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We investigated the flow rates of 25-G and 27-G spinal needles, of 90-mm and 120-mm lengths, from Vygon, BD, B. Braun and Pajunk; the needles had either a Luer connector, or a Surety® or UniVia® non-Luer connector. We used a bench-top model of entering the spinal space, pressurised to 35 cmH2 O to simulate cerebrospinal fluid pressure in the sitting position. We examined the time to first appearance of simulated cerebrospinal fluid in the needle hub, as well as the amount of fluid collected over 120 s after the needle was introduced. The mean (SD) times to first appearance of fluid in the needle hub of Luer spinal needles varied from 0.36 (0.22) s for the 25-G 90-mm BD to 3.14 (0.72) s for the 27-G 120-mm B. Braun, and in the non-Luer spinal needles from 0.22 (0.17) s for the 25-G 90-mm B. Braun to 2.99 (0.71) s for the 27-G 120-mm Pajunk. There was a significant difference in the time to first appearance of fluid in the needle hub between Luer and non-Luer needles of the same type for seven of 14 comparisons made, of which four showed slower appearance of fluid in the non-Luer version. In some of these cases, the time to appearance of fluid was nearly twice as long with the non-Luer counterpart. The mean (SD) weight of fluid collected in 120 s using the Luer spinal needles varied from 0.21 (0.05) g for the 27-G 120-mm Pajunk to 1.21 (0.18) g for the 25-G 90-mm Vygon, and using the non-Luer spinal needles from 0.25 (0.05) g for the 27-G 120-mm Pajunk to 1.55 (0.05) g for the 25-G 90-mm B. Braun. All of the needle types showed a greater weight of fluid collected using the non-Luer compared with the Luer version, with six of the 14 needle types showing a significant difference. Significant variations in flow were also seen between the same needle type from different manufacturers. We conclude that changing from Luer to non-Luer versions of spinal needles does not merely change the hub design and connection, but may introduce important differences in function.

Summary We performed an evaluation of non-Luer spinal devices supplied by four manufacturers or suppliers: Polymedic; Pajunk; Sarstedt; and Smiths. For each supplier, 100 evaluations were performed using a 25-G 90-mm spinal needle, 3-ml syringe, 5-ml syringe and filter needle; for comparison, 100 evaluations were performed with our standard Luer equipment. The non-Luer devices were associated with more qualitative problems compared with the Luer devices, for example, poor feel of dural puncture (9–32% vs 10%, respectively), poor observation of cerebrospinal fluid in the hub (3–27% vs 0%), and connection problem of the syringe to the spinal needle (7–33% vs 0%). There was also more frequent failure to achieve the spinal injection due to equipment-related causes (4–7% vs 0%, respectively). Median (IQR [range]) numeric satisfaction scores for the spinal needles were: Luer 10 (9–10 [7–10]); Polymedic 7 (4–8 [0–10]; Pajunk 7 (5–8 [0–10]); Sarstedt 7 (6–8 [0–10]); and Smiths 9 (7–10 [0–10]) (p < 0.0001). Satisfaction scores for all spinal equipment were: Luer 10 (9–10 [5–10]); Polymedic 8 (6–8 [0–10]); Pajunk 7 (5–7 [1–9]); Sarstedt 8 (6–8 [0–10]); and Smiths 8 (8–9 [2–10]) (p < 0.0001). Between 21% and 75% of non-Luer evaluations were rated with satisfaction worse than the usual Luer needle compared with 0–10% rated better, depending on the needle type. Between 22% and 76% of non-Luer evaluations were rated with satisfaction worse than the usual Luer equipment compared with 0–14% rated better. Specific concerns included poor feel of tissue planes and observation of cerebrospinal fluid (Polymedic), difficulty with connection of the syringe to the spinal needle and trocar removal (Pajunk), poor feel of tissue planes and needle flexibility (Sarstedt) and difficulty with connection of the syringe to the spinal needle (Smiths). We could not demonstrate a short-term learning curve for the new devices. Decisions on purchasing and implementation of the new non-Luer equipment will have to acknowledge that clinicians may have greater technical problems and reduced satisfaction compared with the current equipment.

The history of the design of spinal needle tips is discussed, from the first needles used by J. Leonard Corning in 1885 to innovative, modern needle designs that continue to appear on the market. The shape of the needle tip started as a cutting bevel and developed into the atraumatic tip and the pencil-point tip in current common use. Innovative designs such as the stylet-tipped needle and the directional needle are described, as well as the needles used for continuous spinal anaesthesia.

This study was performed to determine how the use of an introducer affects the extent to which a needle deflects during a spinal or combined spinal-epidural injection. A polystyrene block was used to simulate the paraspinal area of the back. A line was drawn perpendicular to the edge of the block to use as a guide and to measure the deflection. The use of an introducer needle decreased the deflection in all the bevelled needles (p < 0.001). Depending on the direction of both the bevels, the deflection decreased as the introducer bevel was changed from the same direction, to right-angles to bevel direction and then to a direction opposite to that of the spinal needle (p < 0.05). Deflection was decreased when a thick introducer was used (p < 0.001). The use of an introducer increased the deflection of the pencil-point needle only in the deflection direction of the introducer (p < 0.001). The 18-gauge Tuohy needle with a "backhole" deflected more than the corresponding needle without a backhole (p < 0.001), and the spinal needle inserted through the Tuohy needle with a backhole deflected more (p = 0.002). Besides the tip type and gauge, the deflection of a spinal needle depends upon the use of introducer, its gauge and bevel direction. The deflection of a Tuohy needle depends upon its design, gauge and the presence of a backhole.

BACKGROUND: No studies have evaluated the relationship between duration of time sitting and spinal needle type on the maximal spread of local anaesthetics. The few trials available have studied the influence of time spent sitting on the spread of anaesthesia without standardising spinal needle types, and have not found any effect. METHODS: In this randomised, blinded study, 60 patients scheduled for elective orthopaedic surgery of the lower limbs were divided into 4 groups. With the patient sitting erect, 15 mg hyperbaric bupivacaine were injected in a standard manner through a 24G Sprotte or a 27G Whitacre needle and patients were placed supine after 1 min (24G/1 group and 27G/1 group) or 4 min (24G/4 group and 27G/4 group). RESULTS: Time to achieve maximum block height after injection was similar in all groups. Block height levels were significantly lower at all time points for the 24G/4 group. Maximum block heights were Th4 in the 24G/1, 27G/1 and 27G/4 groups, and Th6 in the 24G/4 group (P

Objective.—To evaluate atraumatic spinal needle use among US neurologists. Background.—Postdural puncture headache following lumbar puncture may be dramatically reduced through the use of atraumatic pencil-point spinal needles. It was hypothesized that atraumatic spinal needles are rarely used by members of specialties outside of anesthesiology. To determine the extent to which atraumatic spinal needles are currently being used for lumbar puncture in the United States, American neurologists (one group of physicians who regularly perform lumbar punctures) were surveyed. Methods.—A questionnaire was mailed to all 7798 members of the American Academy of Neurology listed in the membership directory. The questionnaire included items pertaining to age, practice setting, knowledge of pencil-point (atraumatic) spinal needles, and lumbar puncture practices. Results.—Only a fraction (2%) of the neurologists surveyed routinely use atraumatic spinal needles. Almost half of the responding neurologists reported having no knowledge of pencil-point spinal needles. Among those who did have knowledge of these new spinal needles, the most common reasons given for not using them were nonavailability and expense. Conclusions.—Atraumatic spinal needles for lumbar puncture have been shown to dramatically decrease the risk of postdural puncture headache. Although the use of these needles is standard practice among anesthesiologists, they have not been adopted by other medical specialties. This may lead to unnecessary morbidity among patients undergoing lumbar puncture.

We examined the flow pattern produced when liquid dye was actively injected into a fluid medium at various flows through five different commonly used spinal needles. At all flows, the Whitacre-type needles produced a directional stream exiting at an angle from the longitudinal axis. At intermediate rates the stream developed tracks which disappeared at faster rates. The Quincke needle always produced an undeviated stream of dye and did not form tracks at any flow rate. When a perspex plate (representing the spinal cord) was interposed in front of the needle, the dispersion of dye was always unidirectional from the Whitacre needle and bidirectional from the Quincke needle. The dye adhered to the surface of the plate as a concentrated film at slow rates and at faster rates it dispersed turbulently for both types of needle.

Background: The tips of modern thin Quincke-type spinal needles may be easily damaged by bone contact during the puncture. The purpose of this study was to find out the frequency of tip deformation in routine clinical work and the appearance of the dural perforations made by such damaged needles. Methods: Two hundred and ninety-five Quincke-type needles (22G-29G) used in routine spinal anaesthesia were inspected by light microscopy. Scanning electron micrographs were taken of some of the damaged tips and of experimental dural perforations made by these. Results: Four per cent of the needle tips were clearly bent or hooked and 11% were slightly bent. When an introducer needle was used (19 cases), one needle was clearly bent and one slightly bent. A puncture with a bone contact was associated with clear tip damage in 7%; a puncture without bone contact resulted in an undamaged or slightly bent needle tip in 99% of the cases. The numbers of bent tips among the various sizes were: 22G-2/21, 25G-13/40, 27G-28/231, 29G-1/3. In scanning electron microscopy (SEM) images of four clearly bent needle tips the deviation of the tip was between 10 μm and 20 μm. In SEM of eleven dural perforations, the holes made by needles with clearly bent tips were almost closed and three of them exhibited an “open tin can” appearance. None of the dural perforations was badly torn. Conclusions: We verified that the tips of modern thin spinal needles are vulnerable to damage due to contact with bone. However, the holes made in dura by needles with bent tips do not appear to be excessively torn.

Reports have indicated that there are less postoperative complaints after the use of pencil pointed spinal needles. We compared a 24G Sprotte needle with a 27G Quincke needle in a randomised study of 200 healthy patients (49% females), aged 15-46 years. Four patients (2%) reported postdural puncture headache, three with the 24G Sprotte needle and one with the 27G Quincke needle. Thirteen patients (7%) suffered with nonspecific headache, with no significant difference between the two groups. Of the 57 (29%) who reported backpain, a significantly higher proportion had received spinal anaesthesia with the Sprotte needle (OR = 2.06). There was a significantly higher incidence of insufficient blocks after dural puncture with the Sprotte needle. Ease of needle insertion and number of puncture attempts was the same for both needle types.

Objective To assess fetlock joint contamination with tissue debris and hair after arthrocentesis. Study Design Experimental. Animals Fetlock joint tissues (n = 10 horses). Methods Soft tissue flaps including the joint capsule were dissected from the dorsal fetlock joints of 7 anesthetized horses leaving an intact proximal base. Needles inserted through the tissue flaps were flushed into tissue cell culture plates and examined for debris. Studies were repeated on excised fetlock tissue preparations after being stored for 5 days. Variables included gauge and type of needle, insertion of spinal needles with and without a stylet, angle of insertion, length of hair, and ante- and postmortem needle insertion. Tissue fragments collected from 3 horses were cultured for bacteria. Results Compared to 20 g disposable needles inserted perpendicularly through unclipped skin, the odds ratios (ORs) for hair contamination were significantly greater for 20 g spinal needles without a stylet, and significantly less for 22 g spinal needles inserted with a stylet and for angled insertion of disposable needles. Tissue contamination OR was significantly less for 20 g spinal needles inserted without a stylet, angled insertion, and clipped hair. Bacteria were isolated from 2.6% of tissue fragments. Conclusions Angled needle insertion reduces joint contamination with tissue and hair. Spinal needles should be inserted with a stylet in place and 22 g spinal needles are preferable to 20 g spinal needles. Joints may be contaminated with bacteria after routine surgical preparation of skin.

Spinal needles with a pencil-point tip and those of a finer gauge are known to be associated with a lower incidence of postdural puncture headache. This study set out to determine if fine pencil-point needles were acceptably easy to use in routine clinical practice. Two hundred and twelve women undergoing elective Caesarean section were randomly allocated to receive a subarachnoid block using either a 25 G or 27 G Whitacre needle. Factors determining ease of needle use, adequacy of block, incidence of postdural puncture headache, backache and neurological sequelae were assessed. Successful intrathecal injection was achieved in all patients in the 25 G group. Using the 27 G needle, the anaesthetist failed to reach the subarachnoid space in eight patients of which seven subsequently had a successful intrathecal injection with a larger needle. These failures were attributed to excessive needle flexibility which was the only significant difference in ease of use between the 25 G and 27 G needles. In the 25 G group, there was one severe postdural puncture headache which required an epidural blood patch and three mild headaches which resolved spontaneously. There were no postdural puncture headaches in the 27 G group. We conclude that the final choice of needle is a compromise between the ease of use and lower failure rate of the 25 G needle and the, as yet unproven, possibility of a lower incidence of postdural puncture headache with the 27 G needle.

This study investigated whether the tips of spinal needles are damaged during the process of spinal anaesthesia by impact on bone, by repeated attempts at performing the block or by the use of an introducer. Used spinal needles from five different hospitals were carefully resheathed after use and a questionnaire completed. The needles were examined under a light microscope with the observer unaware of the questionnaire data. Two hundred and twenty-two needles were examined, of which 36 were damaged. Five unused control needles of each type were also examined and all were found to be undamaged. There was no significant difference between the damaged and undamaged used needles with respect to impacts on bone or the number of attempts. Pajunk 24G Sprotte needles were significantly less likely to sustain damage when the integral introducer was used as compared to an alternative introducer.

The important features which determine the ease of use of spinal needles include rapid detection of cerebrospinal fluid, minimal delay before injection and low resistance to injection of local anaesthetic. We investigated these three parameters among the following 11 spinal needles: Becton-Dickinson 22 G, 25 G and 27 G Whitacre, 25 G and 27 G Quincke; B. Braun Spinocan 22 G, 25 G and 26 G Quincke; Vygon 25 G Whitacre, Portex 26 G Pencil Point and the 24 G Sprotte. Three needles of each type were tested using an artificial cerebrospinal fluid model maintained at body temperature and at two hydrostatic pressures of 12 and 50 cm of water. The Becton Dickinson 27 G Whitacre has an immediate detection time at both pressure heights, a reasonably short 'ready to inject' time and relatively low resistance to injection, which, together with a reported low rate of postdural puncture headache, would indicate that it is the most appropriate for spinal anaesthesia. The 25 G Whitacre types would be the next most suitable to use.

The effect of different size (25-, 27- and 29-gauge) Quincke-type spinal needles on the incidence of insertion difficulties and failure rates was investigated in a randomised, prospective study with 300 patients. The needle size was randomised but the insertion procedure was standardised. The time to achieve dural puncture was significantly longer with the 29-gauge spinal needle compared with the larger bore needles and was due to the greater flexibility of the thin needle. However, the difference was less than 1 min and cannot be considered clinically significant. There were no significant differences between groups in the number of insertion attempts or failures and the same sensory level of analgesia was reached with all the needle sizes studied. Postoperatively, no postdural puncture headaches occurred in the 29-gauge spinal needle group, whilst in the 25- and 27-gauge needle groups, the postdural puncture headache rates were 7.4% and 2.1% respectively. The incidence of backache was similar in all study groups. We conclude that dural puncture with a 29-gauge spinal needle is clinically as easy as with larger bore needles and its use is indicated in patients who have a high risk of postdural puncture headache.

A new needle, 120 mm long and 26 gauge in diameter, has been introduced for subarachnoid anaesthesia. The resistance to flow through the needle was measured using a pressure monitor infusion pump and compared with the resistance to flow through a 90-mm 26-gauge needle; there was a threefold increase in resistance in the 120-mm needle compared to the 90-mm needle, which could not be explained by the difference in length alone and must reflect a decrease in the internal diameter of the long needle. This results in difficulty in identifying the subarachnoid space by backflow of cerebrospinal fluid.

Lumbar puncture is an important diagnostic procedure in emergency medicine. Data have been published showing improved success rate with ultrasound assistance and the ability of emergency medicine physicians to recognize sonographic lumbar spinous anatomy. However, with educational models and the push for improved patient safety, procedural skills should be practiced on phantoms rather than the “see one, do one, teach one” of the past. There are no currently available phantoms for ultrasound-assisted lumbar puncture training. We have produced a phantom that can be used to train physicians on ultrasound-assisted lumbar puncture with respect to both imaging and procedural competency. A plastic fluid-filled bladder was immersed in gelled opacified mineral oil, a safe and easily used tissue mimic that obscures direct visualization of structures. Spinous anatomy is replicated with the use of wooden struts supporting wooden disks that mimic lumbar spinous processes. The spine analog was mounted over the plastic bladder and surrounded with gelled mineral oil. The phantom produces images similar to human lumbar anatomy. The phantom allows insertion of spinal needles into the “interspinous spaces” with inability to pass the needle outside of those locations. Fluid collection and repeated punctures can be performed on the phantom. Appearance and performance of the phantom were evaluated by physicians with expertise in ultrasound-assisted lumbar puncture. The only limitation is that external appearance is not realistic. This model performs well, is made from readily available materials, and can be used to train physicians in ultrasound-assisted lumbar puncture.

The postero-anterior lumbar spine X rays of 163 patients undergoing investigation for back pain were reviewed and the spinal level marking the intersection of a line joining the iliac crests was determined. This point coincided with the L4 spinous process or the L4-5 interspace in 78.6% of patients but was as high as the L3-4 interspace in 3.7% of cases. Reliance on this landmark might lead to more cranial placement of epidural or spinal needles than was intended and this may increase the risk of spinal cord damage.

Leakage of artificial cerebrospinal fluid through human dura was measured in vitro after puncture by spinal needles. Fluid loss tailed off in all cases and ceased within 5 minutes in 10% of punctures made with a 22-gauge needle, 28% made with a 26-gauge and 65% made with a 29-gauge needle (p less than 0.05). The fluid loss was not reduced by alignment of the level of the needle parallel to the longitudinal direction of the fibres. Whitacre point needles of 22 gauge produced lower fluid loss than a 22-gauge Quincke point needle inserted across the fibres (p less than 0.05). Leakage rate was related to needle size, but not related to the alignment of a Quincke point. Little or no leakage occurred with 29-gauge needles.

Summary: Use of the intraosseous (i.o.) route as an alternative venous access for drug administration has increased. This study examined the efficacy of i.o. lorazepam (LZP) in suppressing pentylenetetrazol (PTZ)-induced seizure activity in pigs. Domestic swine (13–20 kg) were prepared for recordings of arterial blood pressure, EEG, and electrocortical activity. Seizure activity was induced by PTZ (100 mg/kg i.v.). Sixty seconds after onset of seizure activity, animals either received no drug (control) or LZP (1.0 mg/kg) administered i.v. or i.o. via an 18- or 13-gauge spinal needle inserted in the right proximal tibia. Both i.o. and i.v. LZP significantly suppressed the duration of seizure activity (DSA) (s/min interval) within 1 min following drug administration: DSA control, 46.2 ± 3.6; i.v. LZP, 25.0 ± 5.1; i.o. (18-gauge) LZP, 27.6 ± 6.0; i.o. (13-gauge) LZP, 24.0 ± 2.4. Seizure activity was essentially abolished at 1 min following LZP infusion. In addition, both i.v. and i.o. LZP did not have significant effects on the basal heart rate and mean arterial blood pressure. The data demonstrate that in swine (1) the i.o. route is an effective alternative venous access for LZP administration, and (2) the size of spinal needles does not affect the antiepileptic efficacy of i.o. infusion of LZP. RESUME La voie intra-osseuse (i.o.) comme alternative a la voie intraveineuse pour administration de medicaments est de plus en plus souvent utilisee. Ce travail etudie efficacite du Lorazepam i.o. dans la suppression de crises induites chez le pore par le pentylene tetrazol (PTZ). Des pores domestiques (poids 13–20 kg) ont ete prepares pour enregistrement de la pression arterielle, de EEG et de activiteelectrique corticale. Une activiteepileptique a ete induite par administration intraveineuse (i.v.) de PTZ (100 mg/kg). 60 s apres le debut de activite critique, les animaux ont recu soit aucun medicament (groupe controle), soit du Lorazepam (1.0 mg/kg) administre i.v. ou i.o. au moyen une aiguille a ponction lombaire de calibre 18 ou 13 inseree dans la partie proximate du tibia droit. Le Lorazepam i.o. et i.v. a significativement reduit la duree des crises pendant la premiere minute suivant administration du medicament: controle: 46.2 ± 3.6; Lorazepam IV, 25.0 5.1; Lorazepam i.o. (calibre 18), 27.6 ± 6.0; Lorazepam i.o. (calibre 13) 24.0 ± 2.4. activite critique a ete pratiquement abolie dans la minute qui a suivi injection de Lorazepam. De plus, le Lorazepam i.v. ou i.o. n'a pas modifie de facon significative le rythme cardiaque de base et la pression arterielle moyenne. Ces donnees demontrent que chez le pore: (1) la voie administration i.o. est une alternative efficace a acces veineux pour administration de Lorazepam; (2) le calibre de aiguille a ponction lombaire ne modifie pas efficacite antiepileptique une injection de Lorazepam. RESUMEN La utilizacion de la via intraosea (i.o.) como altemativa a la via venosa para la administracion de medicaciones se ha incrementado. En este estudio se examina la eficacia del lorazepan i.o. para suprimir la actividad epileptica inducida por el pentilentetrazol (PTZ) en cerdos. Se utilizaron cerdos domesticos (13–20 kg) preparados para registro de presion arterial, EEG y actividad electro-cortical. La actividad epileptica fue inducida con PTZ intravenoso (i.v.) (100 mg/kg). Sesenta segundos despues del comienzo de la actividad epileptica los animates no recibieron nioguna medicacion (controles) o se administero lorazepan (1.0 mg/kg), i.v. o i.d. utilizando una agujas de puncion lumbar de los numeros 18 o 13 insertadas en la porcion proximal de la tibia derecha. Tanto el lorazepan i.o. como el i.v. suprimieron significativamente la duracion de los ataques (SD) en el primer minuto que siguio a la administracion de la droga: SD control, 46.2 ± 3.6; lorazepan i.v., 25.0 ± 5.1; lorazepan i.o., (aguja no. 18) 27.6 ± 6.0; lorazepan (aguja no. 13), 24.0 ± 2.4. La actividad epileptica fue esencialmente eliminada en el minuto que siguio a la infusion de lorazepan. Ademas no se observaron efectos significativos en el ritmo cardiaco basal o la presion arterial media durante las vias i.v. o i.o. Esta information demuestra que, en el cerdo, la via i.o. es una buena alternativa a la utilizacion de la via venosa para la administracion del lorazepan y que los tamaos de las agujas no alteran su eficacia antiepileptica. ZUSAMMENFASSUNG Der intraossare Zugang als Alternative zum intravenosen zur Medikamentengabe wird zunehmend benutzt. Diese Studie un-tersucht die Wirksamkeit von i.o.-Lorazepam-Gabe zur Unter-druckung Pentylen-tetrazol (PTZ)–induzierter Anfallsaktivitat beim Schwein. Hausschweine (13 bis 20 kg) wurden fur arterielle Blutdruckmessung, EEG und ECG vorbereitet. Die Anfallsaktivitat wurde durch PTZ (100 mg/kg i.v.) ausgelost. 60 Sekunden nach Beginn der epileptischen Aktivitat erhielten die Tiere entweder Lorazepam (1,0 mg/kg) i.v. oder i.o. uber eine 18er oder 13er Spinalkanule in der rechten proximalen Tibia–die Kontrolltiere erhielten kein Medikament. Sowohl i.o. –als i.v. -Gabe von Lorazepam unterdruckte signifikant Anfallsdauer (SD, Sek./ Min.-Intervall) innerhalb von 1 Sek. nach Medikamentengabe: SD 46.2 ± 3.6; i.v. 25.0 ± 5.1, i.o. (18er) 27.6 ± 6.0, i.o. (13er) 24.0 ± 2.4. Die Anfallsaktivitat war in der Regel 1 Minute nach Lorazepam-Infusion beseitigt. Weiterhin hatte weder i.v. noch i.o. Lorazepam signifikante Nebenwirkungen auf das Herz-Kreislaufsystem. Die Ergebnisse zeigen, das beim Schwein (a) der i.o.-Zugang eine wirkungsvolle Alternative zum i.v.- (b) Zugang fur die Gabe von Lorazepam darstellt und die Kanulengrose die antiepileptische Wirkung von i.o.-Infusion nicht beeinflust.