The effect of dyshemoglobins on pulse oximetry: Part I,theoretical approach and part II,experimental results using an in vitro test system

Pulse oximeters are known to be inaccurate in the presence of elevated concentrations of carboxyhemoglobin and methemoglobin. This paper attempts to alleviate some of the confusion that exists between fractional and functional saturation, and to clarify the comparison of each with SpO₂. A series of theoretical relationships between pulse oximeter reading (SpO₂) and actual oxygen saturation (both fractional and functional) is derived using simple absorption theory. The theoretical relationships are checked using an experimental in vitro test system. This consists of a blood circuit containing a model finger, capable of simulating the pulsatile transmission signals through a real finger. Theoretical predictions and experimental results are compared and are found to agree well in the presence of carboxyhemoglobin, but less well with methemoglobin. Possible reasons are discussed.     

Breast self-examination: an analysis of self-reported practice

The aim of this study was to investigate the relationship between the performance of breast self-examiniation (BSE) and age, place of residence, ethnic background and religion, as well as whether a group willing to take part in an interview regarding BSE mirrored the whole population. Six hundred and ninety-four (69.4%) women, aged 25–80, responded to the questionnaire. Of gthese, 69.6% examined their breasts. Whether the subjects lived in urban or rural areas was of no importance for practising BSE, nor was country of birth or number of years in Sweden. A larger proportion of women aged 45–80 practised BSE compared with women aged 25–44 ( P < 0.001), the former practising BSE once a month or more. Step-wise logistic regression analysis showed that, for the whole sample as well as for the interview group, age was the only significant predictor of breast self-examination ( P < 0.001). There were no significant differences between the whole sample and the interview group. The importance of younger women performing the examiniation is stressed. Dur to nurses being strategically located in a wide range of geographical locations, allowing them to meet women in different settings, they are a good choice for motivating women to prctise BSE.