Biomedical subjects

Arvi Yli-Hankala

Publications and source records attributed to Arvi Yli-Hankala.

7 recordsLinked to original sources

PubMed2006

Entropy is more resistant to artifacts than bispectral index in brain-dead organ donors.

OBJECTIVE: To evaluate the usefulness of entropy and the bispectral index (BIS) in brain-dead subjects. DESIGN AND SETTING: A prospective, open, nonselective, observational study in the university hospital. PATIENTS AND PARTICIPANTS: 16 brain-dead organ donors. INTERVENTIONS: Time-domain electroencephalography (EEG), spectral entropy of the EEG, and BIS were recorded during solid organ harvest. MEASUREMENTS AND RESULTS: State entropy differed significantly from 0 (isoelectric EEG) 28%, response entropy 29%, and BIS 68% of the total recorded time. The median values during the operation were state entropy 0.0, response entropy 0.0, and BIS 3.0. In four of 16 organ donors studied the EEG was not isoelectric, and nonreactive rhythmic activity was noted in time-domain EEG. After excluding the results from subjects with persistent residual EEG activity state entropy, response entropy, and BIS values differed from zero 17%, 18%, and 62% of the recorded time, respectively. Median values were 0.0, 0.0, and 2.0 for state entropy, response entropy, and BIS, respectively. The highest index values in entropy and BIS monitoring were recorded without neuromuscular blockade. The main sources of artifacts were electrocauterization, 50-Hz artifact, handling of the donor, ballistocardiography, electromyography, and electrocardiography. CONCLUSION: Both entropy and BIS showed nonzero values due to artifacts after brain death diagnosis. BIS was more liable to artifacts than entropy. Neither of these indices are diagnostic tools, and care should be taken when interpreting EEG and EEG-derived indices in the evaluation of brain death.

Artifacts↗

PubMed2005

Spectral entropy monitoring is associated with reduced propofol use and faster emergence in propofol-nitrous oxide-alfentanil anesthesia.

BACKGROUND: This multicenter study evaluated the effect of a new depth of anesthesia-monitoring device based on time-frequency-balanced spectral entropy of electroencephalogram monitoring (GE Healthcare Finland, Helsinki, Finland) on consumption of anesthetic drugs and recovery times after anesthesia. METHODS: The study was a prospective, randomized, single-blind study performed in six hospitals in Finland, Sweden, and Norway. After institutional review board approval and written informed consent from each patient, the patients were randomly allocated to anesthesia with entropy values either shown (entropy group) or not shown (control group). Anesthesia was maintained with propofol, nitrous oxide, and alfentanil. In the entropy group, propofol was given to keep the state entropy value between 45 and 65, and alfentanil was given to keep the state entropy-response entropy difference below 10 units and heart rate and blood pressure within +/-20% of the baseline values. The control group patients were anesthetized to keep heart rate and blood pressure within +/-20% of the baseline values. Statistical methods included Mann-Whitney U test and unpaired t tests. RESULTS: A total of 368 patients were studied. In the entropy group, entropy values were higher during the whole operation and especially during the last 15 min (P < 0.001). Consequently, propofol consumption was smaller in the entropy group during the whole anesthesia period (P < 0.001) and especially during the last 15 min (P < 0.001). This shortened the time delay in the early recovery parameters in the entropy group. CONCLUSION: Entropy monitoring assisted titration of propofol, especially during the last part of the procedures, as indicated by higher entropy values, decreased consumption of propofol, and shorter recovery times in the entropy group.

Adult↗

PubMed2005

Maternal hemodynamics during cesarean delivery assessed by whole-body impedance cardiography.

BACKGROUND: This descriptive study was designed to evaluate maternal hemodynamics and cardiovascular responses to delivery during cesarean section (CS) under spinal anesthesia. We also assessed the feasibility of a noninvasive and continuous method of measuring cardiac output, namely whole-body impedance cardiography (ICG(WB)), during elective CS. Because of the techniques used in previous studies, only fractionated data on maternal hemodynamics during CS are available to date. METHODS: We studied 10 healthy women with normal pregnancies and two pregnant women with heart disease undergoing elective CS. Mean arterial pressure (MAP), heart rate (HR), stroke index (SI), cardiac index (CI) and systemic vascular resistance index (SVRI) were recorded continuously during CS, during the period of dissipation of anesthesia and on the second to fifth postpartum day. Analysis of variance for repeated measurements (anova) and the paired sample t-test were used in statistical analysis. RESULTS: The hemodynamic parameters could be registered continuously during the whole procedure. At the point of delivery, a 47% increase in CI and a 39% decrease in SVRI were recorded, while MAP remained stable. These changes occurred within 2 min of delivery of the newborn and persisted on average for 10 min. CONCLUSION: Sudden and significant hemodynamic changes take place at the moment of delivery. Intact physiological cardiovascular compensation mechanisms are needed to adapt to these challenges. Whole-body impedance cardiography may offer a useful noninvasive tool to monitor hemodynamics during cesarean section.

Adult↗

PubMed2004

Gabapentin for the prevention of postoperative pain after vaginal hysterectomy.

Gabapentin alleviates and/or prevents acute nociceptive and inflammatory pain both in animals and volunteers, especially when given before trauma. Gabapentin might also reduce postoperative pain. To test the hypothesis that gabapentin reduces the postoperative need for additional pain treatment (postoperative opioid sparing effect of gabapentin in humans), we gave 1200 mg of gabapentin or 15 mg of oxazepam (active placebo) 2.5 h prior to induction of anaesthesia to patients undergoing elective vaginal hysterectomy in an active placebo-controlled, double blind, randomised study. Gabapentin reduced the need for additional postoperative pain treatment (PCA boluses of 50 microg of fentanyl) by 40% during the first 20 postoperative hours. During the first 2 postoperative hours pain scores at rest and worst pain score (VAS 0-100 mm) were significantly higher in the active placebo group compared to the gabapentin-treated patients. Additionally, pretreatment with gabapentin reduced the degree of postoperative nausea and incidence of vomiting/retching possibly either due to the diminished need for postoperative pain treatment with opioids or because of an anti-emetic effect of gabapentin itself. No preoperative differences between the two groups were encountered with respect to the side effects of the premedication. However, 15 mg oxazepam was more effective in relieving preoperative anxiety than 1200 mg gabapentin.

Acetates↗

PubMed2004

Induction of therapeutic hypothermia after cardiac arrest in prehospital patients using ice-cold Ringer's solution: a pilot study.

The cooling and haemodynamic effects of prehospital infusion of ice-cold Ringer's solution were studied in 13 adult patients after successful resuscitation from non-traumatic cardiac arrest. After haemodynamics stabilisation, 30 ml/kg of Ringer's solution was infused at a rate of 100ml/min into the antecubital vein. Arterial blood pressure and blood gases, pulse rate, end-tidal CO(2) and oesophageal temperature were monitored closely. The mean core temperature decreased from 35.8 +/- 0.9 degrees C at the start of infusion to 34.0 +/- 1.2 degrees C on arrival at hospital (P < 0.0001). No serious adverse haemodynamic effects occurred. It is concluded that the induction of therapeutic hypothermia using this technique in the prehospital setting is feasible.

Adult↗

PubMed2004

Monitoring the electroencephalogram during bypass procedures.

Electroencephalographic monitoring has been performed since the early days of cardiopulmonary bypass. Despite this long experience, the technology has never been widely used for cardiac operations. This review examines the reasons for the limited use and describes technological advances that may alter this pattern.

Anesthesia, General↗

PubMed2002

Methods for assessing adequacy of anesthesia.

Assessing adequacy of anesthesia requires evaluation of its components: hypnosis, analgesia, and neuromuscular transmission. In order to do this, many methods have been developed that process signals representing different modalities. Assessment of hypnosis requires cortical measures of the central nervous system (CNS); methods that assess analgesia concentrate on subcortical and spinal levels of the CNS; and neuromuscular transmission is a peripheral phenomenon. This article presents an overview of the current state of methods available for measuring each of these components. We conclude that, whereas important gains have been made in the area of assessment of hypnosis, mainly owing to the advancement of methods using EEG and auditory evoked potentials, and whereas neuromuscular transmission can be objectively monitored using motor nerve stimulation, assessment of analgesia still contains many challenges.

Anesthesia↗