Pulmonary edema following intracranial hemorrhage

Focus on brain-lung crosstalk: Preventing or treating the pathological vicious circle between the brain and the lung

Recently, there has been increasing attention to bidirectional information exchange between the brain and lungs. Typical physiological data is communicated by channels like the circulation and sympathetic nervous system. However, communication between the brain and lungs can also occur in pathological conditions. Studies have shown that severe traumatic brain injury (TBI), cerebral hemorrhage, subarachnoid hemorrhage (SAH), and other brain diseases can lead to lung damage. Conversely, severe lung diseases such as acute respiratory distress syndrome (ARDS), pneumonia, and respiratory failure can exacerbate neuroinflammatory responses, aggravate brain damage, deteriorate neurological function, and result in poor prognosis. A brain or lung injury can have adverse effects on another organ through various pathways, including inflammation, immunity, oxidative stress, neurosecretory factors, microbiome and oxygen. Researchers have increasingly concentrated on possible links between the brain and lungs. However, there has been little attention given to how the interaction between the brain and lungs affects the development of brain or lung disorders, which can lead to clinical states that are susceptible to alterations and can directly affect treatment results. This review described the relationships between the brain and lung in both physiological and pathological conditions, detailing the various pathways of communication such as neurological, inflammatory, immunological, endocrine, and microbiological pathways. Meanwhile, this review provides a comprehensive summary of both pharmacological and non-pharmacological interventions for diseases related to the brain and lungs. It aims to support clinical endeavors in preventing and treating such ailments and serve as a reference for the development of relevant medications.

[A case of neurogenic pulmonary edema due to left internal carotid artery occlusion]

A 79-year-old woman developed consciousness disturbance, left eye deviation, right hemiplegia and aphasia with hypoxemia. Chest X-ray showed bilateral pulmonary edema. MRI revealed the left internal carotid artery occlusion and entire left middle cerebral artery infarct including insular cortex. We performed mechanical thrombectomy therapy and TICI3 recanalization was obtained. During operation, the respiratory condition deteriorated and the ventilator was started after mechanical thrombectomy therapy. Chest X-ray showed butterfly shadow, which indicated pulmonary edema. Pulmonary edema improved on the 2nd day of onset, and disappeared on the 3rd day. There was no heart diseases such as Takotsubo myocardiopathy, acute cardiac failure and cardiomyopathy on echocardiography and electrocardiography. Therefore, we diagnosed her as having neurogenic pulmonary edema due to cerebral infarction including insular cortex. We consider that left insular cortex infarction was a trigger of neurogenic pulmonary edema. If hypoxemia associated with infarction including the insular cortex, neurogenic pulmonary edema should be considered for medical treatment.

Mild Traumatic Brain Injury in Mice Beneficially Alters Lung NK1R and Structural Protein Expression to Enhance Survival after Pseudomonas aeruginosa Infection

Mild traumatic brain injury (mTBI) in a murine model increases survival to a bacterial pulmonary challenge compared with blunt tail trauma (TT). We hypothesize substance P and its receptor, the neurokinin 1 receptor (NK1R; official name TACR1), play a role in the increased survival of mTBI mice. Mice were subjected to mTBI or TT, and 48 hours after trauma, the levels of NK1R mRNA and protein were significantly up-regulated in mTBI lungs. Examination of the lung 48 hours after injury by microarray showed significant differences in the expression of 433 gene sets between groups, most notably genes related to intercellular proteins. Despite down-regulated gene expression of connective proteins, the presence of an intact pulmonary vasculature was supported by normal histology and bronchoalveolar lavage protein levels. To determine whether these mTBI-induced lung changes benefited in vivo responses, two chemotactic stimuli (a CXCL1 chemokine and a live Pseudomonas aeruginosa infection) were administered 48 hours after trauma. For both stimuli, mTBI mice recruited more neutrophils to the lung 4 hours after instillation (CXCL1: mTBI = 6.3 ± 1.3 versus TT = 3.3 ± 0.7 neutrophils/mL; Pseudomonas aeruginosa: mTBI = 9.4 ± 1.4 versus TT = 5.3 ± 1.1 neutrophils/mL). This study demonstrates that the downstream consequences of mTBI on lung NK1R levels and connective protein expression enhance neutrophil recruitment to a stimulus that may contribute to increased survival.

Neurogenic Pulmonary Edema Following Catastrophic Subarachnoid Hemorrhage: A Case Report and Pathophysiologic Review

Neurogenic pulmonary edema (NPE) is an increase in interstitial and alveolar lung fluid that occurs as a direct consequence of acute or subacute central nervous system (CNS) injury. In this review we describe a patient who developed hypoxemic respiratory failure as a result of NPE following catastrophic subarachnoid hemorrhage (SAH). The patient displayed many of the characteristic symptoms, signs, and physiologic aberrations associated with NPE, including an altered level of consciousness, dyspnea, cyanosis, crackles, hypoxemia, and diffuse pulmonary infiltrates. These clinical features can be mistaken for other causes of pulmonary edema and may lead to confusion in the diagnosis and therapeutic approach of hypoxemic respiratory failure in the setting of CNS injury. Although NPE is thought to be due to a combination of pulmonary capillary leakage and elevated intravascular pressures, many questions about its pathophysiology remain unanswered. Data from animal models using therapeutic trials of antiadrenergic agents suggest a significant role for sympathetic nervous system activation and massive catecholamine release in the pathogenesis of this disorder. The most common causes of NPE include head trauma, seizures, cerebral hemorrhages, subarachnoid bleeds, and increased intracranial pressure of any etiology. As is generally observed with this disorder, conservative and supportive management of our patient's respiratory failure led to complete resolution of the NPE within 96 hours. Although NPE is an infrequent phenomenon, it should be considered in the differential diagnosis of all patients who develop respiratory complications soon after CNS injury.

Early coagulation events induce acute lung injury in a rat model of blunt traumatic brain injury

Acute lung injury (ALI) and systemic coagulopathy are serious complications of traumatic brain injury (TBI) that frequently lead to poor clinical outcomes. Although the release of tissue factor (TF), a potent initiator of the extrinsic pathway of coagulation, from the injured brain is thought to play a key role in coagulopathy after TBI, its function in ALI following TBI remains unclear. In this study, we investigated whether the systemic appearance of TF correlated with the ensuing coagulopathy that follows TBI in ALI using an anesthetized rat blunt trauma TBI model. Blood and lung samples were obtained after TBI. Compared with controls, pulmonary edema and increased pulmonary permeability were observed as early as 5 min after TBI without evidence of norepinephrine involvement. Systemic TF increased at 5 min and then diminished 60 min after TBI. Lung injury and alveolar hemorrhaging were also observed as early as 5 min after TBI. A biphasic elevation of TF was observed in the lungs after TBI, and TF-positive microparticles (MPs) were detected in the alveolar spaces. Fibrin(ogen) deposition was also observed in the lungs within 60 min after TBI. Additionally, preadministration of a direct thrombin inhibitor, Refludan, attenuated lung injuries, thus implicating thrombin as a direct participant in ALI after TBI. The results from this study demonstrated that enhanced systemic TF may be an initiator of coagulation activation that contributes to ALI after TBI.

Extracorporeal membrane oxygenation for acute life-threatening neurogenic pulmonary edema following rupture of an intracranial aneurysm

Neurogenic pulmonary edema (NPE) leading to cardiopulmonary dysfunction is a potentially life-threatening complication in patients with central nervous system lesions. This case report describes a 28-yr woman with life-threatening fulminant NPE, which was refractory to conventional respiratory treatment, following the rupture of an aneurysm. She was treated successfully with extracorporeal membrane oxygenation (ECMO), although ECMO therapy is generally contraindicated in neurological injuries such as brain trauma and diseases that are likely to require surgical intervention. The success of this treatment suggests that ECMO therapy should not be withheld from patients with life-threatening fulminant NPE after subarachnoid hemorrhage.

Neisseria sicca endocarditis requiring mitral valve replacement in a previously healthy adolescent

Infective endocarditis due to Neisseria sicca, a normal inhabitant of the upper respiratory tract, is rarely reported but associated with embolic phenomena and large vegetations often requiring surgical intervention. We report a previously healthy 12-year-old girl who presented with prolonged fever and altered mental status. The patient developed rapidly progressive respiratory insufficiency and cardiovascular instability, and echocardiography demonstrated a large vegetation on the mitral valve. She developed worsening mitral regurgitation with resultant pulmonary hemorrhage and underwent mitral valve replacement. Her blood culture was positive for N. sicca. This infection should be considered in patients with prolonged high fever and multiorgan dysfunction. Despite a typically severe course, reported mortality is low.

Determining the aetiology of pulmonary oedema by the oedema fluid-to-plasma protein ratio

We hypothesised that the oedema fluid-to-plasma protein (EF/PL) ratio, a noninvasive measure of alveolar capillary membrane permeability, can accurately determine the aetiology of acute pulmonary oedema. 390 mechanically ventilated patients with acute pulmonary oedema were enrolled. A clinical diagnosis of acute lung injury (ALI), cardiogenic pulmonary oedema or a mixed aetiology was based on expert medical record review at the end of hospitalisation. The EF/PL ratio was measured from pulmonary oedema fluid and plasma samples collected at intubation. 209 patients had a clinical diagnosis of ALI, 147 had a diagnosis of cardiogenic pulmonary oedema and 34 had a mixed aetiology. The EF/PL ratio had an area under the receiver-operating curve of 0.84 for differentiating ALI from cardiogenic pulmonary oedema. Using a predefined cut-off of 0.65, the EF/PL ratio had a sensitivity of 81% and a specificity of 81% for the diagnosis of ALI. An EF/PL ratio >/=0.65 was also associated with significantly higher mortality and fewer ventilator-free days. Noninvasive measurement of the EF/PL ratio is a safe and reliable bedside method for rapidly determining the aetiology of acute pulmonary oedema that can be used at the bedside in both developed and developing countries.

Cardiac troponin I and acute lung injury after subarachnoid hemorrhage

INTRODUCTION

There are few predictors of acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS) after subarachnoid hemorrhage (SAH). We hypothesized that cardiac troponin I, which is associated with cardiovascular morbidity, would also predict ALI.

METHODS

We prospectively enrolled 171 consecutive patients with SAH. Troponin was routinely measured on admission and the next day and subsequently if abnormal. We prospectively recorded the maximum troponin, in-hospital events, and clinical endpoints. ALI and ARDS were defined by standard criteria.

RESULTS

Acute lung injury was found in 10 patients (6%), ARDS in an additional 14 (8%), and pulmonary edema without lung injury in 9 (5%). Maximum troponin was different in patients without lung injury or pulmonary edema (0.03 [0.02-0.12] mcg/l), ALI (0.17 [0.04-1.4]), or ARDS (0.31 [0.9-1.8], P < 0.001). In ROC analysis, a cutoff of 0.04 mcg/l had 91% sensitivity and 42% specificity for ALI or ARDS (AUC = 0.75, P < 0.001). Troponin was associated with ALI or ARDS after accounting for neurologic grade in multivariate models without further contribution from pneumonia, packed red cell transfusion, gender, tobacco use, coronary artery disease, vasospasm, depressed ejection fraction on echocardiography, or CT grade. Lung injury was associated with worse functional outcome at 14 days, but not at 28 days or 3 months.

CONCLUSION

Troponin I is associated with the development of ALI after SAH.

Neurogenic pulmonary edema in patients with subarachnoid hemorrhage

Neurogenic pulmonary edema (NPE), leading to cardiopulmonary dysfunction, is a potentially life-threatening complication in patients with aneurysmal subarachnoid hemorrhage (SAH). We sought to assess the clinical presentation and risk factors for the development of NPE after SAH. The database contained prospectively collected information on 477 patients with SAH. Baseline characteristics, clinical and radiologic severity of the bleeding, localization of the ruptured aneurysm, and clinical outcome of patients with NPE were compared with those of patients without NPE. Further, in patients with NPE, intracranial pressure, serum cardiac biomarkers, and hemodynamic parameters during the acute phase were evaluated retrospectively. The incidence of NPE was 8% (39 of 477 patients). Most patients with NPE were severely impaired and all of them presented with radiologically severe hemorrhage. The incidence of NPE was significantly higher in patients with ruptured aneurysm in the posterior circulation. Elevated intracranial pressure was found in 67%, pathologically high cardiac biomarkers in up to 83% of patients with NPE. However, no patient suffered from persistent cardiac dysfunction. Compared with patients without NPE, patients with NPE showed poor neurologic outcome (Glasgow outcome scale 1 to 3 in 25% vs.77% of patients). In conclusion, patients with NPE have a high mortality rate more likely due to their severity grade of the bleeding. Morbidity and mortality due to cardiopulmonary failure might be reduced by appropriate recognition and treatment. The awareness of and knowledge about occurrence, clinical presentation, and treatment of NPE, are essential for all those potentially confronted with patients with SAH in the acute phase.

Early embolization for ruptured aneurysm in acute stage of subarachnoid hemorrhage with neurogenic pulmonary edema

SUMMARY

Four cases of ruptured aneurysmal subarachnoid hemorrhage (SAH) presented with severe neurogenic pulmonary edema (NPE). On admission, two patients were grade IV and two were grade V according to Hunt and Hess grading. All patients needed respiratory management with the assistance of a ventilator. Three of them underwent endovascular treatment for the ruptured aneurysms within three days from onset after ensuring hemodynamic stability. Immediately after the endovascular treatment, lumbar spinal drainage was inserted in all the patients. The pulmonary edema findings disappeared rapidly after the respiratory management. The results were good recovery in two, and moderate disability in two. We concluded that early embolization of ruptured aneurysm and placement of spinal drainage is a satisfactory option for severe SAH with NPE.

Neurogenic Pulmonary Edema Due to Traumatic Brain Injury: Evidence of Cardiac Dysfunction

• Background Acute neurogenic pulmonary edema, a common and underdiagnosed clinical entity, can occur after virtually any form of injury of the central nervous system and is a potential early contributor to pulmonary dysfunction in patients with head injuries.

• Objective To explore myocardial function in patients with evident neurogenic pulmonary edema after traumatic head injury.

• Methods During a 1-year period in a university hospital in Sfax, Tunisia, information was collected prospectively on patients admitted to the 22-bed intensive care unit because of isolated traumatic head injury who had neurogenic pulmonary edema. Data included demographic information, vital signs, neurological status, physiological status, and laboratory findings. All of the patients had computed tomography and plain radiography of the neck and determination of cardiac function.

• Results All 7 patients in the sample had cardiac dysfunction. Evidence of myocardial damage was confirmed by echocardiography in 3 patients, pulmonary artery catheterization in 3 patients, and/or postmortem myocardial biopsy in 4 patients. Echocardiography studies, repeated 7 days after the initial study in one patient and 90 days afterward in another, showed complete improvement in wall motion, with a left ventricular ejection fraction of 0.65.

• Conclusion All patients who had neurogenic pulmonary edema due to traumatic head injury had myocardial dysfunction. The mechanisms of the dysfunction were multiple. The great improvement in wall motion seen in 2 patients indicated the presence of a stunned myocardium. Further studies are needed to understand the mechanisms of this cardiac dysfunction.

Pulmonary edema and cardiac dysfunction following subarachnoid hemorrhage

BACKGROUND

Pulmonary edema (PE) can occur in the early or late period following subarachnoid hemorrhage (SAH). The incidence of each type of PE is unknown and the association with ventricular dysfunction, both systolic and diastolic, has not been described.

METHODS

Retrospective chart review of 178 consecutive patients with SAH surgically treated over a three-year period. Patients with pulmonary edema diagnosed by a radiologist were included. Early onset SAH was defined as occurring within 12 hours. Cardiac function at the time of the PE was analyzed using hemodynamic and echocardiographic criteria of systolic and diastolic dysfunction. Pulmonary edema was observed in 42 patients (28.8%) and was more often delayed (89.4%). Evidence of cardiac involvement during PE varied between 40 to 100%.

RESULTS AND CONCLUSIONS

Pulmonary edema occurs in 28.8% of patients after SAH, and is most commonly delayed. Cardiac dysfunction, both systolic and diastolic, is commonly observed during SAH and could contribute to the genesis of PE after SAH.

Pulmonary Complications of Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

Pulmonary complications challenge the medical management of patients who have sustained aneurysmal subarachnoid hemorrhage (SAH). We assessed the frequency and types of pulmonary complications after aneurysmal SAH and analyzed the impact of pulmonary complications on patient outcome.

METHODS

We reviewed the records of all patients with acute SAH treated at our institution between 1990 and 1997. Three hundred five consecutive patients with an aneurysmal hemorrhage source documented by angiography and treated within 7 days of ictus were analyzed. Outcomes at longest follow-up (mean, 16 mo) were measured by use of the Glasgow Outcome Scale.

RESULTS

Pulmonary complications were documented in 66 patients (22%). The pulmonary complications were nosocomial pneumonia in 26 patients (9%), congestive heart failure in 23 (8%), aspiration pneumonia in 17 (6%), neurogenic pulmonary edema in 5 (2%), pulmonary embolus in 2 (&lt;1%), and other pulmonary disorders in 4 (1%); 11 patients had two pulmonary complications. The incidence of symptomatic vasospasm was greater in patients with pulmonary complications (63%) than in patients without pulmonary complications (31%) (P= 0.001), and this association was independent of age and clinical grade at admission (odds ratio, 3.68; P&lt; 0.001). Overall clinical outcomes were worse in patients with pulmonary complications (mean Glasgow Outcome Scale score, 3.3) than in patients without pulmonary complications (mean Glasgow Outcome Scale score, 4.0; P= 0.0001), but pulmonary complications were not an independent predictor of worse outcome when adjusted for age and clinical grade at admission (odds ratio, 1.38; P= 0.315).

CONCLUSION

Patients who experience pulmonary complications after aneurysmal SAH have a higher incidence of symptomatic vasospasm than do patients without pulmonary complications. This most likely reflects both the failure to maintain aggressive hypervolemic and hyperdynamic therapy in patients with pulmonary compromise and the possible precipitation of congestive heart failure by hypervolemic therapy in patients with preexisting delayed ischemic neurological deficit. Although patients with pulmonary complications have worse overall clinical outcomes than do patients without pulmonary complications, this is attributable to older age and worse clinical grades at admission.

Protein transport across the lung epithelial barrier

Alveolar lining fluid normally contains proteins of important physiological, antioxidant, and mucosal defense functions [such as albumin, immunoglobulin G (IgG), secretory IgA, transferrin, and ceruloplasmin]. Because concentrations of plasma proteins in alveolar fluid can increase in injured lungs (such as with permeability edema and inflammation), understanding how alveolar epithelium handles protein transport is needed to develop therapeutic measures to restore alveolar homeostasis. This review provides an update on recent findings on protein transport across the alveolar epithelial barrier. The use of primary cultured rat alveolar epithelial cell monolayers (that exhibit phenotypic and morphological traits of in vivo alveolar epithelial type I cells) has shown that albumin and IgG are absorbed via saturable processes at rates greater than those predicted by passive diffusional mechanisms. In contrast, secretory component, the extracellular portion of the polymeric immunoglobulin receptor, is secreted into alveolar fluid. Transcytosis involving caveolae and clathrin-coated pits is likely the main route of alveolar epithelial protein transport, although relative contributions of these internalization steps to overall protein handling of alveolar epithelium remain to be determined. The specific pathways and regulatory mechanisms responsible for translocation of proteins across lung alveolar epithelium and regulation of the cognate receptors (e.g., 60-kDa albumin binding protein and IgG binding FcRn) expressed in alveolar epithelium need to be elucidated.

Cardiopulmonary manifestations of fulminant enterovirus 71 infection

BACKGROUND

The pathogenesis of acute pulmonary edema and cardiac collapse after enterovirus 71 (EV71) infection are not completely understood.

OBJECTIVE

To determine the hemodynamic features and the mechanism of pulmonary edema (PE) after EV71 infection by direct intracardiac monitoring.

DESIGN

Prospective clinical and laboratory study at a tertiary medical center.

PARTICIPANTS

Five consecutive infants, ages 2 to 13 months, with EV71 infection-proved by viral isolation in 4 and antibody in 1-with PE were enrolled. The clinical characteristics were systemically assessed. Hemodynamic profiles were determined every 4 hours by simultaneously implanted pulmonary arterial and central venous catheters during the acute stage.

RESULTS

Magnetic resonance imaging revealed that all 5 infants had brainstem lesions. All patients had tachycardia and hyperthermia. Transient systolic hypertension was noted in 1 patient, and 1 presented with hypotension. Pulmonary artery pressure in all 5 infants was normal or mildly elevated (26-31 mm Hg), and central venous pressure ranged from 10 to 22 mm Hg. Pulmonary artery occlusion pressures were normal or slightly elevated (13-16 mm Hg). Systemic and pulmonary vascular resistances were transiently increased in only 1 patient. The stroke volume index decreased to 15.3 to 35.7 mL/M2 (normal: 30-60 mL/M2), but because of the elevated heart rate, the cardiac index did not decrease. All hemodynamics normalized within days.

CONCLUSION

Fulminant EV71 infection may lead to severe neurologic complications and acute PE. The acute PE and cardiopulmonary decompensation in EV71 infection are not directly caused by viral myocarditis. The mechanism of PE may be related to increased pulmonary vascular permeability caused by brainstem lesions and/or systemic inflammatory response instead of increased pulmonary capillary hydrostatic pressure.

Pulmonary edema associated with child abuse: case reports and review of the literature

Pulmonary edema has been an unreported finding in the evaluation of abused children. We describe 2 cases of pulmonary edema in abused infants, 1 after confessed suffocation and the other after inflicted head injury. A review of the literature regarding postobstructive and neurogenic pulmonary edema suggests useful inferences for the forensic evaluation of maltreated children who present with this finding.

General pediatric emergencies. Acute pulmonary edema

This article focuses on three types of acute pulmonary edema in children: negative-pressure pulmonary edema, neurogenic pulmonary edema, and cardiogenic pulmonary edema.

Continuous pulse oximetry in acute hemiparetic stroke

BACKGROUND AND PURPOSE

Hypoxemia can adversely affect ischemic brain tissue in laboratory animals. The aim of this study was to assess the value of early continuous monitoring with pulse oximetry in detecting arterial oxygen desaturations in patients with acute hemiparetic stroke, and the effects of oxygen administration.

METHODS

Over a period of 6 months 49 consecutive patients with acute hemiparetic stroke of </=12 h duration were monitored for the first 48 h with pulse oximetry. Patients in whom arterial oxygen saturation (SaO(2)) fell beneath 96% for a period longer than 5 min were treated with oxygen administered via nasal prongs or oxygen mask.

RESULTS

Thirty-one patients (63.3%) developed arterial oxygen desaturations. Of these patients 28 could effectively be treated with oxygen up to a flow-rate of 5 l/min. Only 3 patients required higher oxygen concentrations from 6 to 10 l/min. No acute adverse effects of oxygen treatment were observed. All patients with a history of cardiac and pulmonary disease developed drops in SaO(2). The occurrence of arterial oxygen desaturations was related to stroke severity (P=0.024), the presence of dysphagia (P=0.047), and older age (P=0.037).

CONCLUSION

Patients with acute hemiparetic stroke frequently develop arterial oxygen desaturations. Continuous monitoring with pulse oximetry in this group of patients is a simple and useful method to detect drops in SaO(2) and to titrate oxygen administration.

Pulmonary edema after resection of a fourth ventricle tumor: possible evidence for a medulla-mediated mechanism

A well-recognized fact is that some patients may have development of pulmonary edema in association with disorders of the central nervous system. The origin of this phenomenon, known as neurogenic pulmonary edema, is unclear but may result, in part, from select pulmonary venoconstriction modulated by autonomic outflow from the medulla oblongata. We describe a 21-year-old man who had development of pulmonary edema in association with surgical resection of a brain tumor that was close to the medulla. Other than the possibility of medullary dysfunction, which could have occurred after surgical manipulation, no other risk factor for pulmonary edema was identified. Of note, the patient's blood pressure remained normal throughout the perioperative period, and no fluid overload or primary cardiac dysfunction was evident. This case supports the theory that the medulla is an important anatomic site of origin for neurogenic pulmonary edema and that alterations in medullary function can induce pulmonary edema in humans, independent of systemic hypertension.

Alveolar epithelial fluid transport capacity in reperfusion lung injury after lung transplantation

Reperfusion lung injury is an important cause of morbidity and mortality after orthotopic lung transplantation. The purpose of this study was to investigate the function of the alveolar epithelium in the setting of reperfusion lung injury. Simultaneous samples of pulmonary edema fluid and plasma were collected from eight patients with severe post-transplantation reperfusion edema. The edema fluid to plasma protein ratio was measured, an indicator of alveolar-capillary barrier permeability. The initial edema fluid to plasma protein ratio was > 0.75 in six of eight patients, confirming the presence of increased permeability of the alveolar-capillary barrier. Graft ischemic time was positively correlated with the degree of permeability (r = 0.77, p < 0.05). In four of six patients with serial samples, there was a high rate of alveolar fluid clearance (19 +/- 9%/h, mean +/- SD). Alveolar fluid clearance was calculated from serial samples in six patients. Intact alveolar fluid clearance correlated with less histologic injury, rapid resolution of hypoxemia, and more rapid resolution of radiographic infiltrates. The two patients with no net alveolar fluid clearance had persistent hypoxemia and more severe histologic injury. This study provides the first direct evidence that increased permeability to protein is the usual cause of reperfusion edema after lung transplantation, with longer ischemic times associated with greater permeability to protein in the transplanted lung. The high rates of alveolar fluid clearance indicate that the fluid transport capacity of the alveolar epithelium may be well preserved in the allograft despite reperfusion lung injury. The ability to reabsorb fluid from the alveolar space was a marker of less severe reperfusion injury, whereas the degree of alveolar-capillary barrier permeability to protein was not. Measurement of alveolar fluid clearance may be useful to assess the severity of reperfusion lung injury and to predict outcome when pulmonary edema develops after lung transplantation.

Neurogenic pulmonary oedema

Neurogenic pulmonary oedema is a relatively rare but significant complication of head injury. A case is described and the presentation, pathophysiology, and management are discussed.

Evidence for a hydrostatic mechanism in human neurogenic pulmonary edema

STUDY OBJECTIVES

To identify the relative contribution of hydrostatic and permeability mechanisms to the development of human neurogenic pulmonary edema.

DESIGN

Retrospective review of patients with neurogenic pulmonary edema who had pulmonary edema fluid analysis.

SETTING

University hospital ICU.

PATIENTS

Twelve patients with neurogenic pulmonary edema in whom the associated neurologic condition was subarachnoid hemorrhage (n = 8, 67%), postcraniotomy (n = 2), and stroke (n = 2).

MEASUREMENTS

Protein concentration was measured from pulmonary edema fluid and plasma samples obtained shortly after the onset of clinical pulmonary edema.

RESULTS

The mechanism of pulmonary edema was classified according to the initial alveolar edema fluid to plasma protein concentration ratio. A hydrostatic mechanism (ratio < or = 0.65) was observed in seven patients, none of whom had cardiac failure or intravascular volume overload. Five patients had evidence for increased permeability (ratio > 0.70). Patients with a hydrostatic mechanism had better initial oxygenation (mean +/- SD PaO2/FIO2 [fraction of inspired oxygen] = 233 +/- 132) compared with patients with increased permeability (PaO2/FIo2 = 80 +/- 42), and oxygenation improved more rapidly in the hydrostatic patients. Overall mortality (58%) was high, but it was related to unresolved neurologic deficits, not to respiratory failure.

CONCLUSION

Many of our patients had a hydrostatic mechanism for neurogenic pulmonary edema. This is a novel observation in humans since prior clinical case reports have emphasized increased permeability as the usual mechanism for neurogenic pulmonary edema. These findings are consistent with pulmonary venoconstriction or transient elevation in left-sided cardiovascular pressures as contributing causes to the development of human neurogenic pulmonary edema.

Acute lung injury in isolated traumatic brain injury

OBJECTIVE

To determine the incidence of acute lung injury (ALI) in comatose patients after isolated traumatic brain injury, to determine whether specific brain lesions diagnosed by cranial computed tomographic scans are associated with ALI, and to determine the outcome of patients with head injuries who developed ALI.

METHODS

Descriptive epidemiology and a case-control study using the Traumatic Coma Data Bank was performed to evaluate clinical features and brain lesions associated with ALI in patients with isolated head trauma. Patients with ALI were defined as those who demonstrated a ratio of partial pressure of arterial oxygen to fractional expired oxygen of 300 or less.

RESULTS

Twenty of 100 comatose patients developed ALI. Patients with ALI were almost three times more likely to die or survive in a vegetative state (odds ratio, 2.8; 95% confidence interval, 1.6-4.9). Specific anatomic brain lesions diagnosed by cranial computed tomographic scans were not associated with ALI. However, patients with more severe injuries, i.e., large nonevacuated mass lesions, and those with midline shift demonstrated a 10- and 5-fold increased risk of ALI (odds ratio, 9.9; 95% confidence interval, 1.2-217.1; and odds ratio, 5.5; 95% confidence interval, 1.5-20.0).

CONCLUSIONS

ALI was common in comatose victims with an isolated traumatic brain injury and was associated with an increased risk of death or a severe neurological morbidity. ALI was associated with the global severity of head injury but not with specific anatomic lesions diagnosed by cranial computed tomographic scans.

Haemodynamic changes in neurogenic pulmonary oedema: effect of dobutamine

The haemodynamic and gas exchange abnormalities occurring in neurogenic pulmonary oedema (NPO) were examined retrospectively in 20 patients admitted to the Intensive Therapy Unit (ITU) over a 45-month period (February 1992 to November 1995). In 12 patients, where vasoactive therapy with dobutamine was employed, its effect on haemodynamics was examined. Cardiac index (CI median 2.2 l min-1 m-2) and left ventricular stroke work index (LVSWI 20 g.m.m-2) were markedly depressed, while pulmonary artery wedge pressure (PAWP 17 mmHg), mean pulmonary artery pressure (MPAP 30.5 mmHg), systemic vascular resistance index (SVRI 2852 dyne.s.cm-5.m2) and pulmonary vascular resistance index (PVRI 393 dyne.s.cm-5.m2) were substantially elevated above normal values. Mean arterial pressure (MAP 82.5 mmHg) and heart rate (HR 102 bpm) were within normal limits. The poor oxygenation is indicated by a median PaO2/fiO2 ratio of 18.0 kPa. Patients treated with dobutamine showed significant increases in CI and LVSWI and significant falls in SVRI and PAWP at 2 and 6 h after institution of therapy, and there was a significant rise in PaO2/fiO2 ratio to 27.8 kPa at 6 h. NPO was generally associated with severe depression of myocardial function and elevation of pulmonary vascular pressures. This dysfunction was readily reversed by dobutamine.

The etiology of pulmonary edema in fresh water near-drowning

Drowning is a significant cause of death in children and young adults. It is thought to result from the inhalation of either fresh or sea water resulting in lung damage and ventilation-perfusion mismatching. The clinical course, chest roentgenographs, serum electrolytes, alveolar-arterial oxygen gradient, and complete blood count of 10 fresh water drowning victims with pulmonary edema were recorded. Six responded dramatically clinically and radiographically within 24 hours, and most did not have significant alterations of their serum electrolyte levels, especially serum chloride. On the basis of the rapid clearing of the pulmonary edema and the lack of evidence of significant fluid aspiration, neurogenic pulmonary edema is postulated to have played a role in the development of the pulmonary edema in these patients.

Neurogenic pulmonary edema in fatal and nonfatal head injuries

Impaired pulmonary function is a frequent but poorly understood complication of acute head injury (HI). A potential early contributor to the pulmonary dysfunction seen in HI patients is neurogenic pulmonary edema (NPE). We hypothesized that NPE would occur early after HI and that it would have a continuum of clinical severity depending on the severity of the HI and associated intracranial hypertension. A large autopsy data base and inpatient HI data base were used to search for cases of NPE. Patients in the autopsy data base were stratified according to injury type and whether they died at the scene or within 96 hours of injury. There were significant (p < 0.0001, analysis of variance) elevations in lung weights in patients dying at the scene and within 96 hours from HI, compared with those dying from other noncentral nervous system injuries. No other organs studied showed significant weight increases. The incidence of NPE in isolated HI patients dying at the scene was 32%. In patients with isolated HI dying within 96 hours, the incidence of NPE was 50%. We found an inverse correlation (r = 0.62; p < 0.0014) between the initial cerebral perfusion pressure and the PaO2/FIO2 ratio despite a normal-appearing chest x-ray film. We conclude that NPE occurs frequently in HI patients. The process of edema formation begins early in the clinical course and is isolated to the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

No effects of large doses of catecholamines on vascular permeability in isolated blood-perfused dog lungs

Neurogenic pulmonary oedema (NPO) is believed to be induced by intense activation of the sympathetic nervous system, characterized by massive secretion of catecholamines into the blood stream. There is a possibility that NPO is partly the result of increased vascular permeability. However, the mechanism for an increase in pulmonary vascular permeability is not known. The present study was designed to test the hypothesis that large doses of catecholamines increase pulmonary microvascular permeability directly. Adrenaline or noradrenaline (100 and 300 micrograms) was injected as a bolus into isolated dog lungs perfused with heparinized autologous blood at constant pressure. Adrenaline or noradrenaline produced sustained lung weight loss although both catecholamines increased pulmonary capillary pressure, assessed by double occlusion pressure, by 2-5 mmHG above baseline. Vascular permeability, as measured by the capillary filtration coefficient and the isogravimetric capillary pressure, did not change significantly from baseline at 30 and 60 min after catecholamine. Finally, the final-to-initial wet lung weight ratio of the catecholamine-treated lungs did not differ from that of saline-injected control lungs. Thus, we conclude that circulating catecholamines, even at supraphysiological doses, do not increase permeability in isolated blood-perfused dog lungs.

[Acute neurogenic pulmonary edema: a case report]

The authors report a case of acute neurogenic pulmonary edema in a 28-year-old woman who presented rupture of an internal carotid artery aneurysm and subarachnoid hemorrhage. The respiratory disorders started at the same time the patient's symptomatology aggravated. Some etiological and pathophysiological aspects on neurogenic pulmonary edema are revised.

Profound pulmonary shunting without edema following stereotaxic biopsy of hypothalamic germinoma. Case report

Hypoxemia is a nearly constant accompaniment of head injury. Diverse theories have been proposed to explain this relationship. The authors report the case of a patient who suffered an episode of severe, transient, arterial oxygen desaturation during "controlled" brain trauma: an otherwise uneventful stereotaxic biopsy of a small germinoma of the hypothalamus. Evidence is provided that pure ventilation-perfusion mismatching, without pulmonary edema, underlay the hypoxemia. The hypothalamus is intimately involved in matching pulmonary ventilation to perfusion; the hypoxemia of various brain injuries may be mediated by perturbation of this structure.

Medulla oblongata edema associated with neurogenic pulmonary edema. Case report

Neurogenic pulmonary edema (NPE) occurs in association with central nervous system disease without underlying cardiopulmonary problems. It is characterized by profound pulmonary vascular congestion and a fulminant clinical course. Although several reports document a role for experimental brain-stem lesions in the production of NPE, there have been only two studies in man correlating specific brain-stem lesions with NPE. The authors report a case of NPE occurring in a patient with von Hippel-Lindau disease and a dorsal medullary syrinx with postoperative dorsal medullary edema. The anatomical location of this patient's lesion is reviewed in the context of alternative theories of the pathogenesis of NPE.

Neurogenic Pulmonary Edema in Monkeys with Global Brain Ischemia (GBI)

Ischemic and traumatic brain insults may be followed by pulmonary failure, which is a frequent cause of death in cases of multi-trauma, cardiac arrest and stroke. Pulmonary edema (PE) can occur secondary to events in the central venous nervous system (CNS). This is generally termed neurogenic pulmonary edema (NPE). It is not known which of the following 4 factors of the modified Starling equation of pulmonary edema development are involved in the development of NPE: a) filtration coefficient, that is, increased membrane permeability; b) abnormal hydrostatic pressure gradient; c) abnormal oncotic pressure gradient; and d) blockage or overwhelming of lymphatic drainage (Fig. 1).

Megadose corticosteroid therapy following experimental traumatic spinal injury

Corticosteroids are frequently used in the treatment of spinal trauma, although neither experimental nor clinical evidence to support their use is persuasive. Recently there have been claims that extremely high doses ("megadoses") of corticosteroids (equivalent to 15 to 30 mg/kg of methylprednisolone) improve neurological recovery compared to results with traditional steroid doses. The authors have compared the effect of megadose dexamethasone and methylprednisolone therapy to that of saline treatment following traumatic cervical spinal injury in the cat. During 6 weeks postinjury, neurological recovery did not differ significantly in corticosteroid-treated and saline-treated animals. Moreover, histopathological changes in the spinal cord were similar in methylprednisolone- and saline-treated cats. Corticosteroid-treated animals had a higher mortality rate than did control animals, with the predominant cause of death being neurogenic pulmonary edema. It is concluded that megadose corticosteroid treatment does not improve neurological recovery in this experimental model of spinal injury, and is associated with increased mortality.

Neurogenic pulmonary oedema

Neurogenic pulmonary oedema is a not uncommon condition with a mortality that may exceed 90%. A fatal case in a 17-month-old child is reported. The literature is reviewed and current theories of the pathogenesis presented. Suggestions are made on how the condition might best be managed.

Neurogenic pulmonary edema

This report presents a patient who developed fulminant pulmonary edema as a complication of an acute subarachnoid hemorrhage. Hemodynamic evaluation revealed low-normal pulmonary arteriolar resistances. Endobronchial fluid was freely suctioned from the patient over a two-day period and had a colloid osmotic pressure and protein content equal to the patient's plasma throughout the entire course. These findings suggest that neurogenic pulmonary edema in this patient was related to increased capillary permeability and may occur independent of pulmonary hemodynamics.