[Pathophysiology of dyspnea]. / Pathophysiologie der Dyspnoe.

The sensation of dyspnea is related to pathologically increased breathing work as a result of hyperventilation and/or increased airway resistance. Low cardiac output resulting in tissue hypoxia provokes hyperventilation. In diffuse interstitial lung diseases, hyperventilation is combined with severely reduced lung compliance. In severe airway obstruction, hypoventilation is the result of excessively enhanced breathing work. Habituation and acute changes of situation have an important bearing on the subjective sensation of dyspnea.

[Decompression problems in diving in mountain lakes]. / Dekompressionsprobleme beim Bergseetauchen.

The relationship between tolerated high-pressure tissue nitrogen and ambient pressure is practically linear. The tolerated nitrogen high pressure decreases at altitude, as the ambient pressure is lower. Additionally, tissues with short nitrogen half-times have a higher tolerance than tissues which retain nitrogen for longer duration. For the purpose of determining safe decompression routines, the human body can be regarded as consisting of 16 compartments with half-times from 4 to 635 minutes for nitrogen. The coefficients for calculation of the tolerated nitrogen-high pressure in the tissues can be deduced directly from the half-times for nitrogen. We show as application the results of 573 simulated air dives in the pressure-chamber and 544 real dives in mountain lakes in Switzerland (1400-2600 m above sea level) and in Lake Titicaca (3800 m above sea level). They are in accordance with the computed limits of tolerance.

[Incidents in sports diving]. / Zwischenfälle beim Sporttauchen.

Barotrauma of the ear is the most frequent incident in sport-diving. In some cases, inner ear disorders appear. Barotrauma with rupture of the lung can provoke gas embolism into the central nervous system and unconsciousness. Gas embolism into the spinal cord and decompression sickness of the spinal cord provoke practically the same neurological disturbances. The lower half of the body is mostly affected. Drowning in sport-diving is mostly the result of loss of consciousness resulting from hypoxia or hyperoxia, nitrogen-narcosis or gas embolism into the brain. Inner ear disorders, gas embolism in the brain or the spinal cord, decompression sickness of the spinal cord or the muscles and joints require treatment in the pressure chamber with hyperbaric oxygen. This treatment remains effective even if started some days after the dive.

[Computation of low-risk compression. Computation model and results of experimental decompression research]. / Die Berechnung der risikoarmen Dekompression. Rechenmodell und Ergebnis der experimentellen Dekompressionsforschung.

1. The relationship between tolerated nitrogen oversaturation and ambient pressure is practically linear. 2. Tissues with short half-times have a higher tolerance than tissues with long half-times. 3. The human body can be regarded as consisting of 16 compartments with half-times from 4 to 635 minutes for nitrogen and from 1.5 to 240 minutes for helium. 4. The coefficients for calculation of minimal tolerated ambient pressure for a given PN2 in the tissue can be deduced directly from the half-times for nitrogen. 5. The results of 573 simulated air dives and 544 real dives in mountain lakes are in accordance with the computed limits of tolerance. 6. The ZH-L16 system is applicable to all exposures with air or oxygen-nitrogen mixtures. 7. Adaptation to breathing of oxy-helium or trimix is simple.

Decompression after repeated dives.

Seventy-six men and 7 women performed a 2nd dive in a pressure chamber under dry conditions after intervals at the surface of 10, 30, 90, or 120 min. Of these, 35 persons performed a 3rd dive after an interval of 20 or 90 min (118 repeated dives). Air was the breathing gas during all phases of the tests. During exposure to overpressure the divers exercised on a bicycle-ergometer. The decompressions for dives 2 and 3 were the same as for the first dive. After the 2nd or 3rd dive, certain symptoms of decompression sickness of the skin occurred in 5 of the 118 exposures, and 1 diver complained of muscular aches. These results suggest that no general sensitization occurred after the 1st dive. We concluded that a slightly more conservative decompression with regard to ascent velocity and profile is feasible for repeated dives.

[Decompression sickness of the spinal cord. Results of early and of late treatment]. / Dekompressionskrankheit des Rückenmarks. Resultate der Früh-und Spätbehandlung.

The treatment of 20 scuba divers with decompression sickness of the spinal cord between 1969 and 1984 is reported. Seven patients presented with mild sensomotor impairments, 13 patients were paraplegic and some suffered from additional impairments to the arms. In 12 of the divers the accident that occurred in a Swiss lake and recompression was initiated with a latency of a few hours. These early treatments were successful in 11 patients. The neurologic symptoms already improved during recompression even in the 7 patients who were paraplegic. In a paraplegic woman early treatment failed, but her condition improved under subsequent hyperbaric oxygen treatment. In 9 patients late treatment after an interval of 48 to 192 hours, consisting of repeated hyperbaric oxygen exposures, was performed. 3 patients with mild neurologic disturbances improved completely. 6 patients were paraplegic. In 5 of these early treatment was without success. On 3 occasions, however, early treatment was not started before 15 to 24 hours after the dive. All 6 paraplegic patients improved considerably during late treatment. 8 of the 9 patients undergoing hyperbaric oxygen treatment had been transported by air with slightly reduced cabin pressure from the foreign country to Zurich. No deterioration of neurologic symptoms was observed during air transport.

[Stomach rupture while diving]. / Magenruptur beim Tauchen.

A case of stomach rupture in a 47-year-old scuba diver is reported. Symptoms of gastrointestinal expansion during ascent are quite common and are caused by decompression of swallowed air. Gastric perforation is however rare, and needs to be promptly recognized and surgically repaired.

[Pathophysiology of pulmonary embolism]. / Lungenembolie, Pathophysiologie.

Massive pulmonary embolism causes an acute pressure overload for the right ventricle associated with a drop in cardiac output leading, if untreated, to cardiogenic shock. Main symptoms of acute pulmonary embolism comprise dyspnea, hyperventilation, tachycardia, hypotension and cyanosis, which are the consequences of tissue hypoxia caused by hypoperfusion. Mild to moderate arterial hypoxemia, which is observed in most of the cases, can be explained by intrapulmonary venous admixture.

[Reactivity of the bronchi in pollen rhinitis and pollen asthma the before and during the pollen season]. / Reagibilität der Bronchien bei Rhinitis pollinosa und Asthma pollinosum vor und während der Pollensaison.

Nonspecific bronchial reactivity was investigated during and out of the pollen season in 28 pollen-allergic asthmatics and 25 hay fever patients without bronchial asthma. The degree of the reactivity was measured by the decrease of inspiratory specific airway conductance (sGI) after voluntary hyperventilation. Before hyperventilation the mean values for the sGI in both groups of patients were within the low normal range and revealed no seasonal fluctuations. During the pollen season 26 (93%) asthmatics and 14 (56%) hay fever patients showed bronchial hyperreactivity. Out of season 22 (79%) asthmatics and only 8 (32%) hay fever patients were hyperreactive. Thus, in the absence of the relevant allergens, most of the pollen sensitive asthmatics showed a significant increase in unspecific bronchial reactivity which was somewhat higher during the pollen season. The seasonal increase of bronchial reactivity in hay fever patients suggests a relationship with pollen asthma. 12 pollen-allergic asthmatics, who were examined again in the next pollen season after one period of preseasonal specific hyposensitization with pollen extracts, displayed a significant decrease in nonspecific bronchial reactivity.

[Decompression during lowered air pressure]. / Untersuchungen zur Dekompression bei erniedrigtem Luftdruck.

A linear relationship exists between the overpressure of inert gases in the tissues which is tolerated without symptoms, and the ambient pressure in the range between 1.0 and 50.0 bar. Sixteen subjects, all residents at normal atmospheric pressure and saturated with a nitrogen pressure of 0.75 bar, were decompressed to an ambient pressure of 0.47 bar (corresponding to an altitude of 6000 m above sea level) in 15 minutes. During a 3 hours' stay at this pressure breathing air, symptoms of hypoxia developed but not arthralgias. After hyperbaric exposures in the range between 4.0 and 5.1 bar breathing air, 103 subjects were decompressed and exposed to an ambient pressure between 0.60 and 0.85 bar after surface intervals of varying duration. In 31 of the 103 subjects, the ambient pressure was more reduced than according to the tolerated linear relation. 7 of these 31 subjects reported light pain in the shoulders of knees during the 2 hours' stay at the reduced ambient pressure. These trials demonstrate that the linear relationship between the ambient pressure and the overpressure of inert gas in the tissues tolerated without symptoms is also valid at altitude.

[Magnesium oxide as cause of metal fume fever]. / Magnesiumoxid als Ursache des Metallrauchfiebers.

Seven foundry workers are described who all developed pulmonary symptoms and in the majority of cases recurrent occupational fever; the onset of these episodes coincided with the introduction of a new founding technique resulting in exposure to magnesium oxide fumes. The foreman - most exposed because responsible for vaccination of the melted iron with metallic magnesium - developed disabling pneumopathy. The feverish episodes are interpreted as metal fume fever and in 6 patients the pneumopathy is considered to be due to alkalitoxic damage to the small airways and alveoli caused by the magnesium oxide fumes. The seventh patient suffered from allergic asthma bronchiale. Differentiation from hypersensitivity pneumonitis and from humidifier fever of nonallergic etiology is discussed.

[Effect of regular training on total and vital capacity of the lung in 17 to 25-year-old rowers]. / Der Einfluss eines regelmässigen Trainings auf Total- und Vitalkapazität der Lunge bei 17-25jährigen Ruderern.

Lung volumes, FEV1 and airway resistance have been repeatedly measured from age 17 to 26 in a group of 16 rowers. Total capacity, vital capacity and FEV1 are in the upper normal range. Airway resistance is normal. The increase in total and vital capacity from age 17 to 26 has been within the normal limits of other young men in the same age group. Intensive training does not appear to influence total and vital capacity once the final height has been reached. Top Swiss rowers of the years 1981 and 1982 have total and vital capacity values well above the predicted values for men of the same height and age, and also above those measured in top Swiss rowers of the period 1968-1972. The latter finding can be explained by a difference in the selection process.

[Reactivity of the respiratory tract in healthy humans and with beta-adrenergic blockade]. / Reagibilität der Atemwege bei Gesunden unter beta-adrenerger Blockade.

Airway resistance, FEV 1.0 and lung volumes were measured in 11 normal subjects before and after voluntary hyperventilation and after inhalation of salbutamol and hyperventilation. The measurements were repeated the following day two hours after taking 40 mg propranolol. Under propranolol there is only a minimal increase in inspiratory and expiratory resistance and no change in bronchoconstriction induced by hyperventilation, but the spasmolytic effect of salbutamol is reduced. Blockade of beta-receptors is without influence on airway irritability in subjects without bronchial asthma or chronic asthmatic bronchitis. Blockade of beta-receptors can however reduce the effect of beta-2-receptor stimulants.

[Oxygen consumption of the respiratory muscles in increased respiratory resistance]. / Sauerstoffverbrauch der Atemmuskulatur bei erhöhten Atemwegwiderständen.

The alveolar pressure was measured in 15 healthy men at different flow rates breathing without and with additional resistance from a stenosis (diameter 7 mm). Ventilation, breathing frequency, pulse rate, O2-uptake, and CO2-elimination were also measured during rest and during bicycle exercise. At rest, FRC and gas exchange were unaltered, while ventilation and breathing frequency little with the additional resistance. During work, however, the stenosis, caused increased O2-uptake and CO2-elimination and decreased ventilation and breathing frequency. The mean O2-consumption by the respiratory musculature necessary to overcome the airway resistance is 0.00042 ml/gcm.

[Lung volume and airway resistance in healthy schoolchildren in Zurich--normal values]. / Lungenvolumina und Atemwegwiderstände bei gesunden Zürcher Schulkindern--Normalwerte.

Total- and vital capacity (TC, VC), FIV1, FEV1 and airway resistance were determined in 45 boys and 44 girls aged 8 to 12 years with the aid of body-plethysmography. 2. VC correlates best with body height. Boys have a 200 ml greater VC than girls. Beginning with 12 to 13 years, age is an additional factor modifying VC. 3. The ratio VC/TC averages 0.835 in boys and 0.824 in girls, the ratio is independent of the VC. 4. Airway resistance is appreciably higher than in adults and decreases with rising VC and body growth. 5. FIV1 is 87%, FEV1 is 80% of VC. These values are independent of sex and VC.