[Application of computational fluid dynamics in the evaluation of left ventricular function in cardiomyopathies and coronary disease].

Computational fluid dynamics (CFD) is an emerging technology applied in the field of cardiovascular medicine, which can obtain hemodynamic data by simulating the blood flow in the patient's heart for cardiac function assessment and disease diagnosis. Left ventricular function plays a key role in the occurrence and development of cardiomyopathies and coronary disease. CFD can reconstruct the left ventricular anatomic structures of patients to clarify pathophysiologic mechanisms and analyze hemodynamic parameters to evaluate left ventricular function, verify surgical efficacy, and guide surgical strategy, which has a positive effect on achieving early diagnosis and reducing mortality from cardiomyopathies and coronary disease. At present, there are still technical limitations in the large-scale clinical application of CFD, and various solutions are being developed and tested, and further improvement and refinement are needed.

[Clinical features and related factors of invasive pulmonary aspergillosis in patients with acute exacerbation of chronic obstructive pulmonary disease].

Objective: To study the clinical features and related factors of invasive pulmonary aspergillosis (IPA) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods: This retrospective study enrolled patients hospitalized for AECOPD in ten tertiary hospitals of China from September 2017 to July 2021. AECOPD patients with IPA were included as case group, AECOPD patients without IPA were randomly selected as control group from the same hospitals and same hospitalization period as the patients with IPA using the random function in the software of Microsoft Excel 2003, at a ratio of 2∶1. The clinical characteristics, treatment and outcome were compared between the two groups. Binary logistic regression model was used to analyze the factors associated with IPA in AECOPD patients. Results: A total of 14 007 inpatients with AECOPD were included in this study, and 300 patients were confirmed to have IPA, with an incidence rate of 2.14%. According to the above matching method, 600 AECOPD patients without aspergillus infection were enrolled as the control group. The age of the case group and the control group were (72.5±9.7) and (73.5±10.3) years old, with 78.0%(n=234) male and 76.8%(n=461) male, respectively. There were no significant differences in age and gender composition between the two groups (all P>0.05). The prognosis of case group was significantly worse than that of the control group, with longer hospital stay [M(Q1,Q3)], [14 (10-20) d vs 11 (8-15) d, P<0.001], higher ICU admission rate [16.3% (49 case) vs 10.0% (60 case), P=0.006], higher in-hospital mortality [4.0% (12 cases) vs 1.3% (8 cases), P=0.011], and higher hospitalization costs (28 000 ¥ vs 13 700 ¥, P<0.001). The smoking index of the case group and proportions of patients with diabetes mellitus, chronic pulmonary heart disease in the case group were significantly higher than those in control group (all P<0.05). In terms of clinical features, the proportions of patients with cough, expectoration, purulent sputum, hemoptysis and fever in the case group were higher than those in the control group, the serum albumin was significantly lower than that in the control group, and the proportions of patients with bronchiectasis and pulmonary bullae on imaging were significantly higher than those in the control group (all P<0.05). Diabetes (OR=1.559, 95%CI: 1.084-2.243), chronic pulmonary heart disease (OR=1.476, 95%CI: 1.075-2.028), bronchiectasis (OR=1.506, 95%CI: 1.092-2.078), pulmonary bullae (OR=1.988, 95%CI: 1.475-2.678) and serum albumin<35 g/L (OR=1.786, 95%CI: 1.325-2.406) were the related factors of IPA in patients with AECOPD. Conclusions: The incidence of IPA in AECOPD patients is relatively high and the prognosis of these patients is worse. Diabetes, chronic pulmonary heart disease, bronchiectasis, pulmonary bulla, hypoproteinemia are the related factors of IPA in patients with AECOPD.

[The clinical characteristics of nuclear dense fine speckled pattern in 95 289 patients].

To investigate the distribution and clinical significance of nuclear dense fine speckled (DFS) pattern in various diseases. A total of 95 289 patients who received DFS tests at Peking Union Medical College Hospital from January 2019 to December 2020 were included in this study. The results of indirect immunofluorescence assay (IIF) for detection of antinuclear antibody (ANA) were evaluated. The positive rates of ANA and DFS were 39.60% (37 733/95 289) and 1.19% (1 139/95 289) respectively. The positive rate of DFS in ANA-positive patients was 3.02% (1 139/37 733). DFS and ANA positivity were significantly different among different age groups rather than gender. The positivity rate of DFS reached the peak (55.57%, 633/1 139) in young patients between 21-40 years, while positive ANA with negative DFS was mainly observed in patients between 41-60 years (37.26%, 13 636/36 594). Additionally, single ANA-positivity were mainly detected in rheumatology department (59.23%, 18 402/31 066), whereas positive DFS was more common in obstetrics and gynecology department (3.08%, 49/1 593). There were 82.88% (944/1 139) patients with positive DFS diagnosed with non-autoimmune disease (non-AID), and 19.49%(222/1 139) with dermatosis. Positive DFS with higher titer (≥1∶320) was detected more frequently in autoimmune disease (AID) patients (5.13%, 10/195) than in non-AID patients (1.69%, 16/944) (P<0.05). The DFS pattern is rare in ANA positive patients, which is mainly observed in women between 21-49 years. High titer of DFS is prevalent in AID patients, but positive DFS is detected more in non-AID patients, especially those with dermatosis.

[Evaluation of vestibular-evoked myogenic potential for functional integrity of the brain stem in Kennedy's disease].

Objective: To investigate whether vestibular-evoked myogenic potentials(VEMPs) can be used to assess brainstem involvement in patients with Kennedy's disease (KD). Method: This was a case-control study.Twenty consecutive patients with genetically confirmed KD and 20 age-and sex-matched healthy subjects were enrolled from November 2018 to September 2020.All subjects were tested for three types of VEMPs, including cervical VEMP (c-VEMP) recorded by the sternocleidomastoid muscle (parameter:p13, n23), masseter VEMP (m-VEMP) recorded by the masseter muscle(parameter: p11), and ocular VEMP (o-VEMP) recorded by the inferior oblique muscle (parameter n10, p15).The latency of each wave, interside peak latency and interpeak latency of c-VEMP, the corrected amplitude and amplitude asymmetry ratio were recorded. Bilateral sternocleidomastoid muscle (SCMM) electromyography (EMG) was performed. The spinal cord and bulbous muscular atrophy functional rating scale (SBMAFRS) was used for assessment. Results: The mean p13 latency of c-VEMP was (15.5±1.4)ms, which was longer than that of the control group[(13.3±0.9)ms](P<0.05); the mean n23 latency was(25.5±1.4)ms, which was also longer than that of the control group[(22.5±1.0)ms] (P<0.05); the difference of bilateral p13[(2.3±0.6)ms] was significantly higher than that of the control group(P<0.05). The abnormal rates of c-, m-, o-VEMP in KD patients were 75%(15/20), 30%(6/20) and 20%(4/20), respectively. There was a significant positive correlation between c-VEMP latency and course of disease in KD patients(left: r=0.715, 0.695, right: r= 0.708, 0.715, both P<0.05). However, c-VEMP latency was negatively correlated with SBMAFRS score (left: r=-0.701, -0.694, right: r=-0.644, -0.685, both P<0.05). Abnormal rates of SCMM EMG in KD group were as follows: 15%(3/20)of patients showed spontaneous potential in resting state and 45% (9/20) of patients exhibited simple recruitment. Conclusions: The c-VEMP latency is a sensitive tool for detecting lower brainstem involvement in patients with KD, and the degree of damage increases with prolongation of disease course. The o-and m-VEMP abnormalities indicate that some KD patients develop upper brainstem damage.

[Risk factors associated with in-hospital mortality in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease: a multicenter retrospective study].

Objective: To investigate the risk factors associated with in-hospital mortality in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Methods: A total of 6 668 patients hospitalized for AECOPD in seven tertiary hospitals from September 2017 to January 2021 were consecutively included, and clinical data related to medical history, laboratory tests, treatment and prognosis were collected, and patients were divided into death group and survival group according to whether they died during hospitalization. After univariate analysis, multivariate logistic regression analysis was then performed to explore the independent risk factors related to in-hospital mortality. Results: Among 6 668 patients hospitalized for AECOPD, 128 patients experienced in-hospital death, with a mortality rate of 1.9%. The mean age of the death group was (81±9) years, which was significantly older than that of the survival group ((72±11) years P<0.001). The proportion of patients in the AECOPD in-hospital death group with a combination of prolonged bed rest, hypertension, myocardial infarction within 3 months, cardiac insufficiency, chronic pulmonary heart disease, pneumonia, type 2 diabetes, venous thromboembolism (VTE), and chronic renal insufficiency was also significantly higher than in the survival group (all P<0.05) The median length of stay in the in-hospital death group was 18 d, which was significantly longer than that in the survival group (9 d, P<0.001), and the proportion of patients admitted to the ICU, receiving invasive mechanical ventilation and non-invasive mechanical ventilation was also significantly higher than that in the survival group (all P<0.05). The white blood cell count, glutamic transaminase, blood creatinine, calcitoninogen, C-reactive protein, D-dimer, N-terminal B-type natriuretic and Pseudomonas aeruginosa infection rates were significantly higher than those in the survival group (all P<0.05). Multifactorial analysis showed that age>80 years (OR=3.82, 95%CI 2.36 to 6.18, P<0.001), prolonged bed rest (OR=2.95, 95%CI: 1.79 to 4.86, P<0.001), chronic pulmonary heart disease (OR=1.85, 95%CI: 1.14 to 3.00, P=0.012), and pneumonia (OR=2.75, 95%CI: 1.65 to 4.60, P<0.001), invasive mechanical ventilation (OR=7.33, 95%CI: 4.40 to 12.21, P<0.001), noninvasive mechanical ventilation (OR=3.73, 95%CI: 2.30 to 6.04, P<0.001), anemia (OR=2.03. 95%CI: 1.21 to 3.42, P=0.008), and calcitoninogen>0.5 ng/ml (OR=2.38, 95%CI: 1.41 to 4.02, P=0.001) were independent risk factors for in-hospital mortality in patients with AECOPD. Conclusion: Advanced age (>80 years), prolonged bed rest, chronic pulmonary heart disease, pneumonia, invasive mechanical ventilation, noninvasive mechanical ventilation, anemia, and calcitoninogen>0.5 ng/ml were independent risk factors for in-hospital mortality in patients hospitalized with AECOPD.

Fast and deterministic switching of a vortex core induced by an out-of-plane current in notch disks.

The magnetic vortex, as one of the most interesting magnetic solitons, has attracted great interest over the past two decades. A fast and reliable method to switch vortex polarity and chirality is one of the key issues for various applications. Based on micromagnetic simulation, here we report a fast, low energy cost and deterministic switching of a vortex core, by the designing of a notch structure in disks and the use of out-of-plane current geometry. We demonstrate that with such a design, the multiple switching problems found in notch disk systems can be avoided. Furthermore, the switching time can be reduced by more than 50% compared with disks without notches.

[Efficacy of simple continuous positive airway pressure on patients with obstructive sleep apnea].

Objective: To investigate the efficacy of simple device of continuous positive airway pressure (CPAP) in the treatment of obstructive sleep apnea (OSA). Methods: A double-blind study was performed on 53 OSA patients who received overnight simple CPAP and traditional CPAP in a random order during polysomnography. Pressure for CPAP treatment was manual titrated. The sleep apnea hypopnea index (AHI), arousal index (ArI), Oxygen desaturation Index (ODI), sleep structure and the preference for CPAP devices of the patients were observed. Results: AHI, ArI, ODI decreased significantly from 35.7 (18.1, 58.8)/h, (29.4±18.6)/h, 22.0 (13.9, 47.3)/h before treatment to 1.7 (0.7, 4.4)/h, (11.5±5.1) /h and 1.3 (0.4, 3.6)/h after treatment with simple CPAP, respectively (all P<0.05). There was no statistically significant difference in residual AHI [1.7 (0.7, 4.4)/h vs 1.9 (0.8, 4.3)/h], ArI [(11.5±5.1)/h vs (10.5±4.4)/h] and ODI [1.3 (0.4, 3.6)/h vs 1.3 (0.5, 4.2)/h] between treatment with simple CPAP and traditional CPAP (all P>0.05). The amount of time spent on deep sleep (stage Ⅲ) and rapid eye movement (REM) increased significantly from (6.2+ 6.6)% and (16.3+ 7.0)% before treatment to (11.7±8.5)% and (20.7±5.1)% during treatment with simple CPAP and (11.4±8.6)% and (20.9±5.0)% with traditional CPAP, respectively. The patients had no clear preference for two CPAP devices. Conclusion: Traditional CPAP can be replaced by the simple CPAP to treat patients with OSA.

Screening for sleep-disordered breathing in neuromuscular disease using a questionnaire for symptoms associated with diaphragm paralysis.

Patients with neuromuscular disease (NMD) are at risk of developing sleep-disordered breathing (SDB) following respiratory muscle involvement. We hypothesised that a questionnaire based on clinical symptoms and signs of diaphragm weakness can be used to screen for SDB in such patients. We developed a self-administered multiple choice questionnaire containing five questions (Sleep-Disordered Breathing in Neuromuscular Disease Questionnaire (SiNQ)-5), scoring 0-10 points. 125 patients were enrolled: 32 with respiratory muscle weakness, 35 subjects with normal respiratory muscle strength and 58 patients with obstructive sleep apnoea (OSA). All subjects underwent full polysomnography. NMD patients with involvement of the respiratory muscles scored mean ± sd 6.8 ± 2.3 out of 10 points, significantly higher than both OSA patients 2.5 ± 2.3 and normal subjects 1.0 ± 2.0 (p < 0.001). A score of five or more points in the SiNQ-5 had a sensitivity of 86.2%, specificity of 88.5%, positive predictive value of 69.4% and a negative predictive value of 95.5% to identify NMD with combined SDB. A short self-administered questionnaire, the SiNQ-5, based on clinical symptoms can reliably screen for SDB in patients with diaphragm weakness. However, comorbidities, such as heart failure, that have symptoms influenced by posture could alter diagnostic accuracy.

Neural respiratory drive in patients with COPD during exercise tests.

BACKGROUND: It is unknown whether neural drive is comparable in constant rate and incremental exercise tests. Few data have previously been available to address this question because of the lack of reliable methods to assess neural respiratory drive in patients with chronic obstructive pulmonary disease (COPD). OBJECTIVES: The aims of this study are to determine whether neural respiratory drive during constant rate exercise differs from that during incremental exercise and to determine whether neural respiratory drive was maximal at the end of exhaustive exercise tests. METHODS: We studied sixteen patients with moderate-severe COPD (mean ± SD FEV(1) 29 ± 10%). Both diaphragmatic electro-myogram (EMG) and transdiaphragmatic pressure were recorded with a combined multipair electrode balloon catheter during incremental and constant (80% of maximal oxygen consumption derived from a prior incremental exercise test) treadmill exercise. Minute ventilation and oxygen uptake were also measured. RESULTS: Root mean square (RMS) of the diaphragmatic EMG increased gradually without a plateau during incremental exercise, whereas the RMS increased initially and reached a plateau during constant work rate exercise. The RMS of the diaphragmatic EMG at the end of exercise was similar for both incremental and constant work rate exercise (176 ± 42 µV vs. 184 ± 39 µV); these values were 70 and 73% of maximal values recorded over the study. CONCLUSIONS: The pattern of increase in neural respiratory drive during incremental exercise is different to that observed during constant work rate exercise, but both exercise protocols are terminated when the patients achieve a similar but submaximal drive.

[Application of a standard communication system-based continuous home remote visit mode in the management of visits to severely burned patients in the post-pandemic era of coronavirus disease 2019].

Objective: To observe the application effects of a standard communication system-based continuous home remote visit mode in the management of visits to severely burned patients in the post-pandemic era of coronavirus disease 2019 (hereinafter referred to as post-pandemic era). Methods: A retrospective cohort study was conducted. A total of 69 severely burned patients who met the inclusion criteria and were admitted to the First Affiliated Hospital of Army Medical University (the Third Military Medical University) from February to December, 2020 and their 69 family members were recruited into this study. According to the difference of visit model, 33 severely burned patients who were admitted into burn intensive care unit (BICU) from February to June, 2020 and received completely restricted visits according to the requirements for epidemic prevention and control and their corresponding 33 family members were included into conventional visit group; 36 severely burned patients who were admitted into BICU from July to December, 2020 and received the standard communication system-based continuous home remote visits and their 36 corresponding family members were recruited into remote visit group. The family members in conventional visit group could only communicate with the primary nurses by telephone, while the patients and family members in remote visit group could communicate with the primary nurses, responsible doctors, rehabilitation therapists, and nutrition therapists through WeChat video call. The survey results of general information questionnaire and Hamilton Anxiety Scale (HAMA) scores of two groups of patients and their family members at BICU admission of patients, HAMA scores of the two groups of patients and their family members in the second week of BICU admission and at discharge from BICU of patients, the scores of the Visiting Effect Evaluation Scale of the two groups of patients and their family members and the scores of Chinese version of Critical Care Family Satisfaction Survey (C-CCFSS) of the two groups of family members at discharge from BICU, and the scores of Satisfaction Survey and Evaluation Scale During Hospitalization of patients within the first week after the discharge of patients from BICU were compared. Data were statistically analyzed with chi-square test, Fisher's exact probability test, and Mann-Whitney U test. Results: In remote visit group, there were 29 males and 7 females in patients, aged 48 (34, 53) years, and 15 males and 21 females in family members, aged 45 (30, 48) years. In conventional visit group, there were 24 males and 9 females in patients, aged 49 (38, 54) years, and 9 males and 24 females in family members, aged 44 (35, 48) years. At BICU admission of patients, the HAMA scores of the two groups of patients and family members were both similar (P>0.05). The total HAMA scores of patients and family members in remote visit group were significantly lower than those in conventional visit group in the second week when the patients were admitted to BICU (Z=-3.195, -3.018, P<0.01) and discharged from BICU (Z=-2.118, -2.380, P<0.05). At discharge from BICU of patients, the scores of each dimension in Visiting Effect Evaluation Scale of the patients in the two groups were similar (P>0.05); while scores of 3 dimensions including patient safety information, diagnosis and treatment quality information, and psychological support information in Visiting Effect Evaluation Scale of family members in remote visit group were significantly higher than those in conventional visit group (Z=-2.372, -2.209, -2.174, P<0.05), and only the scores of visit perception of family members were close to those in conventional visit group (P>0.05). At discharge from BICU of patients, the C-CCFSS scores of the family members in remote visit group was 99 (98, 108), which were significantly higher than 98 (97, 100) in conventional visit group (Z=-2.545, P<0.05). Within the first week after the discharge of patients from BICU, the scores of Satisfaction Survey and Evaluation Scale During Hospitalization of patients in remote visit group were 99 (98, 100), which were significantly higher than 96 (94, 98) in conventional visit group (Z=-5.213, P<0.01). Conclusions: In the management of visits to severely burned patients in the post-pandemic era, application of the standard communication system-based continuous home remote visit mode can improve the visit effect and satisfaction, and effectively alleviate the anxiety of patients and their family members.

[Clinical application effect of modified nasopharyngeal swab sampling for 2019 novel coronavirus nucleic acid detection].

Objective: To study the clinical application effect of modified nasopharyngeal swab sampling for 2019 novel coronavirus nucleic acid detection. Methods: This study covered the period from January 14 to March 1, 2020.The supine position method and the protective face screen were used to collect nasopharyngeal swabs from February 24 onwards, before which, the nasopharyngeal swabs were collected by sitting position method. All the patients who were diagnosed with suspected/confirmed 2019 novel coronavirus infection were admitted from February 19 with the nasopharyngeal swabs collected outside the hospital before admission. (1) Thirty-four swabbing operators meeting the inclusion criteria of the study were recruited in this retrospective cohort study. They were grouped according to the collection method of nasopharyngeal swabs. Sixteen operators of Wuhan Taikang Tongji Hospital who applied the supine position method and the protective face screen were included in supine position method+ protective face screen group (15 males and 1 female, aged 34-49 years); 18 operators (12 from the First Affiliated Hospital of Army Medical University (the Third Military Medical University), 1 from Wuhan Jiangxia Mobile Cabin Hospital, 5 from the East District of People's Hospital of Wuhan University) who applied the traditional sitting position method were included in sitting position method group (2 males and 16 females, aged 25-49 years). In supine position method+ protective face screen group, when collecting sample, the patient lay flat and wore a special protective face screen for nasopharyngeal swab sampling, with neck slightly extending and face turning to the opposite side of the operator about 10°. The self-designed questionnaire was used to investigate the cooperation, the incidence of nausea, coughing, sneezing, and struggling of patients evaluated by the operators, the operation time for a single swab sample, the fear of operation and the perceived exposure risk of operators in the two groups. (2) Sixty-five patients (22 males and 43 females, aged 25-91 years) admitted to Wuhan Taikang Tongji Hospital who successively received the sitting position method and supine position method+ protective face screen for nasopharyngeal swabs sampling and with complete nucleic acid detection results were included. The positive rates of nucleic acid detection by the two sampling methods of nasopharyngeal swabs of the patients were statistically analyzed. (3) Forty-one patients who could express their feelings accurately were selected out of those 65 patients (12 males and 29 females, aged 27-83 years). The comfort of patients in the process of sampling by the two methods was investigated. (4) Thirty-four patients (10 males and 24 females, aged 25-83 years) with two or more consecutive negative results of nucleic acid detection of nasopharyngeal swabs by sitting position method were selected from the above 65 patients. The positive rate of nucleic acid detection of nasopharyngeal swab of patients by supine position method+ protective face screen, i. e. negative to positive rate was statistically analyzed. Data were statistically analyzed with t test, Wilcoxon signed rank test, and chi-square test. Results: (1) Compared with those of sitting position method group, the cooperation score of patients evaluated by the operators in supine position method+ protective face screen group was significantly higher (Z=-4.928, P<0.01), the incidence of nausea, choking cough, sneezing, and struggling of patients evaluated by the operators, and the fear of operation score and the perceived exposure risk score of operators in supine position method+ protective face screen group were significantly lower (Z=-5.071, -5.046, -4.095, -4.397, -4.174, -5.049, P<0.01), and the operation time for a single swab sample in supine position method+ protective face screen group was significantly longer (t=223.17, P<0.01). (2) The positive rate of nucleic acid detection of nasopharyngeal swabs by supine position method+ protective face screen was 60.00% (39/65), which was obviously higher than 41.54% (27/65) by sitting position method (χ(2)=4.432, P<0.05). (3) The comfort score of the 41 patients during nasopharyngeal swabs sampling by supine position method+ protective face screen was significantly higher than that by sitting position method (Z=-5.319, P<0.01). (4) Of the 34 patients with two or more consecutive negative results of nucleic acid detection of nasopharyngeal swabs by sitting position method, the rate of negative to positive of nucleic acid detection was 26.47% (9/34) after sampling by supine position method+ protective face screen. Conclusions: Compared with the traditional sitting position method, detection of 2019 novel coronavirus nucleic acids of nasopharyngeal swabs collected by supine method combined with protective face screen is worth promoting, because of its better comfort of patients, low exposure risk for operators, in addition to reducing in the false negative result to some extent, which may help reduce false recurrence of discharged patients.

Neural respiratory drive in healthy subjects and in COPD.

The aim of the present study was to use the diaphragm electromyogram (EMG(di)) to compare levels of neural respiratory drive (NRD) in a cohort of healthy subjects and chronic obstructive pulmonary disease (COPD) patients, and to investigate the relationship between NRD and pulmonary function in COPD. EMG(di) was recorded at rest and normalised to peak EMG(di) recorded during maximum inspiratory manoeuvres (EMG(di) % max) in 100 healthy subjects and 30 patients with COPD, using a multipair oesophageal electrode. EMG(di) was normalised to the amplitude of the diaphragm compound muscle action potential (CMAP(di,MS)) in 64 healthy subjects. The mean+/-sd EMG(di) % max was 9.0+/-3.4% in healthy subjects and 27.9+/-9.9% in COPD patients, and correlated with percentage predicted forced expiratory volume in one second, vital capacity and inspiratory capacity in patients. EMG(di) % max was higher in healthy subjects aged 51-80 yrs than in those aged 18-50 yrs (11.4+/-3.4 versus 8.2+/-2.9%, respectively). Observations in the healthy group were similar when peak EMG(di) or CMAP(di,MS) were used to normalise EMG(di). Levels of neural respiratory drive were higher in chronic obstructive pulmonary disease patients than healthy subjects, and related to disease severity. Diaphragm compound muscle action potential could be used to normalise diaphragm electromyogram if volitional inspiratory manoeuvres could not be performed, allowing translation of the technique to critically ill and ventilated patients.

Sleep-disordered breathing in unilateral diaphragm paralysis or severe weakness.

Few data exist concerning sleep in patients with hemidiaphragm paralysis or weakness. Traditionally, such patients are considered to sustain normal ventilation in sleep. In the present study, diaphragm strength was measured in order to identify patients with unilateral paralysis or severe weakness. Patients underwent polysomnography with additional recordings of the transoesophageal electromyogram (EMG) of the diaphragm and surface EMG of extra-diaphragmatic respiratory muscles. These data were compared with 11 normal, healthy subjects matched for sex, age and body mass index (BMI). In total, 11 patients (six males, mean+/-sd age 56.5+/-10.0 yrs, BMI 28.7+/-2.8 kg x m(-2)) with hemidiaphragm paralysis or severe weakness (unilateral twitch transdiaphragmatic pressure 3.3+/-1.7 cmH(2)O (0.33+/-0.17 kPa) were studied. They had a mean+/-sd respiratory disturbance index of 8.1+/-10.1 events x h(-1) during non-rapid eye movement (NREM) sleep and 26.0+/-17.8 events x h(-1) during rapid eye movement (REM) sleep (control groups 0.4+/-0.4 and 0.7+/-0.9 events x h(-1), respectively). The diaphragm EMG, as a percentage of maximum, was double that of the control group in NREM sleep (15.3+/-5.3 versus 8.9+/-4.9% max, respectively) and increased in REM sleep (20.0+/-6.9% max), while normal subjects sustained the same level of activation (6.2+/-3.1% max). Patients with unilateral diaphragm dysfunction are at risk of developing sleep-disordered breathing during rapid eye movement sleep. The diaphragm electromyogram, reflecting neural respiratory drive, is doubled in patients compared with normal subjects, and increases further in rapid eye movement sleep.

Neural respiratory drive during apnoeic events in obstructive sleep apnoea.

For a given neural drive, oesophageal pressure during apnoeic episodes may differ from that during airflow, since inspiratory airflow and increased lung volume both reduce pressure generation. It was, therefore, hypothesised that diaphragm electromyography (EMG) may provide additional data to oesophageal pressure when used for the assessment of neural drive in patients with obstructive sleep apnoea, whose breathing is associated with variable airflow and changes in lung volume. Neural respiratory drive was assessed using diaphragm EMG recorded from multipair oesophageal electrodes in 12 patients with obstructive sleep apnoea. Oesophageal pressure was also recorded. The mean+/-sd inspiratory oesophageal pressure swing was 11.0+/-3.7 cmH(2)O during wakefulness, 38.2+/-15.7 cmH(2)O at the end of the apnoea and reduced to 28.5+/-10.4 cmH(2)O at the beginning of arousal. The mean peak inspiratory diaphragm EMG signal was 21.8+/-6.5 muV during wakefulness, 38.6+/-14.0 muV at the end of the apnoea and further increased to 59.6+/-32.0 muV at the beginning of arousal. It was concluded that the pattern of neural drive assessed by oesophageal pressure differs from that measured by diaphragm electromyography during apnoeic events and, therefore, that diaphragm electromyography may be a useful adjunct to measurement of oesophageal pressure for the assessment of neural drive in patients with obstructive sleep apnoea.

Distribution of polycyclic aromatic hydrocarbons in thirty typical soil profiles in the Yangtze River Delta region, east China.

Polycyclic aromatic hydrocarbons (PAHs) were quantified in 30 soil profiles from the Yangtze River Delta Region, in east China. Relative concentrations of PAH compounds with different benzene rings and ratios of fluoranthene to fluoranthene plus pyrene and benz(a)anthracene to benz(a)anthracene plus chrysene were used to identify the possible sources of soil PAHs. Total concentrations of 15 PAHs in topsoils ranged from 8.6 to 3881 microg kg(-1) with an average of 397 microg kg(-1). Half of the soil samples were considered to be contaminated with PAHs (>200 microg kg(-1)) and two sampling sites were heavily polluted by PAHs with concentrations >1000 microg kg(-1). Phenanthrene was found in soils below a depth of 100 cm in half of the sampling sites, but the detectable ratio of benzo(a)pyrene decreased sharply from 100% in topsoil to 0 in the 4th horizon.