The threshold or "breakpoint" phenomenon that occurs in AT and DP during a graded exercise test is related to increased plasma catecholamine level. 10-12 The rapid rise in plasma catecholamine level also causes an increase in myocardial oxygen demand (MOD) by increasing both HR and SBP. Furthermore, animal studies have shown that following adrenaline injection, the recorded amplitude of the first heart sound (AHS1) exhibits a similar increase to that of the early systolic wave of the first derivative of left ventricular pressure (LVdP/dtmax), a major determinant of MOD. 1 Several studies have also reported continuous measurement of AHS1 during a graded exercise test. 13-16 Thus, if AHS1 accurately reflects LVdP/dtmax, it may be used in place of SBP for the calculation of DP.he anaerobic threshold (AT), determined by the lactate threshold (LT) or non-invasively from ventilatory responses is widely used for assessing aerobic capacity and optimizing training intensity. 1-4 Tanaka et al showed that the double product (DP; ie, the product of heart rate [HR] and systolic blood pressure [SBP]) increases more steeply above the LT, and has a breakpoint (DPBP) that is associated with the LT. 5 The DPBP occurs at a similar intensity to that of the LT and the AT in healthy subjects as well as patients with coronary artery disease (CAD). 6-8 Further, aerobic exercise training increases oxygen consumption (V O2) at the DPBP similar to the training response to the AT. 9 Thus, DPBP, which is easier to obtain than AT and the LT, appears to be an appropriate surrogate for LT. Background: The double product (DP) breakpoint of heart rate (HR) and systolic blood pressure has been identified as coincident with anaerobic threshold (AT), but there are no simple methods for measuring cardiac metabolic stress (CMS) during an exercise test. It was hypothesized that the DP of HR and the amplitude of the first heart sound (AHS1) (DP-AHS1) would reflect CMS, and thus, the breakpoint in the DP-AHS1 (DPBP-AHS1) could be an alternative method for determining AT.
The time for ETCO to be detected following intubation in the delivery suite is variable emphasising the importance of using clinical indicators to assess correct endotracheal tube position in addition to ETCO monitoring. Capnography is likely to detect ETCO faster than colorimetric devices.
BITI was measured in healthy infants. Further evaluation is needed to determine the significance and usefulness of BITI.
Background: Flexible fiber-optic laryngo-tracheo-bronchoscopy has become widely performed in infants and neonates since the introduction of thin flexible fiberscopes. Laryngomalacia is the most common airway disease in infants causing stridor. Pharyngomalacia, termed pharyngeal occlusion during inspiration, was the second most common airway disease found in our hospital in patients that underwent laryngo-tracheo-bronchoscopy, but the incidence, patient characteristics, and natural course have not been reported in large numbers in Japan. Methods: A retrospective review was performed of medical records on patients admitted to our neonatal intensive care unit during the neonatal period diagnosed with pharyngomalacia between April 2009 and November 2018. Patient characteristics, concurrent airway diseases, comorbidities, and treatment were reviewed. Results: Forty-eight patients were diagnosed with pharyngomalacia. The median gestational age was 37.1 weeks, and the median birthweight was 2,552 g. Patients were diagnosed at a median age of 29 days, and cure was achieved at a median age of 4 months. Twenty-eight patients had concurrent airway diseases, laryngomalacia being the most common. Continuous positive airway pressure or high flow nasal cannula was used in 34 patients. Conclusions: In patients with pharyngomalacia, half were born preterm, and more than half had concurrent airway diseases. The onset and diagnosis were made within the first month of life in more than half of the patients, and resolution was seen mostly within the first 6 months of life. Whenever a patient is suspected of having an airway disease, the pharyngeal space should be carefully observed to diagnose pharyngomalacia.
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