chapter  3
22 Pages

- Introduction to Needles and Cannulae

Needle Gauges and Sizes .........................................................................................44 Gauge Size ..........................................................................................................44 French Catheter Size ........................................................................................... 45

Metric and English ................................................................................................... 45 Working with Hypodermic Tube ............................................................................. 45 Common Hypodermic Tubing Materials ................................................................. 47 R&D Needle Grinding ............................................................................................. 47 Simple Compound Needle Grinding Fixture ...........................................................48 Suture Needles ......................................................................................................... 49 Basic Types of Suture Needle Tips .......................................................................... 52

Conventional Cutting .......................................................................................... 52 Reverse Cutting .................................................................................................. 52 Side Cutting ........................................................................................................ 52 Taper Point .......................................................................................................... 52 Blunt Point .......................................................................................................... 52

Suture Attachment Methods .................................................................................... 52 Swaging Sutures to Needles ............................................................................... 52 Drill ..................................................................................................................... 53 Channel ............................................................................................................... 53 Nonswaged, Closed Eye, French Eye, Slit, Spring ............................................ 53

Suture Sizes ............................................................................................................. 53 Suture Types ............................................................................................................ 53

Natural Absorbable .............................................................................................54 Natural Nonabsorbable .......................................................................................54 Synthetic Absorbable ..........................................................................................54 Synthetic Nonabsorbable .................................................................................... 55

Trocars and Dilators ................................................................................................ 55 Trocars ................................................................................................................ 55 Blunt Dilators ...................................................................................................... 55 Plastic Sharps and Trocars for Disposables ........................................................ 55

Glossary of Needles and Related Terms .................................................................. 57 Resources ................................................................................................................. 61

Reference: Phlebotomy ....................................................................................... 61

One of the most common materials used in medical devices is small-diameter (hypodermic) stainless steel tubing. One of the most common medical devices is the hypodermic needle. Another is the suturing needle, and others include trocars and cannulae. Needles and cannulae have been used in medicine since the dawn of recorded history. The ancient Egyptians used metal tubes to gain access to the bladder and other structures. Needles are used for a wide variety of functions, such as injection, suturing, biopsy, gaining access to a surgical space, delivery of radio frequency (RF) energy for tissue ablation, delivery of electrical impulses for evoked potential tests, holding thermocouples for temperature measurement, guiding other devices such as guidewires and catheters, and numerous other applications.