[Awareness: a problem in paediatric anaesthesia?]

Intraoperative awareness has been reported to occur in 0.8-5.0% of paediatric patients undergoing anaesthesia and, therefore, seems to be more common than in adults (incidence 0.1-0.2%). In adult patients, the consequences of intraoperative awareness are well known and can be severe, in children, however, they have not yet been adequately studied. The causes for intraoperative awareness can be divided into three broad categories: First, no or only a light anaesthetic is given on purpose, second, an insufficient dose of an anaesthetic is given inadvertently, third, there is equipment malfunction or the anaesthesiologist makes an error. Unfortunately, especially in young children, painful interventions are still performed without adequate analgesia, e.g. awake intubation or fracture manipulation under midazolam sedation alone. The key issue is, however, that pharmacokinetics and pharmacodynamics change enormously from the 500 g preterm baby to the adolescent patient. Adequate dosing is much more difficult in paediatric patients compared to standard adult surgical patients. Solid knowledge of the pharmacokinetic and pharmacodynamic characteristics of commonly used drugs in different paediatric age groups, as well as aiming for perfection in daily care will help to reduce the incidence of awareness. Methods for monitoring the depth of hypnosis, e.g. the bispectral index, will be used increasingly, at least in children above 1 year of age. In addition to clinical parameters, they will hopefully help to further reduce the incidence of intraoperative awareness.

[Pain treatment in neonates, infants and children--is the current treatment sufficient?]

Paediatric patients quite often have to undergo painful or stressful procedures, e. g. blood sampling, dressing of wounds or removal of a drainage. The key problem is to decide if a child has pain or if there are other reasons for crying. Establishing a high standard in an institution requires regular evaluation and documentation of pain scores. For many clinical situations, clear and functioning concepts exist - we just have to use them. Unanswered questions are the evaluation of pain in small children, the side-effects of opioids, surgery involving the airways and the risk-benefit-ratio of certain techniques. Pain therapy after tonsillectomy is still troublesome: relevant postoperative pain occurs. Local infiltration of the tonsillar bed has no pre-emptive effect and only a minimal impact on the postoperative pain. Management relies on opioids, steroids and non-opioids. Non-steroidal anti-inflammatory drugs should not be used because of an increased risk of bleeding. Promising data have been reported on COX-2-blockers, but experience in children is still limited. Pain management after circumcision is relatively easy to perform. A conduction block with a long-acting local anaesthetic combined with one dose of a non-steroidal anti-inflammatory drug provides sufficient analgesia in over (2/3) of patients. Today, penile block is the standard of care and complications only rarely occur. However, despite successful pain prevention, circumcision remains a stressful procedure for the small patients. Pain treatment per se is not sufficient to relieve all the suffering connected with surgery in children. The concept of balanced analgesia is successful under many circumstances, but continuous efforts are needed to improve the management for difficult situations, e. g. tonsillectomy.

[Regional anesthesia in newborn infants, infants and children--what prerequisites must be met?]

In general, every anaesthetic technique should only be used with a given indication after a careful risk-benefit evaluation, when there are no contraindications and when the physician has sufficient knowledge and skill to safely perform the technique.

INDICATION

the great advantage of regional blocks is that they can be administered without the risks of opioids, e.g. respiratory depression, nausea, vomiting and delayed gastric emptying. Regional anaesthesia is rarely indicated instead of general anaesthesia: even ex-premature babies can safely undergo general anaesthesia supplemented with a regional block. Special risks occur when regional blocks are performed in anaesthetised children, and special care is needed. However, in contrast to adult practice, this is a generally accepted modality of paediatric anaesthesia worldwide. In addition, perfect analgesia may obscure the signs of compartment syndrome and beginning pressure sores. Preoperative evaluation: the preoperative evaluation relies mainly on the patient's history. Coagulation tests are not performed as routine screening. However, even with a careful history, bleeding disorders can be overlooked, especially in neonates and infants. Mastering the technique: caudal anaesthesia can be used for a large variety of interventions below the umbilicus; therefore, a sufficient caseload can be achieved by most anaesthetists, and the technique can be easily learned. It should belong, together with wound infiltration, ilioinguinal and penile block, to the armamentarium of all anaesthetists caring for children. However, regional blocks are of limited duration and are therefore only part of a concept of balanced analgesia, which also involves nonsteroidals, paracetamol and opioids.

[Paediatric anaesthesia: inhaled or intravenous technique?]

Total intravenous anaesthesia has recently gained more interest in paediatric anaesthesia. However, the global experience with children is limited, therefore, the knowledge acquired in adult practice is often applied uncritically to the paediatric patient. Induction of anaesthesia by mask is a widely used and generally accepted technique; it has gained even more popularity since the introduction of sevoflurane into clinical practice. This drug has markedly improved the safety because of the reduced cardiovascular side-effects. The availability of venous access is a prerequisite for intravenous induction. Pain on injection, bradycardia, and difficulties in dosing the individual patient are the main drawbacks. Inhaled anaesthetics allow to monitor breath by breath the individual pharmacokinetics. On the other hand, maintenance of anaesthesia by an intravenous infusion of propofol is mainly based on assumptions, even when the drug is administered by computer-controlled pumps. Large aberrations from the predicted values can occur in the individual patient. Intraoperative awareness is possible, however, its incidence is generally underestimated. Paravenous infusion and pump dysfunction are typical complications of an intravenous technique. A reduced incidence of postoperative vomiting and agitation are recognised advantages of an intravenous technique. Propofol-infusion-syndrome results from prolonged administration in children and in adults. It can even occur after the use of the substance for a few hours. The duration of a safe period for administration is completely unknown, especially for neonates and infants. In summary, both techniques can be used in children; both have advantages and drawbacks. Because the experience with small children is very limited, we have to re-evaluate our practice with a critical eye day by day.

Cardiac arrest in an infant with congenital adrenal hyperplasia

We report a 3-month-old boy who suffered an out-of-hospital cardiac arrest. During resuscitation, the medical team was informed that he was receiving hydrocortisone treatment. The possibility of adrenal insufficiency with hyperkalemic cardiac arrest prompted the administration of calcium, which resulted in the return of spontaneous circulation. The infant's diagnosis of congenital adrenal hyperplasia was not spontaneously mentioned by the parents. This case illustrates the importance of obtaining adequate parental information and considering hyperkalemia as a possible cause of cardiac arrest.

[Succinylcholine--update]

The action profile of succinylcholine is unmatched even 50 years after its introduction into anaesthestic practice. This is probably why succinylcholine, despite its many and partly life-threatening side-effects, is still considered to be indispensable by many anaesthetists and emergency doctors. The main indication for succinylcholine--the facilitation of endotracheal intubation in patients considered to be at an increased risk of aspiration of gastric fluid, e.g. patients undergoing a Caesarean section or presenting with an ileus--remains undisputed. Some of the side-effects of succinylcholine can be diminished by precurarisation. However, just like priming, this technique holds some considerable dangers (such as a clinically significant attenuation of the protective reflexes) and has become a matter of increasing controversy. Rocuronium (> or = 1 mg/kg) is currently the best alternative to succinylcholine for rapid sequence induction. The routine use of succinylcholine as a relaxant for intubation is questionable, mainly because there are a number of modern anaesthetic techniques (laryngeal mask airway) and new drugs (rocuronium, mivacurium, remifentanil) which make succinylcholine quite dispensable except for a few situations (e.g. re-positioning of fractures). In the case of an expected difficult airway no muscle relaxant should be given, because severe hypoxaemia in these patients probably can only be prevented by a professional airway management. Succinylcholine is no longer an option in elective paediatric anaesthesia. The drug, however, retains its value in critical situations where a rapid onset but a short duration of action is of prime importance.

[Postpartum neurologic complications following delivery with peridural analgesia. Case report with literature review]

Regional analgesia provides effective pain relief during delivery. Postpartal neurological deficits may be due to pressure of the fetal head on nerve structures at the pelvic rim or may be a complication of epidural analgesia. Nerve injuries due to spontaneous delivery and instrumental delivery are much more common than neurological deficits from epidural analgesia such as epidural hematoma or epidural abscess. The pattern of nerve damage is usually unilateral and non segmental. This case report describes the differential diagnosis of neurological deficit after spontaneous delivery under epidural analgesia and a discussion of the recent literature. Finally recommendations for the treatment of neurological deficits after delivery under epidural analgesia are presented.

[Tracheal rupture: delayed diagnosis with endobronchial intubation]

Tracheobroncheal rupture is a rare complication of intubation techniques using a stylet. In this case report the patient was intubated by an emergency physician in a preclinical setting after a motor vehicle accident. Iatrogenic tracheal laceration was masked by inappropriate position of the endobronchial tube. By chance ventilation was maintained to both lungs by flow through the Murphy's eye of the tube and the lumen of the tube. In correcting the deep tube position after a chest x-ray laceration of the trachea was unmasked and ventilation problems occurred immediately. The tube was replaced under fiberoptical control and the patient was managed for surgical repair using a jet ventilation technique. In this case two complications of endobronchial intubation occurred, but the deep tube placement opposed the effects of the tracheal laceration. This was probably life saving for the patient during emergency transfer by helicopter after the accident. The anaesthesiological management during tracheal repair is discussed.

Generating a learning curve for pediatric caudal epidural blocks: an empirical evaluation of technical skills in novice and experienced anesthetists

BACKGROUND AND OBJECTIVES

Learning curves for anesthesia procedures in adult patients have been determined, but no data are available on procedures in pediatric anesthesia. The aim of this study was to assess the number of caudal blocks needed to guarantee a high success rate in performing caudal epidural analgesia in children.

METHODS

At a teaching hospital, the technical skills of 7 residents in anesthesiology who performed caudal blocks were evaluated during 4 months using a standardized self-evaluation questionnaire. At the start of the study period, the residents had no prior experience in pediatric anesthesia or in performing caudal epidural blocks. All residents entered the pediatric rotation after a minimum of 1 year of training in adult general and regional anesthesia. The blocks were rated using a binary score. For comparison, the success rates of 8 experienced staff anesthesiologists were collected during the same period using the same self-evaluation questionnaire. Statistical analyses were performed by generating individual and institutional learning curves using the pooled data. The learning curves were calculated with the aid of a least-square fit model and 95% confidence intervals were estimated by a Monte Carlo procedure with a bootstrap technique.

RESULTS

The success rate of residents was 80% after 32 procedures (95% confidence interval of 0.59 to 1.00). The pooled success rate of the staff anesthesiologists was 0.73 (mean) with a standard deviation of 0.45, which was not statistically different from the success rate of the residents.

CONCLUSION

High success rates in performing caudal anesthesia in pediatric patients can be acquired after a limited number of cases. Success rates of residents learning this procedure are comparable to the results of staff anesthesiologists.

Postoperative pain management in infants and children: new developments

The elimination of pain should be of outstanding importance for all people caring for children. A concept of balanced analgesia including non-steroidal anti-inflammatory drugs, opioids and local anaesthetics is widely accepted. This review focuses on extending analgesia beyond the immediate postoperative period, the understanding of pharmacokinetic-pharmacodynamic interactions of paracetamol, the side-effects of opioids during patient-controlled administration, and the position of ropivacaine in paediatric pain management. For the majority of clinical situations, however, we already have established and functioning concepts for analgesia; we only have to use them!

Blockade of the sciatic nerve in the popliteal fossa: a system for standardization in children

The sciatic nerve can be blocked at different levels, providing excellent surgical and postoperative anesthesia and analgesia. We report a series of 50 blocks performed via the popliteal fossa in children. Localization of either the tibial or peroneal nerve was facilitated by a nerve stimulator. The local anesthetic solution was injected at the point where nerve stimulation was achieved with 0.4 mA at an impulse width of 1.0 ms. The depth of insertion of the stimulation cannula correlated with the age, weight, and height of the patients. The best predictor for depth of insertion was the patient's weight. The minimal depth of insertion was 13 mm. No failure of blockade was seen in this case series. Blockade of the sciatic nerve can easily be performed in the popliteal fossa even in small children.

IMPLICATIONS

Blockade of the sciatic nerve can easily be performed in the popliteal fossa even in small children. The depth of insertion of the stimulation cannula can best be estimated according to the weight of the patient. The minimal depth required was 13 mm.

[Acute lumbar disk displacement with nerve root compression. Indications for peridural steroid injection]

The rationale and indication, but also the efficacy and limitation of lumbar epidural corticosteroid injection in patients suffering from acute lumbosacral radicular pain are explained. Epidural administration of corticosteroids with longterm effect and bupivacaine by a translumbar approach in patients suffering from acute low back pain and sciatica causes an immediate, persistent pain relief and a more prompt regression of nerve root compression compared to patients just treated by bed rest and analgesics. The state of the art is based on recent meta-analyses and the understanding of the pathophysiology of discal hernia which includes inflammation. Contemporary concepts and data from recent reviews are summarized to elucidate current recommendations and suggestions for the management of patients with acute sciatica. The postulate of an application performed by an experienced anaesthesiologist is stressed. Advantages of this invasive form of therapy include reduction of addictive analgesic drugs, decreased time of absolute immobilisation, respectively strict bed rest, and of hospitalisation.

[Value of monitoring muscle relaxation]

INDICATION

Sensitivity to neuromuscular blocking agents differs between individuals, and residual neuromuscular blockade is a common postoperative problem. Clinical signs such as head lift, hand grip, and inspiratory force are suitable means of showing residual blockade. However, an awake and cooperative patient is needed. Therefore, in clinical practice it is advantageous to use the responses evoked by a nerve stimulator.

SITES OF NERVE STIMULATION AND DIFFERING MUSCLE RESPONSE

In clinical anesthesia, the ulnar nerve is the most popular site. The response is evaluated by feeling the contractions of the adductor pollicis muscle. This muscle shows a slow onset of blockade and is highly sensitive to neuromuscular blocking agents. Therefore, the chance of overdosing the patient is decreased and during recovery additional safety is gained, as it can be safely assumed that at the time of normalization of the thumb twitches no residual blockade exists in the diaphragm or larynx. On the other hand, absent twitches of the adductor pollicis using train-of-four stimulation do not preclude intraoperative activity of more resistant muscles such as the diaphragm.

RECORDING OF EVOKED RESPONSES AND PATTERNS OF NERVE STIMULATION

In clinical anesthesia, tactile evaluation of the muscle response is the usual method. Mechanomyography (Myograph) with a force transducer is used as the reference standard. This method, as well as the measurement of acceleration (Accelograph, TOF-Guard) and electromyography (Relaxograph) are mainly tools for teaching and research. Different patterns of nerve stimulation are used: during induction, single-twitch stimulation at 1Hz; during profound blockade, post-tetanic count stimulation (PTC); surgical blockade is evaluated using train-of-four stimulation (TOF); and recovery is followed by double-burst stimulation (DBS). Using simple train-of-four stimulation during recovery, a device is needed with a registering capacity to accurately determine a TOF-ratio > 0.7.

CONCLUSIONS

Relaxometry allows monitoring of neuromuscular function independently of the patient's cooperation, and should be standard. In the intensive care unit, relaxometry helps to minimize the risk of overdosing. However, muscular weakness can persist despite adequate drug dosage. Relaxometry is only part one of a concept. Intubating and operating conditions are highly dependent on the depth of anesthesia, and the risk of postoperative residual blockade can be minimized by using short or medium action drugs.

Incremental dosing versus single-dose spinal anesthesia and hemodynamic stability

We compared the hemodynamic stability after spinal anesthesia with two different dosing regimens in the elderly. Fifty patients, all older than 60 yr and scheduled for elective knee or hip surgery were assigned to two groups. After administration of 10 mL/kg of lactated Ringer's solution (RL) intravenously (i.v.) in the first group, we performed a continuous spinal anesthesia (CSA) by means of a 28-gauge catheter through which repetitive injections of 2.5-5 mg of plain bupivacaine 0.5% were given. In the other group, a single-dose spinal anesthesia (SS) with 20 mg of the same local anesthetic (LA) was carried out. Noninvasive mean arterial pressure (MAP), heart rate, and levels of analgesia were measured. To maintain MAP within 25% of initial value, the patients received additional i.v. fluids (RL) as first measure. When MAP could not be maintained despite hydration, incremental doses of ephedrine were given i.v. Six patients in the CSA group and 17 in the SS group developed a level of anesthesia higher than T6 (P < 0.01). In the SS group more fluid was needed (792 vs 388 ml) than in the CSA group (P < 0.01). Moreover, more patients of the SS group (11 vs 4) required ephedrine (P < 0.05). We conclude that CSA produces reliable and predictable analgesia for lower limb surgery with less need for correction of hemodynamic changes compared to SS.

Postoperative vomiting in children. A persisting unsolved problem

Nausea and vomiting after anaesthesia and surgery in children remains a major problem. The following survey studies the frequency of postoperative vomiting and relates it to the anaesthetic technique, the surgical procedure, and postoperative analgesia. During one year, September 1989 until September 1990, 2370 surgical patients requiring anaesthesia were studied prospectively with the following protocol: 1) patient data, surgery and anaesthesia technique; and 2) postoperative follow-up were registered. Outpatients were followed up by telephone. The overall incidence of vomiting was 19.5%, which was lower than in other studies. An increased incidence of vomiting was found in children over 2 years of age, after certain operative procedures, and after general anaesthesia. Furthermore, postoperative opioid administration on the ward increased the risk of vomiting. Despite the low overall incidence of vomiting in our study, we still found a high frequency after certain surgical procedures. The use of regional anaesthesia, prophylactic antiemetic medication, and the introduction of new anaesthetics, may help to reduce the sometimes high incidence of postoperative nausea and vomiting in paediatric patients.

[Brief narcosis with propofol/ketamine for administering retrobulbar anesthesia]

BACKGROUND

Eye surgery is performed under local anesthesia in more than 90% of the cases. While injecting the local anesthetics a deep sedation is desired. During surgery however the patient should be cooperative, such as to avoid inadvertent movements. We routinely perform local anesthesia (retrobulbar injection and van Lint block) under intravenous anesthesia with propofol (Disoprivan) and ketamine (Ketalar, Ketanest).

PATIENTS AND METHODS

To control safety and efficacy of this method a prospective study was performed including 100 consecutive patients. The results were to be compared with an earlier study where 35 Patients received midazolam (Dormicum) and alfentanil (Rapifen) as sedation. The actual protocol included the following points: 1. Personal judgement of the patient. 2. Conditions to perform the retrobulbar injection, 3. Intraoperative conditions and additional sedation, 4. Pulse, blood pressure and blood oxygen concentration, 5. Complications

RESULTS

> 95% of the patients had a total amnesia of the injection of local anesthetics. Retrobulbar injection is comfortable (96%), but may be difficult in patients with a narrow orbit and exotropia (4%). Intraoperative conditions were noted as good in 97%. Additional sedation during surgery was necessary in 3%. Blood pressure and pulse remained stable. Blood oxygen concentration showed a tendency to sink during intravenous anesthesia. This could be managed easily by additional oxygen via face mask if necessary. Postoperative emesis was noted in 3%. No further ocular complications occurred that might be related to the anesthetic management. In an earlier study including 35 Patients under comparable conditions we used midazolam and alfentanil for sedation. The results were similar. Midazolam and alfentanil were then used in over 2000 operations. Often the patients were deeply sedated and asleep during surgery which meant a potential risk of a sudden awakening and moving the head inadvertently. Occasionally paradoxical reactions occurred after midazolam.

CONCLUSIONS

Using propofol and ketamine while performing the local anesthesia the patients are awake but relaxed and cooperative during surgery. This method has now been used routinely in over 1000 cases. It has proved to be clinically safe and efficient. It offers the surgeon good working conditions and is well tolerated by the patients, reducing their preoperative and perioperative anxieties.

[Paraplegia following pneumonectomy. An anesthesiological or a surgical complication?]

A case of postoperative paraplegia after pneumonectomy of the left lung is presented. The patient received thoracic epidural anaesthesia for postoperative pain relief. The etiological role of epidural blockade in paraplegia is discussed. After consideration of differential diagnosis, postpneumonectomy paraplegia was diagnosed. The neurological sequelae were caused when the arterial blood supply to the spinal cord was compromised during surgery. However, to rule out epidural hematoma in such patients, a CAT scan of the spine must be performed immediately.

[Continuous spinal anesthesia using bupivacaine. Report of experiences]

Continuous spinal anesthesia has not yet found general acceptance, although it is a simple and efficient method. Its main advantage is allowing a reliable block to be built up step by step while carefully monitoring the cardiovascular changes. Postspinal headache can be avoided by restricting the use of elderly patients. At our institution, continuous spinal anesthesia has been administered to geriatric high-risk patients for more than 6 years. We report our experience from the year 1986. PATIENTS AND METHODS. Over a 1-year period continuous spinal anesthesia was used for 157 patients with a mean age of 80.4 years (Fig. 1). Of these patients 111 (70.7%) were classified as ASA 3-5 (Fig. 2). In 2 cases a myocardial infarction dated back only 4 and 11 days. The most common indications for surgery were hip fractures (97, 61.8%) and vascular occlusions (37, 23.6%). An 18G Tuohy needle was used for lumbar puncture. The catheter (Portex minipack) was advanced 3-6 cm into the subarachnoid space. Plain bupivacaine 0.5% was injected in small increments until the desired block level was achieved. The catheters were removed immediately after surgery. RESULTS. In 155 of 157 cases surgery was completed under regional anesthesia. Two patients had to be intubated intraoperatively (1 unexpected laparatomy during vascular surgery, 1 with insufficient block for lumbar sympathectomy). The main technical problem was impossibility to advance the catheter into the subarachnoid space despite free flow of CSF (5 cases). For these patients single-shot spinal (4 cases) or epidural anesthesia (1 case) was used.(ABSTRACT TRUNCATED AT 250 WORDS)

[A complication of continuous blockade of the femoral nerve]

The continuous femoral nerve block is an effective method of analgesia after knee surgery. We report a case with acute compression syndrome of the femoral nerve caused by a subfascial hematoma. The symptoms developed 30 h after induction of the block. Immediate decompression brought pain relief and prevented permanent neurologic sequelae.

Cardiomyopathy in cystic fibrosis: lymphoedema of the heart with focal myocardial fibrosis

Cardiomyopathy in cystic fibrosis (CF) is an unusual heart disease, mainly characterized by a multifocal fibrosis of the left ventricle. The disorder chiefly occurs in the age group of 1-2 years and leads to fatal cardiac failure. The causal pathogenesis of the disease has not been discovered up to now. In two cases of CF-associated cardiomyopathy we found an oedema (mainly lymphoedema) of the myo- and epicardium and a lymph stasis in lymph vessels and lymph nodes of the heart. Based on a comparative study using animal models we speculate that a) CF may be complicated by a disorder of cardiac lymph circulation, and b) chronic cardiac lymphoedema of the heart in CF can cause focal myocardial damage with fibrosis.