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Biomedical subjects

A J Block

Publications and source records attributed to A J Block.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1977

Effect of ultrasonic nebulization on arterial oxygen saturation in chronic obstructive pulmonary disease.

Twenty patients with mild to severe chronic obstructive pulmonary disease received ultrasonic nebulization to assess the danger of short-term changes in blood gas levels during this therapy. The status of arterial oxygenation was monitored during 20 minutes of therapy and for 20 minutes following therapy. In nine patients with periodic studies of arterial blood, the mean change in arterial oxygen pressure from base line was a decrease of 0.8 mm Hg at ten minutes into therapy, 2.8 mm Hg at the conclusion of therapy, and 2.9 mm Hg 20 minutes after therapy. In all 20 patients, ear oximetric studies showed only a small mean change at ten minutes into therapy, at the end of therapy, and at 20 minutes after therapy. Changes in the status of arterial oxygenation during and after therapy with ultrasonic nebulization in a group of patients with chronic obstructive pulmonary disease are generally small and of no statistical and limited clinical significance; however, alarming falls in arterial oxygenation can occur and cannot be predicted by base-line testing of pulmonary function or studies of arterial blood. It would be prudent to monitor patients with chronic obstructive pulmonary disease during therapy with ultrasonic nebulization or to withhold therapy altogether.

Adult↗
PubMed1977

Amyotrophic lateral sclerosis presenting with respiratory failure. Diaphragmatic paralysis and dependence on mechanical ventilation in two patients.

Described are two patients whose initial symptom was acute respiratory failure requiring mechanical ventilation. Initially, the cause of the respiratory failure in each patient was obscure, but diaphragmatic paralysis was subsequently demonstrated fluoroscopically in each case. Further neurologic evaluation then supported the diagnosis of amyotrophic lateral sclerosis. Postmortem examination corroborated this diagnosis.

Aged↗
PubMed1977

Prospective evaluation for pneumonectomy using the 99mtechnetium quantitative perfusion lung scan.

We evaluated 33 high-risk patients before pneumonectomy, all of whom had a forced expiratory volume in one second (FEV1) of less than 2.0 L before surgery. A quantitative perfusion lung scan was used to assess the right-left distribution of blood flow. A predicted postoperative FEV1 was calculated from the information on the lung scan and the preoperative FEV1. If this calculated value exceeded 800 ml, the patient was physiologically cleared for surgery up to and including a pneumonectomy. Surgery was otherwise believed to be contraindicated in the absence of studies using balloon occlusion. Perioperative mortality (less than or equal to 30 days after surgery) was found to be 15 percent (5/33). In surgery of this magnitude, we find this to be an acceptable percentage of mortality and have continued to use these simple physiologic criteria to determine whether a patient can tolerate pneumonectomy.

Aged↗
PubMed1977

Neuropsychologic effects of continuous oxygen therapy in the aged.

This study investigated the effects of continuous therapy with oxygen on the neuropsychologic functioning of aged subjects professing problems with their memory. Nineteen men (mean age, 71 years) were evaluated on eight neuropsychologic measures during three different periods of time. Subjects were tested before any treatment, after a month of continuous therapy with oxygen, and after a period of sham treatment. The results indicated statistically significant improvement in the Wechsler Memory Quotient and, with one exception, improvement in all other measurements in favor of the treatment with oxygen. Differences between the results of this investigation and those of other studies are discussed, along with the factors possibly accounting for these differences.

Aged↗
PubMed1977

Continuous in-vivo monitoring of arterial oxygenation in chronic obstructive lung disease.

We monitored arterial oxygen saturation (SaO2) in 10 patients with severe chronic obstructive lung disease during 24 h of breathing room air followed by 24 h of breathing two litres of oxygen per minute. Three subjects without chronic obstructive lung disease were monitored while breathing room air. Greatest declines in SaO2 occurred during sleep, with intermittent decreases as great as 44% saturation (range, 12% to 44% saturation. Baseline SaO2 was significantly higher while patients breathed low-flow oxygen (94% versus 86% saturated), and declines in SaO2 during sleep were less noteworthy (1% to 27% saturation). Subjects without chronic obstructive lung disease showed declines in SaO2 of much lesser magnitude (3% to 11% saturation) with sleep. These declines were not primarily due to alveolar hypoventilation. Our data indicate that there are patients with chronic airways obstruction who suffer profound intermittent desaturation at night that can readily be relieved with low-flow oxygen administration.

Aged↗
PubMed1976

Effects of halothane on pulmonary inactivation of noradrenaline and prostaglandin E2 in anaesthetized dogs.

1. The inactivation of noradrenaline and prostaglandin E2 was studied in the pulmonary circulation of anaesthetized dogs. 2. Under chloralose anaesthesia and ventilation with air, the inactivation of noradrenaline was 20% and that of prostaglandin E2 was 91%. These values are in agreement with results from previous work. 3. When the dogs were ventilated with halothane-air mixtures, the inactivation of prostaglandin E2 was unaffected but that of noradrenaline was significantly reduced. 4. This effect of halothane is probably due to an interaction with the transport system for noradrenaline associated with cell membranes. 5. Analogous changes in pulmonary noradrenaline inactivation could occur in patients anaesthetized with halothane.

Animals↗
PubMed1976

Acute respiratory failure precipitated by a carbonic anhydrase inhibitor.

A 60-year-old white man with chronic bronchitis was noted to develop acute respiratory failure and metabolic acidosis four days after being started on methazolamide (Neptazane) for an ophthalmologic problem. The patient was intubated with ventilator support and improved after his metabolic acidosis resolved. Caution is emphasized in the use of carbonic anhydrase inhibitors in patients with obstructive airway disease.

Acidosis, Respiratory↗