Variation of inhaled nitric oxide concentration with the use of a phasic flow ventilator.
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Administration, Inhalation↗
Biomedical subjects
T Hoehn
Publications and source records attributed to T Hoehn.
Effect of inhaled nitric oxide on intrapulmonary right-to-left-shunting in two rabbit models of saline lavage induced surfactant deficiency and meconium instillation.
Marked hypoxia secondary to intrapulmonary right-to-left shunting is a characteristic of respiratory failure in human neonates and can sometimes be complicated by additional extrapulmonary right-to-left shunting. To investigate the effect of inhaled nitric oxide (iNO) on intrapulmonary shunting, two typical pulmonary diseases of the newborn (respiratory distress syndrome and meconium aspiration) were reproduced in 32 mechanically ventilated rabbits weighing approximately 2 kg each. After tracheotomy, catheters were inserted into a jugular vein, a carotid artery and the right ventricle (to measure systolic right ventricular pressure [SRVP] and mixed venous oxygen content for calculation of shunt by Fick equation). Repeated airway lavages (LAV) with normal saline or repeated instillations of a suspension of human meconium (MEC) were continued until both the a/A-ratio was < or =0.14 and a peak inspiratory pressure > or =22 mbar was needed to keep the tidal volume constant at 10 ml/kg of body weight. Measurements of shunt, SRVP, systolic systemic pressure, physiological dead space, tidal volume and a ventilation index were performed before and after completion of lung damage and at 20 and 60 min after administering iNO at 80 ppm. Four groups of rabbits were studied (n=8 in each group): LAV control and intervention, Mec control and intervention. 60 min after starting iNO, there was a decrease in shunt (LAV: 67.6%+/-[SD] 11.3% vs 56.2+/-16.4, P=0.05; MEC: 52.6+/-6.3 vs 44.3+/-8.3, P < 0.05), in SRVP (LAV: 29.7 mmHg +/-10.1 mmHg vs 20.0+/-8.2, P < 0.01; MEC: 25.1+/-4.4 vs 22.3+/-5.0, P=0.46) and in dead space (% of tidal volume, LAV: 32.7%+/-10.5% vs 25.9+/-10.1, P < 0.01; MEC: 26.1+/-16.6 vs 18.9+/-10.1, P=0.05). These results demonstrate that iNO decreases intrapulmonary shunt (as well as SRVP and dead space). We suggest that iNO may be beneficial in human newborns with severe respiratory failure even if no extrapulmonary shunting via ductus or foramen ovale is apparent.
Administration, Inhalation↗
Partial transsection of the neonatal trachea.
This report describes an unusual case of partial transsection of the neonatal trachea after intubation. Mucosal injury led to the formation of a balloon-shaped, air-filled cyst that did not allow ventilation of the airways either via a tracheal tube or with a face mask. Several minutes after death, the cyst had collapsed and bag and mask ventilation produced adequate chest movements.
Cardiopulmonary Resuscitation↗
Effect of therapeutic concentrations of nitric oxide on bacterial growth in vitro.
OBJECTIVES: Besides its vasodilative actions, nitric oxide (NO) is also involved in host defense on a cellular level. We studied the antimicrobial properties of NO in concentrations used with inhaled NO therapy for the treatment of pulmonary hypertension in neonates. DESIGN: In vitro study of bacterial growth of five species, with and without NO exposure. SETTING: Level IV neonatal intensive care unit at a university children's hospital. SUBJECTS: In vitro bacterial cultures. INTERVENTIONS: We tested ten different strains of five bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, group B streptococcus [GBS/Streptococcus agalactiae], Escherichia coli, and Pseudomonas aeruginosa), derived from the tracheal isolates of ventilated premature and term infants. Cultures were exposed to three different concentrations of NO (40, 80, and 120 parts per million [ppm]) and bacterial growth was compared with the same strains incubated in ambient air for 24 hrs. After incubation (with or without NO), colony-forming units were counted. MEASUREMENTS AND MAIN RESULTS: Bacterial growth of S. aureus, E. coli, and P. aeruginosa was not reduced with the NO concentrations applied. The number of colony-forming units of S. aureus increased at 80 ppm of NO. Growth of S. epidermidis and GBS was significantly affected at 120 ppm, resulting in decreased numbers of colony-forming units as compared with controls exposed to ambient air. CONCLUSIONS: We conclude that NO has a selective bacteriostatic effect on some of those bacteria most commonly cultured in tracheal specimens of premature infants and neonates. This effect appears to be dose-dependent and occurs in the upper range of dosages used with inhaled NO therapy. However, in the range of dosages applied in ongoing controlled trials of inhaled NO in neonates and premature infants (1 to 80 ppm), a bacteriostatic effect of NO is not to be expected.
Administration, Inhalation↗
Enhancement of surfactant effect by a mechanical volume recruitment maneuver depends on the lungs preexisting distension.
'Rescue' surfactant treatment of premature infants with respiratory distress syndrome (RDS) results in two mechanisms: stabilization of alveoli already being ventilated and recruitment of alveoli collapsed before surfactant administration. Mechanical recruitment of alveoli from this collapsed compartment might enhance the immediate effects of surfactant treatment. To test this hypothesis 15 mechanically ventilated young rabbits underwent repeated airway lavage with normal saline at a constant, positive end-expiratory pressure (PEEP) of 3 cm H2O until both the a/A ratio was < 0.12 and a peak inspiratory pressure (PIP) > 20 mbar was needed to keep the tidal volume (VT) at 10 ml/kg. Surfactant (Survanta) was given over 4 min in conjunction with a mechanical volume recruitment maneuver (VRM) which consisted of an increased PIP by 33% of baseline values. The effects of surfactant were assessed using two indices of gas exchange (a/A ratio and PaCO2), four indices of lung function (functional residual capacity, FRC, dynamic lung compliance, Crs, VT and the alveolar portion of VT) and postmortem pressure-volume curves and were compared with two groups of rabbits receiving surfactant alone or no surfactant at all. VRM yielded an increase in Crs by +22% whereas VT increased by +58% suggesting overdistension of terminal airways to some extent. There were no differences between the surfactant and the VRM + surfactant groups for all indices assessed after an observational period of 2 h following surfactant administration. In a previous model using a PEEP of 1 cm H2O [Krause et al., Am J Respir Crit Care Med 1997;156:862-866], significant differences have been disclosed for Crs, VT and FRC. In conclusion, the enhancement of surfactant effect by VRM largely depends on the preexisting distension of the lungs.
Animals↗
Treatment of respiratory failure with inhaled nitric oxide and high- frequency ventilation in an infant with respiratory syncytial virus pneumonia and bronchopulmonary dysplasia.
In a 7-month-old infant with bronchopulmonary dysplasia and respiratory syncytial virus (RSV) pneumonia, we have shown an additive effect of high-frequency ventilation (HFV) and inhaled nitric oxide (iNO) in terms of improved oxygenation and the avoidance of extracorporeal membrane oxygenation. Apparently, the combined therapy of HFV and iNO is superior to either therapeutic modality alone in the treatment of hypoxemic respiratory failure due to RSV pneumonia. The mechanism of increased lung expansion and alveolar recruitment appears to be responsible for a favorable clinical outcome. We conclude that the combined therapy of HFV and iNO should be considered in hypoxemic respiratory failure in pediatric patients.
Administration, Inhalation↗
High-frequency ventilation augments the effect of inhaled nitric oxide in persistent pulmonary hypertension of the newborn.
Does inhaled nitric oxide (iNO) during high-frequency ventilation (HFV) lead to a more pronounced improvement in oxygenation than iNO during conventional ventilation? We report two cases of newborn infants with profound hypoxaemia, who did not respond with an increase in arterial oxygenation following iNO therapy during conventional mechanical ventilation. The first infant was a term neonate with persistent pulmonary hypertension of the newborn (PPHN) following postnatal hypoxia, the second patient a premature infant of 29 weeks of gestation with PPHN secondary to lung hypoplasia and perinatal asphyxia. After the initial failure of iNO we switched both neonates to HFV without NO, which did not lead to a significant improvement of oxygenation in either case. Shortly after the initiation of HFV a second trial of iNO was started. Both infants responded favourably to iNO with a marked and sustained increase in arterial oxygenation and absent right-to-left shunting via the ductus arteriosus and the foramen ovale. We conclude that the favourable response to inhaled nitric oxide is dependent on the degree of lung expansion and is more readily achieved by the use of high-frequency ventilation than conventional ventilation.
Administration, Inhalation↗
Physiological, biochemical and subjective parameters in anxiety patients with panic disorder during stress exposure as compared with healthy controls.
Physiological (heart rate, blood pressure, electrodermal activity), biochemical (epinephrine, norepinephrine, cortisol) and subjective parameters (self-rating score) of 33 patients with panic disorder (diagnoses according to DSM-III-R) before, during and after stress exposure were compared with those of healthy controls. As stressors a video containing frightening scenes (FS), mental arithmetic (MA), a video documenting a patient suffering from a panic attack (PA) and an improvised speech (IS) were applied. We found significantly higher baseline levels of electrodermal activity (EDA) and norepinephrine (NE) secretion and a subsequent further increase during stress exposure in panic disorder patients as compared with normal controls. The most potent stressors during the trial proved to be mental arithmetics and improvised speech, which was evident in both groups. The situation panic attack video appeared to be a "panic disorder patient-specific" stressor; here we noticed the most pronounced reactions in the patient group. Panic disorder patients had significantly higher self-rating scores of the parameters panicky feelings, anxiety and nervousness at the beginning and throughout the investigation. We conclude that panic disorder patients have a higher degree of activation compared with normal controls, which is evident regarding levels of electrodermal activity and norepinephrine secretion. Furthermore, the panic attack video appears to be a panic disorder patient-specific stressor.
Adult↗
[Inhaled nitric oxide therapy in preterm infants].
According to a number of recently published, randomized controlled trials, treatment of persistent pulmonary hypertension of the newborn (PPHN) by the use of inhaled nitric oxide (iNO) has emerged as an established procedure in neonatology. The situation in premature infants appears to be more complicated than in the term infant. Due to the fact that nitric oxide interferes with platelet aggregation, the risk of intraventricular hemorrhage or its aggravation during iNO therapy is being discussed in a controversial manner. Since most studies are aimed at endpoints like oxygenation parameters, the presently available studies report extremely variable incidences of intraventricular hemorrhages (IVH). Meanwhile two large studies could demonstrate that clinical application of iNO in preterm infants is not associated with an increased incidence of IVH. Further randomized controlled trials of iNO in preterm neonates are highly desirable in order to establish the future role of this therapy and its indications.
Cerebral Hemorrhage↗
Meta-analysis of inhaled nitric oxide in premature infants: an update.
INTRODUCTION: The role of inhaled nitric oxide (iNO) in the treatment of severe hypoxemic respiratory failure of term neonates has been firmly established in several randomized trials. In contrast, the use of iNO in premature newborns has remained controversial. We performed a meta-analysis of five published randomized controlled trials involving a total of 808 infants below 34 weeks of gestation. RESULTS: The rates of major intracranial hemorrhage (ICH) were similar in both groups (42 of 208 infants receiving iNO vs 52 of 185 controls, relative risk (RR) 0.72, 95 % confidence interval (CI) 0.50-1.02) as was the mortality rate (169 of 415 receiving iNO vs 155 of 393 controls, RR 1.03, 95 % CI 0.87-1.22). Of 415 infants receiving iNO, 188 infants were diagnosed as having chronic lung disease (CLD), compared to 215 of 393 control infants. The RR in favor of iNO was 0.83, 95 % CI 0.72-0.95, p = 0.0092. Treatment failure, defined as death or CLD was significantly reduced in the iNO group (iNO: 126 of 208 infants versus control: 139 of 185, RR in favor of iNO 0.81, 95 % CI 0.70-0.93, p = 0.0025). CONCLUSIONS: We conclude that the use of iNO may decrease the CLD and the combined endpoint CLD and mortality in preterm infants with hypoxemic respiratory failure. However, the most recent and by far largest study was terminated due to an increase in severe ICH. Therefore a cautious use of iNO in preterm infants at risk for ICH is mandatory. Further studies with appropriate neurodevelopmental follow-up need to elucidate if the reduction of CLD in very low birth weight infants is potentially associated with modifications in neurodevelopmental outcome.
Administration, Inhalation↗
[Efficiency and risk of chest physiotherapy in the newborn--review of the literature].
Chest physiotherapy (CP) in the mechanically ventilated newborn infant belongs to standard treatment methods of neonatal intensive care units in many countries for more than twenty years. In the late seventies, some of the studies published were able to demonstrate a beneficial effect of CP on short time improvement of oxygenation in those newborns treated. Other trials dealt with the (patho)-physiologic changes e.g. in cerebral perfusion following routine nursery procedures such as positioning, suctioning and CP. Recent studies have shown that the mechanically ventilated preterm infant is at risk to suffer intracranial bleeding or a "postnatal encephaloclastic porencephaly" due to routine CP. Prospective randomized trials with large patient numbers are needed to prove an effect of CP on shortening mechanical ventilation in the newborn. Meanwhile CP should not be administered on a routine basis especially not in the preterm infant, but only after assessment of the individual risk-benefit-ratio.
Humans↗
[Reversal of a right-left shunt and permanent improvement of oxygenation by inhalation of nitrogen monoxide in a premature infant with lung hypoplasia and asphyxia].
We report the case of a 29 weeks gestation female premature infant who suffered from severe postnatal asphyxia following spontaneous vaginal delivery. Prenatally lung hypoplasia due to prematurely ruptured membranes with subsequent oligohydramnios was suspected sonographically. Echocardiography revealed right-to-left shunting via PDA and foramen ovale, in addition to that tricuspid incompetence with a pulmonary arterial pressure gradient of 40 mmHg was demonstrated. At an oxygenation index (OI) of 34, an arterio-alveolar oxygen difference (AaDO2) of 639 mmHg, an FiO2 of 1.0 and a maximal paO2 of 37 mmHg during high frequency ventilation (HFV), we applied inhaled nitric oxide (up to 70 ppm) for a duration of approximately 30 hours. Within two hours the inspiratory oxygen concentration could be weaned to an FiO2 of 0.21, mean airway pressures were reduced markedly. Echocardiographically tricuspid incompetence had disappeared, the PDA was closed and now left-to-right shunting across the foramen ovale was demonstrated. The infant was extubated on day 5 and subsequently had oxygen requirements up to an FiO2 of 0.3 during spontaneous breathing for 20 days.
Administration, Inhalation↗