Study on hypocarbia in newborns during mechanical ventilation / 中华围产医学杂志

Objective To explore the causes and adverse effects of hypocarbia in newborns during mechanical ventilation. Methods Two hundred and forty-six newborns received assisted ventilation from Jan. 1994 to Dec. 2003 were retrospectively reviewed. Results The morbidity of hypocarbia was 14. 2%. It is common in preterm infants and the onset time of which were (31. 6?26. 9) hours after mechanical ventilation. The common primary disease was respiratory distress syndrome (RDS) (22. 6%). The mortality (32. 9%) and incidence of intracranial hemorrhage (20%) in hypocarbia cases were higher than those of the control group (7. 1 % and 5. 7%) (P

The Relation between Hypocarbia and Periventricular Leukomalacia in Preterm Infants with Mechanical Ventilation

PURPOSE: To investigate whether hypocarbia during the first 3 days of life plays a role in the development of periventricular leukomalacia (PVL) in preterm infants with mechanical ventilation. METHODS: The medical records were reviewed for 19 infants with PVL and 38 with normal neurosonogram who were born before 37 weeks' gestation and who required mechanical ventilation during the first 3 days of life. The patients' characteristics, antenatal and neonatal variables were compared. The CO2 index, TA (time-averaged)-PaCO2, TA-PaO2 and TA-pH were calculated within the first 72 hours of life. The TA-FiO2, TA-respiratory rate (RR), TA-peak inspiratory pressure (PIP), TA-mean airway pressure (MAP) and TA-ventilator index (VI) were also calculated. RESULTS: No significant difference was observed in the clinical characteristics or neonatal variables except hyaline membrane disease (42% in PVL group vs 81% in control group)(P=0.0025). There were no significant differences in CO2 index, TA-PaCO2 and TA- PaO2 between groups. The TA-pH was lower in infants with PVL (7.33+/-0.06) than in control group (7.37+/-0.05) (P=0.035). The TA-FiO2, TA-RR, TA-PIP, TA-MAP and TA- VI of two groups showed no significant differences. CONCLUSION: Partial pressure of arterial carbon dioxide during the first 3 days of life was not associated with the subsequent development of PVL. The compound effects of other risk factors including systemic pH may be important in the development of PVL in preterm infants.

The Relation between Hypocarbia and Periventricular Leukomalacia in Preterm Infants with Mechanical Ventilation

PURPOSE: To investigate whether hypocarbia during the first 3 days of life plays a role in the development of periventricular leukomalacia (PVL) in preterm infants with mechanical ventilation. METHODS: The medical records were reviewed for 19 infants with PVL and 38 with normal neurosonogram who were born before 37 weeks' gestation and who required mechanical ventilation during the first 3 days of life. The patients' characteristics, antenatal and neonatal variables were compared. The CO2 index, TA (time-averaged)-PaCO2, TA-PaO2 and TA-pH were calculated within the first 72 hours of life. The TA-FiO2, TA-respiratory rate (RR), TA-peak inspiratory pressure (PIP), TA-mean airway pressure (MAP) and TA-ventilator index (VI) were also calculated. RESULTS: No significant difference was observed in the clinical characteristics or neonatal variables except hyaline membrane disease (42% in PVL group vs 81% in control group)(P=0.0025). There were no significant differences in CO2 index, TA-PaCO2 and TA- PaO2 between groups. The TA-pH was lower in infants with PVL (7.33+/-0.06) than in control group (7.37+/-0.05) (P=0.035). The TA-FiO2, TA-RR, TA-PIP, TA-MAP and TA- VI of two groups showed no significant differences. CONCLUSION: Partial pressure of arterial carbon dioxide during the first 3 days of life was not associated with the subsequent development of PVL. The compound effects of other risk factors including systemic pH may be important in the development of PVL in preterm infants.

A Study on the Risk Factors of Periventricular Leukomalacia in Combined Use with Gentle Ventilation and High-Frequency Ventilation

PURPOSE: It is suggested that persistent hypocarbia caused by ventilator therapy could be a risk factor in PVL. The study is aimed to discover whether for preventing hypocarbia with combined use of gentle ventilation and high frequency ventilation, other factors would be causers of PVL. METHODS: Among 45 infants who were born and survived through ventilator treatment in the Fatima neonatal intensive care unit for four years from April 1996 to June 1999, 15 infants with PVL were classified as a study group and 30 without PVL as control group. The analysis was performed retrospectively with medical records. Ventilator treatment was based on the combined use of ventilation by means of the flow interruptor type of Infant Star . The aggressive weaning was performed when the clinical state, chest X-ray and arterial blood gas analysis became stabilized. RESULTS: Among 15 cases with PVL : 9 cases(60.0%) with fetal distress, 1 case(6.6%) with placenta previa, 1 case(6.6%) with placenta abruptio. In the relationship between PaCO2 variance on arterial blood gas analysis and PVL, the highest average of PaCO2 is 44.9 +/- 7.8 mmHg in the study group and 45.0 +/- 10.5 mmHg in the control group, which means there was not statistically significant difference. The PaCO2 concentration lower than 25 mmHg for three days appeared in one case in the study group. CONCLUSIONS: In cases of preventing hypocarbia by combined use of ventilation, it is suggested that the birth history and weaning method is important as risk factor of PVL.

Effects of the Level of PaCO2 on Recovery of Energy Metabolism: Is Normocarbia or Hypocarbia Better for Ischemia-Reperfused Cat Brain? / 대한마취과학회지

BACKGROUND: The effect of arterial carbon dioxide tension (PaCO2) during ischemia and reperfusion has been a controversial issue. In this study, the effect of PaCO2 during ischemia and reperfusion was evaluated by 31P magnetic resonance spectroscopy (MRS). METHODS: Incomplete global cerebral ischemia was induced by ligation of carotid artery under lowered mean blood pressure (mean blood pressure= 40 mmHg) for 30 minutes followed by 2 hours of reperfusion. Eighteen cats were divided into 3 groups: For group 1 (n=6) (control group), animals were subjected to normocarbia (PaCO2=28~33 mmHg) during ischemia and reperfusion, for group 2 (n=6), animals were subjected to hypocarbia (PaCO2=18~23 mmHg) during ischemia and reperfusion, and for group 3 (n=6), animals were subjected to normocarbia during ischemia and hypocarbia during reperfusion. RESULTS: For group 1, the energy metabolism measured by [PCr/Pi] was recovered about 74.7 6.4%. For group 2, the energy metabolism failed to be completely recovered by 120 minutes of reperfusion (69.3 7.3%), whereas for group 3, the energy matabolism was completely recovered by 120 minutes of reperfusion (97.6 2.4%). There were statistically significant differences between group 1 and group 3 (p<0.05). The changes in pH were not significantly different among the groups. CONCLUSION: In this study, a condition of hypocarbia during reperfusion seems better for the energy metabolism after incomplete global ischemia of cats.

Changes of Arterial Carbon Dioxide Tension Do Not Affect Respiratory System Mechanics in Enflurane Anesthetized Cats / 대한마취과학회지

BACKGROUND: Bronchoconstriction is known to be induced by hypocarbia or hypercarbia. But the above effect has not been studied during general anesthesia. This study was proposed to investigate the effects of hypocarbia and hypercarbia on the respiratory system mechanics in 0.5 MAC enflurane anesthetized cats. METHODS: Six cats, weighing 3.0~3.6 kg were used. Pentobarbital sodium was intraperitonially injected to induce anesthesia and endotracheal intubation was followed. The anesthesia was maintained by 0.5 MAC enflurane, oxygen, and air (FiO2; 0.5). Intermittent mandatory ventilation was applied with Siemens Servo 900C ventilator. The inspiratory flow rate and tidal volume were fixed througout the experiment. Only the respiratory rate was adjusted to achieve normocarbia(PaCO2; 31~38 mmHg), hypercarbia(PaCO2; 38~45 mmHg) and hypocarbia(PaCO2; 24~31 mmHg), which were done not in the order. We used the flow-interruption technique to measure respiratory mechanics. The course of changes in the pressure along with the prefixed flow rate and volume were monitored and recorded with Bicore CP100 pulmonary monitor. The data were transfered to a PC and analyzed by Anadat processing software. Total respiratory system, airway and tissue viscoelastic resistances, and dynamic and static compliances were calculated for normocarbia, hypercarbia and hypocarbia. RESULTS: There are no significant differences of resistances and compliances of respiratory system among hypocarbia, normocarbia and hypercarbia. CONCLUSIONS: The changes in PaCO2 do not influence significantly the resistances and compliances measured by the flow interruption technique used in the study.