Self Filling Injection Device and Safe Device Holder

1. Introduction

In surgery rooms, procedures involve anesthesia and tumescence applications which are applied over a large area and require repetitive actions for a longer period of time. The process consists of preparation of a solution, handling of the various medication cups and the devices used to deliver the solution. In hair transplant applications, anesthesia is given to the donor and recipient sites. Both sites are large and require delivery of considerable anesthetic and tumescent solutions. For example, Dr. Cole’s technique is to infiltrate the donor area with 25 to 75 cc of Normal Saline. The typical anesthetic IV bag solution used by the authors is 100 cc Saline solution 0.9% with added 25 cc of Lidocaine, 0.5 cc of epinephrine, 2.5 cc Sodium Bicarbonate and 0.25 cc Kenalog. Similarly, typical tumescent IV bag solution is a 100 cc of saline solution 0.9% in an IV bag with added 5 cc of Lidocaine 2%, 0.5 cc of epinephrine 1/1000 and 0.25 cc Kenalog.

The mostly used devices like syringes or similar ones use hypodermic needles of different gages. After preparing the solution, the procedure involves the aspiration of the solution from a medication cup, delivery of the solution in to the subject and then placing the device on the working bench for the rest of the time [2]. The repeated aspiration from a cup is a two handed operation. In addition, a sharp injury and spilling the solution in the working area may take place due to the routine nature of the repeated delivery and aspiration activity. The use of such devices cause fatigue to the hand and the movement back and from the medication cup to the patient is time consuming. In addition, the movement in the room between the medication cup and the patient should be limited to minimize risk of sharp injury. There is also more and more tendency to use disposable medical devices [1] to reduce the risk of improper sterilization of tools. To address the above issues, a device should fulfill at least the following requirements.

The most commonly used devices are Syringes to mix solutions, to aspirate the solution and deliver to the subject. Use of Syringes does not solve any of the above issues. There were some self filling Injection devices like a Unimatic Syringe which address most of the above requirements. The original ones were sold at a medical conference around 1997. They are no longer available for human application and the quality/workmanship has deteriorated and can not resist the autoclave environment. Nowadays, they are marketed specially for veterinary applications. Other devices in use include 10 ml control syringes that are filled once refilled after all the fluid is delivered out. These Syringes may also be used with 3-way stopcocks or even with dual check valve. This arrangement needs some skill and does not automatically refill and does not solve the fatigue problem on the hand. It does not solve the accidental sharp injury issue either. Therefore, a Self Filling Injection Device and the Safe Injection Device Holder are developed to address most of the problems mentioned above.

2. Description of the Device 2.1 Self Filling Injection Device

A Self Filling Injection Device is a hand operated device that enables a user to utilize one hand to administer an injection while the fluid is supplied from a bag or a bottle placed on an IV-pole in a continuous manner. The Self Filling Injection Device utilizes a typically available disposable syringe and converts it to a Self Filling Injection Device. In addition, compression and expansion movements of a spring-loaded guide and return mechanism allow repetitive automatic filling of liquid from a reservoir like a bag or a bottle and repetitive delivery of the same to the subject.

Figure 1 Self Filling Injection Device main sub-assemblies.

A Self Filling Injection Device comprises a main unit, a syringe assembly, and a dual check valve as shown in Fig 1. The main unit comprises a front handle, a back handle, a spring assembly, a guide pin and a lock. The main components of this device are shown in Fig 2. The spring box assembly comprises a female type spring guide, a male type spring guide, a spring, and a set screw or a blind flange. The spring enclosed between the two guides and locked in position with a set screw allows compression and extension of the assembly in response to a manually exerted force. The male type guide of the spring assembly is connected to back handle by threading.

Figure 2 Self Filling Injection Device assembly Components.

The guide pin is coupled to the back handle by screwing into back handle and is made to freely slide through the guide hole in the front handle. A dose adjust sleeve is assembled to the front end of the guide pin by using a set screw. The spring assembly specifically the female type guide is fixed to the front handle by threading. This assembly and a dual check valve comprise the main unit of the device. When ready to use, remove the front handle by removing the sleeve on the guide pin and by unscrewing the spring guide box. In this condition, the back handle is assembled to the guide pin and the spring box. A plunger flange of a syringe assembly like a BD syringe is placed in the recess disposed in the back handle and locked in position with the lock plate. The front handle is then inserted on to the syringe barrel and the guide pin. The female type guide of the spring box is fixed to the front handle by threading. The flange of the syringe barrel is inserted in the slot provided on the front handle and rotated until stopped by a pin in the slot. Then the dose adjust sleeve is inserted on to the guide pin and locked against the guide pin with a set screw. As shown in Figure x, a dual checkvalve assembly is coupled to an end of syringe with a luer lock mechanism. A dual checkvalve may comprise springs and an inlet ball valve or port and an outlet ball valve or port. The balls in the valves may be loaded with springs such that the balls open and close the ports depending on whether such a valve is subjected to a suction or an injection process. The inlet valve may be connected to a hose extending to a fluid bag or bottle and the outlet valve may be connected to a hypodermic needle. The fluid bag or bottle is connected to the inlet valve by means of a hose and may be placed on an IV pole as shown in Fig. 4.

This device may be held such that the forefinger may be inserted into a gap on the front handle between the syringe and the spring box, while one or more other fingers may be placed under spring box. In an initial state, the spring is in an extended position. A user may initiate a forward motion, such as by pushing back handle towards the front handle from a starting position. Such a motion results in compression of the spring and as a result the syringe plunger moves forward. During such forward motion, the outlet valve of the dual checkvalve opens while the inlet valve closes under the spring forces acting on the balls on the two sides. If the user releases the pressure applied to the back handle, the spring will push the back handle away from front handle. As a result, the handle may likewise pull with it the male type spring guide, the syringe plunger, and the guide pin to the initial position. During this motion, the outlet valve closes and inlet valve opens under the spring forces acting on the balls on the two sides. In this case fluid will be drawn or sucked into syringe barrel from a fluid bag or bottle by a suction force created in syringe barrel. If back handle is pushed towards front handle again, the outlet valve opens and the inlet valve closes under the spring forces acting on the balls on the two sides. Thus the fluid content in the syringe barrel may be discharged through hypodermic needle that may be injected into a subject or patient.

The dual checkvalve may be made up of a corrosion-resistant stainless steel to ensure a repetitive sterilization (autoclaving). It may also be made of a thermoplastic material that may not be re-sterilized or may be disposed off with the Syringe. The future plan is to make the whole device out of a thermoplastic material and make the entire unit disposable and affordable. This device also allows adjustment of the dose volume in the syringe barrel. A dose adjust sleeve is coupled to the guide pin by using a set screw. One face of the dose the adjust sleeve is used as a stopper against the front handle. The position of the dose adjust sleeve may determine the relative position of syringe plunger which in turn determines a dose in the syringe. The position of the dose adjust sleeve may be changed by loosening the set screw, moving the dose adjust sleeve to a new position and re-tightening the set screw. As a result of the new position, the syringe plunger may be moved back and forth to define a new dose in the syringe barrel and may be determined by looking at a scale provided on a standard syringe barrel that may be aligned with the tip of the rubber boot assembled on the syringe plunger.

The Self Filling Injection Device assembled with a Syringe, a hypodermic needle and a hose from the fluid bag shall be placed on a Safe Injection Device Holder

Safe Injection Device Holder (Safe Injection Device Holder)

In surgery rooms, extensively exposed sharps have been the cause of accidental injuries with the risk of contamination and transmission of diseases. The needle attached to the Injection Device need to be placed such that it is safe from contamination and the sharp tip should not be accessed as much as possible by people working around. The Needle-stick Safety and Prevention Act (the Act) (Pub. L. 106-430) was signed into law on November 6, 2000. Because occupational exposure to blood-borne pathogens from accidental sharps injuries in healthcare and other occupational settings continues to be a serious problem, Congress modified the OSHA's Bloodborne Pathogens Standard (29 CFR 1910.1030) to set forth in greater detail (and make more specific) OSHA's requirement for employers to identify, evaluate, and implement safer medical devices [3].

Figure 3 Safe Injection Device Holder mounted on an IV pole.

The Safe Injection Device Holder shown in Fig. 3 addresses this problem. It is used to mount the Self Filling Injection Device in a safe place when it is not in use. The Safe Injection Device holder may be made of a geometry that allows an easy placing and removal of the Injection Device. The holder may be mounted and secured on an IV pole with the help of a pole mount ring using set screws. The holder can be easily removed for cleaning and autoclaving. To place the Injection Device, the same is brought to a position where it may be slid down quickly and left in the guides. The Back handle of the Injection Device rests on an upper ledge and the front handle in the middle portion as shown in Fig. 4. The hose extending out of the valve inlet port can freely extend out towards the top part of the IV pole hanger to be connected to the bags or bottles. The needle may be contained in all sides except one and can not be reached easily. To remove, hold the front handle and pull upwards and away from the holder. The Injection Device may be reached and grabbed with one hand without using assistance from the second hand. There are two Safe Injection Device Holders on one IV pole. For example, two fluid bags, one for a tumescent solution and one for the anesthetic solution may be connected to two Self Filling Injection Devices. In addition to this, the entire assembly on the IV pole can be moved close to the patient during use and moved away from the surgery area when not in use. This helps to maximize use of space and also to reduce the movement in the room with sharps in the hand.

Figure 4 Self Filling Injection Device placed in a Safe Injection Device Holder mounted on an IV pole

Summary

The Self Filling Injection Device and the Safe Injection Device Holder discussed above were designed with the various surgery room requirements in mind. These two devices are developed such that they are set up easily and quickly, they reduce hand fatigue, are safe during and when not in use, save space and time and require almost no maintenance. The future plan is to design and manufacture the Self Filling Injection Device from plastic materials and make it a one time use device. This is mainly to deal with the sterilization problems which may be issues in some clinics.

REFERENCES

1. Since July 2007, new regulations in the UK mean that clinics can no longer re-sterilize their own instruments. Ref: Hair Transplant Forum International, Volume 19, Number 3, pp 109

2. About anesthesia and tumescence solutions, refer to article Ref: http://www.ishrs.org/member/forum-html/2005/6/art_7_15_6.php

3. http://www.osha.gov/needlesticks/needlefaq.html