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PubMed1973

The significance of the timing of chemoreceptor impulses for their effect upon respiration.

Alveolar partial pressure of carbon dioxide (PACO2) and alveolar partial pressure of oxygen (PAO2) oscillate at the frequency of respiration and the oscillations persist into the arterial blood as oscillations of arterial partial pressure of carbon dioxide (PaCO2) and arterial partial pressure of oxygen (PaO2). Arterial chemoreceptors respond quickly enough to changes in PaCO2 and PaO2 for the arterial oscillations to give rise to oscillations in their afferent discharge at the frequency of respiration. The respiratory centre responds with short latency to afferent impulses reaching it. If a burst of impulses reaches it during an inspiration, the depth of that inspiration, is increased but if the burst arrives during expiration, the succeeding inspiration is little affected. Thus if the peaks of chemoreceptor afferent discharge coincide with inspiration, they have a greater effect on respiration than if they coincide with expiration. The phase relation between the activity of the respiratory centre and the oscillations it produces is determined, inter alia, by the frequency of respiration and the heart output. Thus it may well change in exercise.

Animals↗
PubMed1978

[Methods for simultaneous recording of pharmacodynamic and toxic effects on interior sensitive receptors, respiration and cardiac-circulatory system of guinea pigs (author's transl)].

A method for simultaneous, continuous registration of pharmacodynamic and toxic effects, resp., on pulmonary-stretch receptors, on respiration and on hemodynamics in guinea pigs is described. The following parameters are recorded synchronously by a multi-track recorder: 1. The afferences in the cervical n. vagus; its electrical integration is employed for measuring the total intensity and the ex- and the inhalation intensity, resp., of the afferences; 2. the pneumatogram for measuring the maximum velocity of air flow, duration of the breath phase and parts thereof (in-, and exhalation and postexpiratory pause), and the respiration rate; 3. the diastolic and systolic blood pressure during in- and exhalation and postexpiratory pause; 4. the electrocardiogram (ECG). The normal distribution of the initial values is examined and discussed. Further the initial values measured in three series of experiments are discussed and compared: mono-vagotomy/spontaneous respiration, bivagotomy/spontaneous respiration and artificial respiration/monovagotomy. The results are compared with some experimental and clinical findings from literature.

Animals↗
PubMedDate not supplied

The effect of short term thermal stress on the heart and respiration rates of conscious and anaesthetized chickens.

Heart and respiration rates were measured in eight 6-week-old, White Rock chicks at different ambient temperatures: 24--26 degrees C (neutral), 6.5--8.5 degrees C (low) and 3,95--43.5 degrees C (high). The animals were exposed to these temperatures for 10 min. In both groups the low ambient temperature did not influence the respiration rate, whereas the high temperature caused a significant increase of the respiration rates both in the conscious and anaesthetized birds. In both groups no significant changes in the heart rate at different temperatures were found. Statistically significant differences in the heart and respiration rates between the conscious and anaesthetized chickens were noted only at the low environmental temperature.

Animals↗
PubMed1980

[Measurement of cardiac output by electrical impedance plethysmography during respiration and in apnea].

The measurement of cardiac output by electrical impedance plethysmography (non-invasive technique) may be disturbed by a certain number of factors, including respiration. The authors sought to demonstrate that this factor could be eliminated during measurement calculations. By this method, in 18 adult subjects with coronary artery disease, 50 measurements during respiration and 50 measurements in apnoea (paired measurements) of stroke volume and of cardiac output were performed. Stroke volume was calculated using Kubicek's formula: SV = P(L2/Zo2) (dz/dt min)t Results were as follows: highly significant correlation between values for stroke volume obtained during respiration and in apnoea (r ;.9767; n=50; P < 0.001); highly significant correlation between values for cardiac output obtained under the same conditions (r = 0.9744; n=50; P < 0.001). The authors conclude that with the limits of certain technical conditions of measurement, respiration does not disturb measurements of stroke volume and of cardiac output by electrical impedance plethysmography.

Adult↗
PubMed1981

[Home-respirator treatment in idiopathic hypoventilation (author's transl)].

A report is given on a 66 years old patient with severe idiopathic hypoventilation. Two years ago the disease had developed rather suddenly with severe hypoventilation during sleep, accompanied by marked hypoxemia and hypercapnia with pCO2-values above 100mm Hg and respiratory acidosis. No pulmonary, cardiac or neurological disease was found. After failure of two attempts of stimulation of the phrenic nerve the patient was admitted to a respiratory intensive care unit and ventilated by a respirator during sleep. After improvement of this general condition he was discharged at first only in the daytime, later he could be discharged fully from the unit, after a respirator had been installed in his home. Now the patient is connecting himself to the respirator during sleep and since 20 months is so in a tolerable condition. The indications for home-respirator treatment are discussed.

Aged↗
PubMedDate not supplied

[Effect of hyperbaric oxygenation on respiration in acute cerebral circulatory disorders].

The OKA-MT pressure chambers were used. External respiration was studied by spirography by means of the SG-2M spirograph. From the results of examination of 53 patients with acute cerebral circulatory disorders it was established that hyperbaric oxygen normalizes the initially abnormal external respiration: corrects the periodical rhythms and reduces hyperventilation; the hyperbaric oxygenation sessions have no effect on initially normal respiration; the reaction of external respiration to hyperbaric oxygen changes during the course of treatment depending on the number of sessions; the appearance or intensification of the hyperventilation syndrome after one or three hyperbaric oxygenation sessions in the absence of negative neurological dynamics cannot be assessed as a contraindication for hyperbarotherapy.

Adult↗
PubMed1982

[Effects of methanobenzazonine (2,3,4,5,6,7-hexahydro-1,6-methano-1H-4-benzazonine) derivatives on the cough reflex and respiration].

Antitussive and respiratory effects of three newly synthesized methanobenzazonine derivatives and their d- and l-isomers were investigated to understand the relationship between the cough and respiratory centers. Antitussive effects were evaluated with the PEC (puncture electrode-induced cough) method in conscious d-, dl-, and l-ST-2123; d-, dl-, and l-ST-2121 into the right carotid artery at a dose range of 0.2-0.8 mg caused no effect on respiration. dl-ST-2121 at 0.4 to 0.8 mg and l-ST-2121 at 0.2 to 0.8 mg depressed respiration dose-dependently. Codeine (0.2-0.8 mg) depressed respiration slightly. Morphine (0.2-0.8 mg) depressed respiration more strongly. All the methanobenzazonine derivatives used, when given intraperitoneally, showed antitussive potencies that were 1/3-1/2 the potency of codeine. The antitussive potencies of the d-, dl-, and l-isomers of the three derivatives used were discussed on the bases of chemical structures and drug receptors. These results provide evidence of a discrepancy between the cough and respiratory centers in the brain stem.

Animals↗
PubMed1994

Functional and structural relation between central chemoreception of respiration and the nucleus retrofacialis in rats.

Iontophoresis of hydrogen ions (H+) to respiration related units (RRUs) in the nucleus retrofacialis (NRF) region was used to investigate the role of RRUs in central chemoreception of respiration. The results were as follows: 1) of the 13 inspiration related units (InRUs) recorded, 7 were excitatory and 1 was inhibitory; 2) of the 29 expiration related units (ExRUs), 12 were inhibitory and 1 was excitatory; and 3) of the 7 phase-spanning respiration related units (PSUs), 4 were excitatory and 2 were inhibitory. None of the remainder were affected. Histochemical study using the horseradish peroxidase (HRP) technique revealed a neural structural relation between the ventral surface of the medulla and neurons in the NRF region. It was suggested that the RRUs in the NRF region might contribute to the central chemoreception which regulates respiration.

Animals↗
PubMed1993

[A clinical study on respiratory management using a respirator with nasal intubation in patients undergoing surgery for esophageal cancer].

We analyzed a postoperative respiratory management using a respirator with nasal intubation in 55 patients who underwent subtotal esophagectomy through thoracic and abdominal approach between April 1984 and December 1989. In 21 cases (38%) the period using a respirator was within 3 days, in 24 cases (44%) during 4-7 days, and in 10 cases (18%) over 8 days. Postoperative pulmonary complications occurred in 20 cases (36%); pneumonia in 7 cases (13%), lung edema in 12 cases (22%), atelectasis in one case (2%). Two patient died after surgery, one from acute myocardial infarction, another from multiple organ failure after anastomotic leakage. The period using a respirator was positively correlated with the operative blood loss, transfusion and post-operative infusion, postoperative pulmonary complications positively correlated with the operative time, the anesthetic time, operative blood loss, transfusion and postoperative infusion as well as with preoperative complications and renal dysfunction too. In 120 cases before 1984, postoperative pneumonia occurred in 42 cases (36) and 19 cases (16%) of them died. These results suggest that our respiratory management using a respirator is effective in perioperative period of esophageal cancer.

Aged↗
PubMedDate not supplied

[Significance of the energetic value of respiration in the assessment of the degree of strain of compensatory mechanisms in respiratory insufficiency].

A total of 170 examinations of the external respiration function were carried out in 114 patients with postoperative respiratory insufficiency (RI). The patients were examined during air respiration (FiO2 0.21). Pulmonary function was computer monitored. Thirty-four parameters were analyzed, which characterize pulmonary ventilation, gas exchange, respiratory mechanics, and metabolism. Three groups of patients were distinguished: with moderate, expressed, and maximal stages of energy compensation of RI. Augmentation of RI in the course of the postoperative period was found to be characterized by reduction of lung compliance and increase of aerodynamic resistance of the airways and specific and minute Decompensation of RI develops due to fatigue of the respiratory muscles under conditions of increased energy value of respiration, which is proved by the appearance of a reliable inverse correlation between the minute respiratory volume and increased inhalation and exhalation resistance and between respiratory volume and increased inhalation resistance and of a direct correlation between respiratory volume and lung compliance in patients during the maximal energy compensation of respiratory insufficiency. Hence, the energy value of respiration objectively reflects the strain of the compensatory mechanisms during respiratory insufficiency.

Humans↗
PubMed1995

[Therapy of Cheyne-Stokes respiration with nocturnal oxygen therapy].

Cheyne-Stokes respiration is common in patients with severe congestive heart failure and is associated with significant nocturnal oxygen desaturation and sleep disruption. The pathogenesis of Cheyne-Stokes respiration in patients with congestive heart failure has been well described and is related to prolonged circulation time between the lung and the carotid body mainly due to increased cardiac dimensions, reduced body stores of oxygen and carbon dioxide, disturbance of ventilation and respiratory control due to arousals and a relatively high hypercapnic ventilatory response. Oxygen is likely to reduce Cheyne-Stokes respiration by increasing oxygen and carbon dioxide stores and reduces the hypercapnic ventilatory response. In the following paper we describe a study designed to determine the impact of nasal nocturnal oxygen on Cheyne-Stokes respiration, sleep, peak oxygen consumption during bicycle exercise, cognitive function evaluated by the trailmaking test and daytime symptoms in patients with severe congestive heart failure. The study is designed as a randomized, cross-over, double-blind, placebo-controlled protocol on about 20 patients with a left ventricular ejection fraction < 35%.

Arousal↗
PubMed1977

Microscopy of human fetal lung and the diagnosis of postnatal respiration.

1. The difficulty of correlating the microscopic appearances of the lungs in cases of stillbirth and early postnatal death with the results of hydrostatic tests in these cases is stressed. 2. Histologic criteria which depend on the presence of alveoli as evidence of extrauterine respiration are criticized. 3. The view is submitted that the alveolar pattern is the result of a normal developmental process occurring in utero, possibly accentuated by intrauterine fetal respiratory movements, but independent of extrauterine respiration. 4. The glandlike appearance of the lung which has been illustrated in standard textbooks as an example of unrespired fetal lung is probably seen only in relatively early embryos in whom the problem of respiration is unlikely to arise. 5. At or near term the alveolar pattern in the human fetus has developed, certainly in parts of the lung, to such a degree in utero that it cannot readily be distinguished from the pattern seen in the newly-born infant who has breathed for a short time in an extrauterine environment. 6. This view that the alveolar pattern is already fairly well developed at full-term makes for a more intelligible appreciation of the structural appearances seen in the immediately postnatal lung as well as of the physiology of respiration with the first extrauterine breath. 7. The views outlined for the development of the human lung in utero are completely corroborated by experimental studies on pig embryos, intraocular lung implants and the structure of sequestrated lung tissue unconnected with the respiratory tract. 8. Microscopic examination of the lungs may assist in determining fetal age. 9. The medicolegal significance of these observations is discussed.

Female↗
PubMed1996

Effects of M1 and M2 receptor agonists and blockers on dog respiration.

AIM: To study the effects of M1 and M2 receptor agonists and blockers on dog respiration. METHODS: Using thoracic respiratory transducer and RM-86 multipurpose polygraph to determine respiratory rate (RR), tidal volume (TV), and minute ventilation volume (MVV), and DH-100G blood gas analysis instrument to analyze pO2, pCO2 and pH. RESULTS: Pilocarpine (Pil, an M1-R subtype agonist) 0.5, 1, and 2 mg.kg-1 iv caused increases in RR, MVV, and pO2, and a decrease in pCO2. The excitatory effects of Pil were antagonized by pretreatment with pirenzepine (Pir, 3 mg.kg-1, iv) and scopolamine (Sco, 2 mg.kg-1, iv). The iv injections of a novel M2-R subtype agonist, 6 beta-acetoxy nortropane (6 beta-AN) 2, 5, and 20 micrograms.kg-1 caused decreases in RR, MVV, and pO2 and an increase of pCO2. The actions of 6 beta-AN were antagonized by iv pretreatment with AF-DX116 ¿11-2 [[2-[(diethylamino)methyl]-1-piperidinyl] acetyl]-5, 11-dihydro-6H[2,3-b][1,4]benzodiazepine-6-one, 0.5 mg.kg-1¿ and atropine (Atr, 2 mg.kg-1). Similar results were obtained when smaller doses of Pil (0.2, 0.4, and 0.8 mg.kg-1) and 6 beta-AN (0.25, 0.5, and 1 microgram.kg-1) were injected into the vertebral artery. Pir and Sco also antagonized the excitatory effects of Pil, and AF-DX116 and Atr antagonized the inhibitory effects of 6 beta-AN on respiration. CONCLUSION: Stimulating M1-R of the respiratory center caused excitation of the respiration while stimulating the M2-R subtype caused inhibition of the respiration.

Animals↗
PubMed1998

[Role of nitric oxide in cell respiration].

Nitric oxide (NO) synthesized in a constitutive manner by a cell, acts on effector cells as a physiological regulator of the vascular tone, of platelet inhibition and of neuron-neuron interaction. By contrast, the release for longer periods of time of higher amounts of inducible NO, transforms NO from a physiological mediator into a cytostatic and cytotoxic molecule. The presence of NO synthetase in mitochondria suggests that physiological small amounts of NO could be involved in cellular respiration regulation by inhibition of cytochrome oxidase. Long exposure of cells to NO results in an irreversible inhibition of cellular respiration not dependent on a generalized superoxide or peroxynitrite formation. Cellular respiration inhibition could be reverted by either analyzing complex IV alone, by blocking Complex I or by the addition of gluthation. Therefore, our hypothesis is that suppression of complex IV is a normal physiological effect dependent on NO concentration. When cells are exposed to NO for longer periods of time, thiol groups are nitrosilated in complex I while gluthation transnitrosilates until its level drops to critical values. At this point, cellular respiration is blocked and this could be the pathway by which NO is transformed from a physiological mediator into a pathological molecule. We also believe that thiol nitrosilation and transnitrosilation by gluthation is a critical mechanism involved in oxidative stress prevention.

Cell Respiration↗
PubMedDate not supplied

[Assisted ventilation of the lungs as a method of transition from artificial pulmonary ventilation to spontaneous respiration].

The authors describe the principal methods of assisted ventilation of the lungs used for smooth and safe transition from artificial ventilation to spontaneous respiration: trigger method, intermittent forced ventilation of the lungs, pressure support, permanent positive pressure respiration, jet high-frequency ventilation of the lungs, and two systems of the respirator response to spontaneous attempts of the patient: to pressure change and flow-by change. Basing on their own experience, the authors claim that patients with parenchymatous respiratory insufficiency better tolerate the method of pressure support, whereas those with ventilation respiratory insufficiency can be best treated by intermittent forced ventilation of the lungs. Jet high-frequency ventilation of the lungs may serve a full-value alternative to the flow-by method.

High-Frequency Ventilation↗
PubMed1984

Temporal correlates in brain death. EEG and clinical relationships to the respirator brain.

In a prospective study of 32 cases of brain death, gross and microscopic pathological appearances of the CNS were statistically analyzed and correlated with EEG and clinical findings. The diagnosis of a "respirator brain" is best made grossly after fixation, using commonly known gross pathological criteria. The microscopic changes are more unpredictable and variable than the gross findings. Respirator brain changes that can be relied on to confirm the clinical-EEG diagnosis of brain death generally take about 12 hours to become manifest after electrocerebral silence (ECS) and/or cerebral circulatory arrest, and are unaffected by the time interval between termination of respiratory support and refrigeration of the body or by delays in performance of the autopsy. Loss of brain-stem reflexes, evidence of herniation, and deterioration of the EEG to ECS correlate significantly with the development of a respirator brain in the respirator-dependent, comatose patient.

Adolescent↗
PubMed1997

Tubeless spontaneous respiration technique for pediatric microlaryngeal surgery.

BACKGROUND: Tubeless spontaneous respiration technique for pediatric microlaryngeal surgery may be accomplished using different anesthetic protocols. Two methods, inhalation of volatile anesthetic agents alone and in combination with intravenous propofol, are reviewed with regard to intraoperative airway stability, post-operative morbidity, recovery room course, and halothane concentration required during maintenance anesthesia. DESIGN: Retrospective case series. SETTING: Otolaryngology referral hospital. PATIENTS AND METHODS: Twenty-nine microlaryngeal procedures were performed using tubeless spontaneous respiration technique in children ranging from 2 weeks to 11 years of age. The following 2 anesthetic protocols were used: inhaled volatile anesthetic agents alone in 18 procedures and in combination with intravenous propofol in 11. Anesthesia, surgery, and recovery room times were documented. Specific characteristics of anesthetic maintenance, including total anesthetic gas flow (liters per minute), variations of halothane concentration (percentage), and duration of halothane administration (minutes) were also recorded to calculate the mean concentration of halothane (percentage) delivered to each patient. RESULTS: No statistical differences were observed between the 2 protocols in terms of anesthesia and surgical outcomes. Adjusting for differences in patient age, weight, maintenance duration, and total anesthetic gas flow, the introduction of propofol allowed a statistically significant reduction in the mean concentration of halothane required during maintenance anesthesia. CONCLUSIONS: Both tubeless spontaneous respiration technique protocols proved successful in this study. However, the addition of propofol allowed a significant reduction in the halothane requirement during anesthesia maintenance. This has the potential benefit of decreasing the exposure of operating room personnel to volatile anesthetics during tubeless spontaneous respiration technique.

Anesthesia, General↗
PubMed2000

Diel variations in respiration, excretion rates, and nutritional status of zooplankton from the Pampulha Reservoir, Belo Horizonte, MG.

This investigation is focused on the experimental determination of diel cycles of metabolic activity of zooplankton in a tropical reservoir. Water and zooplankton used in laboratory experiments were collected from the Pampulha reservoir. The experimental units were incubated in the light (1500 Lux) and in the dark at 25.0 +/- 1.0 degrees C during different periods of the diel cycle. At the end of each experiment, the following variables were measured: temperature, dissolved oxygen, ammonia, and orthophosphate as well as the composition, abundance and dry weight of the zooplankton. The specific respiration and excretion rates were determined considering the differences in concentration between experimental and control units. The effect of diurnal cycle on respiration rates was clearly more intense than the effect of light. The average values of respiration rates obtained in the morning hours oscillated between 0. 015 and 0.016 mgO(2)mgDW. hr(-1) (light and dark incubations). At night, these rates were higher and ranged from 0.020 to 0.035 mgO(2)mgDW. hr(-1). Increased biomass of zooplankton and longer incubation times produced lower respiration rates. The excretion rates of ammonia were higher at night, reaching a mean value of 4.2 microgN-NH(4)/mg DW. hr(-1) in illuminated units. The phosphate excretion rates were more elevated in the morning, reaching 0.58 microgP-PO(4)/mg/DW. hr(-1) illuminated vessels. The nanoplankton was able to actively absorb ammonia as well as phosphate. The highest ammonia absorption rates were measured at night, whereas the nanoplankton absorbed phosphorus only in the morning hours. The nutritional status of zooplankton also showed short-term variations. The mean phosphorus content of zooplankton biomass also varied between day and night as well as with incubation time. It ranged from 0.58-2.17%, whereas organic matter variation was more conservative, oscillating around 70-92% in all occasions.

Animals↗