Self-arresting overpenetration-proof cannula device for body cavities

A self-arrest overpenetration-proof cannula device for the safe insertion of a cannula or a needle with or without a catheter concentric to it into any body cavity or anatomical hollow structure having a wall, said body cavity or hollow structure being either naturally present or pathologically formed, being fluid, air or gas filled. The device has the intrinsic ability of automatically arresting the advancement of a needle or cannula instantly upon occurred body cavity penetration by the tip of said needle or cannula. The device is capable of recognizing penetration of a body cavity by means of a dropping of a vacuum pressure present in the device prior to body cavity penetration, said dropping of vacuum pressure occurring upon body cavity penetration of the needle tip, and is able to automatically respond to said drop of vacuum pressure by arresting the advancement of the needle or cannula.

BACKGROUND--FIELD OF THE INVENTION 
This invention relates to medical devices apt to access body cavities more 
specifically to medical- surgical devices, such as surgical cannulas or 
needles or catheters-needles assemblies apt to access percutaneously body 
cavities of patients for therapeutic or diagnostic indications. 
BACKGROUND--FIELD OF THE INVENTION 
Placing a surgical cannula or needle with or without a catheter into a body 
cavity of a patient for either diagnostic or therapeutic purposes, by 
accessing said body cavity via the percutaneous route is a fairly common 
medical-surgical procedure. We list the most common procedures: 
Needle-cricothyroidotony, Abdominal paracentesis, Diagnostic Peritoneal 
Lavage, Pleurocentesis or Thoracentesis, Pericardiocentesis, 
Arthrocentesis, Needle thoracostomy and Closed thoracostomy, Lumbar 
puncture, Subdural Aspiration in infants, Abscess aspiration, 
Amniocentesis, Culdocentesis, Suprapubic Bladder catheterization and 
Aspiration, Fluid-filled Cyst Aspiration, Hematoma evacuation, Blood 
drawing ,etc. 
In all the above mentioned procedures a hollow needle or surgical cannula 
is placed by the operator within the desired anatomical space, i.e. a body 
cavity, naturally present or pathologically formed, either gas or air or 
fluid filled, for diagnostic or therapeutic purposes. In some of the above 
procedures a catheter usually flexible concentric to the surgical cannula 
or the hollow needle can be placed into the body cavity, after the body 
cavity has been penetrated by the cannula or needle, and sometimes such 
catheter may even be left in place, for instance for evacuation and 
drainage of the fluid contained within the body cavity. 
Placing a surgical cannula or needle into a body cavity carries definite 
risks for the patient. Risks and complications are mainly due to 
overpenetration by the cannula or needle. Overpenetration can cause damage 
to the healthy surrounding tissues and organs. The severity of the 
iatrogenic injuries caused by an overpenetrating surgical cannula or 
needle is largely dependent upon the anatomical location of the body 
cavity to be accessed. The more vital and delicate are the anatomical 
structures in proximity of the body cavity to be accessed, the higher the 
risks of the procedure. 
For instance the procedure of Pericardiocentesis or Needle Aspiration of 
fluid from the pericardium for either diagnostic or therapeutic reasons 
carries obvious definite risks for the patient. "Placing a needle or 
catheter into the pericardial space should be performed only by a skilled 
and experienced physician." Textbook of Advanced Cardiac Life Support, 
American Heart Association, second edition, page 199. Overpenetration 
means almost certain severe injury to the myocardium, possible laceration 
of coronary arteries, and possible death of the patient. It is of 
paramount importance that the operator recognizes pericardial space 
penetration by the advancing needle at the earliest stage of said 
penetration in order to arrest immediately the advancement of the needle. 
Same considerations can be made for many of the procedures above listed 
such as Needle Cricothyroidotomy in which a cannula with or without a 
catheter is placed within the trachea, accessing it via the percutaneous 
route, or Amniocentesis in which a needle is placed within the amniotic 
sac for aspiration of amniotic fluid. 
The most critical factor for the operator for the successful completion of 
all the procedures of placement of a surgical cannula or needle with or 
without catheter into a body cavity is the immediate arrest of the needle 
advancement upon ascertainment of body cavity penetration by the tip of 
the needle. When a catheter-needle assembly is being used, catheter 
advancement into the body cavity is carded out by sliding the catheter 
over the needle only after ascertainment of penetration of the body cavity 
by the tip of the needle. 
In order to facilitate ascertainment of the occurred penetration of the 
body cavity by the needle tip, the operator preferably connects a syringe 
to the needle or cannula and by withdrawing the plunger of the syringe 
after the tip of the needle or cannula has been inserted into the skin or 
tissues overlaying the body cavity, he, or she, aspirates constantly 
during the advancement and passage of the cannula or needle through the 
tissues or walls overlying the body cavity, creating a negative pressure, 
within the syringe ahead of the plunger, which results in a resistance to 
withdrawal of the plunger. When the tip of the needle, passing through the 
tissues overlying the body cavity, enters the body cavity, air or fluid is 
aspirated into the syringe connected to the needle or cannula and, as a 
result of that, the negative pressure in front of the plunger suddenly 
drops and, consequently, the resistance to withdrawal of the plunger being 
held by the operator suddenly falls. The fall of resistance to withdrawal 
of the plunger alerts the operator of the occurred body cavity 
penetration. At this point the operator promptly arrests the advancement 
of the needle or cannula in order to avoid overpenetration and damage to 
the surrounding tissues with possible dreadful consequences, local and 
systemic, for the patient. 
From the above description of the procedure, it is apparent that the 
following procedural steps are critical for the operator: 
1) To ascertain body cavity penetration at the earliest stage of 
penetration by the needle tip of the cannula or needle, and 
2) To arrest the needle advancement immediately, as soon as body cavity 
penetration is ascertained. 
A search in the Patent Office has revealed no surgical cannula or needle 
capable of sensing body cavity penetration and self arrest of the 
advancing needle in response to body cavity penetration based on the 
principle outlined below. 
BRIEF SUMMARY OF THE INVENTION 
The disadvantages of the present apparatus and methods of cannula or needle 
placement into a body cavity are overcome with the present invention. 
With the present application we propose a Self-arresting Overpenetration 
Proof Cannula Device. Our device is able to place a surgical cannula or 
needle into a body cavity without the risk inherent to the devices and 
methods presently used. 
The principle our device is based upon is the intrinsic ability of the 
device to automatically respond with a self-arresting mechanism stopping 
the advancement of the needle or cannula instantly upon occurred body 
cavity penetration by the tip of the needle or cannula. The device is 
capable of recognizing penetration of a body cavity by means of a dropping 
of a vacuum pressure present in the device prior to body cavity 
penetration, said dropping of vacuum pressure occurring upon body cavity 
penetration of the needle tip, and is able to automatically respond to 
said drop of vacuum pressure by arresting the advancement of the needle or 
cannula. No known device is capable to do so based in the above outlined 
principle. 
With our device, the operator, after arming the device by creating a vacuum 
pressure at the proximal end of the needle or cannula, advances the needle 
or cannula through the tissues overlying the body cavity. The device, as 
outlined above, instantly recognizes body cavity penetration by the needle 
tip and it is capable of instantly and automatically arresting any further 
advancement of the needle or cannula avoiding any risks of 
overpenetration. 
Subsequent optional advancement of a catheter over the cannula or needle at 
the earliest time of said penetration is achieved either automatically in 
a preferred embodiment, or manually. 
Risks and complications due to overpenetration of the advancing needle with 
our device are practically non existing. 
The advantages of the present invention are preferably attained by a self 
arresting overpenetration proof cannula device comprising a cannula or 
needle, with or without a catheter concentric with said cannula or needle, 
means sensing body cavity penetration by said cannula or needle and means 
arresting the advancement of said cannula or needle automatically upon 
penetration of the body cavity by said penetrating needle. 
When a catheter-needle assembly is used, the device is also provided with 
manual or resilient means urging said catheter to an advanced position and 
means for triggering the resilient means of catheter advancement into a 
body cavity upon body cavity penetration. The triggering means releasing 
catheter advancement may be manual or may be fully automatized in response 
to body cavity penetration of the needle tip. 
Another object of the present invention is to provide an improved 
Self-arresting Cannula Device which permits one handed insertion and 
placement of a cannula, needle or catheter within any body cavity without 
risk for the patient. 
Another object of the present invention is to provide the operator with a 
safe Self-arresting Cannula Device which includes means of controlled 
penetration and arrest of the cannula or needle advancement into any body 
cavity entirely obviating to reliance upon potentially failing human 
factors which could lead to overpenetration and damage to the tissues and 
organs surrounding body cavities.

DETAILED DESCRIPTION OF THE DEVICE 
FIG. 1 is a side view of the device, generally indicated at 1000 in a stage 
prior to use. The device is composed of three main parts: a housing 1002, 
a cannula or needle 1004, and a catheter 1006. 
As best seen in FIG. 2, which is a cross section of the device prior to 
use, housing 1002 is composed of two parallel chambers of generally 
cylindrical shape, piston chamber 1008, interface member chamber 1010 and 
of an arresting unit or means 1100. 
Needle hub 1005 connected to housing 1002, protrudes from anterior lower 
end 1007 of housing 1002. Needle hub 1005 has base 1011 which precisely 
fits within catheter hub 1009 of catheter 1006 and has nozzle 1013 in 
continuity with needle hub base 1011 to allow adequate leeway for release 
of catheter hub 1009 of catheter 1006 from hook 1082 of front end 1060 of 
intermediate member 1044, when catheter 1006 is advanced as it will be 
described in the description of the operation. 
Piston chamber 1008, delimited laterally by sidewall 1041, is composed of 
an anterior or vacuum chamber 1012 in communication with hollow needle 
1004, and a posterior chamber 1014 of larger diameter than vacuum chamber 
1012. Posterior chamber 1014 is in continuity of vacuum chamber 1012 via 
opening 1026, with collar 1028 encircling opening 1026. Posterior chamber 
1014 is open posteriorly via opening 1030. In piston chamber 1008 is 
slideably mounted piston 1016. Piston 1016 is composed of three segments: 
anterior segment 1018, intermediate segment 1032 and posterior segment 
1038. Anterior segment 1018 is partially contained in vacuum chamber 1012 
and partially in posterior chamber 1014. The anterior segment 1018 of 
piston 1016 has an annular groove 1020 formed in proximity of its front 
end 1022, where O-ring 1024 is mounted in airtight fashion with wall 1025 
of vacuum chamber 1012. Spring 1040 is mounted around anterior piston 
segment 1018, between collar 1028 and flange 1042 of intermediate piston 
segment 1032. The intermediate segment 1032 of piston 1016, in continuity 
with anterior piston segment 1018, is of larger diameter than anterior 
piston segment 1018 in order to fit in chamber 1014 of larger diameter. 
Intermediate piston segment 1032 has front face 1045, posterior face 1047 
and side face 1043. As better seen in FIG. 3, intermediate piston segment 
1032 from back to front is formed with posterior flange 1079, annular 
recess 1076 for trigger member 1070, wide annular recess 1034 for ball 
member 1036 and anterior flange 1042. Posterior piston segment 1038, in 
continuity with intermediate piston segment 1032, extends posteriorly 
through opening 1030 of chamber 1008. 
Trigger member or means 1070 is mounted in side wall 1041 of piston chamber 
1008, inferiorly. As better seen in FIG. 3, trigger member 1070 is 
composed of stub 1073 fastened to wall 1041 via fastener 1071 and 
resilient latch 1072, grossly U shaped, mounted within window 1077 of side 
wall 1041 of piston chamber 1008. Latch 1072 has arrest tooth 1074 engaged 
within annular recess 1076 of intermediate piston member 1038, releasably 
locking piston 1016 and latch locking tooth 1075. 
Within posterior chamber 1014, posterior to intermediate segment piston 
1032 and protruding inferiorly from side wall 104 1, is arrest pin 1078. 
Interface member chamber 1010 of general cylindrical shape is delimited 
laterally by side wall 1052, open anteriorly via opening 1048 and open 
posteriorly via centrally located opening 105 1, within posterior wall 
1050. Spring 1046 is also contained in interface member chamber 1010, 
posteriorly to interface member 1044, seating on posterior wall 1050, 
being interposed between side wall 1052 and inner wall 1057 of interface 
member chamber 1010. 
Interface or intermediate member 1044 of general cylindrical hollow shape, 
slideably mounted within intermediate member chamber 1010, has at front 
end 1060 formed with passageway 1059 for arrest rod 1102. The posterior 
segment of intermediate member 1044 being positioned, with the device in 
position of rest, between side wall 1052 and inner walls 1057 of interface 
member chamber 1010. Front end 1060 of intermediate member 1044 engages 
catheter hub 1009 by hook 1082 releasably engaging catheter hub flange 
1084. Interface member 1044 is also formed with annular recess 1066 for 
ball member 1036 as it will be explained below. 
Arrest unit 1100 of general cylindrical shape is at the front and superior 
end of housing 1002. Arrest unit 1100 is isoaxial and distal to interface 
member chamber 1010 being in continuity with it by side wall 1052 
prolonging forward up to connect with arrest unit 1110 as best seen in 
FIG. 1. 
As best seen in FIG. 4, arrest unit 1100 is formed with cylindrical seating 
1104 where push-cylinder 1106 is slideably mounted, annular recess 1102 
where centripetal resilient arrest ring 1110 is mounted and central axial 
passageway 1112 for arrest rod 1114. Push-cylinder 1106 is with the device 
in position of rest, resting on front end 1060 of interface member 1044. 
Push-cylinder 1106 can however also be constructed as integral part of 
interface member 1044 in continuity with front end 1060 of interface 
member 1044. Centripetal resilient arrest ring 1110 is not allowed to 
tightens on arrest rod 1114 by circular arrest 1108. As best seen in FIG. 
2, arrest rod 1114 is composed of shaft 1111, proximal end 11. 13 and 
distal end 1115 to which arrest plate 1117 is firmly attached at angle. 
Arrest rod 1114 in position of rest is slideably concentrically mounted 
from back to front within hollow space or cavity 1121 of interface member 
1044, passageway 1059 of front end 1060 of intermediate member 1044 and 
passageway 1112 of arrest unit 1110. Rod 1114 presents multiple 
indentations 1119 for arrest ring 1110. Arrest plate 1117 has opening 1120 
large enough to permit the passage of needle 1004, catheter 1006 and 
catheter hub 1009 as it will be explained in the description of the 
operation. 
Interface member chamber 1010 and piston chamber 1008 are separated for the 
whole length by devider wall 1091. A window 1099 is formed in the devider 
wall 1091 to house ball member 1036. As shown in FIG. 2 with the device in 
position of rest, prior to use ball member 1036 is shown engaged in window 
1099 of divider wall 1091, seating inferiorly on side wall of piston 1016 
and, superiorly, locking intermediate member 1044 by engaging 
correspondent annular recess 1066 of interface member 1044. 
Hollow needle 1004 has a tip 1003 and protrudes from needle hub 1005 which 
has been previously described. 
Catheter 1006 with hub 1009 is slideably mounted respectively over needle 
1004 and needle hub 1005. 
DESCRIPTION OF THE OPERATION 
FIGS. 5 to 8 show the device in use. The body cavity represented in this 
case is the trachea for description purpose only. The device can be used 
for any body cavity or anatomical hollow structure having walls of the 
human body naturally present or pathologically formed, either air or gas 
or fluid filled. As seen in FIG. 5, in use, the operator, pushes forward 
piston 1016 by acting upon posterior piston segment 1038. Trigger latch 
1072 will be displaced outwardly by posterior flange 1079 of intermediate 
piston segment 1038 unlocking so piston 1016. Locking latch- tooth 1075 
will unreleasably lock latch 1075 outwardly. With piston 1016 maintained 
in a fully advanced position by the operator hand acting upon posterior 
piston segment 1038, the operator penetrates skin 1092 of pretracheal 
space or body cavity wall 1093 with needle tip 1003. Grip on posterior 
piston segment or plunger 1038 is then released by the operator when 
needle tip 1003 is well under skin 1092. Posterior displacement of piston 
1016 urged posteriorly by spring 1040 will create a vacuum in front of 
piston head 1022. However due to the sealing qualifies of the skin and 
subcutaneous tissue of pretracheal tracheal space 1093, piston 1016 will 
be posteriorly displaced by only a fraction as shown in FIG. 5. Needle 
1004 with its catheter 1006 concentric to it, is then advanced by the 
operator through the pretracheal space 1093. Arrest rod 1114 will be 
displaced posteriorly during this maneuver as arrest plate 1117 will be 
impeded to advance by coming in contact with the neck of the patient. 
As best seen in FIG. 6, as soon as needle tip 1003 will penetrate tracheal 
space or body cavity 1095 by penetrating through cricothyroid membrane 
1096, backflow of the content of body cavity 1095, air, gas or fluid, is 
accelerated through hollow needle 1004 into vacuum chamber 1012 by the 
presence of the vacuum. Vacuum pressure in front of piston 1018 will 
vanish or will be reduced allowing so posterior displacement of piston 
1016 up to arrest tooth 1078. As seen in FIG. 5, ball 1036, forwardly 
-urged by spring or resilient means 1046 via annular recess 1066, due to 
its eccentric position with its equator below the upper edge of window 
1099, no longer retained in window 1099 of devider wall 091 will fall in 
wide annular recess 1034 of piston 1016 releasing so interface member 1044 
from it locked starting position, free so to be urged forward by the 
action of spring 1046. Interface member 1044 advancement by spring or 
resilient means 1046 will lock arrest rod 1114 and cause also advancement 
of catheter 1005 by interface member front end 1060 acting upon flange 
1084 of catheter hub 1009. 
As seen in FIG. 6 and 7, advancement of front end 1060 of interface member 
1044 will displace forward push-cylinder 1116 which in turn will displace 
forward arrest ring 1110, dislodging it from its resting position i.e. 
seating on arrest tooth 1118. Arrest ring 1110 no longer retained in the 
expanded position by arrest tooth 1118 will be able to tightens around the 
nearest of the indentations 1119 of arrest rod 1114 causing so its 
locking. Needle 1004 will be no longer advanceable into the tracheal space 
due to plate 1117 resting in locked position over skin 1092 of the 
pretracheal space 1093. Advancement of catheter 1006 will be carried out 
by front end 1060 of intermediate member 1044 for the whole length of 
needle base 1011. Front end 1060 will then loose engagement with catheter 
hub 1009 due to the fact that catheter hub 1009 will rest on needle nozzle 
1013 of smaller diameter. Further advancement of catheter 1006 can be 
accomplished manually of as best seen in FIG. 9 by the operator until 
optimal positioning is reached within the tracheal lumen or body cavity 
1095. 
FIG. 9 shows an all similar version of the device described in FIGS. 1 to 8 
except that the catheter is advanced manually by the operator. The only 
structural difference is that the front end 1060' of interface 1044 is not 
engaging catheter hub 1009. The device is operated exactly as the 
previously described device, however advancement of interface member 1044 
will only cause arrest of arrest rod 1114. Catheter 1006 will have to be 
advanced by hands by the operator grabbing it by the hub 1009. 
FIG. 10 shows an all similar version of the device described in FIGS. 1 to 
8 except that in this version there is no catheter concentric to the 
needle or cannula and the cannula or needle is detacheable from the 
device. In this version of the device, cannula or needle 1004 is connected 
with its hub 1005 in a detacheable air tight fashion to housing 1002 via 
flange 1200 of hub 1005 screwed on thread 1097 of nozzle 1099 of housing 
1002. The presence of sealing ring 1098 further insures the air tightness. 
The device is operated as the previously described device without a 
catheter. In this case once a body cavity is penetrated by the needle tip 
1003 and arresting means or unit 1100 is actuate& the operator can detach 
needle 1004 from housing 1002 by unscrewing needle 1004 from housing 1002, 
leaving needle 1004 front portion within the body cavity for whatever use, 
such as fluid aspiration or drainage. Needle hub 1005, if necessary, will 
be ready for any connection.