Local Anesthetics
Conditions
Keywords
pain pH local anesthetics
Brief summary
When one receives a local anesthetic, such as novocaine for a dental procedure, there is a burning painful sensation experienced upon injection of the local anesthetic. We are trying to understand the role of pH (how acidic a solution is) in the production of pain during local anesthetic administration. We hypothesize that less acidic solutions produce less burning. We also want to determine whether or not the pH of the solution affects the rate of onset of the local anesthesia. We will recruit subjects from patients who have a clinical indication for lumbar medial branch (LMB) nerve blocks, procedures frequently performed at the Massachusetts General Hospital Center for Pain Medicine. For each patient, three nerve blocks are administered at adjacent spinal levels, typically using either lidocaine or bicarbonate-buffered lidocaine as the local anesthetic. We will add a saline control as part of the research procedure and then provide lidocaine at the control location before continuing with the nerve blocks. This clinical procedure offers an ideal opportunity to compare the effects of the three solutions. There will be almost no deviation from the standard clinical procedure. After the injection of each solution, the pain score on administration of the medication will be recorded immediately. We will also provide a continuous stimulation (pin taps) after the local anesthetic injection and record when the patient experiences hypoesthesia (reduced sensation) and anesthesia (absent sensation). Finally, we will record the pain score upon reinsertion of a needle to mark the precise location (part of the clinical procedure) one minute after the local anesthetic injection. All data will be collected during the a single clinical visit. The study will conclude when 60 subjects have successfully been tested. Data will be reviewed annually.
Interventions
DRUGLidocaine
1 ml subcutaneous injection of 0.9% lidocaine, given once
DRUGnormal saline
1 ml subcutaneous injection 0.9% sodium chloride, given once
1 ml subcutaneous injection of 0.9% lidocaine and 0.84% sodium bicarbonate
Sponsors
Massachusetts General Hospital
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Caregiver)
Eligibility
Sex/Gender
ALL
Age
19 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* patients at MGH Center for Pain Medicine who have clinical indication for undergoing diagnostic medial branch block of nerves to facet joints.
Exclusion criteria
* contraindication to the clinical procedure * do not speak English
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Rank-transformed Pain Score | immediate, upon injection of each solution | Pain score upon injection of local anesthetic: the pain score is a validated 11-point numeric rating scale in which patients rate pain between 0 (no pain) and 10 (worst pain imaginable). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Rank-transformed Time (Seconds) Until Hypoesthesia | 0-180 seconds after each injection. | Rank-transformed time (seconds) until hypoesthesia will be assessed using a sensory stimulus |
| Rank-transformed Time (Seconds) Until Anesthesia | 0-180 seconds after each injection | Rank-transformed time (seconds) until anesthesia will be assessed using a repeated sensory stimulus. |
| Rank-transformed Pain Score Upon Needle Stick. | 1 minute after each injection | Pain score upon needle stick: The pain score is a validated 11-point numeric rating scale in which patients rate pain between 0 (no pain) and 10 (worst pain imaginable). |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| All Study Participants All study participants | 29 |
| Total | 29 |
Baseline characteristics
| Characteristic | All Study Participants |
|---|---|
| Age, Continuous | 54.5 years |
| Baseline Pain Score | 6 units on a scale |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 17 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 11 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 29 Participants |
| Region of Enrollment United States | 29 participants |
| Sex: Female, Male Female | 13 Participants |
| Sex: Female, Male Male | 16 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — | — / — |
| other Total, other adverse events | 0 / 29 | 0 / 29 | 0 / 29 |
| serious Total, serious adverse events | 0 / 29 | 0 / 29 | 0 / 29 |
Outcome results
Primary
Rank-transformed Pain Score
Pain score upon injection of local anesthetic: the pain score is a validated 11-point numeric rating scale in which patients rate pain between 0 (no pain) and 10 (worst pain imaginable).
Time frame: immediate, upon injection of each solution
| Arm | Measure | Group | Value (LEAST_SQUARES_MEAN) |
|---|---|---|---|
| Normal Saline | Rank-transformed Pain Score | Difference compared to control | 0 rank |
| Normal Saline | Rank-transformed Pain Score | Rank-transformed pain score | 1.97 rank |
| Normal Saline | Rank-transformed Pain Score | Difference compared to lidocaine | -0.138 rank |
| Lidocaine | Rank-transformed Pain Score | Difference compared to control | 0.138 rank |
| Lidocaine | Rank-transformed Pain Score | Rank-transformed pain score | 2.10 rank |
| Lidocaine | Rank-transformed Pain Score | Difference compared to lidocaine | 0 rank |
| Alkalinized Lidocaine | Rank-transformed Pain Score | Rank-transformed pain score | 1.93 rank |
| Alkalinized Lidocaine | Rank-transformed Pain Score | Difference compared to lidocaine | -0.172 rank |
| Alkalinized Lidocaine | Rank-transformed Pain Score | Difference compared to control | -0.034 rank |
Comparison: Analysis: Non-parametric Friedman ANOVA test on rank-transformed outcome with Bonferroni correction for pairwise comparisons.~Null hypothesis: No difference between the groupsp-value: 0.7535non-parametric Friedman ANOVA test
Secondary
Rank-transformed Pain Score Upon Needle Stick.
Pain score upon needle stick: The pain score is a validated 11-point numeric rating scale in which patients rate pain between 0 (no pain) and 10 (worst pain imaginable).
Time frame: 1 minute after each injection
| Arm | Measure | Group | Value (LEAST_SQUARES_MEAN) |
|---|---|---|---|
| Normal Saline | Rank-transformed Pain Score Upon Needle Stick. | Difference compared to control | 0 rank |
| Normal Saline | Rank-transformed Pain Score Upon Needle Stick. | Rank-transformed pain score | 2.72 rank |
| Normal Saline | Rank-transformed Pain Score Upon Needle Stick. | Difference compared to lidocaine | 1.09 rank |
| Lidocaine | Rank-transformed Pain Score Upon Needle Stick. | Difference compared to control | -1.09 rank |
| Lidocaine | Rank-transformed Pain Score Upon Needle Stick. | Rank-transformed pain score | 1.64 rank |
| Lidocaine | Rank-transformed Pain Score Upon Needle Stick. | Difference compared to lidocaine | 0 rank |
| Alkalinized Lidocaine | Rank-transformed Pain Score Upon Needle Stick. | Rank-transformed pain score | 1.64 rank |
| Alkalinized Lidocaine | Rank-transformed Pain Score Upon Needle Stick. | Difference compared to lidocaine | 0 rank |
| Alkalinized Lidocaine | Rank-transformed Pain Score Upon Needle Stick. | Difference compared to control | -1.09 rank |
Comparison: Analysis: Non-parametric Friedman ANOVA test on rank-transformed outcome with Bonferroni correction for pairwise comparisons.~Null hypothesis: No difference between the groupsp-value: <0.0001non-parametric Friedman ANOVA test
Secondary
Rank-transformed Time (Seconds) Until Anesthesia
Rank-transformed time (seconds) until anesthesia will be assessed using a repeated sensory stimulus.
Time frame: 0-180 seconds after each injection
| Arm | Measure | Group | Value (LEAST_SQUARES_MEAN) |
|---|---|---|---|
| Normal Saline | Rank-transformed Time (Seconds) Until Anesthesia | Difference compared to control | 0 rank |
| Normal Saline | Rank-transformed Time (Seconds) Until Anesthesia | Rank-transformed time (s) | 2.90 rank |
| Normal Saline | Rank-transformed Time (Seconds) Until Anesthesia | Difference compared to lidocaine | 1.28 rank |
| Lidocaine | Rank-transformed Time (Seconds) Until Anesthesia | Difference compared to control | -1.28 rank |
| Lidocaine | Rank-transformed Time (Seconds) Until Anesthesia | Rank-transformed time (s) | 1.62 rank |
| Lidocaine | Rank-transformed Time (Seconds) Until Anesthesia | Difference compared to lidocaine | 0 rank |
| Alkalinized Lidocaine | Rank-transformed Time (Seconds) Until Anesthesia | Rank-transformed time (s) | 1.48 rank |
| Alkalinized Lidocaine | Rank-transformed Time (Seconds) Until Anesthesia | Difference compared to lidocaine | -0.14 rank |
| Alkalinized Lidocaine | Rank-transformed Time (Seconds) Until Anesthesia | Difference compared to control | -1.41 rank |
Comparison: Analysis: Non-parametric Friedman ANOVA test on rank-transformed outcome with Bonferroni correction for pairwise comparisons.~Null hypothesis: No difference between the groupsp-value: <0.0001non-parametric Friedman ANOVA test
Secondary
Rank-transformed Time (Seconds) Until Hypoesthesia
Rank-transformed time (seconds) until hypoesthesia will be assessed using a sensory stimulus
Time frame: 0-180 seconds after each injection.
| Arm | Measure | Group | Value (LEAST_SQUARES_MEAN) |
|---|---|---|---|
| Normal Saline | Rank-transformed Time (Seconds) Until Hypoesthesia | Difference compared to control | 0 rank |
| Normal Saline | Rank-transformed Time (Seconds) Until Hypoesthesia | Rank-transformed time (s) | 2.95 rank |
| Normal Saline | Rank-transformed Time (Seconds) Until Hypoesthesia | Difference compared to lidocaine | 1.48 rank |
| Lidocaine | Rank-transformed Time (Seconds) Until Hypoesthesia | Difference compared to control | -1.48 rank |
| Lidocaine | Rank-transformed Time (Seconds) Until Hypoesthesia | Rank-transformed time (s) | 1.47 rank |
| Lidocaine | Rank-transformed Time (Seconds) Until Hypoesthesia | Difference compared to lidocaine | 0 rank |
| Alkalinized Lidocaine | Rank-transformed Time (Seconds) Until Hypoesthesia | Rank-transformed time (s) | 1.59 rank |
| Alkalinized Lidocaine | Rank-transformed Time (Seconds) Until Hypoesthesia | Difference compared to lidocaine | 0.121 rank |
| Alkalinized Lidocaine | Rank-transformed Time (Seconds) Until Hypoesthesia | Difference compared to control | -1.36 rank |
Comparison: Analysis: Non-parametric Friedman ANOVA test on rank-transformed outcome with Bonferroni correction for pairwise comparisons.~Null hypothesis: No difference between the groupsp-value: <0.0001non-parametric Friedman ANOVA test