Unilateral, site-specific microinjection of fentanyl (2.5 micrograms/50 nl) into the locus coeruleus (LC) in Sprague-Dawley rats anesthetized with ketamine evoked a significant increase in the electromyographic activity recorded from both caudal lateral extensor and gastrocnemius muscles. This correlate of opiate-induced muscular rigidity was appreciably antagonized by a pretreatment with the specific alpha 1-adrenoceptor blocker, prazosin (250 micrograms/kg, i.v.). On the other hand, an equimolar dose (0.65 mumol/kg) of the specific alpha 2-adrenoceptor blocker, yohimbine (0.23 mg/kg, i.v.) failed to prevent the occurrence of fentanyl-induced EMG activation. We suggest that the coerulospinal noradrenergic pathway may be directly involved in the elicitation of muscular rigidity by fentanyl, possibly via alpha 1-adrenoceptors in the spinal cord.

Adrenergic Fibers↗

PubMed1990

The use of ketanserin for postoperative hypertension after abdominal surgery.

Eighteen adult patients who developed hypertension (systolic blood pressure greater than 160 mmHg, diastolic blood pressure greater than 90 mmHg or both) at the early recovery period after major abdominal surgery were included in the study. Following intravenous injection of 10 mg ketanserin, eleven out of eighteen patients (61%) had their systolic or diastolic blood pressure fell below the target mark (160 mmHg and 90 mmHg), and the decrease was statistically significant (p less than 0.01 up to 120 min). There was no statistically significant change in heart rate. Four patients (22%) responded to 20 mg of ketanserin. Three patients (17%) did not have significant decrease of the blood pressure after 20 mg of ketanserin and they received other antihypertensives instead. No severe hypotensive episode was noted. We concluded that ketanserin is a moderate, rapid-onset and safe antihypertensive agent in treating postoperative hypertension following major abdominal surgery.

Abdomen↗

PubMed1990

Clinical application of infrared thermography in diagnosis and therapeutic assessment of vascular ischemic pain.

Temperature is a very important and useful manifestation of various disease entities. The importance of body temperature as an indicator of disease has been known for centuries but in recent years attention has also been paid to how to conveniently and effectively make use of skin temperature as a diagnostic tool. Skin temperature can be measured with thermocouples, electronic thermistor-thermometers, electronic integrators, liquid crystal thermography, and infrared thermography. The temperature of extremities is largely dependent on the blood flow through peripheral vessels, and in the study of vascular diseases thermography has been, therefore, found to be useful. Blood flow can be assessed by many methods including washout techniques or laser Doppler flowmetry. Of these, infrared thermography has the advantages of being noninvasive, remote from the patient when in use, and capable of producing multiple recordings at short time intervals. Here we present a case of vascular ischemic pain which was diagnosed and therapeutically assessed by thermography.

Aged↗

PubMed1990

Activation of epileptogenic activities by etomidate in electrocorticoencephalography (ECoG) during operation for epilepsy.

Epileptic surgery is a radical and ablative treatment for medically refractory epilepsy. Electrocorticoencephalography (ECoG) obtained by subdural strip electrodes should always be used during operation for precise localization of epileptic focus and mapping the extent of its involvement. But difficulties and ambiguities exist when the patient's ECoG is suppressed, either owing to the anticonvulsant used, being at the stage of posterictal period, or the effects of anesthetics during operation. Then, intentional activation of epileptogenic activity should be performed to locate the pathological focus in order to accomplish a successful surgical treatment. Etomidate has been considered as an abnormal electroencephalogram (EEG) activator and its use is not recommended in patients with epilepsy. But lesser dose of etomidate as an activator for ECoG has not been investigated. The study reported here established that etomidate as an hypnotic has not only anesthetic properties but, paradoxically, also activates epileptogenic activity. With the latter pharmacologic characteristic, etomidate can be used to deliberately activate the spikes of the potentially epileptogenic tissue, the delineation and localization of which may help the surgeon determine to what extent the pathological cortex be resected in surgical treatment of a refractory epilepsy. The current recommended dosage of etomidate at veterans General Hospital-Taipei for ECoG in epileptic surgery is 0.1-0.15 mg/kg/iv.

Adolescent↗

PubMed1990

Early detection of cerebral dysfunction by quantitative EEG during cardiopulmonary-bypass period for open-heart surgery.

Neuropsychiatric complications are well known risks of open heart surgery. In this regard cerebral damage is caused either by microembolism or insult from low perfusion pressure as a consequence of extracorporeal circulation. It seems probable that monitoring of the quantitative electroencephalography (QEEG) during the surgical procedure can help minimize the incidence of neurological sequelae through early detection. Moreover, it seems important to establish whether the pre-operative EEG has a predictive value for the possible neurological outcome and whether the post-operative EEG has conclusive value for the neurological outcome and, above all to ascertain whether the peri-operative QEEG contains information valuable on the diagnosis of final neurological outcome. To elucidate the feasibility of QEEG as a means to monitor the cerebral function a study was thus undertaken. Twenty-five ASA II-IV patients with age ranging from 25-79 y/o undergoing cardiac surgery under extracorporeal circulation were enrolled for study. The types of surgery varied from coronary artery by-pass graft (CABG), valvular replacement, and excision and grafting for aortic dissecting aneurysm. 16-channel EEGs were recorded with a Cadwell Spectrum 32 in accordance with the international 10-20 system. 48 epochs (1 epoch = 2.5 seconds) of EEG recordings of pre-bypass and post-bypass periods were measured and quantitatively analyzed. Pre- & post-operatively, psychoneurological assessments were performed and correlated with the QEEG. The parameters employed in the study were absolute power, relative power, power asymmetry, and coherence. All the results of two-session comparisons were transformed into z score values. Our preliminary study revealed that there exists a specific multivariate profile of QEEG for specific disease entity. And all the patients with z score less than or equal to 3.0 turned out to be free from any significant sequelate.

Adult↗

PubMed1990

Demarcation and localization of primary sensor and motor areas in human cortex by cortical somatosensory. Evoked potential (Co-SEP) during operation in surgery for epilepsy and intracranial tumor.

In neurosurgical operation, when the focus is close to the central fissure, precise delineation of the precentral motor and postcentral somatosensory areas is cardinal in defining the extent of the surgical resection. Eight ASA II-III patients scheduled for neurosurgery for intractable complex partial seizure (n = 5) and intracranial tumor (n = 3) were enrolled in the study. Subdural grids of electrodes were used for recording cortical evoked somatosensory potentials elicited by stimulating the median nerves to locate the primary somatosensory cortex and to delineate the central fissure through demonstration of phase-reversal pattern across the rolandic fissure. In all cases under general anesthesia, we were able to determine precisely the location of the central fissure. At the same time, we detected the evoked potential from SII (second sensory area) in one patient with intracerebral tumor. In conclusion, Co-SEP under general anesthesia is feasible and recommended to be performed as a routine intraoperatively for intractable epilepsy and tumor originating close to the primary motor or sensory strip in order to avoid iatrogenic damage to the vital cerebral cortex.

Brain Neoplasms↗

PubMed1989

Involvement of locus coeruleus and noradrenergic neurotransmission in fentanyl-induced muscular rigidity in the rat.

Whereas muscular rigidity is a well-known side effect that is associated with high-dose fentanyl anesthesia, a paucity of information exists with regard to its underlying mechanism(s). We investigated in this study the possible engagement of locus coeruleus of the pons in this phenomenon, using male Sprague-Dawley rats anesthetized with ketamine. Under proper control of respiration, body temperature and end-tidal CO2, intravenous administration of fentanyl (50 or 100 micrograms/kg) consistently promoted an increase in electromyographic activity recorded from the gastrocnemius and abdominal rectus muscles. Such an induced muscular rigidity by the narcotic agent was significantly antagonized or even reduced by prior electrolytic lesions of the locus coeruleus or pretreatment with the alpha-adrenoceptor blocker, prazosin. Microinjection of fentanyl (2.5 micrograms/50 nl) directly into this pontine nucleus, on the other hand, elicited discernible electromyographic excitation. It is speculated that the induction of muscular rigidity by fentanyl may involve the coerulospinal noradrenergic fibers to the spinal motoneurons.

Adrenergic Fibers↗

PubMed1989

Differential effects of prazosin and yohimbine on fentanyl-induced muscular rigidity in rats.

Whereas muscular rigidity is a well-known phenomenon that is related to anesthesia induced by large doses of narcotic drugs, the precise underlying mechanism(s) remain to be fully elucidated. This study investigated the possible role of noradrenergic neurotransmission and the participation of alpha-adrenoceptors in this phenomenon. Male Sprague-Dawley rats, under ketamine-induced anesthesia (120 mg/kg, i.p.) and with proper control of respiration, body temperature and end-tidal CO2 were used. Intravenous administration of fentanyl (100 micrograms/kg) consistently caused a significant increase in the electromyographic (EMG) activity, recorded from both gastrocnemius and abdominal rectus muscles. This implied muscular rigidity was markedly antagonized by pretreatment with the specific alpha 1-adrenoceptor blocker, prazosin (50 or 250 micrograms/kg, i.v.). This antagonism occurred in spite of a high level of fentanyl in the plasma, as determined by radioimmunoassay. The specific alpha 2-adrenoceptor blocker, yohimbine (1.15 or 2.3 mg/kg, i.v.), on the other hand, not only failed to prevent fentanyl-induced activation of the EMG, but actually potentiated the response. It is concluded that noradrenergic neurotransmission, possibly originating from the locus coeruleus, may participate in the elicitation of muscular rigidity by fentanyl. Furthermore, this process may involve an excitatory action through alpha 1-, and an inhibitory action through alpha 2-adrenoceptors, in the spinal cord.

Animals↗

PubMed1989

Fentanyl-induced muscle rigidity in unanesthetized and ketamine- or thiopental-anesthetized rats.

This study was undertaken to search for an alternative experimental model in the evaluation of fentanyl-induced muscle rigidity. Unanesthetized, spontaneously ventilating Sprague-Dawley rats, and rats anesthetized with either ketamine or thiopental whose ventilation was mechanically controlled, were studied. Intravenous administration of fentanyl (25, 50, or 100 micrograms/kg) caused an increase in electromyographic (EMG) activity in both unanesthetized and ketamine-anesthetized, but not in thiopental-anesthetized, animals. Muscle rigidity was more prominently manifested in the gastrocnemius muscle, when compared with the rectus abdominis muscle. Hypoxemia was exhibited during the course of rigidity by both spontaneously ventilating and ketamine-anesthetized rats, but not by thiopental-anesthetized animals. In addition, unanesthetized, spontaneously ventilating rats developed hypercarbia and respiratory acidosis. The authors suggest that, in addition to using unanesthetized animals, EMG activity in the gastrocnemius muscle of rats anesthetized with ketamine in whom ventilation is controlled may provide an alternative approach in the evaluation of fentanyl-induced muscle rigidity.

Anesthesia↗

PubMed1988