J. Jakobsson

Effects on the bispectral index during medium‐high dose fentanyl induction with or without propofol supplement

Background: The search for a drug‐independent monitor to determine depth of anaesthesia and hypnosis continues. The bispectral analysis (BIS) of the EEG correlates well with the clinical dose–response of hypnotic drugs during induction, but the effect on BIS of an opiate induction, as for coronary bypass surgery, is not known.

Cerebral state index during anaesthetic induction: a comparative study with propofol or nitrous oxide.

Background:  Confidently predicting the depth of anaesthesia for the individual patient and independently of drug(s) type using EEG‐based monitors has proven difficult. This open, randomized, explorative study of day surgical patients evaluates the ability of the Cerebral State Monitor™ (Danmeter AB, Odense, Denmark) of anaesthetic depth to identify loss of response (LOR) using either propofol or N20 for induction.

Being awake intermittently during propofol-induced hypnosis: a study of BIS, explicit and implicit memory.

Background: Being awake during anaesthesia is a serious complication. An anaesthetic depth monitor must discriminate in real time between wakefulness and unconsciousness. The present study created a period of wakefulness during propofol‐induced hypnosis. Bispectral index (BIS), explicit and implicit memories of the awake period were investigated.

The sevoflurane-sparing effect of nitrous oxide: a clinical study.

Background: We studied the sevoflurane‐sparing effect of nitrous oxide in a prospective randomised study.

Entropy during propofol hypnosis, including an episode of wakefulness.

Depth of anaesthesia has proved to be a complex process to quantify. Monitors based on bispectral analysis of the electroencephalogram and auditory evoked potential have been available, but only recently has a monitor based on entropy become available. This study determined state entropy and response entropy in nine healthy volunteers during propofol hypnosis with a brief intervening period of wakefulness. Both the calculated entropy indices decreased with increasing levels of sedation (r2 = 0.58 and 0.61, respectively) and they showed a high correlation with each other (r2 = 0.94). However, an overlap was observed in real time indices between different stages of the Observers Assessment of Alertness/Sedation Scale. Only three of the nine volunteers had explicit memories from the episode of wakefulness. Electroencephalographic entropy monitors seem to have potential for staging clinical hypnotic effects.

Cost comparison between three different general anaesthetic techniques for elective arthroscopy of the knee.

We compared three anaesthetic techniques for elective knee arthroscopy with special reference to cost‐effectiveness.

Clinical comparison of three different anaesthetic depth monitors during cardiopulmonary bypass.

The lack of a gold standard complicates the evaluation and comparison of anaesthetic depth monitors. This randomised study compares three different depth‐of‐anaesthesia monitors during cardiopulmonary bypass (CPB) at 34 °C with fentanyl/propofol anaesthesia adjusted clinically and blinded to the monitors. Coronary artery bypass grafting patients (n = 21) were randomly assigned to all three possible paired combinations of three monitors: Bispectral Index (Aspect Medical), AAITM auditory evoked potential (Danmeter), EntropyTM (Datex‐Ohmeda). Indices were manually recorded every 5 min during CPB. Agreement between paired indices was classified as good, non‐, or disagreement. Anaesthesia was classed as adequate, inadequate, or excessive according to recommended index values. Of the 255 paired indices recorded, 62% showed good agreement, 33% showed non‐agreement, and 5% showed disagreement. Using good agreement between two monitors as a gold standard, a quarter of the measurements indicate inappropriate anaesthetic depth monitoring during CPB with clinically titrated anaesthetic depth.

Auditory evoked potential monitoring with the AAITM‐index during spinal surgery: decreased desflurane consumption

Background: The auditory evoked potential (AEP) is sensitive to the depth of anesthesia. The A‐line monitor is a novel device that processes the amplitude and latency of the AEP during the mid‐latency time window to provide a simple numerical index, the AAI™‐index. The hypothesis of the present study was that titration of anesthetic depth (desflurane) by means of the AAI™‐index could decrease the consumption of the main anesthetic and shorten emergence times.

The effects of nitrous oxide on the auditory evoked potential index during sevoflurane anaesthesia

Summary We have studied the effects of nitrous oxide on the auditory evoked response index (AAI™‐index) derived from the A‐line monitoring device during sevoflurane anaesthesia in 21 patients undergoing minor ambulatory surgery. During sevoflurane anaesthesia with an AAI™‐index < 30, the addition or withdrawal of nitrous oxide in a concentration of 66% end tidal did not show any linear dose dependent change in AAI™‐index. However, comparing nitrous oxide > 40% to nitrous oxide < 10% end tidal concentration the AAI™‐index did decrease, p < 0.05. The AAI™‐index is either non‐linear at deeper anaesthetic levels or is insensitive to the anaesthetic effects of nitrous oxide in terms of MAC‐multiples.

Is pain prophylaxis in minor gynaecological surgery of clinical value? a double-blind placebo controlled study of paracetamol 1 g versus lornoxicam 8 mg given orally.

Methods: In a prospective randomised placebo controlled double-blind study 210 ASA I-II women scheduled for elective termination of pregnancy received 1 g paracetamol, 8 mg lornoxicam or placebo orally 60 min before anaesthesia which was standardised with propofol, fentanyl and oxygen in nitrous oxide 1:2. Postoperative pain was assessed by VAS-score at 30 and 60 min after end of surgery and at discharge as primary endpoints. Need for rescue medication and time to discharge were secondary endpoints. Results: All patients had an uncomplicated course. Overall pain intensity was low, however, the patients pretreated with lornoxicam had significantly less pain after surgery, no difference could however, be seen in need for rescue medication or time to discharge between the three groups. Conclusion: General pain prophylaxis may be argued in minor gynaecological surgical procedures where postoperative pain is of low intensity. If general prophylaxis is to be given in minor gynaecological surgery, a non steroidal anti-inflammatory (NSAID) such as lornoxicam, seems more efficacious as compared to a standard dose of 1 g paracetamol.