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Biomedical subjects

A T Bösenberg

Publications and source records attributed to A T Bösenberg.

17 recordsLinked to original sources
PubMed2002

Surface mapping of peripheral nerves in children with a nerve stimulator.

Defining anatomical landmarks may be difficult in the growing child. With the aid of a peripheral nerve stimulator, the path of many superficial peripheral nerves can be 'mapped' prior to skin penetration by stimulating the motor component of the peripheral nerve percutaneously with a 2-3.5 mA output. The required current will vary and is dependent upon the depth of the nerve and the moistness of the overlying skin. This 'nerve mapping technique' has proved particularly useful for brachial plexus, axillary, ulna and median nerve blocks in the upper limb and femoral and popliteal nerve blocks in the lower limb. It is a useful teaching tool and improves the success rate of peripheral nerve blocks in children of all ages.

Child↗
PubMed2001

Plasma concentrations of ropivacaine following a single-shot caudal block of 1, 2 or 3 mg/kg in children.

BACKGROUND: For documenting the properties of ropivacaine used for regional anaesthesia in children, the relationship between dose and resulting systemic exposure is essential. The aim of this pharmacokinetic part of a randomised, multicentre, double-blind study was to determine the free and total plasma levels of ropivacaine in children aged between 4 and 12 years following a single-shot caudal dose of 1, 2 or 3 mg/kg of ropivacaine for postoperative pain management. METHOD: Following induction of a standardised general anaesthetic (halothane; nitrous oxide: oxygen 60:40), a caudal block using 1 ml/kg ropivacaine in concentrations of 1, 2 or 3 mg/ml was performed in 43 ASA I children (body weight 12-25 kg) scheduled for elective inguinal surgery. Blood samples were collected prior to and 15, 30, 45, 60 and 240 min after placement of the caudal block for determination of total and free ropivacaine plasma concentrations. RESULTS: The peak plasma concentration of total ropivacaine, reached within 15-241 min after the block, increased in proportion to dose, with mean values at 0.27, 0.64 and 0.90 mg/l following 1, 2 and 3 mg/kg respectively. The peak plasma level of free ropivacaine also increased in a dose-proportional manner, with mean levels at 0.014, 0.030 and 0.042 mg/l. The highest individual peak plasma level of free ropivacaine was 0.070 mg/l, well below the threshold levels of CNS toxicity described in adults. No clinical signs of systemic toxicity were observed. CONCLUSION: Following single-shot caudal doses of 1-3 mg/kg in children up to 25 kg and aged between 4 and 12 years, plasma levels of free ropivacaine increase in proportion to dose and all were shown to be within safe limits.

Amides↗
PubMed2000

Congenital diaphragmatic hernia repair--impact of delayed surgery and epidural analgesia.

This study was undertaken to assess the impact on mortality and the need for postoperative ventilation of intra- and postoperative epidural analgesia and delayed surgery in neonates with congenital diaphragmatic hernia. The study was a retrospective chart review of 35 neonates with congenital diaphragmatic hernia treated in Durban between 1988 and 1993. The mortality rate was 30%, with too few patients having delayed surgery to demonstrate a benefit from this policy. Mortality and the requirement for postoperative ventilation were reduced in the epidural group. However, the patients with the worst prognosis all received general anaesthesia. The benefit of delaying surgery for congenital diaphragmatic hernia repair could not be demonstrated because of small numbers. Epidural analgesia appears to be a useful technique to reduce the need for postoperative ventilation following repair in lower-risk patients.

Analgesia, Epidural↗
PubMed1999

Management of sympathetic overactivity in tetanus with epidural bupivacaine and sufentanil: experience with 11 patients.

OBJECTIVE: To determine the efficacy and safety of epidural bupivacaine and sufentanil for the management of sympathetic overactivity in tetanus. DESIGN: Retrospective case review. SETTING: Sixteen-bed surgical intensive care unit in a tertiary care centre. PATIENTS: All patients referred to the unit during a 63-month period with the diagnosis of tetanus were included in the study. MEASUREMENTS AND MAIN RESULTS: All patients (n = 11) had severe tetanus and developed sympathetic overactivity, which was managed by epidural blockade. Three patients died, but there were no fatalities directly attributable to sympathetic overactivity. Before epidural blockade, the average difference between the mean maximum and mean minimum systolic blood pressures was 78 +/- 28 (so) mm Hg. After blockade, this difference was reduced to 38 +/- 15 (so) mm Hg (p < .0001). Similar significant reductions in diastolic blood pressure and heart rate were observed. The mean hourly infusion doses of bupivacaine and sufentanil were 17 mg and 21 microg, respectively. Midazolam was the principal adjunctive sedative agent and was used in all patients (mean dose, 9 mg/hr). Additional pharmacologic agents were necessary in two patients in whom epidural blockade alone was insufficient to control sympathetic overactivity. One patient developed renal failure and there were no instances of pneumothorax. One patient developed an epidural abscess of probable hematogenous origin, which was successfully treated without neurologic sequelae. CONCLUSIONS: Epidural blockade is effective in controlling sympathetic overactivity and the associated complications (renal failure, cardiac injury, and sudden death). Although a serious complication occurred in one patient, the efficacy of the technique deserves further validation.

Adolescent↗
PubMed1998

The respiratory effects of tramadol in children under halothane an anaesthesia.

In a randomised double-blind, placebo-controlled study, the respiratory effects of intravenous tramadol (1 mg or 2 mg.kg-1) were compared with intravenous pethidine 1 mg.kg-1 under halothane anaesthesia. Children, ASA 1-2 between 2 and 10 years, presenting for inguinal surgery were studied. Once a steady state for halothane was reached, baseline recordings of end-tidal carbon dioxide, oxygen saturation, respiratory rate, tidal volume, minute volume, blood pressure and pulse rate were recorded. Intravenous tramadol 1 mg.kg-1 (T1) or 2 mg.kg-1 (T2) or pethidine 1 mg.kg-1 (PE) or placebo (PL) was then given according to a computer-generated randomisation. Further sets of recordings were taken at 5-min intervals for 20 min prior to commencement of surgery. The rate of recovery was assessed according to Aldrete scoring and the time and need for further analgesia were noted. The postoperative pain intensity was scored by means of a five-point verbal rating scale hourly for 6 h. Eighty-eight children, 22 per group, were studied. The mean age, weight and height were similar in each group. There was a statistically significant difference between the maximum decrease in respiratory rate and increase in end-tidal carbon dioxide between group PE and groups T1/T2 (p < 0.001). Thirteen episodes of apnoea occurred in the PE group, 11 requiring naloxone. The mean respiratory rate was lowest 5 min after injection in all groups. There was a slow increase in respiratory rate until incision in groups T1 and T2. Respiratory rate remained almost unchanged in PL until incision. The decreases in respiratory rate were reflected by increases in end-tidal carbon dioxide, the highest being recorded in the PE group. A lower intensity of pain in the first 2 h was noted in the three opioid groups. During the first 6 h, the proportion of patients requiring a further dose of analgesia was highest in PL and lowest in T2. Tramadol appears safe for use in children.

Analgesics, Opioid↗
PubMed1998

Epidural analgesia for major neonatal surgery.

Safe effective analgesia for neonates undergoing major surgery remains a challenge particularly in institutions where resources are limited. The experience in the use of epidural analgesia in 240 neonates weighing between 0.9-5.8 kg body weight (lumbar n = 211, thoracic n = 29) is reviewed. Dural puncture (n = 1), convulsion (n = 1) and intravascular migration of catheter (n = 1) were the only complications. In all cases effective analgesia was established intraoperatively. Postoperatively analgesia was maintained by intermittent 'top-ups' (n = 170) and continuous infusion (n = 10). Skin epidural distance ranged between 3 and 12 mm (mean 6.0 +/- 1.7 mm) and did not correlate with the patients' weight. Patients remained haemodynamically stable except occasional bradycardia below 100 (n = 15) which was successfully managed with anticholinergics. The potential risks and benefits of epidural analgesia in this age group are discussed and arguments for intermittent 'top-up' doses rather than continuous infusions presented.

Analgesia, Epidural↗
PubMed1996

Attitudes towards parental presence at induction of anaesthesia.

OBJECTIVE: To determine the attitudes of South African anaesthetists with regard to allowing parents to be present during the induction of anaesthesia in children, and to determine the source and extent of resistance to this controversial practice. DESIGN: Questionnaire survey consisting of three parts and based on a previous study. SETTING: Southern Africa. PARTICIPANTS: All practising anaesthetists, specialist and non-specialist, on the mailing list of a major pharmaceutical company. RESULTS: Responses were obtained from 222 anaesthetists from 80 different localities in southern Africa. The majority of the respondents were specialist anaesthetists in private practice with between 5 and 15 years' experience. Of the respondents 55% agreed that it was acceptable to allow parents to be present at induction and that this did not compromise the child's safety; 117 claimed that there was resistance to the practice, perceiving the matron and nursing staff as the major source of resistance, both currently and in the past. Lack of facilities and loss of operating theatre sterility were cited as the main reasons for resistance. CONCLUSION: Although the practice is still controversial, the majority of anaesthetists who responded to the survey would be happy to allow parents to accompany children at induction. It should be catered for and encouraged according to certain guidelines.

Anesthesia↗
PubMed1995

Infraorbital nerve block in neonates for cleft lip repair: anatomical study and clinical application.

Infraorbital nerve block in neonates is not well described although it has been suggested that bilateral infraorbital nerve block is the local analgesic technique of choice for early repair of cleft lip. The purpose of this study was to determine the location of the infraorbital nerve in neonatal cadavers and to identify clinically useful landmarks. Thirty infraorbital nerves were identified in 15 neonatal cadavers with a mean weight of 2.85 (SD 0.32) kg (range 2.45-3.5 kg) via an upper buccal sulcus incision. The mean distance from the infraorbital nerve to the base of the alae nasi was 7.7 (SD 1.3) mm on the left and 7.5 (0.8) mm on the right. A line drawn from the angle of the mouth to the midpoint of the palpebral fissure measured 30.6 (1.9) mm (left) and 30.7 (1.8) mm (right). The nerve was situated approximately halfway along this line at a point 15.5 (1.5) mm (left) and 15.2 (1.4) mm (right) from the angle of the mouth. These measurements were used to perform bilateral infraorbital nerve blocks in four neonates undergoing cleft lip surgery under general anaesthesia, thereby providing analgesia with minimal risk of respiratory depression.

Bupivacaine↗
PubMed1995

Lower limb nerve blocks in children using unsheathed needles and a nerve stimulator.

The use of unsheathed non-insulated needles and a nerve stimulator as an aid to peripheral nerve blockade in children has received little attention in the literature. In order to assess the value of such a technique, a study was performed in children presenting for lower limb surgery with no contraindication to femoral and/or sciatic nerve block. Four hundred and eleven children, mean age 4.25 (SD 3.8) years and mean weight 16.8 (SD 9.4) kg, received a total of 883 peripheral nerve blocks: 419 femoral nerve blocks and 464 sciatic nerve blocks. One hundred and twenty six children were below one year of age. The current required to stimulate the more superficial femoral nerve ranged from 0.5-1.0 mA whilst for the deeper sciatic nerve ranged from 1.2-2.0 mA. Staff in training, with little or no experience of the technique, successfully performed 223 nerve blocks in 114 patients under the author's guidance. The overall success rate was 98%, the failures occurring early in the series.

Bupivacaine↗
PubMed1995

Skin-epidural distance in children.

The skin-epidural distance was measured in 274 children to assess the usefulness of 1 mm.kg-1 as a guideline. Children aged between 2 days and 16 years, weighing between 2 and 43 kg were investigated. Lumbar epidurals were performed under general anaesthesia using a midline approach in the L3-4 interspace with the patient in the lateral position. Good correlation between skin-epidural distance and age and weight was demonstrated. No statistical difference was shown when plotting the best fit regression line: skin-epidural distance (mm) = 0.8 weight (kg) + 3.93 (R2 = 0.74) and its 95% confidence limits and skin-epidural distance (mm) = weight (kg) for children between 6 months and 10 years. Poor correlation was noted below 6 months (n = 22) and over 10 years (n = 19). No dural puncture or bloody tap occurred. One mm.kg-1 body weight was shown to be a useful guideline for children between 6 months and 10 years of age.

Adolescent↗
PubMed1984

An evaluation of the pulse-contour method of measuring cardiac output.

The pulse-contour (PC) method continuously derives the cardiac output in litres per minute from the arterial pressure wave form by using a portable analogue computer. The reliability of the PC method in determining cardiac output was studied in 6 patients during anaesthetic induction for cardiac surgery. The results obtained with the PC method using the radial artery to register the arterial pulse wave were compared with cardiac output measurements using the more conventional thermodilution technique. The PC method would seem to offer a simple, clinically useful method for on-line monitoring of short-term variations in cardiac output.

Adult↗
PubMed1983

Trace element concentrations in commonly used intravenous fluids.

The concentrations of several essential trace elements in various intravenous fluids commonly used in South Africa were measured. With the exception of 4% human serum albumin and fresh freeze-dried plasma (FDP), intravenous fluids contained minimal amounts of essential trace elements. Although FDP contained significant quantities of zinc, copper, iron and chromium, the common practice of giving patients on total parenteral nutrition 1-2 units per week will not fulfil the recommended daily requirements. Additional trace element supplements should therefore be given intravenously to these patients.

Humans↗