[Focused Transthoracic Echocardiography in the Perioperative Setting]. / Die fokussierte transthorakale Echokardiografie in der perioperativen Versorgung.

With focused transthoracic echocardiography (TTE) we rapidly and non-invasively receive up-to-date information on a patient's hemodynamic status. These can subsequently influence our therapy and thus our risk management. Postoperatively, TTE has proved its worth as an examination method in the recovery room and in the intensive care unit to promptly diagnose life-threatening causes of circulatory depression. Acute pathology such as a pericardial tamponade or fulminant pulmonary artery embolism can be detected quickly and thus possibly time-consuming transport to a CT can be avoided. Also, preoperatively, the use of TTE may be useful for assessing volume status, pumping function, or hemodynamically relevant heart defects. Especially in surgical interventions with a high perioperative risk of complications, these findings can be incorporated into a goal-directed therapy. Corresponding algorithms for enhanced hemodynamic monitoring and volume management already exist in many areas, but they are often not consistently implemented in the processes of their own clinic. In this article, we demonstrate the utility and relevance of TTE hemodynamic evaluation at every stage of patient care. We also present a possible algorithm for the care of critically ill patients, based on the main transthoracic and hemodynamic measurements. It is intended to provide assistance in the meaningful use of TTE in everyday clinical practice and especially for those on on-call duty.

Feasibility and Impact of Focused Intraoperative Transthoracic Echocardiography on Management in Thoracic Surgery Patients: An Observational Study.

OBJECTIVES: Intraoperative focused transthoracic echocardiography (TTE) is feasible and has an effect on the management of hemodynamically unstable surgical patients. Furthermore, in noncardiac thoracic surgery, TTE might provide additional information for hemodynamic treatment. Transthoracic accessibility during thoracic surgical interventions is assumed to be difficult. For patients positioned on their right side, a modified subcostal transthoracic view might be helpful. DESIGN: A prospective observational study. SETTING: Single-center university hospital. PARTICIPANTS: The study comprised 105 consecutive patients undergoing noncardiac thoracic surgery. INTERVENTIONS: Focused TTE was performed during anesthetic induction after intubation for mechanical ventilation. Intraoperative focused TTE, after positioning and draping for surgery, was attempted again for all 105 patients. Changes in patient management due to the results of the TTE were documented and analyzed. MEASUREMENTS AND MAIN RESULTS: Presurgical TTE with mechanical ventilation was applied successfully in 98.1% of 105 patients. Intraoperative imaging was successful in 90 patients (85.7%). Results of intraoperative TTE led to the modification of perioperative management in 39 patients (37.1%), 20 (22.0%) of these during surgery. CONCLUSIONS: TTE in noncardiac thoracic surgery is feasible using a modified subcostal view and has an effect on hemodynamic management in a considerable number of patients.

Risk perception of blood transfusions - a comparison of patients and allied healthcare professionals.

BACKGROUND: Due to an increasing demand in health care services plans to substitute selective physician-conducted medical activities have become attractive. Because administration of a blood transfusion is a highly standardized procedure, it might be evaluated if obtaining a patient's consent for a blood transfusion can be delegated to allied healthcare professionals. Physicians and patients perceive risks of transfusions differently. However, it is unknown how allied healthcare professionals perceive risks of transfusion-associated adverse events. METHODS: Patients (n = 506) and allied healthcare professionals (n = 185) of an academic teaching hospital were asked to quantify their concerns about transfusions including five predefined transfusion-associated risks and their incidences. RESULTS: Blood transfusions were considered to be generally harmful by 10.9% of patients and 14.6% of caregivers (P = 0.180). Among all surveyed patients, 36.8% were worried about infection-transmissions (caregivers: 27.6%; P = 0.024). Compared to 5.4% of caregivers, 13.6% of patients believed infection-transmission was a frequent complication (P = 0.003). Caregivers ranked the risks of receiving an AB0-mismatch transfusion (caregivers: 29.7% vs. PATIENTS: 19.2%, P = 0.003) or a transfusion-associated allergic reaction (caregivers: 17.3% vs. PATIENTS: 11.1%, P = 0.030) significantly higher than patients and were aware of the high incidence of transfusion-associated fever (caregivers: 17.8% vs. PATIENTS: 8.3%, P < 0.001). CONCLUSION: A significant part of interviewees perceived transfusions as a general health hazard. Patients perceived infection-transmissions as the most frequent and greatest transfusion-associated threat while caregivers focused on fatal AB0-mismatch transfusions and allergic reactions. Understanding the patients' main concerns about blood transfusions and considering that these concerns might differ from the view of healthcare professionals might improve the process of shared decision making.

Recovery and prediction of postoperative muscle power - is it still a problem?

BACKGROUND: In the postoperative period, immediate recovery of muscular power is essential for patient safety, but this can be affected by anaesthetic drugs, opioids and neuromuscular blocking agents (NMBA). In this cohort study, we evaluated anaesthetic and patient-related factors contributing to reduced postoperative muscle power and pulse oximetric saturation. METHODS: We prospectively observed 615 patients scheduled for minor surgery. Premedication, general anaesthesia and respiratory settings were standardized according to standard operating procedures (SOP). If NMBAs were administered, neuromuscular monitoring was applied to establish a Train of four (TOF)-Ratio of >0.9 before extubation. After achieving a modified fast track score > 10 at 4 time points up to 2 h postoperatively, we measured pulse oximetric saturation and also static and dynamic muscle power, using a high precision digital force gauge. Loss of muscle power in relation to the individual preoperative baseline value was analysed in relation to patient and anaesthesia-related factors using the T-test, simple and multiple stepwise regression analysis. RESULTS: Despite having achieved a TOF ratio of >0.9 a decrease in postoperative muscle power was detectable in most patients and correlated with reduced postoperative pulse oximetric saturation. Independent contributing factors were use of neuromuscular blocking agents (p < 0.001), female gender (p = 0.001), TIVA (p = 0.018) and duration of anaesthesia >120 min (p = 0.019). CONCLUSION: Significant loss of muscle power and reduced pulse oximetric saturation are often present despite a TOF-Ratio > 0.9. Gender differences are also significant. A modified fast track score > 10 failed to predict recovery of muscle power in most patients. TRIAL REGISTRATION: German Clinical Trial Register DRKS-ID DRKS00006032 ; Registered: 2014/04/03.

Impact of Focused Intraoperative Transthoracic Echocardiography by Anesthesiologists on Management in Hemodynamically Unstable High-Risk Noncardiac Surgery Patients.

OBJECTIVES: Focused transthoracic echocardiography (TTE) is used perioperatively for surgical patients. Intraoperative application of TTE is feasible, but its benefits remain unclear. The intention of this study was to investigate the effect of intraoperative TTE on the management of high-risk noncardiac surgery patients. DESIGN: A prospective interventional study. SETTING: Single-center university hospital. PARTICIPANTS: Fifty consecutive hemodynamically unstable high-risk patients anesthetized for noncardiac surgery. INTERVENTIONS: Focused TTE was performed on hemodynamically unstable anesthetized patients whenever circulatory instability (defined as hypotension or low cardiac output) occurred intraoperatively. A cardiac output monitoring system using pulse contour analysis was established before induction of anesthesia. The intended therapy for stabilizing the patient was documented; however, the management actually administered was guided by the results of the TTE. Differences between the 2 lines of management were documented and analyzed. MEASUREMENTS AND MAIN RESULTS: Intraoperative TTE was applied successfully in all 50 unstable patients. In 33 patients (66%, 95% confidence interval, 52.11-77.61) TTE led to a change of management. Altogether, 82 episodes of hemodynamic instability were recorded, including 38 episodes (46.34%, 95% confidence interval, 35.95-57.06) in which TTE led to a change of treatment. The most common pathologic finding was hypovolemia (66%); in contrast, in 22%, right-heart overload or right-heart failure (4%) was detected. CONCLUSIONS: Focused TTE by anesthesiologists can provide new information that may alter the hemodynamic management of unstable high-risk noncardiac surgery patients in the operating room.

Continuous adductor canal block versus continuous femoral nerve block after total knee arthroplasty for mobilisation capability and pain treatment: a randomised and blinded clinical trial.

INTRODUCTION: Continuous femoral nerve blocks for total knee arthroplasty can cause motor weakness of the quadriceps muscle and thus prevent early mobilisation. Perioperative falls may result as an iatrogenic complication. In this randomised and blinded trial, we tested the hypothesis that a continuous adductor canal block is superior to continuous femoral nerve block regarding mobilisation ('timed up-and-go' test and other tests) after total knee arthroplasty under general anaesthesia. METHODS: In our study, we included patients scheduled for unilateral knee arthroplasty under general anaesthesia into a blinded and randomised trial. Patients were allocated to a continuous adductor canal block (CACB) or a continuous femoral nerve block (CFNB) for three postoperative days (POD 1-3); with a bolus of 15 ml ropivacaine 0.375%, followed by continuous infusion of ropivacaine 0.2% and patient-controlled bolus administration. Both groups received an additional continuous sciatic nerve block as well as a multimodal systemic analgesic treatment. The primary outcome parameter was mobilisation capability, assessed by 'timed up-and-go' (TUG) test. Analgesic quality, need for opioid rescue and local anaesthetic consumption were also assessed. RESULTS: Forty-two patients were included and analysed (21 patients per group). No significant difference was noted in respect to mobilisation at POD 3 (TUG [s]: CACB 45, CFNB 51). It is worth saying that pain scores (numeric rating scale, NRS) were similar in both groups at POD 3 {rest [median (interquartile range)]: CACB 0 (0-3), CFNB 1 (0-3); stress: CACB 4 (2-5), CFNB 3 (2-4)}. CONCLUSIONS: Concerning the mobilisation capability, we did not actually observe a superior effect of CACB compared with CFNB technique in our patients following total knee arthroplasty. Moreover, no difference was observed concerning analgesia quality.

Occurrence of rapid eye movement sleep deprivation after surgery under regional anesthesia.

BACKGROUND: Sleep disturbances after general surgery have been described. In this study, we assessed rapid eye movement (REM) sleep in patients undergoing knee replacement surgery using a regional anesthetic technique. METHODS: Ambulatory polysomnography (PSG) was performed on 3 nights: the night before surgery (PSG1), the first night after surgery (PSG2), and the fifth postoperative night (PSG3). Postoperative analgesia was maintained with peripheral nerve catheters for the first 3 days and with oral opioids thereafter. In addition, nonsteroidal antiinflammatory drugs were administered. Postoperative pain was monitored using a visual analog scale. RESULTS: PSG was performed in 12 patients, 6 men and 6 women, with a mean age of 61 (±12) years. REM sleep was reduced from PSG1 (median 16.4%) to PSG2 (median 6.3%; P = 0.02). The Hodges-Lehmann estimate for the median reduction is -7.8% (95% confidence interval -14.8% to -0.7%). During PSG3, significantly more REM sleep was detected (median 15.4%) compared with PSG2 (P = 0.01). The Hodges-Lehmann estimate for this median increase is 10.0% (95% confidence interval 1.7%-25.3%). CONCLUSION: Postoperative reduction of REM sleep also occurs after surgery and regional anesthesia.

Forced needle advancement during needle-nerve contact in a porcine model: histological outcome.

BACKGROUND: In this study, we determined whether needle advancement during needle-nerve contact (forced needle-nerve contact) is associated with a higher risk of nerve injury compared with needle-nerve contact without needle advancement (nonforced needle-nerve contact). METHODS: In 8 anesthetized pigs, the brachial plexus nerves underwent forced (0.15 Newton) or nonforced (0.0 Newton) needle-nerve contact without nerve penetration. The grade of nerve injury was histologically assessed using an objective score ranging from 0 (no injury) to 4 (severe injury). RESULTS: Sixty-nine nerves, including controls, were examined. Histology revealed a significant difference between forced and nonforced needle-nerve contact (median [interquartile range] 3 [2-4] vs 2 [1-2]; P = 0.004). Myelin damage and intraneural hematoma occurred only after forced needle-nerve contact. CONCLUSIONS: The severity of structural nerve injury after needle-nerve contact was directly related to force exposure via needle advancement.

Short term non-invasive ventilation post-surgery improves arterial blood-gases in obese subjects compared to supplemental oxygen delivery - a randomized controlled trial.

BACKGROUND: In the immediate postoperative period, obese patients are more likely to exhibit hypoxaemia due to atelectasis and impaired respiratory mechanics, changes which can be attenuated by non-invasive ventilation (NIV). The aim of the study was to evaluate the duration of any effects of early initiation of short term pressure support NIV vs. traditional oxygen delivery via venturi mask in obese patients during their stay in the PACU. METHODS: After ethics committee approval and informed consent, we prospectively studied 60 obese patients (BMI 30-45) undergoing minor peripheral surgery. Half were randomly assigned to receive short term NIV during their PACU stay, while the others received routine treatment (supplemental oxygen via venturi mask). Premedication, general anaesthesia and respiratory settings were standardized. We measured arterial oxygen saturation by pulse oximetry and blood gas analysis on air breathing. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 1 h, 2 h, 6 h and 24 h after extubation, with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P < 0.05. RESULTS: There were no differences at the first assessment. During the PACU stay, pulmonary function in the NIV group was significantly better than in the controls (p < 0.0001). Blood gases and the alveolar to arterial oxygen partial pressure difference were also better (p < 0.03), but with the addition that overall improvements are of questionable clinical relevance. These effects persisted for at least 24 hours after surgery (p < 0.05). CONCLUSION: Early initiation of short term NIV during in the PACU promotes more rapid recovery of postoperative lung function and oxygenation in the obese. The effect lasted 24 hours after discontinuation of NIV. Patient selection is necessary in order to establish clinically relevant improvements. TRIAL REGISTRATION#: DRKS00000751; http://www.germanctr.de.

The influence of perioperative oxygen concentration on postoperative lung function in moderately obese adults.

BACKGROUND AND OBJECTIVE: Obesity aggravates the negative effects of general anaesthesia and surgery on the respiratory system, resulting in decreased functional residual capacity and expiratory reserve volume, and increased atelectasis and ventilation/perfusion (Va/Q) mismatch. High-inspired oxygen concentrations also promote atelectasis. This study compares the effects of perioperative inspired low-oxygen and high-oxygen concentrations on postoperative lung function and pulse oximetry values in moderately obese patients (BMI 25-35). METHODS: We prospectively studied 142 overweight patients, BMI 25-35, undergoing minor peripheral surgery; they were randomly allocated to receive either low-inspired or high-inspired oxygen concentrations during general anaesthesia. Premedication, general anaesthesia and respiratory patterns were standardized. Arterial oxygen saturation (pulse oximetry) was measured on air breathing. Inspiratory and expiratory lung functions were measured preoperatively (baseline) and at 10 min, 0.5, 2 and 24 h after extubation with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance and t-test analysis. RESULTS: The low-inspired oxygen group had significantly better arterial saturation during the first 24 h (P < 0.01). Mid-expiratory flow 25 values indicating small airway collapse were significantly better in the low-oxygen group at all measurements (P < 0.05). CONCLUSION: We conclude that postoperative lung function and arterial saturation is better preserved by a low-oxygen strategy, although it is not clear whether this has clinical relevance for the prevention of postoperative pulmonary complications.

A simplified risk score to predict difficult intubation: development and prospective evaluation in 3763 patients.

BACKGROUND AND OBJECTIVE: Despite the presence of numerous preoperative tests to predict a difficult airway, there is no reliable bedside method. The aim of this study was to create and verify a simplified risk model with an acceptable discriminating power. METHODS: A total of 3763 patients from two university hospitals were screened for potential risk factors for difficult intubation, defined as needing additional technical or human resources, more than three attempts or duration more than 10 min. A random sample (n = 2509) was subjected to multivariate stepwise logistic regression analysis, and the most powerful independent risk factors were used to build a simplified model that was applied to a validation dataset (n = 1254). RESULTS: The following factors (odds ratio) were associated with a difficult intubation: presence of upper front teeth (3.61), history of difficult intubation (2.88), any Mallampati status different from '1' (2.55) or equal to '4' (1.91) and mouth opening less than 4 cm (1.80). The discriminating power of the score was 0.72 (95% confidence interval 0.63-0.81). The likelihood for a difficult intubation increases continuously from 0 (when no risk factor is present) to 2, 4, 8 and 17%, when one, two, three and more than three factors are present. CONCLUSION: The new simplified multivariate risk score for difficult intubation may prove to be useful in clinical practice for predicting a difficult airway. Presence of upper front teeth, a history of difficult intubation, any Mallampati status different from '1' and equal to '4' and mouth opening less than 4 cm are independent risk factors for difficult endotracheal intubation. With each of these risk factors, the likelihood increases from 0 (when no risk factor is present) to 17% (when four or five factors are present).

[Spinal anaesthesia in day case surgery--Old technique--new trends]. / Spinalanästhesie--Ambulante Spinalanästhesie--Neue Trends einer alten Technik.

Day case surgery is becoming more and more important. In order to perform these services cost-efficiently it is of primary importance to ensure that procedures can be scheduled with the largest possible patient satisfaction. Up to now spinal anaesthesia was of little importance in day case surgery due to prolonged nerve block and negative side effects especially when using long acting local anaesthetics. Since prilocaine and 2-chloroprocaine, two short acting local anaesthetics with a known low incidence of side effects, were recently introduced into clinical practice a reevaluation of spinal anaesthesia in a day case setting according to EMB guidelines still has to be done.

Indicated trauma emergency department utilization - A comparison between patients' self-assessment and professional evaluation.

INTRODUCTION: Patient visits to emergency departments (EDs) increase in many countries. As a result, these facilities are often congested and the socioeconomic burden of growing workload is a well-known problem. In this study, patients' reasons attending an ED with non-emergent needs were analyzed. METHODS: From October 2015 to March 2016 patients (n = 499), attending the ED of an academic teaching hospital without referral from a General Practitioner (GP) were surveyed regarding circumstances of their visit, a self-assessment of illness-severity, and reasons for choosing the ED instead of a GP. Results were compared to responses of ED staff (n = 40). RESULTS: Most patients assessed their case as urgent (patients: 65% vs. ED staff: 28%, p < 0.001) and felt that their medical problem could not to be treated by a GP (74%). However, most patients ranked their injuries as mild (45.7%) or moderate (41.7%). Reasons to prefer an ED instead of a GP were not responded in 80.1% of cases. CONCLUSION: In contrast to the self-evaluation of patients, ED staff believed that a significant portion of medical problems could be treated by a GP. Understanding patient-centred reasons and the discrepancy between self-perceived emergencies and minor medical problems might help to reduce inappropriate ED-admissions.

Implementation and effects of pulse-contour- automated SVV/CI guided goal directed fluid therapy algorithm for the routine management of pancreatic surgery patients.

BACKGROUND: Goal directed fluid management in major abdominal surgery has shown to reduce perioperative complications. The approach aims to optimize the intravascular fluid volume by use of minimally invasive devices which calculate flow-directed variables such as stroke volume (SV) and stroke volume variation (SVV). OBJECTIVE: We aimed to show the feasibility of routinely implementing this type of hemodynamic monitoring during pancreatic surgery, and to evaluate its effects in terms of perioperative fluid management and postoperative outcomes. METHODS: All patients undergoing pancreatic surgery at a university hospital during two successive 12 months periods were included in this retrospective cohort analysis. Twelve months after the implementation of a standard operating procedure for a goal directed therapy (GDT, N = 45) using a pulse contour automated hemodynamic device were compared with a similar period before its use (control, N = 31) regarding mortality, length of hospital and ICU stay, postoperative complications and the use of fluids and vasopressors. RESULTS: Overall, 76 patients were analysed. Significantly less crystalloids were used in the GDT group. Patients receiving GDT showed significantly fewer severe complications (insufficiency of intestinal anastomosis: 0 vs. 5 (P = 0.0053) and renal failure: 0 vs. 4 (P = 0.0133). Mortality for pancreatic surgery was 1 vs. 3 patients, (P = 0.142), and length of stay (LOS) in the intensive care unit (ICU) was 4.38 ± 3.63 vs. 6.87 ± 10.02 (P= 0.0964) days. Use of blood products was significantly less within the GDT group. CONCLUSIONS: Implementation of a SOP for a GDT in the daily routine using flow-related parameters is feasible and is associated with better outcomes in pancreatic surgery.

Combination of STOP-Bang Score with Mallampati Score fails to improve specificity in the prediction of sleep-disordered breathing.

BACKGROUND: Sleep-disordered breathing (SDB) is closely associated with perioperative complications. STOP-Bang score was validated for preoperative screening of SDB. However, STOP-Bang Score lacks adequately high specificity. We aimed to improve it by combining it with the Mallampati Score. METHODS: The study included 347 patients, in which we assessed both STOP-Bang and Mallampati scores. Overnight oxygen saturation was measured to calculate ODI4%. We calculated the sensitivity and specificity for AHI and ODI4% of both scores separately and in combination. RESULTS: We found that STOP-Bang Score ≥3 was present in 71%, ODI≥5/h (AHI ≥5/h) in 42.6% (39.3%) and ODI≥15/h (AHI ≥15/h) in 13.5% (17.8%). For ODI4%≥5/h (AHI ≥5/h) we observed in men a response rate for sensitivity and specificity of STOP-Bang of 94.5% and 17.1% (90.9% and 12.5%) and in women 66% and 51% (57.8% and 46.9%). For ODI4%≥15/h (AHI≥15/h) it was 92% and 12% (84.6% and 10.3%) and 93% and 49% (75% and 49.2%). For ODI4%≥5 (AHI≥5) sensitivity and specificity of Mallampati score were in men 38.4% and 78.6% (27.3% and 68.2%) and in women 25% and 82.7% (21.9% and 81.3%), for ODI≥15 (AHI ≥15/h) 38.5% and 71.8% (26.9% and 69.2%) and 33.3% and 81.4% (17.9% and 79.6%). In combination, for ODI4%≥15/h, we found sensitivity in men to be 92.3% and in women 93.3%, specificity 10.3% and 41.4%. CONCLUSIONS: STOP-Bang Score combined with Mallampati Score fails to increase specificity. Low specificity should be considered when using both scores for preoperative screening of SDB.

Supplemental Interscalene Blockade to General Anesthesia for Shoulder Arthroscopy: Effects on Fast Track Capability, Analgesic Quality, and Lung Function.

BACKGROUND: After shoulder surgery performed in patients with interscalene nerve block (without general anesthesia), fast track capability and postoperative pain management in the PACU are improved compared with general anesthesia alone. However, it is not known if these evidence-based benefits still exist when the interscalene block is combined with general anesthesia. METHODS: We retrospectively analyzed a prospective cohort data set of 159 patients undergoing shoulder arthroscopy with general anesthesia alone (n = 60) or combined with an interscalene nerve block catheter (n = 99) for fast track capability time. Moreover, comparisons were made for VAS scores, analgesic consumption in the PACU, pain management, and lung function measurements. RESULTS: The groups did not differ in mean time to fast track capability (22 versus 22 min). Opioid consumption in PACU was significantly less in the interscalene group, who had significantly better VAS scores during PACU stay. Patients receiving interscalene blockade had a significantly impaired lung function postoperatively, although this did not affect postoperative recovery and had no impact on PACU times. CONCLUSION: The addition of interscalene block to general anesthesia for shoulder arthroscopy did not enhance fast track capability. Pain management and VAS scores were improved in the interscalene nerve block group.

Impact of regional femoral nerve block during general anesthesia for hip arthoplasty on blood pressure, heart rate and pain control: A randomized controlled study.

BACKGROUND: Adequate pain management is essential for preventing hemodynamic instability which can affect the perfusion of vital organs during the perioperative period, particularly in geriatric patients. For hip arthroplasty, peripheral nerve block is frequently used, limiting the adverse effects of opioid and non-opioid analgesics. OBJECTIVE: The aim was to survey the impact of a supplementary single shot femoral nerve block (FNB) on hemodynamic stability and pain level. METHODS: After registration at German Clinical Trial Register (DRKS-ID): DRKS00000752. and Ethics Committee approval (University Hospital of Marburg), 80 patients who underwent elective hip surgery were included. Half of them were randomly assigned to receive a FNB followed by general anesthesia; a control group received only general anesthesia as standard procedure (STD). Blood pressure and heart rate were measured and recorded every five minutes during surgery and stay at the postanesthesia care unit (PACU). RESULTS: Fifty-two patients were included for statistical analysis. The FNB group had significantly lower systolic blood pressures during and after surgery and lower diastolic blood pressure postoperatively, heart rate, as well as opioid and non-steroidal anti-inflammatory consumption. CONCLUSIONS: Femoral nerve block improved perioperative hemodynamic stability mostly likely attributable to an overall reduced sympathico adrenergic tone.

Separation of stimulating catheters for continuous peripheral regional anesthesia during their removal - two case reports and a critical appraisal of the use of steel-coil containing stimulating catheters.

PURPOSE: Stimulating catheters are widely used for continuous peripheral nerve block techniques in regional anesthesia. The incidence of reported complications is somewhat similar to that for non-stimulating catheters. However, as many stimulating catheters contain a coiled steel wire for optimal stimulation, they may cause specific complications. CLINICAL FEATURES: In this report, we present two cases of complicated removals of stimulating catheters. During both removals, a part of the metal wire was left "decoiled" next to the supraclavicular and interscalene plexus, respectively. The strategies used to determine steel wire localization and a description of the successful removal of these steel wires are included in this report. CONCLUSION: Catheter separation and problems with residual metal wire components of stimulating catheters seem to be a rare but specific problem during removal. Anesthesiologists should strictly avoid catheter shearing during insertion, adhere to the manufacturer's instructions, and take care during catheter removal. Manufacturers should focus on technical solutions to avoid rare but relevant complications such as catheter tip decoiling and separation of stimulating catheters during removal.

Compound imaging technology and echogenic needle design: effects on needle visibility and tissue imaging.

INTRODUCTION: Needle visualization in ultrasound-guided regional anesthesia can be improved by using needles of echogenic design with higher rate of reflection of ultrasound waves. Imaging solutions such as compound imaging might further improve imaging of both needle and tissue; these effects have not yet been studied. We hypothesized that compound imaging would significantly improve needle visibility, regardless of the insertion angle or needle type used. The effects of compound imaging on needle artifacts and tissue imaging were also investigated. METHODS: A total of 200 video clips of in-plane needle insertions were obtained in embalmed cadavers with a conventional needle and an echogenic needle at 5 different insertion angles, with both conventional B-mode ultrasound imaging and compound imaging technology. Visibility of the needle shaft and needle tip as well as the needle artifact rate were assessed by a blinded investigator on a 4-point ordinal scale. The effects on tissue image quality and speckle artifacts were also assessed. Stepwise linear regression was performed to differentiate effects on needle visibility scores. RESULTS: Imaging of the needle shaft and tip was significantly enhanced when compound imaging technology was used (P < 0.0001). Use of echogenically designed needles or shallow needle insertion angles improved visibility of both shaft and tip (both P < 0.0001). With compound imaging, there are fewer needle artifacts, and tissue imaging quality and speckle artifact rate are significantly improved. CONCLUSIONS: Compound imaging technology enhances needle imaging with both echogenic and conventional needles. Tissue imaging and speckle artifacts are also optimized. Echogenic needle design results in better needle visibility scores in both B-mode and compound imaging.