I can not stress enough how important water is for all of us. Our bodies are made up of between 50 and 65% water as adults. Babies have the most, being born at about 78%. By one year of age, that amount drops to about 65%.  Water can be lost very easily in SMA individuals. There are two types of water loss; Sensible and Insensible. Insensible water loss occurs through breathing dry air and increased breathing rates. Sensible water loss is water loss you can see such as sweat, urine, vomiting. Insensible water loss is the loss of water you can not see such as water evaporation from the skin surface  from fever and the water vapor from the lungs.

In SMA, breathing rates are usually higher than normal. In a healthy person, the rate of breathing should be 12-14 times a minute. In SMA, breathing rates can range from 20 times a minute on up. When the rate of breathing is so high you lose a lot of water from inspiration and expiration. Water replacement helps keep the lungs moist and you are less likely to get atelectasis. In SMA, there is a lot of water lost via breathing fast, open mouth breathing, and sweating.  I highly recommend you give lots of water for hydration. Secretions should be thin not tacky. The recommendation from dieticians for a 1-3 year old is 115-125 cc/kg of water. At the age of 4 ½, Hannah got almost 53 ounces a day of liquids in her diet consisting of  juice, water and/or breastmilk. At 8 ½ years of age, Hannah gets almost 80 ounces of liquid a day. When it is hot outside or when Hannah sweats or has fever she gets more water.

In SMA, the older the child the more water they need. I have never heard of water intoxication from giving to much water to an SMA individual. I am sure it is possible but you would have to give a HUGE amount of water