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Biomedical subjects

T S Scanlon

Publications and source records attributed to T S Scanlon.

7 recordsLinked to original sources
PubMed1995

Role of minor electrolytes when applied to Stewart's acid-base approach in an acidotic rabbit model.

Current clinical practice regarding acid-base balance is derived from the traditional Henderson-Hasselbalch equation. An alternate theory, developed by Stewart, relates hydrogen ion concentration ([H+]) changes to three independent variables: the strong ion difference, weak acids, and PCO2. The insight into acid-base balance gained by this approach has potentially important clinical applications. To test the theory in vivo, electrolyte and blood gas values were measured in rabbits subjected to a period of hypoxia sufficient to produce a severe metabolic acidosis, followed by a period of reoxygenation. These variables were used to calculate [H+] by Stewart's original formula, which was then compared to the measured value. A high correlation was found between measured and calculated values for a pH range of 7.3-7.6; however, progressive deterioration in correlation was observed outside this range. Perhaps the presence of an unidentified anion, thought to be phosphate, causes a breakdown in the accuracy of Stewart's formula at pH extremes. The addition of phosphate values to the calculation, along with calcium and magnesium, restored the agreement throughout the physiologic range. To make the formula clinically applicable, modification to incorporate phosphate levels is required to achieve the necessary accuracy in biologic solutions at more acidemic pH ranges.

Acidosis↗
PubMed1992

A widely unappreciated cause of failure of an automatic noninvasive blood pressure monitor.

Many anesthesiologists have come to depend on automatic noninvasive blood pressure monitoring to obtain blood pressure (BP) readings. A case is presented in which, during a critical phase of the anesthetic, an automatic noninvasive blood pressure (ANIBP) device not only failed to provide meaningful clinical data but, in fact, gave an error message that was misleading. At the time of the message, the patient was noted to be in ventricular trigeminy at a rate of 92 beats/min. It appears that the repetitive beat-to-beat fall in blood pressure due to the dysrhythmia "fooled" the automatic noninvasive blood pressure device's software algorithm into believing that there was an air leak in the system. Thus, in addition to pointing out an unappreciated and potentially troubling device-related critical event, the present case demonstrates the importance of good human factors design for medical devices used in the critical care setting. In particular, the issue is raised of how medical devices should deal with uncertain or potentially misleading data.

Aged↗
PubMed1991

Recent advances in catalytic antibodies.

Recently the biological machinery of the immune system has been exploited with the aid of mechanistic chemistry to produce catalytic antibodies. Because antibodies can be generated that selectively bind almost any molecule of interest, this new technology offers the potential to tailor-make highly selective catalysts for applications in biology, chemistry and medicine. In addition, catalytic antibodies provide fundamental insight into important aspects of biological catalysis, including the importance of transition-state stabilization, proximity effects, general acid and base catalysts, electrophilic and nucleophilic catalysis, and strain.

Antibodies↗
PubMed1979

Demonstration of interlobar collateral ventilation.

In an ongoing series of experiments on mongrel dogs, three dogs were observed to have incomplete lobar fissures (interlobar connection present) between the left upper and left lower lobes. With the interlobar connection unclamped, selective hypoxia of the left lower lobe caused the electromagnetically measured blood flow to the left lower lobe to decrease 41 +/- 4%, whereas with the interlobar connection clamped selective hypoxia of the left lower lobe caused a 52 +/- 4% decrease in left lower lobe flow (P less than 0.05). Following 100% O2 ventilation and with the interlobar connection unclamped, complete occlusion of the left lower lobe bronchus caused no atelectasis or decrease in left lower lobe blood flow, whereas with the interlobar connection clamped complete occlusion of the left lower lobe bronchus caused complete left lower lobe atelectasis and a 58 +/- 3% decrease in left lower lobe blood flow. Histological confirmation of interlobar pulmonary parenchymal connection was obtained in each dog. We conclude that a sufficient amount of interlobar collateral ventilation can occur in dogs with incomplete lobar fissures to prevent absorption atelectasis and alter lobar blood flow reduction usually caused by selective lobar hypoxia.

Animals↗