. The tumescent technique for local anesthesia permits regional local anesthesia of the skin and subcutaneous tissues by direct infiltration. The tumescent technique uses large volumes of a dilute anesthetic solution to produce swelling and firmness of targeted areas. This investigation examines the absorption pharmacokinetics of dilute solutions of lidocaine (0.1% or 0.05%) and epinephrine (1:1,000,000) in physiologic saline following infiltration into subcutaneous fat of liposuction surgery patients. Plasma lidocaine concentrations were measured repeatedly over more than 24 hours following the infiltration. Peak plasma lidocaine levels occurred 12–14 hours after beginning the infiltration. Clinical local anesthesia is apparent for up to 18 hours, obviating the need for postoperative analgesia. Dilution of lidocaine diminishes and delays the peak plasma lidocaine concentrations, thereby reducing potential toxicity. Liposuction reduces the total amount of lidocaine absorbed systemically, but does not dramatically reduce peak plasma lidocaine levels. A safe upper limit for lidocaine dosage using the tumescent technique is estimated to be 35 mg/kg. Infiltrating a large volume of dilute epinephrine assures diffusion throughout the entire targeted area while avoiding tachycardia and hypertension. The associated vasoconstriction is so complete that there is virtually no blood loss with liposuction. The tumescent technique can be used with general anesthesia or IV sedation. However, with appropriate instrumentation and surgical method, the tumescent technique permits liposuction of large volumes of fat totally by local anesthesia, without IV sedation or narcotic analgesia.

Tumescent technique for regional anesthesia permits lidocaine doses of 35 mg/kg for liposuction.

Background: Intravenous infusion of lidocaine decreases postoperative pain and speeds the return of bowel function. The authors therefore tested the hypothesis that perioperative lidocaine infusion facilitates acute rehabilitation protocol in patients undergoing laparoscopic colectomy. Methods: Forty patients scheduled to undergo laparoscopic colectomy were randomly allocated to receive intravenous lidocaine (bolus injection of 1.5 mg/kg lidocaine at induction of anesthesia, then a continuous infusion of 2 mg kg 1 h 1 intraoperatively and 1.33 mg kg 1 h 1 for 24 h postoperatively) or an equal volume of saline. All patients received similar intensive postoperative rehabilitation. Postoperative pain scores, opioid consumption, and fatigue scores were measured. Times to first flatus, defecation, and hospital discharge were recorded. Postoperative endocrine (cortisol and catecholamines) and metabolic (leukocytes, C-reactive protein, and glucose) responses were measured for 48 h. Data (presented as median [25‐75% interquartile range], lidocaine vs. saline groups) were analyzed using Mann‐Whitney tests. P < 0.05 was considered statistically significant. Results: Patient demographics were similar in the two groups. Times to first flatus (17 [11‐24] vs. 28 [25‐33] h; P < 0.001), defecation (28 [24‐37] vs. 51 [41‐70] h; P 0.001), and hospital discharge (2 [2‐3] vs. 3 [3‐4] days; P 0.001) were significantly shorter in patients who received lidocaine. Lidocaine significantly reduced opioid consumption (8 [5‐18] vs. 22 [14‐36] mg; P 0.005) and postoperative pain and fatigue scores. In contrast, endocrine and metabolic responses were similar in the two groups. Conclusions: Intravenous lidocaine improves postoperative analgesia, fatigue, and bowel function after laparoscopic colectomy. These benefits are associated with a significant reduction in hospital stay.

Intravenous lidocaine infusion facilitates acute rehabilitation after laparoscopic colectomy.

Studies using molecular modeling, genetic engineering, neurophysiology/pharmacology, and whole animals have advanced our understanding of where and how inhaled anesthetics act to produce immobility (minimum alveolar anesthetic concentration; MAC) by actions on the spinal cord. Numerous ligand- and voltage-gated channels might plausibly mediate MAC, and specific amino acid sites in certain receptors present likely candidates for mediation. However, in vivo studies to date suggest that several channels or receptors may not be mediators (e.g., gamma-aminobutyric acid A, acetylcholine, potassium, 5-hydroxytryptamine-3, opioids, and alpha(2)-adrenergic), whereas other receptors/channels (e.g., glycine, N-methyl-D-aspartate, and sodium) remain credible candidates.

Inhaled anesthetics and immobility: Mechanisms, mysteries, and minimum alveolar anesthetic concentration

Postoperative ileus is a concern among surgical patients.Epidural anesthesia and analgesia with local anesthetics can decrease the duration of ileus. Significant systemic absorption of local anesthesia occurs during epidural use. In this study, we examined whether many of the beneficial effects on b

Intravenous lidocaine speeds the return of bowel function, decreases postoperative pain, and shortens hospital stay in patients undergoing radical retropubic prostatectomy

Controlling the hemodynamic response to laryngoscopy and endotracheal intubation

The effects of various plasma concentrations of lidocaine on nitrous oxide anesthesia in man and halothane requirements in the dog were studied The response to incision of the skin was observed in 20 patients who were anesthetized with nitrous oxide, 70% inspired, and oxygen, 30%, plus various plasma levels of lidocaine In addition, changes in the MAC of halothane in dogs were observed at various levels of lidocaine In both circumstances lidocaine concentrations of 3 to 6 microgram/ml decreased anesthetic requirements approximately 10 to 28% At clinically common concentrations of lidocaine, significant decreases in anesthetic requirements should be anticipated

Effects of Lidocaine on the Anesthetic Requirements for Nitrous Oxide and Halothane

The effects of various plasma concentrations of lidocaine on nitrous oxide anesthesia in man and halothane requirements in the dog were studied. The response to incision of the skin was observed in 20 patients who were anesthetized with nitrous oxide, 70% inspired, and oxygen, 30%, plus various plasma levels of lidocaine. In addition, changes in the MAC of halothane in dogs were observed at various levels of lidocaine. In both circumstances lidocaine concentrations of 3 to 6 microgram/ml decreased anesthetic requirements approximately 10 to 28%. At clinically common concentrations of lidocaine, significant decreases in anesthetic requirements should be anticipated.

Effects of lidocaine on the anesthetic requirements for nitrous oxide and halothane

Arterial plasma lidocaine concentration of 1 to 3.5 microgram/ml produced dose-related decreases in enflurane requirement (MAC) ranging from 15 to 37 per cent in dogs. The ventilatory responses to carbon dioxide at comparable depths of anesthesia with enflurane alone and the enflurane-lidocaine combination were measured in each animal and compared. With both anesthetic regimens there were increases in resting arterial carbon dioxide tension (mean maximal increase = 18 torr) and a 69 per cent decrease in the slope of the ventilatory response as depth of anesthesia increased. The effect of the drug interaction appears to be additive, since the ventilatory depression produced by the enflurane-lidocaine combination was no greater than that produced by enflurane alone at equivalent levels of anesthesia.

Richard S. Himes

Papers

Effects of Lidocaine on the Anesthetic Requirements for Nitrous Oxide and Halothane

Effects of lidocaine on the anesthetic requirements for nitrous oxide and halothane

Enflurane Requirement and Ventilatory Response to Carbon Dioxide during Lidocaine Infusion in Dogs