Retractable centesis needle
A retractable centesis needle comprises a hollow, sharp tipped outer cannula extending from a housing. The outer cannula is generally tube-like and open at both ends to form a channel into a cavity in the housing. A blunt tipped inner cannula is disposed within the channel and capable of sliding away from the housing to an extended state and toward the housing to a refracted state. The inner cannula is biased toward the extended state by a first spring disposed in the housing. A second spring also disposed in the housing acts in the same direction as the first spring when the inner cannula is in a fully retracted state. However, the second spring does not bias the inner cannula in any direction when the inner cannula is in a fully extended state.
1. A retractable centesis needle comprising:
a housing having a cavity;
a hollow outer cannula extending distally from the housing, said outer cannula being open at both ends and defining a channel therethrough;
an inner cannula slidably disposed within the channel, wherein said inner cannula is adapted to slide between a fully extended state and a fully retracted state;
a first biasing member disposed in the housing cavity, said first biasing member configured to apply force to the inner cannula and biasing the inner cannula distally;
a second biasing member disposed in the housing cavity, said second biasing member configured to variably apply force to the inner cannula wherein the second biasing member distally biases the inner cannula when in the fully retracted state, and wherein the second biasing member does not bias the inner cannula when in the fully extended state.
2. The retractable centesis needle according to claim 1 , wherein the distal end of the inner cannula terminates in a blunt tip and the distal end of the outer cannula terminates in a sharp tip, said sharp tip having an outer edge, wherein the outer edge is rounded or chamfered.
3. The retractable centesis needle according to claim 1 , further comprising an indicator disposed within the housing cavity, and a hub associated with the inner cannula, said hub adapted to removably cover at least a portion of the indicator.
4. The retractable centesis needle according to claim 3 , wherein the indicator is at least partially covered when the distal end of the inner cannula extends beyond the distal end of the outer cannula, and wherein the indicator is completely uncovered when the distal end of the inner cannula is retracted within the distal end of the outer cannula.
5. The retractable centesis needle according to claim 4 , wherein the indicator is completely uncovered when the distal end of the inner cannula is aligned with the distal end of the outer cannula.
6. The retractable centesis needle according to claim 3 , wherein the indicator and the hub are colored in contrasting colors.
7. The retractable centesis needle according to claim 3 , the indicator further including a conical rim configured to accept a distal edge of the hub, and the hub further comprising a head portion and a tail portion, wherein the head portion is proximal to the tail portion, and wherein the second spring is shorter than the first spring.
8. The retractable centesis needle according to claim 7 , wherein the hub has a tail portion adapted to contact the first spring and a head portion adapted to contact the second spring.
9. The retractable centesis needle according to claim 3 , further comprising a sleeve disposed within the cavity, said sleeve having a window, wherein at least a portion of the indicator is viewable through the window.
10. The retractable centesis needle according to claim 9 , wherein the window includes a magnifying lens.
11. The retractable centesis needle according to claim 9 , further comprising a cap attachable to the proximal end of the housing and a one-way valve disposed within said cap, wherein said valve is a duckbill type valve.
12. The retractable centesis needle according to claim 11 , wherein the cap includes a luer-type connection at the proximal end.
13. The retractable centesis needle according to claim 1 , wherein the first and second biasing members are compression springs.
14. The retractable centesis needle according to claim 1 , wherein the housing is transparent.
15. The retractable centesis needle according to claim 4 , wherein the housing further includes a window, wherein at least a portion of the indicator is viewable through the window.
16. The retractable centesis needle according to claim 9 , the indicator further including a flange wherein the distal end of the sleeve is adapted to secure the flange against the housing.
17. The retractable centesis needle according to claim 1 , wherein the distal end of the housing includes a luer-type connection.
18. The retractable centesis needle according to claim 1 , wherein an indicating state is defined by alignment of the distal end of the outer cannula with the distal end of the inner cannula, the indicating state occurring when the first biasing member is compressed by a force between 0.15 lbs and 0.35 lbs.
19. A retractable centesis needle comprising:
a housing having a cavity;
an indicator disposed in one end of the cavity;
a hollow outer cannula extending from the housing, said outer cannula being open at both ends and defining a channel therethrough;
an inner cannula slidably disposed within the channel, said inner cannula having a hub adapted to cover the indicator;
a first biasing member disposed in the housing cavity, said first biasing member configured to bias the hub in a first direction toward the indicator;
a second biasing member disposed in the housing cavity, said second biasing member configured to bias the inner cannula in the first direction when the indicator is not covered by the hub.
20. A drainage system for centesis procedures comprising:
a catheter having a distal end and a proximal end;
a stopcock coupled to the proximal end of the catheter;
a check valve coupled to the stopcock; and
a retractable centesis needle comprising: a housing having a cavity; a hollow outer cannula extending distally from the housing, said outer cannula being open at both ends and defining a channel therethrough; an inner cannula slidably disposed within the channel, wherein said inner cannula is adapted to slide between a fully extended state and a fully retracted state; a first biasing member disposed in the housing cavity, said first biasing member configured to apply force to the inner cannula and biasing the inner cannula distally; a second biasing member disposed in the housing cavity, said second biasing member configured to variably apply force to the inner cannula wherein the second biasing member distally biases the inner cannula when in the fully retracted state, and wherein the second biasing member does not bias the inner cannula when in the fully extended state, said retractable centesis needle adapted to be inserted through the check valve, the stopcock, and the catheter.