Rebounds of sevoflurane concentration during simulated trigger-free pediatric and adult anesthesia.

BACKGROUND: In trigger-free anesthesia a volatile anesthetic concentration of 5 parts per million (ppm) should not be exceeded. According to European Malignant Hyperthermia Group (EMHG) guideline, this may be achieved by removing the vapor, changing the anesthetic breathing circuit and renewing the soda lime canister followed by flushing with O2 or air for a workstation specific time. Reduction of the fresh gas flow (FGF) or stand-by modes are known to cause rebound effects. In this study, simulated trigger-free pediatric and adult ventilation was carried out on test lungs including ventilation maneuvers commonly used in clinical practice. The goal of this study was to evaluate whether rebounds of sevoflurane develop during trigger-free anesthesia. METHODS: A Dräger® Primus® was contaminated with decreasing concentrations of sevoflurane for 120 min. Then, the machine was prepared for trigger-free anesthesia according to EMHG guideline by changing recommended parts and flushing the breathing circuits using 10 or 18 l⋅min- 1 FGF. The machine was neither switched off after preparation nor was FGF reduced. Simulated trigger-free ventilation was performed with volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) including various ventilation maneuvers like pressure support ventilation (PSV), apnea, decreased lung compliance (DLC), recruitment maneuvers, prolonged expiration and manual ventilation (MV). A high-resolution ion mobility spectrometer with gas chromatographic pre-separation was used to measure sevoflurane in the ventilation gas mixture in a 20 s interval. RESULTS: Immediately after start of simulated anesthesia, there was an initial peak of 11-18 ppm sevoflurane in all experiments. The concentration dropped below 5 ppm after 2-3 min during adult and 4-18 min during pediatric ventilation. Other rebounds of sevoflurane > 5 ppm occurred after apnea, DLC and PSV. MV resulted in a decrease of sevoflurane < 5 ppm within 1 min. CONCLUSION: This study shows that after guideline-compliant preparation for trigger-free ventilation anesthetic machines may develop rebounds of sevoflurane > 5 ppm during typical maneuvers used in clinical practice. The changes in rate and direction of internal gas flow during different ventilation modes and maneuvers are possible explanations. Therefore, manufacturers should provide machine-specific washout protocols or emphasize the use of active charcoal filters (ACF) for trigger-free anesthesia.

Incidence and characteristics of errors detected by a short team briefing in pediatric anesthesia.

BACKGROUND: In our institution, a modified WHO surgical safety checklist was implemented more than ten years ago. In retrospect, we noticed that pediatric anesthesia was underrepresented in our surgical safety checklist modification. Therefore, we added a standardized team briefing (pedSOAP-M) immediately before induction of anesthesia and hypothesized that the use of this checklist was effective to detect relevant errors with potentially harmful consequences. AIMS: The primary aim was to assess the incidence and characteristics of the detected errors, and the secondary aim was to identify factors influencing error detection. METHODS: This prospective observational study was performed between November 2020 and October 2021 in five operation rooms at the Children's Hospital of Hannover Medical School, Germany. The subcategories of the pedSOAP-M checklist were suction, oxygen, airway, pharmaceuticals, and monitoring. Demographic and procedure-related data and the briefing results were documented anonymously and undated, using a standardized case report form. RESULTS: We enrolled 1030 and analyzed 1025 patients (aged 0-18 years). Relevant errors were detected in 111 (10.8%) cases (suction 2.5%, oxygen 3.0%, airway 0.2%, pharmaceuticals 2.4%, monitoring 3.0%). In the pharmaceuticals subcategory, the most common error was entering a wrong patient weight into the perfusor syringe pumps. Experienced anesthetists detected significantly more errors than less experienced ones. CONCLUSION: The briefing tool pedSOAP-M was effective in detecting relevant errors with potentially harmful consequences. The presence of an experienced anesthetist was associated with a higher efficacy of the briefing. Particular attention should be given to entering patient weight into the anesthesia workstation and the perfusor syringe pumps.

The impact of modified fluid gelatin 4% in a balanced electrolyte solution on plasma osmolality in children-A noninterventional observational study.

BACKGROUND: Intravenous fluids for perioperative infusion therapy should be isotonic to maintain the body fluid homeostasis in children. Modified fluid gelatin 4% in a balanced electrolyte solution has a theoretical osmolarity of 284 mosmol L-1 , and a real osmolality of 264 mosmol kg H2 O-1 . Because both values are lower than those of 0.9% saline or plasma, gelatin would be expected to be hypotonic in-vitro and in-vivo. AIM: We thus hypothesized that the infusion of gelatin would be expected to decrease plasma osmolality. We performed an in-vitro experiment and an in-vivo study to evaluate the impact of gelatin on the osmolality in children. METHODS: In the in-vitro experiment, full blood samples were diluted with gelatin 4% or albumin (50 g L-1 ) from 0% (pure blood) to 100% (pure colloid), and the osmolality was measured by freezing-point depression. In the in-vivo study, blood gas analyses from children undergoing major pediatric surgery were collected before and after gelatin infusion, and the osmolality was calculated by a modified version of Zander's formula. RESULTS: In the in-vitro experiment, 65 gradually diluted blood samples from five volunteers (age 25-55 years) were analyzed. The dilution with gelatin caused no significant changes in osmolality between 0% and 100%. Compared with gelatin, the osmolality in the albumin group was significantly lower between 50% and 100% dilution (p < .05). In the in-vivo study, 221 children (age 21.4 ± 30 months) were included. After gelatin infusion, the osmolality increased significantly (mean change 4.3 ± 4.8 [95% CI 3.7-4.9] mosmol kg H2 O-1 ; p < .01) within a normal range. CONCLUSIONS: Gelatin in a balanced electrolyte solution has isotonic characteristics in-vitro and in-vivo, despite the low theoretical osmolarity, probably caused by the (unmeasured) negative charges in the gelatin molecules contributing to the plasma osmolality. For a better evaluation of the (real) tonicity of gelatin-containing solutions, we suggest to calculate the osmolality (mosmol kg H2 O-1 ) using Zander's formula. TRIAL REGISTRATION: ClinicalTrials.gov (ID: NCT02495285).

Modified fluid gelatin 4% for perioperative volume replacement in pediatric patients (GPS): Results of a European prospective noninterventional multicenter study.

INTRODUCTION: Modified fluid gelatin 4% is approved for use in children, but there is still a surprising lack of clinical studies including large numbers of pediatric patients. Therefore, we performed a European prospective noninterventional multicenter study to evaluate the use of a modified fluid gelatin 4% in saline (sal-GEL) or an acetate-containing balanced electrolyte solution (bal-GEL) in children undergoing major pediatric surgery. AIMS: The primary aim was to assess the indications and dosing of modified fluid gelatin, and the secondary aim was to assess the safety and efficacy, focusing, in particular, on routinely collected clinical parameters. METHODS: Children aged up to 12 years with ASA risk scores of I-III receiving sal-GEL or bal-GEL were followed perioperatively. Demographic data, surgical procedures performed, anesthesia, hemodynamic and laboratory data, adverse events, and adverse drug reactions were documented using a standardized case report form. RESULTS: 601 children that were investigated at 13 European pediatric centers from May 2015 to March 2020 (sal-GEL 20.1%, bal-GEL 79.9%; mean age 29.1 ± 38.6 (range 0-144) months; body weight 12.1 ± 10.5 (1.4-70) kg) were included in the analysis. The most frequent indications for GEL infusion were hemodynamic instability without bleeding (76.0%), crystalloids alone not being sufficient for hemodynamic stabilization (55.7%), replacement of preoperative deficit (26.0%), and significant bleeding (13.0%). Mean infused GEL volume was 13.0 ± 5.3 (2.4-37.5) ml kg-1 . The total dose was affected by age, with higher doses in younger patients. After gelatin infusion, mean arterial pressure increased (mean change 8.5 ± 7.3 [95% CI: 8 to 9.1] mmHg), and the hemoglobin concentrations decreased significantly (mean change -1.1 ± 1.8 [95% CI: -1.2 to -0.9] g·dL-1 ). Acid-base parameters were more stable with bal-GEL. No serious adverse drug reactions directly related to gelatin (i.e., anaphylactoid reaction, clotting disorders, and renal failure) were observed. CONCLUSION: Moderate doses up to 20 ml kg-1 of modified fluid gelatin were infused most frequently to improve hemodynamic stability in children undergoing major pediatric surgery. The acid-base balance was more stable when gelatin in a balanced electrolyte solution was used instead of saline. No serious adverse drug reactions associated with gelatin were observed.

[Case Series Report: Management of Anesthesia in Children Undergoing Complex Surgery of Tracheoesophageal Fistula after Ingestion of Button Batteries]. / Fallberichte: Kinder mit tracheoösophagealer Fistel nach Knopfbatterieningestion.

Button battery ingestions in children increased in recent years and may lead to life-threatening complications, especially if the battery is impacted in the esophagus. The pH close to the negative pole of the battery can rise in a very alkalotic range (pH > 10) leading to severe tissue damage. Therefore, in this case series report, the clinical courses of four children with button battery ingestion leading to tracheoesophageal fistulas are presented. The diagnosis and removal of the button battery was delayed in all cases. The surgical reconstruction of the trachea was performed in intravenous anesthesia and with extended monitoring. The intraoperative oxygenation was maintained using a combination of extracorporeal membrane oxygenation (ECMO) and mechanical ventilation via an endobronchial tube. To prevent these life-threatening complications, the awareness of the parents and child care providers should be raised, and the manufacturers should redesign their products to secure the battery compartment. In children with suspected battery ingestions, the immediate localization and removal of the battery (< 2 h) is of highest importance. Local administration of honey or sucralfate can be considered in ingestions < 12 h but should not delay an endoscopic removal.

Preparation of Dräger Atlan A350 and General Electric Healthcare Carestation 650 anesthesia workstations for malignant hyperthermia susceptible patients.

BACKGROUND: Patients at risk of malignant hyperthermia need trigger-free anesthesia. Therefore, anesthesia machines prepared for safe use in predisposed patients should be free of volatile anesthetics. The washout time depends on the composition of rubber and plastic in the anesthesia machine. Therefore, new anesthesia machines should be evaluated regarding the safe preparation for trigger-free anesthesia. This study investigates wash out procedures of volatile anesthetics for two new anesthetic workstations: Dräger Atlan A350 and General Electric Healthcare (GE) Carestation 650 and compare it with preparation using activated charcoal filters (ACF). METHODS: A Dräger Atlan and a Carestation 650 were contaminated with 4% sevoflurane for 90 min. The machines were decontaminated with method (M1): using ACF, method 2 (M2): a wash out method that included exchange of internal parts, breathing circuits and soda lime canister followed by ventilating a test lung using a preliminary protocol provided by Dräger or method 3 (M3): a universal wash out instruction of GE, method 4 (M4): M3 plus exchange of breathing system and bellows. Decontamination was followed by a simulated trigger-free ventilation. All experiments were repeated with 8% desflurane contaminated machines. Volatile anesthetics were detected with a closed gas loop high-resolution ion mobility spectrometer with gas chromatographic pre-separation attached to the bacterial filter of the breathing circuits. Primary outcome was time until < 5 ppm of volatile anesthetics and total preparation time. RESULTS: Time to < 5 ppm for the Atlan was 17 min (desflurane) and 50 min (sevoflurane), wash out continued for a total of 60 min according to protocol resulting in a total preparation time of 96-122 min. The Carestation needed 66 min (desflurane) and 24 min (sevoflurane) which could be abbreviated to 24 min (desflurane) if breathing system and bellows were changed. Total preparation time was 30-73 min. When using active charcoal filters time to < 5 ppm was 0 min for both machines, and total preparation time < 5 min. CONCLUSION: Both wash out protocols resulted in a significant reduction of trace gas concentrations. However, due to the complexity of the protocols and prolonged total preparation time, feasibility in clinical practice remains questionable. Especially when time is limited preparation of the anesthetic machines using ACF remain superior.

Quality-improvement project to reduce actual fasting times for fluids and solids before induction of anaesthesia.

BACKGROUND: Despite well-defined recommendations, prolonged fasting times for clear fluids and solids are still common before elective surgery in adults. Extended fasting times may lead to discomfort, thirst, hunger and physiological dysfunctions. Previous studies have shown that prolonged fasting times are frequently caused by patients being misinformed as well as inadequate implementation of the current guidelines by medical staff. This study aimed to explore how long elective surgery patients fast in a German secondary care hospital before and after the introduction of an educational note for patients and re-training for the medical staff. METHODS: A total of 1002 patients were enrolled in this prospective, non-randomised interventional study. According to the power calculation, in the first part of the study actual fasting times for clear fluids and solids were documented in 502 consecutive patients, verbally instructed as usual regarding the recommended fasting times for clear fluids (2 h) and solids (6 h). Subsequently, we implemented additionally to the verbal instruction a written educational note for the patients, including the recommended fasting times. Furthermore, the medical staff was re-trained regarding the fasting times using emails, newsletters and employee meetings. Thereafter, another 500 patients were included in the study. We hypothesised, that after these quality improvement procedures, actual fasting times for clear fluids and solids would be more accurate on time. RESULTS: Actual fasting times for clear fluids were in the median 11.3 (interquartile range 6.8-14.3; range 1.5-25.5) h pre-intervention, and were significantly reduced to 5.0 (3.0-7.2; 1.5-19.8) h after the intervention (median difference (95%CI) - 5.5 (- 6.0 to - 5.0) h). The actual fasting times for solids also decreased significantly, but only from 14.5 (12.1-17.2; 5.4-48.0) h to 14.0 (12.0-16.3; 5.4-32.0) h after the interventions (median difference (95%CI) - 0.52 (- 1.0 to - 0.07) h). CONCLUSIONS: The study showed considerably extended actual fasting times in elective adult surgical patients, which were significantly reduced by simple educational/training interventions. However, the actual fasting times still remained considerably longer than defined in recommended guidelines, meaning further process optimisations like obligatory fluid intake in the early morning are necessary to improve patient comfort and safety in future. TRIAL REGISTRATION: German registry of clinical studies (DRKS-ID: DRKS 00020530 , retrospectively registered).

Correlation of exhaled propofol with Narcotrend index and calculated propofol plasma levels in children undergoing surgery under total intravenous anesthesia - an observational study.

BACKGROUND: Exhaled propofol concentrations correlate with propofol concentrations in adult human blood and the brain tissue of rats, as well as with electroencephalography (EEG) based indices of anesthetic depth. The pharmacokinetics of propofol are however different in children compared to adults. The value of exhaled propofol measurements in pediatric anesthesia has not yet been investigated. Breathing system filters and breathing circuits can also interfere with the measurements. In this study, we investigated correlations between exhaled propofol (exP) concentrations and the Narkotrend Index (NI) as well as calculated propofol plasma concentrations. METHODS: A multi-capillary-column (MCC) combined with ion mobility spectrometry (IMS) was used to determine exP. Optimal positioning of breathing system filters (near-patient or patient-distant) and sample line (proximal or distal to filter) were investigated. Measurements were taken during induction (I), maintenance (M) and emergence (E) of children under total intravenous anesthesia (TIVA). Correlations between ExP concentrations and NI and predicted plasma propofol concentrations (using pediatric pharmacokinetic models Kataria and Paedfusor) were assessed using Pearson correlation and regression analysis. RESULTS: Near-patient positioning of breathing system filters led to continuously rising exP values when exP was measured proximal to the filters, and lower concentrations when exP was measured distal to the filters. The breathing system filters were therefore subsequently attached between the breathing system tubes and the inspiratory and expiratory limbs of the anesthetic machine. ExP concentrations significantly correlated with NI and propofol concentrations predicted by pharmacokinetic models during induction and maintenance of anesthesia. During emergence, exP significantly correlated with predicted propofol concentrations, but not with NI. CONCLUSION: In this study, we demonstrated that exP correlates with calculated propofol concentrations and NI during induction and maintenance in pediatric patients. However, the correlations are highly variable and there are substantial obstacles: Without patient proximal placement of filters, the breathing circuit tubing must be changed after each patient, and furthermore, during ventilation, a considerable additional loss of heat and moisture can occur. Adhesion of propofol to plastic parts (endotracheal tube, breathing circle) may especially be problematic during emergence. TRIAL REGISTRATION: The study was registered in the German registry of clinical studies (DRKS-ID:  DRKS00015795 ).

Prevention of postoperative bleeding after complex pediatric cardiac surgery by early administration of fibrinogen, prothrombin complex and platelets: a prospective observational study.

BACKGROUND: Postoperative bleeding is a major problem in children undergoing complex pediatric cardiac surgery. The primary aim of this prospective observational study was to evaluate the effect of an institutional approach consisting of early preventive fibrinogen, prothrombin complex and platelets administration on coagulation parameters and postoperative bleeding in children. The secondary aim was to study the rate of re-intervention and postoperative transfusion, the occurrence of thrombosis, length of mechanical ventilation, ICU stay and mortality. METHODS: In fifty children (age 0-6 years) with one or more predefined risk factors for bleeding after cardiopulmonary bypass (CPB), thrombelastography (TEG) and standard coagulation parameters were measured at baseline (T1), after CPB and reversal of heparin (T2), at sternal closure (T3) and after 12 h in the ICU (T4). Clinical bleeding was evaluated by the surgeon at T2 and T3 using a numeric rating scale (NRS, 0-10). RESULTS: After CPB and early administration of fibrinogen, prothrombin complex and platelets, the clinical bleeding evaluation score decreased from a mean value of 6.2 ± 1.9 (NRS) at T2 to a mean value of 2.1 ± 0.8 at T3 (NRS; P <  0.001). Reaction time (R), kinetic time (K), maximum amplitude (MA) and maximum amplitude of fibrinogen (MA-fib) improved significantly (P <  0.001 for all), and MA-fib correlated significantly with the clinical bleeding evaluation (r = 0.70, P <  0.001). The administered total amount of fibrinogen (mg kg- 1) correlated significantly with weight (r = - 0.42, P = 0.002), priming volume as percentage of estimated blood volume (r = 0.30, P = 0.034), minimum CPB temperature (r = - 0.30, P = 0.033) and the change in clinical bleeding evaluation from T2 to T3 (r = 0.71, P <  0.001). The incidence of postoperative bleeding (> 10% of estimated blood volume) was 8%. No child required a surgical re-intervention, and no cases of thrombosis were observed. Hospital mortality was 0%. CONCLUSION: In this observational study of children with an increased risk of bleeding after CPB, an early preventive therapy with fibrinogen, prothrombin complex and platelets guided by clinical bleeding evaluation and TEG reduced bleeding and improved TEG and standard coagulation parameters significantly, with no occurrence of thrombosis or need for re-operation. TRIAL REGISTRATION: German Clinical Trials Register DRKS00018109 (retrospectively registered 27th August 2019).

Impact of clear fluid fasting on pulmonary aspiration in children undergoing general anesthesia: Results of the German prospective multicenter observational (NiKs) study.

BACKGROUND: A preliminary national audit of real fasting times including 3324 children showed that the fasting times for clear fluids and light meals were frequently shorter than recommended in current guidelines, but the sample size was too small for subgroup analyses. AIMS: Therefore, the primary aim of this extended study with more participating centers and a larger sample size was to determine whether shortened fasting times for clear fluids or light meals have an impact on the incidence of regurgitation or pulmonary aspiration during general anesthesia in children. The secondary aim was to evaluate the impact of age, emergent status, ASA classification, induction method, airway management or surgical procedure. METHODS: After the Ethics Committee's approval, at least more than 10 000 children in total were planned to be enrolled for this analysis. Patient demographics, real fasting times, anesthetic and surgical procedures, and occurrence of target adverse events defined as regurgitation or pulmonary aspiration were documented using a standardized case report form. RESULTS: At fifteen pediatric centers, 12 093 children scheduled for surgery or interventional procedures were included between October 2018 and December 2019. Fasting times were shorter than recommended in current guidelines for large meals in 2.5%, for light meals in 22.4%, for formula milk in 5.3%, for breastmilk in 10.9%, and for clear fluids in 39.2%. Thirty-one cases (0.26%) of regurgitation, ten cases (0.08%) of suspected pulmonary aspiration, and four cases (0.03%) of confirmed pulmonary aspiration were reported, and all of them recovered quickly without any consequences. Fasting times for clear fluids shortened from 2 hours to 1 hour did not affect the incidence of adverse events (upper limit 95% CI 0.08%). The sample size of the cohort with fasting times for light meals shorter than 6 hours was too small for a subgroup analysis. An age between one and 3 years (odds ratio 2.7,95% CI 1.3 to 5.8%; P < .01) and emergent procedures (odds ratio 2.8,95% CI 1.4 to 5.7;P < .01) increased the incidence of adverse events, whereas ASA classification, induction method, or surgical procedure had no influence. The clear fluid fasting times were shortest under 6/4/0 as compared to 6/4/1 and 6/4/2 fasting regimens, all with an incidence of 0.3% for adverse events. CONCLUSION: This study shows that a clear fluid fasting time shortened from 2 hours to 1 hour does not affect the incidence of regurgitation or pulmonary aspiration, that an age between one and 3 years and emergent status increase the incidence of regurgitation or pulmonary aspiration, and that pulmonary aspiration followed by postoperative respiratory distress is rare and usually shows a quick recovery.

Systemic and regional cerebral perfusion in small infants undergoing minor lower abdominal surgery under awake caudal anaesthesia: An observational study.

BACKGROUND: Infants undergoing general anaesthesia have an increased risk of severe respiratory and cardiovascular critical events. Awake caudal anaesthesia is an alternative for small infants undergoing minor lower abdominal surgery. While clinical experience has shown stable intra-operative haemodynamic conditions, there are no studies evaluating systemic and regional cerebral perfusion during such a procedure. OBJECTIVES: The purpose of this study was to evaluate the effects of awake caudal anaesthesia on systemic and regional cerebral perfusion in small infants. DESIGN: A prospective observational cohort study. SETTING: Clinic of Anaesthesiology, University Children's Hospital, between November 2017 and June 2018. PATIENTS: Twenty small infants (postmenstrual age 36 to 54 weeks, weight 1800 to 5700 g) scheduled for lower abdominal surgery under awake caudal anaesthesia were enrolled in this study. INTERVENTION: Standard monitoring was expanded to include cardiac index using electrical velocimetry and regional cerebral oxygen saturation using near infrared spectroscopy. The caudal block was performed with 0.3% ropivacaine 1 ml kg Hypotension was defined as mean arterial blood pressure (BP) less than 35 mmHg and regional cerebral desaturation as regional cerebral oxygen saturation less than 80% of baseline. MAIN OUTCOMES: Mean arterial BP, cardiac index and regional cerebral oxygen saturation parameters under awake caudal anaesthesia. RESULTS: Mean arterial BP, cardiac index and regional cerebral oxygen saturation remained above the predefined lower limits. No episodes of hypotension or regional cerebral desaturation were observed. Operation time was 35 ±â€Š13 (range 20 to 71) min. The infants were discharged to the neonatal ward after the end of surgery, and milk was fed 22 ±â€Š15 (range 6 to 55) min thereafter. Five preterm infants experienced self-limiting episodes of apnoea intra-operatively. CONCLUSION: The current study shows that awake caudal anaesthesia does not impair systemic and regional cerebral perfusion in small infants. TRIAL REGISTRATION: German registry of clinical studies (DRKS-ID: 800015742).

Preparation of anaesthesia workstation for trigger-free anaesthesia: An observational laboratory study.

BACKGROUND: Trigger-free anaesthesia is required for patients who are susceptible to malignant hyperthermia. Therefore, all trace of volatile anaesthetics should be removed from anaesthetic machines before induction of anaesthesia. Because the washout procedure is time consuming, activated charcoal filters have been introduced, but never tested under minimal flow conditions. OBJECTIVE: To investigate performance of activated charcoal filters during long duration (24 h) simulated ventilation. DESIGN: A bench study. SETTING: A Primus anaesthesia machine (Dräger) was contaminated with either 4% sevoflurane or 8% desflurane by ventilating a test lung for 90 min. The machine was briefly flushed according to manufacturer instructions, activated charcoal filters were inserted and a test lung was ventilated in a 24 h test. Trace gas concentrations were measured using a closed gas loop high-resolution ion mobility spectrometer with gas chromatographic preseparation. During the experiment reduced fresh gas flows were tested. At the end of each experiment the activated charcoal filters were removed and the machine was set to standby for 10 min to test for residual contamination within the circuit. The activated charcoal filters were reconnected into the circuit to test their ability to continue removing volatile anaesthetics (functional test) from the gas. Control experiments were conducted without activated charcoal filters. MAIN OUTCOME MEASURES: Absolute concentrations of desflurane and sevoflurane. RESULTS: The concentration of volatile anaesthetics dropped to less than 5 ppm (parts per million) following insertion of activated charcoal filters. In the desflurane experiments at least 1 l min FGF was needed to keep the concentration below an acceptable level (<5 ppm): 0.5 l min fresh gas flow was required in sevoflurane experiments. While activated charcoal filters in the sevoflurane tests passed the functional test after 24 h, activated charcoal filters in the desflurane tests failed. CONCLUSION: Activated charcoal filters meet the requirements for trigger-free low flow (1 l min) ventilation over 24 h. Minimal flow (0.5 l min) ventilation may be possible for sevoflurane contaminated machines.

Low anaesthetic waste gas concentrations in postanaesthesia care unit: A prospective observational study.

BACKGROUND: Volatile anaesthetics are a potential hazard during occupational exposure, pregnancy or in individuals with existing disposition to malignant hyperthermia. Anaesthetic waste gas concentration in postanaesthesia care units (PACU) has rarely been investigated. OBJECTIVE(S): The current study aims to assess concentrations of volatile anaesthetics in relation to room size, number of patients and ventilator settings in different PACUs. DESIGN: A prospective observational study. SETTING: Two different PACUs of the Hannover Medical School (Hannover, Germany) were evaluated in this study. The rooms differed in dimensions, patient numbers and room ventilation settings. PATIENTS: During the observation period, sevoflurane anaesthesia was performed in 65 of 140 patients monitored in postanaesthesia unit one and in 42 of 70 patients monitored in postanaesthesia unit two. MAIN OUTCOME MEASURES: Absolute trace gas room concentrations of sevoflurane measured with a compact, closed gas loop high-resolution ion mobility spectrometer. RESULTS: Traces of sevoflurane could be detected in 805 out of 970 samples. Maximum concentrations were 0.96 ±â€Š0.20 ppm in postanaesthesia unit one, 0.82 ±â€Š0.07 ppm in postanaesthesia unit two. Median concentration was 0.12 (0.34) ppm in postanaesthesia unit one and 0.11 (0.28) ppm in postanaesthesia unit two. CONCLUSION: Low trace amounts of sevoflurane were detected in both PACUs equipped with controlled air exchange systems. Occupational exposure limits were not exceeded.

Effect of age on Narcotrend Index monitoring during sevoflurane anesthesia in children below 2 years of age.

BACKGROUND: In older children, different electroencephalogram-based algorithms for measuring depth of anesthesia displayed a similar performance as in adults, but in infants they have not displayed the same reliability so far. According to the individual developmental state, the Narcotrend distinguishes "differentiated" electroencephalograms, which can be classified using the full Narcotrend Index scale, from "undifferentiated" electroencephalograms, which are classified using a scale with fewer stages. OBJECTIVE: The objective of this prospective clinical observational study was to assess the feasibility and performance of the Narcotrend monitor in children <2 years within a clinical setting. METHODS: Sixty-one children aged 0-24 months undergoing general anesthesia with sevoflurane and remifentanil for elective pediatric surgery were studied. We investigated the percentage of differentiated electroencephalograms and the correlation between multiples of minimal alveolar sevoflurane concentration and the Narcotrend Index according to age groups. Prediction probability was used to evaluate the performance of the Narcotrend Index for differentiation between consciousness and unconsciousness and between different sevoflurane concentrations. RESULTS: The percentage of differentiated electroencephalograms increased with increasing age (0-3 months: 23.8%, 4-5 months: 87.5%, 6-11 months: 92.3%, 12-24 months: 100%). The overall prediction probability of Narcotrend Index was 1.0 (SE 0.05) for differentiation between awake and loss of consciousness and 1.0 (SE 0.01) for differentiation between anesthetized and return of consciousness. Spearman correlation analysis revealed a significant negative correlation between sevoflurane concentration and the Narcotrend Index (r = -0.78, P < .0001, 95%CI: -0.81 to -0.74). Overall prediction probability of Narcotrend Index to sevoflurane concentration was 0.8 (95%CI: 0.78-0.82). CONCLUSION: The Narcotrend monitor indicated a Narcotrend Index in most infants and young children starting from 4 months with significant correlation to and acceptable prediction probability for minimal alveolar sevoflurane concentration.

Impact of temperature on the Narcotrend Index during hypothermic cardiopulmonary bypass in children with sevoflurane anesthesia.

BACKGROUND: During cardiopulmonary bypass (CPB) in children, anesthesia maintained by sevoflurane administered via the oxygenator is increasingly common. Anesthetic uptake and requirement may be influenced by the non-physiological conditions during hypothermic CPB. Narcotrend-processed EEG monitoring may, therefore, be useful to guide the administration of sevoflurane during this phase. OBJECTIVE: The objective of this prospective, clinical, observational study was to assess the correlation between body temperature, Narcotrend Index (NI) and administered sevoflurane in children during CPB. METHODS: Forty-four children aged 0 to 10 years undergoing hypothermic cardiac surgery were studied. On bypass, anesthesia was maintained with sevoflurane administered via the oxygenator of the heart-lung machine. Nasopharyngeal temperature, NI and minimum alveolar concentration (MAC) of sevoflurane were recorded in intervals of 10 minutes. Expiratory gas was sampled from the oxygenator's sole expiratory port via a separate connecting line and the MAC was measured by the agent analyzer of the anesthesia machine. RESULTS: Raw (r = 0.74) and corrected (r = 0.73) r-values show that narcosis depth (as indicated by NI) can primarily be explained by the interaction of MAC and temperature. The analysis of variance (without the interaction term) confirms the significant and independent association of both factors, MAC (p<0.004, 95%CI: 0.19 to 0.46) and temperature (p<0.0001, 95%CI: 0.68 to 0.78), with the NI. During hypothermia, sevoflurane had been reduced significantly (r = 0.41, p<0.0001, 95%CI: 0.33 to 0.48). CONCLUSION: Perfusionists and anesthetists should be aware of the results of processed electroencephalograph (EEG) monitoring during CPB. Sevoflurane requirements differ inter-individually; they may decrease during cooling and increase during rewarming. Therefore, it seems reasonable to include the results of processed EEG monitoring when administering sevoflurane during CPB in children, but further studies are necessary to confirm this thesis.

[Perioperative Intravenous Fluid Therapy in Children]. / Perioperative Infusionstherapie bei Kindern ­ die neue S1-Leitlinie.

The objective of this consensus-based S1 Guideline for perioperative fluid therapy in children is to maintain or re-establish the child's homeostasis. Therefore, the perioperative fasting times should be as short as possible to prevent patient discomfort, dehydration, and ketoacidosis. For the intraoperative background infusion a physiologically composed balanced isotonic electrolyte solution (BS) with 1 - 2.5% glucose is recommended to maintain normal glucose concentrations and to avoid hyponatremia, hyperchloremia, and lipolysis. Additional BS without glucose can be used in patients with circulatory instability until the desired effect is achieved. The additional use of colloids is recommended to recover normovolemia and to avoid fluid overload when crystalloids alone are not sufficient and blood products are not indicated. Monitoring should be extended in cases with major surgery.

Optimization of initial propofol bolus dose for EEG Narcotrend Index-guided transition from sevoflurane induction to intravenous anesthesia in children.

BACKGROUND: Sevoflurane induction followed by intravenous anesthesia is a widely used technique to combine the benefits of an easier and less traumatic venipuncture after sevoflurane inhalation with a recovery with less agitation, nausea, and vomiting after total intravenous anesthesia (TIVA). Combination of two different anesthetics may lead to unwanted burst suppression in the electroencephalogram (EEG) during the transition phase. OBJECTIVE: The objective of this prospective clinical observational study was to identify the optimal initial propofol bolus dose for a smooth transition from sevoflurane induction to TIVA using the EEG Narcotrend Index (NI). METHODS: Fifty children aged 1-8 years scheduled for elective pediatric surgery were studied. After sevoflurane induction and establishing of an intravenous access, a propofol bolus dose range 0-5 mg·kg-1 was administered at the attending anesthetist's discretion to maintain a NI between 20 and 64, and sevoflurane was stopped. Anesthesia was continued as TIVA with a propofol infusion dose of 15 mg·kg-1 ·h-1 for the first 15 min, followed by stepwise reduction according to McFarlan's pediatric infusion regime, and remifentanil 0.25 µg·kg-1 ·min-1 . Endtidal concentration of sevoflurane, NI, and hemodynamic data were recorded during the whole study period using a standardized case report form. Propofol plasma concentrations were calculated using the paedfusor dataset and a TIVA simulation program. RESULTS: Median endtidal concentration of sevoflurane at the time of administration of the propofol bolus was 5.1 [IQR 4.7-5.9] Vol%. The median propofol bolus dose was 1.2 [IQR 0.9-2.5] mg·kg-1 and median NI thereafter was 33 [IQR 23-40]. Nine children presented with a NI 13-20 and three children with burst suppression in the EEG (NI 0-12); all of them received an initial propofol bolus dose >2 mg·kg-1 . Regression equation demonstrated that NI 20-64 was achieved with a 95% probability when using a propofol bolus dose of 1 mg·kg-1 after sevoflurane induction. Decrease in mean arterial blood pressure correlated significantly with propofol bolus dose (P = 0.038). After 25 min of TIVA, children younger than 2 years had a higher NI (median difference 14.0, 95%CI: 6.0-20.0, P = 0.001), higher deviations from the expected Narcotend Index (median difference 4.1, 95%CI: 3.9-4.2, P < 0.001) and lower calculated propofol plasma concentrations (median difference 0.2 µg·ml-1 , 95% CI: 0.1-0.3 µg·ml-1 , P < 0.001) than older children. CONCLUSION: After sevoflurane induction, a reduced propofol bolus dose of 1 mg·kg-1 followed by TIVA according to McFarlan's regime resulted in a NI within the recommended range in children aged 1-8 years. During the course of TIVA, children younger than 2 years displayed higher NI values and more pronounced interindividual variation. Processed EEG monitoring is recommended to find adequate individual age-dependent doses.

Metamizole for Postoperative Pain Therapy in Infants Younger than 1 Year.

Background Due to possible serious adverse drug reactions (ADRs), the use of metamizole for postoperative pain therapy in infants is a subject of debate. Safety studies with large sample sizes are missing. Aim This prospective multicenter observational study was conducted to evaluate the use of metamizole in infants younger than 1 year undergoing surgery with a particular focus on possible serious ADRs (e.g., hemodynamic, anaphylactic or respiratory reactions, and agranulocytosis). Methods Infants aged up to 1 year (American Society of Anesthesiologists [ASA] I-III) receiving a single dose of metamizole for postoperative pain therapy were enrolled. Patient demographics, main and secondary diagnosis, surgical procedures performed, metamizole dose, hemodynamic data, use of other analgesics and regional blocks, results of pain measurement, and incidence of ADRs were documented using a standardized case report form. Results A total of 316 infants observed at five pediatric centers were included for analysis (age 4.4 ± 3.7 [0.06-12] months). Mean metamizole dose was 17.8 ± 3.1 (9.2-29.8) mg·kg-1. Mean arterial pressure (MAP) remained stable during metamizole infusion (MAP before infusion 45 ± 9.5 [25-95] and after infusion 45 ± 9.2 [25-99] mm Hg). Erythema was observed in one patient (ADRs total: 0.3%, 95% confidence interval: 0.27-0.32). No respiratory adverse events directly related to the metamizole administration and no clinical signs of agranulocytosis were reported. Conclusion Single intravenous doses of metamizole used for prevention or treatment of postoperative pain were safe in more than 300 infants younger than 1 year. The statistical probability of serious ADRs (e.g., hemodynamic, anaphylactic or respiratory reactions) was lower than 1%. The sample size and follow-up were not sufficient to detect agranulocytosis.

Perioperative intravenous fluid therapy in children: guidelines from the Association of the Scientific Medical Societies in Germany.

This consensus- based S1 Guideline for perioperative infusion therapy in children is focused on safety and efficacy. The objective is to maintain or re-establish the child's normal physiological state (normovolemia, normal tissue perfusion, normal metabolic function, normal acid- base- electrolyte status). Therefore, the perioperative fasting times should be as short as possible to prevent patient discomfort, dehydration, and ketoacidosis. A physiologically composed balanced isotonic electrolyte solution (BS) with 1-2.5% glucose is recommended for the intraoperative background infusion to maintain normal glucose concentrations and to avoid hyponatremia, hyperchloremia, and lipolysis. Additional BS without glucose can be used in patients with circulatory instability until the desired effect is achieved. The additional use of colloids (albumin, gelatin, hydroxyethyl starch) is recommended to recover normovolemia and to avoid fluid overload when crystalloids alone are not sufficient and blood products are not indicated. Monitoring should be extended in cases with major surgery, and autotransfusion maneuvers should be performed to assess fluid responsiveness.