Silverio Santiago

Nasal mechanical ventilation for hypercapnic respiratory failure in chronic obstructive pulmonary disease: Determinants of success and failure

To evaluate the efficacy of nasal mechanical ventilation in patients with chronic obstructive pulmonary disease and hypercapnic respiratory failure and to identify predictors of success or failure of nasal mechanical ventilation. Design:Prospective case series. Setting:Medical intensive care unit in Veterans Administration Medical Center. Patients:Twelve chronic obstructive pulmonary disease patients treated during 14 episodes of hypercapnic respiratory failure. Interventions:Nasal mechanical ventilation in addition to conventional therapy to treat hypercapnic respiratory failure. Patients underwent nasal mechanical ventilation for at least 30 mins, or longer if the therapy was tolerated. Responses to therapy and arterial blood gases were monitored. Measurements and Main Results:Half of the episodes were successfully treated with nasal mechanical ventilation. There were no differences hi age, prior pulmonary function, baseline arterial blood gases, admission arterial blood gases, or respiratory rate between those patients successfully treated and those patients who failed nasal mechanical ventilation. Unsuccessfully treated patients appeared to have a greater severity of illness than successfully treated patients, as indicated by a higher Acute Physiology and Chronic Health Evaluation II score (mean 21 × 4 [SD] VS. 15 ±4; p = .02). Unsuccessfully treated patients were edentulous, had pneumonia or excess secretions, and had pursed-lip breathing, factors that prevented adequate mouth seal and contributed to greater mouth leaks than in successfully treated patients (the mean volume of the mouth leak was 314 ±107 vs. 100 ±70 mL; p < .01). Successfully treated patients were able to adapt more rapidly to the nasal mask and ventilator, with greater and more rapid reduction in Paco2, correction of pH, and reduction hi respiratory rate. Conclusions:Patients who failed nasal mechanical ventilation appeared to have a greater severity of illness; they were unable to minimize the amount of mouth leak (because of lack of teeth, secretions, or breathing pattern) and were unable to coordinate with the ventilator. These features may allow identification of poor candidates for nasal mechanical ventilation, avoiding unnecessary delays in endotracheal intubation and mechanical ventilation. (Crit Care Med 1994; 22:1253–1261)

Sleep apnea syndrome and essential hypertension.

More than half of patients with essential hypertension have sleep apnea. The incidence of unrecognized sleep apnea in patients with essential hypertension was assessed. Twenty-three patients taking antihypertensive medication were selected at random from a hypertension clinic. They were evaluated by questionnaire for symptoms of sleep apnea, and during 3 hours of sleep, measurements were made of respiratory patterns using an impedance pneumograph, arterial O2 saturation with an ear oximeter and air flow at the mouth or nose with a face mask pneumotacograph. Abnormal sleep apneas (average 20 seconds) lasting for an average of 19% sleep time were found in 11 patients (48%). Significant arterial O2 desaturation, defined as a decrease of at least 4% and to less than 90%, was observed in 7 of these 11 (30%), with an average saturation of 87% at the end of the apneic episodes. Thus, almost one-third of patients randomly selected had significant arterial O2 desaturation during sleep because of sleep apnea, and it is suggested that sleep apnea may play a part in the development of essential hypertension.

Efficacy of pursed-lips breathing: a breathing pattern retraining strategy for dyspnea reduction.

PURPOSE: Breathing pattern retraining is frequently used for exertional dyspnea relief in adults with moderate to severe chronic obstructive pulmonary disease. However, there is contradictory evidence to support its use. The study objective was to compare 2 programs of prolonging expiratory time (pursed-lips breathing and expiratory muscle training) on dyspnea and functional performance. METHODS: A randomized, controlled design was used for the pilot study. Subjects recruited from the outpatient pulmonary clinic of a university-affiliated Veteran Affairs healthcare center were randomized to: 1) pursed-lips breathing, 2) expiratory muscle training, or 3) control. Changes over time in dyspnea [modified Borg after 6-minute walk distance (6MWD) and Shortness of Breath Questionnaire] and functional performance (Human Activity Profile and physical function scale of Short Form 36-item Health Survey) were assessed with a multilevel modeling procedure. Weekly laboratory visits for training were accompanied by structured verbal, written, and audiovisual instruction. RESULTS: Forty subjects with chronic obstructive pulmonary disease [age = 65 ± 9 (mean ± standard deviation) years, forced expiratory volume 1 second/forced vital capacity % = 46 ± 10, forced expiratory volume 1 second % predicted = 39 ± 13, body mass index = 26 ± 6 kg/m2, inspiratory muscle strength = 69 ± 22 cm H2O, and expiratory muscle strength (PEmax) = 102 ± 29 cm H2O] were enrolled. No significant Group × Time difference was present for PEmax (P = .93). Significant reductions for the modified Borg scale after 6MWD (P = .05) and physical function (P = .02) from baseline to 12 weeks were only present for pursed-lips breathing. CONCLUSION: Pursed-lips breathing provided sustained improvement in exertional dyspnea and physical function.

Idiopathic Pulmonary Fibrosis: Evaluation with Positron Emission Tomography

Background: The pathogenesis of interstitial lung disease remains under investigation, but may be related to increased inflammatory or cellular activity. This activity may be detectable with physiologic imaging. Objectives: We investigated the role of physiologic imaging using 18F-2-fluoro-2-deoxy-D-glucose (18FDG)-positron emission tomography (PET) scans in idiopathic pulmonary fibrosis (IPF). Methods: Seven male patients with histologically confirmed IPF underwent 18FDG-PET scans. Scans were analyzed qualitatively and interpreted as positive or negative. Patients also underwent pulmonary function tests and computed tomography (CT) scans. Results: The average total lung capacity was 71 ± 22% predicted (mean ± SD) and diffusing capacity for carbon monoxide was 44 ± 14% predicted. All had changes consistent with IPF on chest CT and 2 patients had ground glass attenuation. Six of seven patients (86%) had a positive 18FDG-PET scan. Changes in the 18FDG-PET scan were seen in 1 patient corresponding to changes in clinical status. Conclusions: Our findings suggest that 18FDG-PET scans may be helpful in the evaluation of IPF. Increased activity suggests active disease and changes in response to therapy.

Pulmonary Hypertension in Men with Thyrotoxicosis

Thyrotoxicosis has a myriad of respiratory symptoms including dyspnea. Pulmonary hypertension may contribute to the respiratory symptoms of thyrotoxicosis, but is often unrecognized. We describe 3 male patients with thyrotoxicosis and associated pulmonary hypertension. Case reports of an additional 15 patients are also reviewed. In patients with thyrotoxicosis and pulmonary hypertension, treatment of thyrotoxicosis alone is associated with improvement in pulmonary hypertension. Previous reports have consisted of mostly female patients, but we report 3 men. When all cases are considered, the typical patient is female (10/14 = 71%), middle-aged (48 years), with mean pulmonary artery systolic pressures improving from 56 to 32 mm Hg with treatment. Autoantibodies were detected in 10/14 (71%) patients. The response to treatment (medical or surgical) of thyrotoxicosis supports the hypothesis that hyperthyroidism is either a cause of pulmonary hypertension, or a factor that may unmask pulmonary hypertension. Recognition is important since treatment and response are very different compared to other patients with pulmonary hypertension. This association may not be readily considered in men, since most reports have been of women.

Mortality in status asthmaticus: A nine-year experience in a respiratory intensive care unit

Failure to recognize the severity of an asthmatic attack and its consequent lack of aggressive management have been incriminated as contributing factors in mortality from asthma. We reviewed our experience with patients in status asthmaticus admitted to the Respiratory Intensive Care Unit (RICU) over a nine-year period to determine the course and mortality of patients managed in the RICU. Between May, 1968, and April, 1977, 86 patients in status asthmaticus were admitted, 11 with multiple admissions, for a total of 111 admissions. There were two fatalities recorded. Psychological dependence on therapeutic modalities probably contributed to these two deaths, and both may have been preventable. The low mortality rate probably reflects the more intensive management and monitoring that these severe asthmatics receive in an RICU setting.

Pleuropulmonary infection due to Corynebacterium striatum

Corynebacterium striatum, a saprophytic diphtheroid in man, caused a pleuropulmonary infection in a patient with chronic lymphocytic leukaemia. This organism has not previously been described as a cause of human disease.

Multidomain subjective response to respirator use during simulated work

Objective: Evaluate subjective tolerance to respirator use outside of traditional industrial settings by users including persons with mild respiratory impairment. Methods: The response to respirator use (half face mask dual cartridge and N95) was measured during eight types of work activities as well as in an exercise laboratory setting. The 43 research subjects included persons with mild respiratory impairments. Multiple domains of subjective response were evaluated. Results: Mixed model regression analyses assessing the effect of respirator type and task type showed: 1) most tolerated respirator use well; 2) half face mask respirators typically had greater adverse impact than N95 types; 3) multiple subjective outcomes, rather than only comfort/breathing impact, should be measured; and 4) rated subjective impact during work activities is less than in exercise laboratory settings. Conclusions: The results suggest that respirator use may be feasible on a widespread basis if necessary in the face of epidemic or terror concerns.

Respirator Physiological Effects under Simulated Work Conditions

This study compared the physiological impacts of two respirator types in simulated work conditions. Fifty-six subjects included normal volunteers and persons with mild respiratory impairments (chronic rhinitis, mild COPD, and mild asthma). Respiratory parameters and electrocardiogram were measured using respiratory inductive plethysmography while performing eight work tasks involving low to moderate exertion using two respirators: (1) a dual cartridge half face mask (HFM) respirator, and (2) the N95. Mixed model regression analyses evaluating the effect of task and respirator type showed that task affected tidal volume, minute ventilation, breathing frequency and heart rate; all were greater in heavier tasks. Although respirator type did not affect respiratory volume parameters and flow rates, the HFM led to increase in the inspiratory time, reduction of the expiratory time, and increase in the duty cycle in comparison with the N95. The magnitude of differences was relatively small. The results suggest that most individuals, including persons with mild respiratory impairments, will physiologically tolerate either type of respirator at low to moderate exertion tasks. However, because effective protection depends on proper use, differences in subjective effect may have greater impact than physiological differences. Using respirators may be feasible on a widespread basis if necessary for maintaining essential services in the face of widespread concern about an infectious or terrorist threat.

Bronchoscopy in patients with haemoptysis and normal chest roentgenograms

We reviewed the records of 58 patients with haemoptysis and normal chest roentgenograms who underwent fibreoptic bronchoscopy. A diagnosis of malignancy was made in six patients at bronchoscopy. Three patients had bronchogenic squamous cell carcinoma, one a carcinoid tumour and two laryngeal carcinoma. Sputum for cytology was negative for malignant cells in all six patients. Follow-up data were available for the other 52 patients for an average period of 55.7 +/- 29.6 (SD) months. Two patients had a subsequent diagnosis of bronchogenic carcinoma at 2 and 6 years after initial evaluation. Three patients died from conditions not related to pulmonary malignancy and the remaining patients followed a benign course. Our patients come from a predominantly male, elderly population of cigarette smokers. Among such patients, we conclude that bronchoscopy is indicated in the evaluation of those with haemoptysis and a normal chest roentgenogram.