| Abstract | As a result of the previous shortage of tools to assess objectively the
overall physiological status of the respiratory system in infants and young
children, it has been difficult to measure the degree of physiological
disorder or the response to therapy in respiratory diseases such as BPD, the
pediatric version of ARDS, bronchiolitis, pneumonia, asthma and croup in this
patient population. The newborn- four-year old child is
particularly difficult to study because of their lack of cooperation and
size. The recent progress in computer technology made
pulmonary function testing available for this age range and opened up new
possibilities for monitoring changes in disease processes affecting the
respiratory system. This may improve medical management of infants and
children with lung and heart diseases in particular. In 1989, Shannon [49]
proposed in this Journal that the minimum physiological information needed
for the intelligent use of mechanical ventilation (particularly if lower
airway and/or pulmonary parenchymal disease was apparent) required the
measurement of at least 4 variables: i) arterial partial pressure of carbon
dioxide; ii) arterial oxygen saturation; iii) the mechanical time constant of
the lung and iv) FRC. In many circumstances, arterial CO2 is approximated by
alveolar (end-tidal) CO2 and the arterial oxygen saturation is obtained from
pulse oximetry accurately if perfusion is adequate. The mechanical time
constant and FRC are easily measured by the techniques described above and
together provide important information concerning appropriate ventilator
settings for a given disease. The described techniques bring new insights and
awareness, but also new responsibilities in the management of infants and
children with respiratory compromise. Not all of these techniques need to be
applied to all infants in the ICU. Not all the assumptions upon which some of
the techniques we have described are based will prove true. Any such methods
which do not withstand solid scientific testing must be quickly discarded and
replaced with better and (hopefully) easier methods. |