University of Saint Mary

About: University of Saint Mary is a education organization based out in Leavenworth, Kansas, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 2276 authors who have published 2399 publications receiving 58990 citations. The organization is also known as: University of St. Mary & University of St Mary.

Weaning from the ventilator using BiPAP in myasthenia gravis.

Abstract: Weaning from mechanical ventilation is frequently difficult in patients recovering from a myasthenia gravis (MG) crisis.4 Typically, such patients are initially treated with high levels of pressure support ventilation. This ventilatory mode delivers positive pressure at the onset of each inspiration triggered by the patient’s effort. During weaning, these levels of pressure support are gradually reduced. Then, before extubation, patients are connected to a Tpiece (an external tube that allows oxygen delivery through the endotracheal tube) to assess their ventilatory capacity without mechanical support. Often, patients with MG are easily weaned to low levels of pressure support only to reach a standstill. Insufficient respiratory muscle strength may cause these patients to repeatedly fail these T-piece trials and extubation attempts. However, prolonged endotracheal intubation increases the risk of airway damage and ventilator-associated pneumonia.1 Noninvasive bilevel positive airway pressure (BiPAP) ventilation delivers adjustable degrees of positive pressure throughout the respiratory cycle to overcome upper airway resistance during inspiration and prevent alveolar collapse at the end of expiration.2 Pressures are delivered through a close-fitting mask, thus avoiding the need for an endotracheal tube. Because it reduces the work of breathing, BiPAP may be an ideal method of gradual weaning for patients with MG who develop ventilator-dependency. We report our experience using BiPAP as a weaning method in five episodes of respiratory failure occurring in three patients with an exacerbation of MG. The patients were mechanically ventilated due to neuromuscular respiratory failure caused by MG crisis. None had alternative explanations for respiratory failure. All patients had failed repeated T-piece trials and were receiving low levels of pressure support ventilation (inspiratory pressure 10 mm Hg and end-expiratory pressures 8 mm Hg) at the time of extubation and institution of BiPAP support. All had been treated with plasmapheresis in the acute phase and received incremental dosages of pyridostigmine during the weaning process, with improved muscle strength documented by serial neurological examinations. Timing of extubation and institution of BiPAP was based on the clinical judgment of the treating physician. Bedside respiratory function tests and arterial blood gases were not consistently measured before extubation. BiPAP ventilation was well tolerated and prevented reintubation in all cases. Before institution of BiPAP, patients had been intubated for a mean time of 13 days (range, 2–26 days). BiPAP inspiratory pressures ranged from 18 to 8 mm Hg and expiratory pressures from 8 to 4 mm Hg. No cases of pneumonia occurred despite all patients having bulbar weakness. Several days of BiPAP ventilation were needed in most cases (Table 1). Prior experience with BiPAP has largely been in patients with underlying pulmonary disease or with chronic neuromuscular disorders. BiPAP may prevent intubation in selected patients with MG, but its value in weaning from the ventilator has not been previously investigated.3 Weaning trials are subjective and dependent on many factors, mostly physician preferences. However, we found BiPAP use may facilitate weaning and shorten the time that pa-

The association of platelet and red cell count with platelet impedance changes in whole blood and light-scattering changes in platelet rich plasma: evidence from the Caerphilly Collaborative Heart Disease Study.

Abstract: This epidemiological study was undertaken to explore possible relationships among various haematological indices, prevalent ischaemic heart disease and platelet "function" as measured by two rather different methods. ADP-induced platelet impedance changes in whole blood were strongly associated with prevalent ischaemic heart disease in a general population of 49-66 year men at increased risk. Adenosine diphosphate (ADP) induced platelet aggregation in platelet rich plasma (PRP) at a constant platelet count and also the whole blood platelet count and red cell (RBC) count were strongly and independently related to ADP-induced platelet impedance changes. Both platelet count and platelet aggregation in PRP assessed by changes in optical density were directly related to increasing platelet "sensitivity" as measured by impedance changes in whole blood but RBC count was inversely related. Positive independent relationships between platelet impedance changes and plasma viscosity and fibrinogen were markedly attenuated when platelet count was taken into account, but this finding does not discount a role for these factors in platelet aggregation. No relationship was noted between white blood cell (WBC) count and platelet impedance changes; however, a significant inverse relationship was noted with platelet aggregation in PRP. These findings indicate that laboratory-based experimental findings can be observed in population based studies, and that these haematological factors may be important indicators of ischaemic disease in the population.