The IR-bronchial washing assay represents a novel diagnostic methodology to the microvascular injury-induced pulmonary edema. However, the method is only valid over a certain period following HES infusion. Over time, HES is broken down into smaller size molecules, and, therefore, the specificity of the method is inevitably lost. Clinical pharmacokinetic and pharmacodynamic studies showed that, over a 12 h period, the average size of infused PENTASPAN (200/0.5 HES) is approximately 11.28 nm , which should still restrict the molecules within the pulmonary capillaries. Table 2 shows that 58% of ‘noninjured patients’ (seven of 12) in the risk group also had leakage. The significance of identifying a leak in the ‘at risk’ group can not be underestimated – this would imply aggressively treating these patients to prevent future complications and further lung insult. It is well known that ARDS may take up to 48 h to demonstrate overt clinical features, such as the classic chest x-ray findings. Thus, it is possible that the group at risk may have developed later into the classic ARDS models, while the IR method detected leakage in these patients at an early stage in the course of their disease. buy ortho tri-cyclen online
As mentioned, the PaO2/FiO2 ratio assesses the pulmonary gas exchange function rather than addressing the pathophysiological changes in pulmonary vascular permeability. In this sense, the IR technique could provide an additional parameter in the diagnosis of ALI/ARDS. If this technique were to obtain clinical validity in the diagnosis of ARDS and in the identification of at-risk patients, then its application must also be balanced with the clinical picture.
Table 2. A 2×2 contingency table comparing clinical Partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) values with the IR spectroscopic classification
|Group||Injury group (PaO2/FiO2 mmHg)||Risk group (PaO2/FiO2300 mmHg)|
|IR positive for||40||7|
|IR negative for||15||5|