Senthil Kumar, K (2014) Correlation between peripheral perfusion index measured by pulse oximeter and blood pressure in neonates more than 35 weeks of gestation. Masters thesis, Madras Medical College, Chennai.
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Abstract
Peripheral haemodynamics determines oxygen and nutrient delivery to the tissues of the newborn infant. This deals with the microcirculation at the level of tissues, which is vital for adequate tissue perfusion and thus oxygenation. In neonates with adequate perfusion, oxygen consumption is independent of the rate of delivery of oxygen. In neonates with poor perfusion oxygen consumption is dependent on the rate of oxygen delivery, which depends on the microcirculation at the tissue level. For normal tissue perfusion a combination of three major factors is required; good cardiac output, integrity of vasomotor tone and ability of blood to deliver oxygen. (1) Shock is a clinical state characterized by acute failure of the circulatory system in maintaining adequate tissue perfusion (1). This results in inadequate oxygen delivery to cells and causes cellular dysfunction, which finally leads to cell destruction. Risk factors for shock include umbilical cord accident, placental abnormalities, fetal / neonatal hemorrhage, maternal anesthesia / hypotension, intrauterine and/or intrapartum asphyxia, neonatal sepsis, pulmonary air leak syndromes, lung over distension during positive pressure ventilation and cardiac arrhythmias. Depending on the severity of shock, there are three phases of shock, namely compensated phase, decompensated phase, and irreversible stage of shock. In the “compensated phase of shock,” autonomic compensatory mechanisms maintain normal blood flow to the vital organs like heart, brain, and adrenal glands. Blood flow to the nonvital organs like skin, kidney decreases. There is vasodilatation of the blood vessels to vital organs and vasoconstriction of the blood vessels to the nonvital organs. As blood flow to nonvital organs is compromised, there are clinical signs of poor peripheral perfusion like cold extremities, poor pulse volume, prolonged capillary refill time and decreased urine output. In compensated shock, blood pressure is maintained within the normal limit, and heart rate increases. • Clinical shock in neonates can be reasonably predicted when perfusion index is less than 0.91. • Perfusion index less than 0.91 has high sensitivity and low false positivity in predicting clinical shock. • No correlation between systolic blood pressure and perfusion index, negative correlation with diastolic blood pressure (moderately negative) and mean arterial blood pressure (weak negative). • Pulse pressure had positive correlation with perfusion index • An 18% decrease of perfusion index from the baseline, may predict future shock. States like pain, stress, hypothermia also decreases perfusion index. • Perfusion index is unreliable in predicting hypotension.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | peripheral perfusion index; pulse oximeter; blood pressure; neonates; gestation |
| Subjects: | MEDICAL > Neonatology |
| Depositing User: | Kambaraman B |
| Date Deposited: | 23 Jun 2017 07:10 |
| Last Modified: | 23 Jun 2017 07:35 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/290 |
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