Effects of hypothermia and hypothermia combined with hypocapnia on cerebral tissue oxygenation in piglets.

BACKGROUND: Hypothermia and its combination with hypocapnia are frequently associated with anesthesia. AIMS: The goal was to investigate the effects of hypothermia and hypothermia combined with hypocapnia (hypothermia-hypocapnia) on cerebral tissue oxygenation in anesthetized piglets. METHODS: Twenty anesthetized piglets were randomly allocated to hypothermia (n = 10) or hypothermia-hypocapnia (n = 10). Cerebral monitoring comprised a tissue oxygen partial pressure (PtO2 ), a laser Doppler probe, and a near-infrared spectroscopy sensor, measuring regional oxygen saturation (rSO2 ). After baseline recordings, hypothermia (35.5-36.0°C) with or without hypocapnia (target PaCO2 : 28-30 mm Hg) was induced. Once treatment goals were achieved (Tr0), they were maintained for 30 minutes (Tr30). RESULTS: No changes in PtO2 but a significant increase in rSO2 (Tr0 (mean difference 8.9[95% CI for difference3.99 to 13.81], P < .001); Tr30 (10.8[6.20 to 15.40], P < .001)) were detected during hypothermia. With hypothermia-hypocapnia, a decrease in PtO2 (Tr0 (-3.2[-6.01 to -0.39], P = .021; Tr30 (-3.3[-5.8 to -0.80], P = .006)) and no significant changes in rSO2 occurred. Cerebral blood flow decreased significantly from baseline to Tr0 independently of treatment (-0.89[-0.18 to -0.002], P = .042), but this was more consistently observed with hypothermia-hypocapnia. CONCLUSIONS: The hypothermia-induced reduction in oxygen delivery was compensated by lowered metabolic demand. However, hypothermia was not able to compensate for an additional reduction in oxygen delivery caused by simultaneous hypocapnia. This resulted in a PtO2 drop, which was not reflected by a downshift in rSO2 .

Hypotension and Hypocapnia During General Anesthesia in Piglets: Study of S100b as an Acute Biomarker for Cerebral Tissue Injury.

BACKGROUND: Hypotension and/or hypocapnia might increase general anesthesia (GA)-related neuromorbidity in infants, but safe levels of perioperative blood pressure are poorly defined. Serum protein S100b has been used as screening, monitoring, and prediction tool in the management of patients with traumatic brain injury. Using an animal model, we investigated serum S100b as an acute biomarker of cerebral hypoperfusion and cerebral cell dysfunction during hypotension, hypocapnia, or combined hypotension/hypocapnia during GA. METHODS: Fifty-seven sevoflurane-midazolam anesthetized piglets aged 4 to 6 weeks were randomly allocated to control (n=9), hypotension (n=18), hypocapnia (n=20), or combined hypotension and hypocapnia (n=10). Hypotension (target mean arterial blood pressure: 35 to 38 or 27 to 30 mm Hg) was induced by blood withdrawal and nitroprusside infusion, and hypocapnia by hyperventilation (target PaCO2: 28 to 30 and 23 to 25 mm Hg). Serum S100b and albumin were measured at baseline, before and 60 minutes after the interventions, and following 60-minute recovery. RESULTS: Serum S100b concentrations decreased over time (P=0.001), but there was no difference in S100b between control piglets and those exposed to hypotension, hypocapnea, or a combination of the both (P=0.105). Albumin decreased in all 4 groups (P=0.001). CONCLUSION: S100b did not increase following 60 minutes of systemic hypotension and/or hypocapnia during GA in piglets. In this setting, the use of S100b as a biomarker of cerebral cell tissue dysfunction cannot be supported.

Effects of moderate and severe hypocapnia on intracerebral perfusion and brain tissue oxygenation in piglets.

BACKGROUND: Hypocapnia is a common alteration during anesthesia in neonates. AIM: To investigate the effects of hypocapnia and hypocapnia combined with hypotension (HCT) on cerebral perfusion and tissue oxygenation in anesthetized piglets. METHOD: Thirty anesthetized piglets were randomly allocated to groups: moderate hypocapnia (mHC), severe hypocapnia (sHC), and HCT. Cerebral monitoring comprised a tissue oxygen partial pressure and a laser Doppler probe inserted into the brain tissue as well as a near-infrared spectroscopy (NIRS) sensor placed on the skin, measuring regional oxygen saturation. Hypocapnia was induced by hyperventilation (target PaCO2 mHC: 3.7-4; sHC: 3.1-3.3 kPa) and hypotension by blood withdrawal and nitroprusside infusion (mean blood pressure: 35-38 mm Hg). Data were analyzed at baseline, during (Tr20, Tr40, Tr60) and after (Post20, Post40, Post60) treatment. RESULTS: Compared to baseline, tissue oxygen partial pressure decreased significantly and equally during all treatments (mean [SD] at baseline: mHC 35.7 [32.45]; sHC: 28.1 [20.24]; HCT 25.4 [10.3] and at Tr60: mHC: 29.9 [27.36]; sHC: 22.2 [18.37]; HCT: 18.4 [9.5] mm Hg). Decreased laser Doppler flow was detected with all treatments at Tr20 (mHC: 0.9 [0.18]; sHC: 0.88 [0.15]; HCT: 0.97 [0.13] proportion from baseline). Independently of group, regional oxygen saturation varied only after reverting and not during treatment. Blood lactate, pH, HCO3- , and PaO2 increased during treatment with no differences between groups. CONCLUSION: This animal model revealed reduced cerebral blood flow and brain tissue oxygenation during hypocapnia without detectable changes in regional oxygen saturation as measured by NIRS. Changes occurred as early as during moderate hypocapnia.

Effects of hypotension and/or hypocapnia during sevoflurane anesthesia on perfusion and metabolites in the developing brain of piglets-a blinded randomized study.

BACKGROUND: Hypotension (HT) and/or hypocapnia (HC) are frequent complications occurring during pediatric anesthesia and may cause cerebral injury in the developing brain. AIM: The aim of this study is to investigate the effects of HT and/or HC on perfusion and metabolism in the developing brain. METHODS: Twenty-eight piglets were randomly allocated to four groups: control (C), HT, HC, and hypotension and hyocapnia (HTC). Anesthesia was induced and maintained using sevoflurane. Fentanyl was added for instrumentation. Piglets were fully monitored and their lungs were artificially ventilated. Before treatment, conventional magnetic resonance imaging (MRI), dynamic susceptibility-contrast-enhanced T2*-weighted MRI (DSC-MRI), and single voxel proton MR spectroscopy ((1) H MRS) were performed. Hypotension (mean arterial blood pressure: 30 ± 3 mmHg) was induced by blood withdrawal and nitroprusside infusion, and hyperventilation was used to induce HC (PaCO2 : 2.7-3.3 kPa). (1) H MRS and DSC-MRI were repeated immediately once treatment goals were achieved and 120 min later. Radiologists were blinded to the groups. DSCI-MRI and (1) H MRS analyses were performed in the thalamus, occipital and parietal lobe, hippocampus, and watershed areas. RESULTS: In comparison to C, mean time to peak (TTP) increased with HTC in all brain areas as assessed with DSC-MRI (n = 26). Using (1) H MRS, a significant decrease in N-acetyl aspartate, choline, and myoinositol, as well as an increase in glutamine-glutamate complex (Glx) were detected independent of group. Compared to C, changes were more pronounced for Glx (due to an increase in glutamate) and myoinositol with HTC, for N-acetyl aspartate with HT, and for Glx with HC. No lactate signal was present. CONCLUSIONS: The combination of HT and HC during sevoflurane anesthesia resulted in alteration of cerebral perfusion with signs of neuronal dysfunction and early neuronal ischemia. HT and HC alone also resulted in signs of metabolic disturbances despite the absence of detectable cerebral perfusion alterations.

Economic aspects of intraoperative coagulation management targeting higher fibrinogen concentrations during major craniosynostosis surgery.

BACKGROUND: Results of a previously published study demonstrated a significant decrease in transfusion requirements and calculated blood loss for pediatric major craniosynostosis surgery, if a ROTEM(®) FIBTEM trigger of <13 mm (early substitution group) was applied as compared to a trigger of <8 mm (conventional group). The aim of this study was a posthoc analysis of the costs for this coagulation management. METHODS: The total volume as well as the number of units or bags for all transfused blood products and coagulation factors were recorded for each case. The number of laboratory and point-of-care coagulation tests was also analyzed. Total blood product costs were calculated according to the local prices per unit. RESULTS: The total cost for all transfused/administered blood products/coagulation factors per patient was a median of 1023EUR (IQR 850EUR-1058EUR) in the early substitution group as compared to a median of 910EUR (IQR 719EUR-1351EUR) in the conventional group (P = 0.81). No difference in the number of coagulation tests performed was observed. CONCLUSION: In this study, the use of a higher fibrinogen trigger was not linked to a significant increase in total costs for transfused blood products and coagulation factors, and may offer an economically equivalent approach to coagulation management.

Impact of incorrect filling of citrate blood sampling tubes on thromboelastometry.

BACKGROUND: ROTEM(®) test results can be affected by the citrate to blood ratio in the tested sample. Overfilling or underfilling specimen tubes can change this ratio. OBJECTIVES: The aim of this study was to determine the impact of under- and overfilling citrate test tubes on ROTEM(®) EXTEM measurements. RESULTS: Overall repeated measures ANOVA demonstrated significant differences of CT (p = 0.004), CFT (p = 0.005), A5 (p = 0.001), A10 (p <0.001), and MCF (p < 0.001). Pairwise comparison revealed that underfilling significantly altered the results of those parameters reflecting functional clot firmness (A5, A10, and MCF), while overfilling led to a prolongation of the CT results only. No differences were observed for alpha angle and maximum lysis. CONCLUSION: Both underfilling and overfilling specimen tubes have significant influence on the results of the ROTEM(®) EXTEM test, although the small observed bias is likely of limited clinical relevance. However, it seems prudent to limit the maximum allowed difference in filling to less than ± 10%. All ROTEM(®) operators should be aware of this pre-analytical variable.

Comparison of conventional ROTEM® cups and pins to the ROTEM® cup and pin mini measuring cells (MiniCup).

BACKGROUND: Thromboelastometry (ROTEM®) is a well-established measurement to guide perioperative coagulation management. Recently, an enhancement for low volume specimens using cup and pin mini measuring cells (MiniCup) was invented for scientific non-clinical use. The MiniCup measuring cells allow testing with half of the blood volume required to run a test as compared to the conventional ROTEM® cup and pin (150 µL vs. 300 µL per assay). OBJECTIVES: The aim of this prospective study was to compare ROTEM® results using conventional cups and pins to the results of the MiniCup measuring cells. METHODS: Blood samples drawn during major pediatric surgery were analyzed using the conventional ROTEM® and the MiniCup system to compare parameters from the EXTEM, INTEM and FIBTEM assays. RESULTS: Citrated blood samples (n = 120) from 70 pediatric patients were analyzed. Results of the MiniCup cells were considerably different than the conventional ROTEM® cups and pins measurements. The MiniCup results show less clot firmness and demonstrate higher variability in the parameters reflecting the kinetics of clot building. CONCLUSION: The MiniCup measuring cells may offer advantages in pediatric care or research facilities, but specific reference ranges need to be established first, and adequate reproducibility must be determined by further studies before clinical use can be recommended.

Impact of catecholamines in cardiac arrest due to acute asphyxia--a study in piglets.

BACKGROUND: Early intravenous epinephrine administration may help to achieve return of spontaneous circulation in cardiac arrest (CA). However, venous access can be challenging in small children. This study investigates the effect of intravenous and intramuscular epinephrine in treatment of asphyxial CA. METHODS: Twenty-eight, 2-5-weeks-old, anesthetized piglets were asphyxiated by ventilation withdrawal. CA was untreated for 8 min, followed by 2 min of basic life support. Following this, epinephrine iv (10 µg·kg(-1) , group IV), epinephrine im (100 µg·kg(-1) , group IM), or normal saline (group NS) were administered. Further doses of epinephrine were given in group IV every 4 min, in group IM after 10 min if required. After twenty-two minutes of CA, iv epinephrine was given to all animals still in CA. Outcome measures were survival and epinephrine plasma concentrations. RESULTS: Ten animals regained spontaneous circulation after 2 min of basic life support. Therefore, no drug treatment was administered (drop out). Resuscitation was effective in 2 pigs of group IM (n = 6), in 6 of group NS (n = 8) and in all of group IV (n = 4). Nonsurvivors had higher epinephrine (P < 0.01) and norepinephrine (P < 0.01) plasma concentrations prior to start of resuscitation. Median increase in epinephrine plasma concentration from T0 to T5 was 138, 134, and 29 nm in group IV, IM, and NS, respectively. CONCLUSIONS: Intravenous and intramuscular administered epinephrine led to similar increase in plasma concentrations during resuscitation of asphyxial CA without hemodynamic or survival benefit. High endogenous epinephrine and norepinephrine plasma concentrations were negative predictors for survival.

Improvements in patient blood management for pediatric craniosynostosis surgery using a ROTEM(®) -assisted strategy - feasibility and costs.

BACKGROUND: Moderate to severe intraoperative bleeding and the presence of acquired coagulopathy remain serious problems in the management of major pediatric craniosynostosis surgery. After implementation of a ROTEM(®) -assisted patient blood management (PBM) strategy, using primarily purified coagulation factor concentrates, feasibility and costs of this new regimen were analyzed. METHODS: Retrospective analysis of all consecutive children who underwent primary elective major craniofacial surgery for craniosynostosis repair was carried out at the Children's University Hospital, Zurich, between 2007 and 2013. Laboratory workup and transfusion requirements were compared. RESULTS: A total of 47 children (36 in the historic group and 11 after implementation of PBM) were analyzed. Although all patients in this study needed transfusion of red blood cell concentrates, there was a total avoidance of perioperative transfusion of fresh frozen plasma and a reduction in transfused platelets (one of nine children vs nine of 36 children in the historic group) after implementation of the PBM strategy. Based on a predefined ROTEM(®) threshold in the PBM group (FibTEM MCF <8 mm), administration of fibrinogen concentrate was necessary in all of these children. The mean total costs per patient consisting of transfused allogeneic blood products and coagulation factor concentrates were reduced by 17.1% after implementation of PBM (1071.82 EUR per patient before vs 888.93 EUR after implementation). CONCLUSIONS: The implementation of a ROTEM(®) -assisted PBM is feasible and is associated with a considerable reduction in intraoperative transfusion requirements and thereby a decrease in transfusion-related direct costs.

Intravenous versus intramuscular epinephrine administration during cardiopulmonary resuscitation - a pilot study in piglets.

BACKGROUND: Early epinephrine administration in cardiac arrest seems to be advantageous to achieve return of spontaneous circulation (ROSC). Because intravenous (i.v.) or intraosseous access is not always immediately available, this study compares efficacy of early intramuscular (i.m.) epinephrine administration with early and delayed i.v. epinephrine injection in an animal cardiac arrest model. METHODS: Piglets anesthetized with sevoflurane were intoxicated by an i.v. ropivacaine infusion until circulatory arrest. After 1 min basic life support (chest compression and ventilation), epinephrine i.v. (10 µg·kg(-1), group IV) or epinephrine i.m. (100 µg·kg(-1), group IM) or normal saline (group NS) was applied. Further doses of epinephrine were given in group IV every 4 min and in group IM after 10 min if required. Twenty-one minutes after circulatory arrest, i.v. epinephrine - as necessary - was given to all animals. Thus, group NS represents late epinephrine administration. Outcomes were survival and time to ROSC. RESULTS: Twenty-four pigs aged 19.5 (median, interquartile range 16-22) days, weighing 5.4 (5.0-5.7) kg were investigated. Total amount of ropivacaine administered was 8.9 (8.1-10.1) mg·kg(-1). Cardiac rhythm before starting CPR was pulseless electric activity and asystole in 15 and 9 pigs, respectively. Eight, seven, and four pigs survived in group IV, IM, and NS. Focusing on surviving animals, time to ROSC was 2, 4 and 19.5 min in group IV, IM, and NS. CONCLUSIONS: Early i.m. epinephrine provided similar survival compared with early i.v. epinephrine and was superior to delayed epinephrine administration in resuscitation of ropivacaine-induced cardiac arrest in piglets.

Endoscopic airway findings in children with or without prior endotracheal intubation.

BACKGROUND: Airway alterations found after endotracheal intubation are usually associated with mechanical trauma from the tube. However, no studies are available concerning alterations in airways that have never been intubated before. It was the aim of the study to compare endoscopic findings in the larynx and trachea of children who had undergone prior endotracheal intubation with findings in children who had not been intubated before. METHODS: In 1021 children aged from 0 to 6 years, rigid endoscopies were performed before planned elective endotracheal intubation. The anonymized endoscopy videos were reviewed and graded by five international airway experts. Data was compared between the two groups using the chi-square test (P ≤ 0.05). RESULTS: Endoscopic records of 971 children (473 with prior intubation; 498 without prior airway intubation) were included in the final calculations. Most patients (93.7%) with prior intubation had been intubated with a cuffed tube. The number of intubations ranged from 1 to 27. The median interval between intubation and endoscopy was 0.53 years (0.003-5.57 years). Abnormal findings were observed in 31.7% and 26.8% of patients with and without prior intubation, respectively (P = 0.063). Glottic granulomas were significantly more common after intubation (3.6% vs 1.4%; P = 0.028). The incidence of other abnormal findings was similar in both groups. CONCLUSION: Endoscopic airway alterations can be observed in about one-quarter of children presenting for routine surgery without prior intubation. Except for glottic granulomas, the abnormalities are found with similar frequency in patients with and without prior intubation. No relevant airway damage from short-term endotracheal intubation was found.

Effect of rapid fluid resuscitation using crystalloids or colloids on hemostasis in piglets.

BACKGROUND AND OBJECTIVES: Impairment of blood coagulation is one of the main side effects of volume replacement, particularly if artificial colloids such as hydroxyethyl starch (HES) and gelatine preparations are used. This animal study aimed to evaluate the effect of a single fast intravenous crystalloid or colloid fluid bolus on blood coagulation as measured by rotation thromboelastometry (ROTEM). METHODS: Thirty-two anesthetized piglets were infused with a rapid 20 ml·kg(-1) fluid bolus of either normal saline (NS), 4% gelatine, 5% albumin or 6% HES 130/0.4 (n = 8 per group) over a period of 2 min. Hemostasis was assessed by ROTEM before and 1 min after fluid administration. Within-group differences were analyzed by Wilcoxon test, and additionally overall Kruskal-Wallis test followed by posthoc Mann-Whitney U-test were applied to detect differences between groups. RESULTS: All fluids caused a significant weakening of clot strength within groups. HES and gelatine showed a significantly stronger impairment of clot growth and maximum clot firmness as compared with albumin and normal saline. Impairment of fibrin polymerization was more pronounced following HES as compared with all other fluids. CONCLUSION: After moderate but very fast volume loading, HES and gelatine impair blood coagulation to a larger extent as compared with albumin or normal saline, while no significant differences were observed between both artificial colloids.

Effect of Lanz pressure regulating valve on self-sealing mechanism and air leakage across the tracheal tube cuffs in a benchtop model.

BACKGROUND: The aim of the present study was to investigate the effect of the Lanz system on air sealing by self-inflation in high volume-low pressure (HVLP) tube cuffs. METHODS: In vitro tracheal air sealing was studied in HVLP tracheal tube cuffs (internal diameter [ID] 8.0 mm) made from polyurethane ([PU] Seal Guard tracheal tube, Covidien, Athlone, Ireland) and from polyvinylchloride ([PVC] HiLo tracheal tube, Covidien) with and without Lanz pressure regulating valve. Tube cuffs were placed in a vertical 22 mm ID artificial trachea and inflated to 5, 10, 15, 20, 25, or 30 cm H2O cuff pressures. Pressure control ventilation with peak inspiratory pressures (PIPs) of 20 or 25 cm H2O was applied and air leakage was assessed spirometrically as the ratio of expiratory to inspiratory tidal volumes. Nonparametric Mann-Whitney test was applied to compare the air leakage with and without Lanz system for both cuff types at each cuff pressure and PIP (P < .05). RESULTS: The PVC tube cuffs with Lanz system resulted in significant air leakage at both 20 and 25 cm H2O PIP as compared to those without the Lanz system, especially at cuff pressures lower than the preset PIP (P < .05). Although PU tube cuffs with Lanz system showed reduced air sealing when compared with cuffs without Lanz, the difference was not statistically significant. CONCLUSION: Cuff pressure compensation with the Lanz system during cyclic respiratory pressure changes interferes with the self-sealing mechanism in HVLP tube cuffs at cuff pressures lower than PIP level. This results in larger air leak across tube cuffs particularly in tube cuffs made from PVC.

Electrocardiographic and blood pressure alterations caused by intravenous injection of ropivacaine - a study in piglets.

OBJECTIVES: Objective signs to detect inadvertent intravascular injection of local anesthetics are essential in the anesthetized pediatric patient. For early detection of intravenous bupivacaine administration, it was shown that an epinephrine containing test dose reliably provoked T-wave alterations, changes in heart rate (HR) and blood pressure, whereas intravenous injection of plain bupivacaine could not be detected until high doses were applied. This study investigates electrocardiographic and hemodynamic alterations caused by intravenous ropivacaine. METHODS: Twenty-four piglets, anesthetized with sevoflurane, were randomized into two groups: Group R received as test dose plain ropivacaine 0.2% and group RE, ropivacaine 0.2% + epinephrine 5 µg·ml(-1) . Under stable conditions, 0.2 ml kg(-1) of the test solution was intravenously injected. Twenty minutes later, 0.4 ml kg(-1) was applied. A positive effect was defined as HR increase ≥ 10 bpm, increase in mean arterial pressure (MAP) ≥ 15 mmHg, T-wave increase ≥ 25% baseline. In another setting ropivacaine was intravenously infused until cardiac arrest. RESULTS: After injection of 0.2 or 0.4 ml kg(-1) test solution, a positive increase in HR and MAP was found in 0% of group R and in 100% of group RE. An increase in T-wave ≥ 25% was found in 42% of group R and in 100% of group RE. During intoxication, T-elevation was seen in 83%. CONCLUSIONS: An epinephrine containing test dose ropivacaine reliably provoked T-wave elevations and increases in HR and MAP. A small dose plain ropivacaine caused T-elevations in a remarkable percentage, whereas higher, quite toxic doses provoked T-elevations in most of the pigs.

Correlation of activated clotting times and standard laboratory coagulation tests in paediatric non-cardiac surgery.

The activated clotting time (ACT) was invented as a whole blood test to detect coagulopathy, but nowadays is almost exclusively used to guide heparin anticoagulation. Although the ACT provides a fairly reliable and fast bedside test of the coagulation status, only a few studies have focused on its use to monitor pre- or intraoperative coagulation status as an early marker of impaired haemostasis or increased bleeding tendency. The aim of this study was to compare intraoperative i-STAT(®) ACT values with commonly used thresholds of standard coagulation tests for the diagnosis of coagulopathy during paediatric non-cardiac surgery. We performed a prospective, observational study in a University Children's hospital and included 50 paediatric patients who underwent major elective, non-cardiac, surgery. The i-STAT(®) kaolin ACT test was obtained intraoperatively and compared to the commonly used threshold of standard coagulation tests (PT/INR, aPTT, and plasma fibrinogen level). A total of 181 blood samples were taken from 50 pediatric patients. Moderate correlation was found between ACT and aPTT (r = 0.694; p < 0.001), and all other coagulation tests. The median ACT values remained within the normal range throughout the entire surgical phase, while standard coagulation tests were mostly abnormal during surgery. Intraoperative measurement of ACT did not provide comparable thresholds of normal haemostasis as compared to standard coagulation testing.

Do lower cuff pressures reduce damage to the tracheal mucosa? A scanning electron microscopy study in neonatal pigs.

BACKGROUND: Modern high volume-low pressure (HVLP) endotracheal tubes (ETT) cuffs can seal the trachea using baseline cuff pressures (CP) lower than peak inspiratory airway pressures (PIP). The aim of the study was to determine whether this technique reduces the damage to the tracheal mucosa compared to constant CP of 20 cmH(2)O. METHODS: Eighteen piglets were intubated with an ID 4.0 mm HVLP cuffed ETT (Microcuff PET) and artificially ventilated with 20 cmH(2)O PIP and 5 cmH(2)O PEEP. Animals were randomly allocated to two groups of CP: group A (just seal; n = 9) and group B (20 cmH(2)O; n = 9), controlled constantly with a manometer during the following 4-h study period under sevoflurane anesthesia. After euthanasia, cuff position was marked in situ. Damage in the cuff region was evaluated with scanning electron microscopy (SEM) examination by grading of mucosal damage and by estimating percentage of intact mucosal area both by a blinded observer. RESULTS: Maximal CP to seal the trachea in group A ranged from 12 to 18 cmH(2)O (median: 14 cmH(2)O). Using a mixed effects model approach, the estimated mean effect of group B vs group A was an increase of 17.9% (SE 8.1%) higher proportion of pictures with an area of at least 5% intact mucosa (P = 0.042). CONCLUSION: Minimal sealing pressures with cyclic pressure changes from CP did not result in decreased damage to the tracheal mucosa compared to constant CP of 20 cmH(2)O in this short-term animal trial.

Reproducibility of thrombelastometry (ROTEM®): point-of-care versus hospital laboratory performance.

Thrombelastometry (ROTEM®) has gained wide acceptance in detecting and tailoring acquired hemostatic changes in adults and children. We investigated in this observational trial whether the reproducibility of this point-of-care testing was influenced by performance at the bedside or in the hospital laboratory. In addition, difference in time of performance between both measurements was compared. Perioperative blood samples obtained during major pediatric surgery were run in duplicate on two different ROTEM® devices located in the OR and in the hospital laboratory. The Bland-Altman test was used to compare differences of both measurements. ROTEM® measurements of 90 blood samples obtained from 24 children showed no overall clinically meaningful differences, whether they were performed bedside or in the hospital laboratory. Minor differences were found for the InTEM clot formation time (CFT) showing a mean bias of 10.79 seconds. Time saving was 11 minutes (8-16 minutes) if ROTEM® measurements were performed bedside (p < 0.001). In conclusion, there were minimal effects on ROTEM® measurements irrespective of whether they were performed in the hospital laboratory or at the bedside by a single trained staff member, while the latter saved valuable time.

Perioperative course of FXIII in children undergoing major surgery.

BACKGROUND: Acquired deficiency of FXIII because of perioperative hemodilution has been described several times in adults; however, data in children are scarce. We performed a prospective observational trial to evaluate the intraoperative course of FXIII in children undergoing elective major surgery. METHODS: Blood samples were repeatedly taken from 46 children aged 0.3-16 years undergoing major surgery. Concentrations of FXIII and fibrinogen, thrombelastometry by ROTEM®, and cell count were assessed intraoperatively. RESULTS: A significant decrease in FXIII concentration (median 60%; IQR 49-69%) was already noted at beginning of surgical procedures, while most ROTEM® traces remain unchanged. FXIII levels further deteriorated intraoperatively to minimal levels of 33% (15-61%). Lowest intraoperative clot strength (ExTEM) was 44 mm (34-50 mm), and fibrinogen plasma levels decreased to minimal levels of 130 mg·dl(-1) (95-160 mg·dl(-1) ). In 43 of 46 children, transfusion therapy was necessary. Despite of transfusion of fresh frozen plasma (cumulative total dose 22 ml·kg(-1) [11-32 ml·kg(-1) ]) in 21 of 46 children, FXIII level remains low in all children till the end of surgery at levels of 39% (20-46%). CONCLUSIONS: Coagulation factor XIII decreased early during major surgery owing to hemodilution. Overall intraoperative FXIII levels remain low despite of transfusion of fresh frozen plasma.

Resuscitation strategies from bupivacaine-induced cardiac arrest.

OBJECTIVES: Local anesthetic (LA) intoxication with cardiovascular arrest is a potential fatal complication of regional anesthesia. Lipid resuscitation has been recommended for the treatment of LA-induced cardiac arrest. Aim of the study was to compare four different rescue regimens using epinephrine and/or lipid emulsion and vasopressin to treat cardiac arrest caused by bupivacaine intoxication. METHODS: Twenty-eight piglets were randomized into four groups (4 × 7), anesthetized with sevoflurane, intubated, and ventilated. Bupivacaine was infused with a syringe driver via central venous catheter at a rate of 1 mg·kg(-1)·min(-1) until circulatory arrest. Bupivacaine infusion and sevoflurane were then stopped, chest compression was started, and the pigs were ventilated with 100% oxygen. After 1 min, epinephrine 10 µg·kg(-1) (group 1), Intralipid(®) 20% 4 ml·kg(-1) (group 2), epinephrine 10 µg·kg(-1) + Intralipid(®) 4 ml·kg(-1) (group 3) or 2 IU vasopressin + Intralipid(®) 4 ml·kg(-1) (group 4) were administered. Secondary epinephrine doses were given after 5 min if required. RESULTS: Survival was 71%, 29%, 86%, and 57% in groups 1, 2, 3, and 4. Return of spontaneous circulation was regained only by initial administration of epinephrine alone or in combination with Intralipid(®). Piglets receiving the combination therapy survived without further epinephrine support. In contrast, in groups 2 and 4, return of spontaneous circulation was only achieved after secondary epinephrine rescue. CONCLUSIONS: In cardiac arrest caused by bupivacaine intoxication, first-line rescue with epinephrine and epinephrine + Intralipid(®) was more effective with regard to survival than Intralipid(®) alone and vasopressin + Intralipid(®) in this pig model.

Evaluation of two devices for point-of-care testing of haemoglobin in neonatal pigs.

In veterinary medicine, point-of-care testing (POCT) techniques have become popular, since they provide immediate results and only small amounts of blood are needed. However, their accuracy is controversial. Pigs are often used for research purposes and accurate measurement of haemoglobin (Hb) is important during invasive procedures. The aim of this study was to evaluate two different Hb POCT devices in neonatal pigs. A prospective study with 57 pigs of 3-6 weeks of age, weighing 4.1-6.2 kg (median 5.1 kg) was performed. Fifty-seven blood samples were analysed for Hb using a conductivity-based and a photometrical POCT device and compared with a photometrical reference method. Statistical analysis was performed with Bland-Altman analysis, Spearman correlation and Passing-Bablok regression analysis. Hb values ranged from 32 to 108 g/L (median 80 g/L) using the reference method. The bias of the photometrical method (HemoCue(®)) to the reference method was -1 g/L, with limits of agreement (LOA) of -7 to 6 g/L. The conductivity-based method (i-STAT(®)) had a bias of -15 g/L with LOA from -24 to -6 g/L. There was a significant association between protein values and the bias of i-STAT versus CellDyn (r(2) = 0.27, P < 0.05) but not with the bias of HemoCue versus CellDyn (r(2) = 0.001, P = 0.79). The lower the protein values were, the lower the Hb values were measured by the i-STAT. The conductivity-based measurement of Hb constantly underestimated Hb values, whereas the photometrical method demonstrated a better accuracy and is therefore more reliable for on-site measurement of Hb in pigs.