Respiratory Failure Group Research Articles

A porcine polytrauma model with two different degrees of hemorrhagic shock: outcome related to trauma within the first 48h.

BackgroundAn animal polytrauma model was developed, including trunk and extremity injuries combined with hemorrhagic shock and a prolonged post-traumatic phase. This could be useful for the assessment of different therapeutic approaches during intensive care therapy.MethodsA standardized polytrauma including lung contusion, liver laceration and lower leg fracture was applied in 25 pigs. They underwent controlled haemorrhage either with a blood volume loss of 45 % and a median arterial pressure (MAP) <30 mmHg/90 min (group L, n = 15) or a 50 % blood loss of and an MAP <25 mmHg/120 min (group H, n = 10). Five non-traumatized pigs served as a control (group C). Subsequently, intensive care treatment was given for an observational period of 48 h.ResultsBoth trauma groups showed signs of shock and organ injury (heart rate, MAP and lactate). The frequency of cardiopulmonary resuscitation (CPR) and lung injury was directly related to the severity of the haemorrhagic shock (CPR—group L: 4 of 15 pigs, group H: 4 of 10 pigs; Respiratory failure—group L: 3 of 13, group H: 3 of 9. There was no difference in mortality between trauma groups.ConclusionThe present data suggest that our model reflects the mortality and organ failure of polytrauma in humans during shock and the intensive care period. This suggests that the experimental protocol could be useful for the assessment of therapeutic approaches during the post-traumatic period.

Thyroid function in respiratory failure patients

BackgroundThe non thyroidal illness syndrome (NTIS) represents a risk factor for prolonged mechanical ventilation in mechanically ventilated, critically ill patients admitted to the ICU. It is unclear, whether the NTIS is only a biochemical prognostic marker or it actually contributes to the development and progression of respiratory failure. AimTo assess the thyroid function in patients with respiratory failure and to evaluate the impact of thyroid dysfunction as well as thyroid hormone replacement therapy on patients’ outcome. Patients and methodsThe study was conducted on 100 patients (51 females and 49 males), they were divided into two groups, Group A (respiratory failure group), who were admitted to the Respiratory ICU (RICU) and group B (non-respiratory failure group) who were admitted to the Inpatient Chest Department of Zagazig University Hospitals Egypt. The respiratory failure group (Group A) included sixty-four (64) patients with respiratory failure (according to ABG parameters) 30 males and 34 females. They included 30 patients with acute exacerbation of COPD, 5 patients with acute severe bronchial asthma, 5 patients with severe pneumonia, 4 patients with acute pulmonary embolism, 8 patients with ARDS and 12 patients with acute exacerbation of IPF. This respiratory failure group included 43 patients who were on invasive mechanical ventilation and 21 respiratory failure patients who were non-mechanically ventilated. Group (B) included thirty-six (36) patients without respiratory failure according to ABG parameters as a control group (19 males and 17 females). There were 11 patients with acute exacerbation of COPD, 10 patients with exacerbated bronchial asthma, 6 patients with exacerbated IPF, 6 patients with pneumonia and 3 patients with acute pulmonary embolism. All patients were subjected to calculation of APACHE Π score, PaO2/FiO2 ratio and estimation of thyroid hormones (TSH, free T3 and free T4) at the 1st, 3rd and 10th day of admission. Those who were still having ESS at the 10th day (16 patients) and were not improving clinically, were subdivided randomly into two subgroups. Each of them comprised 8 patients. One group was given l-thyroxin replacement therapy (The replacement group) beside conventional appropriate management. The other group (8 patients) was followed by conventional appropriate management only without replacement therapy (The non-replacement group). l-Thyroxine 100μg daily is administered for 7weeks. At the 7th week, a fourth set of thyroid hormone estimation was done for the patients of the replacement and non-replacement groups. Patients’ outcome was assessed after 7weeks of admission and labeled as the following: 1-death, 2-successfully treated and discharged. ResultsRespiratory failure patients showed evidence of euthyroid sick syndrome (ESS) at the 1st, 3rd and 10th days of admission with a frequency of 31.2%, 79.6% and 43.7% respectively while none of the control group showed evidence of (ESS) and the difference was statistically significant. There were highly significant negative correlation between serum levels of free T3 and TSH and each of the duration of mechanical ventilation and length of ICU stay. There was significant negative correlation between APACHE Π score and serum level of freeT3 in the respiratory failure group. There was non significant impact of thyroid hormone levels on patients’ outcome. There was non significant difference in the levels of thyroid hormones between replacement and non replacement groups at the 7th week of the study. ConclusionA state of hypothyroidism or euthyroid sick syndrome (ESS) is commonly found among patients with respiratory failure and this is related to the severity of the disease. ESS represents a risk factor for prolonged mechanical ventilation and length of ICU stay. l-thyroxin replacement therapy has no significant impact on patients’ outcome.

Time to Intubation Is Associated with Outcome in Patients with Community-Acquired Pneumonia

IntroductionIt has been suggested that delayed intensive care unit (ICU) transfer is associated with increased mortality for patients with community-acquired pneumonia (CAP). However, ICU admission policies and patient epidemiology vary widely across the world depending on local hospital practices and organizational constraints. We hypothesized that the time from the onset of CAP symptoms to invasive mechanical ventilation could be a relevant prognostic factor.MethodsOne hundred patients with a CAP and necessitating invasive mechanical ventilation were included. Prospectively collected data were retrospectively analysed. Two study groups were identified based on the time of the initiation of invasive mechanical ventilation (rapid respiratory failure requiring mechanical ventilation within 72 h of the onset of CAP and progressive respiratory failure requiring invasive mechanical ventilation 4 or more days after the onset of CAP).ResultsExcepting more COPD patients in the rapid respiratory failure group and more patients with diabetes in the progressive respiratory failure group, these patients had similar characteristics. The overall in-hospital mortality rate was 28% in the rapid respiratory failure group and 51% in the progressive respiratory failure group (P = 0.03). The ICU and the day 30 mortality rates were higher in the progressive respiratory failure group (47% vs. 23%, P = 0.02; and 37.7% vs. 21.3%, P = 0.03; respectively). After adjusting for the propensity score and other potential confounding factors, progressive respiratory failure remained associated with hospital mortality only after 12 days of invasive mechanical ventilation.ConclusionsThis study suggested that the duration or delay in the time to intubation from the onset of CAP symptoms was associated with the outcomes in those patients who ultimately required invasive mechanical ventilation.

Neonatal and Infant Mandibular Distraction as an Alternative to Tracheostomy in Severe Obstructive Sleep Apnea

Surgical management for severe obstructive sleep apnea has been tracheostomy, which has significant morbidity. To determine the efficacy of internal mandibular distraction in treating severe obstructive sleep apnea in infants and neonates. Retrospective review of medical records of 29 patients who underwent internal mandibular distraction for obstructive sleep apnea secondary to micrognathia. Nonprofit, academic, pediatric medical center. A total of 29 infants with obstructive sleep apnea were studied. Nine were included in the respiratory failure group requiring intubation prior to distraction surgery. The other 20 were included in the respiratory distress group and underwent preoperative polysomnography that assessed the severity of obstructive sleep apnea as measured by the apnea-hypopnea index. One patient expired following surgery; the remaining 28 underwent postoperative polysomnography determining their postoperative apnea-hypopnea index. Bilateral mandibular distraction with internal microdistractors. Improvement in the apnea-hypopnea index or extubation. The nine respiratory failure patients avoided tracheostomy and were successfully extubated postdistraction. Eight in this group had postoperative polysomnographies showing a mean apnea-hypopnea index of 3.13 (range, 0 to 13.9). All 20 patients in the respiratory distress group underwent polysomnography and showed improved apnea-hypopnea indices (p < .001). The mean pre-op apnea-hypopnea index was 39.7 (range, 4.5 to 177), and the mean post-op apnea-hypopnea index was 5.8 (range, 0 to 34). Average improvement in the apnea-hypopnea index was 33.9. The mean follow-up period was 18.7 months (1.6 to 45.2 months). Infants with micrognathia and obstructive sleep apnea may avoid tracheostomy and its inherent risks and complications by undergoing internal mandibular distraction, which is a viable alternative to tracheostomy.

Serum D-dimer changes and prognostic implication in 2009 novel influenza A(H1N1)

BackgroundThe patients with Influenza A (H1N1) have a higher mortality compared with suffering from seasonal influenza. However, many clinical characteristics are still not clear. In the course of clinical treatment on H1N1, we found there were some apparent abnormal clinical indexes being detected at the preliminary diagnosis for severely ill patients, especially the obvious increasing of D-dimer. D-dimer may be associated with the prognosis of Influenza A (H1N1). MethodsPatients' clinical data (age, gender, body mass index, primary diseases, etc.) and the preliminary diagnostic clinical indexes including blood creatine kinase (CK), creatine kinase isoenzyme (CK-MB), lactic dehydrogenase (LDH), T cell subsets, blood gas analysis, D-dimer, activated partial thromboplastin time (APTT), prothrombin time (PT) and plasma fibrinogen (FG) were retrospectively analyzed. ResultsCompared with the non-respiratory failure group, the cases in respiratory failure group, especially in death sub-group have lower lymphocytes, higher LDH and D-dimer, as well as decreasing oxygenation index during the preliminary diagnosis(P<0.05). The disease severity (Apche II scores) was independently associated with preliminary oxygenation index and LDH (R2=0.511, p<0.01). The correlation analysis shows that there is a negative correlation between the D-dimer and oxygenation index (r=−0.510, P<0.01) in the preliminary diagnosis. Meanwhile, there is also a negative correlation between preliminary diagnostic D-dimer and the lowest oxygenation index after admission (r=−0.573, P<0.01). ConclusionsThe peripheral blood lymphocytes (including CD3, CD4 and CD8), LDH, oxygenation index and D-dimer detected in the preliminary diagnosis are important indexes that may affect the disease progress and prognosis of H1N1 patients. The significantly increased D-dimer and corresponding hyoxemia indicate the probability of formation of pulmonary microthrombus. Thus, it may be necessary to consider the anticoagulant therapy.

Outcome of patients with cystic fibrosis admitted to the intensive care unit: Is invasive mechanical ventilation a risk factor for death in patients waiting lung transplantation?

The admission of patients with cystic fibrosis (CF) to the intensive care unit (ICU) is controversial. Our aim was to study the long-term outcome of patients with CF who were admitted to the ICU and the effect of ventilation modality. The medical records of 104 admissions (1996-2006) of 48 patients with CF (age 18+/-9 years) were reviewed. Seventeen patients were admitted with reversible conditions (group 1). Thirty-one patients were admitted for acute on chronic respiratory failure (group 2). In group 1, 16 of 17 patients survived up to 10 years from ICU admission. Conversely, in group 2, 23 of 31 patients (74%) died of respiratory failure. In group 2, 17 of 18 patients who were mechanically ventilated died within 90 days from admission, and 7 of 10 patients treated for prolonged periods with bi-level positive airway pressure are still alive up to 10 years after admission and transplantation. Patients requiring mechanical ventilation may have a poor prognosis. The outcome of treatment with bi-level positive airway pressure is good, even in patients who had many episodes of acute respiratory failure.

Surgical lung biopsy for diffuse pulmonary disease: Experience of 196 patients

Surgical lung biopsy is considered the final method of diagnostic modality in patients with undiagnosed diffuse pulmonary disease. Nevertheless, the effect of surgical lung biopsy on the diagnosis, treatment, and outcome of the patient still remains controversial. This study reviewed the experiences of surgical lung biopsies in 196 consecutive patients during the past 7 years. Surgical lung biopsy was performed after achievement of general anesthesia through video-assisted thoracoscopic surgery or a 7-cm minithoracotomy. Biopsy specimens were swabbed for aerobic and anaerobic bacterial, fungal, and mycobacterial cultures. The sections of specimens were routinely stained with hematoxylin and eosin, and acid-fast, Gomori methenamine silver, Gram stain, or other special stains were added if necessary. The pathologic diagnosis after surgical lung biopsy included infection (30.6%), interstitial pneumonia or fibrosis (21.9%), diffuse alveolar damage (17.3%), neoplasm (13.3%), autoimmune diseases (8.2%), and others (8.2%). After surgical lung biopsy, 165 (84.2%) patients had changes in their therapy, 124 (63.3%) patients had clinical improvement of their conditions, and 119 (60.7%) patients survived to hospital discharge. Comparison between immunocompromised and immunocompetent patients showed that diagnosis of infection was significantly higher ( P < .01) in the former group (41.2% vs 20.2%). In addition, there was no significant difference in the distribution of diagnosis and rate of change in therapy between the respiratory failure and nonrespiratory failure groups. However, the rates of response to therapy and patient survival were significantly lower in the respiratory failure group (51.2% and 41.5%) than in the nonrespiratory failure group (71.9% and 78.1%, P < .05). There was no surgical mortality directly related to the procedure. The surgical morbidity rate was 6.6%. Surgical lung biopsy is a safe and accurate diagnostic tool for diffuse pulmonary disease. For a large proportion of the patients, change of therapy and then clinical improvement can be achieved after surgical lung biopsy. Surgical lung biopsy should be considered earlier in patients with undiagnosed diffuse pulmonary disease, especially when the respiratory condition is deteriorating.

Most Common Intoxication in Nephrology Ward Organophosphate Poisoning

Objectives. In Taiwan, the widespread use of organophosphates (OPs) in agricultural and household environments results in numerous OP poisoning. To better understand the clinical significance of associated parameters on respiratory failure and patient outcome, we evaluate patients admitted to the Nephrology ward in our hospital with OP intoxication. Patients and Methods. Over a period of 2 years, a total of 42 consecutive patients with OP poisoning admitted to the nephrology ward or the Intensive Care Unit of Chang‐Gung Memorial Hospital were the subjects in the study. The diagnosis of poisoning was based on history of ingestion and characteristic clinical features of anticholinesterase agent poisoning. Prior to treatment, all symptoms recorded at emergency room and blood samples for blood chemistry including plasma amylase and plasma acetyl‐cholinesterase were collected from each patient immediately after the admission. Results. As clinical manifestations of OP show, nausea and vomiting and salivation were the leading manifestations, 45.2% and 33.3%, respectively. Patients who developed respiratory failure were older than those who did not (54.3 ± 6.9 vs. 43.1 ± 5.6, p < 0.05). The dosage of atropine administered for treatment was significantly higher in the patient group with respiratory failure compared to those without respiratory failure (29.7 ± 14.5 vs. 9.1 ± 10.2, p < 0.05). Plasma amylase level of the patient group with respiratory failure was significantly higher than those without respiratory failure (436.1 ± 87.1 vs. 181.3 ± 29.6, p < 0.01). Of course, mean days of hospitalization in the respiratory failure group are significantly longer than the other group (12.1 ± 2.1 vs. 5.4 ± 1.9, p < 0.05). Based on univariant analysis, bradycardia, hypotension, fasciculation and coma were significant factors associated with respiratory failure. The dose of atropine administered for treatment was significantly higher in the oral exposure group compared to nonoral exposure group (23.6 ± 12.6 vs. 10.6 ± 6.4, p < 0.05). The same is true for the pralidoxime treatment (9.6 ± 1.9 vs. 5.3 ± 1.4, p < 0.05). As for mean days of hospitalization (11.6 ± 3.9 vs. 6.4 ± 2.1, p < 0.05) and fatality (2 vs. 0, p < 0.05), those of oral exposure patients were significantly longer and higher than those with nonoral exposure. Conclusions. We demonstrate that elevated plasma amylase concentration was related to the development of respiratory failure in OP intoxication. It also provided us various important risk factors to identify those patients with OP poisoning who would ultimately require ventilatory support.

Evaluation of cardiopulmonary exercise test on predicting post-operative respiratory failure in patients with lung cancer

To evaluate the clinical significance of predicting post-operative respiratory failure in patients with lung cancer using cardiopulmonary exercise test (CPET). Before operation, 260 patients with lung cancer underwent CPET with incremental protocol. W%, VO₂%P, VO₂/kg, AT, MET, O₂ pulse, VTe, BF and VE were measured in the end of load exercise. (1) In patients after pneumonectomy, the values of the above indexes of CPET in the respiratory failure group were significantly lower than those in the non-respiratory failure group ( P < 0.05 or P < 0.01) except VTe. In patients after lobectomy, the values of 9 indexes of CPET in the respiratory failure group were similar to those in the non-respiratory failure group ( P > 0.05). However, when the patients after lobectomy were further divided into groups of upper and lower lobectomy, W% in the respiratory failure group was remarkably lower than that in the non-respiratory failure group after lower lobectomy ( P < 0.05). (2) Chi-Square test showed that abnormality of CPET indexes in different degrees was related to the morbidity of respiratory failure after pneumonectomy. Logistic regression showed that O₂ pulse < 80% and BF < 30/min correlated with the morbidity of post-operative respiratory failure. (3) For predicting post-operative respiratory failure, the sensitivity and specificity of VO₂%P < 60%, BF < 30/min, VE < 35 L/min were all more than 60% and their negative predictive values were all more than 90%. CPET is suitable to predict post-pneumonectomy respiratory failure. As a comprehensive index indicating cardiopulmonary function during exercise, VO₂%P < 60% should be selected to predict respiratory failure and evaluate indication of lung resection for patients with lung cancer.

Forgoing life-sustaining treatments: how the decision is made in French pediatric intensive care units.

The decision to forgo life support is frequently made in pediatric intensive care units (PICUs). A group of experts is currently preparing recommendations for guidelines concerning this decision-making process in France. We have performed a prospective study to help the experts. This study documents how children die in French PICUs and how the decision to limit life support is made. A multicenter, prospective, cross-sectional study. Thirty-three multidisciplinary PICUs in university hospitals. All consecutive deaths were recorded over a 4-month period. Children who died after a medical decision to forgo life-sustaining treatment were included in group 1 and children who died from other causes were included in group 1. A total of 264 consecutive children died, 40.1% from group 1 and 59.8% from group 2. Patients of both groups were primarily admitted for acute respiratory failure (group 1, 50.8%; group 2, 52.6%). Neurologic emergencies were more frequent in patients in group 1, whereas patients with cardiovascular failures were more frequent in group 2. When there was a question of whether to pursue life-sustaining treatment, the parents' opinions were recorded in 72.1% of cases. A specific meeting was called to make this decision in 80.1% of cases. This meeting involved the medical staff in all cases. Parents were aware of the meeting in 10.7% of cases. The conclusion of the meeting was reported to the parents in 18.7% of cases and documented in the patient's medical record in 16% of cases. Experts who were not members of the PICU staff were invited to give their opinion in 62.2% of cases. The decision to forgo life-sustaining treatment is frequently made for children dying in French PICUs. Guidelines must be available to help the medical staff reach this decision. Knowledge of the decision-making process in French PICUs provides the experts with information needed to elaborate such recommendations.

Pediatric noninvasive positive pressure ventilation.

OBJECTIVE: To review the clinical use of noninvasive positive pressure ventilation (NPPV) in both acute hypoxic and hypercarbic forms of pediatric respiratory failure, including its mechanism of action and implementation. DATA SOURCES: Studies were identified through a MEDLINE search using respiratory failure, pediatrics, noninvasive ventilation, and mechanical ventilation as key words. STUDY SELECTION: All original studies, including case reports, relating to the use of noninvasive positive pressure in pediatric respiratory failure were included. Because of the paucity of published literature on pediatric NPPV, no study was excluded. DATA EXTRACTION: Study design, numbers and diagnoses of patients, types of noninvasive ventilator, ventilator modes, outcome measures, and complications were extracted and compiled. DATA SYNTHESIS: For acute hypoxic respiratory failure, all the studies reported improvement in oxygenation indices and avoidance of endotracheal intubation. The average duration of NPPV therapy before noticeable clinical improvement was 3 hrs in most studies, and NPPV was applied continuously for 72 hrs before resolution of acute respiratory distress. In patients with acute hypercarbic respiratory failure, application of NPPV resulted in reduction of work of breathing, reduction in CO(2) tension, and increased serum bicarbonate and pH. These patients are older than patients in the acute hypoxic respiratory failure group and, in addition to improved blood gas indices, they reported improvement in subjective symptoms of dyspnea. Improvement in gas exchange abnormalities and subjective symptoms occurred within the same time span (the first 3 hrs) as in the acute hypoxic respiratory failure group. However, use of noninvasive techniques in patients with acute hypercarbic respiratory failure continued after resolution of acute symptoms. Complications related to protracted use of NPPV were common in this group. CONCLUSIONS: NPPV has limited benefits in a group of carefully selected pediatric patients with acute hypoxic and hypercarbic forms of respiratory failure. The routine use of this technique in pediatric respiratory failure needs to be studied in randomized controlled trials and better-defined patient subsets.

Risky factors of post-operative respiratory failure in patients with lung cancer.

To analyze the risky factors of post-operative respiratory failure in patients with lung cancer. Thirty-six cases of lung cancer with post-operative respiratory failure and 72 controls were analyzed by Chi-Square analysis and Logistic Regression. MVV , RV/ TLC , FEV1 , BR , V25 , MMEF and DLCO in respiratory failure group were all significantly lower than those in control group ( P < 0. 05) . The post-operative chest drainage and perioperative intravenous perfussion in respiratory failure group were significantly more than those in control group ( P < 0. 05) . The odds of respiratory failure was much lower in sleeve resection and lobectomy group than in pneumonectomy group. Severe obstruction of small airway , diffusion capacity and large amount perioperative intravenous infusion are the risky factors of post-operative respiratory failure in lung cancer patients , and bronchoplastic or/ and pulmonary artery reconstruction as a curative operation can significantly prevent the post-operative respiratory failure.

Analysis of factors that characterize health impairment in patients with chronic respiratory failure. Quality of Life in Chronic Respiratory Failure Group.

This study was designed to identify a core set of items that may characterize impaired health in chronic respiratory failure (CRF) since none of the questionnaires commonly used to measure impaired health in patients with CRF were developed for use in such patients. Questionnaire items, identified from several sources, were administered to 92 patients with stable severe chronic hypoxia or hypercapnia, together with physiological measures of disease severity, the Sickness Impact Profile (SIP) and the St George's Respiratory Questionnaire (SGRQ). Of the 152 items identified, only 28 correlated with patients' perceptions of overall health and were also independent of age, sex, disease or type of treatment and did not show floor or ceiling effects. Principal components analysis identified three specific factors: "daily activities", "cognitive function", and "invalidity". The total score for the whole 28-item set correlated with other measures of disease activity, including SGRQ (r = 0.86) and SIP (r = 0.70), but not spirometry. The interquartile range of the 28-item set was wider than that of the SGRQ or the SIP. This study characterized two areas of health impairment in chronic respiratory failure that had not previously been identified: effects of impaired cognitive function on daily life, and a sense of invalidity. The measurements properties of this 28-item set suggest that it may be a more discriminative instrument for patients with chronic respiratory failure than existing questionnaires.

Pulmonary mechanics in infants after cardiac surgery

To determine pulmonary mechanical characteristics in neonates after cardiac surgery. A prospective study. A 23-bed, pediatric ICU in a 280-bed children's hospital. Twenty-six infants on the first post-operative day after cardiac surgery. Pulmonary mechanics measurements were made during spontaneous breathing, using the esophageal balloon technique and a pneumotachometer. The least mean square method of analysis was used to calculate mechanics. Infants who tolerated withdrawal of mechanical ventilation (group 1) were compared with those infants with respiratory failure (group 2). Spontaneous respiratory rate, tidal volume, and minute ventilation were similar in groups 1 and 2. Lung compliance was decreased, with no difference between groups. Total lung resistance (34.3 +/- 21.6 cm H2O/L.sec in group 1 vs. 136.8 +/- 105.8 cm H2O/L.sec in group 2, p = .002) and resistive work of breathing (33.4 +/- 29.9 g.cm/kg in group 1 vs. 212.9 +/- 173.8 g.cm/kg in group 2, p = .001) were significantly higher in group 2. All infants with a total lung resistance greater than 75 cm H2O/L.sec exhibited respiratory failure (resistance greater than 75 cm H2O/L.sec correlated with respiratory failure, r2 = .73, odds ratio of 70 [confidence interval, 4.4 to 3240], p less than .001). Increased lung resistance identifies neonates with respiratory failure after cardiac surgery. Pulmonary mechanics testing may be useful in timing withdrawal of mechanical ventilation.

Respiratory muscle insufficiency in acute respiratory failure of subjects with severe COPD: treatment with intermittent negative pressure ventilation

Nine subjects with severe chronic obstructive pulmonary disease (COPD) in acute respiratory failure (ARF) and with marked weakness of the respiratory muscles (Group A) underwent intermittent negative pressure ventilation by means of an iron lung (8 h daily for 7 days). Seven subjects with COPD in stabilized chronic respiratory failure (Group B) were studied as controls and submitted to the same medical therapy without ventilator treatment. Functional respiratory tests were performed before and after 7 days of treatment. After ventilatory treatment, Group A showed an increase of maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), vital capacity (VC), arterial oxygen tension (PaO2), pH and a decrease of residual volume (RV), total lung capacity of (TLC) and arterial carbon dioxide tension (PaCO2) (all statistically significant). No improvement was ascertained in the functional parameters of Group B. The expiratory muscles seem to play a determining role in ARF. We conclude that the iron lung is a useful therapeutic defence in removing muscular fatigue and in restoring a good level of respiratory compensation of ARF in severe COPD.

Prognostic evaluation of congestive heart failure in patients with Duchenne muscular dystrophy--retrospective study using non-invasive cardiac function tests.

The relation between heart function and the prognosis of patients with Duchenne muscular dystrophy (DMD) was analyzed in 27 non-survivors and 40 survivors by fractional shortening (FS) of the left ventricle from M-mode echocardiogram, and by the PEP/ET ratio from the systolic time interval. The patients were divided into 5 groups; (1) patients who died of congestive heart failure (group 1), (2) those who died of congestive heart failure and respiratory failure (group 2), (3) those who died of respiratory failure (group 3), (4) those who died suddenly of undefined etiology (group 4), and (5) survivors (group 5). Data from non-invasive cardiac function tests were analyzed retrospectively for 2 years and compared at 2 years, 1 year and about 3 months before their deaths in cases of group 1, 2, 3 and 4, and the data obtained at the same period were also compared with those of survivors (group 5). The age at death in group 1 (17.3 +/- 4.9 years) was significantly younger than that in group 2 (25.3 +/- 4.2 years), however, it did not statistically differ from group 3 (19.8 +/- 3.3 years old). The values of FS in group 1 were significantly lower than those in group 3, 4 and 5 at three examinations, whereas no difference in PEP/ET was observed among them. Cardiothoracic ratio (CTR) on chest X-ray in group 1 was not significantly different from other groups in each period, but the left ventricle dilated rapidly in the terminal stage of congestive heart failure which could be more precisely detected by the M-mode echocardiogram. These results indicate that in DMD, early development of congestive heart failure was associated with a poor prognosis. FS was a most sensitive non-invasive tool in predicting the prognosis. A significant reduction in FS was detectable 2 years before death. Progression in abnormality of left ventricular dimension as well as in FS may be another useful index for evaluating the prognosis of patients dying from congestive heart failure.

Oxygen Uptake during Weaning from Mechanical Ventilation

Total body oxygen uptake (VO2) increases during the transition from machine-assisted ventilation to spontaneous breathing. Since the volume of oxygen consumed by the respiratory muscles must contribute to the increase in VO2 (delta VO2), we explored whether delta VO2 and/or measurements of respiratory power output (Wresp) provide clinically useful information in the evaluation of disease state and weaning decisions in patients with respiratory failure. We determined the metabolic, ventilatory, and hemodynamic responses of ten patients during weaning from controlled mechanical ventilation, and compared delta VO2 and Wresp of patients without overt heart-lung disease (group 1) to that of patients with significant cardiopulmonary dysfunction and ventilator-dependent respiratory failure (group 2). We reasoned that for delta VO2 to be clinically useful, individual values must either clearly differ between groups, must be higher in patients with heart-lung disease, and/or correlate with weaning outcome and independent measurements of respiratory work. The VO2 increased in nine of ten patients. The differences between the groups in the values of delta VO2 (27 ml/min and 49 ml/min) and respiratory power (9.38 J/min and 11.99 J/min) were not significant. delta VO2 and Wresp were not correlated (r = 0.2), and neither predicted weaning outcome. We conclude that the sensitivity and specificity of delta VO2 and Wresp appear insufficient for evaluation of disease state and weaning decisions in individual patients.

Effects of captopril on pulmonary haemodynamics

The effects of oral captopril on pulmonary haemodynamics were studied in two groups of 6 patients, one of subjects with chronic respiratory failure (PaO2 52 +/- 5.1 mmHg, PaCO2 54 +/- 2.1 mmHg), and the others with chronic heart failure and high plasma renin activity. Two potential mechanisms of its actions were assessed, namely inhibition of hypoxic vasoconstriction and inhibition of the possible effects of angiotensin II on the pulmonary circulation. There were significant (p less than 0.05) decreases in mean arterial pressure, pulmonary wedge pressure and in systemic arterial resistance associated with improvement in cardiac index in both groups. In the chronic respiratory failure group there was no change in blood gases, mean pulmonary arterial pressure or pulmonary vascular resistance. An increase in driving pressure (p less than 0.05) indicated that captopril had had no effect on pulmonary haemodynamics. In chronic heart failure, mean pulmonary arterial pressure and pulmonary capillary wedge pressure were decreased by a similar extent, so that driving pressure and pulmonary vascular resistance were not changed. It is concluded that oral captopril did not inhibit hypoxic vasoconstriction, and that it modified pulmonary haemodynamics in chronic heart failure patients with high renin activity only as a consequence of reduction in systemic afterload.

Nutritional Assessment of Patients with Chronic Obstructive Pulmonary Disease and Acute Respiratory Failure

In order to determine the likelihood of pre-existing nutritional deficits in medical patients with acute respiratory failure, a nutritional assessment survey was performed on 18 control patients with stable COPD and nine patients with COPD and acute respiratory failure. Significant differences were noted with the respiratory failure group having deficits in percentage of ideal body weight (mean difference 19 percent), triceps skinfold thickness (mean difference 4.4 mm), and arm muscle circumference (mean difference 3.3 cm). Significant deficits were also found in measurements of serum transferrin and retinol binding proteins, creatinine height index and total lymphocyte counts. Body protein and fat stores were markedly depleted in almost half of the patients with respiratory failure. These data suggest that protein-calorie malnutrition is likely to be present in patients with COPD and acute respiratory failure. Nutritional support for this population should be initiated at the onset of the illness. Nutritional repletion should be considered one goal of such therapy.

Changes in arterial blood gases during and after a period of oxygen breathing in patients with chronic hypercapnic respiratory failure and in patients with asthma.

1. Ten patients with chronic hypercapnic respiratory failure (group 1) and eight patients with asthma (group 2) breathed pure O2 from an MC mask for 60 min. Blood gases were measured during this period and for the subsequent 45 min. 2. In mine of ten patients in group 1 and in all eight patients in group 2 arterial O2 tension (Pa,O2) fell to values lower than had been obtained before O2 was given. 3. These undershoots in Pa,O2 are unrelated to changing CO2 stores or to hypoventilation, and are more likely due to persistence of altered ventilation-perfusion ratios associated with O2 breathing. 4. Magnitude of the undershoots is usually small, and periods of less than 15 min of O2 are unlikely to be harmful.