Rationale and Objectives
Percutaneous liver biopsy for tumors performed under local anesthesia is still a painful procedure. The aim of this study was to evaluate the patient’s reaction and the analgesic efficacy and safety of an equimolar mixture of oxygen and nitrous oxide (EMONO) inhalation.
Materials and Methods
A monocenter, prospective, randomized and double-blind controlled study was performed including 99 adult patients undergoing ultrasound controlled liver biopsy for tumors. 50 patients received an EMONO and 49 patients received a placebo. Pain was evaluated by patients before and after the procedure using a Visual Analog Scale.
Results
Analgesic control, defined by the difference between the final and initial VAS scores (Δ), was significantly better in the EMONO group than in the placebo group (Δ = 17.8 ± 25.5 mm vs 30.1 ± 32.6 mm; P = .045. The number of patients who would agree to undergo another liver biopsy under the same conditions was significantly higher in the EMONO group than the placebo group (92.0% vs 75.5%, P = .026). There were no side-effects from the administration of an EMONO.
Conclusion
This study shows that patients receiving an EMONO had a higher analgesic control after percutaneous biopsy of focal liver lesions than patients in the placebo group. Moreover, acceptance of additional biopsies was higher in the EMONO group.
Despite improvements in imaging techniques for the characterization of liver lesions, percutaneous biopsy of focal liver lesions is still often necessary in clinical practice. As the position paper of the American Association for the Study of Liver Diseases (AASLD) pointed out, liver biopsy should be considered in patients whose diagnosis is uncertain, and when a more specific diagnosis is likely to modify the therapeutic management plan . Indications for liver biopsy depend on the patient’s specific clinical history and imaging findings , but they are mainly: 1) atypical liver lesions in patients with underlying liver disease especially cirrhosis , 2) atypical liver lesions in patients with known extrahepatic cancer, or 3) incidental liver lesions not characterized on extensive imaging .
Percutaneous liver biopsy for tumors is performed under local anesthesia and with conscious sedation in most patients before the procedure . Nevertheless, Eisenberg et al have reported that 69% of the patients have pain immediately after the procedure, more than half are still in pain 4 hours later, and nearly 40% 24 hours after the procedure . These authors have shown that sedation with standard premedication and local anesthesia fails to produce sufficient immediate and late analgesia . Although this issue is not usually considered to be significant, patients with negative biopsies often require additional biopsies and some may refuse this procedure.
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Materials and methods
Study Design
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Biopsy Procedure
Premedication
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Treatment Administration
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Biopsy Samples
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Procedure Evaluation
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Statistical Methodology
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Results
Enrollment
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Demographics and Baseline Patient Characteristics
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Table 1
Demographic Patient Characteristics
Patients EMONO ( n = 50) Placebo ( n = 49)P Value Sex ratio (M/F) 28/22 30/19 .598 Mean age (y) 53.6 ± 12.2 57.2 ± 15.1 .189 With chronic background pain 6 (12.0%) 4 (8.2%) .239 Mean VAS before the procedure (mm) (minimum, maximum) 6.8 ± 18.2 0, 83 6.0 ± 19.9 0, 95 .458
EMONO, equimolar mixture of oxygen and nitrous oxide; VAS, visual analog scale.
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Table 2
Characteristics of the Lesions
Lesion Characteristics EMONO ( n = 50) Placebo ( n = 49)P Value Malignant/benign tumors 31/19 36/13 .223 Easy/difficult to reach 27/23 32/17 .252 Mean size (cm) 4.7 ± 3.3 3.9 ± 2.6 .193 Lesion visibility poor/fair 3/47 2/47 1.000
EMONO, equimolar mixture of oxygen and nitrous oxide.
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Treatments
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Table 3
Information Related to the Analgesic Procedure
Patients EMONO ( n = 50) Placebo ( n = 49)P Value Mean gas flow rate during the procedure (L/min) 9.1 ± 2.6 9.2 ± 2.5 0.912 Mean duration of gas inhalation during the procedure (min) 16.9 ± 9.3 16.1 ± 7.2 0.905 Mean duration of the procedure (min) 10.6 ± 8.7 9.1 ± 6.0 0.842
EMONO, equimolar mixture of oxygen and nitrous oxide.
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Evaluation
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Discussion
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Acknowledgments
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