Pediatrics residents need to receive additional education in performing the calculations needed to prescribe medications. In addition, residents should be required to demonstrate these necessary mathematical skills before they are allowed to prescribe medications.
There are significant gender differences in ventilation, gas exchange, and anesthetic requirements in rats subjected to critical care conditions. The gas-exchange values observed in these spontaneously breathing rats may represent the optimal levels attainable during pentobarbital anesthesia with normal lungs. They may serve as standards for ventilator settings in the rat models used for critical care studies.
To measure insensible fluid loss from silicone membrane oxygenators during extracorporeal membrane oxygenation (ECMO), an in vitro system was used. A standard neonatal ECMO circuit (Avecor) was connected to a noncompliant reservoir, which was then primed with normal saline. The experiment was conducted by using two silicone oxygenators (Avecor 0.4 and 0.8 m2), three gas flow rates (0.5, 1.0, and 2.0 L/min) (sweep), and two fluid flow rates (200 and 400 ml/min). Two methods were used to measure the water loss. One method was to replace the water to the noncompliant circuit by using a calibrated burette, and the other method was to collect condensed water after cooling the postmembrane sweep gas to 0 degrees C. The influence of the amount of sweep, fluid flow rate, size of membrane, and inlet and outlet sweep gas temperatures on measured water loss was statistically determined. The amount of water loss correlated with sweep (r2 = 0.81; p<0.00001) but was not related to the fluid flow rate, membrane size, or inlet and outlet sweep gas temperature. The average daily fluid loss measured with replacement and collection methods for each liter of sweep per minute were 72.0+/-12.6 and 62.3+/-10.0 ml, respectively. This information may be applied to clinical practice to accurately manage fluid balance in the sick neonate on ECMO.
We studied levels of superoxide dismutase, glutathione, reductase, glutathione peroxidase and lipoperoxides in 12 healthy lambs below 1 year of age (8-19 kg) under therapy with extracorporeal membrane oxygenation (ECMO). Plasma levels of these free oxygen radical scavenging enzymes and lipoperoxides were taken 1 day before the ECMO experiment, at the beginning of ECMO after the first rotations of the roler pump, during, and after ECMO. The pre-ECMO results of days 1 and 2 were compared with the during-ECMO results and those with the post-ECMO results using the t test for paired samples. We found a significant decrease of both superoxide dismutase and glutathione reductase on ECMO, a trend to increased lipoperoxide levels, and unchanged levels of glutathione peroxidase. After discontinuing bypass the levels began to normalize again. We conclude that ECMO reduces some oxygen radical scavenging enzyme levels and exhibits a trend to increased lipoperoxide levels. Near total lung collapse with consecutive reperfusion injury might be harmful considering these results. However, the nonsignificant increase in lipoperoxide levels excludes considerable oxygen toxicity during this short ECMO trial.
Aiming at a better understanding of the pathophysiologic basis of perinatal encephalopathy, we evaluated patterns of tissue oxygenation during hypoxia and hyperoxia. We utilized both laserspectroscopy and invasive tissue-Po2 microneed measurements synchronously in five newborn lambs (141-143 days of gestation). The model of artificial placentation provided defined changes of the blood gases, using a extracorporeal circuit with interposition of membrane lung. During hyperoxia, the Po2 at the blood outlet port of the lung was raised to > 300 mmHg for five minutes. During hypoxia, Po2 was diminished as oxygen at the gas phasis was replaced by nitrogen. After the induction of hyperoxia, a rise of tissue-Po2 was observed. The synchronously recorded data of the laserspectroscopy showed adequately rising HbO2 values in concordance (r = 0.97, p < 0.001). As a constant finding we did not observe Cyt-aa3 changes during induced hyperoxia with tissue-Po2 values of < 40 mmHg. Furthermore, no changes in blood volume occurred in this case. A different pattern of the laserspectroscopic parameters was found when the tissue-Po2 rose above a value of > 40 mmHg and Cyt-aa3 rose after a lag-time occurred. During induced hypoxia an immediate fall of tissue-Po2 corresponding with a fall of HbO2 in the spectroscopic tracing occurred (r = 0.87, p < 0.001). A fall of the Cyt-aa3 level was seen with a lag-time when the tissue-Po2 had reached values of below 10 mmHg. In addition, a rise of blood volume was recorded in all cases of induced hypoxia. In conclusion, the results indicated that cellular redoxe state remains stable over a large range of oxygen partial pressure changes.
Healthy lambs are capable of maintaining effective cardiac output in the presence of moderate arteriovenous shunts (15%). AV-ECMO may provide efficient ventilatory support in the neonatal population with hypercapnia. The amount of oxygen delivery with AV-ECMO depends on arterial desaturation.
IntroductionPlasma COP is generated by the plasma proteins, particularly albumin, and is known to vary during various neonatal diseases [1][2][3][4]. Lower plasma COP favors a fluid shift from intravascular space into interstitial space, with subsequent formation of peripheral and pulmonary edema [3][4][5][6][7][8]. To stabilize the intravascular volume and prevent or reverse the events leading to peripheral and pulmonary edema, albumin or other colloid solutions are frequently administered, to maintain the COP in the 'normal' range [7][8][9][10][11][12]. Albumin administration for various conditions, however, is controversial [13][14][15]. Plasma COP in healthy neonates, sick neonates, and prematurely born infants are reported to be much lower than in adults [16][17][18]. The normal range of COP for healthy adults is reported to be between 22 and 28 mmHg, with a mean of 25 mmHg [19,20]. There is, however, no information in the literature on normal COP range beyond the early neonatal age. The adult COP values in our intensive care unit are also considered to be ANOVA = analysis of variance; COP = colloid osmotic pressure; SD = standard deviation. AbstractBackground The plasma colloid osmotic pressure (COP) plays a major role in transcapillary fluid balance. There is no information on plasma COP of healthy infants beyond the first post-natal week. The normal COP in healthy adult subjects (25 mmHg) is currently also applied as a reference value for healthy infants. This study was designed to test whether plasma COP values in healthy infants are the same as those in normal adults. Methods Plasma COP was measured in 37 male and female healthy infants from 1 to 11 months old. For this purpose, 1 ml blood was collected during the patient's regularly scheduled visit if the patient required any type of blood test for routine laboratory analyses. Results Plasma COP levels correlated slightly with increasing age from 1 to 9 months old (linear regression analysis; r 2 = 0.1, P < 0.049). We found no correlation between plasma COP and body weight at the same age (r 2 = 0.05, P = 0.155). The mean and standard deviation of COP in all infants was 25.1 ± 2.6 mmHg, which is almost identical to an average COP of 25 mmHg in healthy adult subjects. Arbitrary division of the infants into three different age groups (1-3 months [n = 11], 5-8 months [n = 13] and 9-11 months [n = 13]) showed an average increase of approximately 2 mmHg in COP of 9-month-old to 11-month-old infants, compared with 1-month-old to 3-month-old infants (one-way analysis of variance; P = 0.26). There was no gender difference in the COP level (unpaired t-test), with an average of 25.1 ± 2.4 mmHg in 19 male infants compared with 25.2 ± 2.9 in 18 female infants. The 95% confidence interval for COP in both male and female infants (n = 37) was between 24.3 to 26.0 mmHg, ranging from 19.5 to 30.3 mmHg, with a median value of 25.2 mmHg. Conclusions The data accept the null hypothesis that the COP range in infants younger than 1 year old is similar to those observed in ...
Mild hypothermia in rats, induced by a sustained pentobarbital anesthesia, reduces ventilation without compromising arterial oxygenation or acid-base balance, as measured at body temperature. Theoretically, our observations in spontaneously breathing rats imply that a combination of mild hypothermia with anesthesia could be safely utilized to maintain adequate ventilation, using relatively low minute ventilation. We speculate that such a maneuver, if applied during mechanical ventilation, may prevent secondary pulmonary damage by allowing the use of lower ventilator volume-pressure settings.
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