cleveland clinic journal of medicine 2009 mireles cabodevila 417 30

8/2/2019 Cleveland Clinic Journal of Medicine 2009 MIRELES CABODEVILA 417 30

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EDUARDO MIRELES-CABODEVILA, MDDepartment o Pulmonary and Critical Care Medicine,University o Arkansas or Medical Sciences,Little Rock, AR

Alternative modes o mechanicalventilation: A review or the hospitalist

ABSTRACT

Newer ventilators can be set to modes other than the

pressure-control and volume-control modes o older ma-chines. In this paper, the authors review several o thesealternative modes (adaptive pressure control, adap-tive support ventilation, proportional assist ventilation,airway pressure-release ventilation, biphasic positiveairway pressure, and high-requency oscillatory ventila-tion), explaining how they work and contrasting theirtheoretical benets and the actual evidence o benet.

KEY POINTS

The alternative modes o ventilation were developedto prevent lung injury and asynchrony, promote betteroxygenation and aster weaning, and be easier to use.However, evidence o their benet is scant.

Until now, we have lacked a standard nomenclature ormechanical ventilation, leading to conusion.

Regardless o the mode used, the goals are to avoidlung injury, keep the patient comortable, and wean thepatient rom mechanical ventilation as soon as possible.

CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 76 NUMBER 7 JULY 2009 417

Technologic advances mputr-z tr m ttr

m t pb t r ttry

t w m. Dr t -t t r t prt ttr-u u jury, mpr ptt mrt, brt t ptt rm m -tt pb.

W t t trtm t rtt tm rm t pum-tr prur-tr m.Sm rry u t w m,but m m tr ty bmt mt mm u, r r b uukwy (t prtr murt

t m m). T rmt w pr t m tt by m rmt tr u, but rtr tt p t urt tr py-, trt, t.

W u tw :Exp wt t m Bry rw t trt bft t tu upprt t tr-t m tt.

STANDARD NOMENCLATURE NEEDED

S t t, m tt b pu by mutp m b ut rb t m t. Fr xmp, -um-tr tt um-y tt, t-tr tt,um-mt tt, trm tt. Smry, mutpbbrt r u, p tbr ttr, w rym b rt yr w m

b p. T t umbr m

REVIEW

*Mr. Chatburn has disclosed that he has received ees rom Cardinal Health or serving onadvisory committees or review panels and rom Strategic Dynamics Inc or consulting.

doi:10.3949/ccjm.76a.08043

ENRIQUE DIAZ-GUZMAN, MDRespiratory Institute,Cleveland Clinic

GUSTAVO A. HERESI, MDRespiratory Institute,Cleveland Clinic

ROBERT L. CHATBURN, BS, RRT-NPS*

Respiratory Institute, Respiratory Therapy Section,Cleveland Clinic

Abbreviations used in this articleAPCadaptive pressure controlAPRVairway pressure-release ventilationASVadaptive support ventilationCPAPcontinuous positive airway pressureFio2raction o inspired oxygenHFOVhigh-requency oscillatory ventilationPAVproportional assist ventilationPEEPpositive end-expiratory pressurePSVpressure support ventilation

EDUCATIONAL OBJECTIVE: Readers will be able to explain what some o the new ventilator modes doand their theoretical and actual benetsCREDIT

CME


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418 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 76 NUMBER 7 JULY 2009

MECHANICAL VENTILATION

m u t mt - rt r py.

Ert t tb mm m-tur r ur wy.1

WHAT IS A MODE?

A m m tt trt mpt:

T tr rbT brt quT trt m.Smr m my rqur mr t

rpt t tu tm, but t but b xp by t tr m-pt.

The control variableI r, prt t pr,r by t ptt rt, t ttr, rbt, w xprt p. Fr mp-ty, t rt m brt mt prtry p t brt.

T m y tr t um( w) r t prur . T brt b urtr rb t b wttrr t brt, wt mt t (t mx-

mum u tr rb), wt

(y) t.Trr, um-tr brt

trr by t ptt r by t m,mt by w, y by um (FIGURE1). A prur-tr brt trr byt ptt r t m, mt by pr-ur, y by tm r w (FIGURE 1).

The breath sequenceTr r tr pb brt qu:

Ctuu mtry tt, w brt r tr by tm (but b trr by t p-tt)Itrmttt mtry tt, w t ptt tk ptubrt btw mtry brtCtuu ptu tt, w brt r ptu (TABLE 1).

The targeting schemeT trt r bk m rr tt ttr tt prrmm tttt t rp t t ptt u m-p, u rt, rprtry rt.T rut b mp trt prur prur-tr m, r t

b b mpt rtm.

The mode

name can be

misleading

Tidal volumeset by operator

Inspiratory pressureset by operator

Airwaypressure

Patienteffort

Larger respiratoryeffort

Small respiratoryeffort

No respiratoryeffort

Volume

Flow

FIGURE 1. Volume control (top) and pressure control (bottom) are modes o continuous mandatoryventilation. Each mode is depicted as patient eort increases. Notice that the modes control variable(volume or pressure) remains constant as patient eort increases. Contrast these ndings with thosein FIGURE 2.

Volume control

Pressure control


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MIRELES-CABODEVILA AND COLLEAGUES

I t t tt w, w rb m t b trt m m- tt. W w xp y t tr-t m t m rw (TABLE 1,TABLE 2), but mr rmt tr trt- m b u wr.1,2 W wu rt ut pttr m tt.

ADAPTIVE PRESSURE CONTROL

O t r wt prur-tr -tt tt t t urt mmum

mut tt (t um r tt

ut 1 mut; t t um brt pr mut) t u m r ptt rt, r bt. T t prbm, 1991 t Sm Sr300 ttr (Sm, Mqut Crt CrAB, S, Sw) tru Prur R-ut Vum Ctr, m tt rprur-tr brt wt trt tum tt trw kw p-t prur tr (APC) (FIGURE 2).

Other names or adaptive pressure controlPrur Rut Vum Ctr (M-

qut Sr-, Rttt, Grmy)

A mode

o ventilation

is only as good

as the operator

who applies it

TABLE 1

Mechanical breath terminology

Mechanical breath descriptionControl variablethe mechanical breath goal, ie, a set pressure or a set volume

Trigger variablethat which starts inspiration, ie, the patient (generating changes in pressure or fow)or a set rate (time between breaths)

Limit variablethe maximum value during inspiration

Cycle variablethat which ends inspiration

Breath sequenceContinuous mandatory ventilationall breaths are controlled by the ventilator, so usually they have thesame characteristics regardless o the trigger (patient or set rate); no spontaneous breaths are allowed

Intermittent mandatory ventilationa set number o mechanical breaths is delivered regardless o the

trigger (patient initiation or set rate); spontaneous breaths are allowed between or during mandatorybreaths

Continuous spontaneous ventilationall breaths are spontaneous with or without assistance

Tpe o control or targeting scheme a

Set pointthe ventilator delivers and maintains a set goal, and this goal is constant (eg, in pressurecontrol, the set point is pressure, which will remain constant throughout the breath); to a degree, all modeshave some set-point control scheme

Servothe ventilator adjusts its output to a given patient variable (ie, in proportional assist ventilation,the inspiratory fow ollows and amplies the patients own fow pattern)

Adaptivethe ventilator adjusts a set point to maintain a dierent operator-selected set point (ie, in

pressure-regulated volume control, the inspiratory pressure is adjusted breath to breath to achieve a targettidal volume)

Optimalthe ventilator uses a mathematical model to calculate the set points to achieve a goal (ie, inadaptive support ventilation, the pressure, respiratory rate, and tidal volume are adjusted to achieve a goalminute ventilation)

a Mentioned in this review; or more inormation, reer to Chatburn1


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AutFw (Drr M AG, Lbk,Grmy)Apt Prur Vtt (HmtG, Hmt M AG, Buz,Swtzr)Vum Ctr+ (Purt Btt, TyHtr; Mf, MA)Vum Trt Prur Ctr, Pr-ur Ctr Vum Gurt (E-

trm, Gr Etr, M, WI).

What does adaptive pressure control do?T APC m r prur-trbrt wt pt trt m(TABLE 2).

I prur-tr tt, t -um p t u py m- (mp rt) pttrt (FIGURE 1). Trr, t t umr wt u pyy (,

rr r mr t um t trt).

Mechanical

breaths can be

delivered only

via pressure

control or

volume control

TABLE 2

Classifcation o modes o ventilation

CONTROL VARIABLE BREATH SEQUENCE TARGETING SCHEME EXAMPLES O COMMERCIALLy AVAILABLE MODES

Volume Continuousmandatoryventilation

Set point Volume control, VC-A/C, CMV, (S)CMV,Assist/Control

Dual CMV + pressure limited

Adaptive Adaptive fow

Intermittentmandatoryventilation

Set point SIMV, VC-SIMV

Dual SIMV + pressure limited

Adaptive AutoMode (VC-VS), mandatory minute volume

Pressure Continuousmandatory

ventilation

Set point Pressure control, PC-A/C, AC PCV,high-pressure oscillatory ventilation a

Adaptive Pressure-regulated volume control, a VC+AC a,AMV+AutoFlow a

Intermittentmandatoryventilation

Set point Airway pressure-release ventilation, aSIMV PCV, BiLevel, a PCV+ a

Adaptive VC+SIMV, V V+SIMV APVSIMV,SIMV+AutoFlow, Automode (PRVC-VS)

Optimal Adaptive support ventilation a

Continuousspontaneousventilation

Set point Continuous positive airway pressure,pressure support

Dual Volume assured pressure support,

volume augmentServo Proportional assist ventilation, a automatic

tube compensation

Adaptive Volume support

Intelligent SmartCare

Three levels o classication o the modes o mechanical ventilation. As noted in the text, or a given combination o control vari-

able, breath sequence, and targeting scheme, several commercial mode names are described. Each commercial mode name can

have subtle dierences rom others in the same class; however, the main characteristics o the mode can be determined by this

classication.a Discussed in this paper

CMV = continuous mandatory ventilation, CSV = continuous spontaneous ventilation, IMV = intermittent mandatory ventilation,

SIMV = synchronized intermittent mandatory ventilation


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T rm t t, m APCm jut t prtry prur t rt t mm trt t um. I t -um r, t m r t -prtry prur, t um r,t m r t prtry prur.Hwr, t ptt rt r u,t t um w r pt r- t prtry prur (FIGURE 2). T jut-mt t t prtry prur ur tr tt um -trt umbr brt.

Common sources o conusionwith adaptive pressure controlFrt, APC t um-tr m. Ium tr, t t um t; APC t t um rr r, t ttr w jut tt prur t t trt um.Tu, APC urt r mmumt um but t mxmum t um.

S, rtrt prur -tr ( , APC) tt t w r t mt tt rwy prur(, mt t t prtry prur).T rtrt w ptt w -rt prtry rt t r w

m, w ky mr mrtb.

T ty rt rm um -tr, w w t by t prtr fx. Tu, t ptt rt tr u (FIGURE 1), t t wt w yry, w t ptt t t t w k r brt.

Ventilator settingsin adaptive pressure controlVttr tt APC r:

T umTm pt prt (prtry tm)FrquyFrt pr xy (F o2)Pt -xprtry prur (PEEP).Sm ttr rqur tt t

p t r t pk prur ( kw p prt r prtry r tm).

Clinical applicationso adaptive pressure controlT m t mt -tt t um ur prur-trtt t prmt prtry wyry. It m utmty r-u ttry upprt (, w) t ptt prtry rt bm tr-

r, wk rm t.

The response o

the ventilator

to the patient is

regulated in a

number o ways

Target tidal volumeset by operator

Target tidal volumeset by operator

Inspiratory pressure isadjusted to maintaina target tidal volume

Larger respiratory

effort

Small respiratory

effort

No respiratory

effort

Airway

pressure

Patienteffort

Volume

Flow

Pressure

FIGURE 2. A machine in adaptive pressure control mode (top) adjusts the inspiratory pressure to main-tain a set tidal volume. Adaptive support ventilation (bottom) automatically selects the appropriatetidal volume and requency or mandatory breaths and the appropriate tidal volume or spontaneousbreaths on the basis o the respiratory system mechanics and the target minute ventilation.

Adaptive support ventilation

Adaptive pressure control


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APC adjusts

the inspira-

tory pressure

to deliver the

set target tidal

volume

APC my t b r ptt w pprprty r rpr-try r (, r mtb ), t prtry prur w r t

mt t trt r t um,pprprty t t wrk brtt t ptt.

Theoretical beneftso adaptive pressure controlAPC urt mmum r t -um (u t prur rm tr tt w, tt t trt t um tr). Otr trt bft r wyry, ttr mput by tprtr, utmt w ttr

upprt.

Evidence o benefto adaptive pressure control Physiologic benefts. T m wrpk prtry prur t um-tr tt,3,4 w t rprt pt f. Hwr, um-tr m (t uu mprtr), tpk prtry prur mtt bt rt mp. H, pkprtry prur xpt t b rbut t rt tu u-tprur. It t ptu prur, m-tt u mp, tt rt tu jury. Patient comort. APC my r twrk brt w u w t -um tt w tr rrprtry rt (r).5 Itrty, APCw mrtb t prur upprttt m tr.6

Outcomes t b tu.7

Adaptive pressure control: Bottom lineAPC wy b wy u,mtm ukwy (, t prtrtk t um tr). It rtyy t u t t; wr, tbft t.

ADAPTIVE SUPPORT VENTILATION

Apt upprt tt (ASV) rm mtry mut tt

mpmt wt pt prur tr.

Mtry mut tt m ttw t prtr t prt trt muttt, t ttr t uppmtry brt, tr um- r pr-

ur-tr, t ptt ptubrt rt wr mut tt.

ASV utmty t t pprpr-t t um rquy r mtrybrt t pprprt t um rptu brt t b t rp-rtry ytm m trt mutr tt.

Drb 1994 by Lubr t ,8,9ASV bm mmry b 1998 Eurp 2007 t Ut Stt(Hmt G ttr, Hmt M-

AG). T t frt mmry -b ttr tt u ptm trt- m ( bw).

What does adaptive support ventilation do?ASV r prur-tr brt u- pt (ptm) m (TABLE 2).Optm, t txt, m mmzt m wrk brt: t m- t t um rquy ttt ptt br wu prumby t t ptt wr t t t t-tr. T pttr um t ur tptt t rt ptu brt.

T ttr ut t rm r-qur mut tt b t p-tt wt tmt pum (, 2.2 mL/k). T utrprt 100% mut tt. T t t b t trt prt mut tt tt t ttr wupprtr t 100% t ptt r rqurmt u, , t p r -r p, r t 100% urw.

T ttr ty r ttbrt, w t mur t xprtrytm tt r t rprtry ytm t u t wt t tmt p rm mut tt t u-t ptm brt rquy trm m wrk.

T ptm r trt t um u-t t rm mut tt - by t ptm rquy. T trt t

um by t u APC (


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b) (FIGURE 2). T m tt t prurmt utmty jut t r r t um qu t ttrt. T ttr tuuy mtr

t rprtry ytm m jutt tt ry.

T ttr jut t brt t r trpp by w u tm t x-, t yptt by rt um rtr t t p, t utrum by r tum.

Ventilator settingsin adaptive support ventilationVttr tt ASV r:

Ptt t (t ut t bywt)SxPrt rm prt mut -tt F o2PEEP.

Clinical applicationso adaptive support ventilationASV t m t-t, rm t upprt t w.

Theoretical beneftso adaptive support ventilationI try, ASV r utmt t ttr tt, utmt ptt t ptt u m, r um mput t m, m-pr yry, utmt w.

Evidence o benefto adaptive support ventilation

Physiologic benefts.Vttr tt

r jut utmty. ASV t -rt t um-rprtry rt mb-t b rprtry m p pryz ptt.1012 I ty brt- ptt, tr w r tttr tt by ASV r r-t r ( u pyy).10Cmpr wt prur-tr trmt-tt mtry tt, wt ASV, tprtry ptt-ttrtrt bttr.13

Patient-ventilator synchrony and com-

ort t b tu. Outcomes. Tw tr ut ttASV my r tm mtt.14,15 Hwr, tr tr,16

mpr wt tr prt, ASV t wr ttr jutmt but mr ptur w utm. Tt t m t t rt tb xm.17,18

Adaptive support ventilation: Bottom lineASV t frt mmry b mtt utmty t t ttrtt xpt PEEP Fio2. T mpprprt r rt r ptt wt pr rprtry rt r

pryz ptt. E t t ty brt ptt utmu t ty r t t k-.

PROPORTIONAL ASSIST VENTILATION

Ptt w rm rprtry rbut w futy ut qutptu tt r t ubjtt prur upprt tt (PSV), w t ttr rt ttprur truut prt rr t tty t ptt rt.

I 1992, Yu u19,20 -p prprt t tt (PAV) trt w t ttr -rt prur prprt t t pttrt. PAV bm mmry b Eurp 1999 w ppr tUt Stt 2006, b t Pur-t Btt 840 ttr (Purt BttC, Bur, CO). PAV b u r tt, but t t -b t Ut Stt.

Other names or proportionalassist ventilationPrprt Prur Supprt (Drr M-; t yt b t Ut Stt).

What does proportionalassist ventilation do?T m r prur-trbrt wt r tr m (TABLE 2).

T bttr urt PAV, w mpr

APC

is not a

volume-

controlled

mode


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ASV selects

a tidal volume

and requency

that the

patients

brain would

presumably

select

t wt PSV. Wt PSV, t prur pp byt ttr r t prt tt tt ( t-pt m) ut yrtr ( prt t mxmum prt-ry w u) r. T prtry w t um r t rut t pttprtry rt, t prur pp, t rprtry ytm m.

I trt, ur PAV, t prur pp ut ptt rt: t rtr tprtry rt, t rtr t r p-p prur (r trt m) (FIGURE3). T prtr t t prt upprtt b r by t ttr. T t-tr trmttty mur t mp rt t ptt rprtry ytm t ttu ptt-rt w um, t b t t r prprt mut prtry prur.

I PAV, PSV, brt r pt-u (TABLE 1). T ptt tr t tm z t brt. Tr r prt pr-ur, w, r um , but ty mt t um prur r b t.

Ventilator settingsin proportional assist ventilationVttr tt PAV r:

Arwy typ (tr tub, tr-tmy)Arwy z (r mtr)Prt wrk upprt (t r5%95%)T um mtPrur mt

Exprtry tty (rmy, p-

rt , w u tp; t prm-tr t t ttr t wt w t prt).

Caution when assessing the literature.Err ttr r, , Drr M-tb (Urty Mtb, Wp, MB,C), w r t b t UtStt, rqur t rpt ut trprtry ytm m t mutt w um t (mpfttr) pty. T rm t m-tt, w twr utmty jut tw um mpft t upprt t mp by t utmty muru rt t (r mp) t rprtry ytm.21 Ttwr u t m (Purt B-tt) b t Ut Stt.

Clinical applicationso proportional assist ventilationT PAV m t r mxmzttr ptt yry r t p-tu tt.

PAV trt ptt wtrprtry pr (bryp) r r rk (, brpur ftu). It ub u wt ut ptt wt ryprt, w t ptt my tb x but t ttr t r-z t. Atr rup w PAV ub u wt ut t wt -ttry r, w t ttr r-tmt rprtry ytm m. Ttut t rt u t t

ruwy pm, w t t-

Ventilator measuringrespiratory system

characteristics

Flow, pressure, and volume deliveredby the ventilator are adjusted

proportionally to patient effort

Patienteffort

Volume

Flow

Pressure

FIGURE 3. In proportional assist ventilation, the fow, pressure, and volume delivered are adjustedproportionally to the patients eort.

Proportional assist ventilation


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In PAV, the

greater the

inspiratory

eort, the

greater the

increase in

applied

pressure

tr tu t pr upprt tptt tpp prt.22

Theoretical benefts

o proportional assist ventilationI try, PAV u ru t wrk brt, mpr yry, utmtypt t ptt u m rt, r t r ttr tr-t mput, r t r t, mpr p.

Evidence o benefto proportional assist ventilation Physiologic benefts. PAV ru t wrk brt bttr t PSV,21 t

rprtry m r -r rprtry m (yprp).2325T mym prf mr t tt PSV. T um r rb; wr, rt rprt t t um wr wtt u-prtt r (68 mL/k, ptuprur < 30 m H20).

26,27

Comort. PAV t ptt rt mrt tt PSV .23,25 PAV -fty ru yry,27 w turmy rby t p rty p-tt.28

Outcomes. T prbbty ptubrt wtut t w ftybttr rty ptt tt wtPAV t wt PSV. N tr rprt tt PAV t.27,29

Proportional assist ventilation: Bottom lineExt b rr b wtPAV rt rm rprtry ur,u btrut u , ut rpr-try tr yrm (ARDS), r r-prtry ur. It uf t m , w t mpr ptt-ttr yry. C- xpr wt PAV t Ut Stt mt, t w y rty ppr.

AIRWAy PRESSURE-RELEASEVENTILATION ANDBIPHASIC POSITIVE AIRWAy PRESSURE

Arwy prur-r tt (APRV)w rb 1987 by Stk t 30 m r r tt ut u

jury w rwy prur.

APRV mb tt pt rwyprur (mpr xyt prmt- r rrutmt) wt trmtttr (u xt).

I 1989, Bum t 31 rb bp- pt rwy prur tt m w ptu tt ub t y pt t mtt yprt r xt(FIGURE 4). T w t w urtrtptu brt t ru t prmt w. T m r ptu-y t m, t m r b ttt tm pt w prur (T w; b-w) t 1.5 r APRV. Otr-w, ty t rtrt, tu

w y ttr wt t pbty r APRV t r bp p-t rwy prur, r. Mwt t m bm mmry -b t m 1990.

Other names or biphasic positive airwapressureOtr m r bp pt rwy pr-ur r:

BL (Purt Btt)BIPAP (Drr Eurp)B Vt (Sm)BP (A, Cr Ht, I,Dub, OH)PCV+ (Drr M)DuPAP (Hmt).

Cautionname conusion. I NrtAmr, BPAP (Rpr, Murry,PA) BL r u t rr t - m tt.

APRV tr m.

What do these modes do?T m r prur-tr,tm-trr, tm-y brt u- t-pt trt m (TABLE 2). Tm tt t ttr mt -tt prur (t pt) t ptu brt. Cautionsource o conusion. T trmtuu pt rwy prur (CPAP) t u t rb t m. Hwr,CPAP prur tt pp tuuyt t m ; t ptt rt

t wrk t mt tt (prur-


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tr tuu ptu t-t t urrt mtur). I APRV,t rwy prur trmttty r rpp, rt t um ttupprt tt. I tr wr, t prur-tr brt wt ry pr- prtry tm rt xprtrytm w ptu tt p-b t y pt (prur-tr tr-mttt mtry tt t urrtmtur).

Hw t m r t t ttrmy b ur u. T rbt tm pt w rwy pr-ur, w u t trm T

T

w, rp-

ty. By t, t r btwAPRV bp m t urt Tw (< 1.5 r APRV).

Smry, P Pw r u t rbt w rwy prur. T bttr u-rt t pt, yu rt t mm t prur-tr t-t by tk t T t prtrytm, t Tw t xprtry tm, t P prtry prur, t Pw PEEP.

H, APRV xtrm rm -

r rt tt, wt prt-t-

xprt rt 4:1. T m pttp mt t tm P T, xt r rt (Tw Pw). I -trt, t bp m u tprt-xprt rt (FIGURE 4).

A wt y rm prur tr, tt um rt by rwy prurr b b (, t -xprtryu). H, t ur r muttt, t mtry brt rt mutb r (, r T, Tw, r bt)r t t um mut b r (, -r t r btw P Pw).T m tt APRV t Tw t p-p mr t (by r t umbr brt) r b mr pr (w mrr t x). Bu urtrt pt-u brt r prmtt t y pt ty, t ptt trbut t t tt m-ut tt (uuy 10%40%).

I APRV bp m, t pr-tr t tm prur prt xprt w b r rr tptt brt rtt ptt p-tu brt t trr mbrt. Sm ttr utmt -

jutmt t mpr t trr yry.

Spontaneous breaths occurat any point without altering

the ventilator-deliveredbreaths

Thigh

:Tlow

= 4:1Phigh

and Thigh

Plow

and Tlow

Thigh

:Tlow

= 1:14Phigh

and Thigh

Plow

and Tlow

Volume

Pressure

FIGURE 4. Airway pressure-release ventilation (top) and biphasic positive airway pressure (bottom)are orms o pressure-controlled intermittent mandatory ventilation in which spontaneous breathscan occur at any point without altering the ventilator-delivered breaths. The dierence is that thetime spent in high pressure is greater in airway pressure-release ventilation.

Biphasic positive airway pressure

Airway pressure-release ventilation

APRV allows

spontaneous

breaths at any

point in the

cycle


11/14



Ventilator settingsin APRV and biphasic modeT m rqur t tt tw prur (P Pw) tw tm urt

(T Tw). O prur upprtr utmt tub mpt t t p-tu brt. T r Tw r-t r t T:Tw rt: APRV rt Tw ( prt-xprt r-t 4:1). Bp m tprt-xprt rt 1:1 t 1:4.

Clinical applications APRV u ut u jury ARDS. T m u b u wt u-t r t t ptt wt btrut

u r pprprty r r-prtry r.3235

Biphasic mode t r bt t-t w. I ptt w prrprtry rt r w pryz, bp- t t prur-tr/tuumtry tt.

Theoretical beneftso APRV and biphasic modeMutp bft b rb t tm. I try, APRV w mxmz mt r rrutmt, mpr xy-t, wr t prur, rrt. Bt APRV bp, by pr-r ptu brt, w mprtt-pru mt u,mpr t mym prf ( rprr, r r utput, ru -trur wrk, mpr r pru), mpr yry (r t wrk brt t r t).

Evidence o beneft o APRVand biphasic modeAPRV bp r rt m.Hwr tu ut tr t rmb. T prt t rut t -mtur u rt prt rt utr.36

Physiologic benefts. I tu, pt-u brt trbut t 10% t 40% mut tt,37,38 mpr tt pt r t u, mpr -tt-pru mt rrutmt,39

mpr mym prf.40

Patient comort. T m rtut t r t r t,38 but rt tr w r wt prur-tr trmt-

tt mtry tt.41 Ptt t-tr yry mrt t btu.32,42

Outcomes. I m tr, t mm r trm t, butty my r t t mtt.38,41,43,44

APRV and biphasic mode: Bottom lineMt ptu brt w m tt mym ttry bft.

APRV bp m r t t mt. APRV m t mxmz mrwy prur , , u rrutmt,wr t m t bp m yry.

Tr ptr ttr tt qut rt t py t.33,34,36

Atu t m r wy u m tr, tr yt ttty r uprr t t um- rprur-tr tt wt w t -um r ARDS ut u jury. Tr u tt t m m-pr yry, tm t w, r pttmrt.

HIGH-REQUENCyOSCILLATORy VENTILATION

H-rquy try tt(HFOV) w frt rb ptt 1952 by Emr w y p t ry 1970 by Lukmr.45

T HFOV t mmz ujury; t rtrt (u bw)mk t uu ptt wt r ARDS.T US F Dru Amtrt p-pr t r t 1991 r r 1995. T ut m b b 1993, but t w t ppr ut 2001(SrM 3100B, Cr Ht, I).

Other names or high-requencoscillator ventilationW HFOV trt m, t

w rym rb mr m:

Maintaining

spontaneous

breathing while

on mechanical

ventilation has

benefts


12/14



HFPPV (-rquy pt prurtt)HFJV (-rquy jt tt)HFFI (-rquy w trrupt)HFPV (-rquy pru t-t)HFCWO (-rquy t w -t).A t m rqur rt p-

z ttr.

What does high-requencoscillator ventilation do?Cptuy, HFOV rm prur-tr trmttt mtry t-t wt t-pt tr m. Itrt t t prur-trtrmttt mtry tt, wrty m ptu brt my buprmp rty r mtrybrt, HFOV uprmp ry m m-try brt (t) tp pt-u brt.

HFOV b r y wt p- ttr. T ttr r tt w (b w), w r-t rt t mt rwy prur, tp w pt pump t trqu 3 t 15 Hz (160900 brt/mut). T rt tt rwy pr-ur wt m t (FIGURE 5); t, t t b k r t tw t t pprprt mptutt, tu t t b ytm-ty tu.

Aut ptt r uuy pryz r

py t, p ptubrt w trr rm t t-tr prrm.

T m tt (CO2 r), r r t w mur b : r t t rquy,r t mptu t t, -r t prtry tm, r r bw (w w tr tub uk). Oxyt jutmt r trby mput t m rwy prur t Fio2.

Ventilator settingsin high-requenc oscillator ventilationVttr tt HFOV r46:

Arwy prur mptu (t P rpwr)M rwy prurPrt prtIprtry b wF io2.

Clinical applicationso high-requenc oscillator ventilationT m uuy rr r ARDS p-tt r wm t tt . A rty pub prt46 u-t r HFOV w tr xy-t ur (Fio2 0.7 PEEP 14 mH2O) r tt ur (pH < 7.25 wtt um 6 mL/k prt by wt ptu rwy prur 30 m H2O).

T m trt wtr kw r rw btrut r

trr yprt.

Frequency

Mean airwaypressure

Tidal volume

Airway pressureamplitude (power)

FIGURE 5. High-requency oscillatory ventilation delivers very small mandatory breaths (oscillations)at requencies o up to 900 breaths per minute.

The goal

o HFOV

is to minimize

lung injury,

especially

in ARDS

High-requency oscillatory ventilation


13/14



Theoretical beneftso high-requenc oscillator ventilationCptuy, HFOV pr t -t m rwy prur pr wt t w-

t t um y m. T bftmt mk HFOV t u-prtttt trty.

Evidence o benefto high-requenc oscillator ventilation Physiologic benefts. Am m w t m u m-mt wt HFOV t wt -t-um t tt47,48 w-t-um t tt.49

Patient comort t b tu.

Hwr, urrt ty mpuu wrk brt ptuybrt ptt.50

Outcomes. Sr rtrpt -r rb bttr xyt wt

HFOV ru trpy r r ARDSt wt t m t-t. Tw rmz tr tr tu HFOV -t-um -

t m tt r ry rARDS; HFOV w but m r- trm t.42,5154

High-requenc oscillator ventilation:Bottom lineI try, HFOV pr t bft u-prtt trty, t t r pr-yz r py t ptt. Am tu- upprt t pt. I um ut,HFOV b w t b t pr- bttr xyt but mprmt

t rt mpr wt tm tt. Currty, HFOV bttr rr r ptt wt r ARDSr wm t m t-t .

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ADDRESS: Eduardo Mireles-Cabodevila, MD, Department of Pulmonaryand Critical Care Medicine, University of Arkansas for Medical Sciences,4301 West Markham Street, Slot 555, Little Rock, AR 77205; e mail [email protected].

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