Inter-hospital transportation of patients with severe acute respiratory failure on extracorporeal membrane oxygenation--national and international experience.

OBJECTIVE: To evaluate the experiences and results from inter-hospital transportation of patients with acute respiratory failure on extracorporeal membrane oxygenation (ECMO). DESIGN: Observational, descriptive study. SETTING: Tertiary referral center in a University Hospital. SUBJECTS AND METHODS: When standard ECMO criteria were fulfilled and the patient considered too unstable for a conventional transport, the mobile ECMO team cannulated the patient for ECMO at the referring hospital. The patients were then transported to our ECMO center by ground ambulance, helicopter or fixed-wing vehicle. Patients were also transported on ECMO from our ECMO center to other centers due to shortage of available ECMO beds. RESULTS: 29 patients (15 neonates, seven pediatric, and seven adult patients) with acute respiratory failure were transported on ECMO on a total of 30 occasions. Median time from arrival of the ECMO team at the referring hospital until the patient was on ECMO (28 patients) was 2.2 h (range 1.25-4.25 h). The median time that the transport team was out was 10 h (range 5.5-36.5 h) and the median time with the patient was 6 h (range 3-30.5 h). The distance of transport ranged from 4-1,500 km. Six transports were international. No patient complications occurred during the transports. Two technical complications related to the transport vehicle were encountered. One ambulance compressor malfunctioned. During one helicopter transport, one out of two electric supply circuits malfunctioned. The patients were not affected. Twenty-one of the 29 patients survived to discharge (72%). None of the deaths was transport related. CONCLUSIONS: Tertiary intensive care units and ECMO centers require a dedicated transport team. ECMO transports can be performed safely for all age groups for long distances, probably throughout most of Europe.

High survival in adult patients with acute respiratory distress syndrome treated by extracorporeal membrane oxygenation, minimal sedation, and pressure supported ventilation.

OBJECTIVES: To evaluate the results of treatment of severe acute respiratory distress syndrome (ARDS) with extracorporeal membrane oxygenation (ECMO), minimal sedation, and pressure supported ventilation. DESIGN AND SETTING: Observational study in a tertiary referral center, Intensive Care Unit, Astrid Lindgren Children's Hospital at Karolinska Hospital, Stockholm, Sweden. SUBJECTS AND METHODS: Seventeen adult patients with ARDS were treated with venovenous or venoarterial ECMO after failure of conventional therapy. The Murray score of pulmonary injury averaged 3.5 (3.0-4.0) and the mean PaO2/FIO2 ratio was 46 (31-65). A standard ECMO circuit with nonheparinized surfaces was used. The patients were minimally sedated and received pressure-supported ventilation. High inspiratory pressures were avoided and arterial saturation as low as 70% was accepted on venovenous bypass. RESULTS: In one patient a stable bypass could not be established. Among the remaining 16 patients 13 survived (total survival rate 76%) after 3-52 days (mean 15) on bypass. Major surgical procedures were performed in several patients. The cause of death in the three nonsurvivors was intracranial complications leading to total cerebral infarction. CONCLUSION: A high survival rate can be obtained in adult patients with severe ARDS using ECMO and pressure-supported ventilation with minimal sedation. Surgical complications are amenable to surgical treatment during ECMO. Bleeding problems can generally be controlled but require immediate and aggressive approach. It is difficult or impossible to decide when a lung disease is irreversible, and prolonged ECMO treatment may be successful even in the absence of any detectable lung function.

Successful extracorporeal membrane oxygenation in four children with malignant disease and severe Pneumocystis carinii pneumonia.

BACKGROUND: Toxic deaths due to intensified treatment are of increasing concern in view of the generally improved prognosis for children with malignancies. Pneumocystis carinii pneumonia (PCP) during immunosuppressive treatment in children with malignancies is a severe complication with a poor prognosis if mechanical ventilation is required. Extracorporeal membrane oxygenation (ECMO) is a recognized technique that provides temporary respiratory support for patients with intractable respiratory failure. PROCEDURE: We here report successful ECMO support in four children with PCP, secondary to chemotherapy-induced immunosuppression, in whom the respiratory situation deteriorated despite pharmacological treatment and mechanical ventilation. The duration of ECMO was 7-43 days. RESULTS: Three children with acute lymphoblastic leukemia recovered from their PCP to continue chemotherapy and are now in complete continuous remission. Their pulmonary function normalized completely during 6-12 months after ECMO therapy. One child with a primitive neuroectodermal tumor survived the PCP and was off ECMO for 11 days before succumbing to unrelated complications. CONCLUSIONS: We conclude that ECMO offers an important means of respiratory support in children with severe PCP that can also be adopted during treatment for malignant disease.

Improved results in patients who have congenital diaphragmatic hernia using preoperative stabilization, extracorporeal membrane oxygenation, and delayed surgery.

Congenital diaphragmatic hernia (CDH) is associated with pulmonary hypoplasia. The pulmonary vascular bed may be extremely reactive to various stimuli, and in the treatment it is important to avoid pulmonary vasospasm. The strategy in our institution since 1990 has involved a prolonged preoperative stabilization with gentle mechanical ventilation. Pressures have been kept as low as possible, and slight hypercarbia has been accepted. Peak inspiratory pressures exceeding 35 cm H2O have been avoided. Extracorporeal membrane oxygenation (ECMO) has been used according to standard inclusion criteria. Nitric oxide and high-frequency oscillation have been added to the therapeutic modalities during the study period. When the patient was considered stabilized, surgical repair was undertaken after a delay of 24 to 96 hours. In patients on ECMO who could not be decannulated, surgical repair was undertaken while on ECMO. From 1990 through 1995, 52 patients were admitted with a diagnosis of CDH. Forty-three of these were risk group patients presenting with respiratory distress within 6 hours after birth. A total of 48 patients survived (survival rate 92%), and 39 of the risk group patients (survival rate 91%). There were only four hospital deaths, all with contraindications to ECMO. It is suggested that the adopted protocol is beneficial in the treatment of CDH and that the fraction of patients who have pulmonary hypoplasia incompatible with life is smaller than previously believed.

Antilipolytic effect of insulin and insulin receptor messenger RNA expression in adipocytes of infants, children, and adults.

Human adipose tissue exhibits marked age-dependent differences in morphology and regulation of lipolysis. The mechanism behind this phenomenon is poorly characterized. The aim of the present investigation was to evaluate the antilipolytic effect of insulin and the expression of insulin receptor mRNA in human adipose tissue during development. To study the antilipolytic effect of insulin, lipolysis was induced with submaximal effective concentrations of isoprenaline or forskolin in adipocytes from five infants below 2 mo of age, five infants above 2 mo of age, six children, and five adults. Isoprenaline was equally effective in stimulating lipolysis in all age groups, whereas forskolin was significantly more effective in adipocytes isolated from adults than from infants and children. Increasing the concentration of insulin during the incubation allowed construction of dose-response curves of insulin inhibition of lipolysis. Maximal inhibition was observed with 30 microU/mL of insulin in the presence of either isoprenaline or forskolin. No differences in the maximal antilipolytic effect of insulin or in the insulin sensitivity expressed as ED50 were observed. Furthermore, the expression of insulin receptor mRNA in adipocytes did not differ from six infants, five children, and six adults as determined with a solution hybridization RNase protection assay. Thus, age-dependent variations in the regulation of lipolysis do not appear to be accompanied by variations in insulin action and insulin receptor gene expression in isolated adipocytes.

Carmeda surface heparinization in neonatal ECMO systems: long-term experiments in a sheep model.

The thromboresistance in three Carmeda (Stockholm, Sweden) heparin-coated neonatal ECMO systems with a runtime of 45, 56 and 96 hours, respectively, and three noncoated systems with a runtime of 12, 42 and 66 hours, respectively, were compared using a sheep model. The flow rate was 200 ml/min and the activated clotting time (ACT) was kept at approximately 120 seconds. At the end of the experiment, the heparin-coated systems only contained minimal clotting while the controls showed major clotting in the entire system. Fibrin monomers were not detected until after 24 hours in the heparin-coated group, but demonstrated within 60 minutes in the noncoated group. It is concluded that the Carmeda heparin coating has a thromboresistant effect, and may be used to reduce the need for systemic heparinization in ECMO treatment of neonates.

Pediatric ECMO for pulmonary support: experience from 12 cases.

Extracorporeal membrane oxygenation (ECMO), which can be described as treatment with a modified heart-lung machine over a prolonged period of time, is used to support patients with life-threatening but potentially reversible lung failure. ECMO by itself does not cure the patient but gives the lungs a chance to rest while awaiting spontaneous or therapeutic healing. The method is well documented in the neonatal age group. In the non-neonatal age group, however, experience is less extensive. This report of the initial result from our hospital with 12 non-neonatal pediatric cases shows high survival and low morbidity. Nine of the 12 patients were able to be weaned from ECMO (75% survival) and 8 of these 9 patients were long-term survivors. Medium time on the ventilator after discontinuation of ECMO was 4 days. At follow-up, all long-term survivors had no signs of neurological or pulmonary sequelae. These encouraging results point to the fact that ECMO should be considered more often in cases of life-threatening but potentially reversible pulmonary failure.

Respiratory insufficiency as a cause of neonatal death (with aspects on the potential need for ECMO treatment).

In order to identify children with fatal outcome in a neonatal intensive care unit in which only outborns are admitted, a retrospective study over a 10-year period was undertaken. The study was limited to respiratory disorders. The aim of the study was to identify lethal risk factors and thereby the need for improving therapeutic tools. Diagnoses, perinatal history, ventilator settings, blood gases, medical treatment, X-ray findings, head ultrasounds, echocardiograms, laboratory tests, surgical procedures and autopsy findings were evaluated. Severe respiratory insufficiency requiring mechanical ventilation was found in 777 patients and of these babies, 207 (27%) died while still on the ventilator. Fifty-eight patients were excluded for various reasons and thus 149 patients were included in the study. It is concluded that the mortality rate from respiratory insufficiency in the material studied was consistently high over the 10-year period. New therapeutic modalities, one of which is ECMO, are offered nowadays in clinical practice and may improve mortality and morbidity rates.

Diaphragmatic hernia in infancy and childhood--20 years experience.

Congenital diaphragmatic hernia through the foramen of Bochdalek usually presents with severe respiratory symptoms soon after birth. Despite successful repair of the defect the mortality rate still remains high. This may be due to co-existing pulmonary hypoplasia with pulmonary hypertension and concomitant right-to-left shunting. In order to find factors that predispose for good or bad outcome as well as to compare different modalities of treatment being used at our hospital, this twenty-year retrospective study was undertaken. It is confirmed that the extent of pulmonary hypoplasia at birth rather than the promptness of surgical repair and the skill of intensive care appears to be the major mortality factor. Initial experiences from extracorporeal membrane oxygenation (ECMO) are promising.

Surface-heparinized neonatal ECMO circuit--an experimental animal study.

The present experiment examined the capacity of the Carmeda Bioactive Surface to prevent clot formation in an ECMO circuit designed for neonatal use. The Terumo Capiox oxygenator was used in the seven experiments. Mongrel dogs were perfused with veno-arterial bypass at a low flow rate of 200 ml/min. Without any blood heparinization, the circuit was totally occluded within a few hours. With a very low heparin infusion (10 IUxkg -1xh -1) extracorporeal blood flow could be maintained despite some clots forming in the oxygenator. With a small bolus injection of heparin (20 IU/kg) and a low continuous heparin infusion (20 IUxkg -1xh -1) the ECMO circuit showed negligible clotting. With better haemodynamic design of the device in combination with a thrombo-resistant surface, it may be possible to decrease the need for blood heparinization in the neonatal ECMO circuit.

Patient complications during extracorporeal membrane oxygenation (ECMO).

Extracorporeal membrane oxygenation (ECMO) has rapidly become the treatment of choice for critically ill newborns with reversible pulmonary disease not responding to conventional treatment. Since 1987 ECMO has been available at our hospital and up to December 1989 11 patients were treated. Several patient complications were seen. The aim of this study was to register the incidence and treatment of these complications and to compare our results with international ECMO experience. It is concluded that many of the complications seen during ECMO can be successfully managed.

Extracorporeal membrane oxygenation in a European center--clinical experience.

Extracorporeal membrane oxygenation (ECMO) has rapidly become the treatment of choice for critically ill newborn infants with reversible pulmonary disease refractory to conventional treatment. Since 1987 ECMO has been available at our hospital and up to December 1989 11 patients have been treated. Eight patients could be weaned from ECMO. The aim of this study was to describe the procedure and its implications in the neonatal and pediatric age groups and to present our experience. It is concluded that even though ECMO in the short term is a costly and personnel-consuming procedure it is well documented, safe and life-saving.

Damage to the right coronary artery as a cause of death after aortic valve surgery.

During a 6-year period (1983-1988), 1137 patients underwent surgery which included replacement of the aortic valve. There were 73 deaths within 30 days of surgery. A retrospective analysis showed that in four cases the cause of death probably was related to intraoperative damage to the right coronary artery, which in three cases was accidentally obstructed by a suture and in the fourth case was found at autopsy to be occluded by an organized thrombus. None of the four patients died intraoperatively. Death occurred 2 hours to 20 days postoperatively from arrhythmia and/or pump failure caused by myocardial infarction.

In-vitro evaluation of neonatal ECMO cannulae with regard to flow characteristics.

One of the crucial points in a neonatal ECMO circuit is to obtain adequate venous drainage from the cannula in the right jugular vein, as the vessel diameter limits the size of cannula that can be used. For this reason the design of the cannula is of utmost importance. The aim of this paper was to compare different commercially available ECMO cannulae, and to try to find the cannula which had the best flow characteristics. Venous cannulae were evaluated with regard to maximum drainage capacity at different hydrostatic levels. For arterial use, pressure drop over the cannulae at different flow rates was measured. Of the cannulae studied, those from Biomedicus and Elecath had the best flow characteristics for both venous and arterial use.

Regulation of lipolysis during the neonatal period. Importance of thyrotropin.

We investigated the lipolytic effect of several hormones on isolated human adipocytes obtained at different donor ages. In neonates, noradrenaline and adrenaline had an insignificant lipolytic effect (70% over basal). In this age group only thyrotropin (TSH) had a significant effect in physiological concentrations, and the maximal lipolytic effect (700% over basal) was the same as that of isoprenaline. The lipolytic effect of TSH was the same in premature 4-10-wk-old infants with a gestational age of 27-33 wk as in neonates, but fat cells from infants 4-10 wk old, born at term, showed a significantly lower effect. In children and adults, the lipolytic effect of TSH gradually decreased further and was present only in unphysiological concentrations. The catecholamine-induced lipolysis was pronounced and was similar in children and adults (350% over basal). TSH is the dominating lipolytic hormone in vitro during the neonatal period. Thus, the peak elevation of circulating TSH, which is seen immediately after birth, may be essential to lipolysis during this part of life.