Chronic pain patients and time to sustained acceptable pain scores after major surgery - A retrospective registry analysis.

STUDY OBJECTIVE: We tested the hypothesis that pre-existing chronic pain is associated with prolonged time to reach sustained acceptable pain scores after major surgery. DESIGN: Retrospective study using the German Network for Safety in Regional Anaesthesia and Acute Pain Therapy registry. SETTING: Operating rooms and surgical wards. PATIENTS: 107,412 patients recovering from major surgery who were cared for by an acute pain service. 3.3% of the treatments were in patients who reported chronic pain with functional or psychological impairment. INTERVENTIONS AND MEASUREMENT: We compared time to sustained adequacy of postoperative pain control defined by numeric rating scores <4 at rest and with movement in patients with and without chronic pain using an adjusted cox proportional hazard regression model and Kaplan-Meier analysis. The observation period was censored at 10 days and propensity score matching was used as a sensitivity analysis. MAIN RESULTS: Postoperative pain at rest took significantly longer to resolve in patients with chronic pain than in those without (adjusted hazard ratio HR 1.42, 95% CI 1.36-1.49, P < 0.001). Postoperative pain with movement took even longer to resolve in patients with chronic pain (adjusted HR 1.65, 95%CI 1.56-1.75, P < 0.001). CONCLUSIONS: Patients with chronic pain sustain more surgical pain than those without, and the pain takes longer to resolve. Clinicians providing postoperative pain management should consider the special needs of chronic pain patients.

Quantification of exhaled propofol is not feasible during single-lung ventilation using double-lumen tubes: A multicenter prospective observational trial.

BACKGROUND: Volatile propofol can be measured in exhaled air and correlates to plasma concentrations with a time delay. However, the effect of single-lung ventilation on exhaled propofol is unclear. Therefore, our goal was to evaluate exhaled propofol concentrations during single-lung compared to double-lung ventilation using double-lumen tubes. METHODS: In a first step, we quantified adhesion of volatile propofol to the inner surface of double-lumen tubes during double- and single-lumen ventilation in vitro. In a second step, we enrolled 30 patients scheduled for lung surgery in two study centers. Anesthesia was provided with propofol and remifentanil. We utilized left-sided double-lumen tubes to separately ventilate each lung. Exhaled propofol concentrations were measured at 1-min intervals and plasma for propofol analyses was sampled every 20 min. To eliminate the influence of dosing on volatile propofol concentration, exhalation rate was normalized to plasma concentration. RESULTS: In-vitro ventilation of double-lumen tubes resulted in increasing propofol concentrations at the distal end of the tube over time. In vitro clamping the bronchial lumen led to an even more pronounced increase (Δ AUC +62%) in propofol gas concentration over time. Normalized propofol exhalation during lung surgery was 31% higher during single-lung compared to double-lung ventilation. CONCLUSION: During single-lung ventilation, propofol concentration in exhaled air, in contrast to our expectations, increased by approximately one third. However, this observation might not be affected by change in perfusion-ventilation during single-lung ventilation but rather arises from reduced propofol absorption on the inner surface area of the double-lumen tube. Thus, it is only possible to utilize exhaled propofol concentration to a limited extent during single-lung ventilation. REGISTRATION OF CLINICAL TRIAL: DRKS-ID DRKS00014788 (www.drks.de).

Increasing the reflection efficiency of the Sedaconda ACD-S by heating and cooling the anaesthetic reflector: a bench study using a test lung.

BACKGROUND: As volatile anaesthetic gases contribute to global warming, improving the efficiency of their delivery can reduce their environmental impact. This can be achieved by rebreathing from a circle system, but also by anaesthetic reflection with an open intensive care ventilator. We investigated whether the efficiency of such a reflection system could be increased by warming the reflector during inspiration and cooling it during expiration (thermocycling). METHODS: The Sedaconda-ACD-S (Sedana Medical, Danderyd, Sweden) was connected between an intensive care ventilator and a test lung. Liquid isoflurane was infused into the device at 0.5, 1.0, 2.0 and 5.0 mL/h; ventilator settings were 500 mL tidal volume, 12 bpm, 21% oxygen. Isoflurane concentrations were measured inside the test lung after equilibration. Thermocycling was achieved by heating the breathing gas in the inspiratory hose to 37 °C via a heated humidifier without water. Breathing gas expired from the test lung was cooled to 14 °C before reaching the ACD-S. In the test lung, body temperature pressure saturated conditions prevailed. Isoflurane concentrations and reflective efficiency were compared between thermocycling and control conditions. RESULTS: With thermocycling higher isoflurane concentrations in the test lung were measured for all infusion rates studied. Interpolation of data showed that for achieving 0.4 (0.6) Vol% isoflurane, the infusion rate can be reduced from 1.2 to 0.7 (2.0 to 1.2) mL/h or else to 56% (58%) of control. CONCLUSION: Thermocycling of the anaesthetic gas considerably increases the efficiency of the anaesthetic reflector and reduces anaesthetic consumption by almost half in a test lung model. Given that cooling can be miniaturized, this method carries a potential for further saving anaesthetics in clinical practice in the operating theatre as well as for inhaled sedation in the ICU.

Resveratrol therapy improves liver function via estrogen-receptors after hemorrhagic shock in rats.

BACKGROUND: Resveratrol may improve organ dysfunction after experimental hemorrhagic or septic shock, and some of these effects appear to be mediated by estrogen receptors. However, the influence of resveratrol on liver function and hepatic microcirculation after hemorrhagic shock is unknown, and a presumed mediation via estrogen receptors has not been investigated in this context. METHODS: Male Sprague-Dawley rats (200-300g, n = 14/group) underwent hemorrhagic shock for 90 min (MAP 35±5 mmHg) and were resuscitated with shed blood and Ringer's solution. Animals were treated intravenously with vehicle (1% EtOH), resveratrol (0.2 mg/kg), the unselective estrogen receptor antagonist ICI 182,780 (0.05 mg/kg) or resveratrol + ICI 182,780 prior to retransfusion. Sham-operated animals did not undergo hemorrhage but were treated likewise. After 2 hours of reperfusion, liver function was assessed either by plasma disappearance rate of indocyanine green (PDRICG) or evaluation of hepatic perfusion and hepatic integrity by intravital microscopy, serum enzyme as well as cytokine levels. RESULTS: Compared to vehicle controls, administration of resveratrol significantly improved PDRICG, hepatic perfusion index and hepatic integrity after hemorrhagic shock. The co-administration of ICI 182,780 completely abolished the protective effect only with regard to liver function. CONCLUSIONS: This study shows that resveratrol may improve liver function and hepatocellular integrity after hemorrhagic shock in rats; estrogen receptors mediate these effects at least partially.

Exhaled Aldehydes as Biomarkers for Lung Diseases: A Narrative Review.

Breath analysis provides great potential as a fast and non-invasive diagnostic tool for several diseases. Straight-chain aliphatic aldehydes were repeatedly detected in the breath of patients suffering from lung diseases using a variety of methods, such as mass spectrometry, ion mobility spectrometry, or electro-chemical sensors. Several studies found increased concentrations of exhaled aldehydes in patients suffering from lung cancer, inflammatory and infectious lung diseases, and mechanical lung injury. This article reviews the origin of exhaled straight-chain aliphatic aldehydes, available detection methods, and studies that found increased aldehyde exhalation in lung diseases.

Distinct Patterns of Blood Cytokines Beyond a Cytokine Storm Predict Mortality in COVID-19.

BACKGROUND: COVID-19 comprises several severity stages ranging from oligosymptomatic disease to multi-organ failure and fatal outcomes. The mechanisms why COVID-19 is a mild disease in some patients and progresses to a severe multi-organ and often fatal disease with respiratory failure are not known. Biomarkers that predict the course of disease are urgently needed. The aim of this study was to evaluate a large spectrum of established laboratory measurements. PATIENTS AND METHODS: Patients from the prospective PULMPOHOM and CORSAAR studies were recruited and comprised 35 patients with COVID-19, 23 with conventional pneumonia, and 28 control patients undergoing elective non-pulmonary surgery. Venous blood was used to measure the serum concentrations of 79 proteins by Luminex multiplex immunoassay technology. Distribution of biomarkers between groups and association with disease severity and outcomes were analyzed. RESULTS: The biomarker profiles between the three groups differed significantly with elevation of specific proteins specific for the respective conditions. Several biomarkers correlated significantly with disease severity and death. Uniform manifold approximation and projection (UMAP) analysis revealed a significant separation of the three disease groups and separated between survivors and deceased patients. Different models were developed to predict mortality based on the baseline measurements of several protein markers. A score combining IL-1ra, IL-8, IL-10, MCP-1, SCF and CA-9 was associated with significantly higher mortality (AUC 0.929). DISCUSSION: Several newly identified blood markers were significantly increased in patients with severe COVID-19 (AAT, EN-RAGE, myoglobin, SAP, TIMP-1, vWF, decorin) or in patients that died (IL-1ra, IL-8, IL-10, MCP-1, SCF, CA-9). The use of established assay technologies allows for rapid translation into clinical practice.

Comparison of isoflurane and propofol sedation in critically ill COVID-19 patients-a retrospective chart review.

PURPOSE: In this retrospective study, we compared inhaled sedation with isoflurane to intravenous propofol in invasively ventilated COVID-19 patients with ARDS (Acute Respiratory Distress Syndrome). METHODS: Charts of all 20 patients with COVID-19 ARDS admitted to the ICU of a German University Hospital during the first wave of the pandemic between 22/03/2020 and 21/04/2020 were reviewed. Among screened 333 days, isoflurane was used in 97 days, while in 187 days, propofol was used for 12 h or more. The effect and dose of these two sedatives were compared. Mixed sedation days were excluded. RESULTS: Patients' age (median [interquartile range]) was 64 (60-68) years. They were invasively ventilated for 36 [21-50] days. End-tidal isoflurane concentrations were high (0.96 ± 0.41 Vol %); multiple linear regression yielded the ratio (isoflurane infusion rate)/(minute ventilation) as the single best predictor. Infusion rates were decreased under ECMO (3.5 ± 1.4 versus 7.1 ± 3.2 ml∙h-1; p < 0.001). In five patients, the maximum recommended dose of propofol of 4 mg∙hour-1∙kg-1ABW was exceeded on several days. On isoflurane compared to propofol days, neuro-muscular blocking agents (NMBAs) were used less frequently (11% versus 21%; p < 0.05), as were co-sedatives (7% versus 31%, p < 0.001); daily opioid doses were lower (720 [720-960] versus 1080 [720-1620] mg morphine equivalents, p < 0.001); and RASS scores indicated deeper levels of sedation (- 4.0 [- 4.0 to - 3.0] versus - 3.0 [- 3.6 to - 2.5]; p < 0.01). CONCLUSION: Isoflurane provided sufficient sedation with less NMBAs, less polypharmacy and lower opioid doses compared to propofol. High doses of both drugs were needed in severely ill COVID-19 patients.

Association of Perioperative Regional Analgesia with Postoperative Patient-Reported Pain Outcomes and Opioid Requirements: Comparing 22 Different Surgical Groups in 23,911 Patients from the QUIPS Registry.

(1) Background: In many surgical procedures, regional analgesia (RA) techniques are associated with improved postoperative analgesia compared to systemic pain treatment. As continuous RA requires time and experienced staff, it would be helpful to identify settings in which continuous RA has the largest benefit. (2) Methods: On the basis of 23,911 data sets from 179 German and Austrian hospitals, we analyzed the association of perioperative RA with patient-reported pain intensity, functional impairment of movement, nausea and opioid use for different surgeries. Regression analyses adjusted for age, sex and preoperative pain were performed for each surgery and the following groups: patients receiving continuous RA (surgery and ward; RA++), RA for surgery only (RA+-) and patients receiving no RA (RA--). (3) Results: Lower pain scores in the RA++ compared to the RA-- group were observed in 13 out of 22 surgeries. There was no surgery where pain scores for RA++ were higher than for RA--. If maximal pain, function and side effects were combined, the largest benefit of continuous RA (RA++) was observed in laparoscopic colon and sigmoid surgery, ankle joint arthrodesis, revision (but not primary) surgery of hip replacement, open nephrectomy and shoulder surgery. The benefit of RA+- was lower than that of RA++. (4) Discussion: The additional benefit of RA for the mentioned surgeries is larger than in many other surgeries in clinical routine. The decision to use RA in a given surgery should be based on the expected pain intensity without RA and its additional benefits.

Reflection Versus Rebreathing for Administration of Sevoflurane During Minor Gynecological Surgery.

BACKGROUND: Contemporary anesthetic circle systems, when used at low fresh gas flows (FGF) to allow rebreathing of anesthetic, lack the ability for rapid dose titration. The small-scale anesthetic reflection device Anaesthetic Conserving Device (50mL Version; AnaConDa-S) permits administration of volatile anesthetics with high-flow ventilators. We compared washin, washout, and sevoflurane consumption using AnaConDa-S versus a circle system with low and minimal FGF. METHODS: Forty patients undergoing breast surgery were randomized to receive 0.5 minimal alveolar concentration (MAC) sevoflurane with AnaConDa-S (21 patients, reflection group) or with a circle system (low flow: FGF = 0.2 minute ventilation [V'E], 9 patients; or minimal flow: 0.1 V'E, 10 patients). In the reflection group, syringe pump boluses were given for priming and washin; to simulate an open system, the FGF of the anesthesia ventilator was set to 18 L·min-1 with the soda lime removed. In the other groups, the FGF was increased for washin (1 V'E for 8 minutes) and washout (3 V'E). For all patients, tidal volume was 7 mL·kg-1 and the respiratory rate adjusted to ensure normoventilation. Analgesia was attained with remifentanil 0.3 µg·kg-1·min-1. Sevoflurane consumption was compared between the reflection group and the low- and minimal-flow groups, respectively, using a post hoc test (Fisher Least Significant Difference). To compare washin and washout (half-life), the low- and minimal-flow groups were combined. RESULTS: Sevoflurane consumption was reduced in the reflection group (9.4 ± 2.0 vs 15.0 ± 3.5 [low flow, P < .001] vs 11.6 ± 2.3 mL·MAC h-1 [minimal flow, P = .02]); washin (33 ± 15 vs 49 ± 12 seconds, P = .001) and washout (28 ± 15 vs 55 ± 19 seconds, P < .001) times were also significantly shorter. CONCLUSIONS: In this clinical setting with short procedures, low anesthetic requirements, and low tidal volumes, AnaConDa-S decreased anesthetic consumption, washin, and washout times compared to a circle system.

Exhaled Volatile Organic Compounds during Inflammation Induced by TNF-α in Ventilated Rats.

Systemic inflammation alters the composition of exhaled breath, possibly helping clinicians diagnose conditions such as sepsis. We therefore evaluated changes in exhaled breath of rats given tumor necrosis factor-alpha (TNF-α). Thirty male Sprague-Dawley rats were randomly assigned to three groups (n = 10 each) with intravenous injections of normal saline (control), 200 µg·kg-1 bodyweight TNF-α (TNF-α-200), or 600 µg·kg-1 bodyweight TNF-α (TNF-α-600), and were observed for 24 h or until death. Animals were ventilated with highly-purified synthetic air to analyze exhaled air by multicapillary column-ion mobility spectrometry. Volatile organic compounds (VOCs) were identified from a database. We recorded blood pressure and cardiac output, along with cytokine plasma concentrations. Control rats survived the 24 h observation period, whereas mean survival time decreased to 22 h for TNF-α-200 and 23 h for TNF-α-600 rats. Mean arterial pressure decreased in TNF-α groups, whereas IL-6 increased, consistent with mild to moderate inflammation. Hundreds of VOCs were detected in exhalome. P-cymol increased by a factor-of-two 4 h after injection of TNF-α-600 compared to the control and TNF-α-200. We found that 1-butanol and 1-pentanol increased in both TNF-α groups after 20 h compared to the control. As breath analysis distinguishes between two doses of TNF-α and none, we conclude that it might help clinicians identify systemic inflammation.

Evaluating the Use of Circulating MicroRNA Profiles for Lung Cancer Detection in Symptomatic Patients.

Importance: The overall low survival rate of patients with lung cancer calls for improved detection tools to enable better treatment options and improved patient outcomes. Multivariable molecular signatures, such as blood-borne microRNA (miRNA) signatures, may have high rates of sensitivity and specificity but require additional studies with large cohorts and standardized measurements to confirm the generalizability of miRNA signatures. Objective: To investigate the use of blood-borne miRNAs as potential circulating markers for detecting lung cancer in an extended cohort of symptomatic patients and control participants. Design, Setting, and Participants: This multicenter, cohort study included patients from case-control and cohort studies (TREND and COSYCONET) with 3102 patients being enrolled by convenience sampling between March 3, 2009, and March 19, 2018. For the cohort study TREND, population sampling was performed. Clinical diagnoses were obtained for 3046 patients (606 patients with non-small cell and small cell lung cancer, 593 patients with nontumor lung diseases, 883 patients with diseases not affecting the lung, and 964 unaffected control participants). No samples were removed because of experimental issues. The collected data were analyzed between April 2018 and November 2019. Main Outcomes and Measures: Sensitivity and specificity of liquid biopsy using miRNA signatures for detection of lung cancer. Results: A total of 3102 patients with a mean (SD) age of 61.1 (16.2) years were enrolled. Data on the sex of the participants were available for 2856 participants; 1727 (60.5%) were men. Genome-wide miRNA profiles of blood samples from 3046 individuals were evaluated by machine-learning methods. Three classification scenarios were investigated by splitting the samples equally into training and validation sets. First, a 15-miRNA signature from the training set was used to distinguish patients diagnosed with lung cancer from all other individuals in the validation set with an accuracy of 91.4% (95% CI, 91.0%-91.9%), a sensitivity of 82.8% (95% CI, 81.5%-84.1%), and a specificity of 93.5% (95% CI, 93.2%-93.8%). Second, a 14-miRNA signature from the training set was used to distinguish patients with lung cancer from patients with nontumor lung diseases in the validation set with an accuracy of 92.5% (95% CI, 92.1%-92.9%), sensitivity of 96.4% (95% CI, 95.9%-96.9%), and specificity of 88.6% (95% CI, 88.1%-89.2%). Third, a 14-miRNA signature from the training set was used to distinguish patients with early-stage lung cancer from all individuals without lung cancer in the validation set with an accuracy of 95.9% (95% CI, 95.7%-96.2%), sensitivity of 76.3% (95% CI, 74.5%-78.0%), and specificity of 97.5% (95% CI, 97.2%-97.7%). Conclusions and Relevance: The findings of the study suggest that the identified patterns of miRNAs may be used as a component of a minimally invasive lung cancer test, complementing imaging, sputum cytology, and biopsy tests.

Residual volatile anesthetics after workstation preparation and activated charcoal filtration.

BACKGROUND: Volatile anesthetics potentially trigger malignant hyperthermia crises in susceptible patients. We therefore aimed to identify preparation procedures for the Draeger Primus that minimize residual concentrations of desflurane and sevoflurane with and without activated charcoal filtration. METHODS: A Draeger Primus test workstation was primed with 7% desflurane or 2.5% sevoflurane for 2 hours. Residual anesthetic concentrations were evaluated with five preparation procedures, three fresh gas flow rates, and three distinct applications of activated charcoal filters. Finally, non-exchangeable and autoclaved parts of the workstation were tested for residual emission of volatile anesthetics. Concentrations were measured by multicapillary column-ion mobility spectrometry with limits of detection/quantification being <1 part per billion (ppb) for desflurane and <2.5 ppb for sevoflurane. RESULTS: The best preparation procedure included a flushing period of 10 minutes between removal and replacement of all parts of the ventilator circuit which immediately produced residual concentrations <5 ppm. A fresh gas flow of 10 L/minute reduced residual concentration as effectively as 18 L/minute, whereas flows of 1 or 5 L/minute slowed washout. Use of activated charcoal filters immediately reduced and maintained residual concentrations <5 ppm for up to 24 hours irrespective of previous workstation preparation. The fresh gas hose, circle system, and ventilator diaphragm emitted traces of volatile anesthetics. CONCLUSION: In elective cases, presumably safe concentrations can be obtained by a 10-minute flush at ≥10 L/minute between removal and replacement all components of the airway circuit. For emergencies, we recommend using an activated charcoal filter.

[Progressive muscle relaxation in postoperative pain therapy]. / Progressive Muskelrelaxation in der postoperativen Schmerztherapie.

BACKGROUND: Early and optimal treatment of postoperative pain based on a multimodal treatment concept is very important so that subsequent chronification can be avoided. OBJECTIVES: This study investigated the influence of progressive muscle relaxation on the sensation of pain and the need for analgesics after orthopedic interventions. MATERIALS AND METHODS: This nonrandomized pilot study tested 104 patients in the Clinic of Orthopedics at the Saarland University Medical Center in Homburg, Germany. The patients underwent total endoprosthesis (TEP) of the or the knee or spine surgery (laminectomy), and they had the option of choosing to use the technique of progressive muscle relaxation. All patients completed a questionnaire on the first, fourth, and ninth postoperative day. Data were collected on the maximum and minimum intensity of pain, duration of strong pain, length of hospital stay, and use of pain medication. These were compared by means of t tests for the group with progressive muscle relaxation and the group without progressive muscle relaxation. RESULTS: No significant difference was observed between the two groups regarding pain sensation analgesic dosage. There was a tendency for the length of hospital stay to be shorter in the group with progressive muscle relaxation. CONCLUSION: The positive effect of progressive muscle relaxation cannot be confirmed on the basis of the study data. Owing to the varying study design and implementation as well as the inclusion of heterogeneous patient groups, no conclusion can be drawn at present regarding the effectiveness of progressive muscle relaxation in common practice; therefore, further research is necessary.

Study of melatonin-mediated effects on various hepatic inflammatory responses stimulated by IL-6 in a new HepG2-on-a-chip platform.

Hepatocytes exhibit diverse reactions upon stimulation with the interleukin IL-6, mainly in the context of inflammation and energy metabolism. Melatonin has been shown to exert pleiotropic protective actions, such as anti-inflammation and anti-oxidative stress on many cell- and organ-types. The key role of the liver to maintain homeostasis and metabolic regulation prompted us to evaluate the direct modification of IL-6-induced alterations in HepG2 cells in a chip by melatonin. IL-6 administration was followed by the reduced expression and activity of MRP2, a loss of CYP1A activity, and the decline of PXR expression. Other effects were the induction of acute phase responses (reduced albumin production as well as increased CRP and hepcidin expression) and lowered expression of CREB3L3. IL-6 affected also the mitochondrial membrane potential together with elevated mitochondrial superoxide generation, and glycogen deposition was reduced. Melatonin counteracted all observed IL-6-induced alterations except the rise in CRP release and CYP1A activity. Altogether, this new in vitro model can be applied to investigate hepatic inflammatory responses stimulated by IL-6, and these results indicate that hepatocellular inflammatory responses to IL-6 are mitigated by melatonin.

Regional vs. General Anesthesia for Total Knee and Hip Replacement: An Analysis of Postoperative Pain Perception from the International PAIN OUT Registry.

BACKGROUND: Total hip and knee replacements are common surgeries, and an optimal pain treatment is essential for early rehabilitation. Since data from randomized controlled trials on the use of regional anesthesia in joint replacements of the lower extremities are conflicting, we analyzed the international PAIN OUT registry for comparison of regional anesthesia vs. general anesthesia regarding pain and morphine consumption on the first postoperative day. METHODS: International Classification of Diseases-9 (ICD-9) codes were used to identify 2,346 cases of knee arthroplasty and 2,315 cases of hip arthroplasty between 2010 and 2016 from the PAIN OUT registry. Those were grouped according to anesthesia provided (general, regional, and a combination of both). On the first day after surgery, pain levels and opioid consumption were compared. Adjusted odds ratios (ORs [and 95% confidence intervals (CIs)]) were calculated with logistic regression, and propensity matching was used as a sensitivity analysis. RESULTS: After adjustment for confounders, regional anesthesia was associated with reduced opioid consumption (OR 0.20 [95% CI 0.13 to 0.30], P < 0.001) and less pain (OR 0.53 [95% CI 0.36 to 0.78], P = 0.001) than was general anesthesia in knee surgery. In hip surgery, regional anesthesia was only associated with reduced opioid consumption (OR 0.17 [95% CI 0.11 to 0.26], P < 0.001), whereas pain was comparable (OR 1.23 [95% CI 0.94 to 1.61], P = 0.1). Results from a propensity-matched sensitivity analysis were similar. CONCLUSION: In total knee arthroplasty, regional anesthesia was associated with less pain and lower opioid consumption. In total hip arthroplasty, regional anesthesia was associated with lower opioid consumption, but not with reduced pain levels.

Halving the volume of AnaConDa: initial clinical experience with a new small-volume anaesthetic reflector in critically ill patients-a quality improvement project.

AnaConDa-100 ml (ACD-100, Sedana Medical, Uppsala, Sweden) is well established for inhalation sedation in the intensive care unit. But because of its large dead space, the system can retain carbon dioxide (CO2) and increase ventilatory demands. We therefore evaluated whether AnaConDa-50 ml (ACD-50), a device with half the internal volume, reduces CO2 retention and ventilatory demands during sedation of invasively ventilated, critically ill patients. Ten patients participated in this cross-over protocol. After sedation with isoflurane via ACD-100 for 24 h, the 5-h observation period started. During the first hour, ACD-100 was used; for the next 2 h, ACD-50; and for the last 2 h, ACD-100 was used again. Sedation was titrated to Richmond Agitation and Sedation Scale (RASS) score - 3 to - 4 and a processed electroencephalogram (Narcotrend Index, Narcotrend-Gruppe, Hannover, Germany) was recorded. Minute ventilation, CO2 elimination, and isoflurane consumption were compared. All patients were deeply sedated (Narcotrend Index, mean ± SD: 38 ± 10; RASS scores - 3 to - 5) and breathed spontaneously with pressure support throughout the observation period. Infusion rates of isoflurane and opioid, either remifentanil or sufentanil, as well as ventilator settings were unchanged. Minute ventilation and end-tidal CO2 were significantly reduced with the ACD-50, respiratory rate remained unchanged, and tidal volume decreased by 66 ± 43 ml. End-tidal isoflurane concentrations were also slightly reduced while haemodynamic measures remained constant. The ACD-50 reduces the tidal volume needed to eliminate carbon dioxide without augmenting isoflurane consumption.

Prolonged Catheter Use and Infection in Regional Anesthesia: A Retrospective Registry Analysis.

BACKGROUND: Prolonged catheter use is controversial because of the risk of catheter-related infection, but the extent to which the risk increases over time remains unknown. We thus assessed the time-dependence of catheter-related infection risk up to 15 days. METHODS: Our analysis was based on the German Network for Regional Anesthesia, which includes 25 centers. We considered 44,555 patients who had surgery between 2007 and 2014 and had continuous regional anesthesia as well as complete covariable details. Cox regression analysis was performed and adjusted for confounding covariables to examine the relationship between catheter duration and probability of infection-free catheter use. RESULTS: After adjustment for confounding factors, the probability of infection-free catheter use decreases with each day of peripheral and epidural catheter use. In peripheral catheters, it was 99% at day 4 of catheter duration, 96% at day 7, and 73% at day 15. In epidural catheters, it was 99% at day 4 of catheter duration, 95% at day 7, and 73% at day 15. Only 31 patients (0.07%) had severe infections that prompted surgical intervention. Among these were five catheters that initially had only mild or moderate signs of infection and were left in situ; all progressed to severe infections. CONCLUSIONS: Infection risk in catheter use increases over time, especially after four days. Infected catheters should be removed as soon as practical. VISUAL ABSTRACT: An online visual overview is available for this article at http://links.lww.com/ALN/B683.

Volumetric and reflective device dead space of anaesthetic reflectors under different conditions.

Inhalation sedation is increasingly performed in intensive care units. For this purpose, two anaesthetic reflectors, AnaConDa™ and Mirus™ are commercially available. However, their internal volume (100 ml) and possible carbon dioxide reflection raised concerns. Therefore, we compared carbon dioxide elimination of both with a heat moisture exchanger (HME, 35 ml) in a test lung model. A constant flow of carbon dioxide was insufflated into the test lung, ventilated with 500 ml, 10 breaths per minute. HME, MIRUS and AnaConDa were connected successively. Inspired (insp-CO2) and end-tidal carbon dioxide concentrations (et-CO2) were measured under four conditions: ambient temperature pressure (ATP), body temperature pressure saturated (BTPS), BTPS with 0.4 Vol% (ISO-0.4), and 1.2 Vol% isoflurane (ISO-1.2). Tidal volume increase to maintain normocapnia was also determined. Insp-CO2 was higher with AnaConDa compared to MIRUS and higher under ATP compared to BTPS. Isoflurane further decreased insp-CO2 and abolished the difference between AnaConDa and MIRUS. Et-CO2 showed similar effects. In addition to volumetric dead space, reflective dead space was determined as 198 ± 6/58 ± 6/35 ± 0/25 ± 0 ml under ATP/BTPS/ISO-0.4/ISO-1.2 conditions for AnaConDa, and 92 ± 6/25 ± 0/25 ± 0/25 ± 0 ml under the same conditions for MIRUS, respectively. Under BTPS conditions and with the use of moderate inhaled agent concentrations, reflective dead space is small and similar between the two devices.