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Biomedical subjects

D J Macrae

Publications and source records attributed to D J Macrae.

At least 19 recordsLinked to original sources
PubMed1997

Extracorporeal support for intractable cardiorespiratory failure due to meningococcal disease.

BACKGROUND: Meningococcal disease is still associated with considerable mortality, despite the use of early antibiotics and management in specialised intensive care units, due principally to early refractory myocardial depression and hypotension as well as severe acute respiratory distress syndrome. Extracorporeal membrane oxygenation (ECMO) is a complex technology that uses a modified "heart-lung" machine to provide temporary cardiac and respiratory support. We reviewed the UK and Australian experience of the use of ECMO in patients with refractory cardiorespiratory failure due to meningococcal disease. METHODS: The records from all 12 known patients supported with ECMO for meningococcal disease in the UK and Australia since 1989 were reviewed. FINDINGS: 12 patients (aged 4 months to 18 years, median 26 months) with meningococcal disease received ECMO over 8 years. In seven patients, ECMO was required early for cardiac support for intractable shock within 36 h of admission to intensive care. In the other five patients, ECMO was indicated for respiratory failure due to severe adult respiratory distress syndrome, which tended to occur later in the disease. The paediatric risk of mortality score ranged from 13 to 40 (median 29, median predicted risk of mortality 72%). Six of the 12 patients required cardiopulmonary resuscitation before ECMO and the other six were deteriorating despite maximal conventional therapy. Overall, eight of the 12 patients survived, with six leading functionally normal lives at a median of 1 year (range 4 months to 4 years) of follow-up. INTERPRETATION: ECMO might be considered to support patients with intractable cardiorespiratory failure due to meningococcal disease who are not responding to conventional treatment.

Adolescent↗
PubMed1997

Carotid artery pseudoaneurysm as a complication of ECMO.

Any pulsatile neck mass after extracorporeal membrane oxygenation (ECMO) must be viewed as a pseudoaneurysm of the carotid artery until proven otherwise. Prompt diagnosis is necessary utilizing ultrasound. Angiography may not be necessary. Carotid artery pseudoaneurysm requires urgent surgical intervention to prevent catastrophic hemorrhage. The utilization of cardiopulmonary bypass may facilitate safe repair.

Aneurysm, False↗
PubMed1997

Early response to inhaled nitric oxide and its relationship to outcome in children with severe hypoxemic respiratory failure.

OBJECTIVE: To examine whether the early response to inhaled nitric oxide (iNO) is a measure of reversibility of lung injury and patient outcome in children with acute hypoxemic respiratory failure (AHRF). DESIGN: Retrospective review study. SETTING: Pediatric ICUs. PATIENTS: Thirty infants and children, aged 1 month to 13 years (median, 7 months) with severe AHRF (mean alveolar arterial oxygen gradient of 568+/-9.3 mm Hg, PaO2/fraction of inspired oxygen of 56+/-2.3, oxygenation index [OI] of 41+/-3.8, and acute lung injury score of 2.8+/-0.1). Eighteen patients had ARDS. INTERVENTIONS: The magnitude of the early response to iNO was quantified as the percentage change in OI occurring within 60 min of initiating 20 ppm iNO therapy. This response was compared to patient outcome data. MEASUREMENTS AND RESULTS: There was a significant association between early response to iNO and patient outcome (Kendall tau B r=0.43, p < 0.02). All six patients who showed < 15% improvement in OI died; 4 of the 11 patients (36%) who had a 15 to 30% improvement in OI survived, while 8 of 13 (61%) who had a > 30% improvement in OI survived. Overall, 12 patients (40%) survived, 9 with ongoing conventional treatment including iNO, and 3 with extracorporeal support. CONCLUSIONS: In AHRF in children, greater early response to iNO appears to be associated with improved outcome. This may reflect reversibility of pulmonary pathophysiologic condition and serve as a bedside marker of disease stage.

Acute Disease↗
PubMed1996

Pharmacological control of pulmonary blood flow with inhaled nitric oxide after the fenestrated Fontan operation.

BACKGROUND: A transient increase in pulmonary vascular resistance can result in hemodynamic compromise after a Fontan operation. An interatrial fenestration is designed to maintain cardiac output in these circumstances but may result in severe hypoxemia and a vicious circle due to hypoxemia induced pulmonary vasoconstriction. Our aim was to determine whether inhaled nitric oxide (iNO), a selective pulmonary vasodilator, could be used to reduce pulmonary vascular resistance in desaturated patients (SaO2 < or = 85%) after a fenestrated Fontan operation. METHODS AND RESULTS: Responses to iNO (20 ppm for 15 min) were assessed in 10 consecutive children with SaO2 < or = 85% and compared with 5 with SaO2 > 85% after a fenestrated Fontan operation. Exposure to iNO resulted in a significant increase in SaO2 (from 64 +/- 5% to 82 +/- 2%, P < .01) and reduction in transpulmonary gradient (TPG) (from 12.2 +/- 1 [SEM] to 9.6 +/- 1.1, P < .01) in patients with baseline SaO2 < or = 85%. Baseline saturation was a predictor of response to iNO, with a greater response in those with lower saturations (r = -.86, P < .01). In contrast, no significant effects were noted in PaO2 or TPG (from 122 +/- 46 mm Hg and 8 +/- 1.8 to 123 +/- 43 mm Hg and 7 +/- 1.2, respectively) in patients with baseline SaO2 > 85%. CONCLUSIONS: iNO improved both oxygenation and TPG in desaturated patients after the fenestrated Fontan operation, possibly by counteracting hypoxemia-induced pulmonary vasoconstriction. A trial of iNO should be considered in clinically unstable desaturated patients after the fenestrated Fontan operation.

Administration, Inhalation↗
PubMed1996

Nitric oxide might reduce the need for extracorporeal support in children with critical postoperative pulmonary hypertension.

BACKGROUND: Postoperative pulmonary hypertension is a life-threatening, yet reversible complication of congenital heart operations. Although inhaled nitric oxide (iNO), a selective pulmonary vasodilator, has been shown extensively to improve short-term oxygenation and hemodynamic indices in these patients, its influence on patient outcome has not been evaluated. The purpose of this study was to assess retrospectively whether patients who fulfilled our criteria for extracorporeal life support (ECLS) for critical postoperative pulmonary hypertension still required ECLS after the administration of iNO therapy. METHODS: Since January 1992, 10 patients (age 3 days to 10 months) fulfilled the criteria at our institution for ECLS for postoperative pulmonary hypertension. Of these, 5 could not be separated from cardiopulmonary bypass because of pulmonary hypertension, and 5 had critical pulmonary hypertension (pulmonary arterial pressure approaching systemic arterial pressure) causing severe cardiopulmonary compromise. RESULTS: Six of the 10 ECLS candidates had a sustained response to iNO and survived to discharge from the hospital, without the need for rescue ECLS. Three patients still required ECLS after 30 minutes, 4 hours, and 8 hours of beginning iNO because of failing cardiac output, and 2 survived. The remaining patient died after 5 days of iNO therapy, but was no longer a candidate for ECLS because of sepsis and multiorgan system failure. CONCLUSIONS: Children with critical pulmonary hypertension unresponsive to maximal conventional treatment may be managed successfully with iNO without the need for rescue ECLS. A trial of iNO should therefore be given before the use of ECLS in these patients.

Administration, Inhalation↗
PubMed1996

Extracorporeal membrane oxygenation as a bridge to definitive tracheal surgery in children.

Extracorporeal membrane oxygenation was used as a bridge for three infants with complicated long segment congenital tracheal stenosis to tracheal homograft transplantation with cadaveric tracheal homograft and for one child, with an extensive traumatic tracheal laceration caused by aspiration of a sharp foreign body, to definitive tracheal repair. In all four cases mechanical ventilation was impossible and death almost certain without extracorporeal membrane oxygenation.

Cadaver↗
PubMed1996

Four patterns of response to inhaled nitric oxide for persistent pulmonary hypertension of the newborn.

OBJECTIVE: To determine the clinical role of inhaled nitric oxide (iNO) in the treatment of persistent pulmonary hypertension of the newborn (PPHN). STUDY DESIGN: Prospective open observational clinical study. SETTING: A regional cardiac and pediatric intensive care unit. METHODS: Twenty-five consecutive near-term neonates (> 35 weeks gestation) with severe PPHN (oxygenation index [OI] > 25) were given a trial of iNO of 20 ppm for 20 minutes. Neonates who showed a greater than 20% improvement in PaO2 as well as a decrease in the OI to below 40 were defined as responders and continued on this therapy. RESULTS: Four patterns of response emerged to the iNO therapy: Pattern 1 neonates (n = 2) did not respond to the initial trial of iNO-one survived. Pattern 2 neonates (n = 9) responded to the initial trial of iNO, but failed to sustain this response over 36 hours, as defined by a rise in the OI to > 40. Six survived, five with extracorporeal membrane oxygenation. Pattern 3 neonates (n = 11) responded to the initial trial of iNO, sustained this response, and were successfully weaned from iNO within 5 days--all survived to discharge. Pattern 4 neonates (n = 3) responded to the initial trial of iNO, but developed a sustained dependence on iNO for 3 to 6 weeks. All three died and lung histology revealed severe pulmonary hypoplasia and dysplasia. These neonates (pattern 4) not only required iNO for a longer period of time than did the sustained responders (pattern 3), but they required significantly higher doses of iNO during their first 5 days of iNO therapy. CONCLUSIONS: Early responses to iNO may not be sustained. Neonates with pulmonary hypoplasia and dysplasia may have a decreased sensitivity and differing time course of response to iNO when compared with patients who have PPHN in fully developed lungs.

Administration, Inhalation↗
PubMed1995

Nitric oxide is superior to prostacyclin for pulmonary hypertension after cardiac operations.

BACKGROUND: Severe pulmonary hypertension is still a cause of morbidity and mortality in children after cardiac operations. The objective of this study was to compare the vasodilator properties of inhaled nitric oxide, a novel pulmonary vasodilator, and intravenous prostacyclin in the treatment of severe postoperative pulmonary hypertension. METHODS: Thirteen children (aged 3 days to 12 months) with severe pulmonary hypertension after cardiac operations were given inhaled nitric oxide (20 ppm x 10 minutes) and intravenous prostacyclin (20 ng.kg-1.min-1 x 10 minutes) in a prospective, randomized cross-over study. RESULTS: Both nitric oxide and prostacyclin resulted in a reduction in pulmonary arterial pressure, although the mean pulmonary arterial pressure was significantly lower during nitric oxide therapy (28.5 +/- 2.9 mm Hg) than during prostacyclin therapy (35.4 +/- 2.1 mm Hg; p < 0.05). The mean pulmonary to systemic arterial pressure ratio was also significantly lower during nitric oxide than prostacylin administration (0.46 +/- 0.04 versus 0.68 +/- 0.05; p < 0.01), due mainly to only prostacyclin lowering systemic blood pressure. CONCLUSIONS: Inhaled nitric oxide was a more effective and selective pulmonary vasodilator than prostacyclin and should be considered as the preferred treatment for severe postoperative pulmonary hypertension.

Cross-Over Studies↗
PubMed1994

Guidelines for the safe administration of inhaled nitric oxide.

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator, potentially useful in the treatment of pulmonary hypertension and ventilation-perfusion mismatch. High doses of inhaled NO and its oxidative product nitrogen dioxide (NO2) may cause acute lung injury. Using a standard infant ventilator, ventilator circuit and test lung, an administration and monitoring strategy has been defined for inhaled NO and these observations validated in eight ventilated infants. In 90% oxygen, doses of inhaled NO > or = 80 parts per million may result in toxic NO2 concentrations.

Administration, Inhalation↗
PubMed1994

Very-low-dose inhaled nitric oxide: a selective pulmonary vasodilator after operations for congenital heart disease.

Inhaled low-dose nitric oxide (2, 10, 20 ppm), together with high inspired oxygen concentration (0.80), was administered after corrective operations 13 times to 10 infants (median age 6 months) who were at risk of postoperative pulmonary hypertension because of their congenital heart disease and left-to-right shunt. Inhaled nitric oxide, even in a very low dose (2 ppm), caused selective pulmonary vasodilatation. The pulmonary/systemic artery pressure ratio was a predictor of the response to nitric oxide, with a greater response being seen in those with a high ratio (> or = 0.50). In children with a high pulmonary/systemic pressure ratio, the mean pulmonary vascular resistance index fell by 37% to 42%, accompanied by only a 10% fall in the systemic vascular resistance index but a 14% to 16% rise in mean cardiac index. No toxicity was seen in any subject. This exciting new therapy may prove to be an important adjunct in the management of postoperative pulmonary hypertension in the child with congenital heart disease.

Administration, Inhalation↗