Postural effects on blood gas tension, blood pressure, heart rate, ECG and respiratory rate during prolonged anaesthesia in the horse.
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Anesthesia, General↗
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[Heart rate, pulse and respiratory rate in a group of students between 14 and 19 years].
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Adolescent↗
[Proceedings: Relationship between basal metabolism (BM) and the product of heart rate multiplied by respiratory rate (HR times RR)].
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Adolescent↗
The effect of temperature reduction on respiratory rate in febrile illnesses.
A raised respiratory rate is a useful sign in the diagnosis of pneumonia in children. It was observed that children with malaria and other febrile illnesses may also present with a raised respiratory rate. To determine the extent to which increased body temperature contributes to the raised respiratory rate observed in these children the effect of change in body temperature on respiratory rate was measured in 186 sick Gambian children with a raised respiratory rate, including those with pneumonia or malaria. A temperature dependent effect on respiratory rate of 3.7 breaths per minute per degree centigrade was demonstrated for the whole study cohort, with no significant difference between children with pneumonia or malaria. Twenty three per cent of children with pneumonia whose temperature fell had a final respiratory rate below that currently recommended by the World Health Organisation for the diagnosis of pneumonia. It is concluded that respiratory rate is to some extent dependent on body temperature in children with febrile illnesses such as pneumonia and malaria, but that this does not alone account for the raised respiratory rate seen in these children. The effect of reduction in body temperature on respiratory rate does not help to distinguish children with pneumonia from those with malaria. A history of recent use of an antipyretic or other measures to control fever is important when evaluating children for possible pneumonia.
Body Temperature↗
Long-term effect of introducing an early warning score on respiratory rate charting on general wards.
The respiratory rate is an early indicator of disease, yet many clinicians underestimate its importance and hospitals report a poor level of respiratory rate recording. We studied the short- and long-term effects of introducing a new patient vital signs chart and the modified early warning score (MEWS), which incorporates respiratory rate on the prevalence of respiratory rate recording in six general wards of our hospital. Prior to the commencement of the study, the average percentage of occupied beds where at least one respiratory rate recording had been made in a single 24-h period was 29.5+/-13.5%. After the introduction of the new vital signs chart to all six wards, and the introduction of MEWS to three wards, this rose to 68.9+/-20.9%. When all six wards had been using both the new chart and the MEWS system for almost 1 year, the figure had reached 91.2+/-5.6%. During the pre-introduction period, there was no difference in the prevalence of respiratory rate recording between the specialties (orthopaedic, 26.9%; surgery, 32.9%; medicine, 29.8%; p=0.118). During the second two audit periods, the prevalence of respiratory rate monitoring was consistently higher on medical wards than on surgical and orthopaedic wards (p<0.001). The study confirms the long-term beneficial effect of introducing the MEWS system on respiratory rate recording into the general wards of our hospital. As respiratory rate abnormalities are early markers of disease, it is hoped that improved monitoring will have an impact on the nature and timeliness of the response to critical illness. This may have an impact on the future incidence of potentially avoidable cardiac arrest, deaths and unanticipated intensive care unit admission.
Forms and Records Control↗
Respiratory rates in pediatric emergency patients.
Respiratory rates are routinely measured in pediatric emergency patients. The normal range has not been established, and commonly reported ranges seem lower than those encountered in clinical practice. This prospective study selected subjects from pediatric patients presenting for care to a suburban emergency department. All respiratory rates were measured for one full minute. Patients with complaints related to the cardiopulmonary system or with an elevated temperature were excluded. A total of 434 patients were entered into the study over a 3-month period of time. Ages ranged from 2 weeks to 18 years. Respiratory rates ranged from a high of 65 breaths/min in a 4-month-old to a low of 12 breaths/min in a 14-year-old. Respiratory rate was inversely related to age, and there was a broad range in every age group. Our study shows that a normal respiratory rate is inversely related to age and is higher than noted in previously published studies. The wide range of "normal" pediatric respiratory rates makes identification of "abnormal" more difficult.
Adolescent↗
Importance of respiratory rate as an indicator of respiratory dysfunction in patients with cystic fibrosis.
Bedside measurement of respiratory frequency is commonly performed in a cursory manner and judged to be of little clinical importance. However, in a recent study of patients being weaned from mechanical ventilation, we found that tachypnea was quite accurate in predicting an unsuccessful weaning outcome. The present study was undertaken to examine the relationship between nonobtrusive measurements of respiratory frequency, using a calibrated inductive plethysmograph, and detailed measurements of pulmonary function in 11 adult patients with cystic fibrosis of varying severity. Respiratory frequency was increased in the patients with cystic fibrosis compared with a group of healthy control subjects, as was minute ventilation and mean inspiratory flow. Respiratory frequency was a sensitive predictor of respiratory dysfunction, being significantly (p less than 0.05) correlated with airway obstruction (r = 0.76), hyperinflation (r = 0.52), arterial oxygenation (r = -0.59), rib cage-abdominal discoordination (r = 0.54), and maximum ventilation during exercise (r = 0.66). Despite the presence of tachypnea, the patients did not display shallow breathing; indeed, tidal volume was not correlated with any of the above abnormalities. In conclusion, respiratory rate was a useful indicator of respiratory dysfunction in this group of patients with cystic fibrosis.
Adult↗
Relationship between heart rate and minute ventilation, tidal volume and respiratory rate during brief and low level exercise.
The correlation between heart rate (HR) and three respiratory parameters, minute ventilation (VE), tidal volume (Vt), and respiratory rate (RR), were studied. Four healthy subjects performed four exercise tests (duration 30 seconds at 50, 100, 150, or 200 W), in random order. Cardio-respiratory parameters were recorded respiratory cycle by respiratory cycle. The results of these low level exercise tests showed that oxygen consumption (VO2) was strongly correlated with VE (r = 0.91 +/- 0.10; P less than 0.01) (except in one test) and Vt (r = 0.91 +/- 0.07; P less than 0.001) (except in one test). There was no significant correlation between VO2 and RR. At exercise onset HR, VE, and Vt were modified in a matter of a few heart beats while RR varied depending on the subject and the level of exercise. During exercise average HR, VE, and Vt were significantly higher than at rest in most cases; but RR was not significantly changed by exercise. The correlations between HR and VE, Vt and RR varied from one individual to another. Nevertheless, the correlation coefficients were positive for VE and Vt, while they were negative for RR. Sensing respiratory rate thus appears to be insufficient for responsive pacing at exercise onset, but sensing respiratory volumes (Vt, VE) should give satisfactory results.
Adult↗
Rate-adaptive pacemaker controlled by motion and respiratory rate using neuro-fuzzy algorithm.
Rate-adaptive pacemakers use information from sensors to change the rate of heart stimulation. Until now, fuzzy-pacemaker algorithms have been used to combine inputs from sensors to improve heart rate control, but they have been difficult to implement. In this paper, a pacemaker algorithm which controlled heart rate adaptively by motion and respiratory rate was studied. After chronotropic assessment exercise protocol (CAEP) tests were performed to collect activity and respiratory rate signals, the intrinsic heart rate was inferred from these two signals by a neuro-fuzzy method. For 10 subjects the heart rate inference, using the neuro-fuzzy algorithm, gave 52.4% improved accuracy in comparison with the normal fuzzy table look-up method. The neuro-fuzzy method was applied to a real pacemaker by reduced mapping of the neuro-fuzzy look-up table.
Adaptation, Physiological↗
The vexatious vital: neither clinical measurements by nurses nor an electronic monitor provides accurate measurements of respiratory rate in triage.
STUDY OBJECTIVE: Of all the vital signs, only respiratory rate is still measured clinically in most US triage systems. Previous studies have demonstrated the inaccuracy, poor interobserver agreement, and low variability of routine measurements of respiratory rate. We assess the variability and accuracy of triage nurses' measurements of respiratory rate against a criterion standard. Also, we assess electronic measurement of respiratory rate against the same criterion standard. METHODS: Consecutive patients presenting to an urban teaching emergency department (ED) were enrolled in this prospective study. Electronic measurement of respiratory rate was recorded throughout the triage encounter when nurses were recording measurements of respiratory rate. Electronic respiratory rate was measured using transthoracic impedance plethysmography. Immediately after each triage evaluation, criterion standard measurements of respiratory rate were made by research assistants using the World Health Organization recommendation of auscultation or observation for 60 seconds. RESULTS: We enrolled 159 patients. Variability was low for triage nurses' measurements of respiratory rate (SD 3.3) and electronic measurement of respiratory rate (SD 4.1) compared with criterion standard measurements of respiratory rate (SD 4.8; P <.05). Triage nurses' measurements of respiratory rate and electronic measurement of respiratory rate showed low sensitivity in detecting bradypnea and tachypnea. In a Bland-Altman analysis, triage nurses' measurements of respiratory rate and electronic measurement of respiratory rate showed poor agreement with criterion standard measurements of respiratory rate. Subgroup analysis of patients presenting with cardiac and respiratory symptoms yielded similar results. CONCLUSION: Neither triage nurses nor an electronic monitor provides accurate measurements of respiratory rate in the ED. Emergency physicians should search for new electronic modalities for measuring respiratory rate to bring respiratory rate into line with other vital signs. Emergency physicians should also consider new clinical strategies for measuring respiratory rate.
Adolescent↗
Interrater reliability of craniosacral rate measurements and their relationship with subjects' and examiners' heart and respiratory rate measurements.
BACKGROUND AND PURPOSE: The evaluation of craniosacral motion is an approach used by physical therapists and other health professionals to assess the causes of pain and dysfunction, but evidence for the existence of this motion is lacking and the reproducibility of the results of this palpatory technique has not been studied. This study examined the interexaminer reliability of craniosacral rate and the relationships among craniosacral rate and subjects' and examiners' heart and respiratory rates. SUBJECTS: Participants were 12 children and adults with histories of physical trauma, surgery, or learning disabilities. Three physical therapists with expertise in craniosacral therapy were the examiners. METHODS: One of three nurses recorded heart and respiratory rates of both subject and examiner. The examiner then palpated the subject to determine craniosacral rate and reported the findings to the nurse. Each subject was examined by each of the three examiners. RESULTS: Reliability was estimated using a repeated-measures analysis of variance and the intraclass correlation coefficient (2,1). Significant differences among examiners and the scatter plot of rates showed lack of agreement among examiners. The ICC was -.02. The correlations between subject craniosacral rate and subject and examiner heart and respiratory rates were analyzed with Pearson correlation coefficients and were low and not statistically significant. DISCUSSION AND CONCLUSIONS: Measurements of craniosacral motion did not appear to be related to measurements of heart and respiratory rates, and therapists were not able to measure it reliably. Measurement error may be sufficiently large to render many clinical decisions potentially erroneous. Further studies are needed to verify whether craniosacral motion exists, examine the interpretations of craniosacral assessment, determine the reliability of all aspects of the assessment, and examine whether craniosacral therapy is an effective treatment. [Wirth-Pattullo V. Hayes KW. Interrater reliability of craniosacral rate measurements and their relationship with subjects' and examiners' heart and respiratory rate measurements.
Adolescent↗
Reference values for respiratory rate in the first 3 years of life.
BACKGROUND: Raised respiratory rate is a useful sign to diagnose lower respiratory infections in childhood. However, the normal range for respiratory rate has not been defined in a proper, large sample. OBJECTIVE: To assess the respiratory rate in a large number of infants and young children in order to construct percentile curves by age; to determine the repeatability to the assessment using a stethoscope and compare it with observation. METHODS: Respiratory rate was recorded for 1 minute with a stethoscope in 618 infants and children, aged 15 days to 3 years old, without respiratory infections or any other severe disease when awake and calm and when asleep. In 50 subjects we compared respiratory rate taken 30 to 60 minutes apart to assess repeatability, and in 50 others we compared simultaneous counts obtained by stethoscope versus observation. RESULTS: Repeatability was good as the standard deviation of differences was 2.5 breaths/minute in awake and 1.7 breaths/minute in asleep children. Respiratory rate obtained with a stethoscope was systematically higher than that obtained by observation (mean difference 2.6 breaths/minute in awake and 1.8 breaths/minute in asleep children; P = .015 and P < .001, respectively). A decrease in respiratory rate with age was seen for both states, and it was faster in the first few months of life when also a greater dispersion of values was observed. A second degree polynomial curve accurately fitted the data. Reference percentile values were developed from these data. CONCLUSIONS: The repeatability of respiratory rate measured with a stethoscope was good. Percentile curves would be particularly helpful in the first months of life when the decline in respiratory rate is very rapid and prevents to use cut off values for defining "normality."
Aging↗
Cardiac pacemaker regulated by respiratory rate and blood temperature.
A new method using respiratory rate and temperature as the guides for optimal pacing is proposed. A pacemaker was fabricated which senses these two parameters simultaneously. The pacemaker functions by calculating the cardiac rate, which would be derived from the respiratory rate and the blood temperature. The higher of the two rates is adopted as the cardiac pacing rate, i.e., at which stimuli will be delivered. The operation was tested in a mongrel dog with complete atrioventricular block. After the induction of anesthesia, a thermistor temperature probe was inserted into right atrium and a respiratory rate sensor was attached around the chest. After administration of a pyrogenic drug, both respiratory rate and blood temperature increased. The pacing rate was increased from 178 beats/minute(bpm) at 36.4 degrees C, blood temperature, and 26.5 acts/minute(apm), respiratory rate, to 233 bpm at 40.1 degrees C and 40.0 apm. Cardiac output was increased from 2.15 liters/minute(l/pm) at the beginning to 2.50 l/pm at maximum. The transition of the guide from respiratory rate to temperature was observed at about 38 degrees C.
Animals↗
Reference ranges for respiratory rate measured by thermistry (12-84 months).
Previous studies of respiratory rate in children have had a number of methodological problems. The aim of this study was to construct age specific reference ranges for respiratory rate. Respiratory rate in children attending childcare centres, kindergartens, and schools was measured using a nasal thermocouple to obtain respiratory waveforms. Reference ranges were constructed using data from 293 awake children between 12 and 84 months, and from 123 sleeping children between 12 and 60 months. The mean respiratory rate declined with increasing age and was significantly lower, with lower variability, during sleep than wakefulness. Neither the awake nor sleeping reference ranges were significantly affected by sex, nor by the presence of past respiratory nor current respiratory symptoms.
Age Factors↗
Rate-responsive pacing with a pacemaker that detects respiratory rate (Biorate): clinical advantages and complications.
The respiratory-dependent pacemaker (RDP3 or MB-1, Biorate, Biotec International, S.p.A., Bologna, Italy) detects the respiratory rate by measuring thoracic impedance using a subcutaneous auxiliary lead. The sensed respiratory rate is used to determine the pacing rate response. This pacemaker had been implanted in 9 patients with a mean age of 58 (range 42-69) years. During symptom-limited treadmill exercise, rate-modulated pacing resulted in a significant increase in pacing rate (mean +/- SD, 124 +/- 10 vs. 71 +/- 3 beats/min p less than 0.001) and exercise capacity (343 +/- 147 vs. 463 +/- 120 s, p less than 0.05) compared to those achieved with constant rate ventricular pacing. Brief treadmill exercise tests showed appropriate rate response to increased walking speed and gradient. However, rate response was modified by arm swinging-induced motion artefact which affected the measured "impedance." Complications observed on follow-up included perforation of the auxiliary lead in 2 patients and symptomatic myopotential interference in 3 patients with the RDP3 pacemaker, all of whom required unit replacement. It is concluded that although the respiratory-dependent pacemaker can confer physiological benefit in patients with bradycardia, myopotential interference (largely overcome by the new version MB-1 with programmable sensitivity) and the auxiliary lead can be problematic in some patients.
Adult↗
Continuous noninvasive monitoring of respiratory rate in critically ill patients.
Respiratory rate is a sensitive clinical parameter in a multitude of pulmonary diseases, especially in the critical care setting. In order to validate the routine recording of the respiratory rate in the intensive care unit, we compared the values obtained from the nursing records with the breathing frequency continuously recorded by a prototype microprocessor system using respiratory inductive plethysmography. We found a significant (greater than or equal to 20 percent) error in the staff's monitoring of respiratory rate one third of the time. In addition, we demonstrated the ease and reliability of using this prototype system as a continuous, noninvasive, long-term respiratory monitor in the intensive care unit.
Adult↗
Rates of rewarming, heart and respiratory rates and their significance for oxygen transport during arousal from torpor in the smallest mammal, the Etruscan shrew Suncus etruscus.
We investigated the process of rewarming from torpor with respect to respiratory and circulatory oxygen transport properties in the smallest mammal, the Etruscan shrew Suncus etruscus. In seven adult Etruscan shrews with a mean body mass of 2.4g, torpor was induced by deprivation of food and a cold environment. During arousal from torpor at an ambient temperature of 22 degrees C, the shrews actively rewarmed from the lowest mean (+/- S.D.) body temperature (Tb) of 12.1 +/- 1.2 degrees C to 20 degrees C at a rate of 0.43 +/- 0.14 degree C min-1, from 20 to 24 degrees C at a rate of 0.8 degree C min-1, and from 24 to 36 degrees C at a rate of 1.1 +/- 0.1 degrees C min-1. The mean rate from 12 degrees C to normothermia amounted to 0.83 degree C min-1, which is among the highest values recorded in mammals. During rewarming, the heart rate increased exponentially (Q10 = 2.2) from 100 to 800-1200 min-1, whereas the respiratory rate increased linearly from 50 to 600-800 min-1. These rates are higher than the heart and respiratory rates reported for other small mammals at the same Tb. The fraction of brown adipose tissue (BAT) was 9.2 +/- 1.6% of body mass, which is higher than in any other mammal. Up to a body temperature of approximately 17 degrees C, the heat for rewarming was mainly produced in the BAT; above this value, considerable activity of the skeletal muscles enhanced thermogenesis. Estimation of the mixed venous oxygen partial pressure showed that, at the tissue level, the rewarming process corresponds to heavy work conditions. The ventilatory system is adapted such that during rewarming, in addition to the appropriate oxygen transport capacity, there is also a capacity for hyperventilation.
Animals↗
Increasing respiratory rate to improve CO2 clearance during mechanical ventilation is not a panacea in acute respiratory failure.
BACKGROUND: Increasing respiratory rate has recently been proposed to improve CO2 clearance in patients with acute respiratory failure who are receiving mechanical ventilation. However, the efficacy of this strategy may be limited by deadspace ventilation, and it might induce adverse hemodynamic effects related to dynamic hyperinflation. SETTING: An intensive care unit of a university hospital. PATIENTS: We studied 14 patients with acute respiratory failure during the adjustment of ventilator settings on the first day of mechanical ventilation in volume-controlled mode. MEASUREMENTS: After determining the positive end-expiratory pressure that suppresses any intrinsic positive end-expiratory pressure at a respiratory rate of 15 breaths/min, we compared blood gas analysis, respiratory measurements, and Doppler evaluation of right ventricular systolic function by using two different respiratory strategies with the same airway pressure limitation (plateau pressure, < or =25 cm H2O), a low-rate conventional respiratory strategy with a respiratory rate of 15 breaths/min, and a high-rate strategy with a respiratory rate of 30 breaths/min. RESULTS: Compared with the low-rate strategy, the high-rate strategy neither significantly reduced PaCO2 (47 +/- 8 vs. 51 +/- 7 mm Hg with the low-rate strategy) nor significantly improved PaO2 (99 +/- 40 vs. 95 +/- 35 mm Hg with the low-rate strategy). It significantly increased alveolar deadspace to tidal volume ratio (21% +/- 8%, vs. 14% +/- 6% with the low-rate strategy) and produced dynamic hyperinflation, resulting in a substantial intrinsic positive end-expiratory pressure (6.4 +/- 2.7 cm H2O). Right ventricular outflow impedance was increased, resulting in a significant drop in the cardiac index (2.9 +/- 0.6 vs. 3.3 +/- 0.7 L/min/m with the low-rate strategy). CONCLUSION: We conclude that a high respiratory rate strategy during mechanical ventilation in patients with acute respiratory failure did not improve CO2 clearance, produced dynamic hyperinflation, and impaired right ventricular ejection.
Acute Disease↗