Part 1: The physiology of transition The transition from fetus to neonate is a critical time of physiological adaptation. While the majority of term infants complete this process in a smooth and organized fashion, some infants experience a delay in transition or exhibit symptoms of underlying disease. Careful...

Homeostatic mechanisms ensure that in health the extracellular fluid (ECF) concentration of electrolytes, including calcium, is maintained within well-defined limits. Abnormality in ECF calcium concentration can have profound adverse effects.  The most common means of assessing calcium status is to measure total...

Results of hemoglobin (Hb) and hematocrit (Hct) measurement are routinely used to assess blood loss among trauma patients. But is it necessary to measure both parameters and if not, is one more reliable than the other? There is evidence to suggest that many physicians believe hematocrit is a more sensitive indicator...

Accurate blood gas results depend on a homogeneous blood sample and the necessity for thorough mixing of samples is reflected in written standard operating procedures for blood gas analysis. The results of a recent study suggest, however, that manual mixing techniques routinely used may be inadequate in achieving a...

Acid-base physiology and significance of blood gas results are topics that many students find daunting. Their difficulty is not aided by the non-standard abbreviations used to indicate partial pressure of a gas. The issue is highlighted in a recent letter to the journal Clinical Chemistry.  The authors cite the...

Modern blood gas analyzers often have incorporated technology that allows hemoglobin measurement on the same blood sample used to measure pH, pCO₂ and pO₂. Clinicians working in a UK neonatal intensive care department where such an instrument was routinely used for blood gases were keen to exploit the newly available...

Arterial blood is the standard sample for measurement of pH, pCO₂ and pO₂, but collection of arterial blood can be painful. Furthermore, it is a procedure associated with some risk to the patient and can therefore only be performed by trained, medically qualified staff.   Capillary blood collection by finger or...

Blood gas analysis of umbilical cord blood provides the means for establishing the acid-base status of babies at the time of birth. If there is to be any delay in sampling, the portion of cord from which the sample is to be taken should be double-clamped and thereby isolated from the placenta.  Previous studies have...

Hypoxia and hypoxemia describe states of oxygen deficiency: hypoxia is deficiency in oxygenation at tissue or cellular level whilst hypoxemia is a suboptimal normal partial pressure of oxygen. Hypoxia and hypoxemia are interrelated, as untreated hypoxemia will ultimately result in hypoxia.  It should also be noted...

Where do you go for help, when you are a parent of a child who stops breathing while it sleeps? If you live in the south of Sweden, you go to Halmstad County Hospital, where a team of specialists are ready to monitor your sleeping child by polysomnography (PSG). The neonatal intensive care unit (NICU) in Halmstad has ...