Efficacy of prone ventilation in adult patients with acute respiratory failure: a meta-analysis

PURPOSE

The use of prone ventilation in acute respiratory failure has been investigated by several randomized controlled trials in the recent past. To date, there has been no systematic review or meta-analysis of these trials.

MATERIAL AND METHODS

Systematic literature search was performed between 1966 and July 2006 to identify randomized trials evaluating prone ventilation. Outcome measures included mortality, changes in oxygenation, incidence of pneumonia, duration of mechanical ventilation, intensive care unit (ICU) and hospital stay, cost-effectiveness, and adverse effects including pressure sores, endotracheal tube, or intravascular catheter complications.

RESULTS

Prone ventilation was not associated with reduction in mortality, but improvement in oxygenation was statistically significant (mean difference, 21.2 mm Hg; P < .001). There was no significant difference in incidence of pneumonia, ICU stay, and endotracheal tube complications. There was a trend toward an increased incidence of pressure sores in prone ventilated patients (odds ratio = 1.95; 95% confidence interval, 0.09-4.15; P = .08). The data on other outcomes were not suitable for meta-analysis.

CONCLUSIONS

The use of prone ventilation is associated with improved oxygenation. It is not associated with a reduction in mortality, pneumonia, or ICU stay and may be associated with an increased incidence of pressure sores.

Referral pattern of neonates with severe respiratory failure for extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) remains the mainstay of management in neonates with severe but potentially reversible respiratory failure. In the UK, ECMO is available only as a supraregional service at four centres.

OBJECTIVE

To explore regional variations in ECMO referrals and neonatal deaths due to severe respiratory failure in England, Wales and Northern Ireland.

METHODS

In this retrospective study, data regarding ECMO referrals due to neonatal respiratory failure from January to December 2002 were obtained from the four UK ECMO centres and then subdivided according to the Government Office Regions. Anonymised data regarding neonatal deaths was obtained from Confidential Enquiry into Maternal and Child Health. Neonatal deaths were classified into four groups (group 1: deaths potentially avoidable by ECMO; group 2: deaths where it was unclear whether ECMO would have been of benefit; group 3: neonates not eligible for ECMO; and group 4: data inadequate to classify deaths).

RESULTS

There was significant regional variation in the rates of both ECMO referral (0.10 to 0.46 per 1000 live births; (p<0.001)) and neonatal deaths (groups 1 and 2) (0.09 to 0.32 per 1000 live births; (p<0.001)). Regions with high referral rates for ECMO tended towards having higher group 1 plus group 2 neonatal death rates (correlation coefficient = 0.75).

CONCLUSION

It is possible that there are significant regional variations in the uptake of ECMO and in neonatal mortality due to severe respiratory failure. A confidential prospective study may further clarify these observations and identify the factors that might lead to these variations.

Predictors of outcome in patients with congenital diaphragmatic hernia requiring extracorporeal membrane oxygenation

BACKGROUND

The role of extracorporeal membrane oxygenation (ECMO) in patients with congenital diaphragmatic hernia is still evolving. The use of ECMO is invasive with potential complications during instrumentation for cannulation and heparinization. There are no reliable predictors of outcome in patients requiring ECMO. We aimed to identify (a) the factors that could predict outcome and (b) the incidence and relation of complications during ECMO to outcome.

METHODS

"Pre" ECMO (age, sex, birth weight, blood gasses, and ventilator settings) and "on" ECMO variables (mode of ECMO, use of nitric oxide, surfactant, liquid ventilation, inotropes, timing of repair, and complications on ECMO) were analyzed to identify predictors of outcome.

RESULTS

Fifty-two patients were included. The overall survival was 58%. Mean duration of ECMO (181 +/- 120 vs 317 +/- 156 hours, P = .001), use of nitric oxide (6 vs 10, P = .049), and renal complications (4 vs 14; P < .001) differed between survivors and nonsurvivors. The survival of patients requiring ECMO support for more than 2 weeks is significantly lower than that of patients requiring ECMO support for less than 2 weeks (18% vs 68%, P = .005). Multiple logistic regression revealed ECMO duration of 2 weeks or more and renal complications to be associated with mortality.

CONCLUSION

No pre-ECMO variable could be identified as predictor of mortality. Prolonged duration of ECMO and renal complications on ECMO were independently associated with mortality.

Pseudocalcification on chest CT scan

Liquid ventilation with perfluorocarbons is used in severe respiratory failure that cannot be managed by conventional methods. Very little is known about the use of liquid ventilation in paediatric patients with respiratory failure and there are no reports describing the distribution and excretion of perfluorocarbons in paediatric patients with severe respiratory failure. The aim of this report is to highlight the prolonged retention of perfluorocarbons in a paediatric patient, mimicking pulmonary calcification and misleading the interpretation of the chest CT scan. A 10-year-old girl was admitted to our intensive care unit with severe respiratory failure due to miliary tuberculosis. Extracorporeal membrane oxygenation (ECMO) was used to support gas exchange and partial liquid ventilation (PLV) with perfluorodecalin was used to aid in oxygenation, lavage the lungs and clear thick secretions. The patient developed a pneumothorax (fluorothorax) on the next day and PLV was discontinued. Multiple bronchoalveolar lavages were performed to clear thick secretions. With no improvement in lung function over the next month a CT scan of the chest was performed. This revealed extensive pulmonary fibrosis and multiple high attenuation lesions suggestive of pulmonary calcification. To exclude perfluorodecalin as the cause for high attenuation lesions, a sample of perfluorodecalin was scanned to estimate the Hounsfield unit density, which was similar to the density of high attenuation lesions on chest CT scan. High-density opacification should be interpreted with caution, especially following liquid ventilation.

Extracorporeal membrane oxygenation and extracorporeal albumin dialysis in pediatric patients with sepsis and multi-organ dysfunction syndrome

Extracorporeal membrane oxygenation (ECMO) is used in managing patients with potentially reversible cardio-respiratory failure refractory to conventional methods. Multiorgan dysfunction syndrome (MODS), usually due to sepsis, remains the main cause of mortality in such patients. We report a series of six pediatric patients with sepsis-induced MODS where extracorporeal albumin dialysis (EAD) was used while the patients were on ECMO. The age of the patients ranged between 1 month and 17 years. The mean pediatric index of mortality (PIM) score at admission was 67.5%. All these patients further deteriorated with MODS and EAD was used as rescue therapy. At institution of EAD, 4 patients had dysfunction of 4 organs and 2 patients had dysfunction of 5 organs. The number of EAD cycles ranged between 1 and 3. Three out of the 6 patients (50%) survived to discharge from the intensive care unit and two of the six patients (33%) survived to hospital discharge. According to our previous experience and published results, all these patients would have been expected to die. The present results suggest that EAD may prove to have a role in the treatment of pediatric patients with sepsis-induced MODS. Further research is required to identify the group of patients who would benefit most by EAD as well as understand the clearance of inflammatory mediators and other mechanisms involved with the use of EAD.

Factors influencing the outcome of paediatric cardiac surgical patients during extracorporeal circulatory support

BACKGROUND

Veno-arterial extracorporeal membrane oxygenation (ECMO) is a common modality of circulatory assist device used in children. We assessed the outcome of children who had ECMO following repair of congenital cardiac defects (CCD) and identified the risk factors associated with hospital mortality.

METHODS

From April 1990 to December 2003, 53 patients required ECMO following surgical correction of CCD. Retrospectively collected data was analyzed with univariate and multivariate logistic regression analysis.

RESULTS

Median age and weight of the patients were 150 days and 5.4 kgs respectively. The indications for ECMO were low cardiac output in 16, failure to wean cardiopulmonary bypass in 13, cardiac arrest in 10 and cardio-respiratory failure in 14 patients. The mean duration of ECMO was 143 hours. Weaning off from ECMO was successful in 66% and of these 83% were survival to hospital-discharge. 37.7% of patients were alive for the mean follow-up period of 75 months. On univariate analysis, arrhythmias, ECMO duration >168 hours, bleeding complications, renal replacement therapy on ECMO, arrhythmias and cardiac arrest after ECMO were associated with hospital mortality.On multivariate analysis, abnormal neurology, bleeding complications and arrhythmias after ECMO were associated with hospital mortality. Extra and intra-thoracic cannulations were used in 79% and 21% of patients respectively and extra-thoracic cannulation had significantly less bleeding complications (p = 0.031).

CONCLUSION

ECMO provides an effective circulatory support following surgical repair of CCD in children. Extra-thoracic cannulation is associated with less bleeding complications. Abnormal neurology, bleeding complications on ECMO and arrhythmias after ECMO are poor prognostic indicators for hospital survival.

CESAR: conventional ventilatory support vs extracorporeal membrane oxygenation for severe adult respiratory failure

BACKGROUND

An estimated 350 adults develop severe, but potentially reversible respiratory failure in the UK annually. Current management uses intermittent positive pressure ventilation, but barotrauma, volutrauma and oxygen toxicity can prevent lung recovery. An alternative treatment, extracorporeal membrane oxygenation, uses cardio-pulmonary bypass technology to temporarily provide gas exchange, allowing ventilator settings to be reduced. While extracorporeal membrane oxygenation is proven to result in improved outcome when compared to conventional ventilation in neonates with severe respiratory failure, there is currently no good evidence from randomised controlled trials to compare these managements for important clinical outcomes in adults, although evidence from case series is promising.

METHODS/DESIGN

The aim of the randomised controlled trial of Conventional ventilatory support vs extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR) is to assess whether, for patients with severe, but potentially reversible, respiratory failure, extracorporeal membrane oxygenation will increase the rate of survival without severe disability ('confined to bed' and 'unable to wash or dress') by six months post-randomisation, and be cost effective from the viewpoints of the NHS and society, compared to conventional ventilatory support. Following assent from a relative, adults (18-65 years) with severe, but potentially reversible, respiratory failure (Murray score >/= 3.0 or hypercapnea with pH < 7.2) will be randomised for consideration of extracorporeal membrane oxygenation at Glenfield Hospital, Leicester or continuing conventional care in a centre providing a high standard of conventional treatment. The central randomisation service will minimise by type of conventional treatment centre, age, duration of high pressure ventilation, hypoxia/hypercapnea, diagnosis and number of organs failed, to ensure balance in key prognostic variables. Extracorporeal membrane oxygenation will not be available for patients meeting entry criteria outside the trial. 180 patients will be recruited to have 80% power to be able to detect a one third reduction in the primary outcome from 65% at 5% level of statistical significance (2-sided test). Secondary outcomes include patient morbidity and health status at 6 months.

DISCUSSION

Analysis will be based on intention to treat. A concurrent economic evaluation will also be performed to compare the costs and outcomes of both treatments.

Standards of reporting of randomized controlled trials in general surgery: can we do better?

OBJECTIVE

To evaluate the quality of reporting of surgical randomized controlled trials published in surgical and general medical journals using Jadad score, allocation concealment, and adherence to CONSORT guidelines and to identify factors associated with good quality.

SUMMARY BACKGROUND DATA

Randomized controlled trials (RCTs) provide the best evidence about the relative effectiveness of different interventions. Improper methodology and reporting of RCTs can lead to erroneous conclusions about treatment effects, which may mislead decision-making in health care at all levels.

METHODS

Information was obtained on RCTs published in 6 general surgical and 4 general medical journals in the year 2003. The quality of reporting of RCTs was assessed under masked conditions using allocation concealment, Jadad score, and a CONSORT checklist devised for the purpose.

RESULTS

Of the 69 RCTs analyzed, only 37.7% had a Jadad score of > or =3, and only 13% of the trials clearly explained allocation concealment. The modified CONSORT score of surgical trials reported in medical journals was significantly higher than those reported in surgical journals (Mann-Whitney U test, P < 0.001). Overall, the modified CONSORT score was higher in studies with higher author numbers (P = 0.03), multicenter studies (P = 0.002), and studies with a declared funding source (P = 0.022).

CONCLUSION

The overall quality of reporting of surgical RCTs was suboptimal. There is a need for improving awareness of the CONSORT statement among authors, reviewers, and editors of surgical journals and better quality control measures for trial reporting and methodology.

Improving the quality of reporting randomized controlled trials in cardiothoracic surgery: the way forward

OBJECTIVE

To evaluate the quality of reporting of randomized controlled trials in cardiothoracic surgery, to identify factors associated with good reporting quality, and to assess the awareness of the Consolidated Standards for Reporting of Trials statement and ascertain the views of authors reporting randomized controlled trials on the difficulties in conducting randomized controlled trials and the possible ways to further improve the reporting quality of randomized controlled trials in cardiothoracic surgery.

METHODS

Randomized controlled trials of cardiothoracic surgery published in principal cardiothoracic and 4 general medical journals in 2003 were included. The quality of reporting of randomized controlled trials was assessed by using allocation concealment, the Jadad score, and a Consolidated Standards for Reporting of Trials checklist devised for the purpose. A questionnaire survey of authors reporting randomized controlled trials in principal cardiothoracic journals in 2003 was conducted.

RESULTS

The overall reporting quality of the 64 randomized controlled trials included in the analysis was suboptimal as assessed by the 3 methods adopted. Most of the authors (63.5%) were not aware of the Consolidated Standards for Reporting of Trials statement; however, awareness was not associated with reporting quality. More than 65% of the authors responded that conducting randomized controlled trials in surgical specialties was difficult, and the main difficulties were blinding and obtaining a large-enough sample size to detect statistically significant differences. Fifty-four percent of the authors responded that endorsement of the Consolidated Standards for Reporting of Trials statement by the cardiothoracic journals may improve the reporting quality.

CONCLUSIONS

The quality of reporting randomized controlled trials in cardiothoracic surgery is suboptimal. Endorsement of the Consolidated Standards for Reporting of Trials statement by the cardiothoracic journals may improve the quality of reporting.

Coronary endarterectomy in the current era

PURPOSE OF REVIEW

The increasing incidence of diffuse coronary artery disease in the current era challenges cardiac surgeons in accomplishing their goal of complete revascularisation. Although coronary endarterectomy is used with encouraging results in most institutions, there remains some controversy in its indications, technique, and results. The purpose of this review is to highlight the important evolutions of technique in the recent past.

RECENT FINDINGS

Despite the increased risk factors and comorbidities in patients presenting with diffuse coronary artery disease requiring coronary endarterectomy, the results of coronary endarterectomy are improving inline with the improvements in the results of conventional coronary artery bypass grafting surgery. The improving results of coronary endarterectomy in the left anterior descending artery are further clarified. The intra- and postoperative use of prostacyclin has been shown to be effective in reducing mortality and perioperative myocardial infarction. The technique of open coronary endarterectomy with on-lay patch bypass grafting has been shown to be safe and effective in reducing mortality and improving patency as compared with the closed (traction) method of coronary endarterectomy. The use of coronary endarterectomy was also found to be effective in the treatment of in-stent restenosis in the setting of diffuse coronary artery disease. The results of off-pump coronary endarterectomy are encouraging and comparable with the conventional coronary endarterectomy using cardiopulmonary bypass.

SUMMARY

With the increasing incidence of diffuse coronary artery disease and improving results of coronary endarterectomy, it is vital for cardiac surgeons to have coronary endarterectomy in their armamentarium to achieve complete coronary revascularisation.

Successful use of venovenous extracorporeal membrane oxygenation in accidental hypothermic cardiac arrest

Cardiopulmonary bypass is usually used for rewarming and for providing cardiac support in patients with severe hypothermia and cardiovascular instability. We report the first case of accidental severe hypothermia associated with prolonged cardiac arrest that was successfully managed by venovenous extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation with lepirudin anticoagulation for Wegener's granulomatosis with heparin-induced thrombocytopenia

Venovenous extracorporeal membrane oxygenation with lepirudin anticoagulation was successfully used for a complicated case of Wegener's granulomatosis and heparin-induced thrombocytopenia. Interestingly, a linear correlation was found between activated partial thromboplastin time and activated clotting time during lepirudin anticoagulation.

Coronary endarterectomy: impact on morbidity and mortality when combined with coronary artery bypass surgery

BACKGROUND

The results of coronary endarterectomy (CE) performed in addition to coronary artery bypass grafting (CABG) have been controversial. We aimed to examine the impact of CE performed in addition to CABG when compared with CABG alone in our unit.

METHODS

Patients who had CABG between January 1995 and December 2001 were included. They were divided into two groups, the CABG-only group and CABG and CE group. The following outcomes were compared: perioperative myocardial infarction, postoperative ventricular arrhythmias, cerebrovascular accident, renal impairment, and early mortality.

RESULTS

Of 5,782 patients who underwent CABG, 461 patients (8.6%) required CE in addition to CABG. There was a higher mortality and incidence of postoperative renal impairment in the group of patients who had CABG and CE, with no significant difference in other outcomes. However, the patients in the CABG and CE group had a higher incidence of male sex, previous myocardial infarctions, preoperative renal impairment, and poor left ventricular function, with longer cross-clamp and cardiopulmonary bypass times than in the CABG-only patients. Although female sex, renal impairment, nonelective surgery, impaired left ventricular function, and peripheral vascular disease were associated with increased mortality in all the patients, and use of statins and aspirin was associated with a reduction in mortality, CE was not a predictor of mortality. Furthermore, on propensity scores analysis, CE was not associated with increased mortality.

CONCLUSIONS

Coronary endarterectomy when combined with CABG seemed to be associated with a higher mortality than isolated CABG in our study groups, but this is related to comorbidities of these patients rather than the CE.

Surgical approach for pericardiectomy: a comparative study between median sternotomy and left anterolateral thoracotomy

Pericardiectomy is the definitive treatment for constrictive pericarditis but the best surgical approach remains controversial. In this study we compared the results of pericardiectomy performed on 36 patients with constrictive pericarditis between 1995 and 2001. Pericardiectomy was performed by median sternotomy in 15 patients and by left anterolateral thoracotomy in 21 patients. All patients were reviewed at 6 weeks post operatively. Both groups of patients were similar in age, sex distribution, NYHA shortness of breath status, aetiology, presenting symptoms and duration of symptoms. Mortality was similar in the two groups with three deaths (14.2%) in the thoracotomy group and two deaths (13.3%) in the median sternotomy group. NYHA status improved in both thoracotomy (3.0+/-0.8 to 1.6+/-0.7; P=3.3x10(-6)) and median sternotomy (2.9+/-0.7 to 1.5+/-0.6; P=2.8x10(-5)) groups. The degree of improvement was not significant between the two groups (P=0.63). In addition ionotropic support and postoperative hospital stay were similar between the two groups. There was a higher incidence of wound infections (23.8 versus 6.6%; P=0.13) and pulmonary complications (23.8 versus 13.3%; P=0.33) associated with thoracotomy. In conclusion pericardiectomy improves NYHA status in all patients and mortality rates are similar in both the approaches.