Transcutaneous electrical nerve stimulation (TENS) in the treatment of postoperative pain and prevention of paralytic ileus

This study was performed on 30 patients who had undergone various gynaecological operations. Transcutaneous electrical nerve stimulation (TENS) was used on 17 patients and placebo TENS on the remaining 13. Pain severity, the need for analgesic drugs and the presence of paralytic ileus were evaluated in all patients during the first three postoperative days. There was no significant difference in pain severity between the two groups in the immediate postoperative period ( p > 0.5). However, evaluations performed at the end of the first, second and third postoperative days revealed a very significant difference in pain severity ( p < 0.01) and analgesic drug use in the two groups. A comparison of postoperative complications showed paralytic ileus in seven patients in the placebo group (54%); only two patients in the TENS group (12%) showed the same symptoms. Significant analgesia, an important reduction in analgesic drug use and a decrease in the incidence of paralytic ileus were observed as a result of the application of TENS in the postoperative period.

Subclinical Dysfunction of Cochlea and Cochlear Efferents in Migraine: An Otoacoustic Emission Study

Otoacoustic emission (OAE) testing enables us to identify the cochlear component of a hearing disorder and to monitor objectively minute changes in cochlear status undetectable by other audiological methods. Contralateral sound-induced suppression is mediated by medial superior olivary complex efferents which induce hyperpolarization counteracting the amplifying effects of outer hair cell (OHC) activity. The aim of this study was to assess functions of cochlea and its efferents in migraine using OAE testing and contralateral suppression of transiently evoked OAEs (TEOAE). Fifty-three migraineurs (106 ears) and 41 healthy subjects (82 ears) were included and pure tone audiometry (PTA), speech discrimination scores (SDS), distortion product OAE (DPOAE), TEOAE and contralateral suppression of TEOAEs were tested. PTA and SDS of migraineurs and controls were not different ( P > 0.05). DPOAEs were tested between 1 and 6 kHz and a significant difference was detected only at 5 kHz frequency, where DPOAE amplitudes in migraine with aura (MA) were lower than in controls ( P < 0.03). The mean amplitudes of TEOAEs were statistically insignificant between controls and migraine groups. Contralateral sound stimulus induced significant decrease in amplitudes of TEOAE ( P = 0.005) in controls. In patients with migraine without aura and MA, mean amplitudes of TEOAEs were not suppressed by contralateral sound stimulus ( P > 0.05). As PTA, SDS and DPOAE tests demonstrate normal functioning of inner ear between 1 and 4 kHz, absence of suppression of the TEOAEs by contralateral sound stimulation indicates the presence of dysfunction either in the medial olivocochlear complex in the brainstem or at the synaptic transmission between olivocochlear efferents and OHCs in the cochlea. Disruption in the contralateral suppression may be one of the mechanisms predisposing to the phonophobia symptom associated with migraine headache.

Alkalinisation of local anaesthetics prescribed for pain relief after surgical decompression of carpal tunnel syndrome

PURPOSE

To compare the duration of analgesia achieved following administration of buffered prilocaine versus plain prilocaine to patients undergoing surgical decompression of the median nerve.

METHODS

40 (32 female and 8 male; mean age, 50.5 years) patients who underwent surgical decompression of carpal tunnel syndrome were recruited. Patients were randomly allocated to 2 groups: the alkalinised group was given 10 ml of prilocaine hydrochloride 2% buffered with 1 ml of sodium bicarbonate 8.4%, whereas the non-alkalinised group received 10 ml of plain prilocaine hydrochloride 2% solution. Patients were asked to rate their comfort level at the operation site in the first 6 hours following surgery and after discharge from hospital using a visual analogue scale (VAS). The duration of analgesic effect was evaluated every 3 hours. Additional oral analgesia in the form of paracetamol 500 mg tablets was available to patients if required for break-through pain.

RESULTS

Significantly lower VAS scores were reported by the alkalinised group during the first postoperative 12 hours. The change of VAS scores over time was significantly higher in the non-alkalinised group. The mean analgesic requirement for paracetamol tablets in the alkalinised and non-alkalinised groups was 4 and 34, respectively.

CONCLUSION

Buffered prilocaine provided a longer postoperative pain-free period for patients undergoing surgical decompression of the median nerve. It is easy, safe, and cost-effective.

Effect of positional change and inhalant anesthesia on parameters of acoustic reflectometry

OBJECTIVE

Purpose of this study was to find out the effect of positional change and inhalant anesthesia on acoustic reflectometry (AR) parameters (reflectivity and curve angle).

METHOD

AR parameters were measured on 58 ears with otitis media in sitting position before anesthesia and in supine position under inhalant anesthesia, subsequently.

RESULTS

Under anesthesia, ears with effusion disclosed more changes in reflectivity (Chi-squared analysis, chi2-test; P<0.05) and curve angle (P>0.1) than those without effusion. Further, inhalant anesthesia caused more changes in the false negative ears (63.63%) than in those with effusion having positive test before anesthesia (12.90%) (P<0.001).

CONCLUSIONS

From the data of this study, it could be said that reflectivity shows changes according to the amount of effusion which is in contact with the tympanic membrane under anesthesia, and that curve angle becomes more sensitive to detect effusion when anesthetic gas diffuses into the middle ear with effusion, probably due to the pushing of effusion towards the tympanic membrane.

Cerebral hypoperfusion after cardiac surgery and anesthetic strategies: a comparative study with high dose fentanyl and barbiturate anesthesia

BACKGROUND

Postoperative delirium is a common sequel of cardiopulmonary bypass that is hard to diagnose correctly, difficult to predict and almost impossible to prevent and to treat. The aim of this study is to evaluate the frequency of postoperative cognitive disorders and cerebral hypoperfusion in patients receiving either high dose fentanyl or thiopentone anesthesia in cardiac surgery.

METHODS

50 unpremedicated patients, Class IIb-NYHA (25 patients in each group suffering from single critical LAD disease) undergoing elective coronary artery bypass grafting surgery were randomly allocated into two groups either to receive fentanyl 50 microg/kg with diazepam 0.1 mg/kg (Group 1) or thiopentone 7 mg/kg (Group 2) for the induction of anesthesia. Anesthesia was maintained with fentanyl 2 microg/kg/hr and diazepam 0.05 mg/kg/hr infusion in Group 1 throughout the procedure. In Group 2, it was maintained with enflurane 0.7-1.5% before and after cardiopulmonary bypass (CPB) and with thiopentone 3 mg/kg/hr infusion during CPB. Neuropsychiatric evaluation (STAI-T, min mental state examination-MMSE and Zung tests), EEG and SPECT rCBF (Single Photon Emission Computed Tomography Regional Cerebral Blood Flow) studies were performed preoperatively, early and late postoperatively. The patients that were diagnosed to have postoperative cerebral hypoperfusion also underwent computed tomography scanning postoperatively.

RESULTS

Eleven patients (9 from fentanyl and 2 from thiopentone group) were diagnosed to have cerebral hypoperfusion with respect to SPECT rCBF studies. Seven of these patients (5 from fentanyl and 2 from thiopentone) were diagnosed to be in a state of delirium clinically with MMSE tests.

CONCLUSION

High dose fentanyl anesthesia causes significant predisposition to postoperative cerebral hypoperfusion when compared with barbiturate anesthesia in cardiac surgery. Hypoperfusion as demonstrated by SPECT rCBF studies may play an important role in the pathophysiology of mental disorders, i.e., postoperative delirium.

Psychiatric complications of cardiac surgery postoperative delirium syndrome

Psychiatric disturbances due to cardiopulmonary bypass, especially postoperative delirium syndrome, are among the immediate complications of open-heart surgery. In a series of 32 male and 18 female patients the prevalence of such disorders was investigated and search was made for possible risk factors for their occurrence. Psychiatric, neurologic and electroencephalographic evaluation was made pre- and postoperatively, in addition to haemodynamic, echocardiographic, angiographic and regional cerebral blood flow studies. Nine of the 50 patients had significantly reduced perfusion of certain cerebral lobes in single photon emission computed tomography, and in six of them the psychiatric tests indicated postoperative delirium; three of these six also had moderate electroencephalographic changes. The cerebral hypoperfusion persisted on day 15 in four patients, while psychiatric tests were negative. The study showed possible risk factors to be patient age, long aortic cross-clamp time, high-dose inotropic support and excessive transfusion of blood or blood products.

Pulmonary microvascular injury following general anaesthesia with volatile anaesthetics--halothane and isoflurane: a comparative clinical and experimental study

Pulmonary microvascular injury has become a recently studied phenomenon that may be responsible for most of the complications associated with the lungs. Thirty patients undergoing partial hemilaminectomy or discectomy due to hernia of nucleus pulposus underwent Tc-99m HMPAO lung clearance as well as Tc-99m pertechnetate lung scintigraphy pre-operatively, and following general anaesthesia with halothane and isoflurane (third, fourth and tenth post-operative days). The results were compared with conventional techniques and haemodynamic parameters during the peri-operative period. In order to demonstrate acute phase changes under general anaesthesia and to perform pathological examinations, 21 New Zealand rabbits underwent radionuclide studies with Tc-99m HMPAO or Tc-99m pertechnetate. Lung biopsies were also performed. Despite no significant differences in any of the conventional diagnostic techniques, Tc-99m pertechnetate lung scintigraphy was performed for both the halothane and isoflurane groups, and Tc-99m HMPAO lung clearance was performed for the isoflurane group pre- or post-operatively. Tc-99m HMPAO lung clearance was impaired significantly in the halothane group on the third post-operative day (half time: 6.4 +/- 1.6 pre-operative and 13.76 +/- 3.3 s, P < 0.001) decreasing to pre-operative levels on the tenth post-operative day. Acute phase exposure to halothane was characterized with extremely abnormal Tc-99m HMPAO lung clearance in rabbits with respect to isoflurane, diminishing to control levels on the third day (half time: 8.7 +/- 86 control and 28.65 +/- 4.6, P < 0.001). Pathological examinations also demonstrated endothelial damage on acute exposure in the halothane group. General anaesthesia with halothane may give rise to alveolar microvascular injury, which generally seems to be underdiagnosed and may lead to serious post-operative complications.

The effect of propofol on systemic vascular resistance during cardiopulmonary bypass: a comparative study with thiopentone

30 patients undergoing elective coronary artery bypass grafting surgery were allocated randomly to receive either propofol--2.5mg/kg--(N = 10, Group I) or thiopentone--4mg/kg--(N = 10, Group II) during cardiopulmonary bypass with constant pump flow and temperature. Two groups and another control group-receiving no medication-(N = 10, Group III) were compared with respect to the changes in hemodynamic parameters, especially systemic vascular resistance (SVR). After propofol, SVR decreased from 2489 +/- 302 to 1594 +/- 286 dyn sec cm-5 and remained significantly less than the control values until 16.6 +/- 4 min. after the administration of propofol. Following thiopentone administration, SVR decreased from 2653 +/- 298 to 2162 +/- 279 dyn sec cm-5 and remained so for the following 9.4 +/- 3 min. There were more significant decreases in especially cardiac index, perfusion pressure and SVR in the propofol group compared with thiopentone or control groups. Cardiopulmonary bypass has been shown to be a useful model for studying the isolated effects of anesthetic drugs on hemodynamic parameters. In our study, we tried to discuss the mechanism of the hypotensive effects of anesthetic agents, especially propofol and give an idea about the possible precautions that should be taken.

Perineural pethidine: effects of different doses on nerve conduction

Forty healthy young volunteers were divided randomly into four equal groups. 2 ml of solutions of pethidine (meperidine) in concentrations of 0.5%, 1% and 1.5% were given to three groups of 10 subjects: a fourth group received saline. Sensory evoked responses obtained via surface electrodes from both sural nerves simultaneously in the pethidine groups and unilaterally in the control group, were evaluated for latency, conduction velocity and amplitude. Sensory changes at the innervation zone were monitored by means of a pinprick. All recordings were obtained prior to injection and at 5 min intervals for 30 min. Concentrations of 1% and 1.5% pethidine were associated with significantly lower amplitudes and with hypoalgesia. Other parameters did not change.

Effects of perineural opioids on nerve conduction of N. suralis in man

In this study the effects of agonist acting drugs (morphine sulphate, fentanyl citrate and meperidine hydrochloride) on nerve conduction were studied in 43 healthy young volunteers divided into four groups randomly. According to analgesic equivalent doses, the first group received 2 mg morphine sulphate, the second group 0.02 mg fentanyl citrate, the third group 20 mg meperidine hydrochloride, and as control the fourth group received 2 ml of saline. The latencies, amplitudes of the responses and nerve conduction velocities were obtained immediately before and every 5 min after injections up to 30 min. No significant change was observed within or among the morphine sulphate, fentanyl citrate and saline groups whereas in the meperidine hydrochloride group the amplitudes diminished significantly and this finding was still apparent at 30 min. Four of the cases displayed complete blocks. Nerve conduction velocity did not change in the other 6 cases. The significant decrement of the amplitude of the compound nerve action potential in the meperidine hydrochloride group is probably due to local anesthetic-like action of this drug. Morphine sulphate, fentanyl citrate or saline did not show this effect.

The histopathological comparison of the results of the intra-arterial injections of propofol and thiopentone in rabbits

The results of injections of propofol and thiopentone intra-arterially are compared in rabbits according to histopathological criteries. Thirteen New Zealand type rabbits are used. Two ml of 2.5% Thiopentone and 2 ml of 1% Propofol are administered to the rabbits under anesthesia. Three days after, their ears are amputated and sent to this pathological blind examination. In both groups, we saw neither a morphological change along the vessel walls nor significant bleeding. But between the groups there was a significant difference about oedema. Consequently, 2.5% thiopentone which is routinely used after intra-arterial administration, may be responsible of the gangrenous change but it is discussable and it makes significant oedema in animal models although propofol does not have this effect.