1992, The British Journal of Radiology, 65, 264-265
Technical notes
A fine needle aspiration technique using high negative pressure By * J . C. Rhymer, FRCS, D. W. McRobbie, BSc, MSc and J . E. Boultbee, FRCR Department of Diagnostic Radiology, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK (Received 24 May 1991, accepted 23 July 1991) Keywords: Aspiration
Ultrasound-guided aspiration for diagnostic or therapeutic purposes plays an important role in the management of thoracic, abdominal or pelvic fluid collections. The use of a fine needle is safe (Dewbury, 1990) having the advantages of minimal tissue trauma and minimal patient discomfort. The disadvantage of a small needle of 22 gauge is that its bore limits the rate of aspiration, which is significant in dealing with large or viscous collections. The use of a hand held syringe can be tiring for the operator and needle movement or displacement can occur during prolonged aspirations. We describe a simple method of overcoming some of these disadvantages.
pressure. The three way tap allows the vacuum to be created in the syringe and is essential in the aspiration of pleural collections. The use of the plastic needle sheath means that no extra cost is incurred. The operator is not "tired" by continuous aspiration and is free to perform some other task whilst the syringe is filling. These factors, we believe, mitigate against needle tip displacement and increased tissue trauma. Using "fish scales", we have calculated that some 9 6 x l 0 3 N n ~ 2 pressure is achieved in evacuating the tube, just less than 1 atm pressure. This pressure is compatible with values obtained using auto FNAC
Method The assembly consists of: 1. A 22 gauge spinal needle with a Quincke type point and a Luer Lok hub (Bector Dickinson & Co.). 2. A "Connecta" three way stopcock with a 10 cm extension tube and a Luer Lok fitting (Vigga-Spectramed). 3. A 50 cc or other suitably-sized syringe. The fine needle is advanced into the collection using an aseptic technique after local anaesthesia. The placement of the needle is confirmed by aspirating fluid using a standard syringe, having withdrawn the stylet. The extension tube is used to connect the needle to the syringe. The three way tap at the syringe end of the tube is closed to the syringe, and the syringe plunger fully withdrawn and wedged in this position by inserting the plastic sheath, which protects the fine needle before use between the flange of the syringe plunger and the flange on the syringe barrel (Fig. 1). The three way tap is then opened and the collection aspirated. Discussion We have used this technique to aspirate serous and purulent collections. The use of the extension tube guards-'against needle displacement during movement of the syringe. It also allows intentional movement, repositioning the needle as the collection changes shape and size, whilst maintaining a continuous negative •Present address: Department of Diagnostic Radiology, Queen Mary's Hospital, Roehampton, London SW15. 264
Figure 1. The British Journal of Radiology, March 1992
Technical notes
samplers as reported by Kreula (1990). For a nonviscous fluid such as water, a 20 ml syringe will fill in about 45 s using this assembly. The calculation does not take into account turbulence or friction, but agrees closely with experiments performed using the apparatus. TM rTn- A• • i c • a •i i The filling time is longer for viscous fluids such as pus.
Vol. 65, No. 771
References DEWBURY, K. C, 1990. Ultrasound in Techniques in Diagnostic Imaging, ed. by G. H. Whitehouse & B. Worthington (Blackwell Scientific Publications, Oxford) p. 434. KREULA J ' . " 1990- S , u c t l o n , a n A cel1 y i e I d / " R™, n e e c " e aspiration Kbiopsy. Journal of Interventwnal Radiology, 5, 131-135
265
Technical notes
A fine needle aspiration technique using high negative pressure By * J . C. Rhymer, FRCS, D. W. McRobbie, BSc, MSc and J . E. Boultbee, FRCR Department of Diagnostic Radiology, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK (Received 24 May 1991, accepted 23 July 1991) Keywords: Aspiration
Ultrasound-guided aspiration for diagnostic or therapeutic purposes plays an important role in the management of thoracic, abdominal or pelvic fluid collections. The use of a fine needle is safe (Dewbury, 1990) having the advantages of minimal tissue trauma and minimal patient discomfort. The disadvantage of a small needle of 22 gauge is that its bore limits the rate of aspiration, which is significant in dealing with large or viscous collections. The use of a hand held syringe can be tiring for the operator and needle movement or displacement can occur during prolonged aspirations. We describe a simple method of overcoming some of these disadvantages.
pressure. The three way tap allows the vacuum to be created in the syringe and is essential in the aspiration of pleural collections. The use of the plastic needle sheath means that no extra cost is incurred. The operator is not "tired" by continuous aspiration and is free to perform some other task whilst the syringe is filling. These factors, we believe, mitigate against needle tip displacement and increased tissue trauma. Using "fish scales", we have calculated that some 9 6 x l 0 3 N n ~ 2 pressure is achieved in evacuating the tube, just less than 1 atm pressure. This pressure is compatible with values obtained using auto FNAC
Method The assembly consists of: 1. A 22 gauge spinal needle with a Quincke type point and a Luer Lok hub (Bector Dickinson & Co.). 2. A "Connecta" three way stopcock with a 10 cm extension tube and a Luer Lok fitting (Vigga-Spectramed). 3. A 50 cc or other suitably-sized syringe. The fine needle is advanced into the collection using an aseptic technique after local anaesthesia. The placement of the needle is confirmed by aspirating fluid using a standard syringe, having withdrawn the stylet. The extension tube is used to connect the needle to the syringe. The three way tap at the syringe end of the tube is closed to the syringe, and the syringe plunger fully withdrawn and wedged in this position by inserting the plastic sheath, which protects the fine needle before use between the flange of the syringe plunger and the flange on the syringe barrel (Fig. 1). The three way tap is then opened and the collection aspirated. Discussion We have used this technique to aspirate serous and purulent collections. The use of the extension tube guards-'against needle displacement during movement of the syringe. It also allows intentional movement, repositioning the needle as the collection changes shape and size, whilst maintaining a continuous negative •Present address: Department of Diagnostic Radiology, Queen Mary's Hospital, Roehampton, London SW15. 264
Figure 1. The British Journal of Radiology, March 1992
Technical notes
samplers as reported by Kreula (1990). For a nonviscous fluid such as water, a 20 ml syringe will fill in about 45 s using this assembly. The calculation does not take into account turbulence or friction, but agrees closely with experiments performed using the apparatus. TM rTn- A• • i c • a •i i The filling time is longer for viscous fluids such as pus.
Vol. 65, No. 771
References DEWBURY, K. C, 1990. Ultrasound in Techniques in Diagnostic Imaging, ed. by G. H. Whitehouse & B. Worthington (Blackwell Scientific Publications, Oxford) p. 434. KREULA J ' . " 1990- S , u c t l o n , a n A cel1 y i e I d / " R™, n e e c " e aspiration Kbiopsy. Journal of Interventwnal Radiology, 5, 131-135
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