Strength of commonly used spinal needles: the ability to deform and resist deformation

We investigated the strength of commonly used spinal needles in relation to the amount of deformation, and registered forces during standardised testing. We investigated differences between manufacturers for the same length and gauge of Luer and non‐Luer needles, and examined the effect of the internal stylet in terms of needle strength. A specialised rig was designed to perform the testing in both the horizontal and axial plane, reflecting common industrial tests and clinical use. Needles from four commonly used manufacturers were used (Vygon, Becton Dickinson, B Braun, and Pajunk). Needles of 25 G and 27 G were tested in 90‐mm and 120‐mm lengths. We found significant differences in terms of the size of final deformation and ‘toughness’/resistance to deformation between needles of different brands. There were also significant differences between horizontal tests conducted as an industry standard and our own axial test. This may have bearing on clinical use in terms of the incidence of bending and breakage. The presence of the internal stylet resulted in significantly greater toughness in many needles, but had little effect on the degree of deformation. Comparison of Luer and non‐Luer needles of the same brand and size showed few significant differences in strength. This result is reassuring, given the imminent change from Luer to non‐Luer needles that is to occur in the UK.     

A clinical evaluation of four non‐Luer spinal needle and syringe systems

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.     

An evaluation of non‐Luer safety connectors for neuraxial procedures

We evaluated seven non‐Luer spinal needles in a two‐part study. In part 1, we measured the time to see and collect simulated cerebrospinal fluid. In part 2, clinicians scored needle quality using a standardised questionnaire. The mean (SD) times to see cerebrospinal fluid varied in the lateral position from 4.2 (0.3) s (Vygon) to 25.2 (1.5) s (Sarstedt), and in the sitting position from 1.7 (0.2) s (BBraun) to 6.6 (0.3) s (Sarstedt). The time to collect cerebrospinal fluid varied from 43 (2.5) s (Vygon) to 139 (9.6) s (Pajunk) and from 19 (0.4) s (BBraun) to 34 (1.7) s (Pajunk), for the lateral and sitting positions, respectively. Median (IQR [range]) satisfaction scores in 205 needle function assessments were as follows: Sarstedt 9.0 (8.0–9.3 [5.0–10.0]); BD 8.0 (7.0–9.5 [3.0–10.0]); Pajunk 9.0 (8.0–9.8 [5.0–10.0]); Neurax 8.0 (7.0–9.0 [2.0–9.0]); Smiths 8.0 (7.0–9.0 [4.0–10.0]); Vygon 8.0 (7.5–9.0 [5.0–10.0]); and BBraun 9.0 (9.0–10.0 [7.0–10.0]). The difference in satisfaction scores between the BBraun and Neurax was significant (p < 0.01). A number of recurrent problems were found during the evaluation. The variation in time to collect cerebrospinal fluid samples may have implications for non‐anaesthetic practice. This evaluation provides a baseline to assist others in commencing their procurement process.     

Comparison of 25 G and 29 G Quincke spinal needles in paediatric day case surgery. A prospective randomized study of the puncture characteristics, success rate and postoperative complaints

A comparison of a 25 G with a 29 G Quincke needle was performed in paediatric day case surgery. Sixty healthy children aged 1 year to 13 years were randomly allocated to have spinal anaesthesia with either 25 G or 29 G Quincke needle without an introducer needle. There was a failure rate of 10% with the 29 G spinal needle compared with 0% with the 25 G needle. The time needed to perform dural puncture was shorter using 25 G than 29 G needle, 22 (±31)(SD) vs 59 (±63) s. The time taken for cerebrospinal fluid to appear at the needle hub was also longer, 4 (±3) vs 8 (±5) s. The number of puncture attempts was similar, 1.2 (±0.6) vs 1.4 (±0.8), with 25 G and 29 G needle. Low back pain, 5 vs1, and nonpositional headache, 2 vs 4, after 25 G and 29 G needles, respectively, were the most frequent postoperative complaints. Mild postdural puncture headache occurred in one eight year old male patient in the 25 G group. In conclusion, lumbar puncture without introducer needle was possible with both needles. The puncture characteristics favoured the 25 G needle. A shorter needle could partly alleviate the difficulties with the 29 G needle.     

Postural post-dural puncture headache. A prospective randomised study and a meta-analysis comparing two different 0.40 mm O.D. (27 g) spinal needles

BACKGROUND: To compare the incidence of postural post-dural puncture headache (PPDPH) after spinal anaesthesia using two different 0.40 mm O.D. (27 g) spinal needles: pencil-point needle and Quincke needle. In addition, a meta-analysis of studies comparing small bore spinal needles with regard to development of PPDPH was performed. METHODS: Clinical study: A prospective randomised double-blind study was set up to investigate PPDPH after using 0.40 mm pencil-point (Pencan, B. Braun) or Quincke (Spinocan, B. Braun) spinal needle. Postoperatively on day 5 to 7 a telephone interview was conducted in order to reveal postoperative complications such as headache and backache. PPDPH was considered present when the headache was new to the patient, and demonstrated posture dependence. Meta-analysis: Electronic database search and manual search of relevant literature were performed in order to find randomised control trials comparing equal sized (outer diameter, O.D.) spinal needles with different bevel shape. Only studies with a proper method and not merely presented as an abstract were included in addition to the present clinical study. RESULTS: Out of 313 patients randomised, 301 were completely followed up, 153 in the pencil-point group and 148 in the Quincke group. The two groups were comparable regarding surgical procedures and demographic data. Of 15 patients suffering from PPDPH, 12 were found in the Quincke group, and 3 in the pencil-point group. The difference was 6.1% (95% CI from 1.2 to 12.5%). The meta-analysis of 1131 patients gave a relative risk of developing PPDPH of 0.38 (95% CI from 0.19 to 0.75) in the pencil-point group compared to the Quincke group. CONCLUSION: A pencil-point-shaped spinal needle will significantly reduce PPDPH compared with Quincke-type spinal needles, also when small bore needles (0.40 mm O.D.) are used.     

Deformed spinal needle tips and associated dural perforations examined by scanning electron microscopy

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.     

Spinal needle design and size affect the incidence of postdural puncture headache in children

Background: In adults, pencil point spinal needles are known to be less traumatic and hence to be superior compared with cutting point needles in respect of postpuncture complications. In children, only a few trials have evaluated the difference in the incidence of postdural puncture headache (PDPH) using spinal needles with different tip designs. The aim of this study was to evaluate the success rate and the incidence of PDPH and backache following spinal anesthesia (SA) with the two types of needles currently in use for children. Methods: This is a retrospective study of prospectively collected data. The success rate and postpuncture complications of 26G cutting point (Atraucan^®) spinal needle were compared with 27G pencil point (Pencan^®) spinal needle in 414 children aged 2–17 years undergoing surgery with SA. Results: Both needles had similar first‐attempt success rates: 87% in the cutting point group and 91% in the pencil point group (P = 0.16). Pencil point needles caused less PDPH compared to cutting point needles; 0.4% vs 4.5%, respectively (P = 0.005). Both needles caused similar backache (P = 0.08). No severe neurologic symptom was reported for both needles. Conclusion: The data suggest that 27G pencil point spinal needles lead to less PDPH compared to 26G cutting point spinal needles in children.     

Assessment of a new disposable introducer for spinal needles

The compatibility between spinal needles and their introducers varies between manufacturers and can significantly influence the usable length of the spinal needle available resulting in failure to locate CSF in larger patients. The usable length of 90‐mm pencil point spinal needles from four manufacturers ranged from 68 to 79 mm when the needle was used in combination with its introducer. A new purpose‐built introducer needle is described which, when used with a 25 g or finer spinal needle, maximises the usable length of the needle. Using this new introducer the usable needle length of a 90‐mm Whitacre needle was increased by a further 7 to 86 mm resulting in only a 4 mm loss of total needle length. The new introducer was well received by users.     

Post-dural puncture headache in young patients. A comparative study between the use of 0.52 mm (25-gauge) and 0.33 mm (29-gauge) spinal needles

In a prospective study of 80 patients under 40 years of age, given spinal anaesthesia through either a 0.52 mm (25-gauge) needle or a 0.33 mm (29-gauge) needle, the incidence of post-dural puncture headache and backache was compared. There were no headaches in the 0.33 mm needle group, while in the 0.52 mm needle group an incidence of 25% was found. The incidence of backache was the same in both groups. The technique of performing spinal anaesthesia was evaluated and concluded to be slightly more difficult with a 0.33 mm needle, as estimated by the number of redirections of the needle needed to obtain cerebrospinal fluid. There were no differences between the two needles with respect to obtaining adequate spinal anaesthesia and spread of blockade.     

An objective assessment of nerve stimulators used for peripheral nerve blockade*

Nerve stimulation is considered by many to be the current 'gold standard' for locating peripheral nerves. Thirteen nerve stimulators were subjected to a battery of tests performed by two independent observers under standardised conditions using a digital oscilloscope, a calibrated resistance and a novel scoring system. Individual scores were assigned for the signal waveform, current intensity, impulse duration, maximum load output and functionality of each nerve stimulator; the maximum score achievable was 20. A score of > or = 15/20 was achieved by six nerve stimulators: Stimuplex HNS 12 (B Braun); MultiStim Vario (Pajunk); Plexival (Medival, Vygon); MultiStim Sensor (Pajunk); Plexygon (Aryon, Vygon); Stimuplex HNS 11 (B Braun). Seven nerve stimulators scored < 15/20. Anaesthetists should be aware of the limitations of the nerve stimulator being used. Standardisation of features is desirable when manufacturing nerve stimulators.     

Comparison of 27-gauge (0.41-mm) Whitacre and Quincke spinal needles with respect to post-dural puncture headache and non-dural puncture headache

BACKGROUND: The incidence of headache after spinal anaesthesia has varied greatly between studies. We compared the incidence of postoperative headache in general and postdural puncture headache (PDPH) when using 27-gauge (G) (outer diameter 0.41 mm) Quincke and Whitacre spinal needles in ambulatory surgery performed under spinal anaesthesia. Methods: In a prospective, randomized study, 676 ASA physical status I-II day-case outpatients were given a spinal anaesthetic through either a 27-G (0.41 mm) Quincke or a 27-G (0.41 mm) Whitacre spinal needle. The incidence of any type of postoperative headache was assessed and the type of headache defined using a standardized questionnaire including PDPH criteria. The severity of the headache was defined using a 100-mm visual analogue scale. Results: For the final analysis, 529 patients were available (259 patients in the Quincke group and 270 patients in the Whitacre group). The overall incidence of postoperative headache was 20.0%, but the incidence of true PDPH was very low (1.51%). The incidence of PDPH in the Quincke group was 2.70%, while in the Whitacre group it was only 0.37% (P < 0.05). The overall incidence of non-dural puncture headache was 18.5% and did not differ between the study groups. Conclusions: True PDPH seldom occurs when a 27-G (0.41 mm) spinal needle is used, although postoperatively a non-specific headache is common. Using the 27-G (0.41 mm) Whitacre spinal needle further reduced the incidence of PDPH. Thus, we recommend routine use of the 27-G (0.41 mm) Whitacre spinal needle when performing spinal anaesthesia.     

Comparison of 26-gauge Atraucan® and 25-gauge Whitacre needles: insertion characteristics and complications

Ninety-six women undergoing post-partum tubal ligation under spinal anaesthesia were studied to compare 26G Atraucan® with 25G Whitacre spinal needles for ease of insertion, number of attempts at needle insertion, cerebrospinal fluid (CSF) flow characteristics through the needles, quality of subsequent analgesia, and incidence of perioperative complications. A higher rale of successful durai puncture at the first attempt (40/50 vs 27/46, P < 0.05) and faster (mean ± SD, 11.5 ± 2.2 vs 13.5 ± 2.4, P < 0.001) CSF flow through the needle was achieved with the Atraucan® than with the Whitacre needle. The incidence of failed spinal (4% vs 5%) and post-dural puncture headache (PDPH) (4% vs 4.3%) was similar with both needles, but more patients experienced paraesthesiae during needle insertion with the Whitacre than with the Atraucan® needle (15% vs 2%, P < 0.05). We conclude that the use of the 26G Atraucan® needle is associated with a higher rate of successful identification of the subarachnoid space at the first attempt, faster CSF backflow, and fewer paraesthesia when compared with the 25G Whitacre needle.     

Is the pencil point spinal needle a better choice in younger patients? A comparison of 24G Sprotte with 27 G Quincke needles in an unselected group of general surgical patients below 46 years of age

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 heActache, three with the 24G Sprotte needle and one with the 27G Quincke needle. Thirteen patients (7%) suffered with nonspecific heActache, with no significant difference betwen 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.     

Evaluation of a spinal needle locking device for use with the combined spinal epidural technique

Success of the 'needle-through-needle' technique for combined spinal epidural analgesia requires the immobilisation of the spinal needle during intrathecal injection. A device that achieves this was evaluated in 200 labouring women, randomly allocated to receive a combined spinal epidural using the CSEcure(R) (SIMS Portex, UK) locking needle or a conventional, non-locking technique. Data collection included the incidence of dural click as the spinal needle penetrated the dura mater, presence of cerebrospinal fluid in the spinal needle hub and the number of technical failures with the spinal component. Successful dural punctures with the spinal needle were similar for locking and non-locking needles (99.0 vs. 98.0%; p = 0.55), despite a small but significant reduction in dural click with the locking needle compared with the non-locking technique (97. 0 vs. 84.7%; p < 0.01). Although not statistically significant, there was a higher number of technical failures, mainly due to spinal needle movement, in the non-locking group (9.1 vs. 3.1%; p = 0.08). The locking needle device may be a useful alternative to conventional methods for combined spinal epidural analgesia.     

Posture-related distribution of hyperbaric bupivacaine in cerebro-spinal fluid is influenced by spinal needle characteristics

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<0.0001). CONCLUSION: In a standard spinal anaesthesia procedure, when different lengths of time spent sitting are compared, spinal needle characteristics influence the maximum spread of hyperbaric bupivacaine. However, within the limits of our study, a two-segment difference in block height is too small to consider using spinal needles as valuable tools to control block height during spinal anaesthesia in our daily practice.     

Postspinal headache. A comparison of the 24G Sprotte syringe and a 29G Quincke needle]

PATIENTS AND METHODS. A randomised study was performed to compare the frequency of postdural puncture headache in 56 patients who underwent spinal anaesthesia for extra-corporeal shockwave lithotripsy using either a Sprotte 24 G (n = 28) or Vygon 29 G or Quincke type needle (n = 28). Frequency of headache was recorded in a similar group of 28 patients who received general anaesthesia. RESULTS. Dural puncture was easier with the Sprotte 24 G cannula than with the less stable Quincke needle, as documented by a significantly shortened time for insertion of the cannula (4.6 +/- 2.6 vs 8.6 +/- 6.3 min, P less than 0.005). The total frequency of post-operative headache was 57% in the Vygon 29 G group and 25% in the Sprotte 24 G group; 21% of patients in the general anaesthesia group complained of headache. Frequency of postdural puncture headache, classified as being posture-related, was 25% in the 29 G Vygon group, compared with 11% in the 24 G Sprotte group (P = 0.148). When only moderate and severe postdural puncture headache was considered, there was a significant difference (25% vs. 4%; P = 0.026) in favour of the Sprotte cannula. DISCUSSION AND CONCLUSIONS. Thus, the 24 G Sprotte needle was at least as effective as the 29 G Vygon needle, and there is a suggestion that the former is more effective in minimising the incidence of moderate or severe postdural puncture headache.     

A new combined spinal–epidural apparatus: measurement of the distance to the epidural and subarachnoid spaces

A new combined spinal–epidural anaesthesia apparatus with a 27G lockable spinal needle was used in 151 patients. Two groups could be created, based on whether dural perforation was felt or not (group 1: with dural click; group 2: no dural click). Measurements of the epidural space depth and of the protrusion of the spinal needle from the epidural needle (tip-to-tip distance) were made. The mean depth of the epidural space was 5.59 cm. Correlations were found with body weight, weight-to-height ratio and body mass index (p < 0.001). The mean tip-to-tip distance measured was 7.0 mm in the patients of group 1, whereas in group 2 a distance of 8.9 mm was found. This difference was statistically significant. Correlations were found between the epidural space width and the patient's height, weight-to-height ratio and body mass index. Four patients felt paraesthesia during placement of the spinal needle and, in another four patients, aspiration was necessary to detect cerebrospinal fluid. Two patients needed epidural top-ups due to insufficient level of anaesthesia. The lockable spinal needle provides safe and stable conditions during injection and a high rate of success in reaching the subarachnoid space.     

Tip-holed spinal needle: a new design concept

Dura-arachnoid puncture for spinal anesthesia is associated with several complications. Postdural puncture headache (PDPH) and needle bending are significant among these. The incidence of PDPH has been reduced significantly with the advent of pencil-point needles. However, these needles also have their limitations, such as obstruction of the delivery port by tissues affecting both cerebrospinal fluid flash back and drug delivery. Increasing the size of the lateral hole has led to mechanical complications, such as tip bending. A new spreading beveled spinal needle tip has been designed to overcome the disadvantages of all the currently used spinal needles. To assess the feasibility, a 26-gauge Quincke spinal needle (B. Braun, Melsungen, Germany) has been modified manually. The new tip-holed design seems to be sound both from theoretical and practical point of view. Searching Medline Plus through their Internet Web site (www.nlm.nih.com) did not reveal the existence of any such spinal needle.     

Two-dimensional mapping to assess direction and magnitude of needle tip error in ultrasound-guided regional anaesthesia

We assessed whether echogenic needles reduce tip location error, by comparing three echogenic designs (Pajunk Sonoplex, Lifetech, B. Braun Stimuplex D+) with a non-echogenic control (Pajunk Uniplex), using a novel assessment technique in unembalmed human cadavers. Multiple images were taken of each needle at shallow (15 to 25 degrees), moderate (35 to 45 degrees) and steep (55 to 65 degrees) insertion angles. Twenty anaesthetists with varied experience in ultrasound-guided nerve blocks identified needle tip position and stated their confidence level in estimates. Actual tip position was determined at the time of image generation but concealed from the anaesthetists. Two-dimensional mapping of 'tip-error' involved measurement of the distance and orientation of each clinician's estimate of tip position in relation to the actual tip position. There were no significant differences in confidence or overall needle visibility at shallow insertion angles. At steeper angles, the Sonoplex showed significantly higher confidence and visibility scores. The remaining echogenic designs did not show any significant differences from the non-echogenic control. Objective measurements of tip error followed the same pattern as the subjective data, although were not universally significant. Two-dimensional mapping showed that as needle visibility deteriorated, so precise tip location was lost but the needle shaft/insertion path remained well-identified. As visibility deteriorated further, accuracy in this axis was also lost. When inaccurate, clinicians generally assessed the needle tip to be more superficial and inserted less far than it actually was. This has important implications for the safety of ultrasound-guided regional anaesthesia. Effective echogenic needle technology has the potential to address these concerns.     

Influence on hearing of 22 G Whitacre and 22 G Quincke needles

Audiograms were performed pre-operatively and 2 days postoperatively in 48 patients given spinal anaesthesia for transurethral resection of the prostate. Hearing levels were examined at 1000 Hz and below. Either 22 G standard design (Quincke) needles (n = 25) or 22 G pencil-point design (Whitacre) needles (n = 23) were used. Hearing loss of 10 dB or more at two or more frequencies were observed in six of 25 patients in the Quincke group and in two of 23 patients in the Whitacre group. The mean hearing level was more reduced in the Quincke group. The shape of the tip of the spinal needle seems to be of some importance to the effects on hearing level that may occur after spinal anaesthesia.