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Biomedical subjects

M Kryger

Publications and source records attributed to M Kryger.

11 recordsLinked to original sources
PubMed1992

The importance of nasal resistance in obstructive sleep apnea syndrome.

The importance of nasal airflow resistance in the pathogenesis of obstructive sleep apnea syndrome (OSAS) remains contentious. We performed formal nocturnal polysomnography (PSG) on OSAS patients under conditions of baseline and reduced nasal resistance to answer two main questions. First, to what degree does baseline nasal airflow resistance influence upper airway collapse in OSAS patients? Second, in what proportion of the OSAS population is baseline nasal resistance contributing to the pathogenesis of upper airway collapse? Our study group consisted of 10 patients with a wide range of OSAS severity. Six of these patients had symptoms and clinical evidence of chronic nasal obstruction which, in some, was associated with markedly elevated nasal resistance. A placebo (normal saline) was instilled in the nose of each patient on the night of baseline data collection. On the treatment night of the study, nasal resistance was reduced by application of topical vasoconstrictor and insertion of vestibular stents designed to dilate the area of the nasal valve. Posterior rhinomanometry was used to measure resistance to nasal airflow immediately before and after each PSG study. Although treatment was associated with a subjective improvement in sleep quality and mean drop in nasal resistance of 73% (P less than 0.001), there was no significant improvement in sleep architecture, nocturnal oxygenation, or the amount of apnea experienced by patients. The most significant improvement was a reduced number of arousals/hour from 52.4 +/- 12.4 on placebo to 43.7 +/- 10.2 on treatment (P less than 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1978

Impaired oxygenation during sleep in excessive polycythemia of high altitude: improvement with respiratory stimulation.

Although polycythemia of high altitude is usually due to excessive hypoxemia, in some patients the hematocrit is elevated out of proportion to the degree of hypoxemia measured awake. One possible explanation is that severe hypoxemia occurs during sleep in these subjects. We therefore monitored oxygen saturation (SaO2), breathing pattern, and electroencephalogram (EEG) during sleep in five normal high-altitude residents and in five patients with excessive polycythemia. The polycythemic patients were studied as part of a placebo--drug double-blind crossover trial of the respiratory stimulant drug medroxyprogesterone acetate (MPA). The polycythemic patients while taking placebo were much more hypoxemic during sleep than the normals (all-night mean SaO2: 79.4 +/- 1.7% versus 87.8 +/- 1.7%, p less than 0.01). Abnormalities in breathing patterns were observed in all the subjects, especially during REM stage sleep. In polycythemic subjects, this resulted in precipitous hypoxemia with SaO2 as low as 50%--70%. Severe hypoxemia was not observed in control subjects despite similar abnormalities in breathing. Significant improvement in nocturnal SaO2 occurred when the polycythemic patients were taking MPA, mean SaO2 rising from 79.4 +/- 1.7% to 83.7 +/- 0.7%, p less than 0.05. Of probably greater importance, MPA largely prevented the precipitous drops in SaO2, mean lowest SaO2 rising from 64.6 +/- 4.7% to 76.0 +/- 2.1% p less than 0.05. The severe decreases in SaO2 during sleep may explain elevations in hematocrit that are out of proportion to the awake SaO2 in man at high altitude. The therapeutic effect of MPA in this condition may be due to amelioration of sleep hypoxemia.

Adult↗
PubMed1978

Diagnosis of airflow obstruction at high altitude.

Using predicted sea level values for spirometry done at high altitude, underestimation of airway obstruction may result. We therefore established spirometric normal values for an altitude of 3,100 m for white men.

Adolescent↗
PubMed1978

Excessive polycythemia of high altitude: role of ventilatory drive and lung disease.

Persons residing at high altitude who develop excessive polycythemia are more hypoxemic than normal high-altitude residents. We investigated the causes of hypoxemia in 20 patients with excessive polycythemia residing at an altitude of 3,100 m. Lung disease evidenced by abnormal spirometric features and results of a respiratory questionnaire was present in 10 of 20 patients and resulted in increased alveolar-arterial difference for PO2 [(A-a)PO2]. The excessive hypoxemia in the patients with normal lungs was not due to increased (A-a)PO2. We measured ventilatory responses to hypoxia and to hypercapnia to determine whether blunting of these responses was a cause of this excessive hypoxemia. We found, however, that chemical drives to breathe, although blunted, were the same in patients with polycythemia as in high-altitude control subjects. However, an abnormal breathing pattern was observed; the polycythemic patients had a smaller tidal volume and a greater ratio of dead space to tidal volume than did the normal subjects. In addition, the polycythemic patients had increased minute ventilation on breathing 100 percent O2, whereas the normal subjects did not. Thus, hypoxic depression of ventilation may have been present. Our findings suggested that blunted chemical drives are not causative in this disease, and that some other cause of hypoxemia must be present.

Altitude↗
PubMed1977

Case report.

Explore the source record for details and available documents.

Adenoma↗
PubMed1976

Clinical semi-starvation: depression of hypoxic ventilatory response.

A decreased metabolic rate has been associated with decreased ventilatory response to hypoxia and hypercapnia, and also with starvation. We fed a 500-calorie carbohydrate diet with supplemental electrolytes, designed to simulate alimentation by usual intravenous fluids, to seven normal subjects for 10 days to determine the effect of semi-starvation on metabolic rate and ventilatory responses. By the 10th day metabolic rate was significantly decreased, and hypoxic ventilatory response decreased to 42% of control (P less than 0.05). In two subjects, hypoxic ventilatory response was virtually abolished at day 10. These changes reversed toward normal with refeeding. The decrease in hypoxic ventilatory response response was significantly (P less than 0.01) related to the decrease in metabolic rate. Hypercapnic ventilatory response, measured as the slope of the ventilatory response to hypercapnia, decreased slightly but not significantly. The decrease in hypoxic ventilatory response seen during semi-starvation may contribute to the hypoxemia and respiratory failure subsequent to caloric restriction.

Adult↗
PubMed1976

Diagnosis of obstruction of the upper and central airways.

Patients with obstruction of the upper airways are often treated for long periods of time for other disorders. Correct diagnosis is important since treatment is quite specific. Such patients may present with a characteristic history and findings on physical examination. Certain physiologic tests such as flow-volume loops with and without helium help to prove the diagnosis. Patients with upper airway obstruction may also have sleep apneas and the sleep deprivation syndrome. Methods of diagnosis of upper airway obstruction are presented and three instructive cases are reviewed.

Airway Obstruction↗