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Biomedical subjects

M Enlund

Publications and source records attributed to M Enlund.

18 recordsLinked to original sources
PubMed2003

Ceasing routine use of nitrous oxide-a follow up.

BACKGROUND: The role of nitrous oxide in modern anaesthesia is questioned. The routine use of nitrous oxide was almost completely stopped in our department after November 1, 2000, and we now report some consequences. METHODS: Staff completed a questionnaire after 6 months, and we analysed the use of hypnotics and opioids after 12 months. The cost of drugs for the year after stopping nitrous oxide was compared with the cost 2 yr before. RESULTS: Less than half of the 55 staff members who answered the questionnaire used nitrous oxide in the 6 months after the stop, and they did so on only a few occasions. Half of the staff members thought the benefit of nitrous oxide was small. Most supported the change. The use of opioids was stable during the study period, and there was an annual increase of 12-14% in the use of hypnotics during the 3 yr. CONCLUSIONS: The staff questionnaire showed a strong acceptance of the new policy, and the use of other anaesthetic agents did not increase as expected. Has the value of nitrous oxide been overestimated?

Analgesics, Opioid↗
PubMed2002

Intraoperative awareness: detected by the structured Brice interview?

BACKGROUND: Awareness is a rare complication in general anesthesia, but its consequences are stressful. Efforts must be undertaken to prevent, diagnose, and, if occurring, treat it. The incidence of awareness is higher following anesthesia involving the use of muscle relaxants. As a part of a quality assurance program at our short-stay surgery all patients exposed to general anesthesia are routinely subjected to a Brice interview, which aims to evaluate our standard anesthetic technique regarding awareness. METHODS: The Brice interview was used prospectively in 5216 patients given a propofol/opioid anesthetic for day-case or short-stay surgery. Neuromuscular blocks were used only for surgical needs, not routinely. All patients were interviewed on discharge from the recovery room. A second interview, according to Brice, was undertaken by telephone 3-7 days later in the case of a notable intraoperative event, or otherwise after postoperative patient complaints. All patients were also interviewed by telephone 1-2 days postoperatively. RESULTS: None of the patient interviews indicated awareness. This was also the case in five non-relaxed patients who had an incident of light anesthesia with eye opening and gross motor response without forewarning. Neuromuscular blockade was used in 7% of patients. DISCUSSION: We were unable to detect intraoperative awareness. The anesthetic regimen, including minimal use of muscle relaxants, might be beneficial for awareness prevention. Alternatively, the diagnostic power, the timing of the Brice interview, or the number of interviews performed may be questioned.

Adolescent↗
PubMed2002

The sevoflurane saving capacity of a new anaesthetic agent conserving device compared with a low flow circle system.

BACKGROUND: An anaesthetic agent conserving device (ACD) has been added to a Bain system to approach the agent-saving capacity of a low flow circle system. METHODS: Randomly selected ASA physical status I patients received a standardized anaesthetic with sevoflurane in air/O2 through either a circle system with 1.5 l/min fresh gas flow (n = 8), or through a Bain system with an added ACD with fresh gas flow 4.4-6.4 l/min (n = 8). A target controlled infusion of remifentanil was used for analgesia. RESULTS: The median sevoflurane consumption was 19.7 and 22.0 ml/MAC/h with the low flow circle system and the Bain system + ACD, respectively (P=0.10, Mann-Whitney U-test), or when adjusted for weight 0.25 and 0.28 ml/MAC/h/kg (P=0.26, Mann-Whitney U-test). CONCLUSION: The expenditure of sevoflurane with a Bain system + ACD was close to that in a circle system with 1.5 l/min fresh gas flow. It is thereby possible to use sevoflurane to all its potential, performing for example rapid alterations in end-tidal concentration using high fresh gas flows by combining a Bain system with an ACD. Although the price is not decided for this not yet commercially available device, a potential for a lower cost exists. Additionally, there will be no concerns of toxic compounds produced in the absorber.

Adult↗
PubMed2001

Unintentional hypotension from lidocaine infiltration during orthognathic surgery and general anaesthesia.

BACKGROUND: A probable causal relationship between submucosal infiltration of lidocaine, with adrenaline 12.5 microg x mL(-1), and untoward arterial hypotension during general anaesthesia for orthognathic surgery was investigated in two parts. METHODS: The first part of the study was open and non-randomised. The patients served as their own controls, receiving 5.4 mL saline/adrenaline before mandibular or maxillary surgery on the first side of the jaw and 5.4 mL lidocaine (2%)/adrenaline on the other side a minimum of 40 min later. Nine patients received in total 11 pairs of injections of the study drugs. In Part Two, 50 mg or 100 mg of lidocaine with adrenaline was infiltrated in an observer-blinded and randomised order in either side of the jaw in another 13 patients. RESULTS: A significant and dose-dependent blood pressure decrease was observed after infiltration of lidocaine/adrenaline, but not after saline/adrenaline. The heart rate increased significantly after both types of injections, most pronounced after saline/adrenaline. Mean arterial blood pressure decreased on average 11% and 23% with lidocaine 50 mg and 100 mg, respectively (P<0.05, ANOVA). CONCLUSION: Lidocaine induced dose-dependent arterial hypotension when combined with a defined level of general anaesthesia. The causative mechanism is unclear.

Adolescent↗
PubMed2001

The Combitube for failed intubation--instructions for use.

The Combitube is easy to use, but it might be years between occasions for use, and most likely the situation is stressful. Then, normal routines might be forgotten. We illustrate that the Combitube instructions would be improved by including a recommendation of cuff pressure monitoring.

Female↗
PubMed2001

A new device to reduce the consumption of a halogenated anaesthetic agent.

We report the first clinical application of a new anaesthetic agent-saving device. The principles of a heat-moisture exchanger have been further developed to create a device that reduces inhalational agent consumption. Sixteen patients were randomly allocated to receive isoflurane through either a vaporiser or through the agent-saving device. A coaxial Mapleson D system (Bain) was used in both groups. A standard ventilatory setting was used, aiming for normocapnia. Mean (SD) isoflurane consumption was 24.5 (2.8) ml x MAC-hour(-1) with the vaporiser, compared with 15.2 (3.0) ml x MAC-hour(-1) with the new device (p < 0.05). This corresponded to a 40% saving in the consumption of isoflurane. The amount of isoflurane that was scavenged to the atmosphere was reduced by an average of 55%.

Adult↗
PubMed1998

[Dosage of anesthetics--a tricky question].

The optimal dosage of anaesthetic agents may be difficult. Not only does the intensity of surgical stimuli vary during a surgical procedure, but drug sensitivity varies between subjects exposed to comparable stimuli. Moreover, clinically monitored body reactions do not always reflect the balance between central nervous system effects of the surgical stimuli and of the anaesthetic agent. Therefore, the specialist in anaesthesiology requires access to additional methods of monitoring to enable dosage to be optimised for each patient, minute by minute, thus improving the chances of maintaining an appropriate depth of anaesthesia. Two electro-encephalographic techniques are presented in the article, and aspects of under- and over-dosage of anaesthetic agents are discussed.

Anesthetics, General↗
PubMed1998

Evidence of cerebral dysfunction associated with isoflurane- or propofol based anaesthesia for orthognathic surgery, as assessed by biochemical and neuropsychological methods.

A relationship has previously been described between individual mean isoflurane concentrations and the release of a marker of neuronal injury, adenylate kinase (AK), into the cerebrospinal fluid (CSF) after anaesthesia and orthognathic surgery. Likewise, reduced mental performance has been detected. Twenty-nine patients scheduled for orthognathic surgery were assigned to isoflurane- or propofol based anaesthesia, which was adjusted to a defined level with the aid of processed EEG and quantitative surface EMG. In the case of a mean arterial pressure (MAP) < 50 mmHg a phenylephrine infusion was started to keep the MAP above the minimal level, otherwise no regard was paid to the blood pressure, which never exceeded normal values. A lumbar puncture for CSF sampling was performed approximately 20 h postoperatively. The CSF sample was analysed for AK activity. Neuropsychological tests were performed the day prior to surgery and again in the period 4-8 weeks postoperatively. Five patients were re-examined by psychometry 12-30 months later. A release of AK into CSF was confirmed, equal in both groups. Correlation with the anaesthetic dose given was poor. Five patients from each group failed significantly in the postoperative neuropsychological tests. They differed in several demographic respects from the others. When five of the failed patients were re-examined 12-30 months later, three patients still performed poorly in the tests. Biochemical and neuropsychological disturbances were recorded in several patients objected to orthognathic surgery. The underlying mechanisms are unclear, including the role of the anaesthetic drugs or surgery itself.

Adenylate Kinase↗
PubMed1997

Cerebral normoxia in the rhesus monkey during isoflurane- or propofol-induced hypotension and hypocapnia, despite disparate blood-flow patterns. A positron emission tomography study.

BACKGROUND: Due to a few reports of cerebral dysfunction in connection with isoflurane-induced hypotension and concomitant hypocapnia, positron emission tomography (PET) was used to measure cerebral oxygenation and blood flow during similar conditions with isoflurane or propofol. METHODS: The short-lived radionuclide 15O was used for measurement of cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF) and oxygen extraction ratio (OER) regionally in rhesus monkeys during normotensive/normocapnic and hypotensive/hypocapnic conditions, mean arterial pressure 100-110 and 50-65 mmHg and PaCO2 4.4-5.4 and 3.4-4.4 kPa, respectively. Isoflurane or propofol anaesthesia was given (n = 4 in both groups), supported with 70% nitrous oxide and preceded by ketamine anaesthesia (baseline). RESULTS: PET revealed wide variations in CBF between regions during isoflurane anaesthesia, particularly in comparison with propofol anaesthesia, while rCMRO2 decreased globally in a dose-dependent manner during both isoflurane and propofol anaesthesia. The metabolism-flow coupling was intact during propofol but not during isoflurane anaesthesia. Hypotension reduced rCBF, and rOER increased globally with both study drugs when changing from normo- to hypotension. However, this rOER increase was not significant when using PaCO2 as a covariate, and rOER was never above an arbitrary limit for hypoxia of 70%. Thus, hypocapnia, rather than hypotension, was responsible for the somewhat higher rOER measured. CONCLUSION: PET indicated adequate cerebral oxygenation during isoflurane and propofol anaesthesia, despite disparate blood-flow patterns. Hypotension and concomitant moderate hyperventilation reduced rCBF, but did not result in hypoxia.

Anesthesia↗
PubMed1996

A cost-benefit evaluation of using propofol and alfentanil for a short gynecological procedure.

It is well established that the immediate recovery after propofol or alfentanil anesthesia is short. Although the drugs themselves are more expensive than older drugs, a potential for saving costs arises. Concerning the benefits in terms of late recovery, less information is available. With vaginal termination of pregnancy (VTP), anesthesia is supposed to be the major cause of sick-leave. Does propofol and alfentanil anesthesia for VTP reduce sick-leave compared with thiopental and nitrous oxide anesthesia, and do the increased costs of the drugs outweigh the reduced costs of sick-leave? Data were obtained from 39 of 40 patients in ASA class I accepted for VTP and allocated to either propofol and alfentanil anesthesia (PA) or thiopental and nitrous oxide anesthesia (TN). A questionnaire was filled in by the patients at home after regaining full fitness. The number of patients with a sick-leave of 2 days or less in the groups was compared statistically with the number of patients with 3 days or more off work. The economic impact from the reported sick-leave was calculated for each study group, using data from national statistics. The figures were compared with the calculated costs of the drugs. The median number of days of sick-leave was 1 in the PA-group and 2 in the TN-group (range 0-3 and 0-5, respectively). Nineteen of the 20 patients in the PA-group and 13 of the 19 patients in the TN-group needed a short sick-leave period of 2 days or less (one-sided test of proportions, P < 0.05). At the time of the study each patient was paid 210 SEK/day from the social insurance system and the mean cost of the drugs was 72 and 15 SEK/patient in the PA- and TN-groups, respectively. Using the mean difference in sick-leave between the groups of 0.8 days/patient (rather than the difference in median values of 1), a net gain of 111 SEK/patient was the result of changing from thiopental-nitrous oxide anesthesia to propofol-alfentanil anesthesia. Although the cost of drugs was higher, costs for the social insurance system and for the individuals themselves were reduced by almost 50%, when using the propofol and alfentanil combination, resulting in an overall benefit corresponding to almost twice the increase in the cost of anesthesia.

Abortion, Induced↗
PubMed1996

Occurrence of adenylate kinase in cerebrospinal fluid after isoflurane anaesthesia and orthognathic surgery.

UNLABELLED: The study objective was, firstly, to investigate whether anaesthesia with induced arterial hypotension would cause leakage of a biochemical marker of neuronal injury, adenylate kinase (AK), into the cerebrospinal fluid (CSF). ( DEFINITION: arterial hypotension = mean arterial pressure (MAP) 50-65 mmHg during > or = 10 min). Secondly, a subgroup of patients was examined with a limited battery of psychometric tests. Patients, scheduled for orthognathic surgery, were allocated to either hypotension (n = 20) or normotension (n = 20). Seventeen patients were subjected to psychometry. Arterial blood pressure was recorded continuously and controlled by adjustments of the administered concentration of the inhalational anaesthetic isoflurane. Fentanyl, an opioid, was given equally in both groups. A lumbar puncture was performed approximately 20 h post-operatively for a CSF sample, later analysed for AK activity. Neuropsychological tests were performed the day before surgery and the fourteenth day postoperatively. The CSF-AK value was pathologically increased ( > 0.040 U/L) in 24 patients (65%), of whom 9 were normotensive. There was no significant difference between the CSF-AK values in the hypotensive and normotensive groups, mean values were 0.082 (s.d. 0.051) and 0.066 (s.d. 0.059) U/L, respectively. The overall correlation between the 10 min MAP levels and the CSF-AK values was close to zero. In the pilot neuropsychological investigation some abnormalities were observed, indicating clinically significant adverse effects in four hypotensive patients, of whom two displayed pathologically increased CSF-AK values. At the group level, the correlation between the changes in psychometry and the measured CSF-AK values was poor. Increases in CSF-AK activities may be a non-specific occurrence in the perioperative interval, possibly indicating an adverse effect on the brain. Arterial hypotension could not be proven to explain the CSF-AK outcome.

Adenylate Kinase↗
PubMed1989

Adverse effects on the brain in connection with isoflurane-induced hypotensive anaesthesia.

As a marker of brain cell injury, adenylate kinase (AK) was measured in cerebrospinal fluid (CSF) in 10 patients given anaesthesia with isoflurane-induced hypotension for corrective surgery of dentofacial deformities. Nine out of 10 patients displayed a marked increase in CSF-AK postoperatively compared with preoperative values. The postoperative mean value displayed a 400% increase compared to the corresponding preoperative value. This difference was statistically significant (P = 0.001). The rise in CSF-AK was most probably the result of an enhanced efflux of AK into CSF subsequent to a presumed hypoxic injury to brain cells.

Adenylate Kinase↗
PubMedDate not supplied

Low frequency of adenylate kinase release into cerebrospinal fluid during balanced, normotensive anaesthesia and a non-orthognathic surgical procedure.

Activity of strictly intracellular enzymes in the cerebrospinal fluid (CSF) may indicate leakage from dysfunctional brain cells. Increased activity of adenylate kinase (AK) in the CSF is indicative of brain cell injury arising from several sources, among them orthognathic surgery. The mechanism in the latter case is obscure, but the use of an oscillating saw which generates vibrations, and the site of surgery close to the brain may be contributing factors. Anaesthesia may also play a role. In the present study, CSF-AK activity was measured after hysterectomy and was compared with activity after orthognathic surgery in two other studies. Four of 19 patients (21%) in the present study expressed pathological activity, compared with 34 of 47 (72%) orthognathic patients in the two other studies. No firm conclusion may be drawn from historical comparisons, and the difference in activity seen between the two types of surgery might not necessarily be the result of surgical factors. Until this is investigated further, however, we conclude that there may be a difference in postoperative CSF-AK activity between orthognathic and lower abdominal surgery.

Adenylate Kinase↗