Isabelle Negre

Patient-administered nitrous oxide/oxygen inhalation provides safe and effective analgesia for percutaneous liver biopsy: A randomized placebo-controlled trial

OBJECTIVE:Although percutaneous liver biopsy (PLB) can be a painful procedure, common practice has not included intravenous sedation or analgesia Patient-administered nitrous oxide/oxygen (N2O/O2) inhalation has demonstrated analgesic efficacy in various procedures associated with mild to moderate pain The aim of this study was to investigate the safety and efficacy of analgesia with N2O/O2 inhalation for PLBMETHODS:One hundred consecutive patients undergoing a first PLB (for chronic hepatitis C: 56, for alcoholic liver disease: 23, for miscellaneous reasons: 21) Patients were randomly assigned to self-administrate from a facial mask with a demand valve, for 5 min before and during biopsy, either a breathing mixture of 50% N2O/O2 (N2O group, n = 51), or a breathing oxygen placebo (P group, n = 49) Liver biopsy was performed at bedside after adequate local anesthesia with xylocaine At the end of the procedure, patients were asked to self-evaluate pain experienced using a visual analogue scale (VAS) with scoring from 0 to 100 mm.RESULTS:N2O/O2 administration resulted in the absence of pain in a significantly higher number of patients treated than in patients of the P group: 19 versus 2, respectively (p = 0.0001). Patients receiving N2O/O2 had significantly lower pain scores than those of the P group: 12 ± 12 versus 28 ± 19 mm (p < 0.0001). No serious complication was observed. Side effects of N2O/O2 were minor and reversible. The average cost per biopsy was 4 US dollars.CONCLUSIONS:Patient-administered N2O/O2 inhalation provides safe and effective analgesia, at a reasonable cost, for PLB. Its routine use could be useful for the management of patients with chronic liver disease undergoing PLB as it may enhance patients compliance with future biopsies.

Ventilatory response to carbon dioxide after intramuscular and epidural fentanyl

: The authors compared the effects of administration of fentanyl 200 micrograms on the ventilatory response to carbon dioxide in two groups of nine healthy unpremedicated subjects: one group received fentanyl as an intramuscular injection; in the other group, fentanyl was injected into the epidural space. In the intramuscular group, the slope of the ventilatory response to CO2 did not decrease significantly. In the epidural group, the slope of the ventilatory response to CO2 decreased significantly from 2.48 +/- 1.05 to 1.77 +/- 0.7, 1.74 +/- 0.7, and 2.07 +/- 0.74 L X min-1 X mm Hg-1 at 30, 60, and 120 min after injection (chi +/- SD, P less than or equal to 0.05), respectively. At each time of the study, plasma fentanyl levels were significantly lower in the epidural group than in the intramuscular group (P less than or equal to 0.05). These results suggest that epidural fentanyl induces a nonsystemic ventilatory depression that may be due to the rostral spread of the drug.

Preoperative analgesia with epidural morphine

In a prospective double-blind study, we examined the effects of preoperative epidural morphine associated with general anesthesia (GA) on intra- and postoperative analgesic requirements over a 3-day postoperative period. Twenty patients scheduled for major intraabdominal surgery were randomly assigned to two groups: a control group (n = 10) and an epidural group (n = 10) which received an epidural injection of 5 mg of preservative-free morphine in 10 mL of 0.9% saline. Afterward, both groups received the same GA. Postoperative pain relief was achieved with intravenous (IV) boluses of morphine using a patient-controlled analgesia device. We found smaller opioid requirements in the epidural group than in the control group for intraoperative fentanyl (465 +/- 179 micrograms vs 983 +/- 682 micrograms), for postoperative morphine at 12 h (3.1 +/- 3 mg vs 21.4 +/- 13.8 mg) and 24 h (9.1 +/- 6.4 mg vs 20.6 +/- 9.8 mg), and for the cumulated needs over the 3-day postoperative period (37 +/- 24 mg vs 86 +/- 42 mg). The consumption of IV morphine by the control group decreased over time (P < 0.001, r = 0.44), whereas, in the epidural group, consumption remained constant and small during the 3 days. The maximum pain score was significantly lower in the epidural group than in the control group at 24 h (0.65 +/- 2.4 vs 3 +/- 2), at 36 h (0.3 +/- 0.6 vs 3 +/- 2.7), and at 60 h (0.1 +/- 0.3 vs 1.8 +/- 1.2) after surgery. These results suggest that a single epidural injection of 5 mg of morphine before major surgery produces intra- and postoperative pain relief for at least 3 days.

Ventilatory Response to Carbon Dioxide after Intra muscular and Epidural Fentanyl

The authors compared the effects of administration of fentanyl 200 μg on the Ventilatory response to carbon dioxide in two groups of nine healthy unpremedicated subjects: one group received fentanyl as an intramuscular injection; in the other group, fentanyl was injected into the epidural space. In the intra muscular group, the slope of the venti-latory response to CO2 did not decrease significantly. In the epidural group, the slope of the Ventilatory response to CO2 decreased significantly from 2.48 ± 1.05 to 1.77 ± 0.7, 1.74 ± 0.7, and 2.07 ± 0.74 L·min-1·mm Hg−1 at 30, 60, and 120 min after injection (x ± SD, P ≤ 0.05), respectively. At each time of the study, plasma fentanyl levels were significantly lower in the epidural group than in the intramuscular group (P ≤ 0.05). These results suggest that epidural fentanyl induces a non systemic Ventilatory depression that may be due to the rostral spread of the drug.

Analgesia and Ventilatory Response to Carbon Dioxide after Intramuscular and Epidural Alfentanil

The analgesic and ventilatory depressant effects of epidural and intramuscular alfentanil (15 μg/kg) were compared in two groups of seven healthy unpremedicated subjects. Fifteen minutes after IM injection, the slope of the ventilatory response to CO2 decreased significantly (from 2.72 ± 0.34 to 1.8 ± 0.20 L·min−1·mm Hg−1) while assessment of periosteal analgesia showed no change. After epidural injection, the slope of the ventilatory response to CO2 decreased significantly (from 2.32 ± 0.42 to 1.61 ± 0.29, 1.51 ± 0.29, and 1.53 ± 0.21 L ·min−1 ·mm Hg−1) at 15,45, and 90 minutes (x ± SD, P < 0.05), and there was significant periosteal analgesia of the tibia (15 and 30 minutes after injection) and of the radius (30 to 90 minutes after injection). Throughout the study, plasma alfentanil levels were similar after intramuscular and epidural injection. These results suggest that epidural alfentanil induces ventilatory depressiondue to the rostral spread of the drug rather than to systemic absorption.

Ventilatory Response to CO2 Following Axillary Blockade with Bupivacaine

The systemic effect of bupivacaine on the control of ventilation was studied in eight ASA I (six male, two female) unpremedicated healthy subjects aged 30–55 yr (mean 43.5 yr) and weighing 59–82 kg (mean 69 kg) after axillary blockade with bupivacaine 0.5% without epinephrine, 3 mg/kg. The slope of the ventilatory response to CO2 was significantly increased (P < 0.05) from its control value (1.77 ± 1.03 1 ± min−1 · mmHg−1 [mean ± SD]) 30 min (+19 ± 32%) and 60 min (+32 ± 37%) after axillary blockade, while plasma bupivacaine levels were 1.65 ± 0.82 and 1.40 ± 0.60 μg/ml, respectively. The correlation between individual plasma bupivacaine levels and the changes in the slope of the ventilatory response to CO2 was significant (r = 0.57, n = 16, P < 0.05). Resting minute ventilation and end-tidal CO2 values did not change significantly. These results suggest that bupivacaine has a systemic stimulating effect on the ventilatory control mechanisms.

Ventilatory Response to Carbon Dioxide After Intramuscular and Epidural Fentanyl

The authors compared the effects of administration of fentanyl 200 μg on the Ventilatory response to carbon dioxide in two groups of nine healthy unpremedicated subjects: one group received fentanyl as an intramuscular injection; in the other group, fentanyl was injected into the epidural space. In the intra muscular group, the slope of the venti-latory response to CO2 did not decrease significantly. In the epidural group, the slope of the Ventilatory response to CO2 decreased significantly from 2.48 ± 1.05 to 1.77 ± 0.7, 1.74 ± 0.7, and 2.07 ± 0.74 L·min-1·mm Hg−1 at 30, 60, and 120 min after injection (x ± SD, P ≤ 0.05), respectively. At each time of the study, plasma fentanyl levels were significantly lower in the epidural group than in the intramuscular group (P ≤ 0.05). These results suggest that epidural fentanyl induces a non systemic Ventilatory depression that may be due to the rostral spread of the drug.