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Biomedical subjects

Frans B Plötz

Publications and source records attributed to Frans B Plötz.

At least 19 recordsLinked to original sources
PubMed2006

Circumstances surrounding dying in the paediatric intensive care unit.

BACKGROUND: Death is inevitable in the paediatric intensive care unit (PICU). We aimed to describe the circumstances surrounding dying in a PICU. METHOD: The chart records of all patients less than 18 years of age who died at the PICU between January first 2000 and July first 2005 were retrospectively analyzed. Information regarding sex, age, length of stay, admission, diagnosis, and the way a patient died was registered. Post mortem information regarding natural versus unnatural death, autopsy and donation was obtained. Non-survivors were allocated in five groups: do-not-resuscitate (DNR), withholding and/or withdrawal of therapy (W/W), failed cardiopulmonary resuscitation (failed CPR), brain death (BD), and terminal organ failure (TOF). RESULTS: During the study period 87 (4.4%) of the 1995 admitted patients died. Non-survivors were more often admitted during the day (54%) and the week (68%). W/W was found in 27.6%, TOF in 26.4%, BD in 23.0%, failed CPR in 18.4%, and DNR in 4.6%. Forty-three percent died in the first two days, of which BD (40.5%) and failed CPR (37.8%) were most common. Seventy-five children (86%) died due to a natural cause. Autopsy permission was obtained in 19 of 54 patients (35%). The autopsies confirmed the clinical diagnosis in 11 patients, revealed new information in 5 patients, and in 3 patients the autopsy did not provide additional information. Nine patients were medically suitable for organ donation and 24 patients for tissue donation, whereas consent was only obtained in 2 cases in both groups. CONCLUSION: We observed that 43% of the patients died within the first two days of admission due to BD and failed CPR, whereas after 4 days most patients died after W/W. Autopsy remains an useful tool to confirm clinical diagnoses or to provide new information. Only a small percentage of the deceased children is suitable for organ donation.

Autopsy↗
PubMed2006

Imposed work of breathing during high-frequency oscillatory ventilation: a bench study.

INTRODUCTION: The ventilator and the endotracheal tube impose additional workload in mechanically ventilated patients breathing spontaneously. The total work of breathing (WOB) includes elastic and resistive work. In a bench test we assessed the imposed WOB using 3100 A/3100 B SensorMedics high-frequency oscillatory ventilators. METHODS: A computer-controlled piston-driven test lung was used to simulate a spontaneously breathing patient. The test lung was connected to a high-frequency oscillatory ventilation (HFOV) ventilator by an endotracheal tube. The inspiratory and expiratory airway flows and pressures at various places were sampled. The spontaneous breath rate and volume, tube size and ventilator settings were simulated as representative of the newborn to adult range. The fresh gas flow rate was set at a low and a high level. The imposed WOB was calculated using the Campbell diagram. RESULTS: In the simulations for newborns (assumed body weight 3.5 kg) and infants (assumed body weight 10 kg) the imposed WOB (mean +/- standard deviation) was 0.22 +/- 0.07 and 0.87 +/- 0.25 J/l, respectively. Comparison of the imposed WOB in low and high fresh gas flow rate measurements yielded values of 1.63 +/- 0.32 and 0.96 +/- 0.24 J/l (P = 0.01) in small children (assumed body weight 25 kg), of 1.81 +/- 0.30 and 1.10 +/- 0.27 J/l (P < 0.001) in large children (assumed body weight 40 kg), and of 1.95 +/- 0.31 and 1.12 +/- 0.34 J/l (P < 0.01) in adults (assumed body weight 70 kg). High peak inspiratory flow and low fresh gas flow rate significantly increased the imposed WOB. Mean airway pressure in the breathing circuit decreased dramatically during spontaneous breathing, most markedly at the low fresh gas flow rate. This led to ventilator shut-off when the inspiratory flow exceeded the fresh gas flow. CONCLUSION: Spontaneous breathing during HFOV resulted in considerable imposed WOB in pediatric and adult simulations, explaining the discomfort seen in those patients breathing spontaneously during HFOV. The level of imposed WOB was lower in the newborn and infant simulations, explaining why these patients tolerate spontaneous breathing during HFOV well. A high fresh gas flow rate reduced the imposed WOB. These findings suggest the need for a demand flow system based on patient need allowing spontaneous breathing during HFOV.

Computer Simulation↗
PubMed2006

Unloading work of breathing during high-frequency oscillatory ventilation: a bench study.

INTRODUCTION: With the 3100B high-frequency oscillatory ventilator (SensorMedics, Yorba Linda, CA, USA), patients' spontaneous breathing efforts result in a high level of imposed work of breathing (WOB). Therefore, spontaneous breathing often has to be suppressed during high-frequency oscillatory ventilation (HFOV). A demand-flow system was designed to reduce imposed WOB. METHODS: An external gas flow controller (demand-flow system) accommodates the ventilator fresh gas flow during spontaneous breathing simulation. A control algorithm detects breathing effort and regulates the demand-flow valve. The effectiveness of this system has been evaluated in a bench test. The Campbell diagram and pressure time product (PTP) are used to quantify the imposed workload. RESULTS: Using the demand-flow system, imposed WOB is considerably reduced. The demand-flow system reduces inspiratory imposed WOB by 30% to 56% and inspiratory imposed PTP by 38% to 59% compared to continuous fresh gas flow. Expiratory imposed WOB was decreased as well by 12% to 49%. In simulations of shallow to normal breathing for an adult, imposed WOB is 0.5 J l-1 at maximum. Fluctuations in mean airway pressure on account of spontaneous breathing are markedly reduced. CONCLUSION: The use of the demand-flow system during HFOV results in a reduction of both imposed WOB and fluctuation in mean airway pressure. The level of imposed WOB was reduced to the physiological range of WOB. Potentially, this makes maintenance of spontaneous breathing during HFOV possible and easier in a clinical setting. Early initiation of HFOV seems more possible with this system and the possibility of weaning of patients directly on a high-frequency oscillatory ventilator is not excluded either.

High-Frequency Ventilation↗
PubMed2005

Bench-to-bedside review: Paediatric viral lower respiratory tract disease necessitating mechanical ventilation--should we use exogenous surfactant?

Treatment of infants with viral lower respiratory tract disease (LRTD) necessitating mechanical ventilation is mainly symptomatic. The therapeutic use of surfactant seems rational because significantly lower levels of surfactant phospholipids and proteins, and impaired capacity to reduce surface tension were observed among infants and young children with viral LRTD. This article reviews the role of pulmonary surfactant in the pathogenesis of paediatric viral LRTD. Three randomized trials demonstrated improved oxygenation and reduced duration of mechanical ventilation and paediatric intensive care unit stay in young children with viral LRTD after administration of exogenous surfactant. This suggest that exogenous surfactant is the first beneficial treatment for ventilated infants with viral LRTD. Additionally, in vitro and animal studies demonstrated that surfactant associated proteins SP-A and SP-D bind to respiratory viruses, play a role in eliminating these viruses and induce an inflammatory response. Although these immunomodulating effects are promising, the available data are inconclusive and the findings are unconfirmed in humans. In summary, exogenous surfactant in ventilated infants with viral LRTD could be a useful therapeutic approach. Its beneficial role in improving oxygenation has already been established in clinical trials, whereas the immunomodulating effects are promising but remain to be elucidated.

Animals↗
PubMed2005

Therapeutic total plasma exchange in a child with neuroblastoma-related anti-Hu syndrome.

A 5-year-old boy underwent total plasma exchange to remove anti-neuronal anti-Hu autoantibodies as a complication of neuroblastoma, leading to autonomic bowel dysfunction. Total plasma exchange (TPE) resulted eventually in a reduction of autoantibody levels, but, more importantly, led to improvement of bowel function. TPE proved to be a safe and effective treatment option in neuroblastoma-related anti-Hu syndrome in a child.

Autoantibodies↗
PubMed2005

Effect of acute renal failure on outcome in children with severe septic shock.

Acute renal failure (ARF) requiring renal replacement therapy (RRT) has been associated with an excess risk of mortality in adult patients with septic shock, but it is unknown whether this is also applicable to pediatric patients. We therefore conducted a retrospective pilot study. All children presenting with septic shock between 1st January 1998 and 1st April 2004 were analyzed. Patients with fluid refractory-dopamine resistant shock, necessitating the use of noradrenaline, were included. ARF was defined as the deterioration of renal function to the extent that renal replacement therapy was required (ARF group). This ARF group was compared with patients without ARF (non-ARF group). Out of the 22 children with severe septic shock, seven developed ARF. PIM2 and PRISM scores upon admission were comparable between both groups. Mortality rates were significantly higher in patients with ARF (57.1% vs 6.7%; p=0.02). Pediatric patients with severe septic shock developing ARF have excess mortality compared to pediatric patients who do not develop ARF, although on diagnosis, severity of underlying disease and calculated risk of mortality were comparable. A multicenter trial is necessary to confirm these findings and to determine the contribution of ARF to pediatric sepsis mortality.

Acute Kidney Injury↗
PubMed2005

High-frequency oscillatory ventilation in children: a single-center experience of 53 cases.

INTRODUCTION: The present article reports our experience with high-frequency oscillatory ventilation (HFOV) in pediatric patients who deteriorated on conventional mechanical ventilation. METHODS: The chart records of 53 consecutively HFOV-treated patients from 1 January 1998 to 1 April 2004 were retrospectively analyzed. The parameters of demographic data, cause of respiratory insufficiency, Pediatric Index of Mortality score, oxygenation index and PaCO2 were recorded and calculated at various time points before and after the start of HFOV, along with patient outcome and cause of death. RESULTS: The overall survival rate was 64%. We observed remarkable differences in outcome depending on the cause of respiratory insufficiency; survival was 56% in patients with diffuse alveolar disease (DAD) and was 88% in patients with small airway disease (SAD). The oxygenation index was significantly higher before and during HFOV in DAD patients than in SAD patients. The PaCO2 prior to HFOV was higher in SAD patients compared with DAD patients and returned to normal values after the initiation of HFOV. CONCLUSION: HFOV rescue therapy was associated with a high survival percentage in a selected group of children. Patients with DAD primarily had oxygenation failure. Future studies are necessary to evaluate whether the outcome in this group of patients may be improved if HFOV is applied earlier in the course of disease. Patients with SAD primarily had severe hypercapnia and HFOV therapy was very effective in achieving adequate ventilation.

Child↗
PubMed2005

Mechanical ventilation and acute renal failure.

OBJECTIVE: To review the current literature on possible mechanisms by which mechanical ventilation may initiate or aggravate acute renal failure. DATA SOURCE: A Medline database and references from identified articles were used to perform a literature search relating to mechanical ventilation and acute renal failure. DATA SYNTHESIS: Acute renal failure may be initiated or aggravated by mechanical ventilation through three different mechanisms. First, strategies such as permissive hypercapnia or permissive hypoxemia may compromise renal blood flow. Second, through effects on cardiac output, mechanical ventilation affects systemic and renal hemodynamics. Third, mechanical ventilation may cause biotrauma-a pulmonary inflammatory reaction that may generate systemic release of inflammatory mediators. The harmful effects of mechanical ventilation may become more significant when a comorbidity is present. In these situations, it is more difficult to maintain normal gas exchange, and moderate arterial hypoxemia and hypercapnia are often accepted. Renal blood flow is compromised due to a decreased cardiac output as a consequence of high intrathoracic pressures. Furthermore, the effects of biotrauma are not limited to the lungs but may lead to a systemic inflammatory reaction. CONCLUSIONS: The development of acute renal failure during mechanical ventilation likely represents a multifactorial process that may become more important in the presence of comorbidities. Development of optimal interventional strategies requires an understanding of physiologic principles and greater insight into the precise molecular and cellular mechanisms that may also play a role.

Acute Kidney Injury↗
PubMed2004

Ventilator-induced lung injury and multiple system organ failure: a critical review of facts and hypotheses.

OBJECTIVE: To review how biotrauma leads to the development of multiple system organ failure (MSOF). DESIGN AND SETTING: Published articles on experimental and clinical studies and review articles in the English language were collected and analyzed. RESULTS: The concept that ventilation strategies using "large" tidal volumes and zero PEEP of injured lungs can enhance injury by the release of inflammatory mediators into the lungs and circulation, a mechanism that has been called biotrauma, is supported by evidence from experimental models ranging from mechanically stressed cell systems, to isolated lungs, intact animals, and humans. Biotrauma may lead to MSOF via spillover of lung-borne inflammatory mediators into the systemic circulation. However, spillover of other agents such as bacteria and soluble proapoptotic factors may also contribute to the onset of MSOF. Other less well studied mechanisms such as peripheral immunosuppression and translocation of bacteria and/or products from the gut may play an important role. Finally, genetic variability is a crucial factor. CONCLUSIONS: The development of MSOF is a multifactorial process. Our proposed mechanisms linking mechanical ventilation and MSOF suggest several novel therapeutic approaches. However, it will first be necessary to study the mechanisms described above to delineate more precisely the contribution of each proposed factor, their interrelationships, and their time course. We suggest that scientific advances in immunology may offer novel approaches for prevention of MSOF secondary to ventilator-induced lung injury.

Animals↗