A Comparison of CoolStick With Ethyl Chloride for the Assessment of Light Touch

February 26, 2026 updated by: Barts & The London NHS Trust

A Comparison of CoolStick and Ethyl Chloride Spray for the Assessment of Sensory Block to Light Touch and Cold Before Caesarean Section Under Spinal or Combined Spinal-epidural Anaesthesia

The main aim of this study is to compare CoolStick to ethyl chloride spray for the assessment of light touch following neuraxial anaesthesia for caesarean delivery.

Coolstick and ethyl chloride will also be compared for the assessment of cold sensation.

Participants will also be asked whether they experienced any intraoperative pain.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

In England, up to 35% of deliveries in 2022 were by caesarean section. Current guidelines from NICE recommend that regional anaesthesia is offered for caesarean section. Neuraxial anaesthesia is considered to carry less risk of morbidity than general anaesthesia for both mother and neonate and is performed for approximately 92% of caesarean sections. To ensure the comfort of the mother, and to avoid intraoperative pain that could lead to general anaesthesia conversion, the neuraxial block is tested prior to commencing surgery. In the United Kingdom, the Royal College of Anaesthetists recommend that less than 1% of elective caesarean sections started under regional anaesthesia are converted to general anaesthesia.

Surveys of UK anaesthetists have found a wide range of practices when assessing neuraxial block, including the testing of light touch, temperature, pain and motor block. In a survey of UK anaesthetists, cold has been shown to be the most widely used modality for testing with 92% of respondents testing this modality. This was followed by touch, which 60% of respondents tested for. Recent consensus guidance from the Obstetric Anaesthetists' Association has recommended light touch as the primary testing modality for neuraxial anaesthesia for caesarean section, aiming for a sensory block to the T5 level or above. A second testing modality is recommended in cases where there is doubt over the light touch assessment. In practice, many anaesthetists will consider anaesthesia to be adequate when block to light touch is demonstrated to the T5 level or above and cold to the T4 level or above.

Ethyl chloride spray is the most common piece of equipment for used for testing in the UK. It has been shown that ethyl chloride spray can be used for the assessment of light touch and is equivalent to established methods when assessing adequacy of the block for surgery. However, ethyl chloride has disadvantages: skin irritation and allergic reactions sometimes occur; and containers are expensive, require replacing and carry a carbon footprint. The spray also remains in the atmosphere for up to two months and this can have a deleterious effect on the environment.

Cotton wool has been shown to be as effective at testing light touch when compared to more expensive methods. However, it is not necessarily practical to have multiple pieces of equipment required to assess different block modalities. Given that ethyl chloride is commonly used to test both modalities, a more sustainable and cost-effective approach to testing both light touch and cold would be ideal.

Theophany Limited recently developed the CoolStick for assessment of block height to cold. The CoolStick consists of a stainless-steel head and a plastic handle. It is kept in the fridge before use and is cleaned with an antibacterial wipe between patients. The CoolStick maintains a temperature adequate for cold assessment for up to 10 minutes in ambient theatre temperature and should be kept refrigerated for at least 40 minutes prior to use. It appears to be a more sustainable and cost-effective alternative to ethyl chloride spray; however, there are no studies that demonstrate its clinical application in this setting.

The primary aim of this study is to compare Coolstick with ethyl chloride spray for the assessment of light touch, with the secondary aim of comparing CoolStick to ethyl chloride for the assessment of cold.

Study Type

Observational

Enrollment (Actual)

64

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United Kingdom
      • London, United Kingdom
        • The Royal London Hospital
      • London, United Kingdom
        • Newham University Hospital
      • London, United Kingdom
        • Whipps Cross University Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

N/A

Sampling Method

Probability Sample

Study Population

All eligible patients presenting for elective caesarean section will be invited to participate in the study.

Description

Inclusion Criteria:

  • Pregnant patients presenting for elective caesarean section under spinal or combined spinal-epidural anaesthesia.

Exclusion Criteria:

  • < 18 years old
  • Unwilling or unable to give informed consent
  • Inability to understand written and/or verbal English
  • Allergy to stainless steel
  • Allergy to ethyl chloride spray

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
All participants
All participants will receive standard care with the addition of extra assessment of block from neuraxial anaesthesia
Other: CoolStick
Assessment of block using CoolStick.
Other: Ethyl Chloride
Assessment of block using ethyl chloride spray
Other: Question
Participant will be asked if they felt pain or not.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Light Touch
Time Frame: 6 months
The dermatomal block level to light touch at 10 minutes after spinal injection measured using CoolStick and Ethyl Chloride spray.
6 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cold
Time Frame: 6 months
The dermatomal block level to cold at 10 minutes after spinal injection measured using CoolStick and Ethyl Chloride spray.
6 months

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Intraoperative pain
Time Frame: 6 months
The presence of intraoperative pain within 60 minutes of the spinal injection. The options will be 'yes' or 'no'.
6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Barts & The London NHS Trust

Investigators

  • Study Chair: Matthew Wikner, Barts & The London NHS Trust

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 1, 2025

Primary Completion (Actual)

January 29, 2026

Study Completion (Actual)

January 29, 2026

Study Registration Dates

First Submitted

August 22, 2024

First Submitted That Met QC Criteria

September 11, 2024

First Posted (Actual)

September 19, 2024

Study Record Updates

Last Update Posted (Actual)

February 27, 2026

Last Update Submitted That Met QC Criteria

February 26, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 331686

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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