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G Iohom

Publications and source records attributed to G Iohom.

15 recordsLinked to original sources
PubMed2006

An objective assessment of nerve stimulators used for peripheral nerve blockade*.

Nerve stimulation is considered by many to be the current 'gold standard' for locating peripheral nerves. Thirteen nerve stimulators were subjected to a battery of tests performed by two independent observers under standardised conditions using a digital oscilloscope, a calibrated resistance and a novel scoring system. Individual scores were assigned for the signal waveform, current intensity, impulse duration, maximum load output and functionality of each nerve stimulator; the maximum score achievable was 20. A score of > or = 15/20 was achieved by six nerve stimulators: Stimuplex HNS 12 (B Braun); MultiStim Vario (Pajunk); Plexival (Medival, Vygon); MultiStim Sensor (Pajunk); Plexygon (Aryon, Vygon); Stimuplex HNS 11 (B Braun). Seven nerve stimulators scored < 15/20. Anaesthetists should be aware of the limitations of the nerve stimulator being used. Standardisation of features is desirable when manufacturing nerve stimulators.

Electric Stimulation↗
PubMed2005

Effects of levobupivacaine and ropivacaine on rat sciatic nerve blood flow.

BACKGROUND: Ischaemia is one of the causative mechanisms of peripheral nerve injury, a documented complication of regional anaesthesia. Local anaesthetics per se and/or vasopressor adjuvants may account for changes in peripheral nerve blood flow. The aim of this study was to test the effects of levobupivacaine and ropivacaine in a rat sciatic nerve model with respect to local blood flow and histopathological changes. METHODS: Forty-eight female Sprague-Dawley rats were anaesthetized for left sciatic nerve exposure. After baseline nerve blood flow measurement with a laser Doppler flowmeter, 0.2 ml of one of the following solutions was applied topically to the nerve in a random fashion: saline 0.9%; lidocaine 10 mg ml(-1); levobupivacaine 2.5 mg ml(-1); levobupivacaine 5 mg ml(-1); levobupivacaine 7.5 mg ml(-1); ropivacaine 2 mg ml(-1); ropivacaine 7.5 mg ml(-1); and ropivacaine 7.5 mg ml(-1) plus epinephrine 5 microg ml(-1); all in saline 0.9%. Nerve blood flow was evaluated at 5-min intervals up to 30 min after local application of anaesthetic solution. Three animals per group were killed for histological evaluation 48 h later. Multiple one-way analyses of variance followed by Scheffé's post hoc test was used for statistical analysis. P<0.05 was considered significant. RESULTS: Local anaesthetics at all concentrations tested caused significant reduction in nerve blood flow. The combination of ropivacaine 7.5 mg ml(-1) plus epinephrine did not reduce nerve blood flow to a greater extent than ropivacaine 7.5 mg ml(-1) alone. Low concentrations of levobupivacaine (2.5 and 5 mg ml(-1)) reduced nerve blood flow to the same extent as lidocaine 10 mg ml(-1). No significant histological changes were observed at 48 h. CONCLUSION: Despite acute reductions in peripheral nerve blood flow, significant histopathological changes were not observed in this rat sciatic nerve model after topical application of levobupivacaine and ropivacaine at concentrations relevant to clinical practice.

Amides↗
PubMed2005

Long-term evaluation of motor function following intraneural injection of ropivacaine using walking track analysis in rats.

BACKGROUND: There is a paucity of data regarding neurologic function following nerve injury. Our objective was the long-term evaluation of motor function following intraneural injection of ropivacaine in rats using the sciatic function index (SFI), derived from walking track analysis. METHODS: Rats were randomly assigned to one of four groups of 13 animals each. A needle was inserted under magnification into the left sciatic nerve and 0.2 ml of normal saline, formalin 15%, ropivacaine 0.2 or 0.75% were injected intraneurally. The right side was sham operated. Walking track analysis was performed the day before and on days 1, 4, 7, 11, 15, 18, 21, and 67 following intraneural injection. At the end of the experiment (day 67) a semi-quantitative evaluation of neuropathologic changes was performed by three independent observers. RESULTS: Animals treated with saline and ropivacaine (0.2 and 0.75%) had no detectable impairment of motor function at any time point. In contrast, rats treated with formalin had a complete loss of motor function immediately after the intraneural injection, which persisted until day 21 and returned to normal by day 67. Important histopathologic changes (score=2) with excellent inter-observer agreement were seen only in the group treated with formalin. This applied to both axonal degeneration and Schwann cell density evaluations. CONCLUSIONS: These findings suggest that intraneural injections of ropivacaine at concentrations routinely used in clinical practice appear to have no deleterious effect on sciatic nerve motor function in this experimental rat model.

Amides↗
PubMed2004

Postoperative changes in the full-field electroretinogram following sevoflurane anaesthesia.

BACKGROUND AND OBJECTIVE: We tested the hypothesis that disturbances of the visual pathway persist following general anaesthesia, even after normal clinical discharge criteria have been met. METHODS: We performed full-field flash electroretinography in the right eye of 10 unpremedicated ASA I patients who underwent N2O/sevoflurane anaesthesia. Electroretinograms were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which postanaesthesia discharge score first exceeded 9 was also noted. Data were analysed using paired, one-tailed Student's t-test. RESULTS: Latency of the b-wave on the photopic electroretinogram was greater at each postoperative time point (30.5 +/- 0.9 and 30 +/- 1.3 ms), compared to preoperative values (29.2 +/- 0.8 ms, P < 0.001 and P = 0.04, respectively). The A-B amplitude of the b-wave was less postoperatively (220.3 +/- 52.7 and 210.3 +/- 42.7 pV) compared to values before operation (248.1 +/- 57.6 microV, P = 0.03 and P = 0.01, respectively). Oscillatory potential latencies were greater at each postoperative time point (21.4 +/- 0.5 and 20.8 +/- 0.6 ms) compared to before operation (20.4 +/- 0.4 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential amplitudes were less at the first postoperative time point (17.5 +/- 6.1 microV), compared to preoperative values (22 +/- 6.4 microV, P = 0.04). CONCLUSIONS: Postoperative electroretinogram abnormalities are consistently present in patients who have undergone N2O/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.

Adult↗
PubMed2004

Abnormalities of contrast sensitivity and electroretinogram following sevoflurane anaesthesia.

BACKGROUND AND OBJECTIVE: We tested the hypothesis that disturbances of the visual pathway following sevoflurane general anaesthesia (a) exist and persist even after clinical discharge criteria have been met and (b) are associated with decreased contrast sensitivity. METHODS: We performed pattern and full-field flash electroretinograms (ERG) in 10 unpremedicated ASA I patients who underwent nitrous oxide/sevoflurane anaesthesia. ERG and contrast sensitivity were recorded preoperatively, immediately after discharge from the recovery room and 2 h after discontinuation of sevoflurane. The time at which the Post Anaesthesia Discharge Score first exceeded 9 was also noted. Data were analysed using paired, one-tailed t-tests and Pearson's correlation coefficient. RESULTS: On the full-field photopic ERG, b-wave latency was greater at each postoperative time point (31.6+/-1.1 and 30.8+/-1.1 ms) compared to preoperatively (30.1+/-1.1 ms, P < 0.001 and P = 0.03, respectively). Oscillatory potential latencies were greater on discharge from the recovery room compared with preanaesthetic values (23.1+/-3.1 vs. 22.4+/-3.3 ms, P = 0.01) and returned to baseline by 2 h after emergence from anaesthesia. Also at 2 h after emergence from anaesthesia: (a) P50 latency on the pattern ERG was greater than at baseline (81.5+/-17.9 vs. 51.15+/-22.6ms, P = 0.004); (b) N95 amplitude was less compared to preanaesthetic values (2.6+/-0.5 vs. 3.3+/-0.4 microV, P = 0.003) and (c) contrast sensitivity was less compared to baseline values (349+/-153 vs. 404+/-140, P = 0.048). A positive correlation was demonstrated between contrast sensitivity and both N95 amplitude and b-wave latency (r = 0.99 and r = -0.55 at significance levels of P < 0.005 and P < 0.05, respectively). CONCLUSIONS: Postoperative ERG abnormalities and associated decreases in contrast sensitivity are consistently present in patients who have undergone nitrous oxide/sevoflurane anaesthesia. These abnormalities persist beyond the time at which standard clinical discharge criteria have been met.

Adult↗
PubMed2004

Perioperative plasma concentrations of stable nitric oxide products are predictive of cognitive dysfunction after laparoscopic cholecystectomy.

In this study our objectives were to determine the incidence of postoperative cognitive dysfunction (POCD) after laparoscopic cholecystectomy under sevoflurane anesthesia in patients aged >40 and <85 yr and to examine the associations between plasma concentrations of i) S-100beta protein and ii) stable nitric oxide (NO) products and POCD in this clinical setting. Neuropsychological tests were performed on 42 ASA physical status I-II patients the day before, and 4 days and 6 wk after surgery. Patient spouses (n = 13) were studied as controls. Cognitive dysfunction was defined as deficit in one or more cognitive domain(s). Serial measurements of serum concentrations of S-100beta protein and plasma concentrations of stable NO products (nitrate/nitrite, NOx) were performed perioperatively. Four days after surgery, new cognitive deficit was present in 16 (40%) patients and in 1 (7%) control subject (P = 0.01). Six weeks postoperatively, new cognitive deficit was present in 21 (53%) patients and 3 (23%) control subjects (P = 0.03). Compared with the "no deficit" group, patients who demonstrated a new cognitive deficit 4 days postoperatively had larger plasma NOx at each perioperative time point (P < 0.05 for each time point). Serum S-100beta protein concentrations were similar in the 2 groups. In conclusion, preoperative (and postoperative) plasma concentrations of stable NO products (but not S-100beta) are associated with early POCD. The former represents a potential biochemical predictor of POCD.

Adult↗
PubMed2003

Prediction of difficult tracheal intubation.

BACKGROUND AND OBJECTIVE: Preoperative bedside screening tests for difficult tracheal intubation may be neither sensitive nor specific enough for clinical use. The aim was to investigate if a combination of the Mallampati classification of the oropharyngeal view with either the thyromental or sternomental distance measurement improved the predictive value. METHODS: A total of 212 (109 male, 103 female) non-obstetric surgical patients, aged >18 yr, undergoing elective surgical procedures requiring tracheal intubation were assessed preoperatively with respect to the oropharyngeal (modified Mallampati) classification, thyromental and sternomental distances. An experienced anaesthetist, blinded to the preoperative airway assessment, performed laryngoscopy and graded the view according to Cormack and Lehane's classification. RESULTS: Twenty tracheal intubations (9%) were difficult as defined by a Cormack and Lehane Grade 3 or 4, or the requirement for a bougie in patients with Cormack and Lehane Grade 2. Used alone, the Mallampati oropharyngeal view, and thyromental and sternomental distances were associated with poor sensitivity, specificity and positive predictive values. Combining the Mallampati Class III or IV with either a thyromental distance <6.5cm or a sternomental distance <12.5cm decreased the sensitivity (from 40 to 25 and 20%, respectively), but maintained a negative predictive value of 93%. The specificity and positive predictive values increased from 89 and 27% respectively for Mallampati alone to 100%. CONCLUSIONS: The findings suggest that the Mallampati classification, in conjunction with measurement of the thyromental and sternomental distances, may be a useful routine screening test for preoperative prediction of difficult tracheal intubation.

Anesthesia, General↗
PubMed2003

Comparison of the effects of two intrathecal anaesthetic techniques for transurethral prostatectomy on haemodynamic and pulmonary function.

BACKGROUND AND OBJECTIVE: Transurethral prostatectomy is routinely performed under spinal anaesthesia. This technique can cause hypotension, which is particularly undesirable in the elderly. The objective was to compare spinal anaesthesia for transurethral prostatectomy using hyperbaric bupivacaine 15 mg (control group) and hyperbaric bupivacaine 10 mg (limiting spread by maintaining the upright position for 15 min) and fentanyl 25 microg (fentanyl group) in terms of haemodynamic and pulmonary function. METHODS: Thirty ASA I-III patients were randomly selected and underwent spinal anaesthesia with either hyperbaric bupivacaine 15 mg (immediately positioned supine) or hyperbaric bupivacaine 10 mg (upright for 15 min) and fentanyl 25 microg. RESULTS: The greatest changes in mean arterial pressure (P = 0.9), ephedrine requirements (P = 0.8) and mean maximum change in forced vital capacity (P = 0.5) were similar in both groups. CONCLUSIONS: The addition of fentanyl 25 microg to bupivacaine 10 mg and limiting the spread of the block does not improve either haemodynamic or pulmonary function compared with bupivacaine 15 mg in patients undergoing transurethral prostatectomy.

Adjuvants, Anesthesia↗
PubMed2002

A dedicated intravenous cannula for postoperative use effect on incidence and severity of phlebitis.

A prospective, randomised, controlled clinical study was performed to compare the incidence and severity of postoperative peripheral venous thrombophlebitis associated with a single intravenous cannula used for both intra-operative and postoperative purposes, and two cannulae, one used intra-operatively and the other postoperatively. Sixty American Society of Anaesthesiologists (ASA) physical status I or II patients aged 18-65 years undergoing elective surgery were studied. The technique of cannula insertion was standardised. After surgery, the cannulation sites were examined daily by a blinded investigator for the presence and severity of thrombophlebitis using the Baxter Scale. The two groups were similar in terms of age, gender, weight, type and duration of surgical procedures, and drugs and fluids administered both intra-operatively and postoperatively. The proportion of patients that developed phlebitis was significantly less in the two cannulae group (26.1%) than in the single cannula group (63.3%) (p < 0.0001). The severity of phlebitis was greater in the single cannula group than in the two cannulae group. These results indicate that the use of a dedicated cannula for postoperative use decreases the incidence and severity of postoperative, peripheral, cannula-related phlebitis.

Adult↗
PubMed2002

Effect of perioperative administration of dexketoprofen on opioid requirements and inflammatory response following elective hip arthroplasty.

BACKGROUND: In this double-blind, randomized, placebo-controlled trial, the safety and analgesic efficacy of perioperative dexketoprofen were evaluated. METHODS: Thirty ASA I or II patients undergoing elective hip arthroplasty were randomized to one of two groups. One group (D) received dexketoprofen 25 mg tds for 24 h before and 48 h after surgery; the second group (P) received placebo tablets at equivalent times. Hyperbaric 0.5% bupivacaine (17.5 mg if greater than 70 kg and 15 mg if less than 70 kg) and preservative-free morphine (0.6 mg) were administered intrathecally. Postoperatively, PCA was provided (bolus morphine sulphate 1 mg; lockout 5 min; no continuous infusion). RESULTS: The two groups were similar in terms of age, gender, weight, height, ASA class, duration of operation, and level of sensory block on arrival to the recovery room. Groups were also similar in terms of blood loss, transfusion requirements, ventilatory frequency, and haemodynamic variables. According to visual analogue pain scores patients in group D experienced less pain at 15 h (P=0.02) postoperatively. Cumulative morphine consumption was also less in group D compared with group P at 6 (0.06 (0.2) vs 0.85 (1.4) mg, P=0.04) and 48 h postoperatively (10.1 (8) vs 26.2 (20) mg, P<0.01). Plasma interleukin 6 concentrations increased postoperatively to a significantly lesser extent in group D than in group P (P=0.02). Nausea and vomiting were less (P<0.01) in group D compared with group P at 18 h postoperatively. Sedation scores were less (P=0.03) in group D. CONCLUSIONS: Perioperative administration of dexketoprofen 25 mg 8 hourly markedly improves analgesia and decreases opioid requirements (and associated adverse effects) following hip arthroplasty. It appears that this regimen decreases the postoperative pro-inflammatory response.

Aged↗
PubMed2001

The effect of lidocaine on neutrophil respiratory burst during induction of general anaesthesia and tracheal intubation.

BACKGROUND AND OBJECTIVE: Respiratory burst is an essential component of the neutrophil's biocidal function. In vitro, sodium thiopental, isoflurane and lidocaine each inhibit neutrophil respiratory burst. The objectives of this study were (a) to determine the effect of a standard clinical induction/tracheal intubation sequence on neutrophil respiratory burst and (b) to determine the effect of intravenous lidocaine administration during induction of anaesthesia on neutrophil respiratory burst. METHODS: Twenty ASA I and II patients, aged 18-60 years, undergoing elective surgery were studied. After induction of anaesthesia [fentanyl (2 microg kg-1), thiopental (4-6 mg kg-1), isoflurane (end-tidal concentration 0.5-1.5%) in nitrous oxide (66%) and oxygen], patients randomly received either lidocaine 1.5 mg kg-1 (group L) or 0.9% saline (group S) prior to tracheal intubation. Neutrophil respiratory burst was measured immediately prior to induction of anaesthesia, immediately before and 1 and 5 min after lidocaine/saline. RESULTS: Neutrophil respiratory burst decreased significantly after induction of anaesthesia in both groups [87.4 +/- 8.2% (group L) and 88.5 +/- 13.4% (group S) of preinduction level (P < 0.01 both groups)]. After intravenous lidocaine (but not saline) administration, neutrophil respiratory burst returned towards preinduction levels, both before (97.1 +/- 23.6%) and after (94.4 +/- 16.6%) tracheal intubation. CONCLUSION: Induction of anaesthesia and tracheal intubation using thiopentone and isoflurane, inhibit neutrophil respiratory burst. This effect may be diminished by the administration of lidocaine.

Adolescent↗
PubMed2001

Anaesthesia for children with epidermolysis bullosa: a review of 20 years' experience.

BACKGROUND AND OBJECTIVE: Epidermolysis bullosa is a rare, genetically determined disorder characterized by excessive susceptibility of the skin and mucosa to separate from the underlying tissues after mechanical trauma. Patients suffering from this disease may have multiple medical problems, but the risk of anaesthesia is attributed mainly to oropharyngeal involvement; airway management may be hazardous and preservation of mucosa and skin integrity problematical. There is a paucity of data in the literature concerning the perioperative management of children with epidermolysis bullosa. We present our experience of managing 54 general anaesthetics (and two local anaesthetics) over the past 20 years. METHODS: The case notes of 16 children with epidermolysis bullosa were reviewed. The children underwent surgical procedures under local or general anaesthesia over a 20-year period. RESULTS: Fifty-four general and two local anaesthetics were administered for 58 procedures in 10 children (mean age 12.6 years). Surgical procedures included oesophageal dilatation (24), insertion/revision of gastrostomy (16), dental procedures (10), hand surgery (2), skin biopsy (2) and others (4). Anaesthesia was induced by inhalation in 73.4% of patients and the airway was maintained with an endotracheal tube in 64.8%. Monitoring of anaesthesia was performed with pulse oximetry (89%), whereas electrocardiography and non-invasive blood pressure monitoring were used in 16.6% of cases each. The mean duration of anaesthesia was 64 min. Tracheal intubation was difficult in two of the five children who were intubated. Mucocutaneous blistering occurred in three children, otherwise there was no attributable morbidity. CONCLUSION: With maximal skin and mucous membrane protection, anaesthesia in children with epidermolysis bullosa may be undertaken with few sequelae.

Adolescent↗
PubMed2001

Postoperative changes in visual evoked potentials and cognitive function tests following sevoflurane anaesthesia.

We tested the hypothesis that minor disturbance of the visual pathway persists following general anaesthesia even when clinical discharge criteria are met. To test this, we measured visual evoked potentials (VEPs) in 13 ASA I or II patients who did not receive any pre-anaesthetic medication and underwent sevoflurane anaesthesia. VEPs were recorded on four occasions, before anaesthesia and at 30, 60, and 90 min after emergence from anaesthesia. Patients completed visual analogue scales (VAS) for sedation and anxiety, a Trieger Dot Test (TDT) and a Digit Symbol Substitution Test (DSST) immediately before each VEP recording. These results were compared using Student's t-test. P<0.05 was considered significant. VEP latency was prolonged (P<0.001) and amplitude diminished (P<0.05) at 30, 60, and 90 min after emergence from anaesthesia, when VAS scores for sedation and anxiety, TDT, and DSST had returned to pre-anaesthetic levels.

Adolescent↗