Bonn, Germany - Severely overweight children often have unforeseen complications when anesthesia is used during medical procedures, according to a study by US researchers.

Researchers at the University of Michigan in Ann Arbor reached the conclusion after studying rates of complications during procedures to assist breathing or clear blockages in airways.

Additionally, blood oxygen levels dropped in 17 per cent of overweight children in the study. Only 9 per cent of participants in a control group of normal and marginally underweight children showed similar results, according to a consumer information centre in Bonn.

The test group included 2,025 children, aged two to 18 years, who had to undergo surgery. They were divided into three groups based on their body mass index: 1,380 were considered to be of normal weight; 351 were registered as overweight; and 294 were considered to be severely overweight or obese.

As there were very few differences between the first two groups, their results were summarized to contrast with the results among obese children. (dpa)