The Influences Of Hypoxemia On BNP Of Patients With Normal Heart Function

Background: BNP is also called NT-proBNP, which mainly stems from ventricles and is primarily composed in the left ventricles. Its contents in the body depend on the conditions of ventricular pressure and the neurhormone regulatory system to some extent. An increase in the volume and the pressure of the ventricles can lead to the increase in the BNP which is existed in blood plasma, and the degree of the increase is directly proportional to the expansion of ventricles and excessive growth of pressure. In recent years, it is publicly found that the changes in the level of BNP in blood plasma can serve as significant guides in the diagnosis, treatment and prognosis of cardiovascular disease, especially the congestive heart failure. And the study also shows that the BNP level is clearly relevant to the standards of KILLIP set up by New York Heart Association. The relationship between the level of BNP and NAYA KILLIP is shown as follows. The first one is BNP<80pg/ml for healthy people. Secondly, NAYAⅠis prescribed as BNP152±16pg/ml for the people who has some wrong with their hearts but there is no obvious symptoms and there is no control in exercises; The third one is called NAYAⅡand is expressed as BNP332±25pg/ml for the people who have the right symptoms when they are tired but no symptoms appears whey they are not. The fourth relation, NAYAⅢcan be prescribed as that there are serious symptoms, slight symptoms and no symptoms respectively for such conditions as tiresome, slight exercises and rest; as a result, this level is expressed as BNP590±31pg/ml. The last one is called NAYAⅣwith the standard of BNP960±34pg/ml, any body who is ranked at this level will show symptoms even when they are at rest; this level of BNP, with a high sensitivity of 95%,can easily tell HF patients from non-HF patients from NAYAⅠto NAYAⅣ. In a majority of articles and documents, it is known to all that there is no congestive heart failure as long as BNP is less than 100pg/ml while there is congestive heart failure when BNP is more than 500pg/ml. however, when a doctor diagnose a patient whose BNP is ranking between 100pg/ml and 500pg/ml, the doctor should consider the patient's clinical manifestations, physical examination, Echocardiogram and other tests results, because some causes that are not related to hearts can lead to an increase in BNP level. In real work, we have found that some hypoxemic patients have unbelievably high BNP, but have no clinical manifestation of congestive heart failure. Excluding the common factors that can influence the level of BNP, such as ages, gender, obesity, renal function and other diseases, there may be other factors can impose influence on BNP. In this paper we will discuss the changes as well as the clinical significance of BNP level of hypoxemic patients who have difficulty in breathing but have no indicators of congestive heart failure, excluding such factors as ages, gender, obesity, renal function and so on.Aims: this experiment aims at investigating the relationship between PaO2 and BNP of some patients who get hypoxemia but have normal heart function, then trough a series of analysis we can known clearly the factors that can influence BNP. Therefore, we can make right diagnosis for those dyspneic patients whose BNP is abnormally high, avoiding the occurrence of misdiagnosis and mistherapy.Resources and methods: 122 patients include the patients who were in our hospital from March, 2007 to March, 2008, whose LVEF is no less than 50% trough echocardiography. According to the different levels of oxygen deficiency, these patients were classified into two groups. One group consist the patients who are not hypoxemic and the other makes up by the hypoxemic patients. The first group is the control group with sixty members while the other has sixty-two members. Within 24 hours since they were in hospital, check their BNP level in blood plasma. And then analyze the relationship between PaO2 and BNP of both groups'patients and the relationship between severity of oxygen deficiency of the first group and the BNP level. Results: We found that the BNP level of the patients in the control group is 56.1±13.2pg/ml while the other group's BNP is 178.7±32.6pg/ml and there is obvious difference between them (P<0.01). The second group is further classified into two subgroups. The first subgroup includes the thirty-six patients with mild hypoxemia and their PaO2 level is ranking between 60 mmHg and 90mmHg, and its BNP is 119.7±18.3pg/ml. The second subgroup includes twenty-six patients with moderate hypoxemia and their PaO2 level is ranking between 40 mmHg and 60mmHg, and its BNP is 245.7±24.2pg/ml. Thus, there is clear difference between the two subgroups (P<0.05). Once the patients in the hypoxemia group are recovered from oxygen deficiency, their BNP level in blood plasma can rise accordingly to 59.2±15.6pg/ml and 67.4±16.4pg/ml, which is significantly differentiated from that of the control group.Conclusion: Firstly, oxygen deficiency can bring about an increase in the BNP level in patients'blood plasma. Furthermore, along with the growth and decline of the degree of oxygen deficiency, the BNP level in blood plasma will grow and decrese accordingly. Thirdly, although hypoxemia can be seen a cause of rising in BNP level, most hypoxemic patients whose BNP level is less than 500pg/ml,or more than 500pg/ml or even more than 300 pg/ml but without cardiac dysfunction should be diagnosed cardiac, apart from some severe hypoxemic patients with BNP more than 500pg/ml. Then the patients whose BNP is between 100pg/ml and 500pg/ml and whose clinical manifestation is dyspnoea should undertake blood gas analysis in order to exclude the effects of hypoxemia of BNP. And the last conclusion is that along with the decline of the blood oxygen partial pressure, the impacts of PaO2 on BNP may cause small pulmonary arteries to contract and increase pulmonary arterial pressure, and resulting in less BNP secreted in right ventricles and higher level of BNP in blood plasma, nevertheless, the space for the increase of BNP level is small because the BNP is mainly secretes in the left ventricles.