INTRODUCTION / BACKGROUND

This case study is designed for dental hygiene students, dental students, and medical students preparing to begin clinical rotations. The students are expected to have a basic knowledge of anatomy and physiology, pathophysiology, and biology. The case is particularly helpful prior to the beginning of clinical rotations so that engineering controls can be developed and reviewed.

Objectives

By working through this case, the student will be able to:

1. state proper post-exposure protocol
2. state the relative risks of HIV and Hepatitis transmission in a dental setting
3. develop an acceptable method of needle recapping
4. gain an appreciation for importance of confidentiality of medical records

CLASSROOM MANAGEMENT

Numbers of students vary depending on the institution's enrollment. Typically, this case is best managed in groups of 20 to 30 students. The case is divided into three distinct sections, which are intended to be given to the students in a progressive disclosure format. Allowing approximately 15 minutes of discussion for each section permits the case to be managed in a one-hour class.

Student Preparation

Prior to the use of this case, students need to review their institution's engineering controls for prevention of exposures, their institution's post-exposure protocol, and relative risks of HIV and Hepatitis transmission.

BLOCKS OF ANALYSIS

This case is divided into three parts. In the first part, "The Incident," some background information is given regarding the characters. Medical students, dental students, and dental hygiene students are all able to identify with the clinical situations. A would-be dental student is stuck by a contaminated needle during the routine administration of anesthetic in the first scenario. This incident allows the discussion to go in many different directions: (1) how it could have been prevented, (2) what follow-up steps are necessary, or (3) what rights the source (Ralph) has as well as the person stuck by the contaminated needle (Jennifer). In order to best direct the discussion so that all pertinent points are discussed, questions relating to how the needlestick could have been prevented are asked first.

1. Proper engineering controls to prevent needlesticks due to improper recapping techniques

Avoidance of percutaneous exposure to bloodborne pathogens through improper needle recapping is a relatively simple procedure provided proper engineering controls are in place. Using the lecture method to instruct a student on a "scoop" method of recapping a needle may result in inadequate retention of the material. One suggestion to have this material retained better is to have the students devise their own method of recapping a needle, stressing the importance of never bringing the operator's hands together, as this method often results in a needle stick. By providing each student with a syringe and needle cap or even a ball point pen and cap, the instructor can allow the students to work individually or in groups until an acceptable recapping method has been developed.

2. Proper injection techniques, i.e., the significance of injecting a solution containing epinephrine into an artery or vein

A review of aspiration techniques can be done here to ensure each student's understanding of the importance of injection technique. Aspirating syringes should be used so that, after the student locates the injection site, they would then aspirate. Positive aspiration, signified by the presence of blood in the anesthetic cartridge, indicates that the tip of the needle was located in an artery or vein. Injecting a solution containing epinephrine, which is a vasoconstrictor, into the bloodstream can cause a variety of problems including tachycardia.

If aspiration is positive, the student should be instructed to reposition the needle and aspirate again. This procedure is done until the anesthetic cartridge is free from blood.

3. Relative risks of transmission of Hepatitis C and HIV

Hepatitis C

Hepatitis C Virus (HCV) infection is the most common chronic bloodborne infection in the United States. Chronic liver disease is the tenth leading cause of death among adults in the United States, and accounts for approximately 25,000 deaths annually, or approximately 1% of all deaths. Population studies indicate that 40% of chronic liver disease is HCV-related. HCV is transmitted primarily through large or repeated direct percutaneous exposures to blood. The average incidence of anti-HCV seroconversion after unintentional needle sticks or sharps exposures from an HCV-positive source is 1.8% (range 0% - 7%), with one study reporting that transmission occurred only from hollow-bore needles (such as in Needles and Pins) compared with other sharps.

HIV

Prospective studies of health care workers (HCWs) have estimated that the average risk for HIV transmission after a percutaneous exposure to HIV-infected blood is approximately 0.3% (range 0.2% - 0.5%) and after a mucous membrane exposure is 0.09% (range 0.006% - 0.5%). Epidemiologic and laboratory studies suggest that several factors may affect the risk for HIV transmission after an occupational exposure. One retrospective case-control study of a health care worker with a percutaneous exposure to HIV found that the risk for HIV transmission was increased with exposure to a larger quantity of blood from the source patient as indicated by a) a device visibly contaminated with the patient's blood, b) a procedure that involved a needle placed directly in a vein or artery, or c) a deep injury. It was estimated that the risk for HIV transmission from exposures that involve a larger volume of blood, particularly when the source patient's viral load is probably high, exceeds the average risk of 0.3%. In Part I of "Needles and Pins," it is stated that there was positive aspiration during the administration of the anesthetic. This indicates that the needle tip was in a vein or artery, therefore increasing the risk of HIV transmission.

In the second part of the case, "Jennifer's Dilemma," Jennifer is worried about the risks associated with the needlestick. The objective of this portion of the case is to ensure that the students understand post-exposure protocol. Presentation in this format, rather than a lecture, will hopefully allow the students to better conceptualize the scenario. The major issue of Part II is proper post-exposure protocol. Current guidelines are: (1) removal of the glove, (2) washing the exposed site with soap, and (3) squeezing the site to extrude blood. While the retired Navy dentist is correct, the risk of transmission of disease is negligible, proper post-exposure protocol must be followed in all cases.

In the last part of the case, "Ralph's Response," ethical issues of the case are introduced. The major objectives of this portion of the case include: (1) confidentiality of patient records, (2) post-exposure follow-up, and (3) patient rights.

Ralph was within his rights to refuse to have his blood drawn. Assuming he never acquiesced, Jennifer would have to have blood drawn at baseline and continue to have blood drawn at 3-, 6-, and 12-month intervals. It is critical that Jennifer has her blood drawn at baseline to determine her pre-exposure status. If she did not and was later found to have an infectious disease, it would be impossible to be certain when the disease originated. His sexual orientation is of little significance in this case. If Ralph were to be HIV+, his viral load would have to be considerably high to substantially increase the risk of disease transmission.

REFERENCES

1. Dufour MC. Chronic liver disease and cirrhosis. In Everhart JE, ed. Digestive diseases in the United States:epidemiology and impact. US Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Washington, DC: US Government Printing Office, 1994; NIH publication no. 94-1447, 615-45.

2. Alter MJ. Occupational exposure to hepatitis C virus: a dilemma. Infect Control Hosp Epidemiol 1994;15:742-4.

3. Lanphear BP, Linnemann CC Jr, Cannon CG, DeRonde MM, Pendy L, Kerley LM. Hepatitis C virus infection in healthcare workers: risk of exposure and infection. Infect Control Hosp Epidemiol 1994;15:745-50.

4. Puro V, Petrosillo N, Ippolito G. Italian study Group on Occupational Risk of HIV and Other Bloodborne Infections. Risk of hepatitis C seroconversion after occupational exposures in healthcare workers. Am J Infect Control 1995;23:273-7.

5. Mitsui T, Iwano K, Masuko K, et al. Hepatitis C virus infection in medical personnel after needlestick accident. Hepatology 1992;16:1109-14.

6. Bell DM. Occupational risk of human immunodeficiency virus infection in healthcare workers: an overview. Am J Med 1997:102(suppl 5B):9-15.

7. Ippoloto G, Puro V, DeCarli G, the Italian Study Group on Occupational Risk of HIV Infection. The risk of occupational human immunodefieciency virus infection in health-care workers. Arch Intern Med 1993;153:1451-8.

8. Cardo DM, Culver DH, Ciesielski CA, et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. N Engl J Med 1997;337:1485-90.

Acknowledgements: This case was developed as part of a National Science Foundation-sponsored Case Studies in Science Workshop (NSF Award #9752799) held at the State University of New York at Buffalo on June 7-11, 1999.