Simon Baudouin

Survival in Duchenne muscular dystrophy: improvements in life expectancy since 1967 and the impact of home nocturnal ventilation

We reviewed the notes of 197 patients with Duchenne muscular dystrophy whose treatment was managed at the Newcastle muscle centre from 1967 to 2002, to determine whether survival has improved over the decades and whether the impact of nocturnal ventilation altered the pattern of survival. Patients were grouped according to the decade of death and whether or not they were ventilated. Kaplan Meier survival analyses showed significant decade on decade improvement in survival. Mean age of death in the 1960s was 14.4 years, whereas for those ventilated since 1990 it was 25.3 years. Cardiomyopathy significantly shortened life expectancy from 19 years to a mean age of 16.9 years. Better coordinated care probably improved the chances of survival to 25 years from 0% in the 1960s to 4% in the 1970s and 12% in the 1980s, but the impact of nocturnal ventilation has further improved this chance to 53% for those ventilated since 1990.

Mitochondrial DNA and survival after sepsis: a prospective study

BACKGROUND Human genome evolution has been shaped by infectious disease. Although most genetic studies have focused on the immune system, recovery after sepsis is directly related to physiological reserve that is critically dependent on mitochondrial function. We investigated whether haplogroup H, the most common type of mitochondrial DNA (mtDNA) in Europe, contributes to the subtle genetic variation in survival after sepsis. METHODS In a prospective study, we included 150 individuals who were sequentially admitted to the intensive care unit in a hospital in Newcastle upon Tyne, UK. After clinical data were obtained, patients underwent mtDNA haplotyping by analysis with PCR and restriction fragment length polymorphism. As endpoints, we used death during the 6-month period or survival at 6 months. FINDINGS Follow-up was complete for all study participants, although the haplotype of two patients could not be reliably determined. On admission to the intensive care unit, the frequency of mtDNA haplogroup H in study patients did not differ between study patients admitted with severe sepsis and 542 age-matched controls from the northeast of England. MtDNA haplogroup H was a strong independent predictor of outcome during severe sepsis, conferring a 2.12-fold (95% CI 1.02-4.43) increased chance of survival at 180 days compared with individuals without the haplogroup H. INTERPRETATION Although haplogroup H is the most recent addition to the group of European mtDNA, paradoxically it is also the most common. Increased survival after sepsis provides one explanation for this observation. MtDNA haplotyping offers a new means of risk stratification of patients with severe infections, which suggests new avenues for therapeutic intervention.

TISS and mortality after discharge from intensive care

Objective: To examine the effect of high levels of pre-intensive care unit (ICU) discharge care, as assessed by the Therapeutic Intervention Scoring System (TISS), on subsequent hospital mortality.¶Design: A 1-year prospective, observational study.¶Setting: The ICU and wards of a university teaching hospital with no high dependency facility (HDU).¶Patients: A total of 283 patients were discharged to hospital wards between July 1997 and June 1998.¶Results: 11 % of all ICU discharges subsequently died in hospital. Patients discharged with a TISS of 20 or greater had a 21.4 % mortality compared to 3.7 % for those with a TISS of less than 10. Increasing age, Acute Physiology Score (APS) on admission and male sex were also significantly associated with post-discharge death.¶Conclusions: In a hospital without HDU facilities, patients who are receiving HDU levels of care on discharge from the ICU have a high in-hospital mortality.

Nutritional support in critical care

Despite the key role of nutrition in health and the almost universal use of supplemental feeding in the ICU, there is a lack of high-quality evidence to guide clinical practice. Enteral nutrition is superior to TPN in almost all circumstances and most patients in the ICU can be fed successfully by this route. There is little evidence to support the use of special feeds and the role of immunonutrients remains unproven. Nutritional support cannot completely prevent the adverse effects of catabolic illness and overfeeding should be avoided.

Action of carbon dioxide on hypoxic pulmonary vasoconstriction in the rat lung: evidence against specific endothelium-derived relaxing factor-mediated vasodilation.

ObjectivesThe effect of hypercapnia on pulmonary vascular tone is controversial with evidence for both a vasoconstrictor and vasodilator action. The objective of this study was to investigate the possibility that this dual response to CO2 could be explained by a direct constrictor action on smooth muscle and an indirect dilator action via the release of endothelium-derived relaxing factor. The effect of ventilation with hypercapnia (Fico2 0.15) on pulmonary pressor response to hypoxia (Fio2 0.3) was investigated. DesignProspective, randomized study. SettingThe National Heart and Lung Institute, UK. SubjectsThe isolated, blood-perfused rat lung. InterventionsAngiotensin-II and a blocker of endothelium-derived relaxing factor synthesis, NG-monomethyl-L-arginine (L-NMMA). Measurements and Main ResultsThe vasomotor effect of hypercapnia depended on pulmonary arterial pressure. Under resting tone, CO2 acted as a mild constrictor (change in mean pulmonary arterial pressure from 14 ± 2 to 15 ± 2 mm Hg, n = 4; p < .05. At increased tone, induced either by hypoxia or Angiotensin-II, CO2 was a vasodilator. Thus, hypoxia increased mean pulmonary arterial pressure from 17 ± 2 to 32 ± 2 mm Hg (n = 8;p < .01), but simultaneous ventilation with hypoxia and hypercapnia reduced this by 16 ± 1% (p < .01). Angiotensin-II (1 μg) increased pulmonary arterial pressure from 14 ± 2 to 39 ± 5 mm Hg (n = 8; p < .01), but with hypercapnia, this angiotensin-induced pulmonary vasoconstriction was reduced by 18 ± 6% (p < .001). The reduction in hypoxic pulmonary vasoconstriction induced by hypercapnia was not significantly different from that seen with Angiotensin-II hypercapnia. Blocking endothelium-derived relaxing factor synthesis using 30 μM NG-monomethyl-L-arginine did not significantly change either basal pulmonary arterial pressure or the response to hypercapnia, but increased hypoxic pulmonary vasoconstrictor by 24 ± 4% (n = 4;p < .01). There was no significant difference between the change in hypoxic pulmonary vasoconstriction induced by hypercapnia after saline control (21 ± 8% decrease) and the change in hypoxic pulmonary vasoconstriction caused by CO2 after 30 μM L-NMMA (25 ± 10% decrease, p < .05, n = 8). ConclusionEndothelium-derived relaxing factor seems unlikely to specifically modulate CO2-induced vasodilation in the rat pulmonary circulation. (Crit Care Med 1993; 21:740–746)

Diagnostic accuracy of pulmonary host inflammatory mediators in the exclusion of ventilator-acquired pneumonia

Background Excessive use of empirical antibiotics is common in critically ill patients. Rapid biomarker-based exclusion of infection may improve antibiotic stewardship in ventilator-acquired pneumonia (VAP). However, successful validation of the usefulness of potential markers in this setting is exceptionally rare. Objectives We sought to validate the capacity for specific host inflammatory mediators to exclude pneumonia in patients with suspected VAP. Methods A prospective, multicentre, validation study of patients with suspected VAP was conducted in 12 intensive care units. VAP was confirmed following bronchoscopy by culture of a potential pathogen in bronchoalveolar lavage fluid (BALF) at >104 colony forming units per millilitre (cfu/mL). Interleukin-1 beta (IL-1β), IL-8, matrix metalloproteinase-8 (MMP-8), MMP-9 and human neutrophil elastase (HNE) were quantified in BALF. Diagnostic utility was determined for biomarkers individually and in combination. Results Paired BALF culture and biomarker results were available for 150 patients. 53 patients (35%) had VAP and 97 (65%) patients formed the non-VAP group. All biomarkers were significantly higher in the VAP group (p<0.001). The area under the receiver operator characteristic curve for IL-1β was 0.81; IL-8, 0.74; MMP-8, 0.76; MMP-9, 0.79 and HNE, 0.78. A combination of IL-1β and IL-8, at the optimal cut-point, excluded VAP with a sensitivity of 100%, a specificity of 44.3% and a post-test probability of 0% (95% CI 0% to 9.2%). Conclusions Low BALF IL-1β in combination with IL-8 confidently excludes VAP and could form a rapid biomarker-based rule-out test, with the potential to improve antibiotic stewardship.

Developing the first national antimicrobial prescribing and stewardship competences

Antimicrobial resistance is a national and worldwide threat to the future of healthcare. Educating both healthcare staff and the public in the prudent use of antimicrobials is an essential part of antimicrobial stewardship programmes that aim to contain and control resistance and preserve the usefulness of currently available antibiotics. Using current available evidence, regulatory documents and national antimicrobial stewardship guidance for primary and secondary care, five dimensions for antimicrobial prescribing and stewardship competences have been developed in England, through an independent multiprofessional group led by the Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infection (ARHAI) of the Department of Health (England). They are designed to complement the generic competency framework for all prescribers from the UK National Prescribing Centre (now part of National Institute for Health and Care Excellence) and are relevant to all independent prescribers, including doctors, dentists and non-medical practitioners. The antimicrobial prescribing and stewardship competences published jointly by ARHAI and PHE in 2013 are believed to be the first of their kind. Implementation of these competences will be an important contribution to the delivery of the UK governments 5 year Antimicrobial Resistance Strategy.

DiPALS: Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis - a randomised controlled trial.

BACKGROUND Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease resulting in death, usually from respiratory failure, within 2-3 years of symptom onset. Non-invasive ventilation (NIV) is a treatment that when given to patients in respiratory failure leads to improved survival and quality of life. Diaphragm pacing (DP), using the NeuRx/4(®) diaphragm pacing system (DPS)™ (Synapse Biomedical, Oberlin, OH, USA), is a new technique that may offer additional or alternative benefits to patients with ALS who are in respiratory failure. OBJECTIVE The Diaphragm Pacing in patients with Amyotrophic Lateral Sclerosis (DiPALS) trial evaluated the effect of DP on survival over the study duration in patients with ALS with respiratory failure. DESIGN The DiPALS trial was a multicentre, parallel-group, open-label, randomised controlled trial incorporating health economic analyses and a qualitative longitudinal substudy. PARTICIPANTS Eligible participants had a diagnosis of ALS (ALS laboratory-supported probable, clinically probable or clinically definite according to the World Federation of Neurology revised El Escorial criteria), had been stabilised on riluzole for 30 days, were aged ≥ 18 years and were in respiratory failure. We planned to recruit 108 patients from seven UK-based specialist ALS or respiratory centres. Allocation was performed using 1 : 1 non-deterministic minimisation. INTERVENTIONS Participants were randomised to either standard care (NIV alone) or standard care (NIV) plus DP using the NeuRX/4 DPS. MAIN OUTCOME MEASURES The primary outcome was overall survival, defined as the time from randomisation to death from any cause. Secondary outcomes were patient quality of life [assessed by European Quality of Life-5 Dimensions, three levels (EQ-5D-3L), Short Form questionnaire-36 items and Sleep Apnoea Quality of Life Index questionnaire]; carer quality of life (EQ-5D-3L and Caregiver Burden Inventory); cost-utility analysis and health-care resource use; tolerability and adverse events. Acceptability and attitudes to DP were assessed in a qualitative substudy. RESULTS In total, 74 participants were randomised into the trial and analysed, 37 participants to NIV plus pacing and 37 to standard care, before the Data Monitoring and Ethics Committee advised initial suspension of recruitment (December 2013) and subsequent discontinuation of pacing (on safety grounds) in all patients (June 2014). Follow-up assessments continued until the planned end of the study in December 2014. The median survival (interquartile range) was 22.5 months (lower quartile 11.8 months; upper quartile not reached) in the NIV arm and 11.0 months (6.7 to 17.0 months) in the NIV plus pacing arm, with an adjusted hazard ratio of 2.27 (95% confidence interval 1.22 to 4.25; p = 0.01). CONCLUSIONS Diaphragmatic pacing should not be used as a routine treatment for patients with ALS in respiratory failure. FUTURE WORK It may be that certain population subgroups benefit from DP. We are unable to explain the mechanism behind the excess mortality in the pacing arm, something the small trial size cannot help address. Future research should investigate the mechanism by which harm or benefit occurs further. TRIAL REGISTRATION Current Controlled Trials ISRCTN53817913. FUNDING This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 45. See the HTA programme website for further project information. Additional funding was provided by the Motor Neurone Disease Association of England, Wales and Northern Ireland.

Sleep-related breathing disorders following discharge from intensive care

Objectives: To determine the incidence of sleep-related breathing disorders and nocturnal hypoxaemia in patients discharged from ICU following prolonged mechanical ventilation.¶Design: Prospective, consecutive patient observational study.¶Setting: The medical and surgical wards of a University Hospital.¶Patients and participants: Fifteen consecutive, adult patients discharged from the ICU who had received more than 48 h of mechanical ventilation were studied. Ten healthy volunteers acted as controls.¶Measurements and results: Overnight, multi-channel pneumographic studies were performed on all patients and controls. Chest and abdominal wall movement, air flow, oxygen saturation and snoring were continuously recorded. Data was analysed by both visual inspection of the traces and by computer-based algorithms. An apnoea/hypopnoea index was calculated for each patient and volunteer. Volunteers had an apnoea/hypopnoea index of less than 5 and had no episodes of nocturnal oxygen desaturation (SaO2 < 90 %). Despite oxygen therapy 13/15 patients had episodes of desaturation and 9/15 spent more than 2 h with an SaO2 < 90 %. Eleven patients had an abnormal apnoea/hypopnoea index (range 5–34 events/h). Four patients had predominantly obstructive events while 7 primarily had hypopnoeas.¶Conclusions: Significant overnight oxygen desaturation is common in patients discharged from ICU who have received prolonged mechanical ventilation. This group also has a significant incidence of sleep-related breathing disorders and this mechanism is likely to be important in the pathogenesis of the hypoxaemia.

Intensive versus standard physical rehabilitation therapy in the critically ill (EPICC): a multicentre, parallel-group, randomised controlled trial

Background Early physical rehabilitation in the intensive care unit (ICU) has been shown to improve short-term clinical outcomes but long-term benefit has not been proven and the optimum intensity of rehabilitation is not known. Methods We conducted a randomised, parallel-group, allocation-concealed, assessor-blinded, controlled trial in patients who had received at least 48 hours of invasive or non-invasive ventilation. Participants were randomised in a 1:1 ratio, stratified by admitting ICU, admission type and level of independence. The intervention group had a target of 90 min physical rehabilitation per day, the control group a target of 30 min per day (both Monday to Friday). The primary outcome was the Physical Component Summary (PCS) measure of SF-36 at 6 months. Results We recruited 308 participants over 34 months: 150 assigned to the intervention and 158 to the control group. The intervention group received a median (IQR) of 161 (67–273) min of physical rehabilitation on ICU compared with 86 (31–139) min in the control group. At 6 months, 62 participants in the intervention group and 54 participants in the control group contributed primary outcome data. In the intervention group, 43 had died, 11 had withdrawn and 34 were lost to follow-up, while in the control group, 56 had died, 5 had withdrawn and 43 were lost to follow-up. There was no difference in the primary outcome at 6 months, mean (SD) PCS 37 (12.2) in the intervention group and 37 (11.3) in the control group. Conclusions In this study, ICU-based physical rehabilitation did not appear to improve physical outcomes at 6 months compared with standard physical rehabilitation. Trial registration number ISRCTN 20436833.