Compliance of the total respiratory system in healthy preterm and full-term newborns.

The compliance of the total respiratory system (CRS) was determined by the occlusion technique during expiration in 19 preterm newborns (NB) over 31 weeks of gestational age (mean, 34 +/- 1.5 SD) and in 20 full-term NB. Postnatal age ranged from 1 to 28 days. No sedation was used during the test. In absolute terms, CRS was significantly greater (P less than 0.01) in full-term than in preterm NB (3.17 +/- 0.71 ml/cm H2O vs 2.37 +/- 0.81 ml/cm H2O). When normalized for body weight, length cubed, [corrected] body surface area, and the Quetelet index (body weight/length squared) [corrected], CRS was similar in preterm and full-term NB. These results suggest that, normalized for biometric data, passive elastic properties of the total respiratory system are similar in full-term and preterm NB, at least in the gestation age range studied.

Passive total respiratory system compliance and gas exchange in newborns with hyaline membrane disease.

Passive total respiratory system compliance (CRS) and gas exchange measurements were performed in nine newborns during the course of hyaline membrane disease. None of the subjects presented bronchopulmonary dysplasia at follow-up investigations. Gestational age ranged from 29 to 37 weeks. CRS was measured by the multiple occlusion technique. Gas exchange parameters were the fraction of inspired oxygen concentration (FIO2) and the arterial/alveolar ratio for oxygen (a/AO2 ratio). In each subject four tests were performed: test 1 during the first day of life; test 2 during the second day of life; test 3 between the fourth and the seventh days of life; test 4 after extubation. CRS/BW (CRS normalized for body weight) was not statistically different at tests 1-3, but it significantly increased (P less than 0.001) between tests 3 and 4. FIO2 and a/AO2 ratio presented no statistical difference at tests 1-2 but several significant differences were noted thereafter: FIO2 decreased significantly (P less than 0.001) when results from tests 2 and 3 were tabulated. The a/AO2 ratio increased significantly between tests 2 and 3 (P less than 0.001), and a further significant increase (P less than 0.01) was also noted when results obtained during tests 3 and 4 were compared. A significant relationship existed during the evolution of the disease between CRS/BW and gas exchange parameters (FIO2 and a/AO2 ratio) (P less than 0.01), but gas exchange improved earlier than lung mechanics.

[Orthotopic liver transplant in rats. Surgical technique, complications and treatment]. / Trasplante hepàtico ortotòpico en ratas. Técnica quirúrgica, complicaciones y sus tratamientos.

The orthotopic rat liver transplant model is a widely used technique in transplantation research. It has many advantages over other animal transplant models because of its availability and low cost. However, it must be emphasized that success with the rat model requires thorough training. The aim of this paper is to describe the microsurgical technique involved in 60 rat liver transplants and to discuss the complications and their treatments. Forty-nine liver transplants were performed at the Experimental Laboratory of the University Hospital, Ontario, Canada (ELUH) and 11 were performed at the Laboratorio de Trasplante de Organos de la Facultad de Ciencias Médicas de La Plata, Buenos Aires. Argentina (LTO). Among the transplants performed at the ELUH, the observed complications were haemorrhage (n = 4), pneumothorax (n = 1), anastomotic failure (n = 15), bile leak (n = 3), and bile duct necrosis (n = 9). The remaining 17 rats at the ELUH were healthy at day 7 after surgery. Animal survival immediately postop, at 24 hours postop and at 7 days postop was achieved with the 9th, 20th and 21st transplants respectively. At the LTO, 3 rats died as a result of anaesthetic complications. Seven-day animal survival was achieved with the 11th transplant. We beleive that the description of the orthotopic rat liver transplantation technique, as well as the discussion regarding complications and their management, can be useful for researchers interested in performing liver transplantation in rats.

Use of cryopreserved rat arteries for microsurgical training.

Silastic tubes are used as training material for performing microvascular anastomoses. However, silastic texture differs from that of actual blood vessels. In the present work, we evaluate the use of preserved rat arterial segments for training in microvascular anastomoses. One-centimeter-long rat arterial segments were obtained from femoral, carotid, and abdominal arteries, preserved in cold saline solution, and frozen. Trainees performed microvascular anastomoses using the aforementioned material and answered questions about texture, consistency, and wall resistance to the needle, comparing preserved arterial wall and silastic tubes. They were also asked whether the arterial pedicles had a consistency and texture similar to normal vessels, and if they were a more reliable method for practicing microsurgery techniques than synthetic materials. They preferred frozen arterial pedicles over silastic tubes. We conclude that arterial cadaveric segments are a suitable biologic material for microsurgical training. Since they can be obtained from other experiments, this is an effective way to reduce the number of animals bred and sacrificed for teaching purposes.

Neonatal patterns of breathing after cesarean section with or without epidural fentanyl.

The pattern of breathing and lung mechanics were evaluated during the first 7 h of life in full-term healthy newborns delivered by cesarean section with bupivacaine epidural anesthesia, without (group 1) or with the addition of 100 micrograms of fentanyl (group 2). Respiration and oxyhemoglobin saturation (SpO2) were measured with calibrated inductive plethysmography and pulse oximetry, respectively, and recorded from 60-420 min following birth. Compliance of respiratory system (CRS) was measured using a multiple occlusion technique at 60 and 420 min. Pattern of breathing was compared during period I (60-240 min) and II (240-420 min) with the following results: 1) the number of apnea spells was similar in both groups during both periods; 2) in both groups, from period I to period II a significant decrease in apnea duration was observed (7.6 +/- 0.7 s-4.1 +/- 0.5 s in group 1 and 6.7 +/- 1.2 s-5.1 +/- 1.0 s in group 2, respectively (P less than 0.05); 3) respiratory rate (RR) and minute ventilation (VE) were similar in both groups during both study periods; and 4) both RR and VE significantly decreased in the two groups from period I to period II (i.e., 59 +/- 5-46 +/- 2 breath per min-1 and 313 +/- 60-248 +/- 24 ml.kg-1.min-1 in group 1, and 60 +/- 2-51 +/- 1 breath.min-1 and 318 +/- 12-290 +/- 12 ml.kg-1.min-1 in group 2, respectively; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Esophageal reflux in symptomatic and asymptomatic infants: postprandial and circadian variations.

Twenty-two full-term infants, nine asymptomatic and 13 symptomatic for chronic digestive problems, had long-term (mean = 21 h) esophageal pH monitoring. All children were observed in strictly standardized conditions including meals and body position. Symptomatic infants presented significantly more esophageal refluxes, spent a greater percentage of time with a pH below 4, had a longer reflux duration (longer clearing time) and presented more refluxes lasting more than 5 min. We performed a determination of the circadian variations of parameters associated with esophageal reflux. Asymptomatic and symptomatic infants presented significant circadian variations of the percentage of time below pH 4 and of the longest duration of reflux. However, symptomatic infants had significantly higher mean values and increased amplitudes of circadian rhythms. Moderate phase lag existed for certain variables between symptomatic and asymptomatic infants. These findings can be helpful when interpreting the results of long-term esophageal pH monitoring.

Passive compliance of total respiratory system in preterm newborn infants with respiratory distress syndrome.

The passive compliance of the total respiratory system (CRS) was measured by the occlusion technique in 34 preterm newborn infants with respiratory distress syndrome. Gestational age ranged from 27 to 33 weeks. Preterm newborn infants were divided into four groups on the basis of clinical criteria. Group 1 consisted of 10 infants tested during the first postnatal days (1 to 3 days) while acutely ill and requiring ventilation and oxygen therapy. After the acute phase of respiratory distress syndrome, two groups were tested: group 2 consisted of nine infants (5 to 22 days of age) who no longer required ventilation, and group 3 consisted of six infants (7 to 28 days of age) who subsequently had bronchopulmonary dysplasia. Group 4 consisted of nine infants older than 1 month of age with confirmed bronchopulmonary dysplasia. Group 1 had significantly lower CRS and CRS normalized for body weight (CRS/BW) than group 2 had (P less than 0.001). In groups 3 and 4 CRS was significantly lower than in group 2 (P less than 0.001), as was CRS/BW (P less than 0.001). There was no significant difference in CRS and CRS/BW values between groups 3 and 4. This cross-sectional study in preterm infants with respiratory distress syndrome suggests that CRS may have predictive value in regard to development of bronchopulmonary dysplasia after the acute phase of respiratory distress syndrome.

[Passive compliance of the total respiratory system in newborn infants born by cesarean section]. / Compliance passive du système respiratoire total chez des nouveau-nés nés par césarienne.

The compliance of the total respiratory system (CRS) was measured by the occlusion technique: a) at H1-H2, H6-H7 and D3-D4 in 8 full-term newborns after cesarean section; b) at H1-H2 and H6-H7 in 6 full-term newborns delivered vaginally and at D3-D4 in 10 full-term newborns delivered vaginally. At H1-H2 respiratory frequency measured by inductive plethysmography was not significantly different between newborns after cesarean section (60 +/- 6 c/min) and newborns delivered vaginally (53 +/- 16 c/min). CRS normalized for body weight was not significantly different between newborns after cesarean section and those delivered vaginally at H1-H2 (0.6 +/- 0.1 vs 0.7 +/- 0.1 ml/cmH2O/kg) and at H6-H7 (0.7 +/- 0.1 vs 0.8 +/- 0.3 ml/cmH2O/kg). At D3-D4, CRS was significantly greater than at H6-H7 in newborns after cesarean section (1.1 +/- 0.2 ml/cmH2O/kg, p less than 0.001) and in newborns delivered vaginally (1 +/- 0.1 ml/cmH2O/kg, p less than 0.02). We conclude that in newborns after cesarean section without tachypnea, the evolution in CRS is similar to that in newborns delivered vaginally.

[Comparison of arterial and transcutaneous oxygen partial pressure in infants with bronchopulmonary dysplasia]. / Comparaison des pressions partielles artérielle et transcutanée en oxygène chez des nourrissons atteints de dysplasie bronchopulmonaire.

Transcutaneous PO2 (PTCO2) (Radiometer electrode heated to 44 degrees C) was compared to arterial PO2 (PaO2) in 19 infants with bronchopulmonary dysplasia: 12 infants were tested once, at the mean postnatal age of 14 weeks (range 4-43 weeks), the other 7 infants were studied longitudinally from 5 weeks (range 2-8 weeks) to 12 weeks (range 6-18 weeks) of postnatal age. The protocol was standardized: measurement during behavioral stage 1, using a peripheral arterial line. Twenty-eight comparisons between PTCO2 and PaO2 were obtained. PTCO2 was significantly related to PaO2 [PTCO2 (mmHg) = 0.81 PaO2 + 5.2, r = 0.73, p less than 0.01]. The mean difference PTCO2 - PaO2 was -7.2 mmHg (range: -34.5 to + 33); in the studied age range the PTCO2 - PaO2 was not significantly related to postnatal age (r = -0.24; p greater than 0.1).

Trasplante hepático ortotápico en ratas. Técnica quirúrgica, complicaciones y sus tratamientos / Orthotopic liver transplantation in rats

The orthotopic rat liver transplant model is a widely used technique in transplantation research. It has many advantages over other animal transplant models because of its availability and low cost. However, it must be emphasized that success with the rat model requires thorough training. The aim of this paper is to describe the microsurgical technique involved in 60 rat liver transplants and to discuss the complications and their treatments. Forty-nine liver transplants were performed at the Experimental Laboratory of the University Hospital, Ontario, Canada (ELUH) and 11 were performed at the Laboratorio de Trasplante de Organos de la Facultad de Ciencias Medicas de La Plata, Buenos Aires. Argentina (LTO). Among the transplants performed at the ELUH, the observed complications were haemorrhage (n = 4), pneumothorax (n = 1), anastomotic failure (n = 15), bile leak (n = 3), and bile duct necrosis (n = 9). The remaining 17 rats at the ELUH were healthy at day 7 after surgery. Animal survival immediately postop, at 24 hours postop and at 7 days postop was achieved with the 9th, 20th and 21st transplants respectively. At the LTO, 3 rats died as a result of anaesthetic complications. Seven-day animal survival was achieved with the 11th transplant. We beleive that the description of the orthotopic rat liver transplantation technique, as well as the discussion regarding complications and their management, can be useful for researchers interested in performing liver transplantation in rats (AU)

Trasplante hepOtico ortotòpico en ratas. Técnica quirúrgica, complicaciones y sus tratamientos. / [Orthotopic liver transplant in rats. Surgical technique, complications and treatment]

The orthotopic rat liver transplant model is a widely used technique in transplantation research. It has many advantages over other animal transplant models because of its availability and low cost. However, it must be emphasized that success with the rat model requires thorough training. The aim of this paper is to describe the microsurgical technique involved in 60 rat liver transplants and to discuss the complications and their treatments. Forty-nine liver transplants were performed at the Experimental Laboratory of the University Hospital, Ontario, Canada (ELUH) and 11 were performed at the Laboratorio de Trasplante de Organos de la Facultad de Ciencias Médicas de La Plata, Buenos Aires. Argentina (LTO). Among the transplants performed at the ELUH, the observed complications were haemorrhage (n = 4), pneumothorax (n = 1), anastomotic failure (n = 15), bile leak (n = 3), and bile duct necrosis (n = 9). The remaining 17 rats at the ELUH were healthy at day 7 after surgery. Animal survival immediately postop, at 24 hours postop and at 7 days postop was achieved with the 9th, 20th and 21st transplants respectively. At the LTO, 3 rats died as a result of anaesthetic complications. Seven-day animal survival was achieved with the 11th transplant. We beleive that the description of the orthotopic rat liver transplantation technique, as well as the discussion regarding complications and their management, can be useful for researchers interested in performing liver transplantation in rats.

Trasplante hepático ortotápico en ratas. Técnica quirúrgica, complicaciones y sus tratamientos / Orthotopic liver transplantation in rats

The orthotopic rat liver transplant model is a widely used technique in transplantation research. It has many advantages over other animal transplant models because of its availability and low cost. However, it must be emphasized that success with the rat model requires thorough training. The aim of this paper is to describe the microsurgical technique involved in 60 rat liver transplants and to discuss the complications and their treatments. Forty-nine liver transplants were performed at the Experimental Laboratory of the University Hospital, Ontario, Canada (ELUH) and 11 were performed at the Laboratorio de Trasplante de Organos de la Facultad de Ciencias Medicas de La Plata, Buenos Aires. Argentina (LTO). Among the transplants performed at the ELUH, the observed complications were haemorrhage (n = 4), pneumothorax (n = 1), anastomotic failure (n = 15), bile leak (n = 3), and bile duct necrosis (n = 9). The remaining 17 rats at the ELUH were healthy at day 7 after surgery. Animal survival immediately postop, at 24 hours postop and at 7 days postop was achieved with the 9th, 20th and 21st transplants respectively. At the LTO, 3 rats died as a result of anaesthetic complications. Seven-day animal survival was achieved with the 11th transplant. We beleive that the description of the orthotopic rat liver transplantation technique, as well as the discussion regarding complications and their management, can be useful for researchers interested in performing liver transplantation in rats

Modelo ex-vivo de lesión por isquemia y reperfusión en hígado de rata / Model ex-vivo of lesion for ischemia and reperfusion in rat liver

Introducción: desde la ablación al implante, múltiples factores influyen en la buena evolución del injerto hepático. De todos ellos, la lesión por isquemia y reperfusión es determinante de lesiones tisulares que llevan a la disfunción inicial del injerto o a la no función del mismo. El presente trabajo tiene por objetivo el mostrar la puesta a punto y funcionamiento de un modelo de isquemia y reperfusión en hígado de rata aislado. Material y métodos: 14 ratas Sprague-Dawley adultas fueron divididas en 2 grupos: en el primer grupo, isquemia (I), (n=6), luego de la hepatectomía el hígado fue preservado en solución en EuroCollins durante 1 horas. En el segundo (reperfusión, R), (n=8), los hígados ablacionados y preservados igual que en I fueron luego reperfundidos durante una hora con solución Krebs-Henseleit oxigenada y calentada a 37ºC. En R se tomaron muestras de la solución a los 10 y 60 minutos de comenzada la reperfusión para determinar concentraciones de Ca++, TGO, TGP, LDH y PO. Todos los hígados fueron perfundidos con Trypan Blue (TB) por 10 minutos y finalmente se tomó una bio

Modelo ex-vivo de lesión por isquemia y reperfusión en hígado de rata / Model ex-vivo of lesion for ischemia and reperfusion in rat liver

Introducción: desde la ablación al implante, múltiples factores influyen en la buena evolución del injerto hepático. De todos ellos, la lesión por isquemia y reperfusión es determinante de lesiones tisulares que llevan a la disfunción inicial del injerto o a la no función del mismo. El presente trabajo tiene por objetivo el mostrar la puesta a punto y funcionamiento de un modelo de isquemia y reperfusión en hígado de rata aislado. Material y métodos: 14 ratas Sprague-Dawley adultas fueron divididas en 2 grupos: en el primer grupo, isquemia (I), (n=6), luego de la hepatectomía el hígado fue preservado en solución en EuroCollins durante 1 horas. En el segundo (reperfusión, R), (n=8), los hígados ablacionados y preservados igual que en I fueron luego reperfundidos durante una hora con solución Krebs-Henseleit oxigenada y calentada a 37ºC. En R se tomaron muestras de la solución a los 10 y 60 minutos de comenzada la reperfusión para determinar concentraciones de Ca++, TGO, TGP, LDH y PO. Todos los hígados fueron perfundidos con Trypan Blue (TB) por 10 minutos y finalmente se tomó una biopsia de cada uno de los lóbulos hepáticos. Los cortes fueron tenido con Eosina y el porcentaje de núcleos teñidos con TB fue detrminado para cada grupo. Resultados: el procentaje de células teñidas con TB en el grupo I fue de 0,2 por ciento ñ 0,3 por ciento, mientras que el grupo R fue de 7,1 por ciento ñ 8,3 por ciento (p<0,01). La concentración de Ca++ en la solución de Krebs descendió en forma significativa a los 10 minutos de la reperfusión (p<0,001).