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At least 163 records · Page 9Linked to original sources
PubMed2005

A new fiberoptical respiratory rate monitor for the neonatal intensive care unit.

A new technique for respiratory rate measurement in the neonatal intensive care unit, fiberoptic respirometry (FORE), was tested using a specially designed nasal adapter. The aim was to investigate the system's accuracy and compare it to the transthoracic impedance (TTI) method and manual counting (MC). Further, the relationship between accuracy and degree of body movement was investigated. Seventeen neonates of median gestational age 35 weeks were included in the study. Video recordings (synchronized with data recordings) were used for classification of body movement. Breaths per minute data were obtained for 23-32-min periods per child, and a subset of these included MC performed by experienced nurses. A Bland-Altman analysis showed low accuracy of both FORE and TTI. A >20% deviation from MC was found in 22.7% and 23.8% of observations for the two methods, respectively. Both methods had accuracy problems during body movement. FORE tended to underestimate respiratory rate due to probe displacement, while TTI overestimated due to motion artefacts. The accuracy was also strongly subject-dependent. The neonates were undisturbed by the FORE device. In some cases, though, it was difficult to keep the adapter positioned in the airway. Further development should, therefore, focus on FORE adapter improvements to maintain probe position over time.

Female↗
PubMed1989

Effect of pulmonary venous congestion on respiratory rate in dogs.

1. The effect of pulmonary venous congestion on the respiratory rate was examined in dogs anaesthetized with alpha-chloralose. The study was done on both spontaneously breathing and artificially ventilated animals. Pulmonary venous congestion was produced by partial obstruction of the mitral valve sufficient to raise the left atrial pressure by 5 mmHg. 2. In artificially ventilated dogs, pulmonary venous congestion increased significantly the activity in phrenic nerves. Both the number of bursts/min and the total number of impulses/min increased. However, there was no significant change in the number of impulses/burst. 3. In spontaneously breathing dogs, pulmonary venous congestion produced a significant increase in the frequency of breathing with a significant shortening of the inspiratory and expiratory durations. 4. Cooling of the cervical vagi to 8-9 degrees C abolished both the above responses. 5. Pulmonary venous congestion (left atrial pressure +5 mmHg) stimulated the rapidly adapting receptors of the airways. This effect was abolished by cooling the ipsilateral vagus proximally to 8-9 degrees C. 6. It is concluded that pulmonary venous congestion increases the respiratory rate reflexly in dogs. The afferent pathway for this reflex response resides in the vagus and the rapidly adapting receptors are likely to be the receptors involved in this response.

Action Potentials↗
PubMed2000

Accuracy of capnography with a 30 foot nasal cannula for monitoring respiratory rate and end-tidal CO2 in children.

We tested the accuracy of a low flow (50 cc/min) sidestream capnography system equipped with an experimental 30-foot nasal cannula to monitor ventilatory status in children. End-tidal CO2 and respiratory rate, both at room air and in the presence of supplemental oxygen, were recorded simultaneously from the experimental 30-foot nasal cannula and the standard, FDA approved, 10-foot nasal cannula. The 30-foot nasal cannula was as accurate as the 10-foot nasal cannula in measuring respiratory rate and end-tidal CO2 in children. When supplemental oxygen was delivered by face-mask, there was no dilutional effect on the respiratory rate or end-tidal CO2 recorded with either the 10-foot or 30-foot nasal cannulas in place.

Adolescent↗
PubMed1983

Effect of propylthiouracil, and of bacterial endotoxin (LPS), on thyroid hormones, respiratory rate, cutaneous and renal blood flow in rabbits.

Rabbits in a warm environment reacted to i.v. injections of 10 mg/kg propylthiouracil (PTU) with an immediate fall of serum triiodothyronine (T3) concentration, associated with decreases of respiratory rate and cutaneous blood flow. Simultaneously renal blood flow increased, while arterial blood pressure fell slightly. A rise in the animals' core temperature by 1.1 degree C, on average, contributed to the impression that PTU mimicked the stimulation of the normal thermoregulatory response pattern of cold defence. The cardiorespiratory responses to PTU were found to be augmented 6-8 days after thyroidectomy, but were completely abolished 16-20 days after thyroidectomy or chronic PTU treatment. In chronically thyroidectomized rabbits, i.v. injections of T3, but not of T4, elicited panting and cutaneous vasodilatation. The acute effects of injecting i.v. bacterial endotoxin (LPS) into rabbits in a warm environment consisted of cutaneous vasoconstriction and a decrease in respiratory rate, i.e. in an autonomic cold defence response, which was associated with a sustained increase in serum T3 concentration and caused core temperature, T3 serum concentration decreased again, whilst simultaneously the autonomic activity pattern changed to that of heat defence, comprising a rise in respiratory rate and skin vasodilatation. The results suggest the hypothesis that, similarly to a decrease of serum T3, LPS activates neurones in the CNS which secrete the thyrotropin-releasing hormone (TRH). This, in turn, elicits cardiorespiratory adjustments similar to those observed in the cold, while the opposite response occurs if these TRH secreting neurones are inhibited.

Animals↗
PubMed1999

[A method of detecting respiratory rate with a high-sensitivity capacitance transducer].

Objective. To introduce a simple and low cost respiratory rate detection method. Method. A high-sensitivity capacitance transducer and corresponding detecting system were used in the system. Result. Satisfactory signals were obtained at the upper portion of the right thorax with the method. Conclusion. It could be used widely. It can be used to comprise the respiratory module in multi-parameter patient monitoring, or be used alone to detect respiratory rate.

Equipment Design↗
PubMed1981

Potentiation of the morphine-induced respiratory rate depression by captopril.

The effects of morphine and captopril, an angiotensin-converting enzyme inhibitor, on respiratory frequency have been investigated in non-anesthetized mice. Morphine (10.0 mg/kg) reduced the respiratory frequency which gradually returned to the control level 2 h after the injection. The same dose of morphine when given together with captopril (0.1 and 1.0 mg/kg), caused a similar reduction in respiratory rate. This respiratory depression however, persisted until the end of the observation period. Similar results were obtained with the same dose of morphine in mice pretreated with captopril. The minimal dose of morphine reducing respiratory frequency (3.0 mg/kg), when given to the mice pretreated with captopril (0.1 mg/kg) caused a significant reduction in respiratory frequency and this effect was equal to that obtained with 10.0 mg/kg morphine alone. The results are discussed from the point of the possible inhibitory effect of captopril on the enkephalin degrading enzyme(s).

Aminopeptidases↗
PubMed1998

Effect of respiratory rate on the relationships between RR interval and systolic blood pressure fluctuations: a frequency-dependent phenomenon.

OBJECTIVE: The aims of this study were to determine the relationships between oscillations in systolic blood pressure and heart period at different breathing frequencies and to investigate the role of sympathetic contribution to this relationship. METHODS: Fourteen healthy volunteers underwent three randomized periods of controlled breathing at 6, 10 and 16 breaths/min. ECG (RR), respiratory signal (RESP) and systolic blood pressure (SBP) were continuously recorded. The component of RR and SBP oscillations related to respiration (RRResp and SBPResp) was defined by means of uni- and bivariate spectral analysis. The squared coherence (K2) and phase between RR and RESP, and RR and SBP (RR-SBP) were also assessed. When the K2 of RR-SBP in the respiratory band was > 0.5, we considered the phase and calculated the closed-loop gain between the two signals. Seven subjects were also studied after chronic metoprolol treatment. RESULTS: Although the mean values of RR and SBP did not differ between the three periods of breathing, the higher the respiratory rate, the smaller the RRResp and SBPResp. The phase was always negative (SBPResp changes preceded RRResp changes), thus suggesting a baroreflex link. The higher the respiratory rate, the lower the gain and phase. Pharmacological beta-adrenoceptor blockade increased the gain and shifted the phase, but the relationships found at baseline between the respiratory rate and both the gain and phase remained unchanged. CONCLUSIONS: The effect of breath rate on the relationship between heart rate and systolic pressure variabilities is a frequency-dependent phenomenon that is also independent of the sympathetic drive.

Adrenergic beta-Antagonists↗
PubMed1998

Usefulness of D-dimer, blood gas, and respiratory rate measurements for excluding pulmonary embolism.

BACKGROUND: A study was undertaken to assess the usefulness of the SimpliRED D-dimer test, arterial oxygen tension, and respiratory rate measurement for excluding pulmonary embolism (PE) and venous thromboembolism (VTE). METHODS: Lung scans were performed in 517 consecutive medical inpatients with suspected acute PE over a one year period. Predetermined end points for objectively diagnosed PE in order of precedence were (1) a post mortem diagnosis, (2) a positive pulmonary angiogram, (3) a high probability ventilation perfusion lung scan when the pretest probability was also high, and (4) the unanimous opinion of an adjudication committee. Deep vein thrombosis (DVT) was diagnosed by standard ultrasound and venography. RESULTS: A total of 40 cases of PE and 37 cases of DVT were objectively diagnosed. The predictive value of a negative SimpliRED test for excluding objectively diagnosed PE was 0.99 (error rate 2/249), that of PaO2 of > or = 80 mm Hg (10.7 kPa) was 0.97 (error rate 5/160), and that of a respiratory rate of < or = 20/min was 0.95 (error rate 14/308). The best combination of findings for excluding PE was a negative SimpliRED test and PaO2 > or = 80 mm Hg, which gave a predictive value of 1.0 (error rate 0/93). The predictive value of a negative SimpliRED test for excluding VTE was 0.98 (error rate 5/249). CONCLUSIONS: All three of these observations are helpful in excluding PE. When any two parameters were normal, PE was very unlikely. In patients with a negative SimpliRED test and PaO2 of > or = 80 mm Hg a lung scan is usually unnecessary. Application of this approach for triage in the preliminary assessment of suspected PE could lead to a reduced rate of false positive diagnoses and considerable resource savings.

Antifibrinolytic Agents↗
PubMed1988

Electrical potential difference and ion transport across nasal epithelium of term neonates: correlation with mode of delivery, transient tachypnea of the newborn, and respiratory rate.

We studied the change in ion transport function by measuring the basal transepithelial potential difference (PD) across the ciliated epithelium of the nose in 85 term neonates during the first 72 hours of life. Differences in PD associated with the mode of delivery or the presence of respiratory disease and differences in the PD response to the superfusion of amiloride (10(-5) mol/L) were assessed. We also studied term neonates with transient tachypnea of the newborn (TTN) and acute respiratory insufficiency. Basal PDs during the first 24 hours of life were higher in neonates delivered by cesarean section without prior labor (-29.7 +/- 2.5 mV) and in those with TTN (-38.5 +/- 6.0 mV) than in neonates born during normal spontaneous vaginal delivery (-23.0 +/- 2.9 mV) or cesarean section with prior labor (-23.7 +/- 0.7 mV) or in those with respiratory insufficiency (-22.4 +/- 2.3 mV). The percentage inhibition of PD by amiloride superfusion (less than 24 hours) was significantly lower in infants with TTN (30.9 +/- 4.9%) and after cesarean section without prior labor (31.8 +/- 2.2%) than in other groups (37.6 +/- 1.6%). By 48 hours, nasal PDs after cesarean section without prior labor and in neonates with TTN had declined; and by 72 hours, values were similar to those in other groups; respiratory rate paralleled the decline in PD. The respiratory rate of neonates with respiratory insufficiency remained high and paralleled the persistence of respiratory distress. Amiloride sensitivity was similar for all groups by 72 hours. These findings indicate (1) that PDs vary with the mode of delivery and support a role for labor in the normal transition of respiratory epithelial ion transport and (2) that TTN is associated with abnormal epithelial ion transport.

Biological Transport↗
PubMed1978

Effect of Fusarium isolates and their filtrates on respiratory rate and chemical analysis of squash plants.

The highly pathogenic isolate stimulated the emergence of the squash seedlings first, caused, however, the highest death rate of the seedlings finally. Fusarium isolates and their culture filtrates inhibited the respiratory rate of squash plants significantly. However, F. oxysporum isolates inhibited respiration more than F. solani isolates. Seasonal changes of respiration decline show that the respiratory rate decreased with plant growth in the case of infested soil and of plants injected with culture filtrates. However, spraying Fusarium culture filtrates on the foliage gave opposite results when the plants grew older. Fusarium solani isolates decreased nitrogen content of squash stems and leaves, while F. oxysporum isolates gave reverse results. Injecting Fusarium culture filtrate into the plant decreased nitrogen content of both stems and leaves, while spraying the foliage with the filtrates increased nitrogen content more than that of the control. Phosphorus content of the stems of squash plants, sown in infested soil, was less than in the control when the plants were treated with F. solani and higher when they were treated with F. oxysporum isolates. On the other hand, the phosphorus content of squash leaves was higher than in the control. In the case of injected plants, however, the phosphorus content in stems and leaves was equal to that of the control or less, and with sprayed plants it was higher than in the control. Infesting the soil with Fusarium isolates and spraying the foliage with their culture filtrates increased potassium content of squash stems and leaves, while injecting the filtrates into the plants decreased potassium content of both stems and leaves.

Fusarium↗
PubMed2001

Development of real-time image sequence analysis for evaluating posture change and respiratory rate of a subject in bed.

An image sequence analysis technique was developed to evaluate posture change and respiratory rate of a subject in bed without any physical contact. Although the image sequence analysis requires many calculations, the system can perform them in real time. The system consisted of a CCD video camera and a PC equipped with a high-speed image processor. To evaluate the system, we tested it on five subjects at a nursing home. The system evaluated 99.4% of the movements of subjects during the total monitoring time (about 61 hours). The waveform was flat when the subject was out of view of the video camera. The system has the possibility of evaluating not only posture changes and respiratory rate. but also sleeping patterns.

Adult↗
PubMed1995

A direct involvement of the central nervous system in hypophagia and inhibition of respiratory rate in rats after treatment with O,O,S-trimethyl phosphorothioate.

O,O,S-Trimethyl phosphorothioate (OOS-TMP) is known to induce unique symptoms, which are characterized by hypophagia, progressive weight loss, and hypothermia. To determine whether there is the possibility of a causal relationship between these toxic symptoms and a direct action of OOS-TMP on the central nervous system, we investigated the development of these symptoms in Fischer 344 female rats after oral or intracerebral treatment with OOS-TMP. Oral administration of OOS-TMP at 20 mg/kg induced marked hypophagia, progressive weight loss and hypothermia. Moreover, inhibition of respiratory rate was observed immediately after treatment. It lasts during the entire experimental period. Profound hypothermia below 34 degrees C was observed more frequently in the rats, which became hypercapnic (PaCO2 > or = 50 mmHg). In contrast, administration of OOS-TMP at 20 mg/kg (as much as the oral dose) into the cerebral lateral ventricle succeeded in inducing hypophagia, progressive weight loss and lowered respiratory rates. On the other hand, by this route of administration, OOS-TMP at 20 mg/kg failed to induce hypothermia, hypercapnia and lung injury. The present results suggest that hypophagia and inhibitions of respiratory rate are attributable to the direct action of OOS-TMP on the central nervous system, while other symptoms are associated with lung injury.

Administration, Oral↗
PubMed1992

[Biologic rhythm of respiratory rate in the first trimester of life].

This study was designed to address the following objectives: 1) To record the respiratory rate in a population of newborns and infants. 2) To verify the existence of a rhythm in each population group, as well as the organization and maturing process of these rhythms. 3) To determine the possible influence of environmental factors on these rhythms. The study population consisted of the following groups and ages: A) 1 day (21 cases); B) 7 (15 cases); C) 15 (10 cases); D) 30 (17 cases); E) 60 (17 cases); F) 90 (18 cases). Respiratory rate was continuously monitored and recorded, as well as environmental light, noise and temperature. Rhythmometric analysis of the data was done by simple Cosinor test and analysis of variance. The zero amplitude test showed statistically significant differences in the circadian rhythm of groups E and F (p < 0.005). An ultradian rhythm of 3 hours was detected in groups D and F. Environmental factors also showed a circadian rhythm. The appearance of an ultradian rhythm suggest the maturation in a rhythm. To evaluate physiological parameters, reference to time series must be considered.

Female↗
PubMedDate not supplied

Effects of the enkephalin analogue FK33-824 on rectal temperature and respiratory rate in male mice.

Subcutaneous administration of the enkephalin analogue FK33-824 (FK) elicited a dose-related decrease in rectal temperature and respiratory rate in male ddY strain mice. Naloxone and 3 days' implantation of morphine pellet decreased the effects of FK, suggesting the involvement of opioid receptors and cross-tolerance with morphine to both effects of FK. A positive correlation was found between the FK-induced decrease in rectal temperature and that in respiratory rate among the 6 strains of inbred mice including BALB/c, C3H, A/J, CBA, C57BL/6 and DBA/2. The degree of hypothermia elicited by FK was different among strains, whereas marginal strain difference was seen in the respiratory depression induced by FK. The strain difference in the FK responses may be due to the difference in the opioid receptor subtypes in the brain.

Animals↗
PubMed1988

A new multisensor pacing system using stroke volume, respiratory rate, mixed venous oxygen saturation, and temperature, right atrial pressure, right ventricular pressure, and dP/dt.

A new multisensor pacing device using respiratory rate (RR), stroke volume (SV), oxygen saturation (SO2), temperature (T), right atrial pressure (RAP), right ventricular pressure (RVP) and right ventricular dP/dt, has been developed. It consists of a 7F multisensor catheter and an external pacing unit. It allows simultaneous recording of the input signals and the corresponding data can be compared among the different parameters under identical conditions. Furthermore, several parameters can be combined in such a way as to form a new combination better suitable for rate responsive pacing. The response of each parameter to exercise was studied in 12 healthy volunteers (mean age: 28 years). Exercise testing was carried out using a bicycle ergometer, with workloads up to 200 W. The dynamic characteristics, response and sensitivity to changes of workloads of each parameter were analyzed and compared to one another. SO2 proved to be a quick responding parameter (less than 10 sec) with higher sensitivity in the low exercise range (less than 75 W), T, on the other hand, responded slowly (greater than 30 sec) to exercise changes and had the highest sensitivity in the exercise range beyond 75 W. RR displayed a slow response (greater than 30 sec) and an adequate sensitivity was only found in the upper exercise range (greater than 100 W). SV reacted rapidly to workload changes (less than 10 sec) but showed poor sensitivity at all exercise levels. RAP, RVP and dP/dt displayed quick responses and constantly good sensitivity throughout the workload range. Furthermore, respiratory rate was easily derived from the RAP curve. Special algorithms were developed for each parameter so that pacing rate would reproduce sinus rate behavior. We found that SO2 and all pressure parameter imitated sinus rate response quite well. When using parameter combinations, SO2 and T proved to be superior. Five patients (mean age 68 years) with third degree AV-block were stimulated temporarily using this system. Compared to fixed rate stimulation (VVI 70), exercise performance improved, using SO2 as the input parameter for rate response, by 25% to 50%.

Adult↗
PubMed1980

The emergence of a circadian pattern in respiratory rates: comparison between control infants and subsequent siblings of SIDS.

The objective of the present study is to compare the emergence of a circadian respiratory pattern in subsequent siblings of SIDS and controls infants to see whether the unique time and age of SIDS is correlated with altered circadian manifestations. During the first three months of life, a pattern in respiratory rates emerged which appeared to be the nightly portion of a circadian rhythm. Subsequent siblings of SIDS exhibited transient accelerated maturation of this circadian pattern. During the first month of life, minima in respiratory rates in quiet sleep occurred during the second and third intervals of the night in subsequent siblings, a pattern not seen until three months of age in control infants.

Child↗