Neurogenic pulmonary edema

Tacrolimus Prevents Mechanical and Humoral Alterations in Brain Death-Induced Lung Injury in Pigs

RATIONALE

Donor brain death-induced lung injury may compromise graft function after transplantation. Establishing strategies to attenuate lung damage remains a challenge because the underlying mechanisms remain uncertain.

OBJECTIVES

The effects of tacrolimus pretreatment were evaluated in an experimental model of brain death-induced lung injury.

METHODS

Brain death was induced by slow intracranial infusion of blood in anesthetized pigs after randomization to tacrolimus (orally administered at 0.25 mg. kg-1 BID the day before the experiment and intravenously at 0.05 mg. kg-1 one hour before the experiment; n=8) or placebo (n=9) pretreatment. Hemodynamic measurements were performed 1, 3, 5 and 7 hours after brain death. After euthanasia of the animals, lung tissue was sampled for pathobiological and histological analysis, including lung injury scoring (LIS).

MEASUREMENTS AND MAIN RESULTS

Tacrolimus pretreatment prevented increases in pulmonary artery pressure, pulmonary vascular resistance and pulmonary capillary pressure and decreases in systemic artery pressure and thermodilution cardiac output associated with brain death. After brain death, the ratio of the partial arterial O2 pressure to the inspired O2 fraction (PaO2/FiO2) decreased, which was prevented by tacrolimus. Tacrolimus pretreatment prevented increases in the interleukin (IL)-6-to-IL-10 ratio, vascular cell adhesion molecule-1, circulating levels of IL-1β, IL-6-to-IL-10 ratio and glycocalyx-derived molecules. Tacrolimus partially decreased apoptosis [Bax-to-Bcl2 ratio (p=0.07) and the number of apoptotic cells in the lungs (p<0.05)] but failed to improve LIS.

CONCLUSIONS

Immunomodulation through tacrolimus pretreatment prevented pulmonary capillary hypertension as well as the activation of inflammatory and apoptotic processes in the lungs after brain death; however, LIS did not improve.

Role of autonomic system imbalance in neurogenic pulmonary oedema

Neurogenic pulmonary oedema (NPE) is a life-threatening complication that develops rapidly and dramatically after an injury to the central nervous system (CNS). The autonomic system imbalance produced by severe brain damage may play an important role in the development of NPE. Activation of the sympathetic nervous system and inhibition of the vagus nerve system are essential prerequisites for autonomic system imbalance. The more severe the damage, the more pronounced the phenomenon. Sympathetic hyperactivity is associated with increased release of catecholamines from peripheral sympathetic nerve endings, which can cause dramatic changes in haemodynamics and cause pulmonary oedema. On the other hand, the abnormal inflammatory response caused by vagus nerve inhibition may also play an important role in the pathogenesis of NPE. The perspective of autonomic system imbalance seems to perfectly integrate the existing pathogenesis of NPE and can explain the entire development progression of NPE.

Mechanical versus humoral determinants of brain death-induced lung injury

Background

The mechanisms of brain death (BD)-induced lung injury remain incompletely understood, as uncertainties persist about time-course and relative importance of mechanical and humoral perturbations.

Methods

Brain death was induced by slow intracranial blood infusion in anesthetized pigs after randomization to placebo (n = 11) or to methylprednisolone (n = 8) to inhibit the expression of pro-inflammatory mediators. Pulmonary artery pressure (PAP), wedged PAP (PAWP), pulmonary vascular resistance (PVR) and effective pulmonary capillary pressure (PCP) were measured 1 and 5 hours after Cushing reflex. Lung tissue was sampled to determine gene expressions of cytokines and oxidative stress molecules, and pathologically score lung injury.

Results

Intracranial hypertension caused a transient increase in blood pressure followed, after brain death was diagnosed, by persistent increases in PAP, PCP and the venous component of PVR, while PAWP did not change. Arterial PO₂/fraction of inspired O₂ (PaO₂/FiO₂) decreased. Brain death was associated with an accumulation of neutrophils and an increased apoptotic rate in lung tissue together with increased pro-inflammatory interleukin (IL)-6/IL-10 ratio and increased heme oxygenase(HO)-1 and hypoxia inducible factor(HIF)-1 alpha expression. Blood expressions of IL-6 and IL-1β were also increased. Methylprednisolone pre-treatment was associated with a blunting of increased PCP and PVR venous component, which returned to baseline 5 hours after BD, and partially corrected lung tissue biological perturbations. PaO₂/FiO₂ was inversely correlated to PCP and lung injury score.

Conclusions

Brain death-induced lung injury may be best explained by an initial excessive increase in pulmonary capillary pressure with increased pulmonary venous resistance, and was associated with lung activation of inflammatory apoptotic processes which were partially prevented by methylprednisolone.

Analytic Reviews : Organ Procurement and Brain Death in Trauma Patients

The success rates and effectiveness of transplantation programs continue to increase, as does the need for cadaveric organs. Increasing organ procurement is a worthwhile goal that can be fully justified on economic, humanistic, and ethical bases. Although a great deal of progress has been made in terms of public and political awareness of organ procurement problems, additional changes and further education will be necessary before the number of cadaveric organs that are needlessly wasted can be reduced.

Management of patients with unsurvivable head in juries or patients who are candidates for organ donation is a complex task involving critical care management, the declaration of brain death, and the identification of, and request for, organ donation from next of kin. This process involves the coordinated efforts of neurosur geons, critical care specialists, social workers, and the transplant team coordinators in organ procurement pro grams. Patients are best managed in tertiary centers that have staffs with the expertise and interest in performing these tasks. The time to cardiac death in brain-dead pa tients is frequently short and is hastened by the develop ment of rapidly progressive derangements in gas ex change, fluid and electrolyte homeostasis, temperature regulation, coagulation, and cardiovascular function. Premature death under these circumstances continues to be a major reason for organ-procurement failure. Ag gressive monitoring and treatment of the multiple med ical problems encountered, however, may reduce the number of patients who die prematurely and thus in crease organ procurement rates.

Hypertensive emergencies: a new clinical approach

The expression 'hypertensive urgencies' includes many diseases. The unifying features of these diseases are a high level of arterial pressure and acute distress of one or more organs. The aim of the review was to define the idea of the 'acute hypertension' as a new concept, different from 'chronic hypertension'. Acute hypertension might be related to 'organ damage' because it is the cause, the consequence or an effect of the acute stress. We compounded a narrative review which has included analyses of 373 articles. The structure of the search strategy included a literature search of PubMed, MEDLINE, Cochrane Library and Google Scholar databases. We applied the following inclusion criteria: prospective double-blind randomised controlled trials, experimental animal work studies, case-control studies and recruiting patients representative of the general sick population. In this review, the diseases included in the term 'hypertensive emergencies' share 'acute' hypertension. This is a new idea that emphasises the suddenly increased arterial pressure, irrespective of the initial arterial pressure and independent of the goals of hypertension control. The 'hypertensive emergencies' have been grouped together in three subsets: (1) diseases that result from acute hypertension that is caused by faulty regulation of the peripheral circulation (acute primary hypertension), (2) diseases that produce hypertension (acute secondary hypertension) and 3) diseases that have hypertension as an effect of the acute stress caused by the principle disease (acute associated hypertension). This review highlights a novel idea: acute hypertension is a common sign of different diseases characterised by the sudden surge of arterial pressure, so overwhelming the difference between hypertensive emergencies and urgencies. The judgment of acute hypertension is independent of the initial arterial pressure, normotension or hypertension and is linked with the transient failure of the baroreflex. Hypertensive emergencies are grouped together because all of these diseases require prompt therapy to prevent the negative outcomes of acute hypertension.

Brain-lung crosstalk: Implications for neurocritical care patients

Major pulmonary disorders may occur after brain injuries as ventilator-associated pneumonia, acute respiratory distress syndrome or neurogenic pulmonary edema. They are key points for the management of brain-injured patients because respiratory failure and mechanical ventilation seem to be a risk factor for increased mortality, poor neurological outcome and longer intensive care unit or hospital length of stay. Brain and lung strongly interact via complex pathways from the brain to the lung but also from the lung to the brain. Several hypotheses have been proposed with a particular interest for the recently described “double hit” model. Ventilator setting in brain-injured patients with lung injuries has been poorly studied and intensivists are often fearful to use some parts of protective ventilation in patients with brain injury. This review aims to describe the epidemiology and pathophysiology of lung injuries in brain-injured patients, but also the impact of different modalities of mechanical ventilation on the brain in the context of acute brain injury.

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.

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.

The systemic implications of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is analogous to a pathophysiological watershed, disrupting brain integrity and function and precipitating an array of systemic derangements including cardiovascular, respiratory, endocrine, hematological, and immune dysfunction. Extracerebral organ dysfunction is closely linked to the magnitude of the primary neurological insult, suggesting neurogenic, neuroendocrine and neuroimmunomodulatory mechanisms. Systemic organ involvement is associated with increased mortality and neurological impairment, even after adjustment for other outcome predictors such as the severity of the initial neurological injury. This may be a reflection of secondary brain injury precipitated by hypoxemia, circulatory failure, fever, or hyperglycemia, all of which have been linked to adverse clinical outcomes. Interventions to avert or reverse these and other perturbations need to be tested in clinical trials as they represent opportunities to improve survival and neurological recovery in patients with SAH.

Extracerebral organ dysfunction in the acute stage after aneurysmal subarachnoid hemorrhage

In patients with aneurysmal subarachnoid hemorrhage (SAH), secondary complications are an important cause of morbidity and case fatality. Delayed cerebral ischemia and hydrocephalus are important intracranial secondary complications. Potentially treatable extracranial complications are also frequently observed, and some are related to the occurrence of delayed cerebral ischemia and outcome. In addition to the occurrence of an inflammatory response and metabolic derangements, cardiac and pulmonary complications are the most common extracranial complications. This article provides an overview of the most common extracranial complications in patients with SAH and describes their effects on outcome and delayed cerebral ischemia.

Neurogenic pulmonary edema during intracranial endovascular therapy

Neurogenic pulmonary edema (NPE) is a well-known complication of acute brain injury. Neurogenic stunned myocardium (NSM) occurs clinically in a significant subset of patients with NPE. A 49-year-old woman developed refractory cerebral vasospasm requiring angioplasty following a subarachnoid hemorrhage. During angioplasty, NPE with NSM manifested as acute pulmonary edema associated with elevated pulmonary artery occlusion pressure and reduced cardiac output. Evaluations disclosed a right insular infarction, cardiac wall motion abnormalities, and electrocardiographic characteristics of NSM. The NSM completely resolved, and the neurological outcome was good. A 56-year-old woman developed NPE during complicated coil embolization of an internal carotid artery aneurysm. Cardiac function was normal, and the NPE resolved with a brief period of mechanical ventilation and diuresis. The delayed appearance of NSM and NPE during endovascular therapy in these patients implies a degree of risk for sympathetically mediated cardiopulmonary dysfunction during complex intracranial endovascular procedures.

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 transplantation: the role of brain death in donor lung injury

The paucity of suitable lung donors and the high early mortality as the result of primary graft failure remain major challenges in pulmonary transplantation. There is evidence that the lung is injured in the donor by the process of brain death and often is made unusable or fails posttransplantation after amplification of the injury by the process of ischemia-reperfusion. An understanding of the mechanism of donor lung injury could lead to the development of new treatment strategies for the donor to reduce lung injury, increase the number of donors with acceptable lungs, and improve the results of transplantation. The pathophysiology of brain death is complex and involves sympathetic, hemodynamic, and inflammatory mechanisms that can injure the lung. The literature is reviewed, and these mechanisms are discussed together with their possible interrelations.

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.

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.

Deaths of children during an outbreak of hand, foot, and mouth disease in sarawak, malaysia: clinical and pathological characteristics of the disease. For the Outbreak Study Group

From April through June 1997, 29 previously healthy children aged <6 years (median, 1.5 years) in Sarawak, Malaysia, died of rapidly progressive cardiorespiratory failure during an outbreak of hand, foot, and mouth disease caused primarily by enterovirus 71 (EV71). The case children were hospitalized after a short illness (median duration, 2 days) that usually included fever (in 100% of case children), oral ulcers (66%), and extremity rashes (62%). The illness rapidly progressed to include seizures (28%), flaccid limb weakness (17%), or cardiopulmonary symptoms (of 24 children, 17 had chest radiographs showing pulmonary edema, and 24 had echocardiograms showing left ventricular dysfunction), resulting in cardiopulmonary arrest soon after hospitalization (median time, 9 h). Cardiac tissue from 10 patients showed normal myocardium, but central nervous system tissue from 5 patients showed inflammatory changes. Brain-stem specimens from 2 patients were available, and both specimens showed extensive neuronal degeneration, inflammation, and necrosis, suggesting that a central nervous system infection was responsible for the disease, with the cardiopulmonary dysfunction being neurogenic in origin. EV71 and possibly an adenovirus, other enteroviruses, or unknown cofactors are likely responsible for this rapidly fatal disease.

Subarachnoid hemorrhage and myocardial damage clinical and experimental studies

Subarachnoid hemorrhage (SAH) due to aneurysmal rupture is frequently complicated by cardiopulmonary episodes, including sudden death. We investigated the pathogenesis of cardiopulmonary complications from clinical observation of 715 cases with SAH. There was transient left ventricular asynergy in 9.4% (67/715) of the cases, which consisted of mechanical heart failure and myocardial necrosis. Plasma catecholamine concentration was higher in these patients compared with those without left ventricular asynergy. Transient left ventricular asynergy was considered to result from myocardial derangement: "a panic myocardium," due to a sudden burst of catecholamine. Concerning arrhythmia in SAH, cases with life-threatening arrhythmia, such as ventricular tachycardia or ventricular fibrillation, had higher concentrations not only of plasma catecholamine but also of serum CK-MB, myosin light chain and troponin T, compared with patients who had no ventricular arrhythmia. This implies that life-threatening arrhythmia in SAH would result from myocardial damage due to catecholamine. We devised a novel animal model of SAH in order to clarify the relation between sympathetic nervous activity and myocardial damage immediately after the onset of SAH. The animal experiments showed that sympathetic nervous activity as well as cardiac contractility were transiently elevated, but cardiac function subsequently declined. Serum CK-MB was increased from the onset of SAH and a high value was maintained throughout the entire experimental period. In conclusion, extraordinary transient enhancement of sympathetic nervous activity induces myocardial damage resulting from what is characterized by "a panic myocardium."

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.

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.

Causes and outcome of mechanical ventilation in patients with hemispheric ischemic stroke

OBJECTIVE

To attempt to determine factors that influence outcome in mechanically ventilated patients with ischemic hemispheric stroke.

MATERIAL AND METHODS

We reviewed data on 24 mechanically ventilated patients with an ischemic stroke in the territory of the middle cerebral artery, who had been admitted to a medical, neurologic, or neurosurgical intensive-care unit during the period between 1976 and 1994.

RESULTS

The circumstances surrounding mechanical ventilation were generalized tonic-clonic seizures or status epilepticus (N = 6), progression to stupor and inability to protect the airway from brain swelling (N = 8), or--most commonly--bilateral pulmonary edema from congestive heart failure (N = 10). Of the 24 patients, 17 patients died (12 of neurologic causes and 5 of cardiac arrest or cardiac arrhythmias). Of the seven surviving patients, however, four with seizures and one with pulmonary edema were functionally independent.

CONCLUSION

Three clinical scenarios generally underlie mechanical ventilation in patients with ischemic hemispheric stroke (generalized tonic-clonic seizures, brain swelling, and bilateral pulmonary edema). The outcome in patients with an ischemic hemispheric stroke and a subsequent need for mechanical ventilation is poor; however, survival and independent function are possible if seizures or pulmonary edema prompt ventilatory support.

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 effects of brain death on cardiopulmonary hemodynamics and pulmonary blood flow characteristics

Deterioration of donor lung function contributes to the shortage of donor organs and early postoperative failure after transplantation. A decrease in donor pulmonary function is associated with opacification of lung fields on radiographs, rendering the lungs unsuitable for transplantation, which may be related to the effects of brain death (BD) on pulmonary hemodynamics. Twenty mongrel canines (25.5 +/- 0.7 kg) underwent 20 BD experiments using a previously validated BD organ donor model. An ultrasonic flowmeter was applied on the pulmonary artery and micromanometers were inserted into the right ventricle, pulmonary artery, and left atrium to measure, which allowed the hemodynamic assessment and impedance profile analysis of the pulmonary vasculature by Fourier transformation. Characteristic impedance (Zo) was compared with input resistance (RIN) and with calculated pulmonary vascular resistance (PVR), the conventional index. Right ventricular hydraulic power was analyzed and divided in its components oscillatory and steady power. The results are expressed as means and SEM (analysis of variance, paired two-tailed t tests). Cushing reflex, hemodynamic response, and diabetes insipidus were consistent findings following BD. PVR, Zo, and RIN decreased significantly (p < 0.05) from 367 +/- 40 dyne.s.cm-5, 226 +/- 13 dyne.s.cm-5, and 771 +/- 52 dyne.s.cm-5 to 261 +/- 25 dyne.s.cm-5, 159 +/- 10 dyne.s.cm-5, and 651 +/- 69 dyne.s.cm-5 6 h after BD. Pulmonary artery blood flow increased significantly from 1,499 +/- 107 mL/min to 2,064 +/- 209 mL/min (p < 0.05) after BD. Hydraulic power increased from 69 +/- 6 mW to 104 +/- 13 mW (p < 0.05) and the oscillatory power to steady power ratio of 33%/67% changed to 23%/77% following BD. Extravascular pulmonary water content increased significantly by 10% after BD. BD causes a significant change in pulmonary vascular hemodynamics. The decrease in impedance and right ventricular afterload may lead to significant pulmonary overflow injury and edema. The increase in steady power represents an important reserve of the right ventricle to sustain pulmonary blood flow following BD.

[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.

Neurogenic pulmonary edema: case reports and review

Neurogenic pulmonary edema (NPE) is a relatively common though often subclinical complication of a variety of central nervous system insults (trauma, hemorrhage, seizures, etc.) in children and adults. The syndrome probably results from massive centrally mediated sympathetic discharge and generalized vasoconstriction, and often presents in the emergency department (ED). The symptoms are likely to be mistaken for aspiration pneumonia. Treatment consists of ventilatory support, including positive end-expiratory pressure, and aggressive measures to reduce intracranial pressure. We present four cases of NPE and review its recognition and emergent management.

Capsaicin-sensitive nerves exert an inhibitory effect on the development of fibrin-induced pulmonary edema in rats

This study was undertaken to evaluate the role of vagal nerves in the development of neurogenic pulmonary edema. We injected fibrinogen and thrombin into the cisterna magna of rats, a model of neurogenic pulmonary edema. When the vagal nerves were left intact, pulmonary edema occurred (fibrin-induced pulmonary edema) at a rate of 33%. Vagotomy at the midcervical portion increased the incidence of pulmonary edema to a rate of 100%, whereas pretreatment with atropine did not affect the incidence. These results suggested that vagal afferent nerves or nonadrenergic-noncholinergic efferent nerves played an important role in inhibiting the development of fibrin-induced pulmonary edema. Furthermore, in vagotomized and vagal nerve-intact rats pretreated with capsaicin, the incidence of pulmonary edema was 100%. Pretreatment with a substance P antagonist, [D-Pro2, D-Trp7,9]-SP, also increased the incidence to 100% in the vagal nerve-intact rats. On the other hand, intravenous administration of some neuropeptides that may be released from the capsaicin-sensitive nerves (e.g., substance P or calcitonin gene-related peptide) inhibited the development of pulmonary edema in vagotomized rats. We concluded that the vagal capsaicin-sensitive nerves exerted an inhibitory effect on the development of fibrin-induced pulmonary edema.

Neurogenic pulmonary edema after trigeminal nerve blockade

Acute neurogenic pulmonary edema developed immediately after injection of bupivacaine hydrochloride into the trigeminal cistern of a 32-year-old man with atypical facial pain and no prior history of cardiopulmonary problems. This complication of trigeminal nerve blockade has not been reported previously, to our knowledge. Associated neurologic deficits suggest a key role for the brain stem in the pathogenesis of this disorder.

Altered capillary permeability in neurogenic pulmonary oedema

Two cases of fatal neurogenic pulmonary oedema are depicted. The hemodynamic study failed to document any hypertensive crisis or pulmonary hypertension. By contrast, the low values of pulmonary capillary wedge pressures and the high protein concentration in tracheal fluid suggest a pulmonary capillary wall lesion.

Nucleus tractus solitarius lesions elevate pulmonary arterial pressure and lymph flow

The effects of lesions of the nucleus tractus solitarius (NTS) on pulmonary vascular pressure and pulmonary lymph flow were investigated in 6 halothane-anesthetized sheep. After lesions of the NTS were created using bilateral thermocoagulation, pulmonary artery pressure rose to 150% of baseline and remained elevated for the 3-hour duration of the experiment. Systemic and left atrial pressures did not change. Pulmonary lymph flow doubled within 2 hours; the lymph-plasma protein ratio was unchanged from baseline. Sham NTS lesions and lesions lateral to NTS produced no changes. These experiments demonstrate that lesions of the central nervous system can alter pulmonary vascular pressures and transcapillary fluid flux independently of effects upon the systemic circulation. These findings may have relevance for the understanding of neurogenic pulmonary edema in humans.