Use of prone ventilation in neurogenic pulmonary oedema

Strategies for the use of mechanical ventilation in the neurologic intensive care unit

Mechanical ventilation in neurologically injured patients presents unique challenges. Patients with acute neurologic injuries may require mechanical ventilation for reasons beyond respiratory failure. There is also a subset of pulmonary pathologic abnormality directly associated with neurologic injuries. Balancing the need to maintain brain oxygenation, cerebral perfusion, and control of intracranial pressure can be in conflict with concurrent ventilator strategies aimed at lung protection. Weaning and liberation from mechanical ventilation also require special considerations. These issues are examined in the ventilator management of the neurologically injured patient.

A change of position for neurogenic pulmonary edema

INTRODUCTION

Stroke is the third most common cause of death in the Western World and is a condition seen by Neurologists, General Physicians and Primary Care Physicians. Neurogenic pulmonary edema can complicate the management of large strokes and cerebral hemorrhage. While the principles of management of this type of pulmonary edema are similar to the more common cardiogenic pulmonary edema, placing a patient in the prone position may be a helpful maneuver facilitating recovery.

METHODS

We describe a case of basilar thrombosis treated with intra-arterial thrombolysis where prone ventilation was employed to treat neurogenic cardio-pulmonary complications.

RESULTS

This resulted in rapid resolution of neurogenic pulmonary edema and patient recovery after recanulation of the basilar artery by intra-arterial urokinase.

CONCLUSION

This technique of prone positioning for ventilation is of importance to physicians who manage stroke and its complications.

Neurogenic pulmonary edema

Neurogenic pulmonary edema (NPE) is usually defined as an acute pulmonary edema occurring shortly after a central neurologic insult. It has been reported regularly for a long time in numerous and various injuries of the central nervous system in both adults and children, but remains poorly understood because of the complexity of its pathophysiologic mechanisms involving hemodynamic and inflammatory aspects. NPE seems to be under-diagnosed in acute neurologic injuries, partly because the prevention and detection of non-neurologic complications of acute cerebral insults are not at the forefront of the strategy of physicians. The presence of NPE should be high on the list of diagnoses when patients with central neurologic injury suddenly become dyspneic or present with a decreased P(a)o(2)/F(i)o(2) ratio. The associated mortality rate is high, but recovery is usually rapid with early and appropriate management. The treatment of NPE should aim to meet the oxygenation needs without impairing cerebral hemodynamics, to avoid pulmonary worsening and to treat possible associated myocardial dysfunction. During brain death, NPE may worsen myocardial dysfunction, preventing heart harvesting.

Prone Positioning to Treat Acute Severe Pulmonary Edema in the Post-Cardiac Surgical Patient: A Case Report

Noncardiogenic pulmonary edema can be fatal without adequate resuscitation. We report, for the first time, the use of prone positioning in the immediate post-cardiac surgical period to treat a patient with profound hypoxemia secondary to massive (noncardiogenic) pulmonary edema. Prone positioning corrects ventilation-perfusion mismatch and allows gravity-dependent drainage of capillary leak-mediated endobronchial pulmonary fluid.

Prone position in mechanically ventilated patients with reduced intracranial compliance

BACKGROUND

Prone position has been used for several years to treat acute lung insufficiency, but in previous studies patients with unstable intracranial pressure (ICP) are mostly excluded. The aim of this study was to investigate if prone position is a safe and useful treatment in patients with reduced intracranial compliance.

METHODS

A consecutive, prospective pilot study of 11 patients admitted to the neuro intensive care unit (NICU) due to traumatic brain injury or intracerebral haemorrhage. ICP, cerebral perfusion pressure (CPP), heart rate (HR), mean arterial blood pressure (MABP), arterial partial pressure of oxygen (PaO(2)), arterial partial pressure of carbon dioxide (PaCO(2)), arterial oxygen saturation (SaO(2)) and respiratory system compliance were measured before, three times during and two times after the patients were placed in the prone position.

RESULTS

No significant changes were demonstrated in ICP, CPP or MABP. PaO(2) and SaO(2) were significantly increased in the prone position. HR was significantly increased in the prone position and after 10 min in the supine post-prone position and the respiratory system compliance was increased after 1 h in the supine post-prone position.

CONCLUSION

Turning NICU patients from the supine to the prone position did not influence ICP, CPP or MABP, but significantly improved patient PaO(2), SaO(2) and respiratory system compliance.

Hypoxia from vasculitic pulmonary haemorrhage improved by prone position ventilation

Ventilation in the prone position is used in patients with acute respiratory distress syndrome (ARDS), although data supporting this strategy are limited, and benefit for patients with other conditions is unclear. The patient in this report had severe hypoxaemia from diffuse alveolar haemorrhage caused by vasculitis with positive antineutrophil cytoplasmic antibodies (ANCA). Ventilation in the prone position improved oxygenation dramatically. This improvement was initially maintained when returned supine, accompanied by increased ventilation. Prone ventilation was used on three consecutive days for 10, 14 and 15 h, respectively. Prone ventilation could improve oxygenation by better ventilation-perfusion (V/Q) matching and improved drainage of blood from the dorsal lung. The improved oxygenation in this patient should encourage the use of prone ventilation in other patients with pulmonary haemorrhage and severe hypoxia.