News - Part 65

Training in Laser Bronchoscopy and Proposals for Credentialling (Part 2)

A similar situation exists at the present time as it pertains to training in laser bronchoscopy. The methods of dealing with the demand for training are very much like what was observed for fiberoptic bronchoscopy; physicians have a desire to learn a new technique after they have already completed formal training in a residency or fellowship program. Gradually, this will become a “non-issue,” as laser bronchoscopy becomes an integral part of many (but probably not all) approved residencies in pulmonary diseases, thoracic surgery, and otorhinolaryngology. When considering the issue of training in laser bronchoscopy, it may help to see how physicians who had already completed their formal training years dealt with their needs/desires to learn how to use the fiberoptic bronchoscope. ventolin inhalers Read more »

Training in Laser Bronchoscopy and Proposals for Credentialling (Part 1)

Training in Laser Bronchoscopy and Proposals for Credentialling (Part 1)Surgical techniques are usually learned during the course of a formal residency or fellowship program in a particular discipline. However, from time-to-time, a new technique is devised which is of significant interest to physicians who have already completed their formal training, and of potential benefit to a number of patients, that the technique “catches on” and is applied in daily practice. Such a phenomenon occurred in the late 1960s and early 1970s after the pioneering work of the Japanese to invent fiberoptic bronchoscopes. Before that, rigid bronchoscopy was largely within the domain of thoracic surgeons, oto-rhinolaryngologists, and a few bronchoesophagolo-gists. Then, after fiberoptic bronchoscopes became available, large numbers of pulmonary physicians and other specialists expressed a desire to learn how to use this new instrument. The problem arose as to how they might best learn. ventolin inhaler Read more »

Sleeping and Breathing: REM Atonia Compromises Rib Cage Inspiratory Muscles

Sleeping and Breathing: REM Atonia Compromises Rib Cage Inspiratory MusclesRib cage inspiratory muscles (external intercostal, parasternal, scalene and sternocleidomastoid) contribute to a minor extent to normal breathing in adult males. Accordingly, loss of their action during REM sleep is compatible with maintenance of a normal alveolar ventilation during this stage of sleep, particularly in view of associated reduction in metabolic rate. This situation is drastically altered in diseases such as diaphragm paralysis or COPD. In the latter, changes in diaphragm configuration greatly compromise its pressure-generating capability. Read more »

Sleeping and Breathing: Sleep Modifies Chemical Control of Breathing (Part 2)

The shift from wakefulness to non-REM sleep is not without effect on chemical control of breathing, however. A dramatic effect appears when chemical stimuli are reduced rather than increased. With mechanically assisted hyperventilation or with hyperventilation induced by hypoxic stimulation of breathing, the respiratory efforts are eliminated when arterial Pco2 decreases 2-4 mm Hg. Although difficult to measure directly, a 10-20 mm Hg decrease is required in awake man. This difference can be depicted on the motor output/Pco2 relationship shown in Figure 2; during wakefulness, the curve has a “hockey-stick” shape, with the bend lying near the eupneic point. During REM sleep, no steep decline occurs in the motor output when arterial Pco2 declines below the eupneic level. Read more »

Sleeping and Breathing: Sleep Modifies Chemical Control of Breathing (Part 1)

Studies in man have revealed alveolar hypoventilation and diminution of ventilatory responsiveness to chemical stimuli during non-REM sleep, while results in tracheostomized dogs and intact cats reveal little alteration in alveolar ventilation and chemoventilatory responsiveness. Demonstration that upper airway resistance rises dramatically during sleep has led to the speculation that ventilatory responsiveness declines in man owing to the added resistive load, as described above. Read more »

Sleeping and Breathing: Sleep Removes Wakeful Motor Compensations (Part 2)

Sleeping and Breathing: Sleep Removes Wakeful Motor Compensations (Part 2)Patients with primary abnormalities of the respiratory pump, eg, restrictive chest wall or neuromuscular affecting the respiratory muscles, provide similar lessons to the observant physician. Alveolar ventilation during the day is normal in early stages of such diseases. However, during non-REM sleep, alveolar ventilation declines and arterial blood gas values deteriorate. This manifests wakefulness-dependent influences descending probably onto the bulbar respiratory network acting to augment the motor output of inspiratory and/or expiratory bulbospinal neurons. Read more »

Sleeping and Breathing: Sleep Removes Wakeful Motor Compensations (Part 1)

An obvious example of an anatomic abnormality causing sleep disordered breathing is obstructive sleep apnea caused by micrognathia. When the patient is awake, the pharyngeal airway is patent, but with sleep onset it occludes. We can infer, therefore, that wakefulness provides enhanced motor activation of upper airway muscles, which compensates for the tendency of a short mandible to close the pharyngeal airway. This motor compensation involves the neurons of the upper airway premotor network and undoubtedly involves higher neural “centers.” Read more »

Sleeping and Breathing: The Respiratory Controller

A basic view of the neural mechanisms controlling breathing is provided in Figure 1. The notion of a respiratory central pattern generator, essentially a timer that paces the rhythm, now enjoys wide acceptance but limited experimental proof.2 According to this concept, the output of this generator somehow gates the activity of neuronal networks that shape the inspiratory burst producing ramp-like activity for bulbospinal neurons and a square wave pattern for “upper airway motoneurons.” Read more »

Sleeping and Breathing (Part 2)

Breathing, the quintessential interaction between the organism and its environment, must continue when all other such interactions have ceased. As might be expected, this is not always successfully accomplished. Despite complex neural machinery automatically controlling the motor act of breathing, many individuals sustain respiratory failure during sleep. The present communication reviews how sleep and interact such that sleep disorders breathing, disordered breathing disturbs sleep, disturbed sleep further disorders breathing, and so on. Read more »

Sleeping and Breathing (Part 1)

Sleeping and Breathing (Part 1)In Night Thoughts of a Classical Physicist, McCormack portrays a beleagered 19th century physicist struggling to cope with revolutionary advances in physics. The “ether” theory of light has been replaced by the daunting mathematics of quantum mechanics, and the insomniac scientist broods through the night about the fundamental nature of light as inferred from its global behavior. The nocturnal respiratory physiologist, studying breathing during sleep, also struggles to infer basic mechanisms from global behavior. He seeks to better understand respiratory control by observing changes in stimulus-response characteristics when sleep replaces wakefulness. These “night thoughts” are the broodings of a “classical” physiologist to understand a complex system from rather simple observations at the bedside. Doubtless, real progress will require more sophistication; nonetheless, these night thoughts have been amusing and revealing. buy flovent inhaler Read more »

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