Search PubMed⌕ Search

Biomedical subjects

A J Block

Publications and source records attributed to A J Block.

At least 19 recordsLinked to original sources
PubMed1992

External stabilization of flail chest using continuous negative extrathoracic pressure.

On rare occasions after total sternectomy, patients develop persistent flail chest deformities requiring long-term mechanical respiratory assistance. We report the use of a temporary external chest shell to deliver constant negative extrathoracic pressure (CNEP) to a long-term ventilated patient with flail chest. The patient's anterior thoracic cage stabilized, and significant improvement in pulmonary function was observed. With these data in hand, an operation was done to permanently stabilize the anterior chest wall by bone grafting.

Aged↗
PubMed1979

Sleep apnea, hypopnea and oxygen desaturation in normal subjects. A strong male predominance.

Thirty asymptomatic men and 19 asymptomatic women were monitored during one night's sleep to determine the incidence of breathing abnormalities and oxygen desaturation in normal subjects. Twenty men accounted for 264 episodes of nocturnal oxygen desaturation or abnormal breathing. Women never experienced oxygen desaturation, and only three had a total of nine episodes of apnea. These sex differences were highly significant (P less than 0.003). In men, increasing age and obesity correlated positively with the incidence of nocturnal oxygen desaturation and abnormal breathing. Four asymptomatic men weighing more than 90 kg dropped their saturation to very low levels (68 to 72 per cent). Abnormal breathing and oxygen desaturation during sleep in subjects with chronic obstructive lung disease of the syndrome of hypersomnolence with periodic breathing may represent the superimposition of smoking or obesity on a normal tendency to snoring and oxygen desaturation in men.

Adult↗
PubMed1979

Disordered breathing and oxygen desaturation during sleep in patients with chronic obstructive lung disease (COLD).

Seven patients with chronic obstructive lung disease (COLD) were monitored during their overnight sleep to determine the occurrence of disordered breathing and oxygen desaturation. Nasal and oral airflows were sensed by thermistor probes, chest wall movement by impedance pneumography and arterial oxygen saturation by ear oximetry. These variables were correlated with electroencephalographic and electrooculographic tracings. The subjects had a mean base line oxygen saturation of 89.2 per cent and slept an average of 218 minutes. Six of these seven subjects had one to 30 episodes of oxygen desaturation (decrease more than 4 per cent), 4 seconds to 30 minutes in duration, with declines in saturation as great as 36 per cent. In two subjects, saturation dropped to less than 50 per cent. Breathing was disordered in five of the seven subjects and included apnea and hypopnea. Subjects experienced from nine to 37 episodes of disordered breathing. Disordered breathing caused 42 per cent of the episodes of desaturation, all of which were less than 1 minute in duration. The mean maximum decline in saturation was 7.6 per cent. All episodes of desaturation lasting longer than 5 minutes occurred in rapid eye movement (REM) sleep and were not caused by disordered breathing. The mean maximal decrease in saturation was 22 per cent. This study reveals that disordered breathing is common in subjects with COLD and often causes desaturation but that it cannot explain all episodes of sleep desaturation.

Adult↗
PubMed1979

Nocturnal vs diurnal cardiac arrhythmias in patients with chronic obstructive pulmonary disease.

Continuous electrocardiograms were recorded from ten patients with chronic obstructive pulmonary disease. During 24 hours of recording, the patients breathed air; and for 24 hours, they breathed oxygen at 2 L/min by nasal cannula. Oxygenation, as monitored by ear oximetric studies and by periodic analysis of arterial blood, showed frequent nocturnal desaturation. Nine patients demonstrated arrhythmias during the monitoring period, and the frequency of premature ventricular contractions was significantly greater at night. Therapy with supplemental oxygen dramatically reduced the frequency of premature ventricular contractions in four patients, but the reduction in frequency of arrhythmias in the total group did not reach statistical significance. These results show that cardiac arrhythmias occur commonly at night during sleep in patients with chronic obstructive pulmonary disease. The data suggest that arterial desaturation may be responsible for some of these arrhythmias.

Aged↗
PubMed1979

Nocturnal pulmonary hypertension in patients with chronic obstructive pulmonary disease.

Oxygen desaturation occurs during sleep in some patients with COPD. To investigate the effects of these hypoxemic episodes on the pulmonary vasculature, we studied four patients with our routine polysomnographic techniques and simultaneously recorded pulmonary artery pressure. In all four subjects, nocturnal episodes of desaturation were accompanied by elevations in the pulmonary artery pressure. Low flow oxygen abolished the drops in arterial oxygen saturation (but not the breathing abnormalities) and no elevations in the PA pressure were observed. We postulate that in some COPD patients these initially transient events may lead to sustained pulmonary hypertension and cor pulmonale. Nocturnal oxygen therapy may be indicated in more patients than previously suspected and may prevent the development of cor pulmonale.

Adult↗
PubMed1978

Legionnaires' disease. A sporadic case.

A patient with Legionnaires' disease developed consolidated pneumonia with severe hypoxemia and mental confusion; his condition improved with therapy with positive end-expiratory pressure, steroids, and chloramphenicol. The retrospective diagnosis was made by a fourfold rise in indirect fluorescent antibody titers. The chest x-ray films showed bilateral alveolar infiltrates and air bronchograms.

Adult↗
PubMed1978

A new oxygen cannula system using intermittent-demand nasal flow.

A new cannula with a system of intermittent nasal flow was evaluated and compared with a standard constant-flow nasal cannula in 15 patients with chronic obstructive pulmonary disease. The intermittent-demand cannula released oxygen only when a negative pressure was detected in the nose (negative mode) or when a a positive pressure ceased to be detected in the nose (positive mode). At rates of flow varying from 0.63 to 5.60 L/min, the continuous-flow mode used 9 percent more oxygen than the negative mode and 31 percent more oxygen than the positive mode to achieve comparable improvement in arterial oxygen tension. The system using the intermittent-demand cannula was sensitive and reliable in over 150 hours of testing.

Adult↗
PubMed1978

Disordered breathing and oxygen desaturation during daytime naps.

Ten patients with and ten patients without chronic obstructive pulmonary disease (COPD) were monitored for the presence of disordered breathing and oxygen desaturation during daytime naps. Disordered breathing occurred commonly during naps in patients with COPD and often was associated with desaturation. Disordered breathing was also seen in patients without COPD, but desaturation was less frequent and less severe.

Adult↗
PubMed1977

Chronic oxygen therapy.

Chronic low flow oxygen is useful therapy for patients with chronic obstructive lung disease who are crippled by hypoxemia despite optimal programs of usual respiratory care. Patients should be considered for chronic oxygen therapy who have (a) a resting Pao2 less than 55 mm Hg while breathing room air; or (b) profound tissue hypoxemia measured by mixed venous Pao2 and suggested by symptoms such as cor pulmonale and congestive heart failure; or (c) pulmonary hypertension or polycythemia even though daytime Pao2 is greater than 55 mm Hg. Arterial blood must be obtained to demonstrate hypoxemia and assess the benefits of oxygen therapy. Patients on chronic oxygen must remain under close medical supervision. There are no absolute contraindications to chronic oxygen therapy, other than refusal of the patient to quit smoking. Complications of therapy appear to be negligible. The exciting suggestion of improved prognosis in patients with chronic obstructive lung disease on oxygen therapy and the possibility of delaying the long-term sequelae of chronic respiratory failure bear careful watching in the future.

Acidosis, Respiratory↗
PubMed1977

Thyroid radiation dose during panoramic and cephalometric dental x-ray examinations.

Radiation exposure from panoramic equipment can be reduced significantly by use of smaller film, adjustment of the beam height to the height of the smaller film, and careful positioning of patients. These techniques have no adverse effect on the quality of the diagnostic information needed in dentistry. In addition to describing methods of reducing exposures from panoramic machines, this study demonstrates that the use of a barrier collar during static, cephalometric examinations can appreciably reduce thyroid exposure. Since the objective is to obtain diagnostic information from the film without irradiating the thyroid, the application of a lead-impregnated collar is a minor inconvenience, easily borne by the patient and operator. It should be noted that the use of the collar during panoramic examinations affords little or no protection since the relative motion of the panoramic machine places the axis of movement inside the head and neck of the patient. While the evolution of diagnostic radiology may have reached a high level of technical refinement of equipment and film the clinician still must avoid unnecessary exposure for X-ray examinations and must carefully select the best type of examination to be used for each patient. For example, a complete panoramic examination to determine the position of a known unerupted third molar tooth is probably not an exercise of good judgment since other examinations, such as periapical, could yield the same information with less exposure. Decisions must be made with good judgment, value being placed on relative risks versus the benefits of diagnostic yield.

Adolescent↗