
obstructive pulmonary disease, and asthma [1]. The ap- care units for treating respiratory failure caused by acute
plication of advanced airway management and alterna- cardiogenic pulmonary edema (ACPE) and acute exacer-
tive devices in the prehospital setting has recently been bation of chronic obstructive pulmonary disease
(COPD). CPAP-systems apply positive airway pressure
with only minimal differences in the pressure applied
during inspiration and expiration [3]. The term NIV
*Correspondence:[email protected]
1DepartmentofAnesthesiology,HospitalofSouthernJutland,Southern covers different forms of noninvasive positive pressure
Jutland,Denmark ventilation, which in contrast to CPAP can also ad extra
Fulllistofauthorinformationisavailableattheendofthearticle
©2014Bakkeetal.;licenseeBioMedCentralLtd.ThisisanOpenAccessarticledistributedunderthetermsoftheCreative
CommonsAttributionLicense(http://creativecommons.org/licenses/by/4.0),whichpermitsunrestricteduse,distribution,and
reproductioninanymedium,providedtheoriginalworkisproperlycredited.TheCreativeCommonsPublicDomain
Dedicationwaiver(http://creativecommons.org/publicdomain/zero/1.0/)appliestothedatamadeavailableinthisarticle,
unlessotherwisestated.
Bakkeetal.ScandinavianJournalofTrauma,ResuscitationandEmergencyMedicine2014,22:69 Page2of13
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inspiratory support driven by a ventilator, thereby giving [Mesh] OR prehospital OR pre-hospital OR out of
positive pressure ventilation[3,4]. Standardmedical treat- hospital).
mentgivenforacuterespiratoryfailureisdiverse,depend- We systematically excluded studies that did not meet
ing on assumed cause and type of emergency medical the inclusion criteria in a hierarchical manner according
staffing. It ranges from simple supplemental oxygen ther- tothefollowingexclusioncriteria:
apytonitrates,diuretics,opioids,inhaledbronchodilators,
and inotropic infusions. The worst cases can result in 1. StudiesnotregardingCPAP orNIV
endotrachealintubation. 2. Notprehospitalsetting
Recent Cochrane reviews show lower mortality and 3. Notacute respiratoryfailure ofanycause
reduced intubation rate with the use of inhospital supple- 4. Notaclinicaltrial
mental CPAP and NIV, compared to standard medical 5. Notacontrolled design comparing supplemental
treatmentalone,inpatientswithACPE andexacerbations CPAP orNIVto standard medical treatmentalone
ofCOPD[5,6].Lowerintubationratesdecreasetheriskof 6. Notadultpatients(≥18years)
complicationsrelatedtoendotrachealintubationandinva- 7. Abstractonly
siveventilation,especiallypulmonaryinfections[7-9].
Prehospital intubation is associated with high success- First the title of a study, as it appeared from the search
rates in physician-staffed services [10]. However, aspir- pages in the respective databases, was read and searched
ation of gastric contents during intubation is reported for the exclusion criteria described above. If a study could
more frequent in the prehospital setting than in the not be excluded based on its title, the abstract was read.
emergency department [11]. One study reports compli- Based on the abstract, we excluded studies that did not
cations in 14% of prehospital advanced airway manage- meettheinclusioncriteriainthesamehierarchicalmanner.
ments [12]. Especially vomiting, hypotension, and If exclusion could not be done based on the abstract, the
hypoxiadooccur,butonlyaminorproportion ofthepa- entire article was read. By this selection process, studies
tients in this study would have been suitable for CPAP/ withinhomeuseofnoninvasiveventilationforchronicpul-
NIV as only 21% were intubated because of hypoxia. monarydisorders,CPAPorNIVduringintrahospitaltrans-
More than half of the patients had cardiac arrest. A pre- port, expert opinions, editorials, reports, and case series
requisiteforsuccessfulnoninvasivetreatmentisearlyiniti- were excluded. Duplications and conference abstractswere
ation of CPAP or NIV [13,14]. Thus it is reasonable to removed. Two reviewers independently carried out the
believethatmanypatientswouldbenefitfromearlieriniti- searches,anddiscrepanciesregardingexclusionweresolved
ation of noninvasive treatment, in the prehospital setting, by consensus. Subsequently, a hand-search through refer-
toavoidintubationandimprovepatientoutcome. ences in the included studies, relevant reviews, and the
The objective of this systematic review of controlled “relatedcitations”featureonPubMedwasperformed.Two
studieswastoexamine,whetherCPAPorNIVinitiatedin reviewers independently extracted study details from the
theprehospitalsettingreducemortality,abbreviatehospital included articles, searching for our endpoints of interest:
length of stay (H-LOS), abbreviate intensive care unit mortality, H-LOS, ICU-LOS, and intubation rate. Discrep-
length of stay (ICU-LOS), or lower intubation rate when ancies regarding data extraction were solved by consensus.
usedasasupplementtostandardmedicaltreatmentalone. The included studies were independently evaluated by two
reviewers according to the Scottish Intercollegiate Guide-
Review linesNetwork50(SIGN50)checklistforrandomizedand/
Methods or controlled trials [15]. SIGN implements the Grading of
Published studies relevant for this review were identi- Recommendations Assessment, Development, and Evalu-
fied by a search in the databases PubMed, EMBASE, ation(GRADE)WorkingGroupsapproachwithinitsmeth-
and Cochrane on April 4th 2013 and updated January odology.TheSIGN50checklistssectiononeshowsquality
19th 2014. Our inclusion criteria were: Controlled stud- of evidence rated in one of four categories (ranging from
ies examining the effect of supplemental prehospital “well covered” to “not addressed”). Section two starts by
CPAP or NIV, compared to standard medical treatment rating the methodological quality of the study, based on
alone, in adult patients with acute respiratory failure of answersinsectiononeandusingthefollowingcodingsys-
any cause. In PubMed the following search string was tem: High quality (++): The majority of criteria are met.
used: (“Continuous Positive Airway Pressure” [Mesh] Thereislittleriskof bias. Resultsareunlikelytobe chan-
OR “Noninvasive Ventilation” [Mesh] OR non invasive ged by further research. Acceptable quality (+): Most of
ventilation) AND (“Respiratory Insufficiency” [Mesh] the criteria are met. There could be some flaws in the
OR “Pulmonary disease, Chronic obstructive” [Mesh] OR study with an associated risk of bias. Conclusions may be
“Heart Failure”[Mesh] OR “Pulmonary Edema” [Mesh] OR changed by further research. Low quality (−): Either most
“Asthma” [Mesh]) AND (“Emergency medical services” criteria are not met, or there are significant flaws relating
Bakkeetal.ScandinavianJournalofTrauma,ResuscitationandEmergencyMedicine2014,22:69 Page3of13
http://www.sjtrem.com/content/22/1/69
to key aspects of study design. We were aware that alone. It was therefore excluded [18]. Finally, one study
included studies would be heterogeneous, but used the was excluded because it is a cost-benefit analysis and
same checklist to assess all types of controlled studies not a clinical trial [19]. One study does not report if
in order to improve the systematic approach and crit- standard medical treatment was used in the interven-
ical evaluation. tion group and an email was sent to the corresponding
To minimize bias, two reviewers evaluated each author for clarification, but there was no reply. Based
study independently. Differences in assessment were on our evaluation of the methods section, both inter-
discussed and discrepancies solved by consensus with vention and control groups received medical treatment
a third reviewer. We have presented the results from andthestudywasthusincludedforanalysis[20].Another
all studies, but our conclusion is based only on studies study does not state a primary endpoint, but reports on
rated+or ++. endpoints of interest for our review and was thereforein-
cluded[21].Thusweincluded12studiesforfinalanalysis
Results [16,20-30]. Of the included studies, eight studies examine
We located 196 published studies searching PubMed, CPAPas intervention[16,22-25,27,28,30] and fourstudies
290studiessearchingEMBASE,and228studiessearch- examineNIVasintervention[20,21,26,29].
ing Cochrane, yielding a total of 714 studies. Of these, Overview of study design and main findings of the
700 studies were excluded based on titles or abstracts. studies can be found in Table 1. According to our evalu-
One study was found by hand-search [16] and, a total ation of clarity and quality of the included studies, by
of 15 full-text articles, were read (Figure 1). We subse- use of the SIGN 50 checklist, eight studies either lack
quently excluded one study that examines CPAP alone powertoconcludeonouroutcomesofinterestorentails
compared to CPAP and standard medical treatment high risk of bias [20-22,24-27,29]. Four studies have ac-
[17]. Another study examines CPAP and medical treat- ceptable power and risk of bias [16,23,28,30]. The clarity
ment given at different time intervals, and not supple- and quality of the studies, according to the SIGN 50
mental CPAP compared to standard medical treatment checklist,isshowninTable2.

PubMed, Embase and Cochrane search
April 2013 and updated January 2014
588 titles excluded
354 - Not regarding NIV or CPAP
228 titles reviewed in Cochrane 86 - Not prehospital setting
290 titles reviewed in Embase 54 - Not acute respiratory failure of any cause
196 titles reviewed in PubMed 45 - Not a clinical trial
34 - Not a controlled design
7 - Not adult patient
8 - Abstract
112 abstracts excluded
4 - Not regarding NIV or CPAP
126 abstracts reviewed 33 - Not prehospital setting
6 - Not acute respiratory failure of any cause
39 - Not a clinical trial
12 - Not a controlled design
0 - Not adult patient
7 - Abstract
11 - Duplications
14 (+ 1 article from
3 articles excluded
hand-search) reviewed
in full text
12 articles met inclusion criteria
Figure1Searchflowdiagram.
Table1CharacteristicsofincludedstudiescomparingstandardmedicaltreatmentwithsupplementaryCPAPorNIV hB
Study CStouudnytry Intervention Studydesign Numberofpatients(N) mCrourdteality Tpyaptieenotfs Poruitmcoamrye Prersimulatry Prervimieawry ttp://wakkee
wt
Cheskesetal.[16] Canada CPAP Obebfsoerrev-aatniodn-aaflt,er 214Interventions 1ra7t/e2s14 cAaRuFseofany Misoneu‐ochtorcotnoasldmpitaiyetr,a(ysl) 7(srpee.9=sc%uo0ln.t8v(d5ssa.))7ry.5% M→ouotrctaolmitye:s w.sjtrem.coal.Scandina
mv
228Controls 17/228 H-LOS: /coian
N/R ntenJourn
ICU-LOS: t/2al
N/R 2o
intubationrate 14.5%vs. IR:→ /1/69fTrau
12.7% m
(p=0.59) a,
R
e
Dibetal. USA CPAP Retrospective, 149Interventions N/R Presumed Prehospitaltreatment 30vs.31min Mortality: su
[27] controlled ACPE times (p>0.01) N/R sc
ita
H-LOS:N/R tio
n
ICU-LOS:N/R a
n
d
238Controls N/R clinicalvariables improvement IR:↓ E
m
intubationrate (p’s<0.01) e
2.6%vs.4.6% rge
(p<0.01) nc
y
M
Ducrosetal.[30] France CPAP Randomized, 107Interventions 8/107 Presumed Combinedcriteria Oddsratio2.1 Mortality: e
controlled ACPE (successful) (1.2-4.0) → dic
multicentre in
H-LOS:N/R e
2
0
ICU-LOS:→ 14
,
100Controls 9/100 Mortality,48hours oddsratio1.4 IR:→ 22
mortality,inhospital (0.4-5.2) :69
Intensivecare oddsratio0.9
unitlength-of-stay (0.4-2.5)
2vs.2days
(p=0.67)
Frontinetal.[28] France CPAP Randomized, 62Interventions 6/60 Presumed Treatmentsuccess Oddsratio1.19 Mortality:
controlled ACPE (0.56-2.53) →
H-LOS:→
ICU-LOS:→
62Controls 7/62 Intubationrate oddsratio1,47 IR:→
hospital (0.23-9.23)
length-of-stay 6vs.6days
Intensive (p=0,5) P
a
careunit 8,2vs.8hours g
e
length-of-stay (p=0,27) 4
mortality, oddsratio o
f
30days 1.14(0.36-3.65) 1
3
Table1CharacteristicsofincludedstudiescomparingstandardmedicaltreatmentwithsupplementaryCPAPorNIV(Continued) hB
Gardtmanetal.[22] Sweden CPAP Obebfsoerrev-aatniodn-aaflt,er 158Interventions 18/158 APrCePsuEmed AadCmPEissaiton 7(p6<%0.v0s0.0913)% M→ortality: ttp://wwakkeet
158Controls 18/158 mortality,1year 2(p2=%0.v6s4.)27% HIC-ULO-LSO:S→: w.sjtremal.Scand
N/A .cin
oa
mv
IR:N/A /cian
o
Garutietal.[25] Italy CPAP Porbosseprveacttiioven,al 35Interventions 1/35 cAaRuFseofany Mortality,adjusted (O0d.0d1s-0r.a5t3io) 0.06 Mortality:↓ ntenJourn
withhistorical t/2al
125Controls 30/125 intubation nointubations H-LOS:↓ 2o
controlgroup rleantegthho-ospf-isttaaly 1(p2<v0s..001081.8)days ICU-LOS: /1/69fTrau
N/A m
a
IR:→ ,R
e
Hubbleetal.[24] USA CPAP Prospective,demographically 120Interventions95 5.35% Presumed Intubationrate Oddsratio Mortality:↓ susc
controlled Controls ACPE 4.04(1.64-9.95) ita
23.15% mortality,inhospital oddsratio7.48 H-LOS:→ tion
hospitallength-of-stay (51.5.986-v2s8..75.46)6days ICU-LOS: and
N/A E
(p=0.755) m
IR:↓ erg
e
Thompsonetal.[23] Canada CPAP Randomized,controlled 35Interventions 5/35 ARFofany Intubationrate Oddsratio Mortality:↓ nc
y
cause 0.16(0.04-0.7) M
e
34Controls 12/34 mortality,inhospital 0.3(0.09-0.99) H-LOS:→ dic
Ilnentegnthsi-voef-csatareyuhnoistpital 69.5vsv.s3.3dadyasys ICU-LOS:→ ine20
length-of-stay IR:↓ 14
,
2
Cravenetal.[29] USA NIV Prospective,demographically 37Interventions 6/37 Presumed Outofhospital 31.4vs.31.2 Mortality:→ 2
:6
controlled ACPE treatmenttime min(p=0.931) 9
25Controls 2/24 improvementinSpO2 13.71%vs.6.99% H-LOS:→
hospitallength-of-stay (p=0.037)
ICU-LOS:
mortality,in-hospital 6.34vs.7.63
N/R
(p=0.48)
6/37vs.2/24 IR:→
(p=0.462)
Roessleretal.[20] Germany NIV Randomized,controlled 25Interventions 1/24 ARFofany Efficiencyof 100%vs.80% Mortality:
cause treatment (p=0.05) →
26Controls 2/25 survival,28days 96%vs.92% H-LOS:→
intensivecareunit (p=1.0)
ICU-LOS:↓
length-of-stayhospital 13.9vs.17.4days
length-of-stay (p=0,5) IR:→
P
intubationrate 1.3vs.3.7days a
g
(p=0.03) e
5
1vs.6 o
(p=0.66) f1
3
Table1CharacteristicsofincludedstudiescomparingstandardmedicaltreatmentwithsupplementaryCPAPorNIV(Continued) hB
Schmidbaueretal. Germany NIV Randomized,controlled 18Interventions 0/18 Presumed Dyspneascore Improvement Mortality:- ttp://wakkee
[21] COPD (p<0.001) wt
18Controls 0/18 roInetsthepenirrsaicvtlieionncicaarraletveariables i(Nmpo=p0dro.i0fvf0ei1nm)ent HIC-ULO-LSO:S→:↓ w.sjtrem.cal.Scandin
unitlength-of-stay otherclinical IR:→ omav
variables /cian
5(p9=v0s..021)85 ontenJourn
Weitzetal.[26] Germany NIV Randomized,controlled 10Interventions 1/10 Presumed SpO2athospital 97.3%vs.89.5% Mortality: t/2al
13Controls 1/13 ACPE acldinmiciasslivoanriables N(po=0d.i0ff02) →H-LOS:→ 2/1/69ofTrau
m
Ilnentegnthsi-voef-csatareyunit c1l.i7ni±ca0l.5vavsri.a2b.3les±0.6 ICU-LOS:→ a,R
hospitallength-of-stay days8.2±2.3vs.12.5 IR:N/A esu
±1.8days sc
ita
Allcomparisonsareinterventionvs.control.Arrowsshowing;nodifference→,improvement/reduction↓. tio
(Continuouspositiveairwaypressure,CPAP;Positivepressureventilation,PPV;Acuterespiratoryfailure,ARF;Acutecardiogenicpulmonaryedema,ACPE;Chronicobstructivepulmonarydisease,COPD;Intubationrate, n
IR;Mortalityin-hospital,IHM;Oxygensaturation,SpO2;Respirationrate,RR;Clinicalvariables,CV;NotAvailable,N/A;NotReported,N/R;HospitalLengthOfStay,H-LOS;IntensiveCareLengthOfStay,ICU-LOS. an
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Table2Clarityandqualityoftheincludedstudies hB
Study eCtheasl.kes Detibal. Detuaclr.o[s30] Fertoanl.tin Getaardl.tman Getaarul.ti[25] Hetuablb.l[e24] Tethoaml.pson Cetraavl.e[n29] Retoeasl.s[le2r0] Secthaml.iedbauer Weteaitl.z ttp://wwakkeet
1ad.1dTrehsesesstuadnyappropriate [••1••6] [••27] •••• [••2••8] [••2•2] •••• •••• [••2••3] •••• •••• [••21] [••2•6] w.sjtremal.Scand
andclearlyfocusedquestion .coina
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1.2Theassignmentofsubjects NA NA ••• •••• NA NA NA ••• NA •••• •••• ••• /cian
t1aod.3etArqenuaatmteecnotngcreoaulmpsenratndomised NA NA • •••• NA NA NA •••• NA •••• •••• • ontent/2Journal
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1.5Thetreatmentandcontrol ••• •• •••• •••• ••• •• •• ••• •• •••• ••• •• susc
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1.6Theonlydifferencebetween ••• •• •••• •••• •• •• •• ••• ••• •• •••• •• an
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1.7Allrelevantoutcomes •••• ••• ••• ••• •• ••• ••• •••• •••• ••• ••• ••• rge
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1.8Whatpercentageofthe 00 4/ 11/10713/ 0/622/ 00 NRNR 10/12024/ 1/351/36 9/71in 2/51in 1/180/18 0/13 ic
individualsorclustersrecruited 14911/ 100 62 95 total total 0/10 ine
intoeachtreatmentarmofthe 238 2
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studydroppedoutbeforethe 1
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2
1.9Allthesubjectsare ••• NA •••• •••• •••• NA •••• •••• •• ••• • ••• :69
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1.10Wherethestudy NA •• ••• NA NA NA •• NA NA NA NA NA
iscarriedoutatmore
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Table2Clarityandqualityoftheincludedstudies(Continued) hB
thanonesite,results ttp://wakkee
arecomparableforallsites wt
2st.1udHyodwonweeltlowmasintihmeisebias? + - ++ ++ - - - + - + + - w.sjtremal.Scand
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Bakkeetal.ScandinavianJournalofTrauma,ResuscitationandEmergencyMedicine2014,22:69 Page9of13
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CPAP trend toward decreased intubation rate with supplemen-
In the eight studies comparing supplemental CPAP to talprehospital NIVisseen[20,21],seeTable3.
standard medical treatment alone, the number of pa-
tients in the intervention groups ranges between 35 and Discussion
214 [16,22-25,27,28,30]. Three studies are randomized Ourprincipalfindingsare:1)Oneoffourstudiesofaccept-
controlled trials [23,28,30]. One study is prospective but able quality shows a lower mortality and intubation rate
not randomized [24]. Three studies are before and after with supplemental prehospital CPAP compared to stand-
studies [16,22,25]. One study is a cross-sectional study, ard medical treatment alone, and the remaining three are
where outcomes of patients receiving CPAP are com- neutral.Atrendtowardlowerintubationratewithsupple-
pared to outcomes from those not receiving this inter- mentalprehospitalCPAPisseenintwostudies.2)Thereis
vention [27]. In three studies comparing supplemental insufficientevidencetoconcludeontheuseofsupplemen-
CPAP to standard medical treatment alone, a reduction talprehospitalNIV.
in mortality is found [23-25]. No studies show a signifi-
cant increase in mortality with administration of CPAP. CPAP
One study shows a lower H-LOS [25] and another study All the included studies are relatively small, and many
reports no difference in H-LOS [22]. Three studies re- lack the powerto investigate hard endpointslike mortal-
port no difference in ICU-LOS [23,28,30]. Intubation ity. Three studies did indeed find a reduced mortality
rate is reduced with supplemental CPAP treatment in [23-25], but two studies had problems with the study
three studies [23,24,27]. According to our evaluation of design [24,25]. The risk of type two statistical errors in
clarity and quality of the studies, four studies either lack theincludedstudiesishigh.
power to conclude on our outcomes of interest [25] or In the study by Cheskes et al. a trend towards in-
entail high risk of bias [22,24,25,27] and were excluded creased mortality in the subgroups chronic heart failure,
from contribution to our conclusion. Four studies have COPD and pulmonary edema was seen, but this was not
acceptable power and risk of bias [16,23,28,30]. Of these, foundintheotherstudiesandtheirresultwasnot statis-
onesmallerrandomizedcontrolledtrialshowsareduction tically significant[16].
in both mortality and intubation rate [23]. The remaining Prehospital CPAP given as a supplement to standard
three – one large descriptive study and two randomized medical treatment improves clinical endpoints like re-
and controlled studies show no effect on any of our out- spiratory rate and arterial saturation [24,25,27], when
comes of interest [16,28,30], but there is a trend toward comparedtostandardmedical treatment alone. Instudies
lowerintubationratewithsupplementaryCPAPin two of wherearterialgasesweretaken,animprovementwasseen
these studies [28,30]. The prehospital, inhospital, and [25,30]. PaO improved and pH was higher in the inter-
2
overallintubationratesareshowninTable3. vention group in one study [25]. The other study showed
lower PCO and normalization of pH, but did not report
2
NIV on PaO as an endpoint [30]. These findings, combined
2
In the four studies comparing supplemental prehospital withthelowerintubationrate[23]andtrendtowardlower
NIV to standard medical treatment alone, the number of intubation rates [28,30], indicate that CPAP may reduce
patients in the intervention groups ranges between 10 prehospital intubation rates, but this needs to be verified.
and 37 [20,21,26,29]. Three of the studies have a ran- Whether or not this is beneficial, cannot be answered
domized and controlled design [20,21,26]. The fourth basedonthecurrentevidence.
study is a prospective controlled study with five rescue Ofthefourstudieswithacceptablequality,twoincluded
units administering bi-level positive airway pressure as patientswithacuterespiratoryfailureofanycause[16,23]
intervention group and five units administering standard and two included patients with ACPE [28,30]. The low
medical treatment alone as control group [29]. There numberofstudiesdoesnotallowustoconcludeondiffer-
was no difference in mortality with supplemental NIV encesbetweentheconditionsbeingtreatedfor.
compared to standard medical treatment alone. In two
studies, a reduction in ICU-LOS is found [20,21]. One NIV
study reports no difference in ICU-LOS [26]. No differ- Thereis insufficient evidence to conclude on the effect of
ence in total H-LOS is found in any of the studies. No supplementalprehospitalNIVcomparedtostandardmed-
difference in intubation rate is shown in any of the stud- ical treatment alone. The failure to demonstrate differ-
ies. According to our evaluation of clarity and quality of ences in mortality, intubation rate, and H-LOS could be
evidence, all four studies lack power to make conclu- causedbytypetwoerrorsinthesesmallstudies.Thusthis
sions on our outcomes of interest [20,21,26,29] and two does not mean that the strategy should be abandoned in
studiesentailhigh riskof bias[26,29].In two smallstud- future research. Studies in patients with COPD indicate
ies with low risk of bias, a reduction in ICU-LOS and a that CPAP decreases inspiratory work of breathing [31].
Bakkeetal.ScandinavianJournalofTrauma,ResuscitationandEmergencyMedicine2014,22:69 Page10of13
http://www.sjtrem.com/content/22/1/69
Table3IntubationrateswithsupplementalprehospitalCPAP/NIVcomparedtostandardmedicaltreatmentalone
Study SupplementalprehospitalCPAP/NIV Standardmedicaltreatmentalone
CPAP
Cheskesetal.2013 31/214 30/228
Prehospital 0/124 1/228
Inhospital 31/214 29/228
Ducrosetal.2011 3/107 6/100
Prehospital NA NA
Inhospital NA NA
Frontinetal.2011 2/60 3/62
Prehospital 0/60 1/62
Inhospital 2/60 2/62
Thompsonetal.2008 7/35 17/34*
Prehospital 0/35 9/34
Inhospital 7/35 8/34
Dibetal.2012 NA NA
Prehospital 4/149 11/238*
Inhospital NA NA
Gardtmanetal.2000 NA NA
Prehospital NA NA
Inhospital NA NA
Garutietal.2010 0/35 14/125
Prehospital 0/35 14/125
Inhospital 0/35 0/125
Hubbleetal2006 10/120 24/95*
Prehospital 5/120 7/95
Inhospital 5/120 17/95
NIV
Cravenetal2000 4/37 7/25
Prehospital 0/37 6/25
Inhospital 4/37 1/25
Roessleretal2011 1/24 6/25
Prehospital 0/24 1/25
Inhospital 1/14 5/25
Schmidbaueretal2011 3/18 7/18
Prehospital 1/18 0/18
Inhospital 2/18 0/18
Weitzetal2007 NA NA
Prehospital NA NA
Inhospital NA NA
*=statisticalsignificantdifference.Studiesratedashavingacceptablesizeandqualityarebold.
The addition of pressure support ventilation to positive when NIV is used. Arterial saturation significantly im-
end expiratorypressure, increasestidal volume in propor- proveswithsupplementalNIVcomparedtostandardmed-
tion to the amount of pressure applied and theoretically ical treatment alone, including high fractions of inspired
relives inspiratory muscles [32]. Thus theoretically, NIV oxygen, in three of the studies included in this review
should be advantageous and in all of the included studies [20,26,29].Inthefourthstudy,improvementinarterialsat-
measuring these, vital signs like respiratory rate improve uration was more pronounced in the intervention group,