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PubMed1981

Influence of respiration on stroke volume determined by impedance cardiography.

The conventional method of calculating stroke volume (SV) with impedance has been to measure changes in thoracic impedance for only those beats of the impedance cardiogram (IC) which cross on a specific baseline. This severely limits the number of usable beats since respiration produces oscillation of the IC around this baseline. This study investigated the influence of respiration on SV calculated independent of the baseline in seven women, 20-44 years old, in each of three postures: seated, supine, and standing. SV was determined in three continuous respiratory cycles from the following beats: 1. all; 2. all inspiratory (I); 3. I on baseline; 4. all expiratory (E); 5. E on baseline; 6. all end-E; 7. end-E on baseline (conventional). The absolute values for SV, heart rate (HR), and cardiac output (Q) were posture dependent. SVs did not differ among the respiratory phases in the standing and seated postures; in the supine posture, the smallest SV occurred at end-E on baseline. HR varied with respiration in both the standing and seated postures but not in the supine posture. Despite significant changes in HR in the seated and standing postures, Qs did not differ among the respiratory phases. Supine Qs were significantly smaller during end-E due primarily to a small SV. Consequently, when reporting Q values for supine subjects, it is important to designate the respiratory phase and baseline criteria. Our results indicate that SVs calculated independent of the baseline in general agree with the more conventional method of calculation. Therefore, we recommend the calculation of SV independent of the baseline. The reliability of the data will be increased by increasing the number of observations and SVs can be determined under circumstances where it is difficult to obtain end-E beats on the baseline.

Adult↗
PubMed1981

[Death by obstructive asphyxia: the pathophysiology of respiration and hemodynamics (author's transl)].

The pathophysiology of respiration and hemodynamics during the agonal period of death by obstructive asphyxia was investigated. Experiments were carried out on ten dogs that were strangulated by ligature (seven cases) or asphyxiated by occlusion of the intubation tube (three cases). The following parameters were registered: Blood pressure in the arteria femoralis and arteria pulmonalis, electrocardiogram, endotracheal pressure, respiratory frequency, electroencephalogram. These were the most important findings: (a) An excessive and distinctly biphasic hypertonic reaction takes place after strangulation by ligature whereas occlusion of the intubation tube results in a slight increase of arterial blood pressure. (b) After occlusion of the tube more than after strangulation the endotracheal pressure becomes deeply negative during the inspiration trials. (c) After cessation of respiration a distinct pulmonary arterial hypertension develops in both forms of obstructive asphyxia. (d) The paralysis of the respiratory center takes place after about 4 min at the same time when the circulatory breakdown develops. The final cardiac failure occurs after about 9-10 min. The dysregulation of respiration and hemodynamics in the agony of obstructive asphyxia can be differentiated from other shock models. This results in special morphological alterations of the lung tissue which have been described elsewhere.

Airway Obstruction↗
PubMed1980

The relationship between respiration, pressure and flow distribution in the vena cava and portal and hepatic veins.

Factors affecting blood movement in the main vessels of the venous system and the changes in pressure and flow values in the vena cava and portal and hepatic veins were simultaneously recorded and related to the phases of the respiratory cycle. The experiments were done in rabbits subjected to nembutal anesthesia, with open abdomen, closed chest and spontaneous respiration. The results indicate an asymmetric pressure gradient in the vena cava centered around the diaphragm with larger pressure differences in the thoracic segment; no pressure gradient in the portal vein, and a sharp gradient of possible functional significance at the caval end of the hepatic veins. Portal, hepatic and abdominal caval pressures were positive, but above the diaphragm, vena cava pressure values were predominantly negative. Flow was continuous, unequally distributed throughout the components and fluctuating alternatively during one respiratory cycle. Maximal pressure and flow values in the portal and hepatic veins were concomitant with the lowest values in the vena cava and closely related to respiration. The distribution of opposite pressure and flow values within the components and their integration during one respiratory cycle suggest that, in the process of venous return, each component and each segment fulfills simultaneously different functions co-ordinated by respiration and cardiac activity.

Animals↗
PubMed1994

[Respiration and blood circulation in the terminal stages of deep hypothermia].

In immersion hypothermia (9 degrees C) the brain temperature was 2 degrees higher on the average than in the heart area and 3-4 degrees C higher than rectal temperature in rats. At the brain temperature below 24-25 degrees C a strong dependence of the respiration rate on the body temperature occurs followed by the same dependence for the heart rate and arterial pressure. Arrest of the respiration occurs at the brain temperature 18 degrees C on the average, heart arrest occurs within 31 min on the average (at the heart temperature 11 degrees C). The main hypothermic pathogenetic factor is a direct effect of the cold on the brain and heart added by hypoxia due to weakening and arrest of respiration.

Animals↗
PubMed1976

Function of external respiration after experimental lung autotransplantation.

The function of external respiration was studied by way of a dynamic observation of 15 animals whose course was uneventful following autotransplantation of the left lung. The longest follow-up period was 4 years. The following studies were conducted: spirography, bronchospirography, functional tests with the right (intact) lung excluded from respiration, bronchopneumotachygraphy, electromyography of the intercostal muscles, and analyses of blood gases and acid-base balance. During the early hours and days after left lung autotransplantation, hyperventilation and gas exchange decrease were observed in the operated lung, along with arterial and venous hypoxemia and signs of metabolic acidosis. With the right (intact) lung excluded and only the autograft breathing, a considerable reduction of oxygen saturation of the peripheral arterial blood was observed, which indicated the low compensatory capacity of the autotransplanted lung. Restoration and normalization of ventilation and gas exchange, blood gases, and acid-base balance were noted within 8 days after left lung autotransplantation. The compensatory capacity of the lung autograft, as shown by the test with the right (intact) lung excluded, was restored within the first 2 months after surgery. Following lung autotransplantation, in the absence of the Hering-Breuer reflex, the adaptative reactions of the external respiration apparatus are provided by the reflexes from the proprioreceptors of the breathing muscles of the thoracic wall and by humoral factors that acquire a leading role in the regulation of respiratory mechanisms. After removal of the right (intact) lung in the late postoperative period, the left lung autograft supports normal vital functions of the body (with the longest follow-up being 3 1/4 years). This convincingly proves that the organ's function and structure have been restored.

Acid-Base Equilibrium↗
PubMed1994

[Effects of vocalization and respiration and fiber connections on hyperstriatum ventrale pars caudale in Fringilla montifringilla].

In urethane-anesthetized Fringilla montifringilla, effects of electrically stimulating the hyperstriatum ventrale pars caudale (HVc) on vocalization and respiration were observed. Central connections of HVc were investigated by means of injecting CB-HRP into HVc. The results were as follows: (1) Electrical stimulation of HVc caused vocal response. (2) Long train electrical pulses stimulation of HVc elicited significant respiratory facilitating effects, that is, increase of respiratory rate and depth. (3) Short train stimulation administered in HVc during inspiratory phase terminated switching-off of inspiration, and during expiratory phases produced the prolongation of expiratory phase so to coordinate vocalization and then increasing the respiratory rate and depth. (4) CB-HRP traces revealed that HVc projected to robust nucleus of the archistriatum, and atea X of lobus parolfactorius. HVc received projections from medial nucleus magnocellularis of the anterior neostriatum, nucleus interfacialis of midneostriatum, telencephalic auditory nucleus-field L, nucleus uvaeformis of the thalamus, and locus ceruleus of the pons. These results showed that, besides vocal control, HVc may be involved in neural regulations of respiratory facilitation, the effect on respiration seeming specific. It is suggested that HVc may play an important role in coordinating singing and respiration.

Animals↗
PubMedDate not supplied

[Stereometric model of respiration with diaphragm electrostimulation].

A stereometric model of respiration has been proposed, which is based on the approximation of the surface of the chest and that of the diaphragm by the well-known mathematical functions, which generally calculates the value of respiratory volume as a function of geometric parameters such as the circumference of the chest and torso, the distance between the thoracic vertebrae. The derived formulas may be used as a background material for designing the feedback systems by the respiratory volume in order to maximally approach the electrically stimulated respiration to physiological respiration.

Diaphragm↗
PubMed1993

Role of respiration related units in the nucleus retrofacialis region in rats.

Experiments were carried out on 10 urethane anesthetized, spontaneously breathing rats. The distribution of respiration related units (RRUs) in the nucleus retrofacialis (NRF) region was explored systematically with an extracellular recording technique and their discharging patterns were analyzed through a microcomputer. A total of 212 spontaneously discharging units were recorded in the NRF region. Among them 120 were RRUs and the remainder were non-respiration related units (NRRUs). Among the RRUs, 28 were determined to be inspiration related units (InRUs); 81 were expiration related units (ExRUs) and 11 were phase-spanning respiration related units (PSUs) according to their temporal relation to phrenic activity. These RRUs were further classified into augmenting, decrementing and constant types based on their discharge patterns. The results indicated that RRUs in the NRF region were relatively abundant as compared to NRRUs, and they were more concentrated in the medial part of the NRF region (mNRF). Among them, ExRUs were predominant.

Animals↗
PubMed1993

[Spontaneous respiration versus IPPV in pigeons].

Veterinary textbook on anaesthesia in birds that volatile anaesthetics can accumulate in the air sac system during spontaneous respiration of birds anaesthetized with inhalational anaesthetics. In order to quantify the extent of accumulation, air samples were collected from the endotracheal tube and from the left abdominal air sac of ten pigeons anaesthetized with O2, NO2, and isoflurane. In this way, O2, CO2, and isoflurane concentrations were measured continuously at two places, during both spontaneous respiration and positive pressure ventilation. During spontaneous respiration, CO2-concentrations were higher in the air sac than in the endotracheal tube in 60% of the animals. The average difference for the whole group was 0.8 volume per cent; individual differences were as high as 2.9 volume per cent. The concentration of isoflurane was on average 1.1 volume per cent lower in the abdominal air sac than in the endotracheal tube. During mechanical ventilation, the percentage of CO2 was lower in the abdominal air sac than in the endotracheal tube in all pigeons. At the same time, the differences between isoflurane concentrations in the endotracheal tube and air sac decreased. Thus the results of our study with isoflurane-anaesthetized pigeons do not support the suggestion that volatile anaesthetics accumulate in the air sacs of spontaneously breathing birds anaesthetized with inhalation anaesthetics. The results also show that, under these conditions, CO2 concentrations in the endotracheal tube can only be measured reliably during positive pressure ventilation.

Air↗
PubMed1993

[Continuous monitoring of spontaneous postoperative respiration. 3. The effect of amiphenazole on cutaneous oxygen and carbon dioxide partial pressure following gynecologic surgery under halothane anesthesia].

METHODS: In an attempt to verify non-invasive respiratory monitoring for patients in the early postoperative period, cutaneous O2 and CO2 pressures were monitored in 30 female patients recovering from major gynaecologic surgery under halothane anaesthesia. In a double-blind and randomized fashion, in the recovery room the patients received a single intravenous bolus injection of placebo or 150 mg amiphenazole, a respiratory stimulant. The data were collected and stored in a personal computer, using the TCM3 system with a combination electrode for simultaneous measuring of cutaneous oxygen and carbon dioxide partial pressures (TINA, Radiometer) at 30-s intervals. The overall observation period was 240 min. Means and standard deviations were calculated for individual data and for data pooled at 15- or 60-min intervals. Groups were compared by means of the chi 2 test, Student's t-test, Wilcoxon rank sum test or analysis of variance (level of significance P < or = 0.05). RESULTS: The study groups were comparable with respect to demographic and anaesthesiological data. The partial pressures for both O2 and CO2 were not statistically significant between groups. Electrode heating was slightly higher with amiphenazole (n.s.), indicating a trend for peripheral vasodilation without a true improvement of spontaneous ventilation. pctO2 and pctCO2 levels were decreased or elevated, respectively, in the first observation hours and slowly returned to normal within the 240-min observation period. Episodes of hypercapnia (pct-CO2 > 50 or > 55 mm Hg) were frequent in the first 2 h (10-30% of individual data for pctCO2 > 50, 2-7% for pctCO2 > 55, respectively), indicating the need for close monitoring of spontaneous respiration after general anaesthesia with halothane. DISCUSSION AND CONCLUSION: The present study confirmed that spontaneous respiration in the early postoperative period can be monitored non-invasively by measuring transcutaneous partial pressures of carbon dioxide and, less precisely due to large individual variations, oxygen. It showed that spontaneous respiration deteriorates after gynaecological surgery under halothane anaesthesia and recovers slowly during the next 4 h. The respiratory stimulant amiphenazole (150 mg i.v.) was of no significant value with respect to the improvement of ventilation.

Adult↗
PubMed1993

Midazolam and flunitrazepam: pharmacokinetics and effects on night time respiration and body movements in the elderly.

In a double-blind crossover study, the pharmacokinetics and effects on night-time respiration and body movements of midazolam 7.5 mg, flunitrazepam 1 mg, and placebo were studied in 5 elderly insomniac patients with the static charge sensitive bed-method (SCSB). In a supine position, the gastrointestinal absorption rate of flunitrazepam (tmax 0.6 h) was faster than that of midazolam (tmax 0.95 h). The elimination phase half-life of midazolam was about twice as long as reported earlier in healthy adult volunteers, but ageing did not affect the elimination of flunitrazepam. The shape of the serum concentration-time curve of both benzodiazepine derivatives was quite similar. The sleep of these five insomniacs became more peaceful and the respiration more regular during midazolam and flunitrazepam, compared with placebo. Both benzodiazepines significantly decreased body movements and the cumulative movement time remained shorter throughout the night, compared with placebo. Total variability (VI) was clearly decreased with flurazepam, and a similar but not statistically significant tendency was seen with midazolam, compared with placebo. Accordingly, the proportion of quiet sleep (QS) increased (p = 0.014) and the proportion of active sleep (AS) decreased (p = 0.019) with both benzodiazepines, compared with placebo. This reflects the changed control of respiration by higher brain structures. No signs of increased respiratory resistance (i.e. ballistocardiographic respiratory amplitude variation BRV < 60%) were seen with either of the drugs or placebo. There were no differences in the subjects' own estimation of their sleep during medication with these drugs. Only the sleep onset latency was shorter with flunitrazepam compared with midazolam and placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1977

Magnitude of lead intake from respiration by normal man.

Lead metabolism of five normal men was studied in a hospital metabolic unit in order to measure the daily intake of lead by respiration in urban adults. Subjects ingested a constant diet, and samples of blood, urine, feces, and diet were analyzed periodically for lead isotopic abundances by mass spectrometry. Three men were fed daily a stable isotope tracer of lead for 83 to 124 days in order to distinguish ingested from respired lead. Also, three men lived in rooms with filtered, low-lead air for 25 to 50 days in order to examine the response of blood lead levels to a change in airborne lead exposure. The quantity of respired lead intake was determined from the lead balance data, labeling of blood lead with a dietary lead tracer, and the response of blood lead levels and lead balances to exposure to low-lead air. The results indicate that these men absorbed a mean of 14 +/- 4 (S.D.) microgram/day of lead while exposed to the ambient levels of about 2 microgram/m3 of airborne lead. About twice this amount was absorbed from the diet.

Air↗
PubMed1977

[Regulation of respiration at high altitudes and its molecular interpretation: the sequence of beta-chains of hemoglobins from pig and llama (author's transl)].

The primary structures of the beta-chains from pig (Suidae) and llama (Lama glama, Camelidae) hemoglobins are given. They differ from human beta-chains in the exchange of 22 and 23 amino acid residues, respectively. Some aspects of the sequences are discussed and the molecular interpretation of respiration at high altitudes is given. This interpretation is based on the exchange of the 2,3-diphosphoglycerate contact beta2His leads to Asn from man to llama: the interaction between the heterotropic allosteric effector 2,3-diphosphoglycerate and protein is diminished, which results in higher oxygen affinity of the hemoglobin of llama. Thus the placental respiration and the high-altitudes respiration have the same molecular mechanism.

Altitude↗
PubMed1996

Influence of respiration on human sympathetic skin response.

Sympathetic skin response (SSR) is a reflexly elicited potential of the sweat glands, the afferent and efferent fibres of the reflex are cutaneous sensory fibres (if the SSR is elicited by electrical stimulus) and sympathetic sudomotor fibres respectively. Our earlier study indicated that latency, besides duration and amplitude, of SSR of a given normal individual showed significant variations between many trials of stimulation, even in a single sitting. Since deep inspiration is also an effective stimulus to elicite SSR, the present study was conducted to assess the influence of respiration on SSR. Thirty-four healthy students participated in the study. The skin of the forearm of the dominant hand was stimulated by electrical square pulse and SSR was recorded from the ipsilateral hand. SSR was elicited and recorded in each subject during the various phases of respiration, namely, end expiration (EE), end inspiration (EI), mid expiration (ME) and mid inspiration (MI). It was observed that the mean values of SSR latency during these respiratory phases (EE : 1.59, EI: 1.51, ME : 1.55, and MI: 1.56 sec) were similar, indicating that the normal respiration might not be responsible for the observed interstimulation variations in latency in any given individual.

Adolescent↗
PubMed1977

[Changes in body weight and respiration rate in loach embryos].

Changes in the raw and dry weight of the intact eggs and isolated embryos of the loach, as well as in the respiration rate have been followed from 3.5 (64 blastomeres) till 46 hrs of development (prior to hatching). The raw weight of the intact eggs was shown to decrease somewhat. The dry weight of the isolated embryos increases twice. The respiration rate of the embryos increases 6.3 times. The intensity of respiration translated per dry and raw weight of the embryos increases as well. The protein content increases more than thrice.

Animals↗
PubMed1976

[Regulation of respiration under conditions of inhibition of carbonic anhydrase activity by diamox].

The functional state of the respiratory center and the mechanism of increase in pulmonary ventilation before and after inhibition of activity of carbonic anhydrase by diamox were studied in anesthetized cats. During the inhibition, activity of bulbar inspiratory neurons functionally connected with motoneurons of the diaphragm was markedly reduced and that of the neurons connected with motoneurons of intercostal muscles was sharply increased. A steady thoracic respiration occurred. The aferents from the carotid sinus nerve and vagus nerve did not affect the steady thoracic respiration. Increased efferent influence upon the intercostal muscles led to forced thoracic respiration which ensured a high pulmonary ventilation during the whole period of action of the diamox.

Acetazolamide↗
PubMed1976

[Artificial respiration for the postoperative care after major surgery (author's transl)].

An analysis was made of the postoperative course of 158 cases of major surgery performed during 1971-1973. The operations comprised thoraco-abdominal resection of the oesophageal and cardia, abdominal duodenopancreatectomy, partial gastrectomy and enterectomy and partial hepatectomy. 63 per cent of the patients were given artificial respiration either prophylactically immediately after the operation (47 per cent) or at a later stage (53 per cent) on account of respiratory complications (arterial hypoxia below 55 mm Hg pO2). Postoperative mortality for the group of patients who did not have artificial respiration was 46 per cent, as compared with 32 per cent for the artifically ventilated patients - a difference of 14 per cent. The causes for this discrepancy, and especially the role of non-respiratory complications are discussed and the indications for prophylactic postoperative artificial respiration are reviewed.

Cardia↗
PubMed1998

[Continuous pressure is preferred to flow triggering of respiration in the apnea test following the protocol for brain death determination].

The apnea test is part of the brain death protocol of the National Health Council. If the patient is being given positive end-pressure respiration, he must not be uncoupled from the respirator. The apnea test should then be done by means of continuous positive airway pressure. Pressure triggering rather than the extremely sensitive flow triggering should then be chosen to trigger the respiration, since otherwise the patient may unjustifiably be declared 'not brain dead' as a result of slight aspecific movements (bumping against the bed, beating of the heart).

Apnea↗