ABSTRACT
Near-infrared spectroscopy (NIRS) could be a useful continuous, non-invasive technique for monitoring the effect of partial pressure of carbon dioxide (PaCO2) fluctuations in the cerebral circulation during ventilation. The aim of this study was to examine the efficacy of NIRS to detect acute changes in cerebral blood flow following PaCO2 fluctuations after confirming the autoregulation physiology in piglets. Fourteen piglets (<72 h of life) were studied. Mean arterial blood pressure, oxygen saturation, pH, glycemia, hemoglobin, electrolytes, and temperature were monitored. Eight animals were used to evaluate brain autoregulation, assessing superior cava vein Doppler as a proxy of cerebral blood flow changing mean arterial blood pressure. Another 6 animals were used to assess hypercapnia generated by decreasing ventilatory settings and complementary CO2 through the ventilator circuit and hypocapnia due to increasing ventilatory settings. Cerebral blood flow was determined by jugular vein blood flow by Doppler and continuously monitored with NIRS. A decrease in PaCO2 was observed after hyperventilation (47.6±2.4 to 29.0±4.9 mmHg). An increase in PaCO2 was observed after hypoventilation (48.5±5.5 to 90.4±25.1 mmHg). A decrease in cerebral blood flow after hyperventilation (21.8±10.4 to 15.1±11.0 mL/min) and an increase after hypoventilation (23.4±8.4 to 38.3±10.5 mL/min) were detected by Doppler ultrasound. A significant correlation was found between cerebral oxygenation and Doppler-derived parameters of blood flow and PaCO2. Although cerebral NIRS monitoring is mainly used to detect changes in regional brain oxygenation, modifications in cerebral blood flow following experimental PaCO2 changes were detected in newborn piglets when no other important variables were modified.
ABSTRACT
1. There is still a high incidence of tetanus neonatorum. An average admission of 40 cases a year was noted from 1960-1963 in the Southern Islands Hospital2. Mortality rate used to be very high in this hospital. Prior to 1960, it was almost 100. From 1960-1962 mortality rate decreased to 70-753. The rationale of treatment is discussed with emphasis on the necessity of a direct I.V. route for tetanus antitoxin4. Forty-nine cases of tetanus neonatorum admitted in the Southern Islands Hospital from January 1963 to December 1963 were included in the study5. A survival rate of about 69.4 was noted in the study6. Higher mortality rate was noted on those with ages 5 days and below and those where treatment has been delayed over 12 hours from onset7. Cases given insufficient tetanus antitoxin may survive but with longer duration than those who received sufficient antitoxin8. Tetanus antitoxin serum of 40,000 - 80,000 units, with 40,000 - 60,000 given by direct I.V. and the rest by I.M. are sufficient for most of the severe and moderate severe cases, preferably given early at the onset of symptoms to prevent fixation of lethal amounts of toxins in the central nervous system. (Summary and Conclusions)