Simultaneous Application of Lidocaine and Ketamine During Ambulatory Infusion Therapy: A Retrospective Analysis

Figures & data

Table 1. Pain reduction score.

Variable	Any pain reduction^†, points	Pain reduction ≥50%, points	Pain-free, points	Increase in pain, points
No quantifiable amount of time	1	2	3	‐1
<2 weeks	2	3	4	‐1
≥2 weeks	3	4	5	‐1
Time between infusions	4	5	6	‐1

Scoring system: The first row represents the amount of pain reduction patients experienced through infusion therapy. The first column represents the duration of pain reduction was in between infusions.- Patients experiencing an increased amount of pain were only able to receive negative points. Group allocation: increased pain (-1 point), minor impact (1–2 points), moderate impact (3–4 points), high impact (5–6 points).

† Defined as pain reduction that was not further specified by the patient.

Figure 1. Flowchart of patient selection.

Table 2. Patient demographics and baseline characteristics.

Characteristic	Patients
Age, years, mean ± SD	51.426 ± 0.835
Sex, n (%)   Female   Male	153 (48) 166 (52)
Nationality, n (%)   Swiss   Other   Unknown	195 (61.1) 122 (38.2) 2 (0.6)
Education, n (%)   Common labor   Completed apprenticeship   University   Unknown	58 (18.2) 87 (27.3) 19 (6) 155 (48.6)
Religion, n (%)   Christian, reformed   Catholic   Muslim   Jewish   No religious affiliation   Unknown	47 (14.7) 67 (21) 35 (11) 1 (0.3) 87 (27.3) 82 (25.7)
Disability pension status, n (%)   granted   in process   denied   No application for pension   Missing	59 (18.5) 91 (28.5) 4 (1.3) 67 (21) 98 (30.7)
Actively employed patients, n (%)	14 (4.4)

SD: Standard deviation.

Table 3. Medical diagnoses.

Pain type	Diagnoses, n (%)^†
Chronic neuropathic pain	181 (56.7)
Chronic postsurgical or post-traumatic pain	110 (34.5)
Chronic primary pain	34 (10.7)
Chronic cancer-related pain	22 (6.9)
Chronic secondary visceral pain	8 (2.5)
Chronic secondary headache or orofacial pain	5 (1.6)
Other specified chronic pain	4 (1.3)
Chronic pain, unspecified	4 (1.3)
Complex regional pain syndrome (CRPS)	19 (6)

† Data refer to number of diagnoses, not number of patients (multiple entries per patient are possible), with percentage of diagnosed patients in parentheses. A total of 19 patients were diagnosed with chronic regional pain syndrome. No distinction was made between types I and II.

Table 4. Psychiatric diagnoses.

Diagnosis	Diagnoses, n (%)^†
Depressive disorder   Minor   Moderate   Severe   Not stated	81 (25.4) 7 (2.2) 27 (8.5) 7 (2.2) 40 (12.5)
Personality disorders and related traits	13 (4.1)
Post-traumatic stress disorder	13 (4.1)
Anxiety or fear-related disorders	7 (2.2)
Harmful pattern of use of sedatives, hypnotics or anxiolytics	4 (1.3)
Harmful pattern of use of alcohol	7 (2.2)
Harmful pattern of use of opioids	7 (2.2)
Unknown	216 (67.7)

† Data refer to number of diagnoses, not number of patients (multiple entries per patient are possible), with percentage of diagnosed patients in parentheses.

Figure 2. Mean lidocaine and ketamine dose over infusion intervals.

Labels on x-axes show number of received infusions.

BW: Body weight.

Table 5. Side effects.

Side effect	n (%)
Dizziness	130 (22.8)
Waking reactions	120 (21)
Mild CNS effects	95 (16.6)
Hypertension	88 (15.4)
Nausea and emesis	43 (7.5)
Anxiety	33 (12.5)
Respiratory depression	13 (2.3)
Tachycardia	12 (2.1)
Hypotension	8 (1.4)
Nystagmus and tonic and clonic movements	2 (0.4)
Bradycardia	1 (0.2)
Elevated liver enzymes	1 (0.2)

Hypertension and hypotension were defined as mean arterial pressure over 106.67 mm Hg or under 70 mm Hg, respectively, and a rise or decrease in mean arterial pressure of at least 25% compared with mean arterial pressure at start of infusion. Tachycardia and bradycardia were defined as rise or fall in pulse of at least 25% compared with pulse at start of infusion. Mild CNS effects were defined as dysarthria, tinnitus, vision disorder and numbness of tongue.

Figure 3. Number of recieved infusions and pain reduction scores refered to International Classification of Diseases 11th Revision Diagnosis.

(A) Total number of infusions. (B) Median pain reduction score refered to International Classification of Diseases 11th Revision diagnosis.

CRPS: Complex regional pain syndrome; MSK: Musculoskeletal.

Figure 4. Median number of days with any pain reduction.

(A) Over intervals between infusions (e.g., 1 stands for days of pain reduction between first and second infusions). (B) Over International Classification of Diseases 11th Revision diagnosis.

CRPS: Complex regional pain syndrome; MSK: Musculoskeletal.

Table 6. Pain medication.

Medication prior to infusions	n (%)
Gabapentinoids	120 (37.6)
NSAIDs, paracetamol, metamizole	95 (29.8)
Opioids	43 (13.5)
Reduction in pain medication   Gabapentinoids   NSAIDs, paracetamol, metamizole   Opioids	17 (5.3) 15 (4.7) 34 (10.7)
Increase in pain medication	32 (10)