Ketamine for intravenous regional anesthesia

We studied ketamine intravenous regional anesthesia of the upper extremity in volunteers using concentrations of 0.5%, 0.3%, and 0.2%. Ketamine 0.5 and 0.3% produced adequate intravenous regional anesthesia. Anesthesia was inadequate when a 0.2% concentration was used. However, although the 0.3% concentration provides complete sympathetic, sensory, and motor blockade when injected into the isolated extremity, unpleasant psychotomimetic effects after the release of the tourniquet limit the usefulness of this use of ketamine. Ketamine cannot be recommended for intravenous regional anesthesia unless these unpleasant side effects are abolished or controlled by means of pharmacologic adjuvants.     

Dose requirements of pentazocine during abdominal surgery in total intravenous anesthesia using propofol

BACKGROUND: To determine the dose requirements of pentazocine when administered as a single bolus dose in total intravenous anesthesia with propofol for abdominal surgery. METHODS : One hundred and fifty-six patients scheduled for abdominal surgery were analyzed retrospectively. Patients were classified into three groups according to duration of the operation ; under 120 min (Group 1, n=87) ; 120-240 min (Group 2, n=56) ; over 240 min (Group 3, n=13). Anesthesia was induced with propofol using target controlled infusion method, and was maintained with propofol infusion, pentazocine as a single dose before incision, and intermittent administration of vecuronium with 40% oxygen in air. RESULTS: Dosage of pentazocine was significantly increased according to length of the operation. The maintenance doses of propofol were not different among the three groups. Awakening time in about 80% of patients in each group was within 15 minutes. There are no severe complications. CONCLUSIONS : Total intravenous anesthesia with propofol and pentazocine is useful to stabilize hemodynamics and to achieve rapid recovery. For the operation within 120 min, 0.7 mg x kg(-1) of pentazocine is necessary whereas 0.8 mg x kg(-1) of pentazocine is needed in the operation of 120-240 min.     

Influence of intravenous clonidine pretreatment on anesthetic requirements during bispectral EEG-guided sevoflurane anesthesia

STUDY OBJECTIVE: To assess the anesthetic effects of clonidine during sevoflurane anesthesia guided by the bispectral index (BIS), which is a processed EEG variable correlated with anesthetic-hypnotic depth. DESIGN: Placebo-controlled, double-blind clinical trial. SETTINGS: Elective laparoscopic surgery. PATIENTS: 60 ASA physical status I patients scheduled for laparoscopic surgery. INTERVENTIONS: Patients received either clonidine (3 micrograms/kg, 15 min before induction) or placebo premedication for a sevoflurane-induced and sevoflurane-maintained anesthesia. Sevoflurane was titrated against a BIS held between 40 and 50. Analgesia was provided by local infiltration with bupivacaine. Need for postoperative analgesia was recorded. RESULTS AND CONCLUSION: Mean sevoflurane requirements were not lower with clonidine pretreatment. There was statistically better perioperative hemodynamic stability (i.e., fewer episodes of hypertension and tachycardia) without clinical relevance. A decreased need for postoperative analgesia was observed.     

Influence of bispectral index monitoring on fentanyl requirements during total intravenous anesthesia for major gynecological surgery]

OBJECTIVE: To determine the influence that bispectral index (BIS) monitoring of hypnosis might have on need for analgesia during surgery under total intravenous anesthesia provided by bolus administration of fentanyl. PATIENTS AND METHOD: Prospective, randomized and partially double-blind study of 40 patients undergoing major gynecological surgery under total intravenous anesthesia with propofol and fentanyl. In the BIS group (n = 20) propofol administration was adjusted to maintain BIS between 40 and 60. In the control group (n = 20) standard doses were given: 10 mg/kg-1/h-1 after anesthetic induction and for 5 minutes, 8 mg/kg-1/h-1 over the next 5 minutes and 6 mg/kg-1/h-1 throughout the rest of the operation. All patients received intravenous bolus administration of 150 or 75 microg of fentanyl to maintain analgesia whenever systolic blood pressure and heart rate increased 20% over baseline. We compared propofol and fentanyl requirements, intraoperative changes in BIS, and awakening from anesthesia. RESULTS: Patient and surgical characteristics were similar in both groups. BIS monitoring allowed propofol administration to be decreased a mean 24% during maintenance of anesthesia, and this in turn was associated with a significant increase in mean dose of fentanyl (415 microg versus 253 microg in the BIS and control groups, respectively; p = 0.01). Mean values of BIS were higher in the BIS group (46.4 versus 42.2; p = 0.04) and patients in the BIS group awoke sooner (in 7.7 min versus 11.1 min; p = 0.01) and tended to report less pain upon arrival at the postanesthetic recovery room, although the difference was not statistically significant. CONCLUSIONS: BIS monitoring of depth of hypnosis can influence requirements for fentanyl during total intravenous anesthesia by bolus dosing for maintenance of analgesia. This is probably due to changes in the administration of propofol made possible by BIS monitoring.     

A pocket calculator program for intravenous requirements

A program to calculate the 24-h intravenous requirements of water, nitrogen, energy and six electrolytes on a card-programmable pocket calculator is described. Comparison of calculator-generated requirements with intravenous feeding regimens prescribed by junior clinicians for 8 ill patients suggests that the clinicians provide too much water and too little nitrogen and energy. Certain program modifications are necessary to widen the useful clinical application of the calculator, but in general it is a useful bedside tool capable of further application to suitable medical tasks.     

The changes in hemodynamics and dose requirements in total intravenous anesthesia using propofol and buprenorphine

A retrospective study was performed to evaluate the changes in hemodynamics and dose requirements in total intravenous anesthesia (TIVA) using propofol and buprenorphine without (Group S: spinal surgery (3-6 h), n = 8, 28-79 Y) or with (Group A: abdominal surgery (5-10 h), n = 15, 36-83 Y) epidural anesthesia. All patients were premedicated with midazolam i.m. (2-5 mg). Anesthesia was maintained with a single dose of buprenorphine (Group S: 1.9 +/- 0.4 micrograms.kg-1, Group A: 2.0 +/- 0.5 micrograms.kg-1), propofol infusion and vecuronium with 40% oxygen in air. Group A was supplemented with continuous epidural anesthesia using 2% mepivacaine. In Group A, mean arterial pressure (MAP) and heart rate remained stable after the start of surgery. However, in Group S, 2 hours after the start of surgery MAP increased (P < 0.05) and remained elevated (P < 0.05) at higher levels than those in Group A. The maintenance dose of propofol in Group A (4.0 +/- 1.1 mg.kg-1.h-1) was significantly smaller than in Group S (6.5 +/- 0.9 mg.kg-1.h-1). In both groups, infusion rates of propofol were unchanged from 1 hour after the start to the end of surgery. Infusion rates of mepivacaine (5.2 +/- 0.9 ml.h-1) were unchanged following the increase 2 hours after the start of surgery. Awakening times were within 25 min (Group S 11.3 +/- 7.2 min vs Group A 14.7 +/- 7.3 min). There was no awareness during anesthesia in either group. The results suggest that additional continuous epidural anesthesia in TIVA would be useful to reduce propofol dose, to stabilize hemodynamic state and to obtain rapid recovery in anesthesia of long duration.     

Lidocaine-tramadol versus lidocaine-dexmedetomidine for intravenous regional anesthesia

BackgroundIntravenous regional anesthesia (IVRA) has been used for more than a century. Both tramadol (synthetic opioid) and dexmedetomidine (α₂-agonist) can act locally.Aim of the workTo compare effects of adding tramadol versus dexmedetomidine to lidocaine during IVRA.Patients and methodsSixty patients were randomly assigned into: Group C (n = 20), Group T (n = 20), and Group D (n = 20). All patients received 3 mg/kg 0.5% lidocaine [+100 mg tramadol in Group T, or 1 μg/kg dexmedetomidine in Group D]. Times of onset and offset of sensory and motor blocks, and time to tourniquet pain were recorded. Postoperative VAS score, time to first dose, and total amounts of supplementary analgesia (Paracetamol) were recorded. Sedation was evaluated using Ramsay sedation scale (RSS).ResultsSignificantly shorter onset times and longer recovery times of sensory and motor block were recorded in Groups T and D compared to Group C (P < 0.05); while, with no significant differences between Groups T and D. Delayed onset of tourniquet pain occurred in Groups T and D compared to Group C (P < 0.05) with no significant differences between Groups T and D. Fourteen patients required fentanyl to control tourniquet pain in Group C compared to (5 and 4) in Groups T and D respectively. Significantly lower Postoperative VAS score, longer time to first dose and lower consumption of Paracetamol were recorded in Groups T and D than in Group C; with no significant differences between Groups T and D. Complications were skin rash in 30% of patients in Group T, bradycardia and sedation in 35% and 65% of patients in Group D respectively.ConclusionAddition of either tramadol or dexmedetomidine enhances lidocaine during IVRA with higher incidence of skin rash with tramadol and postoperative bradycardia and sedation with dexmedetomidine.     

Locoregional intravenous anesthesia]

OBJECTIVE: To analyse current data on intravenous regional anaesthesia (IVRA), its benefits and drawbacks. DATA SOURCES: Articles were obtained from a Medline search using the following search terms: 'intravenous regional anaesthesia', alone or combined with 'local anaesthetic agents', 'toxicity'. STUDY SELECTION: Following articles in English and in French have been selected: main articles, original articles, update and review articles, letters to the editor and recent editorials. DATA EXTRACTION: Physiopathological and pharmacological data were extracted for involved mechanisms and means for improving this technique. DATA SYNTHESIS: IVRA is a reliable and efficient technique with a lower cost than general anaesthesia and well adapted for limb surgery in the ambulatory patient. Depending on the site of the surgical field, the pneumatic tourniquet is set either on the arm, forearm or wrist for the upper limb or thigh, calf or ankle for the lower limb. When set in periphery, less local anaesthetic agent is required. A wide tourniquet requires a lower inflation pressure than a double cuff tourniquet. A single cuff is as efficient as a dual cuff if shape, size and inflating pressure are appropriate. The limb occlusion pressure (LOP) is the minimal pressure required to occlude blood flow. It is assessed with either a pulse oximeter or Doppler for determination of the lowest cuff inflating pressure. The cuff is inflated to 50 mmHg above LOP. Oozing in the surgical field can be decreased by the re-exsanguination technique. Currently, lidocaine is the only local anaesthetic released in France for IVRA. Addition of a muscle relaxant, a NSAID or clonidine allows the dose of local anaesthetic agent to be decreased and improves postoperative analgesia.