Biomedical subjects

Peter C Rimensberger

Publications and source records attributed to Peter C Rimensberger.

16 recordsLinked to original sources

PubMed2006

Volume-targeted modes of modern neonatal ventilators: how stable is the delivered tidal volume?

OBJECTIVE: Volume-targeted modes are designed to deliver a constant tidal volume (V(t)) at lowest possible pressure independently of changes in compliance, resistance, and leak of the respiratory system. We examined whether these volume-targeted modes respond rapidly enough to sudden changes in respiratory mechanics (e.g., selective intubation, surfactant administration, endotracheal tube kinking, de-kinking, obstruction), resulting in insufficient or excessive V(t) delivery. DESIGN AND SETTING: Bench study of six neonatal ventilators in the volume-targeted mode simulating preterm and full-term infant settings on a test lung. MEASUREMENTS AND RESULTS: Breath-to-breath expiratory V(t) were measured after rapid compliance, resistance, and leak changes. Under our test settings all ventilators showed important volume overshooting following rapid increase in compliance or decrease in resistance. Between one and 16 inflations were required to return to the set V(t). Some ventilators delivered inaccurate V(t) under steady state condition while others showed considerable breath-to-breath V(t) variability. CONCLUSIONS: We observed inaccurate V(t) delivery under specific conditions as well as immediate and sometimes prolonged volume overshooting after a rapid respiratory system compliance increase or resistance decrease in volume-targeted modes of modern neonatal ventilators. Similar discrepancies between the set V(t) and the delivered inflations can be harmful in clinical situations, especially in newborns. Their clinical relevance needs to be clarified with safety studies in the neonatal population and we encourage manufacturers to further improve the ventilators algorithms.

Equipment Design↗

PubMed2006

Left ventricular epicardial VVI pacing for a congenital complete heart block with severe myocardial dysfunction: shall epicardial pacing wires be positioned left?

We present the case of a patient with a congenital complete heart block (CHB) who developed a severe dilated hypokinetic cardiomyopathy whilst paced with a right-sided epicardial wire inserted by an anterior approach. She dramatically and rapidly improved both clinically and echocardiographically, once a single pacing wire was inserted on the left ventricular (LV) wall towards the apex by left thoracotomy. Based upon recent literature, attention is drawn to the fact that left-inserted epicardial pacing wires should probably be considered for pediatric patients in whom atrio-ventricular or inter-ventricular pacing might not be possible to achieve, or else as a consistent approach for small patients requiring VVI epicardial pacing.

Cardiac Pacing, Artificial↗

PubMed2006

National ethical directives and practical aspects of forgoing life-sustaining treatment in newborn infants in a Swiss intensive care unit.

QUESTION UNDER STUDY: How do actual aspects of forgoing life supporting therapy (LST) in newborn infants compare with national ethical directives in a Swiss intensive care unit? METHODS: A prospective set of data on deaths after forgoing LST over a three year period in a single intensive care unit is analysed in view of the directives issued by the Swiss Academy for Medical Sciences (SAMS). RESULTS: Thirty-four newborn infants died after a decision to forgo LST, 21 after withdrawing and 13 after withholding. The decision making process was confined to the caregivers' team. Parents rarely initiated the discussion but participated in all decisions and were considered as willing in 32% and consenting in 68%. Futility was invoked in 79% of cases and poor developmental outcome in 21%. Respiratory support was forgone in 59%, circulatory support in 6% and both in 35%. The mother assisted the child at the time of death in 91%. At that time, 82% of infants were receiving opiates and 18% benzodiazepines, some in a higher than usual dose. Death occurred at a median of 13 (25-75% = 6-25) minutes after withdrawing LST and 70 (27.5-147.5) after withholding (p <0.001) without correlation with the dose of analgesic or sedative administered. None of these observations obviously departed from the Swiss ethical directives. CONCLUSIONS: Practices surrounding forgoing LST in newborn infants in a Swiss intensive care unit match ethical directives. Factors leading to occasional use of unusually high dose of analgesic and sedative drugs remain to be identified.

Decision Making↗

PubMed2006

Lung volume recruitment after surfactant administration modifies spatial distribution of ventilation.

RATIONALE: Although surfactant replacement therapy is an established treatment in infant respiratory distress syndrome, the optimum strategy for ventilatory management before, during, and after surfactant instillation remains to be elucidated. OBJECTIVES: To determine the effects of surfactant and lung volume recruitment on the distribution of regional lung ventilation. METHODS: Acute lung injury was induced in 16 newborn piglets by endotracheal lavage. Optimum positive end-expiratory pressure was identified after lung recruitment and surfactant was administered either at this pressure in the "open" lung or after disconnection of the endotracheal tube in the "closed" lung. An additional recruitment maneuver with subsequent optimum end-expiratory pressure finding was executed in eight animals; in the remaining eight animals, end-expiratory pressure was set at the same level as before surfactant without further recruitment. ("Open" and "closed" lung surfactant administration was evenly distributed in the groups.) Regional ventilation was assessed by electrical impedance tomography. MEASUREMENTS AND MAIN RESULTS: Impedance tomography data, airway pressure, flow, and arterial blood gases were acquired during baseline conditions, after induction of lung injury, after the first lung recruitment, and before as well as 10 and 60 min after surfactant administration. Significant shift in ventilation toward the dependent lung regions and less asymmetry in the right-to-left lung ventilation distribution occurred in the postsurfactant period when an additional recruitment maneuver was performed. Surfactant instillation in an "open" versus "closed" lung did not influence ventilation distribution in a major way. CONCLUSIONS: The spatial distribution of ventilation in the lavaged lung is modified by a recruitment maneuver performed after surfactant administration.

Animals↗

PubMed2006

Fatal GvHD as a complication of liver transplantation for undetermined fulminant hepatic failure and associated aplastic anemia.

Fulminant hepatic failure of unknown origin is the most common cause of fulminant hepatitis with high incidence of aplastic anaemia. Furthermore, the association of liver failure and aplastic anaemia has an increased mortality rate. In this report we describe a 16-month-old boy who presented with aplastic anaemia preceding a non-A, non-B, non-C fulminant liver failure. He developed severe graft versus host disease (GvHD) after liver transplantation, proven by the presence of donor cells in the peripheral blood and in the skin biopsy. He received conventional therapy (steroids, mycophenolate, anti-IL-2 monoclonal antibodies, anti-thymocyte globulin) without success. In an attempt to obtain T cell depletion and reduce the GvHD, he was treated with Alemtuzumab, a first time use for this indication. Aplastic anaemia was extensively investigated, especially exploring the possibility of primary immunodeficiency and reticular dysgenesis which were excluded based on clinical history. However, another form of primary immunodeficiency could be the cause of the uncontrollable proliferation of the donor lymphocytes derived from the liver transplant. Despite aggressive treatment GvHD progressed and the patient died of multiorgan failure. The majority of authors mention aplastic anaemia as a secondary event post liver transplant, whereas in our view this might be a haematopoietic stem cell disorder preceding fulminant hepatic failure. These patients also need to be evaluated extensively in order to exclude a primary immunodeficiency. The underlying disease will determine the choice of immunosuppressive treatment, especially in case of development of GvHD caused by the transplanted lymphocytes inhabiting the donor liver.

Anemia, Aplastic↗

PubMed2006

Intravenous adenosine for refractory pulmonary hypertension in a low-weight premature newborn: a potential new drug for rescue therapy.

OBJECTIVES: To use intravenous adenosine as a rescue therapy for neonatal refractory pulmonary hypertension in a low-weight premature infant. STUDY LINE: We report the successful use of a continuous intravenous adenosine infusion in a 1150-g premature baby with severe persistent pulmonary hypertension, refractory to classic management with high-frequency oscillatory ventilation, oxygen therapy and inhaled nitric oxide. RESULTS: Adenosine infusion had a dramatic effect allowing for a rapid weaning of oxygen, ventilatory variables, and nitric oxide. CONCLUSIONS: Although experience with continuous adenosine infusion is still at an early stage, it might be worth considering its administration as a rescue therapy or even as an alternative to extracorporeal membrane oxygenation.

Adenosine↗

PubMed2006

Allowing for spontaneous breathing during high-frequency oscillation: the key for final success?

In the present issue of Critical Care, van Heerde and colleagues describe a new technical development (a flow-demand system during high-frequency oscillation) that may have an important impact on the future use of high-frequency ventilation in children and adults. Flow compensation on patient demand seems to reduce the imposed work of breathing, may therefore increase patient comfort, and should theoretically allow for maintaining spontaneous breathing while heavy sedation and muscular paralysis could be avoided. With further technical development of this concept, high-frequency oscillation can finally be added to the techniques of mechanical ventilatory support that maintain, rather than suppress, spontaneous breathing efforts. Furthermore, this concept will give high-frequency oscillation the chance to prove its potential role as primary therapy in patients with acute lung injury/acute respiratory distress syndrome, the chance to reduce the incidence of high-frequency oscillation failure for patient or physician discomfort as reported in so many clinical trials in the past, the chance to most probably allow successful weaning from high-frequency oscillation to extubation, and, ultimately, in analogy to what has been reported from the experience with other ventilator modes that allow for maintaining spontaneous breathing, the chance to decrease ventilator days in patients with acute lung injury/acute respiratory distress syndrome.

High-Frequency Ventilation↗

PubMed2004

Acute hypoxic respiratory failure as the first manifestation of systemic-onset juvenile rheumatoid arthritis in a child.

Systemic onset juvenile rheumatoid arthritis is the most common rheumatologic disorder of childhood. Pleuropulmonary manifestations are rare in children in this multiorgan disease, and are usually not severe. The diagnosis of systemic onset juvenile rheumatoid arthritis is made by exclusion, in the presence of clinical findings constellation. We present the case of an 8-year-old girl who developed acute hypoxic respiratory failure as the first manifestation of systemic onset juvenile rheumatoid arthritis, then severe respiratory relapse 16 months later. Clinical and radiological improvement were achieved at both times after high dose pulse methylprednisolone therapy.

Acute Disease↗

PubMed2004

Extratracheal biodegradable splint to treat life-threatening tracheomalacia.

A 9-month-old girl presented with life-threatening acute respiratory failure 1 week after the surgical correction of a double aortic arch, which was due to a severe bulging of the pars membranacea into the lumen of the trachea that produced a complete obstruction of the lower trachea. Under cardiopulmonary bypass, a Y-shaped posterior biodegradable splint was placed behind the trachea and sutured to the posterior trachea, and a simultaneous right aortic arch aortopexy was performed. Thereafter, the child recovered normal respiratory function. Follow-up bronchoscopy showed a posterior dip at the splint level and an asymptomatic persistent posterior compression of the right main bronchus.

Absorbable Implants↗

PubMed2004

Aerosolized iloprost as a bridge to lung transplantation in a patient with cystic fibrosis and pulmonary hypertension.

We describe a patient with cystic fibrosis, end-stage lung disease, and secondary pulmonary hypertension in whom aerosolized iloprost was effective in lowering pulmonary artery pressure and improving functional status, thus proving successful as a bridge to lung transplantation. Inhaled iloprost may be an efficient and selective approach to treat pulmonary hypertension related to end-stage obstructive pulmonary disease.

Administration, Inhalation↗

PubMed2003

Electrical impedance tomography: a method for monitoring regional lung aeration and tidal volume distribution?

OBJECTIVE: To demonstrate the monitoring capacity of modern electrical impedance tomography (EIT) as an indicator of regional lung aeration and tidal volume distribution. DESIGN AND SETTING: Short-term ventilation experiment in an animal research laboratory. PATIENTS AND PARTICIPANTS: One newborn piglet (body weight: 2 kg). INTERVENTIONS: Surfactant depletion by repeated bronchoalveolar lavage, surfactant administration. MEASUREMENTS AND RESULTS: EIT scanning was performed at an acquisition rate of 13 images/s during two ventilatory manoeuvres performed before and after surfactant administration. During the scanning periods of 120 s the piglet was ventilated with a tidal volume of 10 ml/kg at positive end-expiratory pressures (PEEP) in the range of 0-30 cmH(2)O, increasing and decreasing in 5 cmH(2)O steps. Local changes in aeration and ventilation with PEEP were visualised by EIT scans showing the regional shifts in end-expiratory lung volume and distribution of tidal volume, respectively. In selected regions of interest EIT clearly identified the changes in local aeration and tidal volume distribution over time and after surfactant treatment as well as the differences between stepwise inflation and deflation. CONCLUSIONS: Our data indicate that modern EIT devices provide an assessment of regional lung aeration and tidal volume and allow evaluation of immediate effects of a change in ventilation or other therapeutic intervention. Future use of EIT in a clinical setting is expected to optimise the selection of appropriate ventilation strategies.

Animals↗

PubMed2003

ICU cornerstone: high frequency ventilation is here to stay.

With favourable and extensive experience in the neonatal intensive care unit (ICU) and the recent positive experience in the adult ICU, high-frequency ventilation has become a valuable alternative to conventional ventilation in acute lung injury. To arrive at this point, physicians' understanding of the characteristics and kinetics of acute lung injury had to become more distinct, and it was necessary to merge accumulated knowledge from experience with high-frequency ventilation in the neonatal population and that with conventional ventilation in adults. However, this now calls for a better designed clinical trial in the adult population that combines the three most important concepts for lung protection: early intervention (before acute respiratory distress syndrome is established); optimal lung recruitment; and careful avoidance of lung over-distention over the entire period of mechanical ventilation.

Child↗

PubMed2003

Kinetics of procalcitonin, interleukin 6 and C-reactive protein after cardiopulmonary-bypass in children.

Cardiopulmonary bypass induces a generalized inflammatory response, with fever and leukocytes, which is difficult to differentiate from an infection. Recently, procalcitonin has been proposed as an early and specific marker of bacterial infection. The influence of cardiopulmonary bypass on production of procalcitonin, therefore, must be assessed before considering this molecule as a valuable marker of infection after cardiac surgery in children. With this in mind, we measured levels of procalcitonin, interleukin 6, and C-reactive protein before and 6h, 1, 3 and 5 days after cardiopulmonary bypass, in 25 children undergoing cardiac surgery. Cardiopulmonary-bypass induced a transient increase in procalcitonin, with a peak at 24 h, with a median of 1.13 microg/l, a 25th and 75th interquartile of 0.68-2.25, and a p value of less than 0.001. The value had returned to normal in the majority of the children by the third day after surgery. Peak values correlated with the duration of cardiopulmonary-bypass, with a r-value of 0.58 and a p value of 0.003; cross-clamp time, with a r-value of 0.62 and a p value of 0.001; days of mechanical ventilation, with a r-value of 0.62 and a p value of 0.001; and days of stay in intensive care, with a r-value of 0.68, and a p value of 0.0003. The value returned to normal after 3 days in 83% of the patients. Levels of interleukin 6 and C-reactive protein also increased significantly after surgery, and remained elevated for up to 5 days. Thus, in contrast to other markers, levels of procalcitonin in the serum are only slightly and transiently influenced by cardiopulmonary bypass, and may prove to be useful in the early recognition of an infection subsequent to cardiopulmonary bypass.

Adolescent↗

PubMed2003

Effects of inhaled nitric oxide and intravenous magnesium sulphate, alone and in combination, in a porcine model of hypoxic pulmonary hypertension.

BACKGROUND: In order to compare the effects of inhaled nitric oxide (NO) and magnesium (Mg) and their potential synergism on hemodynamics in pulmonary hypertension, we compared the effect of NO and Mg alone and in combination. The fact that simultaneous administration selectively increases pulmonary vascular relaxation would suggest that their association would allow for a decrease in the NO concentration required for optimal pulmonary vasodilation, thus lowering the risk of side effects. MATERIAL/METHODS: We compared the effects of 20 ppm inhaled NO, 25 mg/kg Mg, and combined therapy in a pig model of hypoxic pulmonary hypertension. Twelve animals were randomly assigned to one of 3 treatment groups: control (group 1); Mg+NO group, receiving Mg followed by NO 15 min later (group 2); NO+Mg group, receiving NO followed by Mg 15 min later (group 3). The cardiac index, pulmonary and systemic pressures, pulmonary and systemic resistance, and the pulmonary to systemic resistance ratio (PVR/SVR) were recorded at baseline, on hypoxia and 15 minutes after each drug alone and in combination. RESULTS: PVR/SVR decreased with NO alone (0.32+/-0.07 to 0.18+/-0.04; p<0.05) but not with Mg alone. When NO was added to Mg, PVR/SVR decreased significantly (0.31+/-0.06 to 0.16+/-0.02; p<0.05) but not when Mg was added to NO. CONCLUSIONS: Inhaled NO is a selective pulmonary vasodilator in a pig model of hypoxic pulmonary hypertension. The simultaneous administration of intravenous Mg does not enhance the selective pulmonary vasodilation induced by NO inhalation.

Administration, Inhalation↗

PubMed2002

Neonatal respiratory failure.

The classic entity of neonatal distress syndrome, as a lung disease expressing predominant surfactant deficiency, is currently changing to a more complex disease of the developing lung as a result of the number of extremely immature preterm infants. Prenatal factors, such as the fetal inflammatory response syndrome influence short- and long-term outcome in these premature infants presenting with respiratory distress syndrome at birth. Therefore, various previously dismissed treatment strategies, such as surfactant prophylaxis or newer anti-inflammatory approaches have to be reinvestigated in this emerging population. Despite the resurrection of a new picture of bronchopulmonary dysplasia, lung injury induced by mechanical ventilation remains a major issue in neonatal intensive care. With the advance in understanding of mechanical ventilation, it is becoming evident, that improvement in outcome can not be achieved by restoring normal lung physiology in the diseased lung using sophisticated ventilators and ventilation modes. A more disease specific ventilator strategy that will target as early as possible homogenous lung opening while at the same time avoiding overdistention of the lung, has the potential to affect outcome. The possible antiinflammatory properties of surfactant-proteins, nitric oxide and corticosteroids, despite some drawbacks, may show to have a synergistic effect. However, this needs further exploration.

Anti-Inflammatory Agents↗

PubMed2002

Successful local low-dose urokinase treatment of acquired thrombosis early after cardiothoracic surgery.

BACKGROUND AND OBJECTIVE: Recent surgery (<or=10 days) is considered an absolute contraindication for thrombolytic therapy. We report the successful use of low doses of urokinase locally infused to dissolve an intravascular thrombosis in the early postoperative period after congenital heart surgery. PATIENTS: Two children, with catheter-related intravascular thrombosis after cardiac surgery, received urokinase treatment within 24 hrs and 6 days of surgery, respectively. SETTING: Tertiary, 11-bed, pediatric intensive care unit. INTERVENTIONS: Urokinase was administered through the catheter close to the site of thrombosis with a bolus of 4400 units/kg followed by a continuous infusion of 1300 units x kg(-1) x hr(-1). MAIN RESULTS: Thrombosis resolved completely in both patients after 3 days of therapy. Signs of systemic thrombolysis were not observed. CONCLUSIONS: A short course of local low-dose urokinase is feasible and seems to be effective for thrombolysis of catheter-related thrombosis early after cardiothoracic surgery. It was not associated with bleeding in the two cases presented. Further studies are required to confirm the safety of this approach and to define optimal dosing.

Journal Article↗