Venous blood gases in the assessment of respiratory failure in patients undergoing sleep studies: a randomized study.

STUDY OBJECTIVES: Venous blood gases (VBGs) are not consistently considered suitable surrogates for arterial blood gases (ABGs) in assessing acute respiratory failure due to variable measurement error. The physiological stability of patients with chronic ventilatory failure may lead to improved agreement in this setting. METHODS: Adults requiring ABGs for sleep or ventilation titration studies had VBGs drawn before or after each ABG, in a randomized order. Veno-arterial correlation and agreement were examined for carbon dioxide tension (PCO2), pH, oxygen tension (PO2) and oxygen saturation (SO2). RESULTS: We analyzed 115 VBG-ABG pairs from 61 patients. Arterial and venous measures were correlated (with p<0.05) for PCO2 (r=0.84) and pH (r=0.72), but not for PO2 or SO2. Adjusted mean veno-arterial differences (95% limits of agreement) were +5.0mmHg (-4.4 to +14.4) for PCO2; -0.02 (-0.09 to +0.04) for pH; -34.3mmHg (-78.5 to +10.0) for PO2; and -23.9% (-61.3 to +13.5) for SO2. VBGs obtained from the dorsal hand demonstrated a lower mean PCO2 veno-arterial difference (p<0.01). A venous PCO2 threshold of ≥45.8mmHg was >95% sensitive for arterial hypercapnia, so measurements below this can exclude the diagnosis without an ABG. A venous PCO2 threshold of ≥53.7mmHg was >95% specific for arterial hypercapnia, so such readings can be assumed diagnostic. The area under the receiver operating characteristic curve of 0.91 indicated high discriminatory capacity. CONCLUSIONS: A venous PCO2 <45.8mmHg or ≥53.7mmHg would exclude or diagnose hypercapnia, respectively, in patients referred for sleep studies, but VBGs are poor surrogates for ABGs where precision is important. CLINICAL TRIAL REGISTRATION: Registry: Australian New Zealand Clinical Trials Register; Name: A comparison of arterial and blood gas analyses in sleep studies; Identifier: ACTRN12617000562370; URL https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372717.

Pulmonary artery sarcoma: An important mimic of pulmonary embolism-Case reports and literature review.

Pulmonary artery intimal sarcoma (PAIS) is a rare malignancy which closely mimics acute or chronic pulmonary thromboembolism. There are clinical and radiological characteristics which may raise suspicion of this important differential diagnosis. These include disproportionately low d-dimer, troponin T or NT-proBNP, as well as characteristic findings on CT pulmonary angiography such as the 'wall eclipsing sign' and an non-dependent position of filling defects in the large arteries. Prompt diagnosis avoids inappropriate anticoagulation and facilitates early surgical management which may improve prognosis. There is emerging evidence of an effective treatment paradigm with surgical resection and adjuvant chemotherapy. We present two cases of PAIS diagnosed at a single centre within a 2-year period. We review the literature and demonstrate the features at presentation in our cases which were suggestive of the diagnosis.

Inspiratory Muscle Training Improves Inspiratory Muscle Strength and Functional Exercise Capacity in Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: A Pilot Randomised Controlled Study.

BACKGROUND: Exercise intolerance is present even in the early stages of pulmonary arterial hypertension (PAH) and is associated with poorer prognosis. Respiratory muscle dysfunction is common and may contribute to exercise limitation. We sought to investigate the effects of inspiratory muscle training (IMT) to improve exercise capacity in PAH. METHODS: Adults with PAH were prospectively recruited and randomly assigned to either IMT or a control group. At baseline and after 8 weeks, assessment of respiratory muscle function, pulmonary function, neurohormonal activation, 6-minute walk distance and cardiopulmonary exercise testing variables were conducted. Inspiratory muscle strength was assessed by maximal static inspiratory pressure (PImax). The IMT group performed two cycles of 30 breaths at 30-40% of their PImax 5 days a week for 8 weeks. RESULTS: Twelve (12) PAH patients (60±14 years, 10 females) were recruited and randomised (six in the IMT group and six in the control group). After 8 weeks, the IMT group improved PImax by 31 cmH2O compared with 10 cmH2O in controls, p=0.02. Following IMT, 6-minute walk distance improved by 24.5 m in the IMT group and declined by 12 m in the controls (mean difference 36.5 m, 95% CI 3.5-69.5, p=0.03). There was no difference in peak oxygen uptake between-groups (mean difference 0.4 mL/kg/min, 95% CI -2.6 to 3.4, p=0.77). There was no difference in the mean change between-groups in neurohormonal activation or pulmonary function. CONCLUSION: In this pilot randomised controlled study, IMT improved PImax and 6-minute walk distance in PAH patients.

Peripheral venoarterial extracorporeal membrane oxygenation for severe hyperlactataemia after cardiac surgery: a pilot study.

BACKGROUND: Severe hyperlactataemia in patients after cardiac surgery is associated with poor prognosis and implies possible splanchnic hypoperfusion. Peripheral venoarterial extracorporeal membrane oxygenation (splanchnic ECMO) may be more effective at reducing lactic acidosis for these patients. OBJECTIVE: To investigate whether splanchnic ECMO attenuates hyperlactataemia and liver enzyme release in these patients, despite them having a cardiac index > 2 L/min/m2 and a mixed venous oxygen saturation > 55%. DESIGN AND PARTICIPANTS: Retrospective matched case- control study of patients treated with splanchnic ECMO for hyperlactataemia. Seven patients who had had cardiac surgery were treated with splanchnic ECMO compared with seven matched control patients. RESULTS: We observed a mean decrease in lactate levels from 9.9 mmol/L (SD, 2.9 mmol/L) to 1.4 mmol/L (SD, 0.6 mmol/L) in patients receiving 48 hours of splanchnic ECMO, compared with a mean of 10.4 mmol/L (SD, 2.8 mmol/L) to 4.4 mmol/L (SD, 5 mmol/L) during 48 hours in control patients (P < 0.0001). Normalisation of lactate levels (to < 2 mmol/L) was achieved within a mean of 16.3 hours (SD, 14.6 hours) with splanchnic ECMO, compared with 38.3 hours (SD, 23.8 hours) in the control group (P = 0.029). The median increase in alanine aminotransferase level with splanchnic ECMO was 68% (range, -84% to 2015%) compared with 158% (range: 0%-6024%) (not significant) in control patients. CONCLUSION: In a selected cohort of patients who had had cardiac surgery with severe post-operative hyperlactataemia, despite an acceptable cardiac index and a mixed venous oxygen saturation, splanchnic ECMO appeared to reduce overall lactate levels and time to normalisation of lactataemia.

Increased Number of Human Cases of Influenza Virus A(H5N1) Infection, Egypt, 2014-15.

During November 2014-April 2015, a total of 165 case-patients with influenza virus A(H5N1) infection, including 6 clusters and 51 deaths, were identified in Egypt. Among infected persons, 99% reported poultry exposure: 19% to ill poultry and 35% to dead poultry. Only 1 person reported wearing personal protective equipment while working with poultry.

Myobacterium bovis peri-prosthetic hip infection with successful prosthesis retention following intravesical BCG therapy for bladder carcinoma.

Systemic dissemination and peri-prosthetic infection of Mycobacterium bovis (M. bovis) following intravesical Bacillus Calmette-Guerin (BCG) therapy presents a rare but significant complication of treatment for non-muscle invasive bladder carcinoma. We present a patient with Mycobacterium bovis infection of a prosthetic hip nine months following BCG therapy for bladder cancer. The debridement and (implant) prosthesis retention approach in conjunction with anti-tuberculous medication (DAIR) employed in this case, allowed the same prosthesis to be retained. This case report highlights the importance of physician awareness of the possibility BCG peri-prosthetic infections.

Capacity building in national influenza laboratories--use of laboratory assessments to drive progress.

BACKGROUND: Laboratory testing is a fundamental component of influenza surveillance for detecting novel strains with pandemic potential and informing biannual vaccine strain selection. The United States (U.S.) Centers for Disease Control and Prevention (CDC), under the auspices of its WHO Collaborating Center for Influenza, is one of the major public health agencies which provides support globally to build national capacity for influenza surveillance. Our main objective was to determine if laboratory assessments supported capacity building efforts for improved global influenza surveillance. METHODS: In 2010, 35 national influenza laboratories were assessed in 34 countries, using a standardized tool. Post-assessment, each laboratory received a report with a list of recommendations for improvement. Uptake of recommendations were reviewed 3.2 mean years after the initial assessments and categorized as complete, in-progress, no action or no update. This was a retrospective study; follow-up took place through routine project management rather than at a set time-point post-assessment. WHO data on National Influenza Centre (NIC) designation, External Quality Assessment Project (EQAP) participation and FluNet reporting was used to measure laboratory capacity longitudinally and independently of the assessments. All data was further stratified by World Bank country income category. RESULTS: At follow-up, 81% of 614 recommendations were either complete (350) or in-progress (145) for 32 laboratories (91% response rate). The number of countries reporting to FluNet and the number of specimens they reported annually increased between 2005, when they were first funded by CDC, and 2010, the assessment year (p < 0.01). Improvements were also seen in EQAP participation and NIC designation over time and more so for low and lower-middle income countries. CONCLUSIONS: Assessments using a standardized tool have been beneficial to improving laboratory-based influenza surveillance. Specific recommendations helped countries identify and prioritize areas for improvement. Data from assessments helped CDC focus its technical assistance by country and region. Low and lower-middle income countries made greater improvements in their laboratories compared with upper-middle income countries. Future research could include an analysis of annual funding and technical assistance by country. Our approach serves as an example for capacity building for other diseases.

Investigating a crow die-off in January-February 2011 during the introduction of a new clade of highly pathogenic avian influenza virus H5N1 into Bangladesh.

We investigated unusual crow mortality in Bangladesh during January-February 2011 at two sites. Crows of two species, Corvus splendens and C. macrorhynchos, were found sick and dead during the outbreaks. In selected crow roosts, morbidity was ~1 % and mortality was ~4 % during the investigation. Highly pathogenic avian influenza virus H5N1 clade 2.3.2.1 was isolated from dead crows. All isolates were closely related to A/duck/India/02CA10/2011 (H5N1) with 99.8 % and A/crow/Bangladesh/11rs1984-15/2011 (H5N1) virus with 99 % nucleotide sequence identity in their HA genes. The phylogenetic cluster of Bangladesh viruses suggested a common ancestor with viruses found in poultry from India, Myanmar and Nepal. Histopathological changes and immunohistochemistry staining in brain, pancreas, liver, heart, kidney, bursa of Fabricius, rectum, and cloaca were consistent with influenza virus infection. Through our limited investigation in domesticated birds near the crow roosts, we did not identify any samples that tested positive for influenza virus A/H5N1. However, environmental samples collected from live-bird markets near an outbreak site during the month of the outbreaks tested very weakly positive for influenza virus A/H5N1 in clade 2.3.2.1-specific rRT-PCR. Continuation of surveillance in wild and domestic birds may identify evolution of new avian influenza virus and associated public-health risks.

Veillonella spondylodiscitis in a healthy 76-year-old lady.

PURPOSE: To report a case of Veillonella spondylodiscitis in a healthy 76-year-old lady. METHODS: A previously healthy 76-year-old lady presented with worsening axial back pain at the thoracolumbar junction, fever and loss of weight. Examination revealed deep tenderness over the thoracolumbar junction with painful and restricted spinal movements. The lower limb motor power, sensation and reflexes were normal. RESULTS: Radiographs of the lumbosacral spine showed evidence of spinal instability with lateral translation and loss of disc space at L1-L2. MRI scans revealed fluid intensity within the L1-L2 disc with infective debris elevating the posterior longitudinal ligament and narrowing the spinal canal. Both tissue and blood cultures were positive for the anaerobic organism, Veillonella. A staged anterior-posterior spinal surgery followed by an extended course of antibiotics resulted in the clinical improvement and normalisation of blood parameters. A review of the literature on Veillonella infections is also presented. CONCLUSION: The aim of this report is to bring Veillonella spondylodiscitis to the attention of spinal surgeons and infectious disease specialists and discuss the management options.

Quantifying recirculation in extracorporeal membrane oxygenation: a new technique validated.

RATIONALE: The efficacy of veno-venous extracorporeal membrane oxygenation is limited by the phenomenon of recirculation, which is difficult to quantify. Existing measurement techniques using readily available equipment are unsatisfactory. OBJECTIVES: 1) To compare the accuracy of measurements of recirculation made using equations comparing blood oxygen content or saturation alone at different points in an ex vivo circuit; 2) to validate a new step-change technique for quantifying recirculation in vivo. METHODS: anesthetized greyhound dogs cannulated for veno-arterial support were connected to a circuit that allowed the creation of a known level of recirculation ex vivo and blood oxygen content/saturation monitoring. In two dogs, the accuracy of measurements derived from oxygen content and oxygen saturation were compared. The potential of a new technique for measuring recirculation in vivo by comparing the oxygen content of blood sampled during oxygenator bypass to that following a step-change in circuit oxygenation was demonstrated in a veno-venous pilot study and validated in a three-dog veno-arterial study. RESULTS: Measurements made using oxygen content versus oxygen saturation showed superior correlation with true recirculation (r(2)=0.87 vs. 0.64, p<0.0001) and less proportional measurement bias (10.3% vs. 49.8%, p=0.0045). Measurements of recirculation made using a step-change in circuit oxygenation and comparing oxygen content as is required for measuring in vivo recirculation overestimated by only 18.6% (95% Cl: 3.9-33.2%) and had excellent correlation with true values (r(2)=0.89). CONCLUSIONS: 1) Measurement of recirculation using oxygen content is superior to that using oxygen saturation alone, which demonstrates significant measurement bias; 2) the novel step-change technique is a sufficiently accurate technique for the measurement of recirculation in animal models.

Extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a technique that involves oxygenation of blood outside the body, and provides support to selected patients with severe respiratory or cardiac failure. The two major ECMO modalities are venoarterial and venovenous. Data from several randomised trials support the use of ECMO in neonatal respiratory failure, and a recent randomised controlled trial of ECMO in adults has produced encouraging results. The evidence base for ECMO use in cardiac disease is developing, but progress has been slowed by considerations of clinical equipoise and evolving indications for ECMO. Advancing ECMO technology and increasing experience with ECMO techniques have improved patient outcomes, reduced complications and expanded the potential applications of ECMO. Awareness of the indications and implications of ECMO among doctors managing patients with severe but potentially reversible respiratory or cardiac failure may help facilitate better communication between health care teams and improve patient recovery.

A teaching hospital's experience applying the Pneumonia Severity Index and antibiotic guidelines in the management of community-acquired pneumonia.

BACKGROUND AND OBJECTIVES: The Pneumonia Severity Index (PSI) was developed to predict mortality in community-acquired pneumonia (CAP). It has been prospectively validated to identify patients who are at low risk of death and thereby aid in the selection of patients for outpatient management. This study assessed the compliance of medical staff at a university teaching hospital with the use of the PSI and the PSI-based local antibiotic guidelines in admitted patients. METHODS: This was a retrospective study of 137 consecutive adults admitted with a primary diagnosis of CAP between July and December 2003. Implementation of the PSI and local antibiotic guidelines occurred 4 months prior to the study period. The data collected included patient demographics, PSI parameters, patient outcomes, adherence and compliance with the PSI scoring process and local antibiotic guidelines. RESULTS: Forty per cent of all CAP admissions were patients in PSI Class I to III. The compliance with scoring the PSI was low (45 out of 137 patients; 33%), as was the accuracy of the PSI scoring (26 out of 45 patients; 58%). Compliance with the local antibiotic guidelines was 87% in patients in whom the PSI was performed. CONCLUSIONS: In admitted patients, non-adherence with the PSI admission guidelines was common. Compliance with scoring the PSI and its scoring accuracy was low. This may be due to a lack of awareness and its relative complexity. Further studies to identify potential barriers to compliance are warranted.

Early switch to oral antibiotics and early discharge guidelines in the management of community-acquired pneumonia.

BACKGROUND AND OBJECTIVE: The major cost of managing community-acquired pneumonia (CAP) relates to the duration i.v. antibiotic use and length of hospital stay (LOS). Guidelines on early switch to oral antibiotics and early discharge from hospital may help to achieve a unified approach to managing CAP. The aim of this study was to assess the benefits and safety of these guidelines in an Australian respiratory medicine unit. METHODS: This prospective study included consecutive patients admitted with a diagnosis of CAP over a 6-month period. Early switch to oral antibiotics and early discharge guidelines were implemented one month prior to the evaluation period. Comparison was made to a retrospective control group admitted before the guidelines were implemented. Data collection included patient demographics, clinical and outcome parameters, duration of i.v. antibiotics and LOS. Thirty-day outcomes on patient safety and satisfaction were collected from the prospective group. RESULTS: One hundred and twenty-five patients in the prospective group were compared to 100 patients in the controls. Baseline characteristics were similar between the comparison groups. Both the mean duration of i.v. antibiotics used (3.38 +/- 0.22 vs. 3.99 +/- 0.28 days, P = 0.03) and LOS (7.62 +/- 0.60 vs. 8.36 +/- 0.55 days, P = 0.04) were significantly shorter in the prospective group. Thirty-day readmission rate was 6% and patient self-reported overall satisfaction was 93.9% in those who were followed up. CONCLUSIONS: The use of early switch and early discharge guidelines for CAP reduced the duration of i.v. antibiotics and LOS while maintaining high levels of safety and patient satisfaction.