aDjunct bicarbonatE in Local anaesthesIa for CarpAl Tunnel rElease (DELICATE)


Kuopio University Hospital




Carpal Tunnel Syndrome


Other: Control arm
Other: Sodium bicarbonate

Study type


Funder types




Details and patient eligibility


Introduction Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome in Finland and worldwide. Nowadays carpal tunnel release (CTR) surgery is often done in local anaesthesia. Often the most painful event during CTR is the injection of the local anaesthetic. Multiple different methods have been trialed and buffering the local anaesthetic seems to have good results in reducing the pain caused by the injection. However, no study has buffered long-acting local anaesthetic in CTR surgery, and no study has accounted for the patient's individual pain tolerance in the groups. There are no comparisons of the results to minimal clinically important difference (MCID) for pain. Hypothesis In this study the investigators will evaluate the effects of buffering long-lasting local anaesthetic in wide-awake local anaesthesia no tourniquet (WALANT) CTR. This study's hypothesis is that buffering long-acting local anaesthetic with sodium bicarbonate decreases the pain of the injection. The investigators also expect that buffering will reduce the number of needle stings felt during injection, will result in as good perioperative pain control, will lengthen the effect of anaesthetic, will reduce postoperative painkiller usage, will have at least as good functional outcome and greater patient satisfaction. Methods This study will enlist 116 patients and divide the patients into two groups in this double blinded randomized controlled trial. One group receives non-buffered, and the second group buffered local anaesthetic. This study's primary outcome is to compare burning, pressure, needle sting and total pain the patient experienced between the groups. The investigators will assess this using VAS, and will compare the results to MCID. The investigators secondary outcomes are comparisons of expected injection pain level and pain during CTR with VAS, individual pain tolerance/catastrophising tendency with preoperative PCS-FINv2.0 form, the number of needle stings the patient feels during the injection, functional outcome and improvement of the patients' symptoms with The Boston Carpal Tunnel Questionnaire (Likert 5) before and after the surgery, evaluation of patient satisfaction with net promoter score (NPS) and the use of painkillers, duration of analgesia and pain levels using VAS after the surgery until the 3rd postoperative night.


116 estimated patients




18+ years old


No Healthy Volunteers

Inclusion criteria

  • Clinically and electrophysiologically diagnosed carpal tunnel syndrome
  • Patients who are scheduled for carpal tunnel release surgery.

Exclusion criteria

  • Associated disease or conditions, including earlier injury to median nerve, cervical radiculopathy, cubital tunnel syndrome and other peripheral neuropathy
  • Chronic renal failure
  • Rheumatoid arthritis
  • Allergies to lidocaine
  • Pregnancy
  • Profound cognitive impairment
  • Previous ipsilateral carpal tunnel decompression

Trial design

Primary purpose




Interventional model

Parallel Assignment


Quadruple Blind

116 participants in 2 patient groups

Non-buffered local anaesthetic
Other group
The investigators allocate 58 patients in this arm. It serves as the control group, who receives currently used local anaesthetic solution.
Other: Control arm
Buffered local anaesthetic
Experimental group
The investigators allocate 58 patients in this arm. It serves as the experimental group, who receives currently used anaesthetic solution that has been buffered.
Other: Sodium bicarbonate

Trial documents

Trial contacts and locations



Central trial contact

Yrjänä Nietosvaara, Prof.; Mikael Hytönen, MBBS

Data sourced from

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