CA2062249A1 - Photoplethysmographics using component-amplitude division multiplexing - Google Patents
Photoplethysmographics using component-amplitude division multiplexingInfo
- Publication number
- CA2062249A1 CA2062249A1 CA002062249A CA2062249A CA2062249A1 CA 2062249 A1 CA2062249 A1 CA 2062249A1 CA 002062249 A CA002062249 A CA 002062249A CA 2062249 A CA2062249 A CA 2062249A CA 2062249 A1 CA2062249 A1 CA 2062249A1
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- Canada
- Prior art keywords
- modulating
- component
- signals
- amplitude
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/41—Detecting, measuring or recording for evaluating the immune or lymphatic systems
- A61B5/414—Evaluating particular organs or parts of the immune or lymphatic systems
- A61B5/417—Evaluating particular organs or parts of the immune or lymphatic systems the bone marrow
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
Abstract
Photoplethysmographics Using Component-Amplitude-Division Multiplexing Abstract A plurality of carrier signals, distinguishable by amplitudes of signal components (e.g., frequency compo-nents), are respectively applied to a plurality of energy emitters (e.g., infrared and red light emitters). A
detector receives the sum of the energy after modulation at each emitter wavelength, e.g. by blood tissue of a patient. An output of the detector is then demultiplexed, whereby a component of modulation at each emitter wave-length may be determined. The carrier signals may com-prise time-varying periodic signals with identical fre-quency and frequency components, such as mixtures of identical sets of pure sine waves. When the number of signal components exceeds the number of emitter wave-lengths, sufficient information is provided during demul-tiplexing to detect and correct errors introduced by ambient light source and other interference.
detector receives the sum of the energy after modulation at each emitter wavelength, e.g. by blood tissue of a patient. An output of the detector is then demultiplexed, whereby a component of modulation at each emitter wave-length may be determined. The carrier signals may com-prise time-varying periodic signals with identical fre-quency and frequency components, such as mixtures of identical sets of pure sine waves. When the number of signal components exceeds the number of emitter wave-lengths, sufficient information is provided during demul-tiplexing to detect and correct errors introduced by ambient light source and other interference.
Description
I~.lA~ 2 l9:33 LYON~ LYO~I P, 3/39 2~2249 ~h~
. a-~b Thi~ invention relatQ~ to ~hotoplethy~mographics.
Mor~ pe~ aally, thi5 lnv~nkion ~lates to a~mponent-ampl1tude-dlvl~lon mult~plex~g and ~omultipl~txlng o~
~ignale for ~n~rared and r~d ab~orp~ion o~ ~loo~
2.
It ~s w~l known in ~he a~t ~o aolleat photo~
ple~hy~ogr~phi~ d~A ~imult~neou~ly a~ a plurall~y of ~n~r~y waveleng~hs. For sxampla, blood ~xygon ~onoen-tration may be mea~u~ed by d~termlning abRorption by a patient'~ t~ues on infrar~d a~d r~ lightr the degree o~ ab~orp~ion i~ ~ypioally di~ren~ fo~ ~h~se two wave-lengthG. In~rare~ and rad llght ~re ~mi~ted in~o the - 15 patient'~ ~issu~6 (e.gO ~ by infr~re~ ~d red LED~) an~ th~
total energy re~e~ve~ to be de~octed ~y ~ slngl~ det~stor (e.g., a photodiod~. Howev~r, one probl~m ls th~t the signal produ~ed b~ th~ ~teo~or mus~ b~ proo~6~ed ~o ~parat2 ~h~ in~rar~d and red portiQn~ ~rom eaoh other.
zo One m~thod o~ th~ p~ior art i~ shown ~n U.~. Pat~n~
No~ 4,407,290. Tlm~-division ~ultlpl~xing i6 used to alterna~ly ~wi~ch on ~he in~r~r~3~ arld ~6~d ~ er~, a~c a ~: r~gu~n~y g~eat~r ~han th~ p~tionk ~ ~ puls~ r~ta . Th~
de~eotor si~nal ls then 6epar~t~d in~o in~rar2d and re~
~ortlon~ by ~ampling in ~yn~hro~y wi~h the on~o~ switch-ing o~ ~he ln~rared ~nd r~d emitters.
While ~hi3~ method ~ucc~ss~ully separates the infrar~d and rqd porti~ns, it ~n~rally r~quire~ that ~amplinq tho d~c~or signal must be ~ynohronize~ with th~ on/of~
30 ~wit¢hing of the in~rared and r~ ~mit~ers. It i~ al~o diffioult w~ a u~ing thl8 me~hod to obmp~nsate ~r n~ise - ;
~ `iP~, 3 92 19:34 LYON& LYOI\I p, ~/39 2~22~9 sources such as am~i~nt lis~h~ and eleatromagn~tia lnter~erenc~.
A ~ond method o~ the pr.~or A~t 1~ s~wn ~n U.~, Pat~nt No. 4,800 r 885. Th~ in~rar~d ~nd re~ em~t~ars are driven at two difPer~n~ ~eguenaie~. Th~ deteQtor sl~nal ~ s ~h~n s~p~rat~d into ln~r~d and ~ed porti~n6 ~y tering a~ ~hosQ ~wo di~f~rPn~ frequen~
While this me~hod suc~ u~Lly 60parate ~he in~rared ~nd red por~on~, the m~tho~ ribe~ in th~ patent lo re~uire~ d~ultiplexing ~ignal6 which ar~ pha~e-synahronized wi~h th~ multiplexing ~r~quencle~, and pro~
ducea a high~r power QU~pUt than ~hs timo-divielon multi-plexing ~et~od. Also, while this method may avoid noi6e soura~s at predetermlned and known ~r~qu~ncies, i~ is di~-ficul~ to oompensat~ ~or noi~ ~ou~c~6 which were notXnown b~f~re thc multiplexlng ~re~uancie~ wer~ 6hos~n.
The invention provld~ a method o~ multipl~xing and de~ultiplexing o~ sig~al~, oall~d ~componen~-amplitude-divi6ion" h~re~n, which m~y be Appll~d to moa~ring blood~i~sue ab~o~p~ion at infrar~d and rod wavalen~th6. A
plurallty of carrier signal~, di~tingui~hable by ~mpli~
tudes oX ~ighal component6 ~e.g., fre~u~ncy compon~nts), are reep~c~iv~ly applied to a plurall~y o~ en~rgy emitter~
(e.g., infra~d and red ~mit~er~ d~tector r~eivQ~
the sum o~ the ~nsrgy a~t~r mo~ulation at ~ach emitter wavel~gth, ~.~. by blood tl6~u~ ~ a pa~ient. An ou~pu~
o~ the d~teator is th~n de~ultiplexad, wh~r~by a ~omponent o~ modulatlon ~t ea~h ~mlt~r w~v~length m~y b2 d~termin~d.
In a pre~erred embodim~nt, ~h~ carrier ~iqnals may oomprise ~im~--varying perio~i~ signal~ with ld~ntlaal frequency an~ frequenay compon~n~ uc:h a~ mixtur0~ o~
id~ntical ~st~ o~ pure sino wav~s. For ex~mpl~, in a 35 pr~errad ~mbodiment, a first ~arrier ~ may compris~ a mixture o~ two sino wave~ al wl + ~ ~Y2, whil~ a oeaond ilA~, 3 ' 92 13:3d LYO~ LYOI~I P, 5/39 2~622~9 car~ier ,B rn~y c:ompri~e a ~i ~e~nt ~nix~ur~ o~ tha same two 5ine w~v~ wl ~ ~2 w~. ~lt~l~na~i~rely, ~ A~ay ~omprlse~
a mixture o~ thre~ sine wave~ ~1 wl i ~2 W2 ~ k3 w3, wh~le ~ may ~o~npri6~ a dif~rent miX'f:Ur~a 0~ ~h~ ~ame khre~ 6ine 5 wa~re ~1 wl + d2 wZ ~ ,/33 W3. When ~he numbe~ of signal compon~nt~ ~xceeda the number o~ ~nitter ~av~lan~th~, su:~-fioient ln~ormatlon is prov~ed during de~nul~iplexing to dete~ and ~orrea~ er~ors introdu~d by aml~ ~ ent 1 ight ~ouro~s ~nd other int~r~rena~.
10 ~ ~
Flgure 1 show~ a blo~k di~ram o~ ~ photopl~hy~mo-~raphlc ~ysl:em aomprising an ~m~odiment c~ ~hs ir,vention.
Flgur~ 2 ~hows a blocX diayram o~ ~h~ compone~t-ampl ~ t-lde-divi~ior; multlpl~x~r ~nd demul~ipleXer of an 15 em~odiment oS the invention.
An em~odl~en~ o~ this invention may b~ usQd together with lnv~ntlons which ara di~olo~ ln a cop~nding appli~
cation titled "P~OTOPLE~Y~MOGRAP~IC~ U~ING ENER~
~0 REDUCING WAVEFO~ 8HAP~NGIl, appli~a~ton Se~Al No. _ _, Lyon ~ ~yon ~ooke~ No~ 1~1/238, riled ~ a~ in th~
nama of ~h~ ~me i~vsnto~, hereby inoorporated by ra~er-~nG~ as 1~ ~ully ~e~ ~orth herein~
Figur~ ~ shows a bloc~ dia~ra~ o~ a photopl~thyemu-graphic 3yRtem ~omprising an ~mbo~lm~n~ o~ ~e l~ven~ion.
A plurallty of energy amltt~r~ 101 may ~ac~ be tuned to a ~pa~a~e wavel~ngth. In a p~er~ed embodiment ~o~
measur~ng blo4d ~xygen, one o~ ~he emit~or ~01 may com-pri-~ an ln~r~rc~ light e~itt~r ~nd may ~perate at a wav~length o~ abou~ 880 nanomet~r~; another one o~ th~
emitters 101 may aompri~e a r~d light emit~er a~d may opsrate at a wavelength of about 655 nan~meter~. ~As uged hs~ein, "light~ r~ers to eleotromagn~tia ~nergy of any IijhF~, 3 ' '~2 13:35 LY01`~ LYOI~ P, 6/~,~
.
~2~
wavel~ngth, ~he~hsr vi~ik71~a o~ nst. 3 ~Iow~er, it may oacur that otha~ wav~l~ng~h6 may be u~3~3rul, suc~ as for measuring blood ca~bon dioxide, blo~d t::arbo~ morlt:xide, other blood ga~ c:onc~3n~ratlons, bloocl gluct: E~a, OI' mor~
gen~rally, o~her chemloal and/or phy~L/::al Conaen~ration~.
In a p~ rred emloo~ t, ea~h o~ the emit~r~ 101 may comprise an LED (such ~ pa~t numbe~ OPC~B03 ma~ by Ma~ktQch In~ernational Corp~ ~r th~ in~r~d LE~ ~n~ part numb~r M~lS00-Pt~ made by ~axXtaah Irlterrl~tional Corp. ~or ~0 the re~ LE~), a~ i6 well known ln ~h~ ~r~, and may ~e collpl~d by m~an~; of an L~D driver 102, a~ 1~ w~ll knowrl in the art, to a carrier output 103 o~ a muxJdelnux circul~
104 ~ee ~igure 2).
En~rgy ~rom tha ~mi~t~r~ lOl i~ appli~d to a ti~ue 5 6~ctlon 105 o~ a patient. In A pxe~rxed em~odiment ~or Ineas~lring blood oxygen, the ti~u~ ~ect;lon 105 i~ prefer-ably cho~en ~uah ~ha~ ener~y ~ m ~la ~ t~r~ lol pa ~:eE;
~hrough the patien~'~ blo~d ve~sel~, ~ueh a~ an ~nd o~ th~
pati~nt'~ ~in~er~ th~a patient's aa~lob~, or ( or neonat~) 20 tha patient~ hand or ~oo~. The t~ua ~e~ion loS may mo~ulate t~e energy ~rom the o~i~te~6 101, as i8 well known ln th~ art , e . g ., by ab~orblng ~o~ o~ ~h~ ~ne~gy at ea~h wavel~ngth. Typically, energy may be modulated by transml 6?~ n 'chrough ~hl3 tl ~3~uo E;Qa~iOn 105, but it m~y ~5 oç-:ur ~hat ~nsrgy may b~ modulaLtad by r~lea~lon or by oth6~r maarl~, A detector lO~ r~a~i~re~ ~n~rgy al~t~r ~nodula~ion by ~he ti~U~ E;ec:~ion lOS and g~ne~ra~ An output signal whioh indicat~ th~ t4~al ene~gy r~o~ived. In a pr~f~rred 30 ~mbodlmen~, the d~tecto~ 106 may ~ompris~ a photo~iode ~uc:h as pa~. number OSI-1140 made~ by Opl:o 50n50~, Inc.), a~ i well knowrl in the art: . An ~ukpu - o~ the det~ct~r 106 is ampli~ll d by arl ampli~ r 107 and ~ouple!d by m~an~
o~ a ~llter 108 to a d~t~ctor i31put 109 o~ the mux/d~mux 35 circui~ 104.
The mux/d~mux cir~uit 104 y~norates a data outx)ul:
~iynal 110 3~ a ~ata ou~put 111~ fo~ each ~nex~sly wav~
MAR, 3'~2 19:~6 L`~OI~I~ LY~N P, 7/3~
2~22~
length, which i.ndloates the ~o~ulation ~hlah th~ tl66u~
s~ction 105 applied ~o that ~nqr~y w~velength. In a pre~err~d embodlment ~or ma~u~1ng blo~ oxy~n, in~orma-~ion ~ch as blood o~yg~n cona~ntr~ion may be calaula~Qd from ~h~ outpu~ ~ig~al, A~ 18 ~ell k~own in th~ art.
exl~
Componen~-ampli~ud~-divl~ion mul~iplexing (''c~DM~
a6 ueed herein, iB def$n~d a~ ~llow~. In CAD~, a plural-lty oP oArri~r elgnale are Qon~tru~to~, aaoh o~ which m~y oompri%e a ~ixtura of aarrier ~ompon~nt~. ~ach carrier signal m~y ~e separately mo~ula~ed, and the ~s~ltants summed. Th~rea ~er, th~ separa~e modulation~ may be recover~d ~rom the sum, a~ die~los~d ~er~in.
~huo, a ~ire~ oarrier may comprise a mixture o~ twa car~ier co~pon~nt~ ~1 wl ~ ~2 w2, while a s~aond carri~r ma~ oomprise a ~i~fer~n~ mixture o~ ~h~ sam~ t~o carri~r componants ~ wl ~ ~2 w2. ~l~er~a~ively, ~ may ~ompr~se a mixture of ~hxoe components ~1 wl + ~2 w~ + ~3 w3, wh~la may comprise a di~çrent mixturs o~ th~ sam~ thr~a ~om ~0 ponents ~1 Wl ~ ~2 w2 ~ ~3 w3.
~ he following r~latlon~ descr~e cons~ruction o~ ea~h carri~r when the num~er o~ aarr~er a~mpon~nt~ ~m) ~nd the number o~ oarrier ~lgnals (n) ~o~h e~ual 2, i.~.
m - n - 2:
2S [ ~1 ~2 ~ [ wl ] [ ~ ] ( ~1 ~2 w~
ar ~ 3) where ~ is a matrix o~ mixing ~actors ~1, a2, ~ 2:
R is a vector o~ ~arrie~ ~omponen~ wl, W2S and ~ i~
a vector o~ ~arrier si~nal~
Applying these relatlon~ to th~ a~e where m = n ~ 2 woul~ b~ cl~ar to one ~f ordinary gkill ln th~ art, a~er 3S peru~l o~ ~h~ speolfication, drawing snd ~lal~8 Aere~n.
Tha ~ollowing relation da~rlb~s ~epara~B modula~lon of ~ac~ ~arrier ~ig~als MAP, 3 92 19: 37 LYO~ L~'GI\I P, 8/39 20622~9 ml ~ * m~ ~ = a ( 114 l wh~re ml i~ a ~ir~t modula~tin~ aff~o~ ~e.y,, at an lnfrared wav~leng~h): ~a i~ a second mod~llatlng effac~ ~.g~, at a re~ wavQleng~h); an~ a is dQ~eated ~um of the modulat~d c:ar~i~r signal6 ~hq dete~d sum a may l; e d~compos~ lnto epar~
part~ ~or ~aoh c:arri~r ~om~onent: wl, w~:
a ~ l wl ~ ~2 wa) ~ ~a ~ wl ~ ~3a wa~ ~15) o~
lo ~ = ~1 wl + t2 w2 ~116) tl - ml al ~ m2 ,Bl ~117 ) ~2 = ml ~2 + m2 ,B2 ~118) or r ~1 a2 r ml ~ r tl 1 ~ t~
- ,~1 ,B2 ~ - m2 t2 or whe~e ~: ~6 the matrlx o~ mlxln~ tor~ 2, ~
,B2 7 ~1 is a vector o~ modula~ion ~f~ak~ ml, m2: and T ~ 8 a vea~or o~ modulated oarrl~r Gomponent par~
Separa~ omponerlts m~y be d~mul~ipl~xed by mul~i plying by tha ~ multipli¢~ e lnver~ o~ tha mixing 2~ matrix It:
( 12 1 ) or 2 2 ) Th~ mixin~ ma~rix ~ 6hould hav~ a lOr~ multiplicativi3 3 D invex~e . It would ~ alear to OIIO o~ ordinary ~kill in th6~ ar~, a~er perusal o~ the epec:i~ioation, drawin~ an~
claim~ h~r~in, that X - I, the id~ntity matrix, ~nd ~ven X ;~ S, woul~ be workable, an~ ar~ withln the ~ope an~
~pi~it o~ the invention. However, a~ u~ed h~rQi~, a 35 mixing matrix X ~ll f~e~e from ~. Al~o, it ie g~n~rally pre~rable that R dif~r~ ~ub~t~ntlally ~rom ~ .
~IIAP, 3'92 19:37 LYON~ L`,~ON P, 9/39 .
~224~
The ~ollowing rolation~ de~aribe ~on~tru~ion of ~ach carri~r wh~n the numbQr of ~a~ri~r ~omponer~ts (m) ~ the nurnb~r o~ carri~r ~ignals (n), whiGh ~ 2 , ~ . ~. m 5 n a 2:
2 ~3 - - Wl ~ - a~
,al ~2 ,~13 W2 ~ (123) lo zl Z2 z3 W~ Z
o~
X f~ 12d.~
where ~ 15 the matrix o~ mixirlg ~aator~ 2, a3, 2, ,~3, zl, z2, z3 ~ the t~ector o~ aarrier compon~nts wl, w2, w3~ an~l ~ is the vector ~ aarrier ~ignal6 ~, ,B, z An add~tlonal row zl, z2, ~3 haE: been ad~d to ~ to præE3erVB it~ inver~a~ility, and an addition~l elemsnt z has b~en added to C: a~ a r~sult . Be~ . u~e no ~arri~r 8ig-~O nal z i8 actually u~, the row zl, z2, 23 may he oho enarbitra~ily, ~o long as X rem~ inv~r~ibl~. O~ 04U~83/
the value ~ç x~l d~pends upon the sel~ot~on o~ the row zl, ~, z~-Bo~ause tlle ~ow zl, 82, z3 may be c~hoean arbitrarlly, 25 X 1 may be cc~mputed more ~h~r~ ono~, u~ g ~nore than on~ row zl, 22, z3~ Thu6, there will b~ Xa) u61n~ z~a, ~2a, Y~, with X'l~ , u~in~ zll~, z2b, æ3~, with ~ 1b, and l~c, uslrlg zlc, z2c:, z3c, wi~h X 1c. a~a, Rb and ~c may ~ach be u6e~1 to ~ompute ~. By ~omparing th~ ~eeultant element~ Qf ~5 3 o gena:rat~d usin~ ~, Rb, and lSo, int~r~r~nc~ in on~ or mor~ oarrl~r components wl, w2, w3 may b~ d~t~cted.
Error~ ~nay b~ ~oxr~cted by ma~ority v~tlng th~ r~sultant el~m~nte Or ~a.
Applyincl ~h~se relat.ion~ to ~h~ c;a~e whe:re m ~ n ~ 2 35 would be cl~ar to c:n~ o~ obdinary ~)cill in ~he a~t, a~t~r perl~al o~ ~h~ epec:l~ication, dr~wings and alaim~ hl3r~in.
lil~R, 3 92 1?:3& LYOII,~ LYON P. 10,'39 2~16~9 ~U~
Figure 2 show~ a blo~c dll~gram o th~ componen~-amplltude-divislon multiplex~r ~n~ ~multipl~X~r o~ an embodim~nt ~f th~ lnvention.
A ~rrier ~o~nponent genera~:c,r aOl gerlerate~ a plural-ity o~ carrier co~nponent~ 20~ wl, w~. ~n a pr~err~d ~mb~diment, par~ o~ eaoh aa~r~x c~ on~n~ 20a wl, w2 ~
allor-~t~d ~o ~aach emitt~ wav~l~n~h. ~lso, in a pre-~erred embodimsnt, ~Ach car~ler co~nponerlk 2 ~a wl, w2 may 10 comprio~ a ~ine wav~, a~ follow~
wl - aof3 ~r Pl t) t343 w2 = 008 121r f2 ~) (20~) wh~re ~1, f2 ar~ fre~uenr~.ie~
In a prefe~red ~mbodim~nt, fl and ~ are chossn such 15 that lnteff2renc~e ~r~m nois~ souro~3s, ~uch a~ ambisnt light and electroma~netla in~er~erenoe, i~ minimiz~d. In a pre:~erred embodiment, fl and ~2 ar~ ~1BO Gho!3~3n ~uah that a bandwidth o~ about 4 Hz ~o~ the modula~in~ e~ t~
ml, m2 is allowed. ~re~auencie~ in th~ ra~g~ o~ ab3ut lo-50 ~z a~a p~eferr~d, but i~ would ~e clear to on~ bl~ ordi-nary 6kill ln t:h~ ar~, a~er pe~u6sl of th~ spe~ifioation, drawing~ an~ im~ he~eln, that o~her Pro~u~noies would ba workable, and ~re wi~hin ~ cope and ~p~ rit o~ th~
invention .
It would also be cl~ar to one o~ o~din~ry sk~ll in the art, af~er p~rusal o~ the s~e;:i~icat~oll, drawing~ and claim~ h~rein, ~ha~ ~here i~ r~o r~quir~e3nt: tha~ wl, w2 mu~t b~ g ine wave~ . Other typ~ rri~r oompone;nt~;
2 02, ~uoh a~ squa~e wa~e~ or o~her wav~orm~, would b~
worlcabl~, and ar~ within th~ soop~ ~nd ~pirit o~ ~ha inv~n~ion.
I~ would al~o be ~laar to orle o~ ordinary æk~ 11 in the art, a~t~r p~aru~al of the ~p~cl~ tlon, drawing~ an~
c}aimæ h~reirl, tha~ th~ invention may be adapt~d ~ m~a-~urem~nt o~ o~h~r conA~ltuent~, ~uah a~ ~lood ~a~bon dioxide, blood caxbon monoxld.~, oth~r blood g~s ~:on~en~ra-MhR, 3 Q2 1~:3g LYGN& L`~GN P, 11i39 2~22~9 g tlvn~;, blood gluao~o, o~ mor~ ~on~3r311y, oth~ ch~mic~al and~or physlaal con~en~ation~.
It wo-lld al80 ba clea~ t~ ona of or~in~ry ~kil l in the art, a~ter perusal oi~ th~ ~peci~ioatlon, drawlng~ and cl~im~ herq~in, ~hat ~he ohoic~ m ~ n ~ 2 i~ particular t~ mea~uxement oP bloo~ oxygen, an~ tha~ other ~ho~oes of m, n would b~ worlcabl~, and ar~3 withl~ the ~cop~3 and ~p~it o the inv~rlt~on . For example, i~ may ocour that other ~hoices o~ m, n may ~e u~3eful, ~uoh a~ ~r meaeuring lo blvod ~ar~on dioxlde 0 blood ~arbon monoxide, othar blood gas ~oncentration~, blood glucose, or mox~ generally, oth2r ~hemlcal Eln~l/or phy~ al concentr~tions.
Ea~h carri~r compon~nt: ~02 wlt w2 i~ ~ouplesl ~y mean~s o~ ~ pha~2 d~lay 205 l:o a ~oefficient ampliier ~06 ~or lS multiplyi~g by a aoeffl~ien~ e~iE the miacing matrix IC, to produc:e ~L mixing produc:~ 207. ~he mlxing produs:ts 207 ar~
~umm~ by a plural i~y o~ mix~ng su~ming ~ix uits ao8 ~o produce a pl~ allty o carrier slgnal~ 20~ his t6 ~he mat~lx m~l~ipli~a~ion ~hown in a~ua~iOn 113, 120 ~ach carrier ~i~nal 20~ a, ~ i3 aoupl~d by means o~
a ~rightne6~ ampli~i2r 210, for ad~ue~ th~ bri~htn~ss o~ a co~reepondin~ bmit~r 101, to th~ corr~ponding o~-~ie~ outpu1: 103 of ~he mux/demux ~ir~ui~ 104.
The det~c:~or i nput lû9 ~ s het~o~yn~d, a~ i5 W6~
25 known in ~he a~$, wi~h the aomplex 6~ier componen~-s 202 wl, w2 ~o r~store eaoh of the mo~ulated ;:arri~r c~mpon~nt6 2g2 wl, w2 to baseband. ~he ~t~ctor input log is ~oupl~d to an iRpUt 0~ eaah of a ~lu~ality o~ h~l:ro~yne el~mant~
211. A seaond lnput o~ eaeh of ~h~ hstrodyn~ el~m~nt~ 211 30 i~ ooupled ~o one of th~ aarri~r compon~n~s 202 wl, w2, ~haæe-ehifte,~ :Eor ~ r~al or ~n imaglnary par~-, a~ i~ ~ell known in the aLrt . The E: haee-E~hlft~d carrier component~
20a w~, w~ are m~lltiplisd to pro~uoo a s~t o~ ~ompï~x ~real and imagin~ry) components 21~ o~ each of th~ a2rriex 35 aom~on~nte Z0~ wl, w2, a~ ie w~ll known in the ar~.
Th~ complax aomponents 21~ are c:o~pled to a ba~eband ~i~t~r al3, which romov~ all oo~npon~rlts exaopt c~m~leae ~1¦A~,3 ' ~2 19~ LYON~ LYOI`I P, 12/39 2~622~9 ba~band aompc~nents ~14. Thf3 co~npl~ax ba~aband c~mpona~t 214 are coupled to a veotor ma~nltud~ computt3r 215, whloh oomput~s a vs~or magnltud~ o~ the complex base~nd Gomponents 21~.
The v~a~or ma~nltu~Q 216 is coupl~d to an inver~e co~fiaient ampli~l~r ~17 i~or mul~iplying l~y aoe~f.i~ient~
of ~he inver~Q mixlng ma~r~ x iC~ o p~oduce an lnYsrse mlxlng p~oduat 2~8~ Th~ invar~e mix~ng produ~t~ 218 ar~
~un~m~d by a plurali~y o~ lm~er~ mixing 6ummin~ cir~uit~
219 to produc~ the data output ~i~nal~ 110 . ~h~ ~ is the mal:rix multlplioa~ion shown in equa~ior~
~he da~a output slgnals 110 e~ah ~n~i~ate the pr~uc:t o~ th~ modulation sff~ct for the cor~pond~ng carrier signal 209 wl, w2~ as multiplied by a corr~ction by 'ch~
corre~ponding brigh~ness amplifier 210. Ea~h da~a o~tpu~
signal llO i~ coupled ~o ~he oor~ ondin~ data output lll of the mux~demux cir~uit 104 .
~n a pr~Qrr~d ~ml~o~imsn~, sign~l gene~tion and 51~
nal manipulatis:~n as d~3 ori3~t~ horein ~r~ pr~f~ral~ly E~er-fo~ed by a digital m~o~pxD~e~or (~uch a~ p~rt number DBPS~iOOl ma~e by MotorDla) s:~pærating under ~o~twara aon-trolO I~ would }~e clear to one o~ ordlnarY ~kill in th~
art, af~r pe~tl6al o~ th~ sp~aiflc~tion, drawings and cl aim~ hersin, ~hat pi~ogxamming a e~anda~ diglt~l mioro -proce~or to p~r~o~m ~ignal ~en~ration and signal manipu-la~ n as de60rib~d h~arein woul~ be a ~t~aightforwaxd ~a6k and woul~ not require undu~ experim~ntat~ on.
It would ~e ol~ar t~ on~ o~ o~dinary 3kill in the art, a~ter perusal of the ~peoirlcalti~n, drawing~ and ~o clalms h~ar~in, that the inv~n~Glon may bq ~ombln~d wi~h known methodE~ o~ aompu~ing bloo~ oxy61erl Gonaentr~tion Ind other blood g~ values from thQ data output signal~ 110 whlch are produ~ed. Providing a ~ys~em which comblne~ ~he inventlon wit:h such known m~hode would b~ ~ ~traight~or-~5 ward task, a~ter p~ru~al of the ~p~cifiaation, drawing~
and clalms n~rein, and woul~ no~ r~quire undu~
experim~ntatiotl .
MAP, 3 '`~2 19:i:) Li'OI``I& LYON P, 13/39 2~62249 ~l~s~na~i~ Em~?QU imen"l;~
Whlle prc!~err~3tl embo~ aent~ are ~l~clo~d hersain, many v~riiatians ~re po~ whlc~h remain wlthin th~
czonoept and 5COpla o~E ~he lnven~,lorl, and the~ Y~riatlon~
5 would become cl~ar l:o on~ u~ or~ nary ekill in 'ch~ ~rt aft~r peru3~l of ~he ~peoi~i~æ~ion, drawing~ and ol~lms herein .
. a-~b Thi~ invention relatQ~ to ~hotoplethy~mographics.
Mor~ pe~ aally, thi5 lnv~nkion ~lates to a~mponent-ampl1tude-dlvl~lon mult~plex~g and ~omultipl~txlng o~
~ignale for ~n~rared and r~d ab~orp~ion o~ ~loo~
2.
It ~s w~l known in ~he a~t ~o aolleat photo~
ple~hy~ogr~phi~ d~A ~imult~neou~ly a~ a plurall~y of ~n~r~y waveleng~hs. For sxampla, blood ~xygon ~onoen-tration may be mea~u~ed by d~termlning abRorption by a patient'~ t~ues on infrar~d a~d r~ lightr the degree o~ ab~orp~ion i~ ~ypioally di~ren~ fo~ ~h~se two wave-lengthG. In~rare~ and rad llght ~re ~mi~ted in~o the - 15 patient'~ ~issu~6 (e.gO ~ by infr~re~ ~d red LED~) an~ th~
total energy re~e~ve~ to be de~octed ~y ~ slngl~ det~stor (e.g., a photodiod~. Howev~r, one probl~m ls th~t the signal produ~ed b~ th~ ~teo~or mus~ b~ proo~6~ed ~o ~parat2 ~h~ in~rar~d and red portiQn~ ~rom eaoh other.
zo One m~thod o~ th~ p~ior art i~ shown ~n U.~. Pat~n~
No~ 4,407,290. Tlm~-division ~ultlpl~xing i6 used to alterna~ly ~wi~ch on ~he in~r~r~3~ arld ~6~d ~ er~, a~c a ~: r~gu~n~y g~eat~r ~han th~ p~tionk ~ ~ puls~ r~ta . Th~
de~eotor si~nal ls then 6epar~t~d in~o in~rar2d and re~
~ortlon~ by ~ampling in ~yn~hro~y wi~h the on~o~ switch-ing o~ ~he ln~rared ~nd r~d emitters.
While ~hi3~ method ~ucc~ss~ully separates the infrar~d and rqd porti~ns, it ~n~rally r~quire~ that ~amplinq tho d~c~or signal must be ~ynohronize~ with th~ on/of~
30 ~wit¢hing of the in~rared and r~ ~mit~ers. It i~ al~o diffioult w~ a u~ing thl8 me~hod to obmp~nsate ~r n~ise - ;
~ `iP~, 3 92 19:34 LYON& LYOI\I p, ~/39 2~22~9 sources such as am~i~nt lis~h~ and eleatromagn~tia lnter~erenc~.
A ~ond method o~ the pr.~or A~t 1~ s~wn ~n U.~, Pat~nt No. 4,800 r 885. Th~ in~rar~d ~nd re~ em~t~ars are driven at two difPer~n~ ~eguenaie~. Th~ deteQtor sl~nal ~ s ~h~n s~p~rat~d into ln~r~d and ~ed porti~n6 ~y tering a~ ~hosQ ~wo di~f~rPn~ frequen~
While this me~hod suc~ u~Lly 60parate ~he in~rared ~nd red por~on~, the m~tho~ ribe~ in th~ patent lo re~uire~ d~ultiplexing ~ignal6 which ar~ pha~e-synahronized wi~h th~ multiplexing ~r~quencle~, and pro~
ducea a high~r power QU~pUt than ~hs timo-divielon multi-plexing ~et~od. Also, while this method may avoid noi6e soura~s at predetermlned and known ~r~qu~ncies, i~ is di~-ficul~ to oompensat~ ~or noi~ ~ou~c~6 which were notXnown b~f~re thc multiplexlng ~re~uancie~ wer~ 6hos~n.
The invention provld~ a method o~ multipl~xing and de~ultiplexing o~ sig~al~, oall~d ~componen~-amplitude-divi6ion" h~re~n, which m~y be Appll~d to moa~ring blood~i~sue ab~o~p~ion at infrar~d and rod wavalen~th6. A
plurallty of carrier signal~, di~tingui~hable by ~mpli~
tudes oX ~ighal component6 ~e.g., fre~u~ncy compon~nts), are reep~c~iv~ly applied to a plurall~y o~ en~rgy emitter~
(e.g., infra~d and red ~mit~er~ d~tector r~eivQ~
the sum o~ the ~nsrgy a~t~r mo~ulation at ~ach emitter wavel~gth, ~.~. by blood tl6~u~ ~ a pa~ient. An ou~pu~
o~ the d~teator is th~n de~ultiplexad, wh~r~by a ~omponent o~ modulatlon ~t ea~h ~mlt~r w~v~length m~y b2 d~termin~d.
In a pre~erred embodim~nt, ~h~ carrier ~iqnals may oomprise ~im~--varying perio~i~ signal~ with ld~ntlaal frequency an~ frequenay compon~n~ uc:h a~ mixtur0~ o~
id~ntical ~st~ o~ pure sino wav~s. For ex~mpl~, in a 35 pr~errad ~mbodiment, a first ~arrier ~ may compris~ a mixture o~ two sino wave~ al wl + ~ ~Y2, whil~ a oeaond ilA~, 3 ' 92 13:3d LYO~ LYOI~I P, 5/39 2~622~9 car~ier ,B rn~y c:ompri~e a ~i ~e~nt ~nix~ur~ o~ tha same two 5ine w~v~ wl ~ ~2 w~. ~lt~l~na~i~rely, ~ A~ay ~omprlse~
a mixture o~ thre~ sine wave~ ~1 wl i ~2 W2 ~ k3 w3, wh~le ~ may ~o~npri6~ a dif~rent miX'f:Ur~a 0~ ~h~ ~ame khre~ 6ine 5 wa~re ~1 wl + d2 wZ ~ ,/33 W3. When ~he numbe~ of signal compon~nt~ ~xceeda the number o~ ~nitter ~av~lan~th~, su:~-fioient ln~ormatlon is prov~ed during de~nul~iplexing to dete~ and ~orrea~ er~ors introdu~d by aml~ ~ ent 1 ight ~ouro~s ~nd other int~r~rena~.
10 ~ ~
Flgure 1 show~ a blo~k di~ram o~ ~ photopl~hy~mo-~raphlc ~ysl:em aomprising an ~m~odiment c~ ~hs ir,vention.
Flgur~ 2 ~hows a blocX diayram o~ ~h~ compone~t-ampl ~ t-lde-divi~ior; multlpl~x~r ~nd demul~ipleXer of an 15 em~odiment oS the invention.
An em~odl~en~ o~ this invention may b~ usQd together with lnv~ntlons which ara di~olo~ ln a cop~nding appli~
cation titled "P~OTOPLE~Y~MOGRAP~IC~ U~ING ENER~
~0 REDUCING WAVEFO~ 8HAP~NGIl, appli~a~ton Se~Al No. _ _, Lyon ~ ~yon ~ooke~ No~ 1~1/238, riled ~ a~ in th~
nama of ~h~ ~me i~vsnto~, hereby inoorporated by ra~er-~nG~ as 1~ ~ully ~e~ ~orth herein~
Figur~ ~ shows a bloc~ dia~ra~ o~ a photopl~thyemu-graphic 3yRtem ~omprising an ~mbo~lm~n~ o~ ~e l~ven~ion.
A plurallty of energy amltt~r~ 101 may ~ac~ be tuned to a ~pa~a~e wavel~ngth. In a p~er~ed embodiment ~o~
measur~ng blo4d ~xygen, one o~ ~he emit~or ~01 may com-pri-~ an ln~r~rc~ light e~itt~r ~nd may ~perate at a wav~length o~ abou~ 880 nanomet~r~; another one o~ th~
emitters 101 may aompri~e a r~d light emit~er a~d may opsrate at a wavelength of about 655 nan~meter~. ~As uged hs~ein, "light~ r~ers to eleotromagn~tia ~nergy of any IijhF~, 3 ' '~2 13:35 LY01`~ LYOI~ P, 6/~,~
.
~2~
wavel~ngth, ~he~hsr vi~ik71~a o~ nst. 3 ~Iow~er, it may oacur that otha~ wav~l~ng~h6 may be u~3~3rul, suc~ as for measuring blood ca~bon dioxide, blo~d t::arbo~ morlt:xide, other blood ga~ c:onc~3n~ratlons, bloocl gluct: E~a, OI' mor~
gen~rally, o~her chemloal and/or phy~L/::al Conaen~ration~.
In a p~ rred emloo~ t, ea~h o~ the emit~r~ 101 may comprise an LED (such ~ pa~t numbe~ OPC~B03 ma~ by Ma~ktQch In~ernational Corp~ ~r th~ in~r~d LE~ ~n~ part numb~r M~lS00-Pt~ made by ~axXtaah Irlterrl~tional Corp. ~or ~0 the re~ LE~), a~ i6 well known ln ~h~ ~r~, and may ~e collpl~d by m~an~; of an L~D driver 102, a~ 1~ w~ll knowrl in the art, to a carrier output 103 o~ a muxJdelnux circul~
104 ~ee ~igure 2).
En~rgy ~rom tha ~mi~t~r~ lOl i~ appli~d to a ti~ue 5 6~ctlon 105 o~ a patient. In A pxe~rxed em~odiment ~or Ineas~lring blood oxygen, the ti~u~ ~ect;lon 105 i~ prefer-ably cho~en ~uah ~ha~ ener~y ~ m ~la ~ t~r~ lol pa ~:eE;
~hrough the patien~'~ blo~d ve~sel~, ~ueh a~ an ~nd o~ th~
pati~nt'~ ~in~er~ th~a patient's aa~lob~, or ( or neonat~) 20 tha patient~ hand or ~oo~. The t~ua ~e~ion loS may mo~ulate t~e energy ~rom the o~i~te~6 101, as i8 well known ln th~ art , e . g ., by ab~orblng ~o~ o~ ~h~ ~ne~gy at ea~h wavel~ngth. Typically, energy may be modulated by transml 6?~ n 'chrough ~hl3 tl ~3~uo E;Qa~iOn 105, but it m~y ~5 oç-:ur ~hat ~nsrgy may b~ modulaLtad by r~lea~lon or by oth6~r maarl~, A detector lO~ r~a~i~re~ ~n~rgy al~t~r ~nodula~ion by ~he ti~U~ E;ec:~ion lOS and g~ne~ra~ An output signal whioh indicat~ th~ t4~al ene~gy r~o~ived. In a pr~f~rred 30 ~mbodlmen~, the d~tecto~ 106 may ~ompris~ a photo~iode ~uc:h as pa~. number OSI-1140 made~ by Opl:o 50n50~, Inc.), a~ i well knowrl in the art: . An ~ukpu - o~ the det~ct~r 106 is ampli~ll d by arl ampli~ r 107 and ~ouple!d by m~an~
o~ a ~llter 108 to a d~t~ctor i31put 109 o~ the mux/d~mux 35 circui~ 104.
The mux/d~mux cir~uit 104 y~norates a data outx)ul:
~iynal 110 3~ a ~ata ou~put 111~ fo~ each ~nex~sly wav~
MAR, 3'~2 19:~6 L`~OI~I~ LY~N P, 7/3~
2~22~
length, which i.ndloates the ~o~ulation ~hlah th~ tl66u~
s~ction 105 applied ~o that ~nqr~y w~velength. In a pre~err~d embodlment ~or ma~u~1ng blo~ oxy~n, in~orma-~ion ~ch as blood o~yg~n cona~ntr~ion may be calaula~Qd from ~h~ outpu~ ~ig~al, A~ 18 ~ell k~own in th~ art.
exl~
Componen~-ampli~ud~-divl~ion mul~iplexing (''c~DM~
a6 ueed herein, iB def$n~d a~ ~llow~. In CAD~, a plural-lty oP oArri~r elgnale are Qon~tru~to~, aaoh o~ which m~y oompri%e a ~ixtura of aarrier ~ompon~nt~. ~ach carrier signal m~y ~e separately mo~ula~ed, and the ~s~ltants summed. Th~rea ~er, th~ separa~e modulation~ may be recover~d ~rom the sum, a~ die~los~d ~er~in.
~huo, a ~ire~ oarrier may comprise a mixture o~ twa car~ier co~pon~nt~ ~1 wl ~ ~2 w2, while a s~aond carri~r ma~ oomprise a ~i~fer~n~ mixture o~ ~h~ sam~ t~o carri~r componants ~ wl ~ ~2 w2. ~l~er~a~ively, ~ may ~ompr~se a mixture of ~hxoe components ~1 wl + ~2 w~ + ~3 w3, wh~la may comprise a di~çrent mixturs o~ th~ sam~ thr~a ~om ~0 ponents ~1 Wl ~ ~2 w2 ~ ~3 w3.
~ he following r~latlon~ descr~e cons~ruction o~ ea~h carri~r when the num~er o~ aarr~er a~mpon~nt~ ~m) ~nd the number o~ oarrier ~lgnals (n) ~o~h e~ual 2, i.~.
m - n - 2:
2S [ ~1 ~2 ~ [ wl ] [ ~ ] ( ~1 ~2 w~
ar ~ 3) where ~ is a matrix o~ mixing ~actors ~1, a2, ~ 2:
R is a vector o~ ~arrie~ ~omponen~ wl, W2S and ~ i~
a vector o~ ~arrier si~nal~
Applying these relatlon~ to th~ a~e where m = n ~ 2 woul~ b~ cl~ar to one ~f ordinary gkill ln th~ art, a~er 3S peru~l o~ ~h~ speolfication, drawing snd ~lal~8 Aere~n.
Tha ~ollowing relation da~rlb~s ~epara~B modula~lon of ~ac~ ~arrier ~ig~als MAP, 3 92 19: 37 LYO~ L~'GI\I P, 8/39 20622~9 ml ~ * m~ ~ = a ( 114 l wh~re ml i~ a ~ir~t modula~tin~ aff~o~ ~e.y,, at an lnfrared wav~leng~h): ~a i~ a second mod~llatlng effac~ ~.g~, at a re~ wavQleng~h); an~ a is dQ~eated ~um of the modulat~d c:ar~i~r signal6 ~hq dete~d sum a may l; e d~compos~ lnto epar~
part~ ~or ~aoh c:arri~r ~om~onent: wl, w~:
a ~ l wl ~ ~2 wa) ~ ~a ~ wl ~ ~3a wa~ ~15) o~
lo ~ = ~1 wl + t2 w2 ~116) tl - ml al ~ m2 ,Bl ~117 ) ~2 = ml ~2 + m2 ,B2 ~118) or r ~1 a2 r ml ~ r tl 1 ~ t~
- ,~1 ,B2 ~ - m2 t2 or whe~e ~: ~6 the matrlx o~ mlxln~ tor~ 2, ~
,B2 7 ~1 is a vector o~ modula~ion ~f~ak~ ml, m2: and T ~ 8 a vea~or o~ modulated oarrl~r Gomponent par~
Separa~ omponerlts m~y be d~mul~ipl~xed by mul~i plying by tha ~ multipli¢~ e lnver~ o~ tha mixing 2~ matrix It:
( 12 1 ) or 2 2 ) Th~ mixin~ ma~rix ~ 6hould hav~ a lOr~ multiplicativi3 3 D invex~e . It would ~ alear to OIIO o~ ordinary ~kill in th6~ ar~, a~er perusal o~ the epec:i~ioation, drawin~ an~
claim~ h~r~in, that X - I, the id~ntity matrix, ~nd ~ven X ;~ S, woul~ be workable, an~ ar~ withln the ~ope an~
~pi~it o~ the invention. However, a~ u~ed h~rQi~, a 35 mixing matrix X ~ll f~e~e from ~. Al~o, it ie g~n~rally pre~rable that R dif~r~ ~ub~t~ntlally ~rom ~ .
~IIAP, 3'92 19:37 LYON~ L`,~ON P, 9/39 .
~224~
The ~ollowing rolation~ de~aribe ~on~tru~ion of ~ach carri~r wh~n the numbQr of ~a~ri~r ~omponer~ts (m) ~ the nurnb~r o~ carri~r ~ignals (n), whiGh ~ 2 , ~ . ~. m 5 n a 2:
2 ~3 - - Wl ~ - a~
,al ~2 ,~13 W2 ~ (123) lo zl Z2 z3 W~ Z
o~
X f~ 12d.~
where ~ 15 the matrix o~ mixirlg ~aator~ 2, a3, 2, ,~3, zl, z2, z3 ~ the t~ector o~ aarrier compon~nts wl, w2, w3~ an~l ~ is the vector ~ aarrier ~ignal6 ~, ,B, z An add~tlonal row zl, z2, ~3 haE: been ad~d to ~ to præE3erVB it~ inver~a~ility, and an addition~l elemsnt z has b~en added to C: a~ a r~sult . Be~ . u~e no ~arri~r 8ig-~O nal z i8 actually u~, the row zl, z2, 23 may he oho enarbitra~ily, ~o long as X rem~ inv~r~ibl~. O~ 04U~83/
the value ~ç x~l d~pends upon the sel~ot~on o~ the row zl, ~, z~-Bo~ause tlle ~ow zl, 82, z3 may be c~hoean arbitrarlly, 25 X 1 may be cc~mputed more ~h~r~ ono~, u~ g ~nore than on~ row zl, 22, z3~ Thu6, there will b~ Xa) u61n~ z~a, ~2a, Y~, with X'l~ , u~in~ zll~, z2b, æ3~, with ~ 1b, and l~c, uslrlg zlc, z2c:, z3c, wi~h X 1c. a~a, Rb and ~c may ~ach be u6e~1 to ~ompute ~. By ~omparing th~ ~eeultant element~ Qf ~5 3 o gena:rat~d usin~ ~, Rb, and lSo, int~r~r~nc~ in on~ or mor~ oarrl~r components wl, w2, w3 may b~ d~t~cted.
Error~ ~nay b~ ~oxr~cted by ma~ority v~tlng th~ r~sultant el~m~nte Or ~a.
Applyincl ~h~se relat.ion~ to ~h~ c;a~e whe:re m ~ n ~ 2 35 would be cl~ar to c:n~ o~ obdinary ~)cill in ~he a~t, a~t~r perl~al o~ ~h~ epec:l~ication, dr~wings and alaim~ hl3r~in.
lil~R, 3 92 1?:3& LYOII,~ LYON P. 10,'39 2~16~9 ~U~
Figure 2 show~ a blo~c dll~gram o th~ componen~-amplltude-divislon multiplex~r ~n~ ~multipl~X~r o~ an embodim~nt ~f th~ lnvention.
A ~rrier ~o~nponent genera~:c,r aOl gerlerate~ a plural-ity o~ carrier co~nponent~ 20~ wl, w~. ~n a pr~err~d ~mb~diment, par~ o~ eaoh aa~r~x c~ on~n~ 20a wl, w2 ~
allor-~t~d ~o ~aach emitt~ wav~l~n~h. ~lso, in a pre-~erred embodimsnt, ~Ach car~ler co~nponerlk 2 ~a wl, w2 may 10 comprio~ a ~ine wav~, a~ follow~
wl - aof3 ~r Pl t) t343 w2 = 008 121r f2 ~) (20~) wh~re ~1, f2 ar~ fre~uenr~.ie~
In a prefe~red ~mbodim~nt, fl and ~ are chossn such 15 that lnteff2renc~e ~r~m nois~ souro~3s, ~uch a~ ambisnt light and electroma~netla in~er~erenoe, i~ minimiz~d. In a pre:~erred embodiment, fl and ~2 ar~ ~1BO Gho!3~3n ~uah that a bandwidth o~ about 4 Hz ~o~ the modula~in~ e~ t~
ml, m2 is allowed. ~re~auencie~ in th~ ra~g~ o~ ab3ut lo-50 ~z a~a p~eferr~d, but i~ would ~e clear to on~ bl~ ordi-nary 6kill ln t:h~ ar~, a~er pe~u6sl of th~ spe~ifioation, drawing~ an~ im~ he~eln, that o~her Pro~u~noies would ba workable, and ~re wi~hin ~ cope and ~p~ rit o~ th~
invention .
It would also be cl~ar to one o~ o~din~ry sk~ll in the art, af~er p~rusal o~ the s~e;:i~icat~oll, drawing~ and claim~ h~rein, ~ha~ ~here i~ r~o r~quir~e3nt: tha~ wl, w2 mu~t b~ g ine wave~ . Other typ~ rri~r oompone;nt~;
2 02, ~uoh a~ squa~e wa~e~ or o~her wav~orm~, would b~
worlcabl~, and ar~ within th~ soop~ ~nd ~pirit o~ ~ha inv~n~ion.
I~ would al~o be ~laar to orle o~ ordinary æk~ 11 in the art, a~t~r p~aru~al of the ~p~cl~ tlon, drawing~ an~
c}aimæ h~reirl, tha~ th~ invention may be adapt~d ~ m~a-~urem~nt o~ o~h~r conA~ltuent~, ~uah a~ ~lood ~a~bon dioxide, blood caxbon monoxld.~, oth~r blood g~s ~:on~en~ra-MhR, 3 Q2 1~:3g LYGN& L`~GN P, 11i39 2~22~9 g tlvn~;, blood gluao~o, o~ mor~ ~on~3r311y, oth~ ch~mic~al and~or physlaal con~en~ation~.
It wo-lld al80 ba clea~ t~ ona of or~in~ry ~kil l in the art, a~ter perusal oi~ th~ ~peci~ioatlon, drawlng~ and cl~im~ herq~in, ~hat ~he ohoic~ m ~ n ~ 2 i~ particular t~ mea~uxement oP bloo~ oxygen, an~ tha~ other ~ho~oes of m, n would b~ worlcabl~, and ar~3 withl~ the ~cop~3 and ~p~it o the inv~rlt~on . For example, i~ may ocour that other ~hoices o~ m, n may ~e u~3eful, ~uoh a~ ~r meaeuring lo blvod ~ar~on dioxlde 0 blood ~arbon monoxide, othar blood gas ~oncentration~, blood glucose, or mox~ generally, oth2r ~hemlcal Eln~l/or phy~ al concentr~tions.
Ea~h carri~r compon~nt: ~02 wlt w2 i~ ~ouplesl ~y mean~s o~ ~ pha~2 d~lay 205 l:o a ~oefficient ampliier ~06 ~or lS multiplyi~g by a aoeffl~ien~ e~iE the miacing matrix IC, to produc:e ~L mixing produc:~ 207. ~he mlxing produs:ts 207 ar~
~umm~ by a plural i~y o~ mix~ng su~ming ~ix uits ao8 ~o produce a pl~ allty o carrier slgnal~ 20~ his t6 ~he mat~lx m~l~ipli~a~ion ~hown in a~ua~iOn 113, 120 ~ach carrier ~i~nal 20~ a, ~ i3 aoupl~d by means o~
a ~rightne6~ ampli~i2r 210, for ad~ue~ th~ bri~htn~ss o~ a co~reepondin~ bmit~r 101, to th~ corr~ponding o~-~ie~ outpu1: 103 of ~he mux/demux ~ir~ui~ 104.
The det~c:~or i nput lû9 ~ s het~o~yn~d, a~ i5 W6~
25 known in ~he a~$, wi~h the aomplex 6~ier componen~-s 202 wl, w2 ~o r~store eaoh of the mo~ulated ;:arri~r c~mpon~nt6 2g2 wl, w2 to baseband. ~he ~t~ctor input log is ~oupl~d to an iRpUt 0~ eaah of a ~lu~ality o~ h~l:ro~yne el~mant~
211. A seaond lnput o~ eaeh of ~h~ hstrodyn~ el~m~nt~ 211 30 i~ ooupled ~o one of th~ aarri~r compon~n~s 202 wl, w2, ~haæe-ehifte,~ :Eor ~ r~al or ~n imaglnary par~-, a~ i~ ~ell known in the aLrt . The E: haee-E~hlft~d carrier component~
20a w~, w~ are m~lltiplisd to pro~uoo a s~t o~ ~ompï~x ~real and imagin~ry) components 21~ o~ each of th~ a2rriex 35 aom~on~nte Z0~ wl, w2, a~ ie w~ll known in the ar~.
Th~ complax aomponents 21~ are c:o~pled to a ba~eband ~i~t~r al3, which romov~ all oo~npon~rlts exaopt c~m~leae ~1¦A~,3 ' ~2 19~ LYON~ LYOI`I P, 12/39 2~622~9 ba~band aompc~nents ~14. Thf3 co~npl~ax ba~aband c~mpona~t 214 are coupled to a veotor ma~nltud~ computt3r 215, whloh oomput~s a vs~or magnltud~ o~ the complex base~nd Gomponents 21~.
The v~a~or ma~nltu~Q 216 is coupl~d to an inver~e co~fiaient ampli~l~r ~17 i~or mul~iplying l~y aoe~f.i~ient~
of ~he inver~Q mixlng ma~r~ x iC~ o p~oduce an lnYsrse mlxlng p~oduat 2~8~ Th~ invar~e mix~ng produ~t~ 218 ar~
~un~m~d by a plurali~y o~ lm~er~ mixing 6ummin~ cir~uit~
219 to produc~ the data output ~i~nal~ 110 . ~h~ ~ is the mal:rix multlplioa~ion shown in equa~ior~
~he da~a output slgnals 110 e~ah ~n~i~ate the pr~uc:t o~ th~ modulation sff~ct for the cor~pond~ng carrier signal 209 wl, w2~ as multiplied by a corr~ction by 'ch~
corre~ponding brigh~ness amplifier 210. Ea~h da~a o~tpu~
signal llO i~ coupled ~o ~he oor~ ondin~ data output lll of the mux~demux cir~uit 104 .
~n a pr~Qrr~d ~ml~o~imsn~, sign~l gene~tion and 51~
nal manipulatis:~n as d~3 ori3~t~ horein ~r~ pr~f~ral~ly E~er-fo~ed by a digital m~o~pxD~e~or (~uch a~ p~rt number DBPS~iOOl ma~e by MotorDla) s:~pærating under ~o~twara aon-trolO I~ would }~e clear to one o~ ordlnarY ~kill in th~
art, af~r pe~tl6al o~ th~ sp~aiflc~tion, drawings and cl aim~ hersin, ~hat pi~ogxamming a e~anda~ diglt~l mioro -proce~or to p~r~o~m ~ignal ~en~ration and signal manipu-la~ n as de60rib~d h~arein woul~ be a ~t~aightforwaxd ~a6k and woul~ not require undu~ experim~ntat~ on.
It would ~e ol~ar t~ on~ o~ o~dinary 3kill in the art, a~ter perusal of the ~peoirlcalti~n, drawing~ and ~o clalms h~ar~in, that the inv~n~Glon may bq ~ombln~d wi~h known methodE~ o~ aompu~ing bloo~ oxy61erl Gonaentr~tion Ind other blood g~ values from thQ data output signal~ 110 whlch are produ~ed. Providing a ~ys~em which comblne~ ~he inventlon wit:h such known m~hode would b~ ~ ~traight~or-~5 ward task, a~ter p~ru~al of the ~p~cifiaation, drawing~
and clalms n~rein, and woul~ no~ r~quire undu~
experim~ntatiotl .
MAP, 3 '`~2 19:i:) Li'OI``I& LYON P, 13/39 2~62249 ~l~s~na~i~ Em~?QU imen"l;~
Whlle prc!~err~3tl embo~ aent~ are ~l~clo~d hersain, many v~riiatians ~re po~ whlc~h remain wlthin th~
czonoept and 5COpla o~E ~he lnven~,lorl, and the~ Y~riatlon~
5 would become cl~ar l:o on~ u~ or~ nary ekill in 'ch~ ~rt aft~r peru3~l of ~he ~peoi~i~æ~ion, drawing~ and ol~lms herein .
Claims (62)
1. A device for collecting photoplethysmographic data, comprising means for generating a first and a second sig-nal, each comprising a set of component signals, said first and second signals being distinguishable by ampli-tudes of said component signals;
means for applying said first and second signals to a modulating medium;
means for detecting a composite signal at an output of said modulating medium, said modulating medium having a first an a second modulating effect; and means for generating a first and a second output signal responsive to said composite signal, said first output signal indicating said first modulating effect and said second output signal indicating said second modulat-ing effect.
means for applying said first and second signals to a modulating medium;
means for detecting a composite signal at an output of said modulating medium, said modulating medium having a first an a second modulating effect; and means for generating a first and a second output signal responsive to said composite signal, said first output signal indicating said first modulating effect and said second output signal indicating said second modulat-ing effect.
2. A device as in claim 1, wherein said first and second signals are periodic time-varying signals with identical periods.
3. A device as in claim 1, wherein said first and second signals have identical frequency components.
4. A device as in claim 1, wherein said means for detecting comprises a photodiode.
5. A device as in claim 1, wherein said composite signal comprises a sum of said
6. A device for collecting photoplethysmographic data, comprising means for generating a plurality of carrier signals, each comprising a set of component signals, said carrier signals being distinguishable by amplitudes of said component signals;
means for applying at least two of said carrier signals to a modulating medium;
means for detecting a composite signal at an output of said modulating medium, said modulating medium having a plurality of modulating effect; and means for generating a plurality of output signals responsive to said composite signal, each said output signal indicating one said modulating effect,
means for applying at least two of said carrier signals to a modulating medium;
means for detecting a composite signal at an output of said modulating medium, said modulating medium having a plurality of modulating effect; and means for generating a plurality of output signals responsive to said composite signal, each said output signal indicating one said modulating effect,
7. A device for collecting photoplethysmographic data, comprising means for multiplying a mixing matrix and a vector of component signals;
means for applying a plurality of modulating effects to a resultant of said means for multiplying; and means for multiplying an inverse of said mixing matrix and a resultant of said means for applying.
means for applying a plurality of modulating effects to a resultant of said means for multiplying; and means for multiplying an inverse of said mixing matrix and a resultant of said means for applying.
8. A device as in claim 1 or 7, wherein said photo-plethysmographic data comprises blood gas data.
9. A device as in claim 1 or 7, wherein said photo-plethysmographic data comprises at least one of the group:
blood oxygen, blood carbon dioxide, blood carbon monoxide.
blood oxygen, blood carbon dioxide, blood carbon monoxide.
10. A device as in claim 7, wherein said mixing matrix is a square matrix.
11. A device as in claim 1 or 7, wherein at least one of said component signals comprises a sum of at least one of the group: a sine wave, a square wave.
12. A device as in claim 1 or 7, wherein said means for applying comprises a plurality of light-emitters.
13. A device as in claim 1 or 7, wherein said means for applying comprises a plurality of light-emitters tuned to a plurality of wavelengths.
14. A device as in claim 7, wherein said means for applying comprises a modulating medium.
15. A device as in claim 1 or 14, wherein said modu-lating medium comprises animal tissue.
16. A device as in claim 1 or 14, wherein said modu-lating medium comprises at least one of the group: blood, blood vessels, bone marrow, ligament, muscle, skin.
17. A device as in claim 1 or 7, wherein at least one of said modulating effects comprises amplitude modulation.
18. A device as in claim 1 or 7, wherein said modu-lating effects comprise an amplitude modulation effect which varies with energy wavelength.
19. A device as in claim 1 or 7, wherein at least one of said modulating effects comprises a time-varying component.
20. A device as in claim 1 or 7, wherein at least one of said modulating effect comprises a time-varying component which is correlated with a biological process,
21. A device as in claim 1 or 7, wherein at least one of said modulating effects comprises at least one transmission response of a modulating medium.
22. A device as in claim 7, comprising means for detecting a composite resultant of said means for applying; and means for separating said composite resultant into a vector resultant.
23. A device as in claim 22, wherein said means for separating comprises at least one hetrodyning element.
24. A device as in claim 22, wherein said composite resultant comprises a sum of at least two elements of said vector resultant.
25. A device for collecting photplethysmographic data, comprising means for component-amplitude-division multi-plexing a plurality of modulating signals; and means for component-amplitude-division demulti-plexing said plurality of signals.
26. A device as in claim 25, wherein said plurality of modulating signals comprises an infrared wavelength modulating signal and a red wavelength modulating signal.
27. A device as in claim 25, wherein said means for component-amplitude-division multiplexing and said means for component-amplitude-division demultiplexing collec-tively comprise a plurality of carrier signals.
28. A device as in claim 25, wherein said means for component-amplitude-division multiplexing and said means for component-amplitude-division demultiplexing collec-tively comprise a plurality of carrier components.
29. A device as in claim 25, wherein said means for component-amplitude-division multiplexing and said means for component-amplitude-division demultiplexing collec-tively comprise a mixing matrix and an inverse of said mixing matrix.
30. A device as in claim 25, wherein said means for component-amplitude-division multiplexing and said means for component-amplitude-division demultiplexing collec-tively comprise means for error detection.
31. A device as in claim 30, wherein said means for error detection comprises a number of carrier components in excess of a number of carrier signals.
32. A device as in claim 30, wherein said means for error detection comprises a plurality of mixing matrices.
33. A device as in claim 25, wherein said means for component-amplitude-division multiplexing and said means for components-amplitude-division demultiplexing collec-tively comprise means for error correction.
34. A device as in claim 33, wherein said means for error correction comprises means for majority voting a resultant of component-amplitude-division multiplexing and demultiplexing with a plurality of mixing matrices.
35. A device for collecting photoplethysmographic data, comprising a plurality of n emitters disposed to emit energy into a modulating medium at a plurality of wave-length;
a multiplexer coupled to an input of said emit-ters, wherein each said emitter is coupled to a carrier signal comprising a sum of at least n carrier components;
a detector disposed to receive energy from said modulating medium; and a demultiplexer coupled to an output of said detector, wherein an output of said demutliplexer indi-cates absorption by the modulating medium at said plural-ity of wavelengths.
a multiplexer coupled to an input of said emit-ters, wherein each said emitter is coupled to a carrier signal comprising a sum of at least n carrier components;
a detector disposed to receive energy from said modulating medium; and a demultiplexer coupled to an output of said detector, wherein an output of said demutliplexer indi-cates absorption by the modulating medium at said plural-ity of wavelengths.
36. A device as in claim 35, wherein each said car-rier signal is a time-varying periodic signal with identi-cal period.
37. A method of collecting photoplethysmographic data, comprising the step of generating a first a second signal, each comprising a set of component signals, said first and second signals being distinguishable by amplitudes of said component signals;
applying said first and second signals to a modulating medium;
detecting a composite signal at an output of said modulating medium, said modulating medium having a first and a second modulating effect; and generating a first and a second output signal responsive to said composite signal, said first output signal indicating said first modulating effect and said second output signal indicating said second modulating effect.
applying said first and second signals to a modulating medium;
detecting a composite signal at an output of said modulating medium, said modulating medium having a first and a second modulating effect; and generating a first and a second output signal responsive to said composite signal, said first output signal indicating said first modulating effect and said second output signal indicating said second modulating effect.
38. A method as in claim 37, wherein said first and second signals are periodic time-varying signals with identical periods.
39. A method as in claim 37, wherein said first and second signals have identical frequency components.
40. A method as in claim 37, wherein said modulating medium comprises animal tissue.
41. A method as in claim 37, wherein said modulating medium comprises at least one of the group: blood, blood vessels, bone marrow, ligament, muscle, skin.
42. A method as in claim 37, wherein said composite signal comprises a sum of said first modulating effect applied to said first signal and said second modulating effect applied to said second signal.
43. A method of collecting photoplethysmographic data, comprising the steps of generating a plurality of carrier signals, each comprising a set of component signals, said carrier sig-nals being distinguishable by amplitudes of said component signals;
detecting a composite signal at an output of said modulating medium, said modulating medium having a plurality of modulating effect; and generating a plurality of output signals respon-sive to said composite signal, each said output signal indicating one said modulating effect.
detecting a composite signal at an output of said modulating medium, said modulating medium having a plurality of modulating effect; and generating a plurality of output signals respon-sive to said composite signal, each said output signal indicating one said modulating effect.
44. A method of collecting photoplethysmographic data, comprising the steps of multiplying a mixing matrix and a vector of component signals;
applying a plurality of modulating effects to a resultant of said step of applying.
applying a plurality of modulating effects to a resultant of said step of applying.
45. A method as in claim 37 or 44, wherein said photoplethysmographic data comprises blood gas data.
46. A method as in claim 37 or 44, wherein said photoplethysmographic data comprises at least one of the group: blood oxygen, blood carbon dioxide, blood carbon monoxide.
47. A method as in claim 44, wherein said mixing matrix is a square matrix.
48. A method as in claim 37 or 44, wherein at least one of said component signals comprises a sum of at least one of the group: a sine wave, a square wave.
49. A method as in claim 37 or 44, wherein at least one of said modulating effects comprises amplitude modulation.
50. A method as in claim 37 or 44, wherein said modulating effects comprise an amplitude modulation effect which varies with energy wavelength.
51. A method as in claim 37 or 44, wherein at least one of said modulating effects comprises a time-varying component.
52. A method as in claim 37 or 44, wherein at least one of said modulating effects comprises a time-varying component which is correlated with a biological process.
53. A method as in claim 37 or 44, wherein at least one of said modulating effects comprises at least one transmission response of a modulating medium.
54. A method as in claim 44, comprising the steps of detecting a composite resultant of said step of applying; and separating said composite resultant into a vec-tor resultant.
55. A method as in claim 54, wherein said step of separating comprises at least one hetrodyning step.
56. A method as in claim 54, wherein said composite resultant comprises a sum of at least two elements of said vector resultant.
57. A method of collecting photoplethysmographic data, comprising the steps of component-amplitude-division multiplexing a plurality of modulating signals; and component-amplitude-division demultiplexing said plurality of signals.
58. A method as in claim 57, wherein each said modu-lating signal comprises a modulating effect.
59. A method as in claim 57, wherein said plurality of modulating signals comprises an infrared wavelength modulating signal and a red wavelength modulating signal.
60. A method in claim 57, wherein said step of component-amplitude-division multiplexing and said step of component-amplitude-division demultiplexing collectively comprise a step of error detection.
61. A method as in claim 57, wherein said step of component-amplitude-division multiplexing and said step of component-amplitude-division demultiplexing collectively comprise a step of error correction.
62. A method as in claim 61, wherein said step of error correction comprises majority voting a resultant of component-amplitude-division multiplexing and demultiplex-ing with a plurality of mixing matrices.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/665,595 | 1991-03-05 | ||
| US07/665,595 US5349953A (en) | 1991-03-05 | 1991-03-05 | Photoplethysmographics using component-amplitude-division multiplexing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2062249A1 true CA2062249A1 (en) | 1992-09-06 |
Family
ID=24670741
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002062249A Abandoned CA2062249A1 (en) | 1991-03-05 | 1992-03-04 | Photoplethysmographics using component-amplitude division multiplexing |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5349953A (en) |
| CA (1) | CA2062249A1 (en) |
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| US8364220B2 (en) | 2008-09-25 | 2013-01-29 | Covidien Lp | Medical sensor and technique for using the same |
| US8423112B2 (en) | 2008-09-30 | 2013-04-16 | Covidien Lp | Medical sensor and technique for using the same |
| US8417309B2 (en) | 2008-09-30 | 2013-04-09 | Covidien Lp | Medical sensor |
| US8914088B2 (en) | 2008-09-30 | 2014-12-16 | Covidien Lp | Medical sensor and technique for using the same |
| US8452366B2 (en) | 2009-03-16 | 2013-05-28 | Covidien Lp | Medical monitoring device with flexible circuitry |
| US8221319B2 (en) | 2009-03-25 | 2012-07-17 | Nellcor Puritan Bennett Llc | Medical device for assessing intravascular blood volume and technique for using the same |
| US8509869B2 (en) | 2009-05-15 | 2013-08-13 | Covidien Lp | Method and apparatus for detecting and analyzing variations in a physiologic parameter |
| US8634891B2 (en) | 2009-05-20 | 2014-01-21 | Covidien Lp | Method and system for self regulation of sensor component contact pressure |
| US9010634B2 (en) | 2009-06-30 | 2015-04-21 | Covidien Lp | System and method for linking patient data to a patient and providing sensor quality assurance |
| US8505821B2 (en) | 2009-06-30 | 2013-08-13 | Covidien Lp | System and method for providing sensor quality assurance |
| US8311601B2 (en) | 2009-06-30 | 2012-11-13 | Nellcor Puritan Bennett Llc | Reflectance and/or transmissive pulse oximeter |
| US8391941B2 (en) | 2009-07-17 | 2013-03-05 | Covidien Lp | System and method for memory switching for multiple configuration medical sensor |
| US8417310B2 (en) | 2009-08-10 | 2013-04-09 | Covidien Lp | Digital switching in multi-site sensor |
| US8428675B2 (en) | 2009-08-19 | 2013-04-23 | Covidien Lp | Nanofiber adhesives used in medical devices |
| US8666468B1 (en) | 2010-05-06 | 2014-03-04 | Masimo Corporation | Patient monitor for determining microcirculation state |
| US9066666B2 (en) | 2011-02-25 | 2015-06-30 | Cercacor Laboratories, Inc. | Patient monitor for monitoring microcirculation |
| US10463315B2 (en) * | 2014-12-01 | 2019-11-05 | Covidien Lp | Adaptive alarm for physiological monitoring |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4653498A (en) * | 1982-09-13 | 1987-03-31 | Nellcor Incorporated | Pulse oximeter monitor |
| BR8707578A (en) * | 1986-12-12 | 1988-12-06 | Mark Yelderman | APPARATUS AND PROCESS FOR NON-INVASIVELY MEASURING THE CONCENTRATION OF A BLOOD CONSTITUENT |
| JPS63277039A (en) * | 1987-05-08 | 1988-11-15 | Hamamatsu Photonics Kk | Diagnostic apparatus |
-
1991
- 1991-03-05 US US07/665,595 patent/US5349953A/en not_active Expired - Lifetime
-
1992
- 1992-03-04 CA CA002062249A patent/CA2062249A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US5349953A (en) | 1994-09-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |