CA1326801C - Nasogastric device - Google Patents

Abstract

ABSTRACT

Nasogastric intubation device having a removable stylet or stiffening wire to facilitate proper intubation, wherein the stylet is provided with a surface coating consisting essentially of alkaline earth metal salts of an unsaturated and a saturated higher fatty acid containing at least 16 carbon atoms.

Description

.~ 1326801 NOVEL NASOGASTRIC DEVICE

~ACKGROUND OF THE INVENTION
Thls lnventlon relates to lmprovements ln nasogastrlc lntubatlon devlces adapted for feedlng and/or removal of flulds from the stomach. As ls well known, nasogastrlc devlces are commonly employed ln postoperatlve abdomlnal surgery for empty-lng the stomach of secretlons and gas ln order to prevent gastrlc dllatlon. They are also used for attalnlng adequate nutrltlon, e.g. feedlng of hlgh proteln llqulds, for patlents unable to take oral nourlshment. Nasogastrlc lntubatlon may be prescribed, for example, when the normal dlgestlve mechanlsm ls lmpalred. Impalrment may range from locallzed trauma to the dlgestlve tract to loss of automlc functlon, a common slde effect for stroke vlctlms.
Whether lntubatlon be for asplratlon or removal of flulds from the stomach or for feedlng, lntubatlon ls accom-pllshed by lnsertlng the nasogastrlc tube lnto a nostrll and dlrectlng lt through the esophagus to the stomach and/or small lntestlne lf the stomach ls dlsfunctlonal.
In dlrectlng the tube, anatomlcal angulatlons as well as crltlcal blfurcations of the pathway mandate a seml-rlgld ob~ect. Mlsguldlng a nasogastrlc tube lnto the trachea rather than the esophagus, at the orophagngeal blfurcatlon can result ln resplratory lmpalrment, e.g. pneumothorax or puncturlng of the lung. Consequently, some degree of rlgldlty ls needed for proper guldance durlng lntubatlon.
Paradoxlcally, however, a rlgld lntubatlon devlce can produce a dlfferent category of ln~urles, namely soft tlssue ln~urles to the dellcate mucosal llnlng as well as to the slnuses, eplglottls, uvula, larynx, etc. Dlrect lmpact or frlction caused durlng lntubatlon or removal may cause abra-slons and/or hemorrhaglng. Laryngltls and dlfflculty ln swallowlng are among the most frequently reported post-lntubatlon compllcatlons, lllustratlng the lnadequacy of the devlces presently used.
It will therefore be seen that a nasogastrlc tube should be flexlble to minimlze lmpact and frlctlon. On the other hand, accurate and safe guldance necessltates a rlgld ob~ect, whlch rlgldity can cause ln~ury to soft tlssues. Whlle the prlor art has addressed thls paradox, lt has not done so successfully.
Generally ~peaklng, two nasogastrlc lntubatlon proce-dures are presently domlnant. The flrst method, whlch seeks to obvlate the aforementloned paradox, but ls less common, utlll-zes a flexlble tube whlch ls swallowed. Thls method relles upon a vlable and functlonal swallowlng mechanlsm, lmpalrment of whlch ls a reason for prescrlblng lntubatlon ln the flrst place. Accordlngly, thls technlque has llmlted appllcablllty.
The second and generally accepted procedure employs a stylet or wlre gulde to facllltate lntubatlon. In thls form of nasogastrlc lntubatlon, the stylet ls lnltlally housed ln the tube and ls removed once proper posltlonlng ls obtalned.
The present lnventlon ls dlrected to the latter devlce employlng a stylet or stlffenlng wlre gulde to facill-tate proper lntubatlon, and, more partlcularly, to a novel coatlng for the stylet to facllltate removal wlthout dlslodg-ment or movement of the tube.
As wlll be appreclated, a nasogastrlc tube follows a rather tortuous path from lnsertlon ln the nasal passage and then down through the esophagus and eventually lnto the stom-ach. Because of the varlous angulatlons and the frlctlonal forces resultlng therefrom when the stylet contacts the lnner wall of the tube durlng removal, soft tlssue ln~urles wlll frequently occur.
The prlor art has attempted to address thls problem by proposlng varlous coatlngs and/or lubrlcants to decrease frlctlon and thereby lessen the danger of ln~ury. ~owever, none has been entlrely satlsfactory.
Whlle not lntendlng to be an exhaustlve survey of the ~ 1326801 prlor llterature pertaining thereto, the following patents are nevertheless consldered to be falrly lllustratlve of the state of the art pertainlng to tubes havlng gulde wlres lntended to be removed once the tube ls ln place.
U.S.P. 4,257,921 of Beal proposes the use of Teflon coated wlres.
U.S.P. 4,534,363 lssued to Gold teaches uslng copoly-mers of methyl slloxane and amlno alkyl slloxane.
U.S.P. 4,58g,873 of Schwartz dlscloses hydrophlllc polymers and PVC tu~lng coated wlth PVP, polyethylene oxide, polyhydroxyethyl methacrylate, copolymers of PVP wlth vlnyl sulfonlc acld or other vlnyl aclds.
U.S.P. 4,664,657 of Wlllamltls teaches uslng polydl-methyl slloxane.
U.S.P. 4,666,437 of Lambert dlscloses applylng to an artlcle made of vlnyl polymers, polyesters or polyacrylates and rubber, a solutlon of an lsocyanate monomer havlng at least two unreacted lsocyanate groups per molecule, an lsocyanate pre-polymer, or a mlxture thereof.
U.S.P. 4,668,224 lssued to Lentz teaches the use of a cellulose powder, e.g. acld cellulose.
Finally, British Speciflcatlon 1,600,963 teaches using an interpolymer of PVP and polyurethane.
As prevlously mentloned, none of the coatings or lubrlcants heretofore suggested have been entirely satisfactory for use with nasogastrlc tubes.
Accordingly, the task of thls lnventlon, slmply stat-ed, 15 to provlde lubrlclous coatings for stylets utilized for lntubatlon, whlch coatlngs employ readlly avallable and rela-tively lnexpensive materlals to provide the requislte lubri-clousness for easy removal from the tube.

*Trade-mark 3 ~ 1326801 BRIEF DESCRIPTION OF THE INVENTION
In accordance wlth the present lnvention, thls task ls solved by utlllzlng as the lubrlcatlng coatlng for the sty-let a substantlally homogeneous non-aqueous ml~ture conslstlng essentially of:
(1) an alkaline earth metal salt of an unsaturated hlgher fatty acld havlng at least 16 carbon atoms; and (2) up to equal parts by welght of an alkallne earth metal salt of a saturated fatty acld havlng at least 16 carbon atoms.
Upon applylng an aqueous medlum, e.g. by flushlng the stylet-contalnlng nasogastrlc tube wlth water, a lubrlclous coatlng is provlded on the stylet whlch materially enhances removal of the stylet followlng ln~ubatlon along wlth a concom-ltant lessenlng of the danger of lnadvertent or accldental movement or partlal dlslodgment of the tube from the stomach durlng stylet removal.

BRIEF DESCRIPTION OF THE DRAWING
The flgure ls a perspectlve vlew of a typlcal naso-gastrlc tube to whlch thls lnventlon ls dlrected wlth the sty-let partlally removed for purposes of lllustratlon.

DETAILED DESCRIPTION OF THE INVENTION
As prevlously stated, the present inventlon ls dlrected to reduclng the frlctlonal forces encountered ln attemptlng to remove the stylet or stlf~enlng wlre from naso-gastrlc tubes followlng lntubatlon for feedlng, asplratlon and/or removal of stomach flulds.
Nasogastrlc devlces are of course well known ln the medlcal and surglcal arts and a typlcal devlce of thls descrlp-tlon ls shown ln the lllustratlve drawlng.
As ls lllustrated thereln, nasogastric tube 10, asoft, hollow tublng, has a welghted bolus 12, e.g. a tungsten-welghted bolus, attached to lts leadlng end to help malntaln i32~801 644~7-116 lntubatlon and placement. The opposed or tralling end of tube 10 ls secured to hollow cone-shaped tube connector 14. A
braided stlffenlng wlre 16 extends from the leadlng end of tube 10 to where the wlre ls secured at lts tralllng end to stylet connector 18 adapted to be removably seated wlthln openlng 14a of the tube connector. The top or tralllng end of stylet con-nector 18 has a flushlng port 20 adapted for applylng water to lubrlcate the stylet, as wlll be descrlbed more fully hereln-after.
At the leadlng end of tube 10 a pair of opposed open-lngs ln the tube wall or "feedlng ports" are provlded, one of whlch, 22, ls shown ln the drawlng.
A palr of "ears" or extendlng flexlble bars 24a and 24b extend on elther slde of tube connector 14. Ear 24a has a hollow cone-shaped member 26 adapted to be removably seated wlthln openlng 14a, by flexlng ear 24a, once the stylet and stylet connector are removed. Ear 24b has a solld plug 28 adapted to be lnserted ln the openlng ln member 26 when the tube ls not in use for fluid transmlttal.
In operation, ~ust prior to insertlon, the stylet ls lubrlcated by flushlng the tube through port 20 wlth water, e.g. 10-15 cc's of water. The bolus tlp ls then coated wlth a surglcal lubrlcant, e.g. a lubrlcatlng ~elly containlng phenyl mercurlc borate. The tube ls then gently inserted lnto the nostrll, almlng down and back toward the ear.
As the bolus drops off back of the soft palate lnto the pharynx, the patlent ls encouraged to swallow, lf possible.
Glvlng the patlent small amounts of water to sip through a straw ls sometlmes helpful, lf not contralndlcated.
The practltloner then contlnues to gently asslst the tube passage down the esophagus and lnto the stomach untll the deslred posltion ls reached. In dolng so, cautlon must be exerclsed not to use force. One must proceed slowly and care-fully. Sllght gagglng ls normal. However, lf the patlent coughs or cannot vocallze or shows slgns of resplratory dls-132~801 tress, thls may indicate that the tube has lnstead entered the trachea. If this occurs, the tube must be withdrawn and inser-ted lnto the esophagus.
Before withdrawing the wire stylet, assurance that the tube has reached the deslred posltlon is obtalned by one or all of the followlng methods: (a) ausculatlon, e.g. by in~ec-tlng wlth a syrlnge 10-20 cc of alr through tube/stylet assem-bly and llstenlng for a bubbllng sound ln the upper left ab-domlnal quadrant; (b) asplratlon by uslng a syrlnge to wlthdraw a small amount of gastrlc contents; or (c) X-ray.
When the tube ls properly posltloned, slowly and carefully wlthdraw the stylet from the tube. If reslstance ls felt, flush the lumen agaln wlth water (as descrlbed above) and the stylet ls then twlsted before attemptlng further wlth-drawal. [If reslstance ls stlll felt, the nurse or other medlcal asslstant ls then lnstructed to stop and consult a physiclan, thux conflrmlng and relnforclng the prevlous dls-cusslon wlth respect to the lnadequacy of prlor stylet lubrl-catlng procedures.]
After the stylet ls removed, the tube may be closed off wlth members 26, 28, lf deslred. The tube ls then taped to the patlent's nose to stablllze. It ls preferably also anchor-ed to the cheek or forehead, avoldlng dlstortlon of, or pres-sure on, the nares.
In accordance wlth thls lnventlon, lmproved lubrlc-iousness of the stylet and, ln turn, materlally lncreased re-slstance to frlctlonal forces ls obtalned by coating the stylet wlth a substantially homogeneous composltlon conslstlng essen-tlally of an alkallne earth metal salt of an unsaturated hlgher fatty acld havlng at least 16 carbon atoms and as much as equal parts by welght of an alkallne earth metal salt of a saturated hlgher fatty acid havlng at least 16 carbon atoms.
Because of cost and avallablllty, the unsaturated acld salt should be elther mono- or dl-un~aturated. For the same reason, the salts of olelc or llnolelc acld are preferred.

132~8~1 64407-116 Preferably, the alkallne earth metal salt wlll be sodlum or potassium, e.g. sodlum or potasslum oleate or linoleate.
In like manner, the salts of stearlc or palmltlc acld are preferred for the saturated fatty acld salt component of the lubrlclty-provldlng coatlng.
In the coatlng composltlons of thls lnventlon, the effectlve lngredlent for provldlng the deslred lubrlclty ls the unsaturated fatty acld soap, e.g. sodlum oleate. However, slnce these unsaturated soaps are soft, flaky sollds ln pure form, they cannot be used alone as the coatlng materlal.
Accordingly, another component ls needed as a vehlcle for and/or modlfler of the propertles of the unsaturated soap ln order to provlde a proper coatlng on the stylet surface.
In theory, varlous per se known compatlble vehlcles could concelvably be employed for coatlng thls soap, e.g. poly-vlnyl alcohol, gelatln, cellulose esters such as carboxymethyl cellulose, and other such commonly used materlals. However, when such vehlcles are utlllzed, the soap tends to wash off qulckly upon appllcatlon of water through the flushlng port and accordlngly the requlslte lubrlclous coatlng ls not obtalned.
Accordlngly, a crltlcal aspect of the present lnven-tlon ls the dlscovery that uslng up to equal parts by welght of a saturated hlgher fatty acld salt in comblnatlon wlth the lubriclty-provlding unsaturated fatty acld soap modlfles the coatlng composltlon so as to provlde the approprlate propertles for the contemplated usage of asslstlng removal of the stylet followlng lntubatlon. Speclflcally, ln addltlon to belng com-patlble wlth the soap so as to form a substantlally homogeneous mlxture, the saturated fatty acld salt lncreases the coheslve strength of the coatlng composltlon and ralses lts meltlng polnt, thus making lt harder.
While, as mentloned prevlously, up to equal parts by welght of the saturated fatty acld soap may be employed, l.e.
1:1 by welght mlxture of the two salts, ln the preferred em-bodlments, the ratlo by welght of the unsaturated soap to the 1326~01 saturated salt wlll be no less than about 4:1. In general, ln the preferred embodlments, the coatlng composltlon wlll conslst essentlally of from about 80 to about 90% by welght of the un-saturated soap, the remalnder belng the saturated fatty acld salt.
The coatlng compositlon may be applled to the stylet from an organlc solutlon by spraylng, flowlng, lmmerslng or other per se known coatlng technlques. The preferred solvents for thls purpose are ethanol and methanol.
The followlng examples show by way of lllustratlon and not by way of llmltatlon the practlce of thls lnventlon.

Two grams of stearlc acld were dlssolved ln elght grams of olelc acid and the resultlng mlxture was then dls-solved ln two volumes of ethanol. Phenolphthaleln pH lndlcator was added ln order to vlsuallze the end polnt of neutral pH.
Four molar sodlum hydroxlde was then added at 50-55C wlth stlrrlng untll the end polnt was reached. The solutlon was now plnk and very sllghtly alkallne. The stylet wlre from a naso-gastrlc lntubatlon devlce as shown ln the drawlng was lmmersedln the resultlng alcohollc solutlon whlle malntalnlng the tem-perature of around 50-55C. The wlre was then removed and alr drled. The resultlng coated wlre and tube were then assembled to provlde a nasogastrlc lntubatlon devlce as shown ln the drawlng and prevlously descrlbed.

Example 1 was repeated, except that one gram of stearlc acld and nlne grams of olelc acld were dlssolved ln methanol.
In both of the above examples, the coatlng on the stylet was appreciably harder than the coatlng obtalnable wlth the oleate alone. The coatlngs dld not flake or rub off when the stylet was lnserted ln the tube, as was the case wlth the ~ ~32~801 oleate alone.
The nasogastrlc tube as prepared above may be employ-ed ln the manner heretofore described. In other words, prior to lnsertlon, the devlce wlll be flushed wlth a small quantlty of water, as prevlously descrlbed, to provlde ln effect a soap solution lubrlcating the wlre surface ln order to provlde a substantial decrease ln frlctlon and, ln turn, permlt easy removal of the wlre after lntubatlon ls completed.
It wlll of course be appreclated that the bolus should also be lubrlcated prlor to lnsertlon, whlch lubrlcatlon may be accompllshed wlth the ald of a surglcal lubrlcant, as prevlously descrlbed. Preferably, however, lubrlcatlon of the bolus ls accompllshed by provldlng a lubrlclous precursor con-slstlng essentlally of a substantlally unlform mlxture of an unsaturated hlgher fatty acld contalnlng at least slxteen carbon atoms and a polymer such as polyurethane whlch ls com-patlble therewlth, ln accordance wlth the lnventlon descrlbed and clalmed ln our concurrently flled Canadlan patent appll-catlon, Serlal No. 594,732. As ls descrlbed thereln, when the bolus provlded wlth the above composltlon ls contacted wlth an aqueous alkallne medlum, the surface of the bolus ls rendered lubrlclous. When the present lnventlon ls used ln con~unctlon wlth the lnventlon descrlbed and clalmed ln the aforementloned copendlng appllcatlon, lt wlll be appreclated that ln lleu of utlllzlng water at a neutral pH ln the flushlng port, a sllght-ly alkallne aqueous solutlon, e.g. on the order of pH 8.5-9 wlll be utlllzed ln order to convert the acld ln the bolus to lts soap and thereby lubrlcate both the wlre and bolus ln a slngle step.
To conflrm the efflcacy of thls lnventlon, compara-tlve tests were run to establlsh the removal force for (1) a dry uncoated stylet wlre; (2) a wet uncoated stylet wlre; (3) a dry stylet wlre coated as ln Example 2; and (4) a stylet wlre coated as ln Example 2 and whlch has been wetted wlth water.
In these tests, an approxlmately 7 cm unsupported loop was made ln the stylet-contalnlng tube ln order to provlde some frlctlon slmulatlng actual removal condltlons. Wlth both the dry un-coated wlre ~1) and the wet uncoated wire (2), the wlre could not be removed. Wlth the dry wlre coated ln accordance wlth thls lnventlon (3) 50 grams of force was requlred for removal.
However, when the coated wlre was wetted (4) only 37 grams of force was needed, thus conflrmlng the ablllty of the present lnventlon to solve the task of the lnventlon ln a slmple and elegant manner, namely to provlde a lubrlclous coatlng on the stylet whlch materlally lmproves the surface lubrlclty so as to facllltate markedly the removal of the wlre from the tube fol-lowlng lntubatlon.
Slnce certaln changes may be made wlthout departlng from the scope of the lnventlon hereln lnvolved, lt ls lntended that all matter descrlbed ln the foregolng speclflcatlon and drawlng shall be lnterpreted as lllustratlve and not ln a limltlng sense.

Claims (10)

1. A flexible stylet adapted for being removably inserted within a nasogastric tube in order to assist in intubation, said stylet having a surface coating of a substantially homogeneous non-aqueous mixture consisting essentially of an alkaline earth metal salt of an unsaturated higher fatty acid having at least sixteen carbon atoms; and up to equal parts by weight of an alkaline earth metal salt of a saturated fatty acid having at least sixteen carbon atoms.

2. A stylet as defined in Claim 1 wherein said unsaturated fatty acid is oleic or linoleic acid.

3. A stylet as defined in Claim 2 wherein said saturated fatty acid is stearic or palmitic acid.

4. A stylet as defined in Claim 3 wherein the ratio by weight of said unsaturated fatty acid salt to said saturated fatty acid salt is no less than about 4:1.

5. A stylet as defined in Claim 1 wherein said mixture contains from about 80 to about 90 per cent by weight of said unsaturated fatty acid salt.

6. A nasogastric intubation device including a tube adapted to be inserted through the nose and into the stomach, said tube having a leading end for positioning in the stomach and a trailing end, said tube having at least one port adjacent its leading end for passage of fluid to or from said tube; and a flexible stylet removably insertable into said trailing end of said tube to assist in intubation, said stylet having a sur-face coating of a substantially homogeneous non-aqueous mixture of an alkaline earth metal salt of an unsaturated higher fatty acid having at least sixteen carbon atoms; and up to equal parts by weight of an alkaline earth metal salt of a saturated fatty acid having at least sixteen carbon atoms.

7. A device as defined in Claim 6 wherein said unsatura-ted fatty acid is oleic or linoleic acid.

8. A device as defined in Claim 7 wherein said saturated fatty acid is stearic or palmitic acid.

9. A device as defined in Claim 8 wherein the ratio by weight of said unsaturated fatty acid salt to said saturated fatty acid salt is no less than about 4:1.

10. A device as defined in Claim 6 wherein said mixture contains from about 80 to about 90 per cent by weight of said unsaturated fatty acid salt.