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Biomedical subjects

T Gerhardt

Publications and source records attributed to T Gerhardt.

72 records · Page 4Linked to original sources
PubMed1980

Chestwall compliance in full-term and premature infants.

Chestwall compliance was determined in 26 premature infants (BW 1 320 +/- 410 g, gest. age 32 weeks) and in 10 full-term infants (BW 3 155 +/- 810 g) who were ventilated mechanically. Chestwall compliance in premature infants was 6.4 ml/(cmH2O X kg), decreasing with advancing gestational age to 4.2 ml/(cmH20 X kg) in full-term infants. There was a linear correlation (r = 0.95 and 0.79 respectively) between tidal volume and the pressure transmitted to the esophagus throughout the tidal volume range. The protion of airway pressure transmitted to the infants with hyaline membrane disease, 12% in newborns with a patent ductus arterisus, 17% in normal prematures and 25% in normal full-term infants. The findings suggest that during mechanical ventilation the high chestwall compliance and low lung compliance of premature infants prevent a significant rise in intrapleural pressure which could interfere with central venous return and cardiac output. However, using high inspiratory pressures and continuous distending airway pressure in the absence of lung pathology may result in a decreased cardiac output. The highly compliant chestwall of the premature infant may exert insufficient outward recoil and might be one of the causes of a low functional residual capacity and chronic pulmonary failure in the premature infant.

Compliance↗
PubMed1980

Lung compliance in newborns with patent ductus arteriosus before and after surgical ligation.

Pressure volume curves of the lungs were determined in 10 premature infants (mean gestational age 31.4 weeks, mean birth weight 1,260 g) before and after surgical ligation of a patent ductus arteriosus (PDA). 7 infants who had low compliance initially showed a significant improvement in lung compliance after surgery, while 3 infants whose compliance was close to normal before surgery had a decrease after ligation. In conclusion, a PDA with left to right shunt is frequently associated with a decrease in lung compliance that improves after ligation. Measurement of lung compliance in infants with PDA can be helpful in predicting the degree of improvement in lung function that may result from the closure of the ductus.

Ductus Arteriosus, Patent↗
PubMed1979

Hyaline membrane disease. Comparison of continuous negative pressure and nasal positive airway pressure in its treatment.

The effectiveness of continuous negative pressure (CNP) and nasal continuous positive airway pressure (CPAP) in the treatment of hyaline membrane disease and the incidence of complications were compared in 36 preterm infants randomly treated with CNP or nasal CPAP. Both methods of treatment were effective in increasing PaO2 and allowing a decrease in inspired O2 concentration. The time required with mechanical assistance and with an O2 concentration of more than 40% was equal in both groups. In the CNP group, four infants required mechanical ventilation because of clinical deterioration whereas in the nasal CPAP group, seven needed this type of therapy. Three infants in each group had extraalveolar air, and two patients in each group died. The results suggest that both methods of applying continuous distending airway pressure are effective. Nasal CPAP has the advantages of easier application and better access to the infant.

Blood Pressure↗
PubMed1978

Aminophylline therapy for idiopathic apnea in premature infants: effects on lung function.

The effect of aminophylline on lung function was studied in 14 premature infants with apnea (gestational age, 30.2 weeks; birth weight, 1.052 gm). The infants showed compromised pulmonary function with a large difference in alveolar-arterial PO2 gradient (83.9 mm Hg), a low normal lung compliance of 1.1 ml/cm H2O . kg, and a normal inspiratory resistance of 45.3 cm H2O/liter/sec. Aminophylline therapy did not change these functions significantly, but it decreased the incidence of apneic episodes from 29.7 to 4.4 per day. The effectiveness of aminophylline in treating apnea in premature infants must be related to its central stimulating effect and not to an improvement in lung function and oxygenation.

Aminophylline↗
PubMed1977

Respiratory depression at birth--value of Apgar score and ventilatory measurements in its detection.

The purpose of this investigation was to determine the value of ventilatory measurements and Apgar score in the diagnosis of respiratory depression in the newborn infant. The following were the results of the determinations made in 24 neonates whose mothers had received meperidine in a total dose up to 3 mg/kg within three hours prior to delivery; Respiratory rate, 51+/-3.7/minute; tidal volume, 21.4 +/- 1.5 ml; minute ventilation, 339 +/- 24 ml/kg X minute; end tidal CO2, 40.8 +/- 1.3 mm Hg; ventilatory response to CO2, 21.8 +/- 2.7 ML/KG X minute X mm Hg PACO2. The mean Apgar score was 7.1 and 9.0 at 1 and 5 minutes, respectively. None of the determinations were indicative of respiratory depression with the exception of the slope of the CO2 response curve; it was considered to be below the normal range. No correlations existed between the CO2 response curve and any other values. It is concluded that meperidine administered to mothers in labor in the described dose will not significantly alter Apgar score, VE, VT, RR, AND PAco2 in the newborn infant. The extent of respiratory center depression could be determined only by the decreased ventilatory response to CO2.

Apgar Score↗
PubMed1977

Use of nalotone to to reverse narcotic respiratory depression in the newborn infant.

Twenty neonates whose mothers had received meperidine (1.0 to 1.5 mg/kg) intravenously within three hours of delivery were studied to determine the effectiveness of naloxone in reversing neonatal respiratory depression. The following measurements were carried out within 20 to 30 minutes after delivery: minute ventilation, end tidal CO2, and ventilatory response to CO2. These determinations were repeated after administration of either placebo or naloxone, 0.01 mg/kg intramuscularly. Minute ventilation and PAco were within a normal range before medication in both groups, but the slope of the CO2 response curve was decreased, indicating mild-to-moderate respiratory depression. After administration of placebo the test results did not change significantly. After administration of naloxone, VE increased significantly (P less than 0.05) and the slope of the CO2 response curve doubled (P less than 0.001). Naloxone effectively reverses narcotic depression of the respiratory center in the newborn infant.

Carbon Dioxide↗
PubMedDate not supplied

Effect of a beta-agonist nebulization on lung function in neonates with increased pulmonary resistance.

Pulmonary resistance is elevated early in preterm infants who later develop chronic lung disease. This early increase in pulmonary resistance may play a role in the development of severe bronchopulmonary dysplasia (BPD). A beta-2-agonist (isoetharine HCl) was used as an aerosol in 13 preterm infants with elevated pulmonary resistance. Their birthweight ranged from 880 to 1630 g, their gestational age from 27 to 34 weeks, and their post natal age from 3 to 18 days. All infants had required mechanical ventilation for respiratory distress syndrome and therefore were at risk to develop BPD. Pulmonary mechanics were measured before and 30 minutes after aerosol treatment, determining inspiratory and expiratory flow with a pneumotachometer and esophageal pressure through a water-filled feeding tube. The treatment was well tolerated with no significant changes in blood pressure, heart rate, or respiratory rate. Pulmonary resistance decreased significantly from 130 +/- 35 cm H2O/L/sec to 89 +/- 24 cm H2O/L/sec after the treatment. Dynamic lung compliance increased in 11 of the 13 infants. It is concluded that beta-2-agonist nebulization is effective in reducing the early increase in pulmonary resistance that occurs in preterm infants who are at risk of developing BPD. This effect may be due to relaxation of bronchial smooth muscle, to improved mucociliary transport, and to a reduction in peribronchial edema.

Administration, Inhalation↗
PubMedDate not supplied

Pulmonary mechanics in normal infants and young children during first 5 years of life.

To characterize lung function in young children we measured lung compliance and pulmonary conductance in 40 normal infants and children ranging in age from the newborn period to 5 years. Inspiratory and expiratory flow was measured by a pneumotachograph, esophageal pressure through a water-filled feeding tube, and functional residual capacity (FRC) by a N2 washout technique. The esophageal pressure change per breath [(mean +/- SD) 7.3 +/- 1.4 cm H2O] and specific compliance (75 +/- 13 ml/cm H2O/L-FRC) did not change with growth. Specific conductance was high (0.60 L/s/cm H2O/L-FRC) in preterm infants, decreasing rapidly with initial growth but minimally beyond 10 kg of body weight, and stabilizing at 0.10 L/s/cm H2O/L-FRC. During the age period studied, compliance increased approximately x 25 whereas conductance only rose five-fold. The changes in compliance and conductance were well correlated to FRC, body weight, and length. These findings suggest that in the last trimester of pregnancy the airways are already well developed and postnatal lung growth occurs mainly by formation of new alveoli, leading to a proportional increase in FRC and lung compliance. Postnatally, conductance increases much more slowly than FRC, resulting in a rapid drop in specific conductance.

Airway Resistance↗
PubMedDate not supplied

Removal of amalgam, glass-ionomer cement and compomer restorations: changes in cavity dimensions and duration of the procedure.

This study investigated changes in the dimensions of Class II cavities following the removal of amalgam, glass ionomer and compomer restorations. In 30 extracted caries-free human molars, preparation for 60 mesio-occlusal and occluso-distal cavities (two cavities per tooth) occurred. With a CEREC 3 laser triangulation sensor and software-based construction analysis, the dimensions of the cavities at seven defined sites were measured. The cavities were randomized into four groups. Group 1 was restored with Ketac-Fil glass-ionomer cement, Group 2 with amalgam and Group 3 with Compoglass F compomer. In Group 4, Compoglass F was used in combination with photochromic Tetric Flow Chroma as a cavity liner. The completed restorations were then removed using 2x magnification and the cavities were once again controlled using the laser system. The duration of the removal procedure was also recorded. Changes in cavity dimensions (depth, height and width) following removal of the restorations were significantly smaller in Groups 1 and 2. Groups 3 and 4 were characterized by a significant overextension of the cavities compared to Groups 1 and 2 in all three dimensions. Group 4, with Tetric Flow Chroma as a cavity liner, showed better results than Group 3, but this improvement was not statistically significant. The duration of the removal procedure was significantly shorter in Group 2 than in the other groups.

Compomers↗