From cell to nerve in regional anesthesia

This thesis addresses questions in the realm of regional anesthesia, spanning diverse topics from diabetes mellitus as a co-morbidity to the application of stem cells in this field. The first part focuses on the clinical relevance of diabetes mellitus, revealing altered responses to regional anesthesia in diabetic rodents. Pharmacodynamic and pharmacokinetic aspects are investigated in sciatic nerve blocks in diabetic rats, shedding light on heightened responsiveness and prolonged retention of local anesthetics in diabetic neuropathic nerves. Findings of the applied anatomy of the saphenous and obturator nerves for nerve blocks provide valuable insights into the negligible involvement of both nerves in the corresponding blocks. The minimal volume of local anesthetic required for a saphenous nerve block is determined, while we compare the femoral nerve block and adductor canal block in anterior cruciate ligament surgery. The final part of this thesis introduces stem cells to regional anesthesia research. The potential of induced pluripotent stem cells (iPSCs) is discussed as a model for pain signaling, emphasizing their role in pharmaceutical research. We present a functional study with iPSC-derived dorsal root ganglion nociceptors, demonstrating their responsiveness to lidocaine and proposing a model for comprehensive preclinical investigations of analgesics

From cell to nerve in regional anesthesia

This thesis addresses questions in the realm of regional anesthesia, spanning diverse topics from diabetes mellitus as a co-morbidity to the application of stem cells in this field. The first part focuses on the clinical relevance of diabetes mellitus, revealing altered responses to regional anesthesia in diabetic rodents. Pharmacodynamic and pharmacokinetic aspects are investigated in sciatic nerve blocks in diabetic rats, shedding light on heightened responsiveness and prolonged retention of local anesthetics in diabetic neuropathic nerves. Findings of the applied anatomy of the saphenous and obturator nerves for nerve blocks provide valuable insights into the negligible involvement of both nerves in the corresponding blocks. The minimal volume of local anesthetic required for a saphenous nerve block is determined, while we compare the femoral nerve block and adductor canal block in anterior cruciate ligament surgery. The final part of this thesis introduces stem cells to regional anesthesia research. The potential of induced pluripotent stem cells (iPSCs) is discussed as a model for pain signaling, emphasizing their role in pharmaceutical research. We present a functional study with iPSC-derived dorsal root ganglion nociceptors, demonstrating their responsiveness to lidocaine and proposing a model for comprehensive preclinical investigations of analgesics

Effects of early and late diabetic neuropathy on sciatic nerve block duration and neurotoxicity in Zucker diabetic fatty rats

Background The neuropathy of type II diabetes mellitus (DM) is increasing in prevalence worldwide. We aimed to test the hypothesis that in a rodent model of type II DM, neuropathy would lead to increased neurotoxicity and block duration after lidocaine-induced sciatic nerve block when compared with control animals. Methods Experiments were carried out in Zucker diabetic fatty rats aged 10 weeks (early diabetic) or 18 weeks (late diabetic, with or without insulin 3 units per day), and age-matched healthy controls. Left sciatic nerve block was performed using 0.2 ml lidocaine 2%. Nerve conduction velocity (NCV) and F-wave latency were used to quantify nerve function before, and 1 week after nerve block, after which sciatic nerves were used for neurohistopathology. Results Early diabetic animals did not show increased signs of nerve dysfunction after nerve block. In late diabetic animals without insulin vs control animals, NCV was 34.8 (5.0) vs 41.1 (4.1) ms s−1 (P<0.01), and F-wave latency was 7.7 (0.5) vs 7.0 (0.2) ms (P<0.01), respectively. Motor nerve block duration was prolonged in late diabetic animals, but neurotoxicity was not. Late diabetic animals receiving insulin showed intermediate results. Conclusions In a rodent type II DM model, nerves have increased sensitivity for short-acting local anaesthetics without adjuvants in vivo, as evidenced by prolonged block duration. This sensitivity appears to increase with the progression of neuropathy. Our results do not support the hypothesis that neuropathy due to type II DM increases the risk of nerve injury after nerve bloc

Driving pressure during general anesthesia for open abdominal surgery (DESIGNATION) : study protocol of a randomized clinical trial

Background Intraoperative driving pressure (Delta P) is associated with development of postoperative pulmonary complications (PPC). When tidal volume (V-T) is kept constant, Delta P may change according to positive end-expiratory pressure (PEEP)-induced changes in lung aeration. Delta P may decrease if PEEP leads to a recruitment of collapsed lung tissue but will increase if PEEP mainly causes pulmonary overdistension. This study tests the hypothesis that individualized high PEEP, when compared to fixed low PEEP, protects against PPC in patients undergoing open abdominal surgery. Methods The "Driving prESsure durIng GeNeral AnesThesIa for Open abdomiNal surgery trial" (DESIGNATION) is an international, multicenter, two-group, double-blind randomized clinical superiority trial. A total of 1468 patients will be randomly assigned to one of the two intraoperative ventilation strategies. Investigators screen patients aged >= 18 years and with a body mass index <= 40 kg/m(2), scheduled for open abdominal surgery and at risk for PPC. Patients either receive an intraoperative ventilation strategy with individualized high PEEP with recruitment maneuvers (RM) ("individualized high PEEP") or one in which PEEP of 5 cm H2O without RM is used ("low PEEP"). In the "individualized high PEEP" group, PEEP is set at the level at which Delta P is lowest. In both groups of the trial, V-T is kept at 8 mL/kg predicted body weight. The primary endpoint is the occurrence of PPC, recorded as a collapsed composite of adverse pulmonary events. Discussion DESIGNATION will be the first randomized clinical trial that is adequately powered to compare the effects of individualized high PEEP with RM versus fixed low PEEP without RM on the occurrence of PPC after open abdominal surgery. The results of DESIGNATION will support anesthesiologists in their decisions regarding PEEP settings during open abdominal surgery

Human resources for maternal health: multi-purpose or specialists?

A crucial question in the aim to attain MDG5 is whether it can be achieved faster with the scaling up of multi-purpose health workers operating in the community or with the scaling up of professional skilled birth attendants working in health facilities. Most advisers concerned with maternal mortality reduction concur to promote births in facilities with professional attendants as the ultimate strategy. The evidence, however, is scarce on what it takes to progress in this path, and on the 'interim solutions' for situations where the majority of women still deliver at home. These questions are particularly relevant as we have reached the twentieth anniversary of the safe motherhood initiative without much progress made

Midwifery-led antenatal care models: mapping a systematic review to an evidence-based quality framework to identify key components and characteristics of care.

BACKGROUND: Implementing effective antenatal care models is a key global policy goal. However, the mechanisms of action of these multi-faceted models that would allow widespread implementation are seldom examined and poorly understood. In existing care model analyses there is little distinction between what is done, how it is done, and who does it. A new evidence-informed quality maternal and newborn care (QMNC) framework identifies key characteristics of quality care. This offers the opportunity to identify systematically the characteristics of care delivery that may be generalizable across contexts, thereby enhancing implementation. Our objective was to map the characteristics of antenatal care models tested in Randomised Controlled Trials (RCTs) to a new evidence-based framework for quality maternal and newborn care; thus facilitating the identification of characteristics of effective care. METHODS: A systematic review of RCTs of midwifery-led antenatal care models. Mapping and evaluation of these models' characteristics to the QMNC framework using data extraction and scoring forms derived from the five framework components. Paired team members independently extracted data and conducted quality assessment using the QMNC framework and standard RCT criteria. RESULTS: From 13,050 citations initially retrieved we identified 17 RCTs of midwifery-led antenatal care models from Australia (7), the UK (4), China (2), and Sweden, Ireland, Mexico and Canada (1 each). QMNC framework scores ranged from 9 to 25 (possible range 0-32), with most models reporting fewer than half the characteristics associated with quality maternity care. Description of care model characteristics was lacking in many studies, but was better reported for the intervention arms. Organisation of care was the best-described component. Underlying values and philosophy of care were poorly reported. CONCLUSIONS: The QMNC framework facilitates assessment of the characteristics of antenatal care models. It is vital to understand all the characteristics of multi-faceted interventions such as care models; not only what is done but why it is done, by whom, and how this differed from the standard care package. By applying the QMNC framework we have established a foundation for future reports of intervention studies so that the characteristics of individual models can be evaluated, and the impact of any differences appraised