Quality improvement of regional anaesthesia
The title and objective of this doctoral thesis is “Quality Improvement of Regional Anaesthesia”. Therefore, we conducted research projects that may have an important impact on patient outcome and as such potentially change clinical practice.
We investigated the role of dexamethasone as an additive to LA in regional anaesthesia techniques. In daily practice, anaesthesiologists and surgeons are often confronted with the fact that a longer duration of analgesia is required than what can be offered with long-acting LA.
An excellent example to demonstrate the importance of long-lasting analgesia is shoulder surgery. Owing to the comprehensive innervation of the shoulder joint, shoulder surgery, even performed arthroscopically, results in severe postoperative pain lasting up to 24 hours. Therefore, interscalene brachial plexus blocks (ISB) have become the “gold standard” to treat and prevent postoperative pain. Without ISB, patients will require large quantities of opioids to provide adequate pain relief. The proficient use of opioids will inevitably lead to a high incidence of side-effects such as excessive sedation, respiratory depression, pruritus and postoperative nausea and vomiting. Arthroscopic shoulder surgery is not associated with excessive blood loss or large volume shifts, postoperative bowel dysfunction or other typical problems preventing same day discharge. Therefore, patients can be easily treated in an ambulatory setting, except if pain or opioid related side-effects prohibit an early discharge. With an ISB, analgesia after shoulder surgery is excellent, allowing same day hospital discharge. However, patients will be confronted with pain once the ISB wears off. This will typically happen at home, unfortunately often in the middle of the night. This results in low levels of patient satisfaction and even hospital readmissions for proper pain management. To avoid such readmissions, it is extremely important to provide long lasting analgesia allowing patients to have a painfree first postoperative night. With perineural dexamethasone, this goal can be achieved as it will typically prolong analgesia with 8 hours, extending the analgesic duration to almost 24 hours. Nevertheless, anaesthesiologists are reluctant to use perineural dexamethasone. This is mainly because of fear of litigation in case of post PNB injury that may be associated with the “off-label” administration of dexamethasone.
We performed a prospective randomized controlled trial to demonstrate that i.v. dexamethasone provides a similar prolongation of analgesia as perineural dexamethasone. Owing to the results of this study, anesthesiologist are able to provide similar quality of analgesia as with perineural dexamethasone but without the associated risks of possible neurotoxicity.
We also performed a prospective randomized controlled trial to demonstrate that a dose of 2.5 mg i.v. dexamethasone significantly prolonged duration of analgesia after ISB. Lowering the dose of dexamethasone without significant reduction of efficacy is important, especially for those patients at risk for dexamethasone associated side-effects. In diabetic patients, hyperglycemia could be provoked by the surgically induced stress response but also the perioperative glucocorticoid administration. To avoid this adverse effect, diabetes has been an exclusion criterion in our studies. However, in our clinical practice, with almost 3000 PNBs annually, we did observe severe postoperative hyperglycemia (>600mg/dL) in diabetic patients after administration of 10 mg dexamethasone. As was demonstrated with our research, a dose of 2.5 mg dexamethasone did prolong duration of analgesia with 5 hours. Again, this is important for clinical practice: reducing the dose of i.v. dexamethasone to 2.5 mg might reduce the incidence of glycemic dysregulation in diabetic patients, but still preserve the analgesic potential of dexamethasone.
Furthermore, we investigated the effect of epidural and intravenous dexamethasone on analgesia after Caesarean section. Nowadays, spinal anaesthesia is the “gold standard” for elective Caesarean section. Conventional methods to prolong postoperative analgesia such as intrathecal opioids and epidural catheters all come with unfavourable effects that negatively impact an early recovery. If dexamethasone, regardless of route of administration, would provide long lasting analgesia without adverse effects, it would greatly improve the outcome for both mother and newborn. Unfortunately, our prospective, randomized controlled trial could not demonstrate a significant effect of either intravenous or epidural dexamethasone on postoperative outcome.
In Part 2, we investigated factors influencing the success of different plane blocks.
First, we investigated the role of a pneumoperitoneum on the spread of LA with a midaxillary TAP block. This is clinically important as spread of LA is one of the most important determinants of the clinical success of TAP blocks. We demonstrated that the change of abdominal geometry caused by a pneumoperitoneum does not influence the spread of LA (Chapter 6). Furthermore, we also demonstrated that spread beyond the the aponeurosis of the abdominal wall muscles did not occur regardless of timing of the TAP block. Therefore, based on our research, we concluded that if posterior spread is desired, anaesthesiologists should not rely on the effect of a pneumoperitoneum but rather use a different approach such as the Transmuscular Quadratus Lumborum block.
Second, we investigated the role of a new approach to the iliac fascia. Since the early seventies, anaesthesiologists have explored different anterior approaches of the lumbar plexus. As was demonstrated by radiological and clinical research, both the so called 3-in-1 block and the transverse, infra-inguinal FICB do not reliably block the femoral, obturator and lateral femoral cutaneous nerve. Thus far, the longitudinal supra-inguinal approach to the fascia iliaca was only described in a cadaver study. We performed a prospective, randomized controlled trial demonstrating that this approach significantly decreases morphine consumption and pain scores after THA, offering evidence to clinicians who want to adopt this new approach. As this new approach requires large doses of LAs to be successful, we measured serial total and free ropivacaine serum levels at different time points. As none of the measurements reached the threshold for LAST, we concluded that the longitudinal supra-inguinal approach is not only effective but also safe.