Pulse Oximetry with Two Infrared Wavelengths without Calibration in Extracted Arterial Blood.

Oxygen saturation in arterial blood (SaO2) provides information about the performance of the respiratory system. Non-invasive measurement of SaO2 by commercial pulse oximeters (SpO2) make use of photoplethysmographic pulses in the red and infrared regions and utilizes the different spectra of light absorption by oxygenated and de-oxygenated hemoglobin. Because light scattering and optical path-lengths differ between the two wavelengths, commercial pulse oximeters require empirical calibration which is based on SaO2 measurement in extracted arterial blood. They are still prone to error, because the path-lengths difference between the two wavelengths varies among different subjects. We have developed modified pulse oximetry, which makes use of two nearby infrared wavelengths that have relatively similar scattering constants and path-lengths and does not require an invasive calibration step. In measurements performed on adults during breath holding, the two-infrared pulse oximeter and a commercial pulse oximeter showed similar changes in SpO2. The two pulse oximeters showed similar accuracy when compared to SaO2 measurement in extracted arterial blood (the gold standard) performed in intensive care units on newborns and children with an arterial line. Errors in SpO2 because of variability in path-lengths difference between the two wavelengths are expected to be smaller in the two-infrared pulse oximeter.

Gradenigo's syndrome: is fusobacterium different? Two cases and review of the literature.

Gradenigo's syndrome is a rare but life threatening complication of acute otitis media (AOM), which includes a classic triad of otitis media, deep facial pain and ipsilateral abducens nerve paralysis. The incidence of Fusobacterium necrophorum infections has increased in recent years. We describe two cases of Gradenigo's syndrome caused by F. necrophorum. Additional four cases were identified in a review of the literature. Gradenigo's syndrome as well as other neurologic complications should be considered in cases of complicated acute otitis media. F. necrophorum should be empirically treated while awaiting culture results.

Necrotizing upper limb fasciitis in a newborn: an uncommon life-threatening event.

Necrotizing fasciitis is an uncommon but life-threatening infection in the pediatric population. It is rarely reported in neonates. In these rare cases, the reported origin of infection was the umbilical cord stump, infection due to circumcision, and similar lesions. We hereby report a 3-week-old neonate sustaining necrotizing fasciitis without detectable origin of infection. We describe the clinical course of her illness, the diagnostic process, and eventual surgical intervention. We discuss the importance of awareness to this potentially lethal infectious disease and the need for urgent use of certain imaging modalities and aggressive surgical approach.

Mannose-binding lectin-deficient mice are susceptible to infection with Staphylococcus aureus.

Gram-positive organisms like Staphylococcus aureus are a major cause of morbidity and mortality worldwide. Humoral response molecules together with phagocytes play a role in host responses to S. aureus. The mannose-binding lectin (MBL, also known as mannose-binding protein) is an oligomeric serum molecule that recognizes carbohydrates decorating a broad range of infectious agents including S. aureus. Circumstantial evidence in vitro and in vivo suggests that MBL plays a key role in first line host defense. We tested this contention directly in vivo by generating mice that were devoid of all MBL activity. We found that 100% of MBL-null mice died 48 h after exposure to an intravenous inoculation of S. aureus compared with 45% mortality in wild-type mice. Furthermore, we demonstrated that neutrophils and MBL are required to limit intraperitoneal infection with S. aureus. Our study provides direct evidence that MBL plays a key role in restricting the complications associated with S. aureus infection in mice and raises the idea that the MBL gene may act as a disease susceptibility gene against staphylococci infections in humans.