Alveolar fibrinolytic capacity suppressed by injurious mechanical ventilation

OBJECTIVE

To investigate the effect of mechanical ventilation on alveolar fibrinolytic capacity.

DESIGN AND SETTING

Randomized controlled animal study in 66 Sprague-Dawley rats.

SUBJECTS AND INTERVENTIONS

Test animals received intratracheal fibrinogen and thrombin instillations; six were killed immediately (fibrin controls), and the others were allocated to three ventilation groups (ventilation period: 225 min) differing in positive inspiratory pressure and positive end-expiratory pressure, respectively: group 1, 16 cmH2O and 5 cmH2O (n=17); group 2, 26 cmH2O and 5 cmH2O (n=16); group 3, 35 cmH2O and of 5 cmH2O (n=17). Ten animals that had not been ventilated served as healthy controls.

MEASUREMENTS AND RESULTS

After animals were killed, we measured D-dimers, plasminogen activator inhibitor (PAI) 1, and tumor necrosis factor alpha in the bronchoalveolar lavage fluid and calculated lung weight and pressure/volume (P/V) plots. The median D-dimer concentration (mg/l) decreased with increasing pressure amplitude (192 in group 1, IQR 119; 66 in group 2, IQR 107; 29 in group 3, IQR 30) while median PAI-1 (U/ml) increased (undetectable in group 1; 0.55 in group 2, IQR 4.55; 3.05 in group 3, IQR 4.85). PAI-1 level was correlated with increased lung weight per bodyweight (Spearman's rank correlation 0.708). Tumor necrosis factor alpha concentration was not correlated with PAI-1 level.

CONCLUSIONS

Alveolar fibrinolytic capacity is suppressed during mechanical ventilation with high pressure amplitudes due to local production of PAI-1.

A boy with nosocomial malaria tropica contracted in a Dutch hospital

A 12-year-old Dutch boy was admitted because of severe neurotrauma after a traffic accident. On day 33 after admission, a Plasmodium falciparum infection was found in a routine blood smear. Most probably he was infected by blood of a patient next to him, a girl with severe malaria tropica. The genotype of the P. falciparum in both patients was identical.

[Unnatural and unexplained death in a paediatric intensive-care unit, 1993-2002]

OBJECTIVE

To analyse the causes of unnatural death in a general paediatric intensive-care unit.

DESIGN

Retrospective and descriptive.

METHODS

The cause of death was reviewed for all deceased children who were admitted to the paediatric intensive-care unit of the Emma Children's Hospital/Academic Medical Centre in Amsterdam, the Netherlands from 1993 through 2002. Three investigators independently categorised the cause of death as 'natural' or 'unnatural'. Unnatural death was defined as death by external cause, such as drowning, suffocation or violence, whether intentional or not. For all patients who died an unnatural death the cause of death and (if available) results of autopsy were analysed.

RESULTS

During the study period, 5523 patients were admitted to the ICU, of whom 360 (6.5%) died during the period of admission. In 45 (12.5%) of these this was an unnatural death. In 7 (16%) patients there was a suspicion of death by deliberately caused injury. In 4 of these patients forensic autopsy was performed. The results of autopsy confirmed the suspicion of child battery in 3 patients, whereas in 1 case the diagnosis was refuted.

CONCLUSION

In 16% of the children who died of unnatural causes there was a suspicion of child battery. A forensic autopsy was useful in all cases to confirm or refute the suspicion of child battery, but was not carried out in all cases.

[The transport of severely ill children in the Amsterdam region; 1995-2001]

OBJECTIVE

To inventory experiences of the transport of critically ill children in the Amsterdam region.

DESIGN

Retrospective, observational.

METHOD

Data were collected from the 1299 children who were transported to our paediatric intensive-care unit from 1 January 1995 until 31 December 2001. Severity of illness was scored and mortality risk calculated. Data on 535 children who were retrieved by our intensive-care team were compared to those from the 764 who were attended by the referring team. The impact on the outcome of distance and duration of transports from both inside and outside the Amsterdam region was analyzed.

RESULTS

Two thirds of the transports took place during the evening and night. The median age of the children was 7.5 months. Main indication for admission was respiratory or circulatory insufficiency. During the stabilizing procedure before retrieval, one or more interventions were conducted by our team in 368 (69%) of the 535 retrieved children. 940 children were transported within our region. There were no significant differences between retrieval and non-retrieval groups with respect to length of stay, length of ventilation and mortality. In patients from outside our region the mortality in the retrieval group was higher than in the non-retrieval group.

CONCLUSION

Retrieval by a specialized team did not always contribute to a favourable outcome. However, from both a logistical and a medical point of view, a retrieval system seems warranted in order to guarantee a higher level of care. There is a need for more clarity regarding the indications for retrieval by an intensive-care team.

Randomized controlled trial of aerosolized prostacyclin therapy in children with acute lung injury

OBJECTIVES

To investigate whether aerosolized prostacyclin improves oxygenation in children with acute lung injury.

DESIGN

Double-blind, randomized, and placebo-controlled trial.

SETTING

Pediatric intensive care unit at a university hospital.

PATIENTS

Fourteen children with acute lung injury defined by the criteria of an American-European Consensus Conference.

INTERVENTIONS

Aerosolized prostacyclin (epoprostenol sodium) by stepwise increments of different doses (10, 20, 30, 40, and 50 ng x kg x min) vs. aerosolized normal saline (placebo).

MEASUREMENTS AND MAIN RESULTS

Before the start of the study, and before and after each dose of prostacyclin/placebo, the following variables were measured: arterial blood gases, heart rate, mean arterial blood pressure, and ventilator settings required. Changes in oxygenation were measured by calculation of the oxygenation index (mean airway pressure x 100 x Pao2/Fio2). After treatment with aerosolized prostacyclin, there was a significant 26% (interquartile range, 3%, 35%) improvement in oxygenation index at 30 ng x kg x min compared with placebo (p =.001). The response to prostacyclin was not the same in all children. We saw an improvement of > or = 20% in eight of 14 children (i.e., responders), and the number needed to treat was 1.8 (95% confidence interval, 1.2-3.2). No adverse effects were observed.

CONCLUSIONS

Aerosolized prostacyclin improves oxygenation in children with acute lung injury. Future trials should investigate whether this treatment will positively affect outcome.

Incidence and short-term outcome of acute lung injury in mechanically ventilated children

The aim of this study was to determine the incidence and short-term outcome of mechanically ventilated children suffering from acute lung injury (ALI) on a paediatric intensive care unit (PICU). Between January 1 1998 and January 1 2000, all mechanically ventilated children were evaluated using the criteria of an American-European Consensus Conference. Of the 443 children eligible for analysis, 44 (9.9%) were diagnosed as suffering from ALI. Of these, 79.5% developed the acute respiratory distress syndrome (ARDS); 54.5% (24 of 44) fulfilled the ARDS criteria at inclusion and 25% (11 of 44) later. PICU mortality for ALI was 27.3% (12 of 44) and within the ARDS subgroup 31.4% (11 of 35). Of the 12 children who died, 11 had ARDS; the main cause of death was cerebral damage (seven of 12). Acute lung injury and acute respiratory distress syndrome are rare diseases on a paediatric intensive care unit with a high mortality. Most of the children with acute lung injury develop acute respiratory distress syndrome. In the acute respiratory distress syndrome subgroup, mortality is higher than in the acute lung injury nonacute respiratory distress syndrome subgroup. Further investigations should confirm prognostic factors (e.g. respiratory parameters) for prediction of outcome.

Immune complex associated complications in the subacute phase of meningococcal disease: incidence and literature review

AIM

To determine the incidence of immune complex associated complications (IAC) after severe meningococcal disease (SMD) in a group of Dutch children admitted to a paediatric intensive care unit (PICU).

METHODS

Retrospective chart analysis and follow up of 130 survivors of SMD admitted to PICU. Signs of IAC, inflammatory parameters, and temperature profile were reviewed.

RESULTS

Of 130 children with SMD, 20 (15.3%) showed one or more of the three manifestations of IAC: 18 (13.8%) developed arthritis (effusion, with or without erythema/arthralgia), 11 (8.4%) vasculitis, and five (3.8%) pleuritis. Eighteen of 20 (90%) patients with IAC had a secondary rise in temperature; in patients with no IAC this was 48 of 110 (43.6%). IAC was associated with leucocytosis in 82.3% versus 47.7% in patients without IAC, and with increased CRP in 86.6% versus 47.2% in patients without IAC. Leucocytes on admission were significantly lower in patients who would later develop IAC (mean 8.6 versus 13.8x10(9)/l).

CONCLUSION

IAC is a common complication of SMD, mainly occurring 4-10 days after systemic disease. IAC presents clinically as arthritis or vasculitis, mostly accompanied by secondary fever and raised inflammatory parameters.

Invasive group A streptococcal infection after tonsillectomy

Tonsillectomy is a very common procedure in childhood. Infectious complications after tonsillectomy are infrequently reported. We describe two children with severe group A beta-hemolytic streptococcal infection after tonsillectomy, and we review the literature about bacteremia and infectious complications after tonsillectomy.

[Clinical thinking and decision-making in practice. A new-born with dyspnea]

A 2-day-old girl, born at term after an uneventful pregnancy and delivery, was admitted to the paediatric intensive care unit with dyspnoea and tachypnoea. Misleading interpretations of the radiological investigations suggested a congenital diaphragmatic hernia. The patient underwent laparotomy but a diaphragmatic hernia was not found. Meanwhile the patient developed unexplained pulmonary hypertension and a progressive forward failure of the heart. The differential diagnosis did not take the pulmonary hypertension into account. Finally further investigations led to the diagnosis of a very rare congenital pulmonary vascular anomaly: an absent left pulmonary artery and systemic to pulmonary collateral arteries. The condition was considered inoperable and the patient, whose condition meanwhile had deteriorated markedly, died. This case illustrates (a) that the differential diagnosis must be based on all of the abnormal clinical findings, which should preferably be grouped together under one final diagnosis, and (b) that one must not jump to conclusions--which in this case led to unnecessary diagnostic and therapeutic interventions--, but as long as a diagnosis cannot be established, the diagnostic investigations should not be considered completed.

Dexamethasone for treatment of patients mechanically ventilated for lower respiratory tract infection caused by respiratory syncytial virus

BACKGROUND

A study was undertaken to evaluate the efficacy of dexamethasone in patients mechanically ventilated for lower respiratory infection caused by respiratory syncytial virus (RSV-LRTI).

METHODS

In a multicentre randomised controlled trial patients were randomised to receive either intravenous dexamethasone (0.15 mg/kg 6 hourly for 48 hours) or placebo. End points were the duration of mechanical ventilation, length of stay (LOS) in the pediatric intensive care unit (PICU) and in hospital, and the duration of supplemental oxygen administration.

RESULTS

Thirty seven patients received dexamethasone and 45 received placebo. There was no significant difference in any of the end points between the two groups. In a post hoc analysis patients were stratified into those with mild gas exchange anomalies (PaO(2)/FiO(2) >200 mm Hg and/or mean airway pressure </= 10 cm H(2)O, bronchiolitis group) and those with severe gas exchange anomalies (PaO(2)/FiO(2) </=200 mm Hg and mean airway pressure >10 cm H(2)O, pneumonia group). In the 39 patients with bronchiolitis the duration of mechanical ventilation was 4.3 days shorter in the dexamethasone group than in the placebo group (4.9 v 9.2 days, 95% CI -7.8 to -0.8, p=0.02) and the duration of supplemental oxygen was 3.6 days shorter (7.7 v 11.3 days, 95% CI -8.0 to -0.1, p=0.048). No differences in end points were found in the pneumonia group.

CONCLUSIONS

Dexamethasone had no beneficial effect in patients mechanically ventilated for RSV-LRTI but was found to have a beneficial effect in patients with bronchiolitis.

Membrane permeabilization in relation to inactivation kinetics of Lactobacillus species due to pulsed electric fields

Membrane permeabilization due to pulsed electric field (PEF) treatment of gram-positive Lactobacillus cells was investigated by using propidium iodide uptake and single-cell analysis with flow cytometry. Electric field strength, energy input, treatment time, and growth phase affected membrane permeabilization of Lactobacillus plantarum during PEF treatment. A correlation between PEF inactivation and membrane permeabilization of L. plantarum cells was demonstrated, whereas no relationship was observed between membrane permeabilization and heat inactivation. The same results were obtained with a Lactobacillus fermentum strain, but the latter organism was more PEF resistant and exhibited less membrane permeabilization, indicating that various bacteria have different responses to PEF treatment. While membrane permeabilization was the main factor involved in the mechanism of inactivation, the growth phase and the acidity of the environment also influenced inactivation. By using flow cytometry it was possible to sort cells in the L. plantarum population based on different cell sizes and shapes, and the results were confirmed by image analysis. An apparent effect of morphology on membrane permeabilization was observed, and larger cells were more easily permeabilized than smaller cells. In conclusion, our results indicate that the ability of PEF treatment to cause membrane permeabilization is an important factor in determining inactivation. This finding should have an effect on the final choice of the processing parameters used so that all microorganisms can be inactivated and, consequently, on the use of PEF treatment as an alternative method for preserving food products.

Biphasic positive airway pressure ventilation (PeV+) in children

Background:

Biphasic positive airway pressure (BIPAP) (also known as PeV+) is a mode of ventilation with cycling variations between two continuous positive airway pressure levels. In adults this mode of ventilation is effective and is being accepted with a decrease in need for sedatives because of the ability to breathe spontaneously during the entire breathing cycle. We studied the use of BIPAP in infants and children.

Methods:

We randomized 18 patients with respiratory failure for ventilation with either BIPAP (n = 11) or assisted spontaneous breathing (ASB) (n = 7) on Evita 4. Lorazepam and, if necessary, morphine were used as sedatives and adjusted in accordance with the Comfort scale. We compared number of randomized mode failure, duration and complications of ventilation and number and dosages of sedatives administered.

Results:

No differences in patient characteristics, ventilatory parameters, complications of ventilation or use of sedatives were noted. Ten out of eleven patients that we intended to ventilate with BIPAP were successfully ventilated with BIPAP. Four out of seven patients that we intended to ventilate with ASB could not be ventilated adequately with ASB but were successfully crossed over to BIPAP without the need for further sedatives.

Conclusions:

BIPAP is an effective, safe and easy to use mode of ventilation in infants and children.

[Clinical thinking and decision making in practice. A child with tachypnea and dyspnea]

A 6-year-old girl had been ill for a number of weeks, had fever for 5 days and complained of pain below the left costal arch and in the left shoulder, linked to the breathing. An unexplained tachypnoea was also present. The leukocyte differentiation showed 90% blasts; a bone marrow puncture then led to the diagnosis of acute non-lymphatic leukaemia, and hyperhydration and alkalinization were started. The patient died unexpectedly after a few days from massive leukostasis in pulmonary arteries. If vital functions are impaired, it should always be attempted to find an explanation, for which an underlying disease may serve as a guideline.

[Influenza A pneumonia]

The majority of influenza cases are not associated with complications. Secondary bacterial pneumonia, commonly caused by Streptococcus pneumoniae or Staphylococcus aureus, is well known to most clinicians. Primary influenza viral pneumonia, characterized by rapidly progressive hypoxia and respiratory insufficiency together with non-consolidating pulmonary infiltrates, has a high mortality rate. In 3 patients, a man aged 74 years, and two neonates aged 11 months and 4 weeks respectively, primary influenza A pneumonia was diagnosed. In the latter two patients the virus was cultivated from sputum. Despite intensive supporting and drug treatment, the first and the last patients died. In view of evolving therapeutic possibilities, notably regarding neuraminidase inhibitors, it is important that clinicians recognize this complication of influenza at an early stage.

[The necessity for centralization of pediatric intensive care]

Substantial evidence indicates that outcome of critically ill children, treated in tertiary paediatric intensive care units (PICUs) is superior to that of those treated in other settings. However, a significant number of children who require this level of care are not admitted to such a unit e.g. due to capacity constraints, reluctance of physicians of general hospitals to refer children to a tertiary centre, and transportation problems. Centralization of care, as recently proposed in the UK, is necessary in the Netherlands, as well, to improve the quality of care. This will require a controlled number of PICU beds in a restricted number of centres, adequate transport facilities and step-down or high dependency units in large general hospitals.

Flow cytometric analysis of Lactobacillus plantarum to monitor lag times, cell division and injury

Flow cytometry in combination with fluorescent molecular markers 5- (and 6-) carboxyfluorescein succinimidylester (CFSE) and propidium iodide (PI) have been applied to determine lag times, numbers of cell divisions and injury after mild heat (50 degrees C, 5 min) and nisin treatments (0.1 and 1.0 microgram ml-1) of Lactobacillus plantarum. Initial labelling with covalently bound dye CFSE (20 and 100 micrograms ml-1) allowed determination of lag times and cell proliferation for up to eight generations. Double-labelling with CFSE and PI (5 micrograms ml-1) provided additional information about damage levels and distributions within populations. Subpopulations surviving treatment could be identified easily and selectively sorted.

Staff attitudes towards continuation of life-support in newborns with major congenital anomalies

This study was conducted to gain insight into the attitudes of medical staff towards life-support of newborns with life-threatening problems, seen against the background of these children's expected morbidity and quality of life. The opinions about the mode of life-support were determined by questionnaires and the demographic characteristics of the respondents were noted. Each patient's risk of mortality was scored by means of the standardized Paediatric Risk of Mortality Score (PRISM). Attitudes towards support were unanimous for 39 of the 46 patients. For the other 7 patients at least one of the respondents preferred a different support mode than that given at the time. The attitudes were influenced by the patient's risk of mortality.

CONCLUSION

Decisions about life-support of newborns with life-threatening problems should include all the disciplines involved in patient care and should be made at an early stage.

Cerebro-costo-mandibular syndrome

We describe two boys with the cerebro-costo-mandibular syndrome (CCMS). Both patients presented with Pierre Robin anomaly and respiratory insufficiency and died 12 hours and 10 months after birth. The first boy had muscular hypotonia, severe micrognathia, glossoptosis, short palate, preauricular tag, paraumbilical fibroma, and a small and narrow thorax. His chest roentgenographs showed marked hypoplasia of the first to tenth rib, multiple posterior rib-gaps in the only four ossified ribs. Tracheomalacia and stenosis of the left ureter was observed during autopsy. No structural cerebral anomalies were observed. Respiratory distress necessitated a tracheostomy in the second boy. He had severe micrognathia with glossoptosis and a cleft soft palate were noted. His chest roentgenograph showed a bell-shaped, small thorax with multiple dorsal rib-gap defects. CCMS is a rare disorder often associated with Pierre Robin anomaly. Chest roentgenographs show the typical posterior rib-gap defects, which are quite variable. CCMS usually occurs as an isolated event in a family. Of 41 reported families four reports describe horizontal and two describe vertical transmission of CCMS. This might imply genetic heterogeneity with autosomal recessive and autosomal dominant inheritance. Inter- and intrafamilial expression is variable. Careful family studies are necessary before genetic counseling is given.

[How sick is the neonatal intensive care patient? Limited prognostic significance of the Neonatal Therapeutic Intervention Scoring System for mortality and for psychomotor development in the first year of life]

OBJECTIVE

To study the Neonatal therapeutic intervention scoring system (NTISS-score) as a prognostic indicator for mortality and psychomotor development in newborns admitted to an intensive care unit.

DESIGN

Retrospective.

SETTING

Neonatal intensive care unit, Sophia Hospital, Zwolle, the Netherlands.

METHOD

The medical files of all neonates (n = 152) admitted for intensive care in 1991 were studied. The NTISS scores at admission were compared of infants with birthweights < 1500 g and > or = 1500 g and in these groups of infants who died and infants who survived and of infants with normal and with abnormal psychomotor development in the first year of life regardless of their birthweight (data of 110 children were available from outpatient clinic control or reports from paediatricians).

RESULTS

22 infants died. There was no significant correlation between NTISS score and birthweight or gestational age (r = -0.07 and -0.03 respectively). In the group of very low birthweight infants, the NTISS score was significantly higher of the infants who died (25.9; SD: 4.3) than of those who survived (15.9; 5.0). The NTISS score did not differ between infants with normal and with abnormal psychomotor development.

CONCLUSION

The NTISS score at admission only correlates with mortality in infants with birthweights < 1500 g. There is no correlation with mortality in infants with birthweights > or = 1500 g, with gestational age or with psychomotor development in the first year of life.

Surfactant replacement therapy in neonates with respiratory failure due to bacterial sepsis

We describe four newborns (gestational ages 29-37 weeks; birthweights 1380-3040 grams) who were mechanically ventilated for respiratory insufficiency because of bacterial sepsis. A beneficial effect of bovine surfactant (Alvofact, dosages 50 or 100 mg/kg) was found, as shown by decreases in mean airway pressures and oxygen demands. No side effects were seen after instillation.

Angiotensin-converting enzyme activity is increased in lungs of rats with pulmonary hypoplasia and congenital diaphragmatic hernia

Lung hypoplasia (LH) and pulmonary hypertension are responsible for the high mortality rate in congenital diaphragmatic hernia (CDH) patients. Angiotensin-converting enzyme (ACE) plays a role in the regulation of pulmonary vascular resistance in the postnatal period and might be involved in the development of pulmonary hypertension of the newborn. A study was made of the development of ACE activity spectrophotometrically in a rat model of LH and CDH. It was previously shown that the lungs in this model are hypoplastic and the muscularization of the pulmonary vascular bed is increased. CDH was induced in fetal rats by oral administration of 115 mg/kg Nitrofen to the mother on day 10.5 of pregnancy. Fetuses were delivered by hysterotomy on days 19, 20, 21, and 22. Nitrofen-exposed rats showed significantly lower lung weights and not statistically significant lower total ACE activities than in controls. ACE activity expressed per milligram lung wet weight and per milligram protein was significantly increased compared to controls. ACE converts angiotensin I to the vasoconstrictor angiotensin II, and it inactivates the vasodilator bradykinin. Increased ACE activity may therefore contribute to pulmonary hypertension. Whether ACE and angiotensin II levels are increased in human newborns with a diaphragmatic defect and whether they contribute to the development of persistent pulmonary hypertension has not been studied up till now.

Etiological aspects of congenital diaphragmatic hernia: results of a case comparison study

We report the results of a parental questionnaire concerning possible etiological and teratological factors, such as exposure to herbicides, in the development of congenital diaphragmatic hernia (CDH). The herbicide Nitrofen interferes with lung development in rats, can induce diaphragmatic hernia and greatly resembles thyroid hormone. No association with the studied teratogens nor with maternal thyroid dysfunction was found. The questionnaire was completed by 33 parents whose baby had CDH, and by 43 couples whose baby had oesophageal atresia. The resemblance of Nitrofen to thyroid hormone, a well-known growth factor for the developing lung, is of particular interest from a pathogenetic point of view in the development of CDH.