Repurposing CPAP machines as stripped-down ventilators.

The worldwide shortage of medical-grade ventilators is a well-known issue, that has become one of the central topics during the COVID-19 pandemic. Given that these machines are expensive and have long lead times, one approach is to vacate them for patients in critical conditions while patients with mild to moderate symptoms are treated with stripped-down ventilators. We propose a mass-producible solution that can create such ventilators with minimum effort. The central part is a module that can be attached to CPAP machines and repurpose them as low-pressure ventilators. Here, we describe the concept and first measurements which underline the potential of our solution. Our approach may serve as a starting point for open-access ventilator technologies.

[Peripheral truncal blocks-Overview and assessment]. / Periphere Rumpfwandblockaden ­ Übersicht und Bewertung.

By implementation of sonography for regional anesthesia, truncal blocks became more relevant in the daily practice of anesthesia and pain therapy. Due to visualized needle guidance ultrasound supports more safety and helps to avoid complications during needle placement. Additionally, complex punctures are possible that were associated with higher risk using landmarks alone. Next to the blocking of specific nerve structures, interfascial and compartment blocks have also become established, whereby the visualization of individual nerves and plexus structures is not of relevance. The present review article describes published and clinically established puncture techniques with respect to the indications and procedures. The clinical value is reported according to the scientific evidence and the analgesic profile. Moreover, the authors explain potential risks, complications and dosing of local anesthetic agents.

[Selection of the optimal anesthesia regimen for cesarean section]. / Wahl des Anästhesieverfahrens zur Sectio caesarea.

Approximately one third of all children in Germany are delivered by cesarean section. Depending on the individual patient's condition and the situation, the anesthesiologist has to choose between a general or a regional anesthesia regimen. The decisive factor for the selection is the obstetric urgency (decision-delivery time) after ascertainment of the indications. Furthermore, the need for postoperative analgesia varies depending on the chosen anesthesia regimen.

[Stocktaking of local anesthetics 2020]. / Bestandsaufnahme der Lokalanästhetika 2020.

For decades local anesthetics have proven to be safe and effective drugs in the clinical practice, crucially promoting the enormous achievements in regional anesthesia. Meanwhile, it is a well-known fact that local anesthetics are much more than just "simple" sodium channel blockers. They also interact with numerous other ion channels and subcellular structures, enhancing nerve blockade and resulting in systemic "alternative" effects, which can sometimes even be clinically used. By the simultaneous administration of various adjuvants (e.g., opioids, corticosteroids and α2-receptor agonists) attempts are made to prolong the time of action of local anesthetics after a single administration in order to achieve the best possible improvement in postoperative analgesia. In this context, ultralong-acting local anesthetics, such as liposomal bupivacaine, which at least theoretically can provide a sensory nerve block for several days, have been developed and clinically introduced. The coming years will show whether these approaches will develop into genuine alternatives to the personnel and cost-intensive continuous nerve blockades.Local anesthetic-induced systemic toxicity is meanwhile rare but still a potentially life-threatening event, frequently resulting from accidental intravascular injection or extensive systemic resorption. Consequently, slow and fractional application of these agents with intermittent aspiration helps to prevent toxic sequelae. If toxic symptoms occur, however, the intravenous infusion of 20% lipid solutions in addition to basic treatment measures can enhance the success of treatment.

Epidural needle insertion : A large registry analysis.

BACKGROUND: Dural puncture, paraesthesia and vascular puncture are the most common complications of epidural catheter insertion. Their association with variation in midline needle insertion depth is unknown. OBJECTIVE: This study evaluated the risk of dural and vascular punctures and the unwanted events paraesthesia and multiple skin punctures related to midline needle insertion depth. MATERIAL AND METHODS: A total of 14,503 epidural catheter insertions including lumbar (L1-L5; n = 5367), low thoracic (T7-T12, n = 8234) and upper thoracic (T1-T6, n = 902) insertions, were extracted from the German Network for Regional Anaesthesia registry between 2007 and 2015. The primary outcomes were compared with logistic regression and adjusted (adj) for confounders to determine the risk of complications/events. Results are presented as odds ratios (OR, [95% confidence interval]). MAIN RESULTS: Midline insertion depth depended on body mass index, sex, and spinal level. After adjusting for confounders increased puncture depth (cm) remained an independent risk factor for vascular puncture (adjOR 1.27 [1.09-1.47], p = 0.002) and multiple skin punctures (adjOR 1.25 [1.21-1.29], p < 0.001). In contrast, dural punctures occurred at significantly shallower depths (adjOR 0.73 [0.60-0.89], p = 0.002). Paraesthesia was unrelated to insertion depth. Body mass index and sex had no influence on paraesthesia, dural and vascular punctures. Thoracic epidural insertion was associated with a lower risk of vascular puncture than at lumbar sites (adjOR 0.39 [0.18-0.84], p = 0.02). CONCLUSION: Variation in midline insertion depth is an independent risk factor for epidural complications; however, variability precludes use of depth as a reliable guide to insertion in individual patients.

[Airway management for lung separation in thoracic surgery : An update]. / Atemwegsmanagement zur Seitentrennung der Lunge bei thorakalen Eingriffen : Ein Update.

One of the main tasks in every anesthetist's routine clinical practice is securing the airway. This also includes techniques for lung isolation and one-lung ventilation in thoracic surgery and in intensive care medicine. The anesthesiologist has various methods available to achieve one-lung ventilation. This article presents the most commonly used methods for lung isolation. These include the double lumen tube, the bronchus blockers by Arndt and Cohen, the EZ blocker, the Uniblocker, the Univent tube and the VivaSight-DL™. The effects of the one-lung ventilation are not described in detail and for this the reader should refer to the appropriate literature. This article is intended to provide an overview of the various possibilities for lung separation, especially for physicians in continued medical education and also for physicians who rarely use these procedures.

One year after proximal or distal periprosthetic fracture of the femur -two conditions with divergent outcomes?

INTRODUCTION: Arthroplasty of the hip and knee is 1 of the 20 most frequent operations in Germany. Periprosthetic fracture is one of the most feared complications following primary or revision arthroplasty. Present publication aims to analyse differences between patients with periprosthetic fracture around total knee arthroplasty (PFTKA) and patients with periprosthetic fracture around total hip arthroplasty (PFTHA) concerning demographics, clinical course, complications and return to pre-fracture mobility. METHODS: Prospective single-centre observation study of periprosthetic femoral fractures with stable implants. Present subgroup analysis includes patients with PFTKA and PFTHA. All patients were treated with polyaxial angular stable plates using two standardized techniques: a minimally invasive percutaneous distal insertion technique and a mini-open technique. Data collection included implant- and operation-related information as well as demographics, clinical course, complications and return to pre-fracture mobility. Data were collected during a 12-month follow-up. RESULTS: We were able to analyse the data of 73 patients. The PFTKA group had 37 patients with a mean age of 76 ±â€¯10 years; 88% were female. After 1 year, 3 patients in this cohort had died; 68% of survivors had reached their pre-fracture mobility; 22% had undergone operative revisions for various reasons. The PFTHA cohort included 36 patients with a mean age of 80 ±â€¯13 years, 72% were female. After 1 year, 9 patients had died in this cohort, 42% of survivors had reached their pre-fracture mobility. Non-operative complications occurred for 16% in the PFTKA group and 64% in the PFTHA group (p < 0.001). 11% had undergone operative revisions for various reasons, among them, two cases of nonunion but no primary infection. CONCLUSION: On average, compared to the PFTHA patients, PFTKA patients were younger, underwent significantly lower rates of non-operative complications, had a tendency towards lower mortality, and returned to pre-fracture mobility at higher rates, although they tended to have more revisions when compared to treatment for PFTHA. Overall, when periprosthetic fractures of the femur were treated using polyaxial locking plate osteosynthesis, patients showed very low rates of nonunion and no primary infection.

Intraneural injection of a test dose of local anesthetic in peripheral nerves - does it induce histological changes in nerve tissue?

BACKGROUND & OBJECTIVES: Most anesthesiologists use the injection of a test dose of local anesthetic in order to evaluate the final needle tip position. Thus, the intraneural injection of a full dose can be avoided. The aim of this study was to analyze whether an intraneural injection of a test dose of bupivacaine could trigger histological changes. METHODS: Intraneural injections under direct vision were performed in 40 brachial plexus nerves in seven anesthetized pigs. Tibial nerves served as positive and negative controls. Two milliliter of bupivacaine 0.5% was injected in three nerves on the left brachial plexus. For control of local anesthetic's toxicity Ringer's solution was applied intraneurally on the right side. After maintaining 48 h of general anesthesia, the nerves were resected. The specimens were processed for histological examination and assessed for inflammation (hematoxylin and eosin stain, CD68-immunohistochemistry) and myelin damage (Kluver-Barrera stain). The degree of nerve injury was rated on a scale from 0 (no injury) to 4 (severe injury). RESULTS: Statistical analysis showed no significant differences between the bupivacaine group [median (interquartile range) 1 (1-1.5)] and the Ringer's solution group [1 (0.5-2) P = 0.772]. Mild myelin alteration was found in 12.5% of all specimens following intraneural injection, irrespective of the applied substance. CONCLUSIONS: "In our experimental study, intraneural injection of 2 ml of bupivacaine or Ringer's solution showed comparable mild inflammation. Nevertheless, inflammation can only be prevented by strictly avoiding nerve perforation followed by intraneural injection, as mechanical nerve perforation is a key factor for evolving inflammation.

Nutritional intervention in cognitively impaired geriatric trauma patients: a feasibility study.

BACKGROUND: Most studies focusing on improving the nutritional status of geriatric trauma patients exclude patients with cognitive impairment. These patients are especially at risk of malnutrition at admission and of worsening during the perioperative fasting period. This study was planned as a feasibility study to identify the difficulties involved in including this high-risk collective of cognitively impaired geriatric trauma patients. PATIENTS AND METHODS: This prospective intervention study included cognitively impaired geriatric patients (Mini-Mental State Examination <25, age >65 years) with hip-related fractures. We assessed Mini Nutritional Assessment (MNA), Nutritional Risk Screening (NRS 2002), body mass index, calf circumference, American Society of Anesthesiologists' classification, and Braden Scale. All patients received parenteral nutritional supplementation of 800 kcal/d for the 96-hour perioperative period. Serum albumin and pseudocholinesterase were monitored. Information related to the study design and any complications in the clinical course were documented. RESULTS: A total of 96 patients were screened, among whom eleven women (median age: 87 years; age range: 74-91 years) and nine men (median age: 82 years; age range: 73-89 years) were included. The Mini-Mental State Examination score was 9.5 (0-24). All patients were manifestly undernourished or at risk according to MNA and NRS 2002. The body mass index was 23 kg/m2 (13-30 kg/m2), the calf circumference was 29.5 cm (18-34 cm), and the mean American Society of Anesthesiologists' classification status was 3 (2-4). Braden Scale showed 18 patients at high risk of developing pressure ulcers. In all, 12 patients had nonsurgical complications with 10% mortality. Albumin as well as pseudocholinesterase dropped significantly from admission to discharge. The study design proved to be feasible. CONCLUSION: The testing of MNA and NRS 2002 was feasible. Cognitively impaired trauma patients proved to be especially at risk of malnutrition. Since 96 hours of parenteral nutrition as a crisis intervention was insufficient, additional supplementation could be considered. Laboratory and functional outcome parameters for measuring successive supplementation certainly need further evaluations involving randomized controlled trials.

Phrenic palsy and analgesic quality of continuous supraclavicular vs. interscalene plexus blocks after shoulder surgery.

BACKGROUND: Hemidiaphragmatic palsy is a common consequence of the interscalene brachial plexus block. It occurs less commonly with the supraclavicular approach. Register data suggest that the analgesic quality of a supraclavicular blockade is sufficient for arthroscopic shoulder surgery, although data on the post-operative analgesic effect are lacking. METHODS: After approval by the ethics committee, patients having arthroscopic shoulder surgery under general anaesthesia were randomized to receive a continuous interscalene or supraclavicular blockade. Phrenic nerve function was evaluated through ultrasound examination of the diaphragm in combination with spirometry. Pain scores at rest and activity etc. were determined before catheter insertion, during observation in the post- anaesthesia care unit (PACU) and on post-operative day 1 (POD1). The initial application of 10 ml of ropivacaine 0.2% was followed by continuous application of 4 ml of ropivacaine 0.2%, plus a patient controlled analgesia (PCA) bolus of 4 ml/h. RESULTS: One hundred and twenty patients were randomized, of which 114 data sets were analysed. Complete hemidiaphragmatic paresis occurred in 43% of the interscalene group vs. 24% in the supraclavicular group during PACU stay. Rates of dyspnoea and hoarseness were similar. Horner's syndrome occurred in 21% of the interscalene but only 3% of the supraclavicular group on POD1. Pain scores were comparable for pain at rest and during stress at each time point. CONCLUSIONS: This trial showed a significantly greater incidence of phrenic nerve palsy of the interscalene group in PACU, but not on POD1. Post-operative analgesic quality was similar in both groups. Continuous supraclavicular blockade is a suitable alternative to the continuous interscalene technique.

[Glucocorticoids as an adjunct in peripheral regional anesthesia. Move to the "Holy Grail of perineural analgesia"?!]. / Glucocorticoide als Adjuvanz in der peripheren Regionalanästhesie : Unterwegs zum "Heiligen Gral der perineuralen Analgesie"?!

BACKGROUND: The role of dexamethasone as an adjunct in peripheral nerve blockades is still unclear. OBJECTIVES: This article reviews the actual knowledge and scientific evidence for dexamethasone as an adjunct in peripheral regional anesthesia. Moreover, it discusses the benefits of the systemic versus the perineural mode of application. RESULTS: Dexamethasone prolongs sensible as well as motor blockades in peripheral nerve blocks when applied intravenously or perineurally. Regarding potentially local neurotoxicity, published patient data are not sufficient for final conclusions. CONCLUSIONS: After reviewing the actual literature, the authors prefer a systemic application mode (intravenously) over a perineural route of administration of dexamethasone as an adjunct for peripheral nerve blocks. This is due to the better understanding of potential side effects of the drug when applied intravenously. Dexamethasone might be a useful drug adjunct to prolong peripheral single shot nerve blocks.

Risk evaluation for needle-nerve contact related to electrical nerve stimulation in a porcine model.

BACKGROUND: For performing peripheral nerve blocks, the risk for needle-nerve contact (NNC) as an adverse event for low and high current thresholds has not yet been clearly defined when nerve stimulator guided techniques were applied. This experimental study aimed to investigate the risk of NNCs when applying stimulation currents between 0.1 and 2 mA (in increments of 0.1 mA). METHODS: Brachial plexus nerves were exposed surgically in five anesthetized pigs. An insulated needle connected to a nerve stimulator was placed at 10 mm distance to the targeted nerves. Current intensity was adjusted according to randomization (0.1-2.0 mA, increments of 0.1 mA). The needle tip was advanced toward the nerve until a motor response was elicited. The frequencies of NNCs for each of the adjusted current intensities were noted. Risks of NNCs were calculated according to the analysis of 95% confidence intervals (95% CI). RESULTS: We executed 2000 needle placements with stimulation currents ranging from 0.1 to 2.0 mA. The risks for NNC at low current intensities were 0.85 (95% CI, 0.77-0.91) for 0.3 mA and 0.5 (95% CI, 0.4-0.6) for 0.5 mA, respectively. For high current intensities, risks of 0.13 (95% CI, 0.07-0.21) for 0.9 mA and 0.01 (95% CI, 0-0.05) for 1.1 mA were calculated. CONCLUSIONS: In this experimental animal study, a relevant reduction in the risk of NNCs could be observed when high current intensities (0.9-1.1 mA) were applied compared to low current intensities (0.3-0.5 mA).

A porcine polytrauma model with two different degrees of hemorrhagic shock: outcome related to trauma within the first 48 h.

BACKGROUND: An animal polytrauma model was developed, including trunk and extremity injuries combined with hemorrhagic shock and a prolonged post-traumatic phase. This could be useful for the assessment of different therapeutic approaches during intensive care therapy. METHODS: A standardized polytrauma including lung contusion, liver laceration and lower leg fracture was applied in 25 pigs. They underwent controlled haemorrhage either with a blood volume loss of 45 % and a median arterial pressure (MAP) <30 mmHg/90 min (group L, n = 15) or a 50 % blood loss of and an MAP <25 mmHg/120 min (group H, n = 10). Five non-traumatized pigs served as a control (group C). Subsequently, intensive care treatment was given for an observational period of 48 h. RESULTS: Both trauma groups showed signs of shock and organ injury (heart rate, MAP and lactate). The frequency of cardiopulmonary resuscitation (CPR) and lung injury was directly related to the severity of the haemorrhagic shock (CPR-group L: 4 of 15 pigs, group H: 4 of 10 pigs; Respiratory failure-group L: 3 of 13, group H: 3 of 9. There was no difference in mortality between trauma groups. CONCLUSION: The present data suggest that our model reflects the mortality and organ failure of polytrauma in humans during shock and the intensive care period. This suggests that the experimental protocol could be useful for the assessment of therapeutic approaches during the post-traumatic period.

Needle-nerve proximity during peripheral nerve blocks - Where is the right target and how can we get there? / Proximidad aguja-nervio durante los bloqueos nerviosos: ¿Cuál es el punto correcto y cómo podemos llegar ahí?

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[Seeing more : Technical innovations in regional anesthesia]. / Mehr sehen : Technische Innovationen in der Regionalanästhesie.

Visualization and verification are key factors since the implementation of ultrasound-guided regional anesthesia. This article reviews and discusses newer technical innovations in regional anesthesia with regard to optimization of needle guidance, improvements in needle visibility, technical improvements in ultrasound techniques and innovative technologies in regional anesthesia. Clinically available applications are presented as well as experimental tools and techniques with a potential for clinical implementation in the future. Mechanical needle guides are used to improve alignment of needle axis and ultrasound beam axis. Compound imaging technology improves needle visibility in steep needle insertion angles and is already implemented in daily clinical practice. Sonoelastography improves tissue discrimination and detection of small amounts of fluids. Benefits of 3D and 4D ultrasound in regional anesthesia are discussed as well as experimental tools for tissue discrimination, such as optical reflection spectrophotometry.

Nerve localization for peripheral regional anesthesia. Recommendations of the German Society of Anaesthesiology and Intensive Care Medicine.

The German Society of Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin, DGAI) established an expert panel to develop preliminary recommendations for nerve localization in peripheral regional anesthesia. Based on expert knowledge and the relatively limited data, the recommendations state how ultrasound and/or electrical nerve stimulation should be used in daily practice, and where and when local anesthetics should be injected. Moreover, it was defined under which conditions a peripheral nerve block under general anesthesia or deep sedation is applicable.Regarding the use of ultrasound the expert opinion was that out-of-plane and in-plane-techniques can be considered equal with respect to patient safety. Nevertheless, the direct or indirect visualization of the needle tip has to be assured. The injection of local anesthetics has to be visualized. Injections into nerves or those requiring an injection pressure should be avoided. The sole use of electrical nerve stimulation or ultrasound for nerve localization is still a suitable option as well as their combined use. To avoid accidental intraneural needle placement, an electrical current threshold ≥ 0.5 mA should be used. Moreover, it was stated that peripheral nerve blocks or continuous nerve block techniques under sedation or general anesthesia are applicable in adult patients who are unable to tolerate the block being performed in an awake state or have difficulty cooperating.This article is published in English.

Supplemental single shot femoral nerve block for total hip arthroplasty: impact on early postoperative care, pain management and lung function.

BACKGROUND AND AIM: Peripheral regional anesthesia is beneficial in the management of postoperative pain in hip surgery, and can also reduce post-operative care unit (PACU) stay. Its opioid-sparing actions may also be beneficial for respiratory mechanics and pulmonary function. The aim of our pilot study was to evaluate the effect of a supplemental single shot femoral block for elective total hip arthroplasty on early respiratory function and postoperative management within the first 24 postoperative hours. METHODS: We prospectively studied 80 patients undergoing total hip arthroplasty. Written informed consent was obtained after ethics committee approval. Forty patients were randomLy assigned to receive single shot femoral nerve block (FNB) using 15mL bupivacaine 0.25% and 20 mg clonidine while the remainder received standard treatment without nerve block (STN). Premedication and general anesthesia were standardized. Pulse oximetry saturation and spirometric lung function were measured preoperatively (baseline) and at 0.5 h, 2 h, 6 h and 24 h, after extubation breathing room air. PACU surveillance and postoperative pain therapy was standardized. RESULTS: Oxygen saturation and spirometry results were significantly better within the FNB group during the first six postoperative hours. Although VAS scores during the PACU stay did not significantly differ between the study groups, PACU discharge criteria were met earlier in the FNB group (116±40 min [mean±SD] vs. 152±47 min in the STN group). The FNB group exhibited significantly lower VAS scores at 6 and 24 hours. CONCLUSION: Supplemental single shot femoral nerve block for total hip arthroplasty resulted in earlier PACU discharge capability, improved lung function during the first six hours and better pain control within the first 24 postoperative hours.

Needle visibility in different tissue models for ultrasound-guided regional anaesthesia.

BACKGROUND: Models for ultrasound-guided regional anaesthesia (USGRA) are important for research and training. However, the limited data available show great differences in quality of needle and tissue visualisation with regard to the applied model. This study aims to compare common USGRA models and human tissue with regard to their influence on needle visibility. METHODS: We conducted this study using four models (embalmed human cadaver, turkey breast, pork, and synthetic gel models) and a volunteer (human control) as well as two different needles [Stimuplex A (StA), conventional needle; Stimuplex D Plus (StD+), needle with improved echogenicity]. We obtained ultrasound videos of needle advancement and withdrawal using the in-plane approach at a 45° angle in all four models and the volunteer. Fifteen test persons were prospectively enrolled. Ultrasound videos were presented in a randomised, blinded manner. The test persons were asked to rate the visibility of the needle shaft (VS) and tip (VT) on a four-point scale (0-3). RESULTS: VS and VT were comparable between the human control and cadaver model for both needle types. The pork, turkey, and synthetic gel models had significantly higher visibility scores than the human control for both needle types. VS of StD+ was significantly higher than that of StA in the pork and turkey models, but not in the synthetic model, cadaver model, or human control. CONCLUSION: In this pilot study, needle visibility in embalmed cadaver is comparable with that in human control. Needle visibility was significantly higher in other tissue models (turkey breast, pork, synthetic gel models) than in the human control, which may limit their value in training environments.