Ants Silberberg

The Physiologic Effects of Surfactant Treatment on Gas Exchange in Newborn Premature Infants with Hyaline Membrane Disease

ABSTRACT: To describe the physiologic effects of surfactant treatment on gas exchange in human premature infants with hyaline membrane disease, functional residual capacity (FRC), tidal volume (VT), the alveolar portion of tidal volume (VA), alveolar ventilation (VA), nitrogen clearance index, effective breath fraction calculated as VA/VT, compliance of the respiratory system, and arterial oxygen and carbon dioxide tensions were measured in 17 patients before and 0.5, 2, and 6 h after the administration of a single dose of either a synthetic surfactant (SS), Exosurf (n = 10), or a bovine surfactant (BS), Survanta (n = 7). By 2 h, treatment with either BS or SS was followed by an increase in the arterial/alveolar ratio of Po2 (a/A) and in FRC (p < 0.01 for both a/A and FRC). The a/A and FRC improved sooner (p < 0.001) and to a greater extent (p < 0.01) after BS than after SS. Compliance of the respiratory system and VT were decreased after either BS or SS at 0.5 h (p < 0.01) and remained decreased after SS at 2 h (p < 0.01). There was no significant change in VA or VA after either BS or SS. Because FRC and a/A increased without an accompanying increase in VA, VA, or compliance of the respiratory system, we believe that the immediate increase in FRC in this study was caused by stabilization of gas exchange units already being ventilated in addition to recruitment of new units. Nitrogen clearance index decreased and effective breath fraction increased after treatment, indicating an improved efficiency in gas mixing also thought to result from stabilization and maintenance of patency of distal airways by surfactant.

Immediate Effects on Lung Function of Instilled Human Surfactant in Mechanically Ventilated Newborn Infants with IRDS

ABSTRACT. We have studied the effects on lung volume, respiratory mechanics and ventilation during the first hours after instillation of 60 mg/kg of human surfactant into the trachea of 4 very preterm, newborn infants with severe IRDS under mechanical ventilation. Measurements were made with a “face‐out” body plethysmograph and a modified nitrogen wash‐out method. In addition to a transient decrease in total and alveolar ventilation immediately after the instillation we found an immediate rise in lung volume, but respiratory compliance decreased. These changes lasted less than two hours. Oxygen requirements fell in 3 out of 4 infants. The changes in lung volume and compliance are explained in terms of changes in the shape of the static recoil pressure characteristics of the diseased lungs after treatment. Mechanisms behind the short duration are sought in mode of instillation, dosage, age at treatment, and severity of disease.

Lung Volume, Gas Mixing, and Mechanics of Breathing in Mechanically Ventilated Very Low Birth Weight Infants with Idiopathic Respiratory Distress Syndrome

ABSTRACT: We assessed pulmonary function in 14 mechanically ventilated newborn very low birth weight infants with idiopathic respiratory distress syndrome by means of a face-out, volume displacement body plethysmograph and nitrogen washout analyses. Specially designed computer programs were used for calculations of lung volumes, ventilation, gas mixing efficiency, and mechanical parameters. In addition to very low compliance and moderately elevated resistance of the respiratory system, there were considerably impaired gas mixing efficiency and low functional residual capacity (FRC). No correlations between positive end-expiratory pressure and mean airway pressure versus compliance, resistance, or FRC could be found. Neither could correlations be found between FRC and compliance or FRC and the calculated right to left shunt.

A plethysmographic method for assessment of lung function in mechanically ventilated very low birth weight infants.

ABSTRACT: We have developed and tested a plethysmographic method for assessment of lung function in mechanically ventilated very low birth weight infants during intensive care. Information about the mechanics of the respiratory system is obtained from the respiratory flow as measured by volume displacement plethysmography and from airway pressure measured in the artificial airway. Data on lung volumes, ventilation, and distribution of ventilation is obtained simultaneously by combining the respiratory flow measurements with nitrogen concentration analyses of the respiratory gas. No significant differences were found when the estimations of mechanical parameters and FRC were compared with reference methods and when determinations of the same parameters were repeated in the same subjects. The plethysmograph was shown to be safe and convenient to use, even in studies lasting several hours.

Surfactant Improves Gas Mixing and Alveolar Ventilation in Preterm Lambs

ABSTRACT: Prophylactic treatment with ovine surfactant was evaluated in preterm lambs at risk for development of hyaline membrane disease. Eight mechanically ventilated newborn lambs were treated before delivery and 10 served as controls (gestational age 129–131 d). Lung mechanics, functional residual capacity, alveolar ventilation, efficiency of ventilation, and distribution of ventilation were tested using pressure, flow, and nitrogen elimination (nitrogen washout during 100% oxygen breathing) measurements in the endotracheal tube. The surfactant-treated animals showed significantly improved gas mixing efficiency in the lung with improved alveolar ventilation. Single exponential washout pattern dominated in both groups. Adequate functional residual capacity was established earlier after birth in the treated lambs than in the control animals. Lung mechanics in the treated group showed significant improvement in dynamic lung compliance. Surfactant treatment also improved gas exchange and reduced respirator pressure requirement. We speculate that the main functional effect of surfactant treatment in preterm lambs at risk to develop hyaline membrane disease is to maintain the patency of the peripheral airways in the lung, which improves diffusive gas mixing, alveolar ventilation, and gas exchange. The techniques used in this study should also be useful to evaluate lung function in preterm human infants after specific adaptation of the equipment size.

Exploring the feasibility of eHealth solutions to decrease delays in maternal healthcare in remote communities of Ghana

BackgroundDespite the introduction of the Millennium Development Goal to reduce maternal deaths from 400 to 100 per 100,000 live births, the proportion of maternal deaths is still much higher in most developing countries like Ghana. Various interventions have been implemented in Ghana that focus on increasing skilled maternal care. These are especially needed in rural areas. EHealth has the potential to contribute to reducing the challenges in maternal healthcare (MHC) that poor areas suffer. This paper analyzes the potential of eHealth solutions to improve maternal health in rural Ghana as well as the challenges to their implementation. The work was carried out in cooperation with the local health directorate of Kpando Municipality, one of the administrative areas in the Volta Region.MethodsThe study is focused on remote peninsulas and islands in Kpando Municipality. Data was gathered through triangulated research methods. Maternal health challenges were identified using the Three Delays Model for MHC. The three delays are delay in seeking care, delay accessing health facilities, and delay receiving adequate care. Challenges to the implementation of eHealth solutions in remote communities were analyzed using the Drury’s 5C eHealth model for developing countries. The 5Cs correspond to context, community, capacity, connectivity, and content.ResultsThe results show that financial dependence of women, a decision-making process based on previous experiences and traditional beliefs, competitiveness between facilities, organizational loopholes, lack of equipment, and geographical situations directly influence MHC outcomes. EHealth solutions, thanks to the high number of health workers with basic IT skills, have high potential to reduce MHC delays. However, poverty, cultural beliefs, organizational issues, connectivity, and lack of human resources were identified as main challenges to the implementation of eHealth solutions.ConclusionIn Ghana’s rural areas the three delays proposed in the model affect the outcomes of MHC. These delays are influenced by socio-economic status, access to facilities, and quality of care. EHealth solutions show great potential to reduce the delays. Based on the 5C model, a mHealth solution aiming to improve guidance during pregnancy was outlined.

Direct measurement of airway pressure in ventilated very low birth weight infants

A new method for direct measurement of airway pressure using a fiber optic pressure sensor (FOPS) has been tested in very low birth weight infants during mechanical ventilation. Airway pressure and ventilatory flow was recorded in an initial investigation in three newborn infants with a birth weight less than 1000 g. The method for direct measurement of airway pressure was found to be feasible in ventilated infants and can form a basis for reliable measurements which can be used to derive information on lung function and to guide in finding an effective ventilator management

Respiratory System Mechanics In Ventilated Infants: Effects Of Alveolar Gas Compression

A single compartment model has been used to describe the dynamic respiratory mechanics in 21 newborn infants. The subjects were intubated and studied during mechanical ventilation. A whole-body plethysmograph was used to record the ventilatory flow. The estimated resistance and compliance values of the respiratory system have been compensated for the effect of alveolar gas compression. The average compensated resistance value was 11% lower than the uncompensated value and the average compensated compliance value was 6% higher than the uncompensated value.

Recursive estimation of lung mechanical parameters in newborn infants during mechanical ventilation

A single-compartment lung model has been used to describe the dynamic pulmonary mechanical function in seven newborn infants. The subjects had low birth weights, less than 1500 g, and were studied under intermittent positive pressure ventilation. Linear regression techniques were used to calculate two lung model parameters, compliance (C) and resistance (R), for single breaths. The main interest has been to describe how the C and R parameter values vary within single breaths. A recursive linear regression technique was found to detect parameter value changes well.<<ETX>>

Estimation of changes of mechanical parameters in ventilated newborn children as a result of altered ventilator settings

A single-compartment lung model has been used to describe the dynamic pulmonary mechanical function in six intubated and ventilated newborn infants with a birth weight less than 1500 grams. Two model parameters, resistance and compliance, were used and derived for single breaths using a linear regression technique. Parameter values were calculated for whole breaths, the inspiratory phase and the expiratory phase. The main objective has been to detect any significant changes of the elastic and resistive properties of the respiratory system related to different ventilator settings. The estimated resistance and compliance parameter values changed significantly in 13 out of 15 cases.<<ETX>>