Temporal summation during extradural anaesthesia

We have investigated in 10 patients the effect of extradural anaesthesia on temporal summation by comparing pain thresholds to single and repeated (five impulses at 2 Hz) electrical stimuli and compared these tests with pinprick and cold stimulation. Bupivacaine 0.5% (20 ml) was injected at L2-3. After extradural anaesthesia the threshold to repeated stimuli was significantly lower than the threshold to single stimuli (P = 0.0007). Nine patients lost cold sensation and 10 patients pinprick sensation. Pain to single electrical stimulation disappeared in six patients and pain to repeated electrical stimulation in one. Pain may be evoked by temporal summation of repeated electrical stimuli even when pinprick sensation, cold sensation and pain to single electrical stimuli are inhibited. Thus temporal summation should be taken into consideration when extradural analgesia is assessed.      

Spinal anaesthesia

Spinal anaesthesia involves the injection of local anaesthetic solution into the intrathecal space. It is a widely practiced anaesthetic technique that can provide surgical anaesthesia for procedures below the umbilicus. Due to the proximity of the central nervous system, safe practice is of paramount importance and requires a good understanding of relevant anatomy, physiology and pharmacology. Complications are rare but need to be recognized and managed rapidly and appropriately.     

Spinal anaesthesia

In spinal anaesthesia, surgical analgesia and in most cases motor block is achieved by injecting one or more drugs into the cerebrospinal fluid. As one of the earliest methods of anaesthesia it was introduced into clinical practice in the late nineteenth century. Although later on it was more or less replaced by "modern" general anaesthesia, it has regained popularity due to its benefits for certain patient populations. In spite of being a technically simple procedure, performing spinal anaesthesia requires a sound knowledge of applied physiology and pharmacology, especially in high-risk groups such as pregnant women or former preterm babies. For some patients even under anticoagulant therapy, spinal anaesthesia might be the best option, considering the individual risk of alternative methods.     

Spinal anaesthesia

Spinal anaesthesia is the injection of local anaesthetic into the subarachnoid space. It is a simple technique that can be used to provide surgical anaesthesia for procedures involving the abdomen, pelvis and lower limbs. To perform the technique safely it is important to understand the physiology of the block and the pharmacology of the drugs commonly used. Although serious complications are rare, they must be recognized and managed quickly.     

Spinal anaesthesia

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

Spinal anaesthesia

Spinal anaesthesia involves the injection of local anaesthetic solution into the intrathecal space. It is a widely practised anaesthetic technique that can provide surgical anaesthesia for procedures below the umbilicus. Due to the proximity of the central nervous system, safe practice is of paramount importance and requires a good understanding of relevant anatomy, physiology and pharmacology. Complications are rare but need to be recognized and managed rapidly and appropriately.     

Spinal epidural anaesthesia

We present our experience with a new combined spinal epidural system through which regional anaesthesia was performed in 30 male patients undergoing suprapubic prostatectomy. The technique consists of two needles, a 17 G Tuohy needle with a hole in its distal curve (back eye) and a 29 G spinal needle which is passed through the back eye before being introduced into the subarachnoid space. We found the back eye combined spinal-epidural system effective and simple to use. The Tuohy needle with its back eye did not impede insertion of the epidural catheter and was a suitable introducer for the thin 29 G spinal needle.     

Spinal anaesthesia in paediatrics

The use of spinal anaesthesia in children has been primarily limited to situations in which general anaesthesia was considered to pose an excessive risk. The ex-premature infant and the neurologically impaired child account for the majority of spinal anaesthetics used today. Spinal anaesthesia, compared with general anaesthesia, in the ex-premature infant undergoing inguinal hernia repair has decreased postoperative respiratory complications (e.g. apnoeic events, prolonged mechanical ventilation). Hyperbaric tetracaine and bupivacaine solutions are the local anaesthetics of choice. Haemodynamic stability is well preserved in neonates having spinal anaesthesia. Advances in spinal needle design have decreased the incidence of postdural puncture headache (PDPH). Catastrophic events have occurred with neuraxial techniques. Care must be taken in evaluating the relative risks of anaesthetic approaches in infants and children.     

Spinal anaesthesia in obstetrics

Spinal anaethesia has been used since the 1800s but, due to a number of complications, the popularity of this technique has waxed and waned. In the 1950s, it was the most widely used method of anaesthesia and analgesia in obstetrics but it fell out of fashion with the arrival of the epidural technique which allowed a continuous method of delivering analgesia with relatively few complications. Hypotension and the high incidence of postdural puncture headaches were two reasons for the decline in the popularity of spinal anaesthesia in the young, otherwise healthy pregnant population. With the development of newer needles and bevel designs and methods whereby the incidence of hypotension can be minimized, spinal anaesthesia is making a reappearance in obstetrical anaesthesia spheres. The purpose of this article is to review the history, effects, technique, indications, contraindications and complications of this method of anaesthesia as it applies to the obstetrical patient. A cause de certaines complications, la rachianesthésie qui avait été déjà utilisée depuis la fin du siècle dernier, a connu des bonds et des chutes de popularité. Dans les années 1950, elle était la forme d’analgésie et d’anesthésie la répandue en obstétrique. Elle a cessé d’être à la mode avec l’arrivée de l’épidurale qui permettait d’administrer l’anesthésie en mode continu avec un minimum de complications. L’hypotension et l’incidence élevée de céphalée post-rachidienne ont constitué les deux raisons du déclin de la rachianesthésie pour le bénéfice d’une population de femmes jeunes et biens portantes. Avec le développement de nouvelles aiguilles et de nouveau modèles de pointes, et de méthodes qui minimisent l’incidence de l’hypotension, la rachianesthésie effectue un retour en anesthésie obstétricale. L’objectif de cet article est de rappeler l’histoire, les effets, les techniques, les indications, les contrindications et les complications de cette technique anesthésique appliquée à l’obstétrique.     

Spinal anaesthesia for obstetrics

For a long time, epidural anaesthesia has been considered the method of choice for Caesarean delivery. The increased incidence of hypotension by the rapid onset of sympathetic blockade under spinal anaesthesia has been associated with a decline in uteroplacental blood flow and significant fetal acidosis, which may compromise neonatal well-being. Nevertheless, a decrease in fetal pH has not been shown to reduce neonatal Apgar or neurobehavioural assessment scores. Maternal blood pressure can be preserved with little side effects with low doses of vasopressors. On the other hand, spinal anaesthesia conveys significant advantages over epidural anaesthesia such as the simplicity of its use and the speed of onset, which allows neuraxial anaesthesia in urgent Caesarean sections and thus reduces the necessity for general anaesthesia. The small doses of local anaesthetics required to perform spinal anaesthesia reduce the risks of systemic toxicity to zero. Spinal anaesthesia is now considered the method of choice for urgent Caesarean section. The use of intrathecal opioids has profoundly changed the quality of spinal anaesthesia, with improved analgesia, a reduction in local anaesthetic requirements and shorter duration of motor blockade. Preliminary studies indicate that spinal anaesthesia may be safely performed in patients with severe pre-eclampsia, in whom spinal anaesthesia was previously considered contraindicated.     

Spinal anaesthesia and dysfibrinogenaemia

We report the case of a 34-year-old woman who presented to the delivery unit at 36 weeks' gestation with spontaneous rupture of membranes. She had a triplet pregnancy following in vitro fertilisation. An elective caesarean section was performed under spinal anaesthesia 4h after admission. The patient had a massive postpartum haemorrhage in the recovery area at which time she mentioned that she was known to have 'low fibrinogen'. Further investigation showed that she suffered from dysfibrinogenaemia, as did several members of her family. We can find no reported cases of the use of central neural blockade in a patient with untreated dysfibrinogenaemia. Central neural blockade is often considered contraindicated in patients with disorders of fibrinogen; there were fortunately no neurological sequelae following spinal anaesthesia in this patient.     

Spinal anaesthesia for outpatient surgery

Spinal anaesthesia in the outpatient is characterized by rapid onset and offset, easy administration, minimal expense, and minimal side effects or complications. Spinal anaesthesia offers advantages for outpatient lower extremity, perineal, and many abdominal and gynaecological procedures. Development of small-gauge, pencil-point needles are responsible for the success of outpatient spinal anaesthesia with acceptable rates (0-2%) of postdural puncture headache (PDPH). Compared with peripheral nerve blocks, spinal anaesthesia has a more predictable offset. There are many possible choices of local anaesthetics for outpatient spinal anaesthesia. These include lidocaine, prilocaine, mepivacaine and small doses of bupivacaine. Meperidine has local anaesthetic properties in addition to its opiate properties. It has been used as the sole intrathecal agent for spinal anaesthesia but has no real advantages over lidocaine. Mepivacaine and lidocaine have each been associated with transient neurological symptoms (TNS) following intrathecal administration. This has stimulated development of alternative agents, including combinations of local anaesthetics and opioids. Lidocaine remains the most useful agent for outpatient spinal anaesthesia. For longer procedures, mepivacaine is an excellent spinal anaesthetic agent. Attention to technique, reduction of dose and addition of fentanyl to lidocaine result in effective spinal anaesthesia with rapid recovery and a low incidence of significant side effects or complications.     

Spinal anaesthesia for spinal surgery

Spinal anaesthesia for spinal surgery is becoming increasingly more popular because this anaesthetic technique allows the patient to self-position and avoid neurological injury that may occur with prone positioning under general anaesthesia. Spinal anaesthesia reduces intraoperative surgical blood loss, improves perioperative haemodynamic stability and reduces pain in the immediate postoperative period. This leads to a reduced need for analgesics and a reduction in the incidence of nausea and vomiting in the postoperative setting. Spinal anaesthesia for lumbar spine surgery also decreases the incidence of lower extremity thrombo-embolic complications and does not increase the occurrence of problems with micturition. These benefits increase the patient's satisfaction, and they expedite discharge of the patient from the hospital. Combination anaesthetic techniques, using both subarachnoid and epidural dosing schemes, may be beneficial for improving postoperative pain control and add further to the benefit of spinal anaesthesia for lumbar spine surgical procedures.     

Spinal anaesthesia and spina-bifida occulta

We describe a patient with unexpected spina bifida who underwent spinal anaesthesia for trans-urethral resection of prostate and developed serious neurological signs. An unexpected spinal tumour was removed two weeks later. This report demonstrates that not all neurological problems associated with spinal anaesthesia should be blamed on the technique.     

Spinal anaesthesia in the neonate

Postoperative apnoea in ex-premature infants is inversely proportional to gestational age at birth and postmenstrual age (PMA). Spinal anaesthesia is an important technique in ex-premature infants as it reduces the risk of postoperative apnoea, provided intra-operative sedation is avoided. Recent studies have provided more data on recommended doses of local anaesthetics for infant spinal anaesthesia as well as adjuvants used to prolong the duration of surgical anaesthesia. Spinal anaesthesia is also used for surgical procedures other than inguinal hernia repair. There are a variety of reasons why awake regional is not the preferred technique for ex-premature infants undergoing lower abdominal surgery in many centres, and there is also controversy over the appropriate anaesthetic technique for outpatient surgery in infants <60 weeks PMA. A pragmatic decision analysis on the selection of anaesthetic techniques for inguinal hernia repair in infants is presented.