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  Table of Contents 
Year : 2022  |  Volume : 23  |  Issue : 1  |  Page : 38-43

Preprocedural ultrasound assessment of landmarks of paramedian approach for subarachnoid block in geriatric population

Department of Anaesthesiology, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha, India

Date of Submission17-Jun-2021
Date of Decision17-Jun-2021
Date of Acceptance21-Aug-2021
Date of Web Publication23-Mar-2022

Correspondence Address:
Dr. Amrita Panda
Department of Anaesthesiology, Kalinga Institute of Medical Sciences, Bhubaneswar - 751 024, Odisha
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/TheIAForum.TheIAForum_97_21

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Background: Paramedian spinal anesthesia is the preferred anesthetic technique in the elderly. This conventional approach is occasionally challenged by difficulty in identifying landmarks accurately. Neuraxial ultrasound aims to overcome these inaccuracies.
Objective: The objective was that the routine use of preprocedural ultrasound assessment of landmarks for paramedian spinal in geriatric population improves the efficacy of spinal anesthesia by reducing the number of attempts and redirections.
Materials and Methods: Sixty consenting elderly patients aged 60 year or above, posted for elective surgery under spinal anesthesia, were enrolled in the study. Participants were assigned at random to receive spinal anesthesia by the paramedian approach by either conventional landmark guidance (Group CP) or preprocedural ultrasound-assisted (Group PP) technique.
Results: The number of needle redirections was not significant and the success rate at the first attempt with no redirection was higher in the ultrasound compared with the landmark group. However, the mean insertion attempts were indifferent. The preprocedural ultrasound-assisted approach required an insignificantly shorter time for administering spinal anesthesia than the landmark-guided technique (48.87s [67.65] vs. 50.67s [50.19]) [P = 0.90]. The periprocedural pain scores (2.90[2.07] vs. 2.87[1.57]) [P = 0.94] and willingness for a similar future intervention (66.7 vs. 66.7%) were comparable among the groups.
Conclusion: The use of preprocedural ultrasonography for paramedian approach to spinal anesthesia is not superior to the conventional landmark guidance in achieving successful dural tap at L3-L4 interspace in elderly adult population and should be limited to a setting with expert operators and selected patients for whom conventional methods may be technically challenging.

Keywords: Geriatric population, paramedian approach, preprocedural ultrasound, subarachnoid block

How to cite this article:
Ray TK, Saxena S, Panda A. Preprocedural ultrasound assessment of landmarks of paramedian approach for subarachnoid block in geriatric population. Indian Anaesth Forum 2022;23:38-43

How to cite this URL:
Ray TK, Saxena S, Panda A. Preprocedural ultrasound assessment of landmarks of paramedian approach for subarachnoid block in geriatric population. Indian Anaesth Forum [serial online] 2022 [cited 2023 Jan 31];23:38-43. Available from: http://www.theiaforum.org/text.asp?2022/23/1/38/340487

  Introduction Top

Success of spinal anesthesia is often eclipsed by difficult anatomical landmarks. Geriatric spine is notoriously unpredictable. Owing to an increased global life expectancy, geriatric surgical volume has proportionally increased. In the elderly, spinal anesthesia edges to be a near ideal anesthetic technique attributing to excellent operating conditions and better outcomes in terms of mortality, delirium, and minimizing postoperative respiratory complication.[1] However, selection and approach for the neuraxial technique is frequently challenged by the anatomical irregularities. Conventional landmark-guided paramedian approach is preferred.[2] More recently, neuraxial ultrasound for midline approach has possessed the merit of novelty. However, the routine utilization of ultrasound for subarachnoid block is questionable. Moreover, data to support use of ultrasound-assisted paramedian spinal anesthesia are underpowered and conflicting.

The current study aims to evaluate efficacy and efficiency of preprocedural ultrasound-guided paramedian approach to spinal anesthesia in the elderly in day-to-day anesthesia practice.

  Materials and Methods Top

The current randomized controlled study was validated by the institutional ethics committee of Kalinga Institute of Industrial Technology (KIIT) University (no. Kalinga Institute of Medical Sciences (KIMS)/KIIT/IEC/153/2018; on 19 September 2018) and was registered with Clinical Trials Registry-India (CTRI) at Ctri.nic.in (CTRI/2019/06/019620; Principal investigator: Dr. Shlok Saxena, Date of registration: 11 June 2019) prior to participant enrolment. Written informed consent was obtained from all participating subjects. This article has been prepared in accordance with the Consolidated Standards of Reporting Trials guidelines [Figure 1].[3]
Figure 1: CONSORT diagram

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Selection of participants

This study was conducted at Pradyumna Bal memorial Hospital, KIMS, Odisha, India, from September 2018 to September 2020. Each of the consenting participants aged at least 60 years scheduled to undergo elective surgery under spinal anesthesia belonging to the American Society of Anesthesiologists physical status I/II was enrolled. Patients with contraindications to spinal anesthesia, gross spinal deformity, previous spine surgeries, and neurological and psychiatric disorder were excluded from the study.

Randomization, blinding, and minimization of bias

All included patients were allocated into two groups of 30 each and were assigned at random to receive spinal anesthesia by the paramedian approach using either conventional landmark-guided (Group CP) or preprocedural ultrasound-guided (Group PP) technique based on a computer-generated block randomization in ratio of 1:1. A serially numbered, sealed opaque envelope was utilized for group concealment. Revelation of the group was made to only the attending anesthesiologist immediately prior to the procedure.

Landmarks were assessed by both palpation and by ultrasound guidance by a single trainee anesthesiologist (operator) blinded to group allocation. Operator expertise included <3 years of clinical experience in anesthesia and training in neuraxial ultrasound (<4 simulation hours) and having performed 18 ultrasound-guided subarachnoid blocks prior to this study. All spinal blocks were performed by a trainee anesthesiologist (excluding the operator). Observer was blinded to group allocation.

Study outcomes

The primary outcome was the number of needle redirections (described as the number of needle manipulations without exiting the skin).

The secondary outcomes included the following:

  1. Number of needle insertion attempts (re-entry of needle after complete withdrawal from skin)
  2. Time to administration of spinal anesthesia (the time from needle insertion to affirmation of cerebrospinal fluid (CSF) on dural puncture or the anesthesiologist's declaration of failed attempt and to use an alternative method)
  3. Periprocedural discomfort score on an 11-point numeric scale (0, no discomfort; 10, worst discomfort imaginable).

The outcomes were recorded by an observer who was blinded to the group allocation.

The numbers of redirections and insertion attempts were recorded until the demonstration of CSF. Patients were specifically asked to grade the discomfort on their back in the course of the entire neuraxial procedure.


All enrolled patients underwent a detailed preanesthesia checkup prior to surgery. On arrival to the operating room, standard monitors were attached.

In the sitting position, iliac crest, spinous process, and interspinous gaps were palpated and the quality of surface landmark was graded according to four-point scale (1 = easy, 2 = moderate, 3 = difficult, and 4 = impossible).

Needle insertion points were assessed by both palpation and ultrasound guidance in all patients and were labeled using a marker pen.

In the preprocedural ultrasound group, the skin marking was obtained using a standard linear transducer probe (5–10 Hz) of a portable ultrasound (Sonosite Edge II ultrasound system FUJIFILM Medical Systems, U. S. A.) by following a four-step systematic protocol.

  1. Neuraxial midline was identified and marked using the transverse midline view to aid the medial angulation of the needle and to gauge the distance from the midline to the point of paramedian insertion
  2. The sacrum was identified first in the transverse median view, using the 'counting-up' approach; then, the transducer was moved cephalad to identify lumbar (L) 3-L4 interspinous space [Figure 2]. A horizontal line was drawn through the midpoint of the short border of the probe when obtaining the clearest image of the ligamentum flavum–dura mater complex and the posterior aspect of vertebral body
  3. The probe was then placed in parasagittal oblique view to identify the interlaminar space, showing the posterior (ligamentum flavum, epidural space, and posterior dura) and anterior (anterior dura, posterior longitudinal ligament, and vertebral body) complexes as distinctly as possible [Figure 3]. With the probe positioned to obtain the clearest image, the skin was marked at the midpoints of the long borders of the probe to obtain a vertical line
  4. Both the horizontal and the vertical lines were extrapolated to find a point of intersection. The point of needle insertion for the preprocedural group was taken 1 cm caudal to this point.
Figure 2: Transverse View at L3-4 interspinous space

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Figure 3: Parasagittal oblique view

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In the conventional landmark group, landmarks were identified by placing the patient in sitting position, with the back actively flexed maximally. Then, the highest point on the iliac crest was palpated on either side and a line adjoining the two points was obtained. This line was assumed to pass through the L4 vertebral body or L4-L5 interspace. Subsequently, L3-4 interspace was identified by counting upward. Insertion point for conventional landmark group was identified by marking a point 1 cm lateral and 1 cm inferior to the tip of L4 spinous process. The angle of insertion was taken as 15 degrees for all participants. Participant was asked to maintain posture and limit their movement.

A trainee anesthesiologist was then allocated to perform the spinal anesthesia. The group allocation was revealed to him and the approximate angle of insertion was conveyed. Skin surface was cleaned, and local anesthetic solution (2 ml of 2% lignocaine) was infiltrated. Under all aseptic precaution, without palpating, lumbar puncture was performed at the marked space [Figure 4] using the identified point of insertions with a 25 G Quincke needle (TaeChang Industrial Co., Gongju, Republic of Korea). Successful dural puncture was confirmed with clear and free flow of CSF.
Figure 4: Point of needle insertion– (A) Landmark guided, (B) USG guided

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Statistical analysis

Statistical analysis was done using the SPSS software for Windows (version 20.0; IBM Corp., Armonk, New York, USA) and P ≤ 0.05 was considered statistically significant. Data for continuous variables were presented as mean ± standard deviation (SD) and the categorical variables as frequency and percentage. Student's t-test was used to test the significance in difference between two groups.

Sample size calculation

A pilot study was conducted to assess the sample size for our study. Twelve patients were enrolled and randomized in blocks of 1:1 to receive spinal anesthesia either by the conventional landmark-guided paramedian approach (Group CP) or by preprocedural ultrasound-guided paramedian approach (Group PP). The needle redirection attempts were (mean ± SD) 1.5 ± 0.5 in group PP compared to 2 ± 0.81 in group CP. At a 5% level of significance, 90% power, and 95% confidence, at least 25 participants were required in each group. Allowing for dropouts, 30 patients were included in each group, i.e., a total sample size was 60.

  Results Top

Sixty participants who fulfilled the eligibility criteria were randomized and completed the study. The patients aged 66.21 + 5.45 were posted for a variety of elective surgical and orthopedic cases. Demographic characteristics were comparable among the two groups [Table 1]. The mean numbers of needle redirections (2.20 + 2.70 vs. 2.83 + 2.45) and needle insertion attempts (1.47 + 0.97 vs. 1.57 + 0.94) required for dural puncture were slightly lower in the ultrasound group than in the landmark group. However, this difference was statistically insignificant [insertion attempts: P =0.68 and redirections: P =0.34; [Table 2]]. For all patients, dural puncture was achieved within two attempts. The rate of successful dural puncture at first attempt-first pass [30% vs. 13%; [Table 2]] was greater in the ultrasound group, suggesting higher incidence of redirections in the landmark group. Redirections often involved only a few adaptations of the medial–lateral angulation.
Table 1: Baseline characteristics

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Table 2: Characteristics of the procedure

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Time to achieve a dural puncture was lesser with the landmark assessed by ultrasound guidance compared to the conventional palpation approach [Table 2].

Patients in the preprocedural ultrasound-guided group reported similar periprocedural pain discomfort scores as those in the conventional landmark group [Table 2]. Adequate spinal block was achieved for surgical procedure in all participants.

  Discussion Top

This trial indicates that the use of neuraxial ultrasonography has limited desirability and offers no advantage over landmark-guided paramedian technique in reducing technical difficulty among elderly population. The number of attempts and needle redirections were similar with no difference in block-associated pain. There was no significant difference in the time taken for the procedure among the groups.

Utility of paramedian approach of spinal anesthesia in elderly population is time tested with supporting literature and is commonly practiced.[5] The challenges faced due to aging-related physiological changes in the spine in elderly are overcome by this technique offering advantage over the midline approach.

Recently, neuraxial ultrasound has gained popularity and has ascertained its benefits. Several reports support that the use of ultrasonography for paramedian technique was superior to the midline technique for central neuraxial blocks in the elderly.[2],[6],[7],[8]

We believe that to validate the true benefit of ultrasonography in elderly population, a comparison such as the conventional landmark-guided paramedian approach may be more appropriate. Thereby, we purposefully compared the use of ultrasound-guided paramedian approach with conventional landmark-guided paramedian approach. As a result, our data indicate that ultrasound offers no technical aid for spinal anesthesia in the elderly. Our findings are consistent with the earlier study, which showed that routine use of preprocedure ultrasound-guided paramedian spinal performed at the L5-S1 level did not reduce the number of attempts required to achieve a successful spinal anesthesia.[9]

The use of ultrasound assistance in patients with easily palpable spines and in pregnant women had shown no benefit.[9],[10] The current study supports the previous findings as participants had low BMI (25.2 + 5.75) and a majority of our patients (86.7%) had easily palpable landmarks.

Although several studies have reported no significant improvement with the use of neuraxial ultrasonography others have found to improve efficacy, efficiency, and comfort.[10],[11],[12],[13],[14],[15] In a study by SyungKun Park et al., old patients with easily palpable landmarks significantly benefitted and reported higher satisfaction with the use of neuraxial ultrasound.[16] In spite of the eliminating the operator skill-dependent variability of scanning time and observing only the procedure time, we found that the time taken was marginally shorter in the ultrasound group, which may not be of clinical relevance. In spite of eliminating the operator skill-dependent variability of scanning time and observing only the procedure time, we found that the time taken was marginally shorter in the ultrasound group, which is of no clinical relevance. As attractive it may be, to receive information of the anatomy with the use of ultrasound, we did not find it beneficial, as the time taken to administer spinal anesthesia by our trainees did not significantly differ among the two groups.

A study by Srinivasan et al. demonstrated no significant difference in the time taken for administration of spinal block with the use of neuraxial ultrasonography.[8] However, certain other studies differed by reporting a significant decrease in the spinal administer time with the use of preprocedural ultrasound.[16],[17]

The merit of this study, by the virtue of its results, negates the routine use of preprocedure neuraxial scanning for spinal anesthesia in geriatric patients.


In the current study, the attending anesthesiologist relied upon approximation of angle to guide the needle insertion and may have found it difficult to follow the trajectory as conveyed by the sonologist.

Landmark assessment using ultrasonography is influenced by skill of the operator and technical difficulty. We did not record the scanning time owing to its variability among participants. This may have led to undermine the time taken in the study group.

The operator in our study had performed 18 ultrasound neuraxial procedures prior to this study. As noted by Kopacz et al., a notable improvement in the spinal anesthesia technique among novice residents requires at least 20 procedures to be performed. However, a potential learning effect over the course of the study could be present.[18]

Furthermore, elderly individuals with loose skin may inherit inaccuracies. In addition, study participants had a relatively low BMI. Hence, generalizability of our results for larger adults may be inappropriate.

  Conclusion Top

Ultrasound-assisted paramedian spinal anesthesia does not reduce the number of needle manipulations required for successful dural puncture nor does it decrease periprocedural patient discomfort compared with the conventional landmark-guided paramedian technique in the elderly. Our results suggest that the neuraxial ultrasonography does not improve the efficacy and comfort of spinal anesthesia in the elderly and should be limited to a setting with expert operators and selected patients for whom conventional methods may be technically challenging.


We would like to thank faculty of the Department of Anesthesia and Department of Research and Development KIMS for their guidance throughout the study and Mrs. Subhadra Priyadarshini for her help with statistical analysis.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Ahn EJ, Kim HJ, Kim KW, Choi HR, Kang H, Bang SR. Comparison of general anaesthesia and regional anaesthesia in terms of mortality and complications in elderly patients with hip fracture: A nationwide population-based study. BMJ Open 2019;9:e029245.  Back to cited text no. 1
Rabinowitz A, Bourdet B, Minville V, Chassery C, Pianezza A, Colombani A, et al. The paramedian technique: A superior initial approach to continuous spinal anesthesia in the elderly. Anesth Analg 2007;105:1855-7, table of contents.  Back to cited text no. 2
Schulz KF, Altman DG, Moher D; CONSORT Group. CONSORT 2010 Statement: Updated guidelines for reporting parallel group randomised trials. BMC Med 2010;8:18.  Back to cited text no. 3
Britannica, The Editors of Encyclopaedia. “Student's t-test”. Encyclopedia Britannica, 27 May. 2020, https://www.britannica.com/science/Students-t-test. Accessed 9 November 2021.  Back to cited text no. 4
Zhurda T, Kërçi M, Bajraktari M, Muzha D, Kurti B. The advantages of paramedian approach for spinal anesthesia of elderly patients in urology surgery: 8AP2–2. Eur J Anaesthesiol 2010;27:130.  Back to cited text no. 5
Ahsan-Ul-Haq M, Amin S, Javaid S. Paramedian technique of spinal anesthesia in elderly patients for hip fracture surgery. J Coll Physicians Surg Pak 2005;15:160-1.  Back to cited text no. 6
Leeda M, Stienstra R, Arbous MS, Dahan A, Th Veering B, Burm AG, et al. Lumbar epidural catheter insertion: The midline vs. the paramedian approach. Eur J Anaesthesiol 2005;22:839-42.  Back to cited text no. 7
Blomberg RG, Jaanivald A, Walther S. Advantages of the paramedian approach for lumbar epidural analgesia with catheter technique. A clinical comparison between midline and paramedian approaches. Anaesthesia 1989;44:742-6.  Back to cited text no. 8
Srinivasan KK, Leo AM, Iohom G, Loughnane F, Lee PJ. Pre-procedure ultrasound-guided paramedian spinal anaesthesia at L5-S1: Is this better than landmark-guided midline approach? A randomised controlled trial. Indian J Anaesth 2018;62:53-60.  Back to cited text no. 9
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Ansari T, Yousef A, El Gamassy A, Fayez M. Ultrasound-guided spinal anaesthesia in obstetrics: Is there an advantage over the landmark technique in patients with easily palpable spines? Int J Obstet Anesth 2014;23:213-6.  Back to cited text no. 11
Kallidaikurichi Srinivasan K, Iohom G, Loughnane F, Lee PJ. Conventional landmark-guided midline versus preprocedure ultrasound-guided paramedian techniques in spinal anesthesia. Anesth Analg 2015;121:1089-96.  Back to cited text no. 12
Chin A, Crooke B, Heywood L, Brijball R, Pelecanos AM, Abeypala W. A randomised controlled trial comparing needle movements during combined spinal-epidural anaesthesia with and without ultrasound assistance. Anaesthesia 2018;73:466-73.  Back to cited text no. 13
Abdelhamid SA, Mansour MA. Ultrasound-guided intrathecal anesthesia: Does scanning help? Egypt J Anaesth 2013;29:389-94.  Back to cited text no. 14
Grau T, Leipold RW, Conradi R, Martin E. Ultrasound control for presumed difficult epidural puncture. Acta Anaesthesiol Scand 2001;45:766-71.  Back to cited text no. 15
Park SK, Yoo S, Kim WH, Lim YJ, Bahk JH, Kim JT. Ultrasound-assisted vs. landmark-guided paramedian spinal anaesthesia in the elderly: A randomised controlled trial. Eur J Anaesthesiol 2019;36:763-71.  Back to cited text no. 16
Kampitak W, Werawatganon T, Uerpairojkit K, Songthamwat B. Paramedian spinal anesthesia: Landmark vs. Ultrasound-guided approaches. J Anesth Clin Res 2018;09:837. [doi: 10.4172/2155-6148.1000837].  Back to cited text no. 17
Kopacz DJ, Neal JM, Pollock JE. The regional anesthesia “learning curve”. What is the minimum number of epidural and spinal blocks to reach consistency? Reg Anesth 1996;21:182-90.  Back to cited text no. 18


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1], [Table 2]


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