Epidemiological Analysis of the Emergency Vascular Access in Pediatric Trauma Patients: Single-Center Experience of Intravenous, Intraosseous, Central Venous, and Arterial Line Placements.

Vascular access in severely injured pediatric trauma patients is associated with time-critical circumstances and low incidences, whereas only scarce literature on procedure performance is available. The purpose of this study was to analyze the performance of different vascular access procedures from the first contact at the scene until three hours after admission. Intubated pediatric trauma patients admitted from the scene to a single Level I trauma center between 2008 and 2019 were analyzed regarding intravenous (IV) and intraosseous (IO) accesses, central venous catheterization (CVC) and arterial line placement. Sixty-five children with a median age of 14 years and median injury severity score of 29 points were included, of which 62 (96.6%) underwent successful prehospital IV or IO access by emergency medical service (EMS) physicians, while it failed in two children (3.1%). On emergency department (ED) admission, IV cannulas of prehospital EMS had malfunctions or were dislodged in seven of 55 children (12.7%). IO access was performed in 17 children without complications, and was associated with younger age, higher injury severity and higher mortality. Fifty-two CVC placements (58 attempts) and 55 arterial line placements (59 attempts) were performed in 45 and 52 children, respectively. All CVC and arterial line placements were performed in the ED, operating room (OR) and intensive care unit (ICU). Ten mechanical complications related to CVC placement (17.8%) and seven related to arterial line placement (10.2%) were observed, none of which had outcome-relevant consequences. This case series suggests that mechanical issues of vascular access may frequently occur, underlining the need for special preparedness in prehospital, ED, ICU and OR environments.

Tracheal Tube Misplacement after Emergency Intubation in Pediatric Trauma Patients: A Retrospective, Exploratory Study.

Inadvertent tracheal tube misplacement and particularly endobronchial intubation are well-known complications of emergency endotracheal intubation (ETI) in pediatric trauma patients, which require repositioning of the tube to avoid impairment of gas exchange. The main aim of study was to identify the frequency of tube misplacement and associated factors of pediatric trauma patients who received ETI either by prehospital physician-staffed emergency medical service (EMS), or at emergency department (ED) admission to a single level-1 trauma center. Sixty-five patients (median age 14 years and median injury severity score 29) were included. Of these, 30 underwent helicopter EMS ETI, 29 ground EMS ETI, and 6 ED ETI. Seventeen cases (26%) of tracheal tube misplacement were recognized. After multivariable analysis, tracheal tube misplacement was independently negatively associated with body weight (OR 0.86; 95% CI, 0.76-0.99; p = 0.032) and helicopter EMS ETI (OR 0.20; 95% CI, 0.04-0.97; p = 0.036). Two of nineteen patients received tube thoracostomy due to endobronchial intubation. Mortality and length of stay were comparable in patients with misplaced tubes and correctly placed tubes. The results suggest that particularly small children require attention to avoid tracheal tube misplacement, which emphasizes the need for special training. Helicopter EMS physicians' expertise might be beneficial in prehospital pediatric trauma patients requiring advanced airway management.

Laparoscopic versus robot-assisted Nissen fundoplication in an infant pig model.

PURPOSE: Surgical robots are designed to facilitate dissection and suturing, although objective data on their superiority are lacking. This study compares conventional laparoscopic Nissen fundoplication (CLNF) to robot-assisted Nissen fundoplication (RANF) using computer-based workflow analysis in an infant pig model. METHODS: CLNF and RANF were performed in 12 pigs. Surgical workflow was segmented into phases. Time required to perform specific actions was compared by t test. The quality of knot-tying was evaluated by a skill scoring system. Cardia yield pressure (CYP) was determined to test the efficacy of the fundoplications, and the incidence of complications was compared. RESULTS: There was no difference in average times to complete the various phases, despite faster robotic knot-tying (p = 0.001). Suturing quality was superior in CLNF (p = 0.02). CYP increased similarly in both groups. Workflow-interrupting hemorrhage and pneumothorax occurred more frequently during CLNF (p = 0.040 and 0.044, respectively), while more sutures broke during RANF (p = 0.001). CONCLUSION: The robot provides no clear temporal advantage compared to conventional laparoscopy for fundoplication, although suturing was faster in RANF. Fewer complications were noted using the robot. RANF and CLNF were equally efficient anti-reflux procedures. For robotic surgery to manifest its full potential, more complex operations may have to be evaluated.

Indocyanine green R15 ratio depends directly on liver perfusion flow rate.

BACKGROUND: Indocyanine green (ICG) is a synthetic dye that is widely used to evaluate liver function in critically ill patients, before liver resection or after liver transplantation. Controversy still exists about the impact exerted on the ICG ratio after 15 min (ICG R15) by differences in liver perfusion rates, hyperdynamic states, or patient cardiac output. We studied the role of different liver perfusion rates on the ICG R15 ratio in a normothermic extracorporeal liver perfusion system under standardized conditions. METHODS: Livers from landrace pigs (40-50 kg) were perfused with fresh porcine blood. Normal and high perfusion rates were defined as 1 ml and 2 ml/g liver/min, respectively. Perfusate pressure of the hepatic artery and portal vein were within the physiological range in both groups. According to manufacturer's instructions, 0.5 mg of ICG per kg was applied and the ICG R15 was calculated. Calculations were based on fifteen experiments in five liver perfusions. Bile production, liver function and histology were analyzed. RESULTS: All perfusions were characterized by physiological bile production, lack of hepatocellular damage and normal histology. ICG R15 ratio in group I, perfused with 1 ml/g liver, was 18.9 +/- 6%. In group II, perfused with 2 ml/g liver, the ICG R15 ratio was 7.2 +/- 3%. The difference between groups 1 and 2 was statistically significant (p < 0.05). CONCLUSION: ICG R15 is reliable within one group at defined perfusion rates. Doubled perfusion rates contribute to higher ICG clearance. For clinical application we would like to suggest considering cardiac output of the patient for interpretation of ICG ratios.

Periportal oedema of the liver: correlation with clinical and paraclinical parameters in polytraumatic patients.

PURPOSE: To clarify the occurrence of periportal edema in polytraumatic patients. MATERIALS AND METHODS: Retrospective analysis of computed tomography (CT) scans from 74 polytraumatic patients (12 females, 62 males; 14-88 years old, median 32 years) performed shortly after the trauma. Periportal oedema was found in 22 patients. The existence and extent of the periportal oedema were studied with regard to the injury type, sex, weight and age, heart frequency, arterial blood pressure, as well as the lactate, pH value, and base excess (BE) directly after the admission of the patient to the intensive care unit. RESULTS: There is a relevant statistical correlation between the existence of periportal oedema and the abdominal trauma (P<.0001), independent of the type of abdominal injury. No relevant correlation between periportal oedema and existence of liver rupture, liver haematoma, other abdominal organ injury, abdominal vessel injury, fracture in the skeletal system, or intracerebral bleeding was found. Periportal oedema occurs more commonly in females than in males, more in light weight patients than in the others, and more frequent in young patients than in older ones. There is no correlation with arterial blood pressure, heart rate, pH value, lactate, and BE. CONCLUSION: The existence of periportal oedema is one sign of abdominal trauma and is independent of liver injury. Although it correlates with the sex, weight, and age of the patient, there is no correlation with arterial blood pressure, heart rate, pH value, lactate, and BE.

Workflow analysis of laparoscopic Nissen fundoplication in infant pigs- a model for surgical feedback and training.

BACKGROUND: Many fields use workflow analysis to assess and improve performance of complex tasks. In pediatric endosurgery, workflow analysis may help optimize operative planning and motor skills by breaking down the procedure into particular phases, evaluating these steps individually, and supplying feedback to the surgeon. OBJECTIVE: To develop a module of computer-based surgical workflow analysis for laparoscopic Nissen fundoplication(LNF) and to evaluate its applicability in an infant pig model. METHODS: LNF was performed in 12 pigs (weight, 7-10 kg) by a single surgeon. Based on synchronized intra and extracorporal movie recordings, the surgical workflow was segmented into temporal operative phases(preparation, dissection, reconstruction and conclusion). During each stage, all actions were recorded in a virtual timeline using a customized workflow editor. Specific tasks, such as knot-tying, were evaluated in detail.Time necessary to perform these actions was compared throughout the study. RESULTS: While time required for the preparation decreased by more than 70% from 4577 to 1379 seconds,and the dissection phase decreased from 2359 to 399 seconds (pig 1 and 12, respectively), the other two phases remained relatively stable. Mean time to perform the entire suture and a 5-throw knot remained constant as well. CONCLUSION: Our workflow analysis model allows the quantitative evaluation of dynamic actions related to LNF.This data can be used to define average benchmark criteria for the procedures that comprise this operation. It thereby permits task-oriented refinement of surgical technique as well as monitoring the efficacy of training.Although preoperative preparation time decreased substantially, and dissection became faster, time required for the reconstruction and conclusion phases remained relatively constant for a surgeon with moderate experience.Likewise, knot-tying did not accelerate in this setting.S-117

[Inhaled nitric oxide for rescue treatment of refractory hypoxemia in ARDS patients]. / Inhaliertes Stickstoffmonoxid zur Behandlung refraktärer Hypoxämie bei ARDS-Patienten.

The acute respiratory distress syndrome (ARDS) is characterized by a maldistribution of pulmonary blood flow towards non-ventilated atelectatic lung areas being the main reason for intrapulmonary right-to-left shunt with the consequence of severe arterial hypoxemia. The application of inhaled nitric oxide (iNO) is a therapeutic option to selectively influence pulmonary blood flow in order to improve arterial oxygenation and to decrease pulmonary artery pressure without relevant systemic side effects. Although randomized controlled trials demonstrated no survival benefit in patient populations covering the entire severity range of acute lung injury, iNO represents a feasible rescue treatment for ARDS patients with severe refractory hypoxemia and is, therefore, an important option for ARDS therapy in specialized centers.

Cardia yield pressure measurement in an infant porcine model: a novel technique to evaluate the quality of laparoscopic fundoplication.

BACKGROUND: Cardia yield pressure (CYP) has been described as a measure of the combined effect of all antireflux mechanisms and not simply as another test of lower esophageal sphincter pressure. In this paper, we present a simple technique for the measurement of CYP before and after fundoplication through laparoscopic gastrostomy in an experimental pig model. MATERIALS AND METHODS: Twelve 8-week-old female pigs with a mean weight of 8.7 +/- 0.7 kg underwent laparoscopic gastrostomy placement and Nissen fundoplication under general anesthesia. CYP was determined before and after the fundoplication by filling the stomach with water until reaching the pressure at which the cardia opened and became incompetent. Pre- and postoperative CYP was compared by using the Student's t-test for paired samples. RESULTS: Laparoscopic Nissen fundoplication and gastrostomy was completed in all pigs. CYP increased in all subjects after fundoplication, from a mean of 20 +/- 8 to a mean of 63 +/- 13 cm of H(2)O (p < 0.001). The lowest increase in yield pressure of 17.5 cm was recorded after the first operation. Work-flow analysis revealed that this particular procedure took the longest, that bleeding from the liver was encountered, and shorter sutures than those used on all subsequent fundoplications may have compromised knot tying. CONCLUSIONS: CYP increases consistently after laparoscopic Nissen Fundoplication in young pigs. This parameter may be a good indicator of antireflux efficacy and functional quality of the result. Yield pressure measured through laparoscopic gastrostomy offers a new, feasible, and effective technique for the evaluation of antireflux surgery in an experimental setting. Moreover, this minimally invasive technique may become a simple investigative tool for other antireflux procedures.

The haemodynamic and catecholamine response to xenon/remifentanil anaesthesia in Beagle dogs.

The noble gas xenon seems to have minimal cardiovascular side-effects and so may be an ideal anaesthetic agent when investigating cardiovascular physiology. In comparison with standard modern anaesthetics, we investigated the haemodynamic and hormonal effects of xenon in Beagle dogs. After a 30 min baseline period, anaesthesia was induced with propofol and maintained with either (1) 1.2% isoflurane/70% nitrous oxide (N(2)O), (2) 0.8% isoflurane/0.5 microg/kg/min remifentanil or (3) 63% xenon/0.5 microg/kg/min remifentanil (n = 6 per group). Haemodynamics were recorded and blood samples taken before and 60 min after induction. Mean arterial blood pressure (MAP) was higher in conscious dogs than during isoflurane/N(2)O (86 +/- 2 vs. 65 +/- 2 mmHg, mean +/- SEM) and isoflurane/remifentanil anaesthesia (95 +/- 2 vs. 67 +/- 3 mmHg), whereas MAP did not decrease significantly in response to xenon/remifentanil anaesthesia (96 +/- 4 vs. 85 +/- 6 mmHg). Bradycardia was present during isoflurane/remifentanil (54 +/- 2/min) and xenon/remifentanil (40 +/- 3/min), but not during isoflurane/N(2)O anaesthesia (98 +/- 3/min, P < 0.05). Xenon/remifentanil anaesthesia induced the highest reduction in cardiac output (CO) (-61%), and the highest increase in systemic vascular resistance (+120%) among all treatment groups (P < 0.05). A simultaneous increase in endogenous adrenaline and noradrenaline concentrations could only be observed in the xenon/remifentanil group, whereas angiotensin II and vasopressin concentrations increased in all groups. In conclusion, xenon/remifentanil anaesthesia maintains MAP but reduces heart rate and CO and is associated with a considerable stimulation of vasopressor hormones in Beagle dogs. Therefore, xenon/remifentanil exerts a new quality of adverse haemodynamic effects different from volatile anaesthetics and may not perform better during studies of cardiovascular physiology.

Inhalation of the ETA receptor antagonist LU-135252 selectively attenuates hypoxic pulmonary vasoconstriction.

Endogenous endothelin (ET)-1 modulates hypoxic pulmonary vasoconstriction (HPV). Accordingly, intravenously applied ET(A) receptor antagonists reduce HPV, but this is accompanied by systemic vasodilation. We hypothesized that inhalation of an ET(A) receptor antagonist might act selectively on the pulmonary vasculature and investigated the effects of aerosolized LU-135252 in an experimental model of HPV. Sixteen piglets (weight: 25 +/- 1 kg) were anesthetized and mechanically ventilated at an inspiratory oxygen fraction (Fi(O(2))) of 0.3. After 1 h of hypoxia at Fi(O(2)) 0.15, animals were randomly assigned either to receive aerosolized LU-135252 as bolus (0.3 mg/kg for 20 min; n = 8, LU group), or to receive aerosolized saline (n = 8, controls). In all animals, hypoxia significantly increased mean pulmonary arterial pressure (32 +/- 1 vs. 23 +/- 1 mmHg; P < 0.01; means +/- SE) and increased arterial plasma ET-1 (0.52 +/- 0.04 vs. 0.37 +/- 0.05 fmol/ml; P < 0.01) compared with mild hyperoxia at Fi(O(2)) 0.3. Inhalation of LU-135252 induced a significant and sustained decrease in mean pulmonary arterial pressure compared with controls (LU group: 27 +/- 1 mmHg; controls: 32 +/- 1 mmHg; values at 4 h of hypoxia; P < 0.01). In parallel, mean systemic arterial pressure and cardiac output remained stable and were not significantly different from control values. Consequently, in our experimental model of HPV, the inhaled ET(A) receptor antagonist LU-135252 induced selective pulmonary vasodilation without adverse systemic hemodynamic effects.

[Therapeutic options for patients with acute lung injury]. / Akutes Lungenversagen--Therapeutische Optionen im Uberblick.

The treatment of acute lung injury is one of the most challenging tasks in intensive care medicine. Conventional therapeutic options cover lung protective mechanical ventilation with low tidal volumes and adequate PEEP, restrictive fluid management, prone positioning, and early recruitment maneuvers. These options should be used in parallel and should be accompanied by a suitable anti-infective therapy. In cases of refractory hypoxemia, inhaled nitric oxide offers in most patients a successful rescue option. In specialized centers the application of ECMO remains as a final ultima ratio.

[Initial management of polytraumatized patients in the emergency department]. / Schockraummanagement nach dem ATLS-Algorithmus.

Advanced Trauma Life Support (ATLS) provides a structured and efficient approach to the treatment of patients with multiple trauma in the emergency department. The performance of a well functioning interdisciplinary trauma team coordinated by an experienced trauma leader plays a pivotal role during the initial phase of patient care. The team's primary task is to establish and maintain stable vital signs by ensuring adequate oxygenation and fluid resuscitation while diagnostic or immediate life saving interventions and procedures are initiated. The following article describes the management of patients with multiple injuries in the emergency department based on the ATLS algorithm.

Low incidence of multiple organ failure after major trauma.

BACKGROUND: In major trauma patients, multiple organ failure (MOF) is considered a leading cause of death. Acute lung injury is deemed a "pacemaker" of MOF. The purpose of this study was to determine if incidence of organ failure and mortality in multiple trauma patients can be reduced by implementation of lung-protective strategies. METHODS: All critically ill multiple trauma patients admitted to the ICU of a major trauma center in Berlin, Germany from January 1999 to December 2002 were analyzed retrospectively. Patients were ventilated pressure controlled with low tidal volumes and adequate PEEP. RESULTS: n=287 patients were included. The most frequent injuries were traumatic brain injury (TBI-68%), chest trauma (68%), and lung contusions (55%). Injury severity score (ISS) was 32+/-19 (mean+/-standard deviation), polytraumaschluessel (PTS) 34+/-19, and APACHE II 14+/-7. During their ICU-stay 16 patients died, 9 (56%) from TBI. Single-organ-failure occurred in n=69 patients (24%, mortality 5%), two-organ-failure in n=22 (8%, mortality 14%), and MOF in n=9 (3%, mortality 13%); one patient died from MOF 14 days after trauma. The number of days on mechanical ventilation increased depending on the number of organs failed (R=0.618, p<0.001). Seven patients (2%) fulfilled ARDS criteria for longer than 24h despite optimized ventilatory settings, one died of irreversible shock. Patients with MOF had a significantly increased ICU-LOS (35+/-15 days) compared to patients without organ failure (11+/-11 days; p<0.001). CONCLUSION: The low incidence of MOF in our series of trauma patients suggests that MOF may be prevented in some patients by implementation of lung-protective strategies. The improved outcome was associated with an increased ICU-LOS.

Alteration of transthyretin microheterogeneity in serum of multiple trauma patients.

Transthyretin (TTR) which exists in various isoforms, is a valid marker for acute phase response and subclinical malnutrition. The aim of the study was to investigate the relationship between inflammation, oxidative stress and the occurrence of changes in microheterogeneity of TTR.A prospective, observational study at a level-I trauma center of a large urban medical university was performed. Patients were severely injured (n = 18; injury severity score (ISS): 34-66), and were observed within the first 24 hours of admittance and over the following days until day 20 after injury. 20 healthy subjects, matched by age and sex, were used as controls.TTR was enriched by immunoprecipitation. Microheterogeneity of TTR was determined by linear matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS). Four major mass signals were observed for TTR representing native, S-cysteinylated, S-cysteinglycinylated and S-glutathionylated TTR. In the course of their ICU stay, 14 of the 18 patients showed a transient change in microheterogeneity in favour of the S-cysteinglycinylated form of TTR (p < 0.05 vs. controls). The occurrence of this variant was not associated with the severity of trauma or the intensity of the acute-phase response, but was associated with oxidative stress as evidenced by Trolox.Our results demonstrate that changes in microheterogeneity of TTR occur in a substantial number of ICU trauma patients. The diagnostic values of these changes remains to be elucidated. It is speculated that TTR modification may well be the mechanism underlying the morphological manifestation of amyloidose or Alzheimer's diseases in patients surviving multiple trauma.

Endothelin-a receptor blockade does not debilitate the cardiovascular and hormonal adaptation to xenon or isoflurane anesthesia in dogs.

The objective of this study was to investigate whether circulatory and hormonal changes during xenon plus remifentanil or isoflurane plus remifentanil anesthesia are altered by endothelin-A (ET(A)) receptor blockade. Eight beagle dogs were studied in four protocols (n = 7 each). After a 30-min awake period, anesthesia was induced with 8 mg/kg propofol, administered intravenously (iv), and maintained with either 0.8% +/- 0.01% (vol/vol) isoflurane plus 0.5 microg/kg/min remifentanil (Protocol 1) or 63% +/- 1% (vol/vol) xenon plus 0.5 microg/kg/min remifentanil (Protocol 2) for 1 hr. Protocols 3 and 4 were preceded by ET(A) blockade with ABT-627 (Atrasentan; iv bolus of 1 mg/kg, then 100 microg/kg/h continuously). Irrespective of Atrasentan administration, the mean arterial blood pressure (MAP) ranged between 92 and 96 mm Hg in the awake state and fell to 67 +/- 3 mm Hg in controls (mean +/- SEM) and to 64 +/- 2 mm Hg in the Atrasentan group during isoflurane plus remifentanil anesthesia, whereas MAP remained constant during xenon plus remifentanil anesthesia. A decrease in heart rate was observed during either kind of anesthesia, but bradycardia was most prominent during xenon plus remifentanil anesthesia. In the control groups, and in the Atrasentan-treated dogs, a decrease in cardiac output and an increase in systemic vascular resistance were more prominent during xenon plus remifentanil than during isoflurane plus remifentanil anesthesia. Hormonal alterations during anesthesia remained unaffected by ET(A) receptor blockade. Angiotensin II and vasopressin increased in all protocols, and adrenaline and noradrenaline concentrations rose only during xenon plus remifentanil anesthesia. We conclude that the hemodynamic and hormonal adaptation after xenon plus remifentanil and isoflurane plus remifentanil anesthesia does not depend on the endothelin system, because it is unaffected by ET(A) receptor inhibition. Therefore, the use of Atrasentan does not impair cardiovascular stability during xenon- or isoflurane-based anesthesia in our dog model. However, the way anesthesia is performed is of crucial importance for hemodynamic and hormonal reactions observed during research in animals because the release of vasopressin and catecholamines may be intensified by xenon plus remifentanil anesthesia.

Low-dose inhalation of an endothelin-A receptor antagonist in experimental acute lung injury: ET-1 plasma concentration and pulmonary inflammation.

Inhalation of endothelin (ET)-A receptor antagonists has been shown to improve gas exchange in experimental acute lung injury (ALI) but may induce side effects by increasing circulating ET-1 levels. We investigated whether the inhaled ET(A) receptor antagonist, LU-135252, at low doses, improves gas exchange without affecting ET-1 plasma concentrations and lung injury in an animal model of ALI. Twenty-two piglets were examined in a prospective, randomized, controlled study. In anesthetized animals, ALI was induced by surfactant depletion. Animals received either LU-135252 at a dose of 0.3 mg/kg during 20 mins (LU group; n = 11), or nebulization of saline buffer (control group; n = 11). The Mann-Whitney U test was used to compare groups (P < 0.05). In the LU group, arterial partial pressure of oxygen (PaO2) and mean pulmonary artery pressure (MPAP) improved compared with the control group (PaO2, 319 +/- 44 mm Hg vs. 57 +/- 3 mm Hg; MPAP, 32 +/- 2 mm Hg vs. 41 +/- 2 mm Hg; values at 6 hrs after induction of ALI; P < 0.05). Mean arterial pressure and cardiac output were not different between groups. ET-1 plasma concentrations increased from 0.96 +/- 0.06 fmol/ml after induction of ALI to a maximum of 1.17 +/- 0.09 fmol/ml at 3 hrs after ALI onset in the LU group and did not differ significantly from the control group (1.21 +/- 0.08 fmol/ml, not significant). On histologic examination, we found no differences in total lung injury score between groups. However, the LU group revealed significantly reduced interstitial inflammation and hemorrhage (P < 0.05 vs. control group). In this animal model of ALI, inhalation of LU-135252 at a dose of 0.3 mg/kg induced a significant and sustained improvement in gas exchange, whereas there were no changes in ET-1 plasma concentrations. Furthermore, our data indicate a trend toward decreased pulmonary inflammation in the group receiving the inhaled ET(A) receptor antagonist.

Endothelin-1 influences the efficacy of inhaled nitric oxide in experimental acute lung injury.

Beneficial effects of inhaled nitric oxide (iNO) on arterial oxygenation in acute lung injury (ALI) suggest the presence of vasoconstriction in ventilated lung regions and this may be influenced by endothelin-1 (ET-1). We studied a possible interaction between ET-1 and iNO in experimental ALI. Sixteen piglets were anesthetized and mechanically ventilated (inspired O2 fraction, 1.0). After induction of ALI by surfactant depletion, animals were randomly assigned to either inhale 30 ppm NO (iNO group, n = 8), or to receive no further intervention (controls, n = 8). Measurements were performed during the following 4 hrs. In all animals, induction of ALI significantly decreased arterial oxygen tension (PaO2) from 569 +/- 15 (prelavage) to 58 +/- 3 mm Hg. Inhaled NO significantly increased PaO2 when compared with controls (iNO group: 265 +/- 51 mm Hg; controls: 50 +/- 4 mm Hg, values at 4 hrs, P < 0.01). Prelavage ET-1 plasma levels were comparable between groups (iNO: 0.74 +/- 0.03, controls: 0.71 +/- 0.03 fmol/ml, NS). During the protocol, the ET-1 levels increased and were different at 3 hrs (iNO: 0.93 +/- 0.06, controls: 1.25 +/- 0.09 fmol/ml; P < 0.05). PaO2 changes induced by iNO revealed a moderate and significant correlation with ET-1 plasma levels (R = 0.548, P = 0.001). Our data suggest that endogenous ET-1 production influences the efficacy of iNO in ALI. Furthermore, iNO reduced ET-1 plasma levels, possibly indicating anti-inflammatory properties of iNO in the early phase of ALI.

Inhalation of the endothelin-A receptor antagonist LU-135252 at various doses in experimental acute lung injury.

We studied the effects of the inhaled endothelin-A receptor antagonist LU-135252 at different doses on hemodynamics and gas exchange in an animal model of acute lung injury. Thirtysix piglets (27 +/- 1 kg) were anesthetized, mechanically ventilated (FiO2 1.0), and surfactant-depleted by repeated lung lavage. The animals were randomly assigned to receive either nebulized LU- 135252 for 30 minutes at a dose of 0.3 mg/kg (n = 12), or at a dose of 3.0 mg/kg (n = 12); n = 12 animals received no further treatment (Controls). Induction of acute lung injury decreased PaO2 from 566 +/- 8 mmHg to 53 +/- 2 mmHg (mean +/- SEM) and increased intrapulmonary shunt (QS/QT) from 13 +/- 1% to 57 +/- 2%. Inhalation of LU-135252 at either dose induced a significant and sustained increase in PaO2 (0.3 mg/kg: 349 +/- 39 mmHg; 3.0 mg/kg: 219 +/- 40 mmHg), and a significant decrease in QS/QT (0.3 mg/kg: 19 +/- 2%; 3.0 mg/kg: 27 +/- 3%) when compared with Controls (PaO2: 50 +/- 3 mmHg, QS/QT: 50 +/- 5%) (P < 0.05; values at 4 hours). Mean pulmonary artery pressure in LU-135252-treated animals (0.3 mg/kg: 31 +/- 2 mmHg; 3.0 mg/kg: 30 +/- 1 mmHg) was significantly lower than in Controls (40 +/- 2 mmHg), while there were no differences in mean arterial pressure and cardiac output. We conclude that inhalation of LU-135252 at either dose improved gas exchange and hemodynamics comparably, indicating that the lower dose was already sufficient to block the majority of endothelin-A receptors in ventilated regions of the injured lung.

Selective pulmonary vasodilation in acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is characterized by a marked maldistribution of pulmonary perfusion in favor of nonventilated, atelectatic areas of the lungs, and it is the main cause of pulmonary right-to-left shunting and hypoxemia. Therapeutic interventions to selectively influence pulmonary perfusion in ARDS became feasible with the introduction of inhaled nitric oxide, which provided a means not only to reduce pulmonary hypertension, but also to improve matching of ventilation to perfusion and, thus, hypoxemia. Clinical studies in ARDS subsequently demonstrated that the combination of inhaled nitric oxide with other interventions, such as positive end-expiratory pressure and prone positioning, yielded beneficial and additive effects on arterial oxygenation. Although the available randomized, controlled trials of this novel concept have so far failed to show an improved outcome in ARDS, inhaled nitric oxide is a clinically valuable option for the treatment of severe refractory hypoxemia in ARDS, and largely promoted the concept of selective pulmonary vasodilation in intensive care practice. Currently, aerosolization of various vasodilators, in particular prostaglandins, is under evaluation in models of acute lung injury and human ARDS. Ongoing research aims to augment the effectiveness of vasodilators with specific inhibitors of phosphodiesterases or by combination with intravenous vasoconstrictors. Consequently, several alternative ways to selectively modulate pulmonary vascular tone in patients with ARDS may be available in the near future. Cost-benefit analysis of these therapeutic options will largely determine their future perspective.