Pulmonary function profile of children with sickle cell disease

Background: Lung disease is a major cause of morbidity and mortality in sickle cell disease (SCD). In view of severe anemia, decreased blood oxygen affinity, pulmonary arterial vaso-occlusion, microinfarction and microfibrosis being associated with sickle cell disease; an analysis of pulmonary function in them will be of great interest.Methods: Seventy 6-12 years old children with SCD (SS pattern) were studied as cases along with age, sex and socioeconomic status matched 70 controls (AA pattern) and comparisons drawn between the two groups.Results: All the static and dynamic pulmonary functions such as FVC, FEV1, MMEFR25-75%, PEFR and MVV were found reduced in sickle cell disease, most of them significantly.Conclusions: Any restrictive, obstructive or combined pattern may be produced in SCD depending upon frequency & severity of the acute chest syndrome and vaso-occlusive crises in past.

Increased blood oxygen affinity during digestion in the snakePython molurus

SUMMARYMany snakes exhibit large increases in metabolic rate during digestion that place extensive demands on efficient oxygen transport. In the present study,we describe blood oxygen affinity following three weeks of fasting and 48 h after feeding in the Burmese python (Python molurus). We also report simultaneous measurements of arterial blood gases and haematological parameters. Arterial blood was obtained from chronically implanted catheters,and blood oxygen-dissociation curves were constructed from oxygencontent measurements at known oxygen partial pressure(PO2) values at 2% and 5% CO2. Arterial pH remained constant at approximately 7.6 after feeding, but digestion was associated with an approximately 6 mmol l-1 increase in [HCO3-], while CO2 partial pressure(PCO2) increased from 2.21±0.13 kPa in fasted animals to 2.89±0.17 kPa at 48 h after feeding. Blood oxygen affinity in vivo was predicted on the basis of pH in vivoand the blood oxygen-dissociation curves obtained in vitro. The blood oxygen affinity in vivo increased during digestion, with P50 values decreasing from 4.58±0.11 kPa to 3.53±0.24 kPa. This increase was associated with a significant decrease in the red blood cell [NTP]/[Hb4] ratio (relationship between the concentrations of organic phosphates and total haemoglobin) and a significant decrease in mean cellular haemoglobin content, which is indicative of swelling of the red blood cells. Our data for blood oxygen affinity and arterial oxygen levels, together with previously published values of oxygen uptake and blood flows, allow for a quantitative evaluation of oxygen transport during digestion. This analysis shows that a large part of the increased metabolism during digestion is supported by an increased venous extraction, while arterial PO2(PaO2) and haemoglobin saturation do not vary with digestive status. Thus, we predict that venous PO2 (PvO2) is reduced from a fasting value of 5.2 kPa to 1.6 kPa during digestion.