Mild Hypoxemia Research Articles

Effects of Acute Systemic Hypoxia and Hypercapnia on Brain Damage in a Rat Model of Hypoxia-Ischemia.

Therapeutic hypercapnia has the potential for neuroprotection after global cerebral ischemia. Here we further investigated the effects of different degrees of acute systemic hypoxia in combination with hypercapnia on brain damage in a rat model of hypoxia and ischemia. Adult wistar rats underwent unilateral common carotid artery (CCA) ligation for 60 min followed by ventilation with normoxic or systemic hypoxic gas containing 11%O2,13%O2,15%O2 and 18%O2 (targeted to PaO2 30–39 mmHg, 40–49 mmHg, 50–59 mmHg, and 60–69 mmHg, respectively) or systemic hypoxic gas containing 8% carbon dioxide (targeted to PaCO2 60–80 mmHg) for 180 min. The mean artery pressure (MAP), blood gas, and cerebral blood flow (CBF) were evaluated. The cortical vascular permeability and brain edema were examined. The ipsilateral cortex damage and the percentage of hippocampal apoptotic neurons were evaluated by Nissl staining and terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-biotin nick end labeling (TUNEL) assay as well as flow cytometry, respectively. Immunofluorescence and western blotting were performed to determine aquaporin-4 (AQP4) expression. In rats treated with severe hypoxia (PaO2 < 50 mmHg), hypercapnia augmented the decline of MAP with cortical CBF and damaged blood–brain barrier permeability (p < 0.05). In contrast, in rats treated with mild to moderate hypoxia (PaO2 > 50 mmHg), hypercapnia protected against these pathophysiological changes. Moreover, hypercapnia treatment significantly reduced brain damage in the ischemic ipsilateral cortex and decreased the percentage of apoptotic neurons in the hippocampus after the CCA ligated rats were exposed to mild or moderate hypoxemia (PaO2 > 50 mmHg); especially under mild hypoxemia (PaO2 > 60 mmHg), hypercapnia significantly attenuated the expression of AQP4 protein with brain edema (p < 0.05). Hypercapnia exerts beneficial effects under mild to moderate hypoxemia and augments detrimental effects under severe hypoxemia on brain damage in a rat model of hypoxia-ischemia.

The Impact of Hypoxaemia on the Outcome in Liver Cirrhosis.

Prognostic factors for poor evolution are critical in the setting of limited access to liver transplantation for patients with cirrhosis. We aimed to investigate the impact of hypoxaemia on the outcome in cirrhosis and the evolution of arterial oxygen tension during long-term follow-up in these patients. Consecutive cirrhotic patients were prospectively enroled and followed-up in our tertiary referral center. Clinical features, biological tests, arterial blood gases, NT-proBNP levels, pulse oximetry measurements, 12-lead ECG, and transthoracic contrast echocardiography were documented on enrolment. The main outcomes were death and decompensation due to liver disease. 87 cirrhotic patients were included in the analysis and followed-up for a mean of 16 months. At enrolment, 27 (31%) patients were hypoxaemic, 19 had hepatopulmonary syndrome (HPS), but only 6 of those who were sampled at follow-up had persistent hypoxaemia. During the study period, 22 patients died of liver-related complications. Nine of them (41%) were hypoxaemic on enrolment but none had severe hypoxaemia. Hypoxaemia present at enrollment was not a risk factor for death (p=0.29) or decompensation of liver disease (p=0.7). A higher MELD score at baseline or increase during follow-up was a risk factor for death (p=0.02) and correlated with the presence of hypoxaemia. Normalization of the arterial oxygen levels was accompanied by a significant decrease in NT-proBNP (83 pg/ml vs 0 pg/mL, p=0.023). Mild and moderate hypoxaemia was frequent in our patients but was not associated with adverse outcome in cirrhosis. Repeated arterial blood gas sampling is advisable, especially in patients diagnosed with hepatopulmonary syndrome.

Acute lung injury and persistent small airway disease in a rabbit model of chlorine inhalation

Chlorine is a pulmonary toxicant to which humans can be exposed through accidents or intentional releases. Acute effects of chlorine inhalation in humans and animal models have been well characterized, but less is known about persistent effects of acute, high-level chlorine exposures. In particular, animal models that reproduce the long-term effects suggested to occur in humans are lacking. Here, we report the development of a rabbit model in which both acute and persistent effects of chlorine inhalation can be assessed. Male New Zealand White rabbits were exposed to chlorine while the lungs were mechanically ventilated. After chlorine exposure, the rabbits were extubated and were allowed to survive for up to 24h after exposure to 800ppm chlorine for 4min to study acute effects or up to 7days after exposure to 400ppm for 8min to study longer term effects. Acute effects observed 6 or 24h after inhalation of 800ppm chlorine for 4min included hypoxemia, pulmonary edema, airway epithelial injury, inflammation, altered baseline lung mechanics, and airway hyperreactivity to inhaled methacholine. Seven days after recovery from inhalation of 400ppm chlorine for 8min, rabbits exhibited mild hypoxemia, increased area of pressure–volume loops, and airway hyperreactivity. Lung histology 7days after chlorine exposure revealed abnormalities in the small airways, including inflammation and sporadic bronchiolitis obliterans lesions. Immunostaining showed a paucity of club and ciliated cells in the epithelium at these sites. These results suggest that small airway disease may be an important component of persistent respiratory abnormalities that occur following acute chlorine exposure. This non-rodent chlorine exposure model should prove useful for studying persistent effects of acute chlorine exposure and for assessing efficacy of countermeasures for chlorine-induced lung injury.

Lung protective mechanical ventilation strategies in cardiothoracic critical care: a retrospective study.

A body of evidence supports the use of low tidal volumes in ventilated patients without lung pathology to slow progress to acute respiratory distress syndrome (ARDS) due to ventilator associated lung injury. We undertook a retrospective chart review and tested the hypothesis that tidal volume is a predictor of mortality in cardiothoracic (medical and surgical) critical care patients receiving invasive mechanical ventilation. Independent predictors of mortality in our study included: type of surgery, albumin, H+, bilirubin, and fluid balance. In particular, it is important to note that cardiac, thoracic, and transplant surgical patients were associated with lower mortality. However, our study did not sample equally from The Berlin Definition of ARDS severity categories (mild, moderate, and severe hypoxemia). Although our study was not adequately powered to detect a difference in mortality between these groups, it will inform the development of a large prospective cohort study exploring the role of low tidal volume ventilation in cardiothoracic critically ill patients.

Avaliação endoscópica das vias aéreas, do perfil de gases, dos eletrólitos e do equilíbrio ácido-base em equinos submetidos ao treinamento de três tambores

RESUMO O objetivo deste estudo foi avaliar as vias aéreas por endoscopia, o perfil de gases, de eletrólitos e o equilíbrio ácido-base de equinos da raça Quarto de Milha (QM) antes e após o exercício de três tambores. Dezesseis cavalos, divididos em dois grupos de oito animais, treino regular (TR - cinco vezes) e treino esporádico (TE - duas vezes por semana), foram utilizados no experimento. A endoscopia foi realizada antes e 90 min após o exercício. Foram realizadas duas coletas de sangue por punção da artéria facial transversa antes do aquecimento (M0) e imediatamente após o exercício (M1), e as leituras foram realizadas com o I-Stat(r). Foram determinadas PCO2, PO2, SO2, pH, BE, HCO3 e TCO2, Na+, K+, iCa, glicose, Hg e Ht. Foi utilizada ANOVA com medidas repetidas no tempo para comparações dos grupos e dos momentos (P&lt;0,05). A HFL acometeu em grau leve (1-2) os animais de ambos os grupos, com 8/8 (100%) no TR e 5/8 (62,5%) no TE. Observou-se presença de secreção serosa na traqueia em 4/8 (50%) para ambos os grupos. A HPIE acometeu em grau leve (1-2) os animais de ambos os grupos, com 4/8 (50%) no grupo TR e 3/8 (37,5%) no grupo TE. Os animais com grau 2 de HPIE apresentaram leve hipoxemia e hipercapnia pós-exercício. SO2, PCO2, pH, HCO3, BE, K e iCa+ não diferiram estatisticamente (P&gt;0,05) entre os grupos. Os cavalos da raça QM submetidos ao exercício de TT apresentam HPIE e acidose metabólica.

Changes in bispectral index score and cardiorespiratory function under constant rate infusion with alfaxalone in dogs

Changes in the cardiovascular and bispectral index score were evaluated in dogs subjected to constant rate infusion (CRI) with alfaxalone. Fifteen dogs were assigned to three groups of 5. Groups and doses of alfaxalone were as follows: group 1, 3 mg/kg for induction and 6 mg/kg/h for CRI; group 2, 3 mg/kg for induction and 8 mg/kg/h for CRI; and group 3, 3 mg/kg for induction and 10 mg/kg/h for CRI. CRI was maintained for 1 h. Respiratory rates and blood pressures showed minimal changes; however, mild tachycardia and mild hypoxemia occurred, especially in group 3. There were some disparities between bispectral index score, electromyography and pedal withdrawal reflex test when measuring anesthetic depth. Additional premedications and/or analgesic agents would be helpful to avoid adverse effects of alfaxalone and provide improved cardiopulmonary functions.

A new experimental model of acid- and endotoxin-induced acute lung injury in rats.

The majority of the animal models of acute lung injury (ALI) are focused on the acute phase. This limits the studies of the mechanisms involved in later phases and the effects of long-term treatments. Thus the goal of this study was to develop an experimental ALI model of aspiration pneumonia, in which diffuse alveolar damage continues for 72 h. Rats were intratracheally instilled with one dose of HCl (0.1 mol/l) followed by another instillation of one dose of LPS (0, 10, 20, 30, or 40 μg/g body weight) 2 h later, which models aspiration of gastric contents that progresses to secondary lung injury from bacteria or bacterial products. The rats were euthanized at 24, 48, and 72 h after the last instillation. The results showed that HCl and LPS at all doses caused activation of inflammatory responses, increased protein permeability and apoptosis, and induced mild hypoxemia in rat lungs at 24 h postinstillation. However, this lung damage was present at 72 h only in rats receiving HCl and LPS at the doses of 30 and 40 μg/g body wt. Mortality (∼50%) occurred in the first 48 h and only in the rats treated with HCl and LPS at the highest dose (40 μg/g body wt). In conclusion, intratracheal instillation of HCl followed by LPS at the dose of 30 μg/g body wt results in severe diffuse alveolar damage that continues at least 72 h. This rat model of aspiration pneumonia-induced ALI will be useful for testing long-term effects of new therapeutic strategies in ALI.

Prevalence of overlap syndrome in chronic obstructive pulmonary disease patients without sleep apnea symptoms.

The co-existence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) is a common phenomenon referred to as overlap syndrome (OS). In this study, we evaluated the prevalence of OS in mild hypoxemic COPD patients without OSA symptoms and compared characteristics of OS and COPD patients. Forty-five COPD patients (mean FEV1 1671.3 ± 532.0 mL) with mild hypoxemia presenting no sleep apnea symptoms (96% men, mean age 67.7 ± 8.5 years) were involved in this study. Clinical characteristics were recorded, biochemical analysis and polygraphy were performed. Twenty-six patients with a RDI of ≥15 events/h were defined as OS (58%). When OS (n = 26) and COPD without OSA (n = 19) groups were compared, BMI (29.6 ± 6.6 vs 25.6 ± 4.9 kg/m2 ; P = 0.03), TNF-α level (24.8 ± 8.1 vs 3.6 ± 0.8 ng/mL; P = 0.03) and sleep time with SpO2 < 90% (23.9 ± 29.4 vs 9.7 ± 21.9%; P = 0.02) were significantly increased in OS. Univariate analysis showed a correlation between RDI and BMI (P < 0.01), Epworth score (P = 0.050), COPD exacerbation frequency (P = 0.046) and TNF-α (P = 0.048). However, multivariate linear regression analysis revealed a significant correlation only between RDI and BMI (P < 0.01). BMI as a predictor of OSA was examined through ROC curve analysis and the area under curve was 0.691 (P = 0.03). To identify OS patients, BMI > 27.2 kg/m2 had a sensitivity of 73% and specificity of 68%. This findings support that high prevalence (58%) of OS in COPD patients without OSA symptoms is related to BMI. Therefore, sleep study should be considered in especially overweight or obese COPD patients, even in those without sleep apnea symptoms.

Effect of Parachlamydia acanthamoebae on pulmonary function parameters in a bovine respiratory model

The aim of this study was to evaluate pulmonary dysfunction induced by experimental infection with Parachlamydia acanthamoebae in calves. Intrabronchial inoculation with P. acanthamoebae was performed in 31 calves aged 2–3 months old at two different challenge doses of 108 and 1010 inclusion-forming units (IFU) per animal. Control animals received heat inactivated bacteria. The effects on pulmonary gas exchange were determined by arterial blood gas analysis and haemoximetry during the 7 days post inoculation (DPI). For pulmonary function testing (PFT), impulse oscillometry, capnography, and measurement of O2 uptake were undertaken in spontaneously breathing animals 7 and 3 days before inoculation and were repeated until 10 DPI.In the early phase after challenge (1–3 DPI), mild hypoxaemia occurred, which was accompanied by a significant reduction in both tidal and alveolar volumes (each related to bodyweight, BW). In parallel, expiratory flow rate and specific ventilation (i.e. minute ventilation related to O2 uptake) were significantly increased. Minute and alveolar ventilations (each related to metabolic BW) increased significantly due to higher respiratory rates, lasting until 4 and 5 DPI, respectively. Oxygen uptake was slightly reduced during the first 2 days after challenge, but increased significantly during the recovery phase, from 4 to 8 DPI. No deterioration in respiratory mechanics or acid–base balance was observed. Respiratory infection with 1010 IFU P. acanthamoebae per calf induced mild respiratory dysfunction, mainly characterised by hypoxaemia. The study's findings do not indicate severe pathophysiological consequences of P. acanthamoebae infection on pulmonary function in the bovine host.

Etomidate plus propofol versus propofol alone for sedation during gastroscopy: a randomized prospective clinical trial.

Sedation with propofol alone during gastroscopy has many side effects. Etomidate has advantages in terms of circulation and respiration compared to propofol. We hypothesized that etomidate plus propofol during gastroscopy would be more safe and effective than propofol alone. Four hundred (n=400) patients were randomly divided into a propofol group (P group) and a etomidate plus propofol group (EP group). The P group was given the first dose of 1% propofol 1mg/kg before gastroscopy, and the EP group was given 1% propofol 0.5mg/kg plus etomidate 0.1mg/kg. Repeated doses of 10-20mg propofol or 5-10mg propofol plus 1-2mg etomidate were administered to maintain an adequate level of sedation. The sedation depth was maintained by bispectral index value of 40-60. The EP group had a lower incidence of systolic hypotension (13.0 vs. 32.5%; P<0.0001), bradycardia (8.5 vs. 16.5%; P=0.0226), mild hypoxemia (6.5 vs. 18.0%; P=0.0007), and severe hypoxemia (2.5 vs. 10.0%; P=0.0031) compared to the P group. Also, the satisfaction of anesthetist and gastroscopist with EP was higher than that of P group (P<0.0001; P=0.018, respectively). Etomidate plus propofol had few effects on respiration and circulation in patients undergoing gastroscopy and was more safe and effective than propofol alone.

Idiopathic non-specific interstitial pneumonia.

Non-specific interstitial pneumonia (NSIP) is an interstitial lung disease that may be idiopathic or secondary to connective tissue disease, toxins or numerous other causes. Idiopathic NSIP is a rare diagnosis and requires exclusion of these other possible causes. Patients typically present in mid-adulthood with dyspnoea, cough and often constitutional symptoms including fever and fatigue. The disease has a female predominance, and more than 50% of patients have never smoked. Physical exam features mild hypoxaemia and inspiratory rales. Pulmonary function tests demonstrate restriction and a low diffusing capacity for carbon monoxide. High-resolution computed tomography abnormalities include predominantly lower lobe subpleural reticular changes, traction bronchiectasis and ground-glass opacities; honeycombing is rarely seen. An evaluation of the underlying pathology is necessary for a firm diagnosis. Histologically, alveolar and interstitial mononuclear cell inflammation and fibrosis are seen in a temporally uniform pattern with preserved underlying alveolar architecture. NSIP must be differentiated from other parenchymal lung diseases including idiopathic pulmonary fibrosis and hypersensitivity pneumonitis. A thorough exposure history and assessment for underlying connective tissue diseases are highly important, as positive findings in these categories would likely denote a case of secondary NSIP. A multi-disciplinary discussion that includes pulmonologist(s), radiologist(s) and pathologist(s) assists in reaching a consensus diagnosis and improves diagnostic accuracy. Treatment of idiopathic NSIP, although not well proven, is generally instituted in the form of immunosuppression. Prognosis is favourable compared with idiopathic pulmonary fibrosis, although the diagnosis still carries an attributable mortality. Herein we will summarize the clinical characteristics and management of idiopathic NSIP.

More severe hypoxemia is associated with better subjective sleep quality in obstructive sleep apnea.

BackgroundPerceived sleep quality may play an important role in diagnosis and therapy for obstructive sleep apnea (OSA). However, few studies have assessed factors that are associated with perceived sleep quality in OSA patients. Hypoxemia depresses the central nervous system and attenuates the perceived respiratory load in asthmatic patients. This study aimed to investigate the factors related to perceived sleep quality, focusing on the role of hypoxemia.MethodsPolysomnography studies of 156 OSA patients were reviewed. Traditional polysomnographic parameters, including parameters of oxy-hemoglobin saturation (SpO2), were calculated, and the sleep questionnaire and scales were used. Considering the possible pitfalls of absolute values of SpO2 and individualized responses to hypoxemia, the amplitude of desaturation was further computed as “median SpO2 minus lowest 5 % SpO2 “and “highest 5 % SpO2 minus median 5 % SpO2”. Correlations between these parameters and perceived sleep quality, represented as the Pittsburgh sleep quality index (PSQI), were performed. Multiple linear regression analysis was also conducted to investigate the factors associated with the PSQI.ResultsAlthough the PSQI was not correlated with the apnea-hypopnea index (r = −0.113, p = 0.162) and oxygen desaturation index (r = −0.085, p = 0.291), the PSQI was negatively correlated with “median SpO2 minus lowest 5 % SpO2” (r = −0.161, p = 0.045). After adjusting for age, total sleep time, the periodic limb movements index, tendency of depression, and the lowest 5 % SpO2, the “median SpO2 minus lowest SpO2” was still a significant predictor for a lower PSQI (β = −0.357, p = 0.015).ConclusionsMore severe hypoxemia is associated with better perceived sleep quality among OSA patients. This paradox may be associated with hypoxemia-related impairment of perception. The effect of hypoxemia did not appear to be significant in relatively mild hypoxemia but become significant in severe hypoxemia.” Median SpO2 minus lowest 5 % SpO2” may also be a better predictor of perceived sleep quality than the apnea-hypopnea index because of the disproportionate effects of hypoxemia. Additionally, further studies are necessary to confirm the role of hypoxemia on perceived sleep quality and identify the possible threshold of hypoxemia in OSA patients.

Assessment of acute lung injury/acute respiratory distress syndrome using B-type brain natriuretic peptide.

To investigate the clinical value of B-type natriuretic peptide (BNP) in the assessment of severity and prognosis in acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Plasma BNP level, arterial blood gases, serum C-reactive protein level, alveolar-arterial oxygen tension difference and oxygenation index were measured in patients with and without ALI/ARDS within 24 h of admission to an intensive care unit. Patients with ALI/ARDS were divided into mild, moderate or severe groups according to the degree of hypoxaemia. Survival >28 days was recorded. A total of 59 patients with ALI/ARDS and 14 patients without ALI/ARDS were included in the study. Of the patients with ALI/ARDS, 18 had mild hypoxaemia, 20 had moderate hypoxaemia and 21 had severe hypoxaemia. The mean ± SD BNP level was significantly higher in all three ALI/ARDS groups (92.41 ± 28.19 pg/ml, 170.64 ± 57.34 pg/ml and 239.06 ± 59.62 pg/ml, respectively, in the mild, moderate and severe groups) than in the non-ALI/ARDS group (47.27 ± 19.63 pg/ml); the increase in BNP level with increasing severity was also statistically significant. When divided according to outcome, the BNP level in the death group (267.07 ± 45.06 pg/ml) was significantly higher than in the survival group (128.99 ± 45.42 pg/ml). The BNP level may be of value in evaluating severity and prognosis in patients with ALI/ARDS.

The role of airflow for the relief of chronic refractory breathlessness.

Chronic refractory breathlessness is a major cause of suffering to people with advanced stage cardiorespiratory and some neurodegenerative diseases. It is a frightening, distressing and disabling symptom that imposes significant burdens on family members. Evidence is mounting for the role of facial or nasal airflow for the relief of chronic refractory breathlessness in those patients with mild hypoxaemia or normoxaemia. Airflow can be delivered from a cylinder of compressed medical air via face mask or nasal cannulae or a hand-held fan. The hand-held fan offers patients a simple, low-cost, self-management strategy that is not associated with any known risks. Therefore, it is timely and relevant to review the research available for the efficacy and appropriateness of facial or nasal airflow. There is sufficient review evidence available to suggest that airflow from the hand-held fan or medical air can provide clinically relevant and discernible relief of chronic refractory breathlessness at rest in patients with advanced diseases. The hand-held fan should be considered as one of the first interventions to try in management plans for patients who present with mild hypoxaemia or normoxaemia and chronic refractory breathlessness at rest or on minimal exertion. Emerging evidence indicates that airflow from the hand-held fan may also have an important role with exertion-induced breathlessness, decreasing distress and speeding recovery time after exercise, thereby helping patients self-manage their symptoms during everyday general activity and plan for crises of breathlessness, secure in the knowledge that they have a tangible, easily portable device to try in any circumstances.

Adjunctive corticosteroids for Pneumocystis jiroveci pneumonia in patients with HIV infection.

Pneumocystis jiroveci pneumonia (PCP) remains the most common opportunistic infection in patients infected with the human immunodeficiency virus (HIV). Among patients with HIV infection and PCP the mortality rate is 10% to 20% during the initial infection and this increases substantially with the need for mechanical ventilation. It has been suggested that corticosteroids adjunctive to standard treatment for PCP could prevent the need for mechanical ventilation and decrease mortality in these patients. To assess the effects of adjunctive corticosteroids on overall mortality and the need for mechanical ventilation in HIV-infected patients with PCP and substantial hypoxaemia (arterial oxygen partial pressure < 70 mmHg or alveolar-arterial gradient > 35 mmHg on room air). For the original review we searched The Cochrane Library (2004, Issue 4), MEDLINE (January 1980 to December 2004) and EMBASE (January 1985 to December 2004) without language restrictions. We further reviewed the reference lists from previously published overviews, searched UptoDate version 2005 and Clinical Evidence Concise (Issue 12, 2004), contacted experts in the field and searched the reference lists of identified publications for citations of additional relevant articles.In this update of our review, we searched the above-mentioned databases in September 2010 and April 2014 for trials published since our original review. We also searched for ongoing trials in ClinicalTrials.gov and the World Health Organization International Clinical Trial Registry Platform (ICTRP). We searched for conference abstracts via AEGIS. Randomised controlled trials that compared corticosteroids to placebo or usual care in HIV-infected patients with PCP in addition to baseline treatment with trimethoprim-sulfamethoxazole, pentamidine or dapsone-trimethoprim, and reported mortality data. We excluded trials in patients with no or mild hypoxaemia (arterial oxygen partial pressure > 70 mmHg or an alveolar-arterial gradient < 35 mmHg on room air) and trials with a follow-up of less than 30 days. Two teams of review authors independently evaluated the methodology and extracted data from each primary study. We pooled treatment effects across studies and calculated a weighted average risk ratio of overall mortality in the treatment and control groups using a random-effects model.In this update of our review, we used the GRADE methodology to assess evidence quality. Of 2029 screened records, we included seven studies in the review and six in the meta-analysis. Risk of bias varied: the randomisation and allocation process was often not clearly described, five of seven studies were double-blind and there was almost no missing data. The quality of the evidence for mortality was high. Risk ratios for overall mortality for adjunctive corticosteroids were 0.56 (95% confidence interval (CI) 0.32 to 0.98) at one month and 0.59 (95% CI 0.41 to 0.85) at three to four months of follow-up. In adults, to prevent one death, numbers needed to treat are nine patients in a setting without highly active antiretroviral therapy (HAART) available, and 23 patients with HAART available. The three largest trials provided moderate quality data on the need for mechanical ventilation, with a risk ratio of 0.38 (95% CI 0.20 to 0.73) in favour of adjunctive corticosteroids. One study was conducted in infants, suggesting a risk ratio for death in hospital of 0.81 (95% CI 0.51 to 1.29; moderate quality evidence). The number and size of trials investigating adjunctive corticosteroids for HIV-infected patients with PCP is small, but the evidence from this review suggests a beneficial effect for adult patients with substantial hypoxaemia. There is insufficient evidence on the effect of adjunctive corticosteroids on survival in infants.

Fitness to fly in patients with lung disease.

Patients with chronic lung disease may have mild hypoxemia at sea level. Some of these cases may go unrecognized, and even among those who are known to be hypoxemic, some do not use supplemental oxygen. During air travel in a hypobaric hypoxic environment, compensatory pulmonary mechanisms may be inadequate in patients with lung disease despite normal sea-level oxygen requirements. In addition, compensatory cardiovascular mechanisms may be less effective in some patients who are unable to increase cardiac output. Air travel also presents an increased risk of venous thromboembolism. Patients with cystic lung disease may also be at increased risk of pneumothorax. Although overall this risk appears to be relatively low, should a pneumothorax occur, it could present a significant challenge to the patient with chronic lung disease, particularly if hypoxemia is already present. As such, a thorough assessment of patients with chronic lung disease and cardiac disease who are contemplating air travel should be performed. The duration of the planned flight, the anticipated levels of activity, comorbid illnesses, and the presence of risk factors for venous thromboembolism are important considerations. Hypobaric hypoxic challenge testing reproduces an environment most similar to that encountered during actual air travel; however, it is not widely available. Assessment for hypoxia is otherwise best performed using a normobaric hypoxic challenge test. Patients in need of supplemental oxygen need to contact the airline and request this accommodation during flight. They should also be advised on arranging portable oxygen concentrators before air travel, and a discussion of the potential risks of travel should take place.

Oxygen therapy for COPD.

Chronic obstructive pulmonary disease (COPD) is a leading cause of disability and death globally, characterised by progressive breathlessness, loss of function and, in its later stages, chronic hypoxaemia. Long-term continuous oxygen therapy increases life expectancy in patients with severe resting hypoxaemia. However, there are few data to support the use of oxygen in patients with only mild hypoxaemia and more research is required to determine any benefits of oxygen supplementation in COPD in such individuals.

COPD Assessment Test (CAT) score as a predictor of major depression among subjects with chronic obstructive pulmonary disease and mild hypoxemia: a case-control study.

BackgroundDepression is a common comorbidity among patients with Chronic Obstructive Pulmonary Disease (COPD) and has a significant impact on the course of the disease. The aim of this study is to determine association between COPD Assessment Test (CAT) and major depression among clinically stable out-patient COPD subjects with mild hypoxemia.MethodsCase–control study. Cases were 30 patients with major depression and controls were 30 patients without depression. Major depression was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders criteria by a psychiatric evaluation. All possible predictive variables were included in a multivariate logistic regression model to assess the association between major depression and each independent variable, while controlling for the sleep parameters.ResultsCAT score >20 was associated with major depression (OR 7.88; 95% CI 1.96 - 31.7; p = 0.004).ConclusionCAT score >20 was associated with major depression, suggesting CAT as a predictor variable of major depression among COPD patients with mild hypoxemia, and indicating that an additional specific evaluation for the presence of major depression should be done.

Association between Arterial Stiffness and Acute Exacerbations in Patients with Chronic Obstructive Pulmonary Disease

Background: Arterial stiffness (AS) indicates decreased arterial elasticity and damage in the vessel wall. It is an independent determining factor for cardiovascular (CV) events. Acute exacerbation in COPD (AECOPD ) can result in a major systemic effect due to hypoxemia and systemic inflammation. Objective: We aimed to investigate the effects of AECOPD on arterial stiffness (AS) in patients admitted to our hospital. Method: Study population was consisted of 25 patients who had been admitted to our hospital between May and December 2011 with AECOPD and 21 healthy controls. Arterial stiffness and blood pressure of subjects were determined using radial artery applanation tonometry and sphygmomanometry. Results: The average AS values were 1498.00±699.35 dyne.sec.cm-5 in patients with mild hypoxemia, 2095.09±883.31 dyne.sec.cm-5 in those with moderate hypoxemia, and 2077.66±99.15 dyne.sec.cm-5 in those with severe hypoxemia. There was a statistically significant difference in values of AS, compared between mild hypoxemia (PaO2≥60 mm Hg) and moderate and severe hypoxemia (PaO2<60 mm Hg) (p=0.047). Arterial stiffness was significantly higher, while the large artery elasticity index (LAEI) and small artery elasticity index (SAEI) were lower in the patient group as compared to the control group (p=0.002, p=0.043, and p=0.036, respectively). Conclusion: LAEI and SAEI were lower, while AS was higher in COPD patients as compared to healthy individuals. Severe exacerbations with hypoxemia might increase CV risks. Measuring arterial stiffness might be an effective method in predicting cardiovascular events and risks in COPD patients.

A Functional Univentricle: Large Ventricular Septal Defect, Atrioventricular Discordance, Malposition of the Great Arteries, Pulmonary Stenosis, and Major Aorto Pulmonary Collaterals

AbstractWe report a case of a 25 year-old male with a functionally univentricular heart. He underwent consult for clearance prior to employment and has been asymptomatic since childhood with good functional capacity, his 6 minute walk test was normal at 300 meters. Pertinent physical findings were a right ventricular heave, a grade 3/6 systolic murmur over the 2nd-3rd intercostal spaces left parasternal border, a continuous murmur over the interscapular area and cyanosis of the nailbeds. Laboratory exams showed mild erythrocytosis and hypoxemia. Transthoracic and transesophageal echocardiographic findings showed a large ventricular septal defect (apical intraventricular septum remnant), atrioventricular discordance, malposition of the great arteries and severe pulmonary stenosis. Major aorto-pulmonary collaterals were demonstrated on hemodynamics study. Patient is stable and living a normal life but advised to avoid moderate to heavy strenuous activities. He is on a regular follow – up at our out patient clinic and there are no planned immediate surgical interventions at present.