In preparation for the starting the CPAP on a few children in the neonatal intensive care unit run by Dr. Rylance, we have been looking at the admissions and deaths of children to Chatinka (the neonatal ward) by weight. We start recording a birthweight of 500g, (we have only seen one below this) up to 1499g, grouping admissions into 100g bands, ie 500-599g, 600-699g on up to 1499g. We gathered the data from the admission books that the nurses keep, where each patient has an admission number, admission date, a name (usually of the mother), sex, apgar score, weight, notes and an outcome. If the baby dies, it has the date of death, but if the child lives it just says “lived”. In all we looked at data from January to June 2010 and the overall mortality for children below 1500g was 57%. The mortality below 800g, however, is 100%.

When children are born so small (healthy full term size is 3500g) they are often very premature and undeveloped, lacking the basic components needed to survive, even with the support of Chatinka. Another complication is that many women don’t know an approximate conception date, leaving doctors to guess whether that child is full term, developed and very small, possibly due to lack of maternal nutrition, or is small due to prematurity, which can affect how the child is treated.

Considering the challenges of the environment and the resources of Chatinka, which are fairly good from what I can tell, this is decent mortality rate. It is unlikely that these very small babies, even in a Western setting would survive, especially without many complications in later life.

Once you reach a birthweight of 1200g and above the mortality starts to fall below the average, down to 35% in the 1400g band. Dr. Rylance thinks that we should use this as a guide when deciding which children to start CPAP on, starting with children who stand a chance of doing better, but are still premature and need the extra push to start breathing.

The CPAP, continuous positive airway pressure, if designed to force air into the lungs. This is useful for a variety of applications, but in the case of premature babies, they often suffer from surfactant deficient lung disease. Surfactant a fluid that coats the alveoli, helps reduce the surface tension created by the water on the alveoli. The same surface tension that makes water bead up, also wants to force the alveoli to collapse, letting the water be closer together, rather than spread out on the little balloon like alveoli. To breathe you must overcome this “collapsing force” to expand the alveoli. Technically you do this by moving your diaphragm and creating negative pressure in the chest cavity, encouraging outside, higher pressure air to rush into the lungs. Without surfactant though, more effort must be put in to do this and these small babies spend their few calories just in the effort of breathing. Without assistance they lose weight quickly and essentially become too tired to breathe, which is leads to apnea of prematurity and death. CPAP can reduce this weight loss and death by providing the extra push of air to help babies inflate their lungs. Dr. Machen explained it by using the example of blowing up a balloon. When you are first trying to inflate the balloon, it is very hard, but once it expands, adding more air, or taking a bit out and then adding a bit more (like breathing), becomes much easier.