Benefits of the low pressure multichannel endotracheal ventilation

Mechanical ventilation using a modified endotracheal tube, allowing bypass and washout of the endotracheal dead space (McETV), was compared with conventional controlled mechanical ventilation (CMV) in healthy and in surfactant-depleted rabbits. In healthy animals, shifting from CMV to McETV led to an increase in PaO2 (89 +/- 16 versus 104 +/- 13 mm Hg; p < 0.05) and a decrease in PaCO2 (41.5 +/- 3 versus 30 +/- 3 mm Hg; p < 0.05). As a result of reducing the peak inspiratory pressure (PIP) from 21 +/- 2 to 12 +/- 2 cm H2O (p < 0.05), it was possible in McETV mode to maintain comparable ventilation to that achieved by CMV. In surfactant-depleted animals, compared with CMV, McETV produced a rise in PaO2 without change in thoracic volume (from 100 +/- 40 to 150 +/- 60 mm Hg, p < 0.05) and a fall in PaCO2 (from 46 +/- 5 to 37 +/- 4 mm Hg, p < 0.05). After 4 h of ventilation, the surfactant-depleted animals from the CMV group developed thoracic overdistension quicker (at hour 1, p < 0.05) and, consequently, more animals died from pneumothorax compared with the McETV group (five versus two). We concluded that McETV ensured adequate gas exchanges with lower insufflation pressures and could diminish positive pressure ventilation-induced injury.

Thrombosis of the arterial cannula during extracorporeal membrane oxygenation in a full-term newborn infant

The authors report a rare case of cannula thrombosis during extracorporeal membrane oxygenation (ECMO). A full-term newborn infant was successively placed on single-cannula veno-venous extracorporeal lung support and then on veno-arterial ECMO, because of persistent pulmonary hypertension. At 140 hours of ECMO, the infant displayed general cyanosis except in the right arm. Since asymmetric hypoxemia during ECMO may be related either to cannula malposition or to a tip thrombosis, a chest x-ray after contrast injection into the arterial line of the circuit was performed. It showed an opacification of the whole cannula but for the last distal centimeter, and of the vascular bed extending from the right subclavian artery. Cannula thrombosis was suspected and confirmed by removal of the arterial cannula. Demonstration of cannula thrombosis by opacification of the arterial line of the circuit indicates catheter removal.

[Accidents in children. Retrospective epidemiological study of 1671 cases collected at the Hotel-Dieu of Beirut]

Injuries are the first cause of death in children after the neonatal age; their prevention is still critical in Lebanon. At Hotel-Dieu de France Hospital, 1671 children aged less than 18 years have had their files reviewed in the emergency department. Minor traumas represent less than half the cases. Though most of the injuries were light, in 5% of cases primary care was necessary, and 11% were admitted (10% in the Pediatric Intensive Care Unit); 0.5% of the children died upon arrival. Moreover, 15% of our Pediatric Intensive Care Unit population are admitted for accidents. Boys are more frequently affected (69%); toddlers, small children and adolescents are risky populations. After minor traumas, the most frequent accidents are: falls (21.3%), traffic road accidents (8.9%), poisoning (5.7%) and burns (5%). Firearms injuries seem rare (2.8%) but are, in this study, the first cause of mortality. Foreign body inhalation are very rare (< 1%) but are a significant source of morbidity. This analysis is compared to published data, and allows accurate and general recommendations for injuries prevention in children.

[Bronchopulmonary dysplasia: outcome and treatment of severe forms]

BACKGROUND

The outcome of severe forms of bronchopulmonary dysplasia (BPD) leading to a prolonged dependence on mechanical ventilation (MV) and/or oxygen therapy (O2) is not evaluated, and factors of guidance to treatment are not established.

POPULATION AND METHODS

The medical records of 49 infants, born between 1982 and 1990, with BPD who required MV and or O2 after 12 months of life were retrospectively reviewed. Three groups of infants were defined: group I: 26 infants on MV since birth; group II: seven infants weaned from MV after the first month of life then put back on MV belatedly; group III: 16 infants on spontaneous ventilation (SV) under O2.

RESULTS

At 12 months of age, the 49 infants showed sleep hypoxemia, failure to thrive and 28% of them pulmonary hypertension. Comparison between MV and O2 infants indicated that subjects on MV had pulmonary dynamic compliance (Cl dyn) lower than 50% (p = 0.01), ventilatory work including respiratory frequency in rest > 40 cycles/min; 70% of them had asynchronous thoracic and abdominal muscles during sleep (p < 0.01 for all comparisons). Seventy percent of patients had bronchospasms (p = 0.02). The 49 infants had a favourable outcome, allowing weaning from MV or O2 between the ages of 2 and 4 years.

CONCLUSIONS

These findings suggest that major respiratory failure in prematurely born infants can be overcome with prolonged respiratory and nutritional supports during the post-natal period of lung development; Cl dyn < 50% is a cursor for prolonged MV and weaning from MV should be excluded as long as increased ventilatory work persists.

Randomly amplified polymorphic DNA analysis provides rapid differentiation of methicillin-resistant coagulase-negative staphylococcus bacteremia isolates in pediatric hospital

Coagulase-negative staphylococci (CoNS) are now recognized as the most common cause of nosocomial bacteremia in pediatric patients. Randomly amplified polymorphic DNA analysis was used to study the relationships among 12 isolates of CoNS obtained from eight patients with catheter-related bacteremia in two distinct wards of our hospital and 6 epidemiologically unrelated strains. With this method, we were able to discriminate isolates that otherwise were indistinguishable by conventional criteria such as biochemical typing and antibiotic susceptibility patterns. Our results indicate that there were episodes of cross-infections among four patients in one ward but independent infectious episodes among four patients in the other ward. Randomly amplified polymorphic DNA analysis is a rapid method which seems particularly well suited to the epidemiological study of CoNS isolates.

Is there a role for inhaled nitric oxide in pediatric ARDS?

Despite advances in ventilator management and use of extracorporeal lung support, mortality related to ARDS in pediatric patients has not been reduced over the past 20 years. Progressive respiratory failure, due to evolution of the primary illness or to complications of ventilator therapy, significantly contributes to poor outcome. ARDS is characterized by severe ventilation-perfusion mismatch and by pulmonary hypertension. Because of their side effects which affect systemic hemodynamic status or worsen intrapulmonary shunting, intravenous vasodilator trials have been of limited interest. Nitric oxide (NO) has been recognized as a gas with vasodilator properties. In neonates studies have shown that inhaled NO may have an important role in the therapy of persistent pulmonary hypertension. Inhaled NO in adults with severe ARDS has been shown to reduce pulmonary hypertension without producing systemic vasodilation. This reduction of pulmonary vascular resistances may reduce pulmonary edema formation, decrease vasoconstrictor response to cardiotonic agents, and improve biventricular function. In addition, arterial oxygenation seems to be increased by improved matching of ventilation with perfusion. Improvement of oxygenation with inhaled NO suggests that use of lower tidal volumes and FIO2 may be more successful. Until now, there are no published studies regarding NO administration in ARDS affecting nonneonatal pediatric patients. However, the results obtained in adults and newborns suggest that inhaled NO may be a useful adjuvant therapy of ARDS in children, possibly in association with other therapies. Even in adults it remains unclear whether therapy with inhaled NO can reduce morbidity and mortality. Prospectives and randomized studies are essential to assess the real utility of inhaled NO in ARDS.(ABSTRACT TRUNCATED AT 250 WORDS)

Placebo-controlled trial of midazolam sedation in mechanically ventilated newborn babies

Although midazolam is used for sedation of mechanically ventilated newborn babies, this treatment has not been evaluated in a randomised trial. We have done a prospective placebo-controlled study of the effects of midazolam on haemodynamic variables and sedation as judged by a five-item behaviour score. 46 newborn babies on mechanical ventilation for respiratory distress syndrome were randomly assigned to receive midazolam (n = 24) or placebo (n = 22) as a continuous infusion. Doses of midazolam were calculated to obtain plasma concentrations between 200 and 1000 ng/mL within 24 h of starting treatment and to maintain these values throughout the study. Haemodynamic and ventilatory variables were noted every hour, as were complications and possible side-effects of treatment. Mean (SD) duration of inclusion was 78.7 (30.9) h. 1 patient in the treatment group and 7 in the placebo group were withdrawn because of inadequate sedation (p < 0.05). Midazolam gave a significantly better sedative effect than placebo, as estimated by the behaviour score (p < 0.05). Heart rate and blood pressure were reduced by treatment but remained within the normal range for gestational age and there was no effect on ventilatory indices. The incidence of complications was similar in the two groups. No midazolam-related side-effects were noted. Continuous infusion of midazolam at doses adapted to gestational age induces effective sedation in newborn babies on mechanical ventilation, with positive effects on haemodynamic variables. The course of the respiratory distress syndrome was not influenced by this treatment. Midazolam was given over only a few days and the limited effects on heart rate and blood pressure that we report should not encourage long-term administration.

Doppler echocardiographic assessment of pulmonary circulation in severe respiratory failure of the neonate: an aid for extracorporeal lung support indications

Extracorporeal lung support (ECLS) for newborns with acute respiratory failure has achieved increased popularity over the last decade. However, precise criteria for its implementation remain controversial. The aim of this study was to assess the value of Doppler echocardiography (DE) in 31 neonates with PaO2 of < or = 50 mmHg, FIO2 of 1, and optimal ventilation. Treatment included mechanical ventilation, paralysis, volume loading, vasopressors, and tolazoline. Markers indicative of ECLS (failure of maximal medical therapy, assessed by AaDO2 of more than 610 mm Hg beyond 8 hours and/or an oxygenation index (OI = mean airway pressure x FIO2%/postductal PaO2) of more than 40 beyond 4 to 6 hours) were present in 23 (group 1) and absent in eight (group 2). Shunt direction and systolic pulmonary arterial pressure (sPAP) calculated from tricuspid insufficiency velocity were assessed using DE. At the time of admission, sPAP was significantly higher in group 1 (62.1 v 43.7 mm Hg). On day 1, group 1 differed from group 2 in maximum sPAP value (73.2 v 44.4 mm Hg), PaCO2 (56.1 v 40 mm Hg), right-to-left shunting (85% v 25% of the patients), and pulmonary-to-systemic-pressure systolic ratio (sPAP:sSAP) (1.29 v 0.75). Patients with an sPAP:sSAP ratio of more than 1 and patients with high sPAP associated with high PaCO2 on day 1, all later (average, 10 hours later) fulfilled ECLS criteria; this suggests that DE assessment of pulmonary circulation may yield early and predictive markers of impending ECLS indication. Further confirmation of these results would help avoid unnecessary delays in ECLS implementation in newborns with severe respiratory failure.

[Severe poisoning risk linked to intravenous administration of quinine]

BACKGROUND

High concentrations of quinine, the drug of choice for severe malaria, are toxic to the cardiovascular system, producing hypotension and abnormal myocardial conduction.

CASE REPORTS

Five children, aged 14 months to 13 years, were admitted because of fever that appeared a few days after their return from an area in which malaria was endemic. Examination of a thick blood film showed Plasmodium falciparum. They were given quinine intravenously. Four children developed a seizure that recurred in three of them; the fifth child suffered from headache, buzzing in the ears and vision anomalies. Four children rapidly developed hypotension followed by cardiac arrest. All children had abnormal ECG. Retrospective study of the instructions given for quinine administration showed that they were inexplicit and were responsible for incorrect dilution of the drug. Four of the five children recovered completely. The fifth child developed ventricular tachycardia followed by bradycardia that did not respond to resuscitation.

CONCLUSION

Major errors can be made in prescribing intravenous quinine. This type of treatment must be carefully monitored and is only indicated in severe forms of malaria, which our patients were not suffering from.

[Total abnormal pulmonary venous return. Preoperative stabilization by extracorporeal veno-venous circulation]

BACKGROUND

Total anomalous pulmonary venous return (TAPVR) is a rare congenital cardiac disease. When this includes pulmonary artery hypertension, the infant is severely ill. Survival beyond infancy is rare without surgical correction.

CASE REPORT

A girl in whom hydramnios and a short femur were discovered by ultrasonography at the 25th week of gestation was admitted to the intensive care unit a few hours after birth because of respiratory distress. Blood PaO2 was 37 mmHg, PaCO2, 36 mmHg, and pH 7.25. She had tachycardia (190/min) and circulatory insufficiency. Echocardiography showed right ventricular overload, a right-to-left shunt through a patent ductus arteriosus and foramen ovale and tricuspid insufficiency. This refractory hypoxemia was not corrected by conventional respiratory support, high-frequency oscillation plus dobutamine and dopamine followed by noradrenaline infusion. Because of further deterioration, the baby was given extracorporeal lung support; this rapidly improved the respiratory and hemodynamic conditions. Persistent pulmonary artery hypertension led to a second investigation that showed TAPVR She underwent emergency surgery.

CONCLUSION

Extracorporeal lung support can stabilize a precarious state in a case of severe congenital cardiac disease, so allowing surgical treatment under satisfactory conditions.

[Anuria after abdominal surgery in 2 newborn infants. Beneficial effect of noradrenaline]

BACKGROUND

Abdominal surgery in neonates may be complicated by acute renal failure that is sometimes due to increased intra-abdominal pressure. Correction of the decreased renal perfusion may be difficult.

CASE REPORTS

Case no 1. A girl weighing 3,000 g was operated on at 3 hours of life for congenital omphalocele. Closing the defect induced increased intra-abdominal pressure and decreased systemic pressure. Despite dopamine, dobutamine, followed by furosemide, anuria persisted without manifestations of heart failure. Noradrenaline (0.1 to 0.7 micrograms/kg/min intravenously) given 24 hours after surgery resulted in normalization of systemic pressure and diuresis. Case no 2. A boy was born at gestational week 30, weighing 1,450 g. At 8 days of age, he was suffering from shock that was attributed to perforation of the bowel due to necrotizing enterocolitis. Surgery was complicated by acute circulatory and renal failure that did not respond to dopamine, dobutamine or furosemide. Infusion of noradrenaline, (0.2 to 0.6 micrograms/kg/min intravenously) induced diuresis within 3 hours.

CONCLUSIONS

Noradrenaline can be useful in patients with postoperative increased intra-abdominal pressure. It should only be given after correction of hypovolemia, control of myocardial function, and when dopamine remains ineffective.

[Analysis of emergency recruitment in a pediatric hospital. Effect on the organization of available care]

BACKGROUND

The increasing demand on the emergency wards of pediatric hospitals raise the question of whether the services delivered are adequate for the explicit and implicit needs of outpatients.

POPULATION AND METHODS

The files of all the 334 children consulting at the medical emergency ward of Robert-Debré hospital in Paris between April 19 and April 26, 1989 were analyzed. Socio-demographic data, reasons for visit and final diagnosis were collected. Each outpatient was assigned to one of 3 categories: 1) severe emergency; 2) simple emergency; 3) consultation. Further data on the events leading to the visit were obtained by a second survey covering 213 children seen between May 11 and May 14, 1991 from 8 hrs to 20 hrs.

RESULTS

The mean age of the 334 children in the first survey was 3.2 years. Half of the mothers were unemployed. Half of the families was of foreign extraction. 3.4% of the children had no social insurance. Ten percent of the patients were frequent users of the emergency ward. Infectious diseases were the most prevalent reason for visit. Severe emergencies were 28%, simple emergencies 44% and consultations 28%. Among the 213 children of the second survey, half of the families had seen (43%) or attempted to see (7%) a physician outside the hospital before coming to the emergency ward.

CONCLUSION

The needs of the children could best be met by performing a true medico-social examination at the medical emergency ward, enhancing access for children and revitalizing a partnership with the community to provide continuous care for those children in need of it.

[Characteristics of the fibrinolytic system in the newborn]

Recent development of microassays and determination of age-specific normal ranges have shed new light on the components and functioning of the neonatal fibrinolytic system. Plasminogen and tissue plasminogen activator levels are low in neonates, who generate plasmin more slowly and in smaller amounts than adults. Quantitative and qualitative changes occur as the fibrinolytic system matures. This is also true of the coagulation system responsible for the production of thrombin, which is the target for plasmin. These data are essential to assess the risk of thrombosis in neonates and, if appropriate, to guide management decisions including selection of a thrombolytic agent, of the optimal dosage, and of the best laboratory tests for monitoring purposes. Ongoing studies are investigating the mechanisms involved in neonatal lysis of thrombin clots occurring naturally or as the result of thrombolytic therapy.

[Thrombosis of the renal veins in the newborn: treatment and long term prognosis]

Thirty-nine neonates with renal vein thrombosis diagnosed in our hospital department between 1973 and 1991 were studied retrospectively. Twenty-five patients were and 14 were not treated with urokinase (UK). Among the five deaths (13%), four occurred at the acute stage from non-renal complications and one occurred at the age of three months from end-stage renal failure. Eight patients (21%) have moderate renal failure after a mean follow-up of 7.4 years; a single patient (2%) developed end-stage renal failure after 7.9 years and 25 patients (64%) have a normal glomerular filtration rate after a mean follow-up of 4.5 years. Rates of death and chronic renal failure were 8% and 32%, respectively, in the group given UK and 21% and 7%, respectively, in the group not given UK. Among 54 involved kidneys, only 10 (19%) recovered normal function and morphological features. Functional impairment was seen in 11 of 37 (30%) kidneys treated by UK and 10 of 17 (59%) kidneys not treated by UK. Although these data suggest that UK may be effective in promoting recanalization of renal veins obstructed by thrombosis, confirmatory evidence could be obtained only by performing a prospective therapeutic trial.

[Treatment of renal vein thromboses in the newborn]

Surgical thrombectomy is not a rational approach to neonatal renal vein thrombosis since the occlusion mainly involves intrarenal branches rather than the main renal vein, which is even patent in some instances. Conservative management combines supportive therapy for renal failure and systemic hypertension, if needed, and either heparin or thrombolytic agents. Streptokinase has proven difficult to handle in neonates and should not be used. Urokinase has been used in 18 patients but results are difficult to interpret because these cases occurred over an 18-year period. Plasminogen tissue activator, the latest thrombolytic agent developed, has been used in few pediatric patients. An international task force is currently studying whether or not a randomized study is warranted to provide data for standardizing thrombolytic therapy in pediatric renal vein thrombosis.

[Continuous arteriovenous hemofiltration. Management in case of neonatal leucinosis]

BACKGROUND

Neonates with classic maple syrup urine disease (MSUD) undergo rapid neurological deterioration by the end of the first week of life. Exchange transfusion and peritoneal dialysis are the usual emergency treatment. Continuous arteriovenous hemofiltration (CAVHF) appears to be safe and more rapidly effective.

CASE REPORT

Martin was born at the 37th week from a normal pregnancy. Abnormal movements of legs and lethargy appeared on the 7th day of life. Progressive brain dysfunction with coma led to intubation on the 13th day. A diagnosis of MSUD was immediately made and CAVHF was initiated and continued for 19 hours. The plasma leucine, valine and isoleucine levels fell from 2,248 to 275, 640 to 91 and 298 to 13 mumol/l, respectively. Neurologic improvement was dramatic, except for moderate hypertonia which lasted for the 2 following days.

CONCLUSION

CAVHF is an appropriate treatment for very young patients with inborn errors of metabolism. It appears safer and more rapidly effective for eliminating branched-chain amino acids than other techniques, such as peritoneal dialysis with or without exchange transfusions. It also permits more rapid introduction of the specific diet.