Regular tramadol use does not affect the propofol dose requirement for induction of anaesthesia

Do we have today a reliable method to detect the moment of loss of consciousness during induction of general anaesthesia?

This review aims to give an overview of the current state of monitoring depth of anaesthesia and detecting the moment of loss of consciousness, from the first clinical signs involved in anaesthesia to the latest technologies used in this area. Such techniques are extremely important for the development of automatic systems for anaesthesia control, including preventing intraoperative awareness episodes and overdoses. A search in the databases Pubmed and IEEE Xplore was performed using terms such anaesthetic monitoring, depth of anaesthesia, loss of consciousness, as well as anaesthesia indexes, namely BIS. Despite the several methods capable of monitoring the hypnotic state of anaesthesia, there is still no methodology to accurate detect the moment of loss of consciousness during induction of general anaesthesia.

Anaesthetic interventions for prevention of awareness during surgery

BACKGROUND

General anaesthesia is usually associated with unconsciousness. 'Awareness' is when patients have postoperative recall of events or experiences during surgery. 'Wakefulness' is when patients become conscious during surgery, but have no postoperative recollection of the period of consciousness.

OBJECTIVES

To evaluate the efficacy of two types of anaesthetic interventions in reducing clinically significant awareness:- anaesthetic drug regimens; and- intraoperative anaesthetic depth monitors.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, ISSUE 4 2016); PubMed from 1950 to April 2016; MEDLINE from 1950 to April 2016; and Embase from 1980 to April 2016. We contacted experts to identify additional studies. We performed a handsearch of the citations in the review. We did not search trial registries.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of either anaesthetic regimens or anaesthetic depth monitors. We excluded volunteer studies, studies of patients prior to skin incision, intensive care unit studies, and studies that only randomized different word presentations for memory tests (not anaesthetic interventions).Anaesthetic drug regimens included studies of induction or maintenance, or both. Anaesthetic depth monitors included the Bispectral Index monitor, M-Entropy, Narcotrend monitor, cerebral function monitor, cerebral state monitor, patient state index, and lower oesophageal contractility monitor. The use of anaesthetic depth monitors allows the titration of anaesthetic drugs to maintain unconsciousness.

DATA COLLECTION AND ANALYSIS

At least two authors independently scanned abstracts, extracted data from the studies, and evaluated studies for risk of bias. We made attempts to contact all authors for additional clarification. We performed meta-analysis statistics in packages of the R language.

MAIN RESULTS

We included 160 studies with 54,109 enrolled participants; 53,713 participants started the studies and 50,034 completed the studies or data analysis (or both). We could not use 115 RCTs in meta-analytic comparisons because they had zero awareness events. We did not merge 27 of the remaining 45 studies because they had excessive clinical and methodological heterogeneity. We pooled the remaining 18 eligible RCTs in meta-analysis. There are 10 studies awaiting classification which we will process when we update the review.The meta-analyses included 18 trials with 36,034 participants. In the analysis of anaesthetic depth monitoring (either Bispectral Index or M-entropy) versus standard clinical and electronic monitoring, there were nine trials with 34,744 participants. The overall event rate was 0.5%. The effect favoured neither anaesthetic depth monitoring nor standard clinical and electronic monitoring, with little precision in the odds ratio (OR) estimate (OR 0.98, 95% confidence interval (CI) 0.59 to 1.62).In a five-study subset of Bispectral Index monitoring versus standard clinical and electronic monitoring, with 34,181 participants, 503 participants gave awareness reports to a blinded, expert panel who adjudicated or judged the outcome for each patient after reviewing the questionnaires: no awareness, possible awareness, or definite awareness. Experts judged 351 patient awareness reports to have no awareness, 87 to have possible awareness, and 65 to have definite awareness. The effect size favoured neither Bispectral Index monitoring nor standard clinical and electronic monitoring, with little precision in the OR estimate for the combination of definite and possible awareness (OR 0.96, 95% CI 0.35 to 2.65). The effect size favoured Bispectral Index monitoring for definite awareness, but with little precision in the OR estimate (OR 0.60, 95% CI 0.13 to 2.75).We performed three smaller meta-analyses of anaesthetic drugs. There were nine studies with 1290 participants. Wakefulness was reduced by ketamine and etomidate compared to thiopental. Wakefulness was more frequent than awareness. Benzodiazepines reduces awareness compared to thiopental, ketamine, and placebo., Also, higher doses of inhaled anaesthetics versus lower doses reduced the risk of awareness.We graded the quality of the evidence as low or very low in the 'Summary of findings' tables for the five comparisons.Most of the secondary outcomes in this review were not reported in the included RCTs.

AUTHORS' CONCLUSIONS

Anaesthetic depth monitors may have similar effects to standard clinical and electrical monitoring on the risk of awareness during surgery. In older studies comparing anaesthetics in a smaller portion of the patient sample, wakefulness occurred more frequently than awareness. Use of etomidate and ketamine lowered the risk of wakefulness compared to thiopental. Benzodiazepines compared to thiopental and ketamine, or higher doses of inhaled anaesthetics versus lower doses, reduced the risk of awareness.

A comparison of levobupivacaine and levobupivacaine-tramadol combination in bilateral infraorbital nerve block for postoperative analgesia after nasal surgery

BACKGROUND

Our aim in this study was to investigate the effect of levobupivacaine and a levobupivacaine + tramadol combination on postoperative analgesia in intraoperative nerve block under standard general anesthetic.

METHODS

Forty-five patients undergoing outpatient nasal surgery under general anesthesia were randomized into 3 groups. Group L: 0.25% levobupivacaine, group T: 0.25% levobupivacaine and 50 mg tramadol, group S: normal saline solution; 2 mL of each being injected into the infraorbital foramen. Intraoperative hemodynamic changes were recorded. Verbal numeric rating scale (NRS) values were checked at 30 minutes and 1, 2, 8, and 12 hours postoperatively, and the need for rescue analgesic treatment in the first 12 hours of all patients was recorded. Also antiemetic drug requirement and side effects (nausea, edema, erythema, hematoma, and sedation) were recorded.

RESULTS

At 30 minutes and 1 hour postoperatively, NRS pain scores were lower in group T than in group S (P < 0.0001, P = 0.01, respectively). NRS pain score was lower in group T compared with group L at 1 hour postoperatively (P = 0.01). Effective analgesia time (sec) in the control group (142.67 ± 77.31) was shorter than levobupivacaine (240 ± 96.39) and levobupivacaine added to tramadol groups (277 ± 11.60) (P < 0.05). Additional analgesic requirement in the control group was higher than the other 2 groups in early postoperative period (P < 0.05).

CONCLUSIONS

Bilateral infraorbital nerve block with 0.25% levobupivacaine is an effective, reliable, and simple technique in the treatment of postoperative pain in nasal surgery. In addition, the addition of tramadol as an adjuvant to local anesthetics in this technique is safe.

Tramadol use for axillary brachial plexus blockade

BACKGROUND

We investigated the effects of tramadol added to the mixture of local anesthetic for axillary brachial plexus blockade (ABB) in patients to have undergone hand and forearm surgery.

MATERIALS AND METHODS

Forty patients from the ASA classification I and II, between 18 and 60 y of age, were included in this randomized double-blind study. Group C: levobupivacaine (150 mg) + lidocaine (200 mg) (n = 20), Group T: levobupivacaine (150 mg), + lidocaine (200 mg) + tramadol (100 mg) (n = 20). Intravenous midazolam of 0.02 mg/kg was given for premedication. ABB was performed with 42 mL mixture of local anesthetic, using peripheral nerve stimulator. The duration of onset of motor and sensory blockades was recorded. The postoperative first analgesic need, sedation, and satisfaction score and side effects were recorded.

RESULTS

There was no significant difference between the groups regarding intraoperative visual analog scale (VAS), hemodynamics, adverse effects, sedative and analgesic requirement, and the patient satisfaction. The development of motor block at the median nerve on the 5th min (P = 0.03) and at the ulnar nerve on 10th and 15th min in Group T were (P = 0.01, P = 0.03, respectively) considerably longer than that in Group C.

CONCLUSIONS

Adding 100 mg of tramadol to the combination of levobupivacaine and lidocaine during ABB could not provide an important clinical effect in patients undergoing hand and forearm surgery.