Effect of early intervention of high-frequency oscillatory ventilation on the outcome in pediatric acute respiratory distress syndrome.

BACKGROUND: Acute respiratory failure in both pediatric and adult patient populations has been extensively studied with recent emphasis on ventilation strategies that can effect mortality outcome. This research in adults has focused on definitive trials of lung protective strategies that have been proposed following preliminary reports of their potential benefits. High frequency oscillatory ventilation has also been described as a lung protective strategy. For many institutions HFOV is today considered a routine therapy as a "rescue" method in acute pediatric respiratory failure. Because HFOV is considered to be a "rescue" therapy, intervention with HFOV is usually in the later stages of acute respiratory failure and consideration of the time to intervention has not been previously examined. OBJECTIVE: To evaluate the effect of time to intervention with high-frequency oscillatory ventilation (HFOV) on the survival of children with severe acute hypoxemic respiratory failure who were managed with lung protective strategies on conventional mechanical ventilation (CMV). METHODS: Twenty-six consecutive patients older 1 month of age with severe hypoxemic respiratory failure and ARDS who at some point in their management were treated with HFOV were evaluated. The mean age was 3.7 years and included three patients treated in the Pediatric Intensive Care Unit (17, 19 and 24 years). Mean weight was 13.8 kg and there were 17 males and 9 females. Nine patients met Extracorporeal Membrane Oxygenation (ECMO) criteria, although only two patients were cannulated. Upon admission to the PICU, patients were initially managed with lung protective strategies using Pressure Controlled Ventilation (PCV) or Pressure Regulated Volume Control (PRVC) modes with limited peak inspiratory pressure, high positive end-expiratory pressure, and permissive hypercapnia. If a Pa-CO2 reached > 75 torr (10.0 kPa) and/or pH < 7.20, tracheal gas insufflation (TGI) was instituted. If FiO2 remained above 0.6 and mean airway pressure (Paw) exceeded 15 cmH2O in order to maintain arterial saturation above 89% or if hypercapnia and/or acidosis on CMV with TGI persisted, the patients were switched to HFOV. An "Optimal Volume Strategy" with HFOV was utilized to recruit alveoli and optimize lung volume. Patients were returned to CMV when their mean airway pressure were between 15 and 20 cmH2O, FiO2 < 0.6, had no evidence of air-leak and/or improved chest X-rays, and did not desaturated during airway suctioning. Patients were offered ECMO if the hypoxemia persisted on HFOV and there were no contraindications to its use. The patients were stratified for analysis by the time to intervention with HFOV. Early intervention was defined as within the first 24 hours of mechanical ventilation (17 patients) and late intervention defined patients beyond 24 hours (9 patients). Demographic data (gender, age, weight, admission PRISM score), time of each mode of ventilation, oxygenation indices and outcomes were recorded for both groups of patients. MAIN RESULTS: The severity of respiratory failure at the time of HFOV intervention was comparable in both early and late groups (PaCO2/FiO2 83 vs. 79 torr, oxygenation index 27 vs. 33, AaDO2 421 torr (56 kPa) vs. 413 torr (55 kPa)). There were no differences in mean age, weight, admission PRISM score length of HFOV, length of CMV after HFOV (CMV post-HFOV) and the total duration of mechanical ventilation between the groups. We found a statistically significant difference in mortality with 58.8% of the early intervention patients surviving while only 12.5% of the late intervention patients survived. The overall survival rate was 42% (11/26 patients). CONCLUSION: Early use of HFOV within the first 24 hours of acute hypoxic respiratory failure in pediatric patients is associated with better survival. Use of this therapy should be considered early in the course of treatment of any pediatric patient meeting this definition. (Tab. 2, Fig. 1, Ref. 28.)

Partial liquid ventilation in the therapy of pediatric acute respiratory distress syndrome.

BACKGROUND: Acute respiratory failure represents life-threatening disease with persistently marked mortality and late morbidity in pre-term newborns (RDS--respiratory distress syndrome), children as well as, adults (ARDS--acute respiratory distress syndrome). We are probably in the period when better understanding of pulmonary pathophysiology enables the development of new technologies that can help in decreasing the morbidity and mortality of patients with respiratory failure. One of these unconventional methods is partial liquid ventilation (PLV). MAIN PURPOSE: The main aim of the study was to verify the possibility of treating potentially reversible respiratory failure in patients where extracorporeal life support (ECLS) was contraindicated and extracorporeal membrane oxygenation (ECMO) could not be used, or the patient had not met the criteria for ECMO. METHODS: PLV was used in 6 children totally, in 7 applications with severe hypoxemic respiratory failure. Preoxygenated perfluorocarbon Rimar 101 (Miteni, Milan, Italy) warmed to 37 degrees C was applied intratracheally in the doses which corresponds with the functional residual capacity of lungs, the dose of perfluorocarbon was repeated every hour. Following parameters were recorded before, during and after PLV: pH, blood gases, ventilator setting, alveoloarterial difference for oxygen, dynamic compliance, and indices--oxygenation index and hypoxemia score (PaO2/FiO2). The values obtained 1 hour before PLV were compared with the values during PLV; the data before PLV and in the 3rd hour of PLV were evaluated statistically. RESULTS: Statistically significant increase of pH (7.22 vs 7.34, p < 0.05) and PaO2/FiO2 (72 vs 100 Torr, p < 0.01) and decrease of FiO2 (82% vs 64%, p < 0.05) and oxygenation index (23 vs 17, p < 0.05) occurred during 3 hours of PLV. CONCLUSION: Partial liquid ventilation is an effective method for controlling ARDS in certain groups of patients with severe lung disease. (Tab. 4, Ref. 15.)

[Treatment of congenital diaphragmatic hernia using ECMO]. / Lécba vrozené bránicní kýly s vyuzitím ECMO.

The authors present a case dealing with the treatment of a congenital diaphragmatic hernia. The procedure comprises surgery, extracorporeal membrane oxygenation--ECMO, classical and non-conventional pulmonary ventilation and pharmacological treatment. By using these methods it is possible to treat successfully a certain group of neonates with a congenital diaphragmatic hernia.

[Liquid ventilation. 2]. / Kapalinová ventilace--2. cást.

The authors made two series of experiments in rabbits, using liquid ventilation. The first group was ventilated manually using RM 101 solution with an equilibration period of 30 and 60 sec., Tv = 10 ml/kg after previous administration of 30 ml/kg RM 101 at the beginning. The second group was ventilated using a specially developed liquid ventilator--part of the animals was ventilated with an equilibration interval of 30-90 sec., Tv = 10 ml/kg with administration of an initial dose od 30 ml/kg of RM 101 solution, a part of the animals in a continual manner, i.e. without an equilibration period and without administration of the initial dose of the solution. From the results it is apparent that the optimal way as regards blood gases and minimal manner of liquid ventilation. When this method was used during the 180 minutes of liquid ventilation paO2, paCO2 and pH were within the normal range. The other methods of liquid ventilation led rapidly to hypercapnia and a drop of pH as well as to serious changes in the circulation (hypertension, bradyarrhythmia).

[Liquid ventilation--1]. / Kapalinová ventilace--1. cást.

The authors investigated in detail the sorption and desorption of oxygen and carbon dioxide in a solution of perfluorocarbons (solution RM 101, Miteni, Italy). From the results of the investigation ensues that maximal oxygen saturation of 77.3 vol.% can be achieved at 8 degrees C. With rising temperature the oxygen concentration in the solution declines (67.6 vol.% at 37 degrees). The saturation of the RM 101 solution corresponds to a linear equation of seventh order (fig. 2). Desorption of the RM 101 solution fully saturated with carbon dioxide, is on the other hand, most rapid at 37 degrees C (after the 13th minute the RM 101 solution contains less than 2% carbon dioxide as compared with 25 vol.% at 8 degrees C during the same period. In general the kinetics of desorption of carbon dioxide in solution correspond to a linear equation of fifth order (fig. 4). From the practical aspect it is not expedient to saturate the RM 101 solution with oxygen longer than 15-20 minutes. The mentioned kinetic parameters are important for the construction of a special liquid membrane or bubble oxygenator. In particular the latter is useful as with its use the authors achieved a 1.9 x higher oxygen concentration in the RM 101 solution than declared by the manufacturer.

[Extracorporeal membrane oxygenation. Initial experience at an ECMO center. 1]. / Extracorporeal membrane oxygenation (ECMO). První zkusenosti ECMO centra (1. cást).

The authors describe their initial experience, organization, and problems associated with the development of an EMCO centre. Its main activities are those of a neonatal ECMO centre (to a smaller extent paediatric ECMO and ECCO2R-LF PPV of adults) during the first 4 months of its existence. During the period the ECMO centre was contacted in 10 instances. The referring department indicated the ECMO centre correctly in six instances. However, at least in two instances too late and the patients died (during priming of the ECMO circuit or transport could not be implemented because of the critical condition). In two instances, however, the ECMO staff failed as it was unable to ensure a minimum of seven days of safe operation of ECMO and therefore ECMO was not provided. Based on this experience the authors present an organizational model of the ECMO unit which is formed ad hoc when needed and comprises specialists of various professions from the sphere of emergency medicine. The main purpose of the present paper is to inform referring departments on the indications, selection criteria, contraindications of ECMO in neonates and children and to ensure thus not only smooth communication between the ECMO centre and the referring department but in the first place early referral to the ECMO centre at a time when transport is not yet a problem.

[Non-immunologic fetal hydrops]. / Hydrops fétu neimunologické povahy (HFNP).

The authors demonstrate two cases of non-immunological foetal hydrops. In the first case the initial cause of foetal hydrops was hypoalbuminaemia (hypoproteinaemia), in the second case intrauterine cardiac failure resulting from supraventricular tachycardia of unknown aetiology. The authors explain the pathogenesis of the condition, its early diagnosis and therapy. They draw attention to possible intoxication of the neonate by digoxin administered to the mother during pregnancy.

[Pneumoperitoneum in a premature, non-ventilated neonate with respiratory distress syndrome leading to respiratory failure. What is the etiology?]. / Pneumoperitoneum u nezralého, neventilovaného novorozence s RDS vedouci k respiracnímu selhání. Jaký muze mít puvod?

The authors describe the finding of extensive tensive pneumoperitoneum which developed during distension therapy (CNP) in an immature neonate. The absence of another extraalveolar cumulation of air made the authors use PO2 analysis in the peritoneal air by means of a transcutaneous electrode. Because the PO2 rose after connection of the electrode to the catheter draining the abdominal cavity, the authors assumed a respiratory aetiology of the pneumoperitoneum and did not consider laparatomy. They assume that the above test may be valuable in the differential diagnosis between respiratory and gastrointestinal pneumoperitoneum in those instances where it is not possible to assess the aetiology of pneumoperitoneum unequivocally.

[High frequency "bubble" oscillation ventilation in the neonatal period]. / "Bublinková" vysokofrekvencni oscilacni ventilace v novorozeneckém obdobi.

The authors tested their own high frequency, oscillation, "bubble" ventilator on a model of neonatal lungs in vitro and in vivo. They used the effect of oscillations which develop when through fluid (in vivo water) a mixture of air is bubbled and which can be, if the expiration tube is sufficiently rigid, transmitted back into the lungs. If the CPAP circuit is suitably arranged, it can ensure an adequate exchange of blood gases. The authors found marked changes in the amplitude of pressure oscillations as well as of the frequency in relation to the shape of the ending beneath the fluid surface (greatest when a funnel with a 30 mm diameter and 90 degree angle in relation to a normal line projected on the water surface is used). They found that the compliance (C) has no substantial effect on the amplitude nor on the frequency of oscillations. The mentioned bubble system approached as to its efficiency the commercial oscillation ventilator Stephen 3000 SFH and was used in the therapy of respiratory failure in three neonates with body weights of 1250-2700 g. The authors conclude that high frequency oscillation "bubble" ventilation is a cheap, safe and highly effective therapy which can be used in any department providing care of neonates even during transport.

[Acoustic frequency analysis of auscultation findings in neonates]. / Akustická frekvencní analýza auskultacních nálezu u novorozencu.

The authors analyzed 280 auscultation findings of 35 neonates with birth weights of 1800-4500 g and 65 pathological neonates with birth weights of 1150-3600 g. For recording of the auscultation findings an electronic phonendoscope EST 40 (Bosch) was used and the finding was recorded on a microtape recorder (Olympus). The frequency analysis was made on a Sonagraf analyzer (Kay Elemetric), using a 45 Hz filter a time range of 2.4 sec. From the results of the work ensues that in physiological neonates two basis types of sonagrams can be detected: 1. the record presenting itself as a continuous zone of noise with maximal cumulation of acoustic energy up to 500 Hz where the ratio of acoustic energy is equal in both stages of the respiratory cycle. The clinical correlate is "alveolar respiration". 2. a record with a discontinuous zone of noise with a more expressive ratio of acoustic energy up to 2500 Hz during inspiration. The clinical correlate is "sharper bronchoalveolar respiration". In the group of pathological neonates with different pneumopathies further sonagraphic phenomena were detected: a) "rales" as discontinuous acoustic phenomena persisting for 7-35 msec with a frequency range up to 3000 Hz, without a harmonious structure, present during inspiration as well as expiration, b) "transmitted phenomena"--discontinuous acoustic phenomena persisting for 75-150 msec with a frequency range up to 6000 Hz, without a harmonious structure, c) "wheezing"--continuous acoustic phenomena with a clearly marked harmonious acoustic structure lasting 540 +/- 240 msec with a frequency of the basic sound of 500 +/- 240 msec.(ABSTRACT TRUNCATED AT 250 WORDS)

[Massive systemic and intracranial air embolisms in a premature child with severe RDS syndrome treated with high-frequency oscillation ventilation]. / Masivní systémová a intrakraniální vzduchová embolie u nezralého dítete s tezkým RDS syndromem, léceným vysokofrekvencní oscilacní ventilací (HFOV).

The authors present a case of massive systemic air embolism with an unusual X-ray finding which developed during high-frequency oscillation ventilation (HFOV), paradoxically when minimal inflation pressures were used. The air was detected by X-ray not only in the systemic circulation but also intracranially (in the area of the cisterna magna, cerebral sinuses and intraventricularly). They draw attention to the fact that even the application of non-conventional ventilation methods does not rule out the development of this serious complication and they recommend, when this complications is suspected, to examine by X-ray also the cranium. This is the first report in the literature where intracranial embolization developed during HFOV.

[Sonographic analysis of postextubation stridor in neonates and children with low birth weight after long-term artificial ventilation]. / Sonagrafická analýza postextubacního stridoru novorozencu a detí nízkých porodních hmotností po dlouhodobé artificiální ventilaci.

In a group of 23 neonates with mean birth weights of 1470 g (range 1200-3980 g) who had orotracheal intubation for an average period of 12.6 days (range 5-96 days) sonagraphic frequency analysis of 86 stridors 1-3 hours after intubation was performed. According to the results of the frequency analysis more than 97.6% of the stridors are supraglottic (84 of 86 analyzed stridors). The laryngeal and tracheal type of stridor was recorded only in two children. The finding is surprising and does not confirm the widely accepted view that neonates after extubation are threatened with oedema of the larynx or stricture at this or a distal level. As elective postextubation laryngoscopy is controversial, acoustic frequency analysis of stridor after extubation is a suitable alternate method in investigations of the clinical condition of the infant and serves the clinician as an indication on the level of stenosis of the airways.