Adjusting Acute Kidney Injury Kidney Disease: Improving Global Outcomes Urine Output Criterion for Predicted Body Weight Improves Prediction of Hospital Mortality.

BACKGROUND: Based on the Kidney Disease: Improving Global Outcomes (KDIGO) definitions, urine output, serum creatinine, and need for kidney replacement therapy are used for staging acute kidney injury (AKI). Currently, AKI staging correlates strongly with mortality and can be used as a predictive tool. However, factors associated with the development of AKI may affect its predictive ability. We tested whether adjustment for predicted (versus actual) body weight improved the ability of AKI staging to predict hospital mortality. METHODS: A total of 3279 patients who had undergone cardiac surgery in a university hospital were retrospectively analyzed. AKI was staged according to KDIGO criteria (standard staging) and after adjustment for hourly urine output adjusted by predicted body weight for each patient and each day of their hospital stay. RESULTS: The incidence of AKI (all stages) was 43% (predicted body weight adjusted) and 50% (standard staging), respectively ( P < .001). In sensitivity-specificity analyses for predicting hospital mortality, the area under the curve was significantly higher after adjustment for predicted body weight than with standard staging ( P = .002). CONCLUSIONS: Compared to standard staging, adjustment of urine output for predicted body weight increases the specificity and improves prediction of hospital mortality in patients undergoing cardiac surgery.

Impact of COVID-19-adapted guidelines using different airway management strategies on resuscitation quality in out-of-hospital-cardiac-arrest - a randomised manikin study.

BACKGROUND: Although airway management for paramedics has moved away from endotracheal intubation towards extraglottic airway devices in recent years, in the context of COVID-19, endotracheal intubation has seen a revival. Endotracheal intubation has been recommended again under the assumption that it provides better protection against aerosol liberation and infection risk for care providers than extraglottic airway devices accepting an increase in no-flow time and possibly worsen patient outcomes. METHODS: In this manikin study paramedics performed advanced cardiac life support with non-shockable (Non-VF) and shockable rhythms (VF) in four settings: ERC guidelines 2021 (control), COVID-19-guidelines using videolaryngoscopic intubation (COVID-19-intubation), laryngeal mask (COVID-19-Laryngeal-Mask) or a modified laryngeal mask modified with a shower cap (COVID-19-showercap) to reduce aerosol liberation simulated by a fog machine. Primary endpoint was no-flow-time, secondary endpoints included data on airway management as well as the participants' subjective assessment of aerosol release using a Likert-scale (0 = no release-10 = maximum release) were collected and statistically compared. Continuous Data was presented as mean ± standard deviation. Interval-scaled Data were presented as median and Q1 and Q3. RESULTS: A total of 120 resuscitation scenarios were completed. Compared to control (Non-VF:11 ± 3 s, VF:12 ± 3 s) application of COVID-19-adapted guidelines lead to prolonged no-flow times in all groups (COVID-19-Intubation: Non-VF:17 ± 11 s, VF:19 ± 5 s;p ≤ 0.001; COVID-19-laryngeal-mask: VF:15 ± 5 s,p ≤ 0.01; COVID-19-showercap: VF:15 ± 3 s,p ≤ 0.01). Compared to COVID-19-Intubation, the use of the laryngeal mask and its modification with a showercap both led to a reduction of no-flow-time(COVID-19-laryngeal-mask: Non-VF:p = 0.002;VF:p ≤ 0.001; COVID-19-Showercap: Non-VF:p ≤ 0.001;VF:p = 0.002) due to a reduced duration of intubation (COVID-19-Intubation: Non-VF:40 ± 19 s;VF:33 ± 17 s; both p ≤ 0.01 vs. control, COVID-19-Laryngeal-Mask (Non-VF:15 ± 7 s;VF:13 ± 5 s;p > 0.05) and COVID-19-Shower-cap (Non-VF:15 ± 5 s;VF:17 ± 5 s;p > 0.05). The participants rated aerosol liberation lowest in COVID-19-intubation (median:0;Q1:0,Q3:2;p < 0.001vs.COVID-19-laryngeal-mask and COVID-19-showercap) compared to COVID-19-shower-cap (median:3;Q1:1,Q3:3 p < 0.001vs.COVID-19-laryngeal-mask) or COVID-19-laryngeal-mask (median:9;Q1:6,Q3:8). CONCLUSIONS: COVID-19-adapted guidelines using videolaryngoscopic intubation lead to a prolongation of no-flow time. The use of a modified laryngeal mask with a shower cap seems to be a suitable compromise combining minimal impact on no-flowtime and reduced aerosol exposure for the involved providers.

Incidence, Mortality, and Characteristics of 18 Pediatric Perioperative Cardiac Arrests: An Observational Trial From 22,650 Pediatric Anesthesias in a German Tertiary Care Hospital.

BACKGROUND: Recently, a very low incidence of 3 per 10,000 and a mortality of 30% were reported for pediatric perioperative cardiac arrest (POCA). However, high-risk patients, namely children already anesthetized on the intensive care unit (ICU), were excluded. This study investigates the incidence and mortality of POCA in children in whom anesthesia was induced in the ICU or in the operating room using real-world data. In addition, different classifications of POCA were compared with respect to outcome relevance. METHODS: This is a retrospective observational study conducted at a German level 1 perinatal center and tertiary care hospital between 2008 and 2018. Children ≤15 years who underwent an anesthetic procedure and suffered from POCA (defined as any condition requiring chest compressions and/or defibrillation) from the beginning of care provided by an anesthesiologist to 60 minutes after anesthesia or sedation were included. Primary end points were incidence and mortality of POCA in children with anesthesia induced in the ICU versus in the operating room. Secondary end points included incidences and outcomes with respect to the pathophysiological cause (respiratory versus circulatory associated). RESULTS: There were 18 POCA during 22,650 anesthetic procedures (incidence 7.9 per 10,000; 95% confidence interval [CI], 4.7-12.5). Thirty-day mortality was 3.5 per 10,000 (95% CI, 1.5-6.9). Incidence and mortality were higher in children in whom anesthesia was induced in the ICU versus in the operating room (incidence: 131.6; 95% CI, 57 to 257.6 versus 4.5; 95% CI, 2.2-8.3; P < .001; and mortality: 82.2; 95% CI, 26.7-190.8 versus 1.4; 95% CI, 0.3-3.9; P < .001). Mortality in circulatory-induced POCA (n = 8; 44%) was 100%, in respiratory-induced POCA (n = 9; 50%) 0% (P < .001). CONCLUSIONS: Children with anesthesia induction in the ICU represent a high-risk population for POCA and POCA-associated mortality. POCA classification should be based on the individual cause (respiratory versus circulatory) rather than on the perioperative phase or the responsible specialty.

Systolic-dicrotic notch pressure difference can identify tachycardic patients with septic shock at risk of cardiovascular decompensation following pharmacological heart rate reduction.

BACKGROUND: During sepsis, heart rate (HR) reduction could be a therapeutic target, but identification of responders (non-compensatory tachycardia) and non-responders (compensatory for 'fixed' stroke volume [SV]) is challenging. We tested the ability of the difference between systolic and dicrotic pressure (SDPdifference), which reflects the coupling between myocardial contractility and a given afterload, in discriminating the origin of tachycardia. METHODS: In this post hoc analysis of 45 patients with septic shock with persistent tachycardia, we characterised features of haemodynamic response focusing on SDPdifference, classifying patients according to variations in arterial dP/dtmax after 4 h of esmolol administration to maintain HR <95 beats min-1. A cut-off value of 0.9 mm Hg ms-1 was used for group allocation. RESULTS: After reducing HR, arterial dP/dtmax remained above the cut-off in 23 patients, whereas it decreased below the cut-off in 22 patients (from 0.99 [0.37] to 0.63 [0.16] mm Hg ms-1; mean [SD], P<0.001). At baseline, patients with decreased dP/dtmax after esmolol had lower SDPdifference than those with higher dP/dtmax (40 [19] vs 53 [16] mm Hg, respectively; P=0.01). The SDPdifference remained unchanged after esmolol in the higher dP/dtmax group (49 [16] mm Hg), whereas it decreased significantly in patients with lower dP/dtmax (29 [11] mm Hg; P<0.001). In the latter, the HR reduction resulted in a significant cardiac output reduction with unchanged SV, whereas in patients with higher dP/dtmax SV increased (from 48 [12] to 67 [14] ml; P<0.001) with maintained cardiac output. CONCLUSIONS: A decrease in SDPdifference could discriminate between compensatory and non-compensatory tachycardia, revealing a covert loss of myocardial contractility not detected by conventional echocardiographic parameters and deteriorating after HR reduction with esmolol. CLINICAL TRIAL REGISTRATION: NCT02188888.

The Effect of Propofol and Dexmedetomidine Sedation on Norepinephrine Requirements in Septic Shock Patients: A Crossover Trial.

OBJECTIVES: Propofol-based sedation may increase hemodynamic instability by decreasing vascular tone and venous return. Incremental exogenous catecholamines doses may be required to counteract such effects, aggravating the deleterious effects of sympathetic overstimulation. α-2 adrenergic agonists have been reported to decrease norepinephrine requirements in experimental septic shock. The aim of the present study is to test the hypothesis that switching from sedation with propofol to the α-2 agonist dexmedetomidine may decrease norepinephrine doses in septic shock. DESIGN: Prospective open-label crossover study. SETTINGS: University hospital, ICU. PATIENTS: Thirty-eight septic shock patients requiring norepinephrine to maintain adequate mean arterial pressure and needing deep sedation with propofol and remifentanil to maintain a Richmond Agitation-Sedation Scale score between -3 and -4. INTERVENTIONS: An initial set of measurements including hemodynamics, norepinephrine doses, and depth of sedation were obtained during sedation with propofol. Propofol was then replaced by dexmedetomidine and a second set of data was obtained after 4 hours of dexmedetomidine infusion. Sedation was switched back to propofol, and a final set of measurements was obtained after 8 hours. A Richmond Agitation-Sedation Scale score between -3 and -4 was maintained during the study period. MEASUREMENTS AND MAIN RESULTS: Norepinephrine requirements decreased from 0.69 ± 0.72 µg/kg/min before dexmedetomidine to 0.30 ± 0.25 µg/kg/min 4 hours after dexmedetomidine infusion, increasing again to 0.42 ± 0.36 µg/kg/min while on propofol 8 hours after stopping dexmedetomidine (p < 0.005). Dexmedetomidine dosage was 0.7 ± 0.2 µg/kg/hr. Before and after dexmedetomidine infusion, sedative doses remained unchanged (propofol 2.6 ± 1.2 vs 2.6 ± 1.2 mg/kg/hr; p = 0.23 and remifentanil 1.27 ± 0.17 vs 1.27 ± 0.16 µg/kg/hr; p = 0.52, respectively). Richmond Agitation-Sedation Scale was -4 (-4 to -3) before, -4 (-4 to -3) during, and -4 (-4 to -4) after dexmedetomidine (p = 0.07). CONCLUSIONS: For a comparable level of sedation, switching from propofol to dexmedetomidine resulted in a reduction of catecholamine requirements in septic shock patients.

A new complimentary web-based tool for manual analysis of microcirculation videos: Validation of the Capillary Mapper against the current gold standard AVA 3.2.

OBJECTIVE: The aim of the current study was to compare a newly developed web-based freely accessible software program for manual analysis of the microcirculation, the Capillary Mapper (CM), with AVA 3.2 software (AVA; MicroVision Medical B.V., Amsterdam, The Netherlands), which is the current gold standard for analysis of microcirculation videos. METHODS: A web-based software program was developed, which enables manual analysis of videos of the microcirculation to be carried out according to recommendations of the 2018 consensus conference. A set of 50 high quality microcirculation videos was analyzed with AVA and CM with respect to total vessel density, perfused vessel density, proportion of perfused vessels, and the microvascular flow index. RESULTS: Comparison of the mean values derived from manual analysis with CM and AVA revealed no significant differences in microcirculatory variables. Analysis according to Bland and Altman revealed an acceptable bias between manual analysis with the CM and AVA for all variables tested with sufficient limits of agreement. The analysis of intraclass correlation showed "excellent" agreement for all microcirculatory variables analyzed. CONCLUSIONS: The newly developed CM was successfully validated for manual analyses of microcirculation videos against the current gold standard, the software AVA 3.2.

Indications and measures of medical emergency teams: a retrospective evaluation of in-hospital emergency operations of the German Resuscitation Register.

BACKGROUND: The present study examines characteristics and interventions of medical emergency teams (MET) in in-hospital emergency care. METHODS: Analysis of all in-hospital emergencies in patients ≥18 years at 62 hospitals with established MET from the database of the German Resuscitation Registry between 2014-2019. The evaluation covered indications for activation using the ABCDE-scheme, time intervals of arrival and patient care as well as the performed invasive/medical interventions. RESULTS: Out of 62 hospitals 14,166 in-hospital emergencies (male: 8033 [56.7%]; mean age: 64±18 years) were included. Causes of activation were circulation (5760 [40.7%]), disability (4076 [28.8%]), breathing (3649 [25.8%]) and airway-problems (1589 [11.2%]). Average arrival time at the emergency scene was 4±3 minutes, supply time of MET was 24±23 minutes. Endotracheal intubation was required in 1757 (12.4%) and difficult intubation occurred in 201 (11.4%) patients with the necessity for cricothyroidotomy in eight cases (3.9%). Invasive blood-pressure-measurement was indicated in 1074 (7.6%) patients. Catecholamines were required for hemodynamic stabilization in 2421 (17.1%) patients (norepinephrine: 1520 [10.7%], epinephrine: 430 [3.0%], dobutamine: 26 [0.2%]). CONCLUSIONS: Current in-hospital emergency care requires special skills in invasive hemodynamic and airway interventions. Recommendations from professional societies are necessary to optimize equipment (e.g. videolaryngoscopy, invasive blood pressure management), training, care algorithms and staff composition against the background of an increasing shortage of resources in the healthcare system.

Efficacy of in-bed chest compressions depending on provider position during in-hospital cardiac arrest: a controlled manikin study.

BACKGROUND: In contrast to the pre-hospital environment, patients with in-hospital cardiac arrest are usually lying in a hospital bed. Interestingly, there are no current recommendations for optimal provider positioning. The present study evaluates in bed chest compression quality in different provider positions during in-hospital-cardiac-arrest. METHODS: Paramedics conducted four resuscitation scenarios: manikin lying on the floor with provider position kneeling next to the manikin (control group), manikin lying in a hospital bed with the provider kneeling astride, kneeling beside or standing next to the manikin. A resuscitation board was not used according to the current guideline recommendations. Quality of resuscitation, compression depth, compression rate and percentage of compressions with complete chest rebound were recorded. Afterwards, the paramedics were asked about subjective efficiency and fatigue. Data were analyzed using Generalized-Linear-Mixed-Models and, in addition, by non-parametric Friedman test. RESULTS: A total of 60 participants were recruited. The total quality of chest compressions was significantly higher in floor-based control position compared to the standing (P<.001) and both kneeling positions (P<.05). Also, the compression depth was significantly more guideline compliant in the control (P<.001) and the kneeling position (P<.05) compared to the standing position. The compression frequency as well as the complete chest wall recoil did not differ significantly. The standing position was rated as more fatiguing than the other positions (p≤0.001), kneeling beside as subjectively more efficient than the standing position (P<0.001). CONCLUSIONS: In case of an in-bed resuscitation, high quality chest compressions are possible. Kneeling astride or beside the patient should be preferred because these positions demonstrated a good chest compression quality and were more efficient and less exhausting.

Incidence, characteristics and risk factors for perioperative cardiac arrest and 30-day-mortality in preterm infants requiring non-cardiac surgery.

STUDY OBJECTIVE: To determine 30-day-mortality, incidence and characteristics of perioperative cardiac arrest as well as the respective independent risk factors in preterm infants undergoing non-cardiac surgery. DESIGN: Retrospective observational Follow-up-study. SETTING: Bielefeld University Hospital, a German tertiary care hospital. PATIENTS: Population of 229 preterm infants (age < 37th gestational week at the time of surgery) who underwent non-cardiac surgery between 01/2008-12/2018. MEASUREMENTS: Primary endpoint was overall 30-day-mortality. Secondary endpoints were the incidence of perioperative cardiac arrest and identification of independent risk factors. We performed univariate and multivariate analyses and calculated odds ratios (OR) for risk factors associated with these endpoints. MAIN RESULTS: 30-day-mortality was 10.9% and perioperative mortality 0.9%. Univariate risk factors for 30-day-mortality were perioperative cardiac arrest (OR,12.5;95%CI,3.1 to 50.3), comorbidities of lungs (OR,3.7;95%CI,1.2 to 11.3) and gastrointestinal tract (OR,3.5;95%CI,1.3 to 9.6); sepsis (OR,3.6;95%CI,1.4 to 9.5); surgery between 22:01-7:00 (OR,7.3;95%CI,2.4 to 21.7); emergency (OR,4.5;95%CI,1.6 to 12.4); pre-existing catecholamine therapy (OR,5.0;95%CI,2.1 to 11.9). Multivariate logistic regression indicated that perioperative cardiac arrest (OR,13.9;95%CI,2.7 to 71.3), low body weight (weight < 1000 g: OR,26.0;95%CI,3.2 to 212; 1000-1499 g: OR,10.3; 95%CI,1.1 to 94.9 compared to weight > 2000 g), and time of surgery (OR,5.9;95%CI,1.6 to 21.3) for 22:01-7:00 compared to 7:01-15:00) were the major independent risk factors of mortality. Incidence of perioperative cardiac arrests was 3.9% (9 of 229;95%CI,1.8 to 7.3). Univariate risk factors were congenital anomalies of the airways (OR,4.7;95%CI,1.2 to 20.3), lungs (OR,4.7;95%CI,1.2 to 20.3) and heart (OR,8.0;95%CI,2 to 32.2), pre-existing catecholamine therapy (OR,59.5;95%CI,3.4 to 1039), specifically, continuous infusions of epinephrine (OR,432;95%CI,43.2 to 4318). CONCLUSIONS: 30-day-mortality and the incidence of perioperative cardiac arrest of preterms undergoing non-cardiac surgery were higher than previously reported. The identified independent risk factors may improve interdisciplinary perioperative risk assessment, optimal preoperative stabilization and scheduling of optimal surgical timing.

Impact of COVID-19-adapted guidelines on resuscitation quality in out-of-hospital-cardiac-arrest: a manikin study.

BACKGROUND: The aim of this study is to evaluate the effects of European Resuscitation Council (ERC) COVID-19-guidelines on resuscitation quality emphasizing advanced airway management in out-of-hospital-cardiac-arrest. METHODS: In a manikin study paramedics and emergency physicians performed advanced cardiac life support in three settings: ERC guidelines 2015 (control), COVID-19-guidelines as suggested with minimum staff (COVID-19-minimal-personnel); COVID-19-guidelines with paramedics and an emergency physician (COVID-19-advanced-airway-manager). Main outcome measures were no-flow-time, quality metrics as defined by ERC and time intervals to first chest compression, oxygen supply, intubation and first rhythm analysis. Data were presented as mean±standard deviation. RESULTS: Thirty resuscitation scenarios were completed. No-flow-time was markedly prolonged in COVID-19-minimal-personnel (113±37 s) compared to control (55±9 s) and COVID-19-advanced-airway-manager (76±38s; P<0.001 each). In both COVID-19-groups chest compressions started later (COVID-19-minimal-personnel: 32±6 s; COVID-19-advanced-airway-manager: 37±7 s; each P<0.001 vs. control [21±5 s]), but oxygen supply (COVID-19-minimal-personnel: 29±5 s; COVID-19-advanced-airway-manager: 34±7 s; each P<0.001 vs. control [77±19 s]) and first intubation attempt (COVID-19-minimal-personnel: 111±14 s; COVID-19-advanced-airway-manager: 131±20 s; each P<0.001 vs. control [178±44 s]) were performed earlier. However, time interval to successful intubation was similar (control: 198±48 s; COVID-19-minimal-personnel: 181±42 s; COVID-19-advanced-airway-manager: 130±25 s) due to a longer intubation time in COVID-19-minimal-personnel (61±35 s) compared to COVID-19-advanced-airway-manager (P=0.002) and control (19±6 s; P<0.001). Time to first rhythm analysis was more than doubled in COVID-19-minimal-personnel (138±96 s) compared to control (50±12 s; P<0.001). CONCLUSIONS: Delayed chest compressions and prolonged no-flow-time markedly reduced the quality of resuscitation. These negative effects were attenuated by increasing the number of staff and by adding an experienced airway manager. The use of endotracheal intubation for reducing aerosol release during resuscitation should be discussed critically as its priorization is associated with an increase in no-flow-time.

Comparison of first-line and second-line terlipressin versus sole norepinephrine in fulminant ovine septic shock.

The Surviving Sepsis Guidelines suggest the use of vasopressin in case of catecholamine-refractory septic shock. Terlipressin (TP) as a V1-selective AVP analogue is a potential alternative, though data regarding the first-line administration in septic shock are scarce. The present study explored and compared the effects of first-line vs. second-line infusion of TP or sole norepinephrine regarding organ function, fluid and norepinephrine requirements and survival in fulminant ovine septic shock. Peritoneal sepsis was induced in 23 ewes after laparotomy and faecal withdrawal from the caecum. After onset of shock, causal and supportive sepsis therapy (antibiotics, peritoneal lavage, fluids and open-label norepinephrine) was performed in all animals. Concurrently, animals were randomized to receive 0.9% sodium chloride (control group) or TP (2 µg∙kg-1∙h-1, first-line group) after shock onset. In the second-line TP group, TP (2 µg∙kg-1∙h-1) was started once norepinephrine requirements exceeded 0.5 µg∙kg-1∙min-1. No significant differences were found between groups regarding survival, haemodynamics as well as fluid- and catecholamine-requirements. Kidney function and electron microscopic kidney injury were comparable between groups. In the present model of fulminant ovine septic shock, first-line TP infusion had no significant effect on fluid and norepinephrine requirements or organ dysfunction as compared to second-line TP infusion or placebo.

γ-tocopherol nebulization decreases oxidative stress, arginase activity, and collagen deposition after burn and smoke inhalation in the ovine model.

More than 20,000 burn injury victims suffer from smoke inhalation injury in the United States annually. In an ovine model of acute lung injury, γ-tocopherol had a beneficial effect when nebulized into the airway. We hypothesize that γ-tocopherol scavenges reactive oxygen species (ROS) and reactive nitrogen species resulting from burn and smoke inhalation injury and that these ROS/reactive nitrogen species activate the arginase pathway, leading to increased collagen deposition and decreased pulmonary function. To test this hypothesis, ewes were operatively prepared for chronic study, then they were randomly divided into groups (n = 8): uninjured, injured, or injured with nebulization (γ-tocopherol [950 mg/g] and α-tocopherol [40 mg/g] from hours 3 to 48 after the injury). The injury, under deep anesthesia, consisted of a 20% total body surface burn and 36 breaths of cotton smoke; all animals were killed after 3 weeks. Treatment increased lung γ-tocopherol at 3 weeks after γ-tocopherol nebulization compared with injured sheep (1.75 ± 0.62 nmol/g vs. 0.45 ± 0.06, P < 0.05). The expression of dimethylarginine dimethylaminohydrolase-2, which degrades asymmetrical dimethylarginine, a nitric oxide synthase inhibitor, significantly increases with γ-tocopherol treatment compared with injured sheep (P < 0.05). Arginase activity (0.15 ± 0.02 µM urea/µg protein vs. 0.24 ± 0.009, P < 0.05), ornithine aminotransferase (11,720 ± 888 vs. 13,170 ± 1,775), and collagen deposition (0.62 ± 0.12 µM hydroxyproline/µg protein vs. 1.02 ± 0.13, P < 0.05) significantly decrease with γ-tocopherol compared with injured animals without γ-tocopherol. The decreases in arginase and collagen with γ-tocopherol are associated with significantly increased diffusion capacity (P < 0.05) and decreased lung wet-to-dry ratio (P < 0.05). Smoke-induced chronic pulmonary dysfunction is mediated through the ROS/asymmetrical dimethylarginine/arginase pathway, and ROS scavengers such as γ-tocopherol may be a potential therapeutic management of burn patients with inhalation injury.

Nebulization with γ-tocopherol ameliorates acute lung injury after burn and smoke inhalation in the ovine model.

We hypothesize that the nebulization of γ-tocopherol (g-T) in the airway of our ovine model of acute respiratory distress syndrome will effectively improve pulmonary function following burn and smoke inhalation after 96 h. Adult ewes (n = 14) were subjected to 40% total body surface area burn and were insufflated with 48 breaths of cotton smoke under deep anesthesia, in a double-blind comparative study. A customized aerosolization device continuously delivered g-T in ethanol with each breath from 3 to 48 h after the injury (g-T group, n = 6), whereas the control group (n = 5) was nebulized with only ethanol. Animals were weaned from the ventilator when possible. All animals were killed after 96 h, with the exception of one untreated animal that was killed after 64 h. Lung g-T concentration significantly increased after g-T nebulization compared with the control group (38.5 ± 16.8 vs. 0.39 ± 0.46 nmol/g, P < 0.01). The PaO(2)/FIO(2) ratio was significantly higher after treatment with g-T compared with the control group (310 ± 152 vs. 150 ± 27.0, P < 0.05). The following clinical parameters were improved with g-T treatment: pulmonary shunt fraction, peak and pause pressures, lung bloodless wet-to-dry weight ratios (2.9 ± 0.87 vs. 4.6 ± 1.4, P < 0.05), and bronchiolar obstruction (2.0% ± 1.1% vs. 4.6% ± 1.7%, P < 0.05). Nebulization of g-T, carried by ethanol, improved pulmonary oxygenation and markedly reduced the time necessary for assisted ventilation in burn- and smoke-injured sheep. Delivery of g-T into the lungs may be a safe, novel, and efficient approach for management of acute lung injury patients who have sustained oxidative damage to the airway.

Burn and smoke injury activates poly(ADP-ribose)polymerase in circulating leukocytes.

The nuclear enzyme poly(ADP-ribose)polymerase (PARP) plays a significant role in the pathogenesis of various forms of critical illness. DNA strand breaks induced by oxidative and nitrative stress trigger the activation of PARP, and PARP, in turn, mediates cell death and promotes proinflammatory responses. Until recently, most studies focused on the role of PARP in solid organs such as heart, liver, and kidney. We investigated the effect of burn and smoke inhalation on the levels of poly(ADP-ribosylated) proteins in circulating sheep leukocytes ex vivo. Adult female merino sheep were subjected to burn injury (2× 20% each flank, 3 degrees) and smoke inhalation injury (insufflated with a total of 48 breaths of cotton smoke) under deep anesthesia. Arterial and venous blood was collected at baseline, immediately after the injury and 1 to 24 h after the injury. Leukocytes were isolated with the Histopaque method. The levels of poly(ADP-ribosyl)ated proteins were determined by Western blotting. The amount of reactive oxygen species was quantified by the OxyBlot method. To examine whether PARP activation continues to increase ex vivo in the leukocytes, blood samples were incubated at room temperature or at 37°C for 3 h with or without the PARP inhibitor PJ34. To investigate whether the plasma of burn/smoke animals may trigger PARP activation, burn/smoke plasma was incubated with control leukocytes in vitro. The results show that burn and smoke injury induced a marked PARP activation in circulating leukocytes. The activity was the highest immediately after injury and at 1 h and decreased gradually over time. Incubation of whole blood at 37°C for 3 h significantly increased poly(ADP-ribose) levels, indicative of the presence of an ongoing cell activation process. In conclusion, PARP activity is elevated in leukocytes after burn and smoke inhalation injury, and the response parallels the time course of reactive oxygen species generation in these cells.

Pseudomonas aeruginosa is associated with increased lung cytokines and asymmetric dimethylarginine compared with methicillin-resistant Staphylococcus aureus.

The objective of the study was to investigate pulmonary responses to Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) using ovine and mice models of sepsis with emphasis on lung cytokine expression, asymmetric dimethylarginine (ADMA) concentration, and the arginase pathway. Sheep were instilled with either MRSA, P. aeruginosa, or saline under deep anesthesia; mechanically ventilated; resuscitated with fluid; and killed after 24 h. Mice were instilled with either MRSA, P. aeruginosa, or saline under deep anesthesia and killed after 8 h. Lungs were assessed for ADMA concentration, arginase activity, oxidative stress, and cytokine expression, and plasma was assessed for nitrate/nitrite concentrations. The severity of lung injury was more pronounced in P. aeruginosa sepsis compared with MRSA. The significant changes in sheep lung function after P. aeruginosa sepsis were associated with significantly increased ADMA concentrations and arginase activity compared with MRSA. However, the plasma concentration of nitrites and nitrates were significantly increased in MRSA sepsis compared with P. aeruginosa sepsis. In the mice model, P. aeruginosa significantly increased lung cytokine expression (IL-1 and IL-13), protein oxidation, and arginase activity compared with MRSA. Our data suggest that the greater expression of cytokines and ADMA concentrations may be responsible for severity of acute lung injury in P. aeruginosa sepsis. The lack of arginase activity may explain the greater nitric oxide production in MRSA sepsis.

Acute lung injury-induced collagen deposition is associated with elevated asymmetric dimethylarginine and arginase activity.

Evidence suggests that lung structure and function are partly maintained by a balance between the competing arginine-metabolizing enzymes arginase and nitric oxide (NO) synthase. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthase. It is metabolized by dimethylarginine dimethylaminohydrolase 2 (DDAH-2), which is oxidant-sensitive. The mechanism that induces excess lung collagen deposition in burned patients has not yet been explored. Our objective was to investigate the role of ADMA and the arginase pathway in acute lung injury. An ovine model for burn and smoke inhalation injury was used to assess excess lung collagen deposition. Sheep were deeply anesthetized during the injury, mechanically ventilated, resuscitated with fluid, and killed after either 2 or 3 weeks. Lungs were assessed histologically and biochemically for collagen content, arginase activity, lipid peroxidation product and antioxidant concentration, and protein concentrations. Plasma was assessed for amino acid and nitrate/nitrite concentrations. Burn and inhalation injury resulted in significantly reduced pulmonary function and increased lung collagen deposition. These physiological changes were associated with significantly increased lung arginase activity, collagen synthesis precursor ornithine aminotransferase, and ornithine decarboxylase, which is associated with cell proliferation. Significant decreases in plasma nitrate/nitrite after injury were associated with increased lung ADMA concentrations and decreased DDAH-2 expression. The decreased DDAH-2 expression was associated with significantly increased lipid peroxidation product and decreased antioxidant content in the lung. These data support that excess lung collagen deposition and reduced pulmonary function in acute lung injury after burn and inhalation injury are mediated through the arginase pathway.

The Angiotensin-converting enzyme inhibitor captopril inhibits poly(adp-ribose) polymerase activation and exerts beneficial effects in an ovine model of burn and smoke injury.

We investigated the effect of the angiotensin-converting enzyme (ACE) inhibitor captopril in a clinically relevant ovine model of smoke and burn injury, with special reference to oxidative stress and activation of poly(ADP-ribose) polymerase, in the lung and in circulating leukocytes. Female, adult sheep (28-40 kg) were divided into three groups. After tracheostomy and under deep anesthesia, both vehicle-control-treated (n = 5) and captopril-treated (20 mg/kg per day, i.v., starting 0.5 h before the injury) (n = 5) groups were subjected to 2 × 20%, third-degree burn injury and were insufflated with 48 breaths of cotton smoke. A sham group not receiving burn/smoke was also studied (n = 5). Animals were mechanically ventilated and fluid resuscitated for 24 h in the awake state. Burn and smoke injury resulted in an upregulation of ACE in the lung, evidenced by immunohistochemical determination and Western blotting. Burn and smoke injury resulted in pulmonary dysfunction, as well as systemic hemodynamic alterations. Captopril treatment of burn and smoke animals improved PaO2/FiO2 ratio and pulmonary shunt fraction and reduced the degree of lung edema. There was a marked increase in PAR levels in circulating leukocytes after burn/smoke injury, which was significantly decreased by captopril. The pulmonary level of ACE and the elevated pulmonary levels of transforming growth factor ß in response to burn and smoke injury were significantly decreased by captopril treatment. Our results suggest that the ACE inhibitor captopril exerts beneficial effects on the pulmonary function in burn/smoke injury. The effects of the ACE inhibitor may be related to the prevention of reactive oxygen species-induced poly(ADP-ribose)polymerase overactivation. Angiotensin-converting enzyme inhibition may also exert additional beneficial effects by inhibiting the expression of the profibrotic mediator transforming growth factor ß.