Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%–4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse oximetry.

Despite the fact that pain is the most common complaint at the end of life, pain management may be suboptimal for some primary diagnoses. Admission diagnosis is the strongest predictor of pain control. Patient with cancer achieve the best pain control, and chronic obstructive pulmonary disease patients are the least likely to have their pain adequately treated.

Romem A; Romem A; Koldobskiy D; Scharf SM. Diagnosis of obstructive sleep apnea using pulse oximeter derived photoplethysmographic signals.

Background: Fiberoptic bronchoscopy (FOB) with transbronchial biopsy (TBB) is complicated by a pneumothorax in 1-4% of cases. Performance of routine post-TBB chest radiography (CXR) results in an extremely low diagnostic yield but nevertheless is the common clinical practice prevailing today. It has previously been suggested that routine post-TBB CXR could be avoided in asymptomatic patients. Objective: The objective of this study was to prospectively assess the feasibility and safety of this approach. Methods: The study group included 201 consecutive patients who underwent FOB with TBB at our institution between January 2009 and September 2014. All subjects completed a preprocedural, a 2-hour postprocedural, and a 24- to 48-hour postprocedural symptom questionnaire (chest pain, dyspnea, and cough). Post-TBB CXR was ordered by the treating physician only if indicated. All cases of pneumothorax were documented. Additionally, the following information was recorded: sex, age, immune status, indication for FOB, total number of biopsies done, lobe sampled, and pulse oxygen saturation. Results: Sixteen CXRs were ordered by the treating physician due to suspected pneumothorax (8%). Early-onset pneumothorax (i.e. within 2 h of TBB) was diagnosed radiologically in 6 patients (3%). Two late-onset pneumothoraxes (1%) were diagnosed more than 24 h after TBB. No pneumothoraxes of clinical significance were diagnosed among asymptomatic patients without significant oxygen desaturation events. Conclusions: Among asymptomatic patients without significant desaturation events, pneumothorax is rare and usually of negligible clinical significance. Therefore, performance of routine CXR after TBB is not necessary and can be safely avoided in this category of patients.

Treatment with doxycycline is safe and efficacious in preventing TBRF after suspected exposure to ticks in a high-risk environment. (ClinicalTrials.gov number, NCT00237016 [ClinicalTrials.gov].).