Peak Respiratory Rate Research Articles

Effects of Simulated Altitude on Ventilator Performance

Aeromedical transport of critically ill casualties requires continued safe operation of medical equipment at altitude. We evaluated performance of two ventilators in an altitude chamber. Two ventilators used by the United States Air Force (USAF) Critical Care Air Transport Teams were operated in an altitude chamber at barometric pressure of 754 mm Hg, 657 mm Hg, 563 mm Hg, and 428 mm Hg simulating altitudes of sea level, 4,000, 8,000, and 15,000 feet. At each altitude ventilators were set to deliver three tidal volumes (VT) from 0.25 L to 1.0 L. Airway pressure, timing, flow, and volumes were measured every breath. Measured parameters included VT, positive end-expiratory pressure (PEEP), inspiratory time, expiratory time, inspiratory flow, peak inspiratory pressure, expiratory flow, and respiratory rate. The Impact 754 compensated for changes in altitude maintaining the set VT within 10% of the sea level VT. Tidal volume delivery of the 754 was less precise during operation of the compressor at an inspired oxygen concentration of 0.21. With each increase in altitude, the LTV VT increased. At 8,000 feet VT increased by 10% and at 15,000 feet VT increased by 30% (p<0.001). Respiratory rate was not affected by altitude with either device. The Impact 754 compensates ventilator output to deliver the desired tidal volume regardless of changes in altitude and barometric pressure. The LTV-1000 does not compensate for changes in altitude resulting in delivery of increasing tidal volumes with falling barometric pressure. Clinicians should be aware of ventilator performance and ventilator limitations to provide safe and effective ventilation during transport.

Cardiopulmonary Changes In Pregnant Women In Sabon-Gari Local Government Area, Of Kaduna State, Nigeria

The cardiopulmonary changes among pregnant women were studied in 400 subjects (100 non-pregnant and 300 pregnant). The cardiovascular parameters measured are blood pressure (systolic and diastolic), pulse rate and mean arterial blood pressure by auscultatory method using stethoscope and sphygmomanometer. The pulmonary parameters measured are peak expiratory flow rate (PEFR), using Wright peak flow meter and respiratory rate the number times thoracic cage expands and relaxes. The cardiopulmonary parameters of pregnant women decreased significantly (p 0.05), while in second and third trimester the anthropometric parameters decreases significantly (p<.05) with positive correlation when compared to control. The cardiopulmonary parameters in pregnant women showed a significant changes (p<.05) when compare to non-pregnant.

Influence of exertional oscillatory ventilation on exercise performance in heart failure

Exertional oscillatory ventilation (EOV) in heart failure may potentiate the negative effects of low cardiac output and high ventilation on exercise performance. We hypothesized that the presence of EOV might, per se, influence exercise capacity as evaluated by maximal cardiopulmonary exercise test. We identified 78 severe chronic heart failure patient pairs with and without EOV. Patients were matched for sex, age and peak oxygen consumption (VO2). Patients with EOV showed, for the same peak VO2, a lower workload (WL) at peak (DeltaWatts=5.8+/-23.0, P=0.027), a less efficient ventilation (higher VE/VCO2 slope: 38.0+/-8.3 vs. 32.8+/-6.3, P<0.001), lower peak exercise tidal volume (1.49+/-0.36 L vs. 1.61+/-0.46 L, P=0.015) and higher peak respiratory rate (34+/-7/min vs. 31+/-6/min, P=0.002). In 33 patients, EOV disappeared during exercise, whereas in 45 patients EOV persisted. Fifty percent of EOV disappearing patients had an increase in the VO2/WL relationship after EOV regression, consistent with a more efficient oxygen delivery to muscles. No cardiopulmonary exercise test parameter was associated with the different behaviour of VO2/WL. The presence of EOV negatively influences exercise performance of chronic heart failure patients likely because of an increased cost of breathing. EOV disappearance during exercise is associated with a more efficient oxygen delivery in several cases.

Haller Index Does Not Predict Physiologic Impairment In Children And Adolescents With Pectus Excavatum.

Background: Pectus excavatum (PE) is a chest wall defect that may be associated with lung disease and exercise impairment. The Haller index (HI) is a marker of chest wall compression measured by chest CT and has been used as a marker of PE severity. Discordance between extent of cosmetic abnormality and clinical symptoms has been observed. PURPOSE: The study was designed to examine the relationship of HI and markers of pulmonary function and exercise performance. METHODS: Forty-one subjects with PE, 11F:30M, mean age 14.1 ± 3.9 years (5.4 - 22.8 yrs) underwent an evaluation including assessment of lung volume, spirometry, respiratory muscle strength, and exercise tolerance. Chest CTs were obtained with a HI measured per published standards. Values are expressed as mean ± standard deviation. Pulmonary function and exercise parameters are expressed as percent of predicted. Spearman correlation coefficients were measured. Significance was set as p<0.05. RESULTS: The total lung capacity (TLC) was 97.4 ± 16.9 % and forced vital capacity (FVC) was 97.2 ± 14.7%. Peak inspiratory and expiratory muscle strengths were reduced (PImax 78.5 ± 22.5; PEmax 64.2 ± 17.4%). Exercise tolerance was normal whether expressed as VO2 (88.2 ± 17.4%) or peak work capacity (PWC) (100.4 ± 18.1%). An impaired breathing reserve (VE/MVV: 85.2 ± 18.4), an elevated peak respiratory rate (58.1 ± 12.9), and elevated ventilatory equivalents at ventilatory threshold (VE/VO2: 34.2 ± 5.9; VE/VCO2: 33.2 ± 7.9) were observed. HI (4.2 ± 1.2) was weakly correlated to TLC (r=−0.36) and FVC (r=−0.51). No correlation was seen between HI and PImax, PEmax, PWC, VO2, RR, or VE/MVV. Discussion: While the classic description of PE includes lung restriction, our study did not demonstrate consistent restriction despite abnormal HI. There was a correlation between HI and lung volume. Total exercise performance appeared normal but was associated with impaired ventilatory reserves, impaired respiratory muscle strength, and breathing limitations. The HI did not appear to be associated with these abnormal findings. CONCLUSION: The HI appears to be associated with lung volume compromise. However, HI appears to be a poor predictor of associated physiologic impairment and does not replace the need for physiologic testing to determine the extent of compromise caused by the defect.

Laparoscopic Urinary Tract Surgery in Infants Weighing 6 kg or Less: Perioperative Considerations and Comparison to Open Surgery

Laparoscopic urinary tract surgery is rarely performed in small infants. We compared the safety, feasibility and outcome of laparoscopic urinary tract surgery in children weighing 6 kg or less with a weight matched cohort undergoing open urinary tract surgery. We performed a retrospective nonrandomized chart review comparing 17 infants weighing 6 kg or less who underwent laparoscopic urinary tract surgery beginning in 2005 with a weight matched historical group of 18 patients who had undergone open urinary tract surgery. We recorded procedures performed, operative times, blood loss, length of hospitalization, preoperative and postoperative hemoglobin and serum creatinine levels, analgesia requirements, complications and outcomes. Urine output during anesthesia was recorded and expressed as ml/kg per hour. We also recorded intraoperative changes in heart rate, mean arterial blood pressure, peak inspiratory pressure, respiratory rate, oxygen saturation, CO(2) and core body temperature. Estimated blood loss was minimal in all cases. Mean operative time +/- SD was 201 +/- 72 minutes in the laparoscopic group and 112 +/- 36 minutes in the open group (p <0.01). Patients undergoing laparoscopic surgery had lower intraoperative urine output but no changes in preoperative or postoperative serum creatinine levels. Mean postoperative hospitalization +/- SD was 2 +/- 1 days in the laparoscopic group and 3.2 +/- 2.18 days in the open group. Mean opioid requirement (morphine equivalent) +/- SD was higher in the open group, at 0.24 +/- 0.15 mg/kg, compared to the laparoscopic group, at 0.13 +/- 0.19 mg/kg. Operation related complications were diagnosed in 1 patient (6%) from the laparoscopic group and 2 patients (11%) from the open group. Laparoscopic urinary tract surgery can be performed safely in neonates and small infants with outcomes comparable to that of open surgery, with decreased analgesia requirements and faster recovery.

Transient tachypnea of the newborn: Predictive factor for prolonged tachypnea

Because there is a lack of well-established criteria, the aim of the present paper was to determine risk factors to predict the duration of tachypnea in transient tachypnea of the newborn (TTN). Data from 95 newborns with TTN were evaluated retrospectively. Clinical and laboratory findings were compared between patients in whom tachypnea lasted <72 h (group 1) or >72 h (group 2). Male gender, prematurity and delivery by cesarean section were the major risk factors for TTN. Parenteral furosemide had no effect on the clinical course. Peak respiratory rate (RRpeak) at the first 36 h was significantly higher in group 2 (P > 0.000). The cut-off for RRpeak during the first 36 h (RRpeak36) was 90/min and RRpeak36 > 90/min caused a 7.04-fold risk of prolonged tachypnea. White blood cell count and hematocrit levels were lower whereas duration of hospitalization and antibiotic treatment were longer in group 2. Assessment of RRpeak36 may be useful in predicting clinical course of TTN.

The role of procalcitonin in a decision tree for prediction of bloodstream infection in febrile patients

Bloodstream infection (BSI) in febrile patients is associated with high mortality. Clinical and laboratory variables, such as procalcitonin (PCT), may predict BSI and help decision-making concerning empirical treatment. This study compared two models for prediction of BSI, and evaluated the role of PCT vs. clinical variables, collected daily in 300 consecutive febrile inpatients, for 48 h after onset of fever. Multiple logistic regression (MLR) and classification and regression tree (CART) models were compared for discriminatory power and diagnostic performance. BSI was present in 17% of cases. MLR identified the presence of intravascular devices, nadir albumin and thrombocyte counts, and peak temperature, respiratory rate and leukocyte counts, but not PCT, as independent predictors of BSI. In contrast, a peak PCT level of >2.45 ng/mL was the principal discriminator in the decision tree based on CART. The latter was more accurate (94%) than the model based on MLR (72%; p <0.01). Hence, the presence of BSI in febrile patients is predicted more accurately and by different variables, e.g., PCT, in CART analysis, as compared with MLR models. This underlines the value of PCT plus CART analysis in the diagnosis of a febrile patient.

Evaluation of peak inspiratory pressure and respiratory rate during ventilation of an infant lung model with a self-inflating bag

To evaluate the peak inspiratory pressure and ventilation rate achieved by physicians when using a neonatal self-inflating bag on a lung model. Fifteen physicians ventilated full term and preterm infant lung simulators while the outcomes were captured by a ventilation monitor. Median peak pressures in cmH(2)O for full term and preterm lungs were 23 (interquartile range: 15-47) and 26 (interquartile range: 14-51), being less than 20 in 41.2 and 35.8% of the pressure curves analyzed, more than 40 in 29.7 and 33.6%, and between 27 and 33 cmH(2)O in 8.2 and 6.5% of the curves, respectively. Median ventilation rates were 45 (interquartile range: 36-57) and 48 (interquartile range: 39-55.5) cycles per minute, being more than 30 in 9.3 and 6.7% of pressure curves and more than 60 in 12 and 13.3% of pressure curves, for the full term and preterm lungs, respectively. The differences between these medians were not statistically significant. Ventilation rates achieved with the self-inflating bag were adequate in approximately 80% of pressure curves analyzed, but the physicians were unable to provide ventilation with minimal pressure variation, producing pressures that diverged from those defined by the neonatal resuscitation training course in 70% of the curves. This was irrespective of whether they were ventilating the lung model analogous to preterm or full term infant lungs.

Evaluation of peak inspiratory pressure, tidal volume and respiratory rate during ventilation of premature lambs using a self-inflating bag

To evaluate the peak inspiratory pressure, tidal volume and respiratory rate achieved during manual ventilation of premature lambs, using a self-inflating bag. In this descriptive, experimental study, five pairs of physicians, selected at random among 35 neonatologists working at a neonatal intensive care unit and with experience in the resuscitation of newborn infants, ventilated five intubated premature lambs using a self-inflating bag. Pressure and flow monitor signals were passed through a transducer and digitized for recording and analysis. Tidal volume and pressure curves were obtained from the integral of flow rate, at peak, during the last 50 seconds of every fifth minute, and analyzed. Median pressure was 39.8 (IQ(25-75%) 30.2-47.2) cmH(2)O; being below 20 in 1.1% of cases and above 40 in 49.1%. Seven out of 10 physicians produced more than six pressure peaks of over 40 cmH(2)O. Median tidal volume/kg was 17.8 (IQ(25-75%) 14.1-22.4) mL, being below 5 mL in 0.1% of cases and greater than or equal to 20 mL in 37.7%. All of the physicians propelled five or more ventilation cycles with tidal volume/kg of 20 mL or more. Respiratory rate was between 30 and 60 cycles/minute in 65.9% of cases, being below 30 in 6.8% of cases and over 60 in 27.3% of cases. There was major variation in peak inspiratory pressure and tidal volume/kg values, which were in many cases elevated, attaining levels that habitually cause biotrauma, while respiratory rates were adequate in the majority of cases.

Cerebellar fastigial nuclei activity during blood pressure challenges

The cerebellar fastigial nuclei (FN) assist in regulating compensatory responses to large blood pressure changes and show structural injury and functional impairment to cardiovascular challenges in syndromes with sleep-disordered breathing. The patterned time course of FN responses to elevation or lowering of blood pressure and location of responsive regions within the nuclei are unclear. We evaluated FN neural activity in six anesthetized rats using optical imaging procedures during elevation and lowering of arterial pressure by phenylephrine and nitroprusside, respectively. Hypertension diminished optical correlates of FN neural activity, while measures of activity increased to hypotension, with peak neural responses occurring 5-10 s later than peak blood pressure changes. Blood pressure responses were followed by heart rate changes, and peak respiratory rates developed even later, in close temporal proximity to FN activity patterns. Although overall topographical response trends were similar, regional patterns of altered neural activity appeared to both hypertension and hypotension. The extent of neural change was greater during recovery from hypertension than for hypotension at high-dose levels. Blood pressure levels saturated with increasing phenylephrine doses, while FN activity continued to decline. No saturation appeared in heart or respiratory rate trends. The findings suggest that the FN compensate for large blood pressure changes by sympathoexcitatory and inhibitory processes, which accompany late-developing somatic or respiratory adjustments.

Efficacy of nebulized furosemide in children with moderate attack of asthma

Bronchodilators are the most commonly used drugs for asthma. However, alternative treatment is necessary for those patients who experience adverse effects from bronchodilators. To investigate the efficacy of nebulized furosemide in children with moderate asthma exacerbations. A double-blind randomized, controlled trial involving three groups of children with moderate attack of asthma. Twenty children were enrolled in group A and received nebulized albuterol, 20 children in group B received nebulized furosemide and 19 children in group C received both albuterol and furosemide. Pulmonary function parameters, peak flow rates, respiratory rate, oxygen saturation and clinical scores were obtained before and after treatment. The maximum increases in FEV1 achieved were 21.1 +/- 4.6 %, 20.8 +/- 3.2 and 21.7 +/- 4.9 in groups A, B and C respectively. The differences between the groups were not significant. Maximum increase in FVC was 20.3 +/- 1.6, 22.5 +/- 5.8 % and 24.5 +/- 4.9 % in groups B and C respectively. The difference between the three groups was not statistically significant. With regards to peak expiratory flow rate (PEFR), the mean increase after treatment was 23.5 +/- 8.6% and 21.8 +/- 6.3% in groups A and B respectively. There was significant increase in PEFR in group C children (26.0 +/- 9.1%; p = 0.01). There was no statistical significant difference among the three groups regarding the improvement in respiratory rate, SaO2 and clinical scores. Combination of both furosemide and albuterol led to significant increase in peak flow rate but it did not significantly affect FEV1, FVC, FEF 25-75, respiratory rate, SaO2 or clinical scores as compared to other groups. There were no significant adverse effects from the three drugs used.

Exercise Capacity Deterioration in Patients With COPD: Longitudinal Evaluation Over 5 Years

Background Although exercise capacity is an important outcome measure in patients with COPD, its longitudinal course has not been analyzed in comparison to the change in pulmonary function. Purpose To examine how exercise capacity would deteriorate over time in patients with COPD, and what factors would contribute to it. Methods A total of 137 male outpatients with moderate-to-very-severe COPD were examined. The average age was 69.0 ± 6.6 years (± SD), and the mean postbronchodilator FEV1 was 45.9 ± 15.4% predicted. Progressive cycle ergometry and pulmonary function testing were performed at entry, and every 6 months thereafter over 5 years. Due to the presence of missing data, a mixed-effect model analysis was then used to estimate the longitudinal changes in various clinical parameters. Results Peak oxygen uptake ( V ˙ o2), peak minute ventilation ( V ˙ e), and peak tidal volume (Vt) during exercise declined significantly over time (p < 0.0001), which was no less rapid than the deterioration in FEV1. The mean decline rates for peak V ˙ o2 were 32 ± 60 mL/min/yr and 0.5 ± 1.0 mL/min/kg/yr. Multiple regression analysis revealed that the changes in peak V ˙ e, peak Vt, and peak respiratory rates were significant predictors for the change in peak V ˙ o2. Conclusion We demonstrated clear evidence of measurable and progressive deterioration in exercise capacity in COPD patients, which was no less rapid than the decline in airflow limitation. Dynamic ventilatory constraints during exercise also deteriorated over time, which most significantly contributed to this exercise capacity deterioration. In addition to pulmonary function, the longitudinal follow-up of exercise capacity is important not to miss the overall deterioration in COPD. Although exercise capacity is an important outcome measure in patients with COPD, its longitudinal course has not been analyzed in comparison to the change in pulmonary function. To examine how exercise capacity would deteriorate over time in patients with COPD, and what factors would contribute to it. A total of 137 male outpatients with moderate-to-very-severe COPD were examined. The average age was 69.0 ± 6.6 years (± SD), and the mean postbronchodilator FEV1 was 45.9 ± 15.4% predicted. Progressive cycle ergometry and pulmonary function testing were performed at entry, and every 6 months thereafter over 5 years. Due to the presence of missing data, a mixed-effect model analysis was then used to estimate the longitudinal changes in various clinical parameters. Peak oxygen uptake ( V ˙ o2), peak minute ventilation ( V ˙ e), and peak tidal volume (Vt) during exercise declined significantly over time (p < 0.0001), which was no less rapid than the deterioration in FEV1. The mean decline rates for peak V ˙ o2 were 32 ± 60 mL/min/yr and 0.5 ± 1.0 mL/min/kg/yr. Multiple regression analysis revealed that the changes in peak V ˙ e, peak Vt, and peak respiratory rates were significant predictors for the change in peak V ˙ o2. We demonstrated clear evidence of measurable and progressive deterioration in exercise capacity in COPD patients, which was no less rapid than the decline in airflow limitation. Dynamic ventilatory constraints during exercise also deteriorated over time, which most significantly contributed to this exercise capacity deterioration. In addition to pulmonary function, the longitudinal follow-up of exercise capacity is important not to miss the overall deterioration in COPD.

Frailty, morbidity and survival

Frailty, as a reflection of decreased physical reserve rather than disability, is assessed by various functional tests rather than by specific disease burden. We investigated association of measures of frailty to disease outcomes and survival in a population-based study of Midwestern adults. The markers of frailty we evaluated were: time to walk a measured course (gait-time), handgrip strength, peak respiratory flow rate, ability to stand from a sitting position without using arms, and best corrected visual acuity. A history of cardiovascular disease, cancer, and hypertension were obtained. Data were collected at the third examination (1998–2000) of the Beaver Dam Eye Study cohort ( n = 2962). Follow-up for mortality occurred up to 4 1 2 years after the 1998–2000 examinations. Markers of frailty were significantly associated with age. Values in the highest quartile (slowest) of gait-time, lowest quartile of peak expiratory flow rate, lowest quartile of handgrip strength, inability to stand from sitting in one try (those not in a wheelchair), and visual impairment were combined in an index to denote a general description of frailty. The range of the index was 0 (no frailty) to 5 (maximum frailty). Greater frailty was significantly associated with cardiovascular disease and hypertension. Frailty was associated with poorer survival over an interval of 4 1 2 years after adjusting for age, sex, hypertension, diabetes, and cardiovascular disease. Greater frailty was associated with greater likelihood of concurrent medical conditions and with decreased survival.

Fruit development and ripening in Barbados cherry, Malpighia emarginata DC.

Barbados cherry fruit shows a biphasic pattern of growth whether monitored on a diameter or weight basis. Each growth phase was of about 2 weeks duration with weight gains of equal magnitude but with most of the size increase occurring in the first phase. Pyrene growth paralleled that of the whole fruit. Cell division was limited to the first week of fruit development and horticultural maturity was reached when fruit showed colour break (18 days post-anthesis). Barbados cherry is climacteric with a very high peak respiratory rate (900 ml CO 2 kg −1 h −1) but a low rate of peak ethylene production (3 μl C 2H 4 kg −1 h −1), the former consistent with its high perishability.

Percutaneous extracorporeal arteriovenous carbon dioxide removal improves survival in respiratory distress syndrome: A prospective randomized outcomes study in adult sheep

Objective: Arteriovenous carbon dioxide removal (AVCO2R) uses a simple arteriovenous shunt for CO2 removal to minimize barotrauma/volutrauma from mechanical ventilation. We performed a prospective randomized outcomes study of AVCO2R in our new, clinically relevant model of respiratory distress syndrome. Methods: Adult sheep (n = 18) received an LD50 severe smoke inhalation and 40% third-degree burn. When respiratory distress syndrome developed (PaO2/FIO2 < 200 at 40 to 48 hours), animals were randomized to the AVCO2R (n = 9) or sham group (n = 9) for 7 days. Ventilator management protocols mandated reductions in minute ventilation, first tidal volume to peak inspiratory pressure less than 30 cm H2O, then respiratory rate when PaCO2 was less than 40 mm Hg. PaO2 was kept above 60 mm Hg by adjusting FIO2. When FIO2 was 0.21, animals were weaned. Results: The study required 2946 animal-hours of critical care with 696 AVCO2R hours. One died in each group during model development. AVCO2R flow from 820 mL/min to 970 mL/min (11% to 14% cardiac output) removed CO2 at a rate of 92 to 116 mL/min (mean 103 mL/min; 93%-97% of CO2 production). Heart rate, mean arterial pressure, cardiac output, and pulmonary arterial wedge pressure remained relatively constant. Within 48 hours, AVCO2R allowed significant ventilator reductions versus baseline in the following measurements: tidal volume (420 to 270 mL), peak inspiratory pressure (25 to 14 cm H2O), minute ventilation (13 to 5 L/min), respiratory rate (26 to 16 breaths/min), and FIO2 (0.88 to 0.35). Ventilator-free days with AVCO2R were 3.9 versus 0.2 (P <.01) for sham animals, and ventilator-dependent days with AVCO2R were 2.4 versus 6.2 (P <.01) for the 3 sham survivors. All 8 AVCO2R animals and 3 of 8 sham animals survived 7 days after randomization. Conclusions: Percutaneous AVCO2R achieved significant reduction in airway pressures, increased ventilator-free days, decreased ventilator-dependent days, and improved survival in a sheep model of respiratory distress syndrome. (J Thorac Cardiovasc Surg 2001;121:542-51)

Prediction of shock in febrile medical patients with a clinical infection.

Shock in the course of fever is likely caused by septic shock. Because septic shock carries a high mortality rate, early recognition could benefit the patient. We tried to predict the development of shock in medical patients with fever and a clinical infection, on the basis of clinical and microbiological information, and to evaluate the role therein of systemic inflammatory response syndrome (SIRS) criteria: abnormal body temperature, tachycardia, tachypnea, and abnormal white blood cell counts. Prospective observational study. Department of Internal Medicine at a university hospital. Patients were 212 consecutive medical patients with newly onset fever (temperature, >38.0 degrees C axillary or >38.3 degrees C rectally) and a clinical source of infection. Of the 212 patients enrolled, 14 developed shock (i.e., a decrease in systolic arterial blood pressure of >40 mm Hg) during a maximum follow-up period of 7 days after inclusion. In univariate analyses, advanced age, prior urogenital disease, an abdominal source, nosocomial infections, and bacteremia predisposed patients to shock (p < .05). For clinical variables, obtained daily for 2 days after inclusion, a low performance (p < .001), the peak respiratory rate (p < .05), the peak heart rate (p < .05), the nadir score on the Glasgow Coma Scale (p < .005), the peak and nadir white blood cell counts (p < .005), and the nadir albumin (p < .01) and peak creatinine concentrations in blood (p < .001) predicted shock development. In multivariate analysis, the presence of bacteremia, the peak respiratory rate, the nadir Glasgow Coma Scale score, and the peak white blood cell count positively and the peak erythrocyte sedimentation rate negatively contributed to prediction of shock development. In contrast, SIRS had less predictive value, mainly because of lack of predictive value of peak heart rate and temperature in multivariate models. In febrile medical patients with a clinical infection, the development of shock involves an interaction between circulating microbial products and the host response, which can be recognized clinically by variables easily obtained at the bedside and partly different from the set used to define SIRS.

Oxygen uptake efficiency slope: an index of exercise performance and cardiopulmonary reserve requiring only submaximal exercise

OBJECTIVESWe sought to evaluate, in adults, the efficacy of the Oxygen Uptake Efficiency Slope (OUES), an index of cardiopulmonary functional reserve that can be based upon a submaximal exercise effort.BACKGROUNDMaximal oxygen uptake (O2 max), the most reliable measure of exercise capacity, is seldom attained in standard exercise testing. The OUES, which relates oxygen uptake to total ventilation during exercise, was proposed by Baba and coworkers (7) in a study of pediatric cardiac patients. They felt this submaximal index of cardiopulmonary reserve might be more practical than O2 max and more appropriate than the commonly used peak oxygen consumption (O2 peak).METHODSTreadmill exercise tests with simultaneous respiratory gas measurement were performed in 998 older subjects free of clinically recognized cardiovascular disease and 12 male patients with congestive heart failure. During incremental exercise, oxygen uptake was plotted against the logarithm of total ventilation, and the OUES was determined.RESULTSThe OUES, when calculated only from the first 75% of the exercise test, differed by 1.9% from the OUES calculated from 100% of exercise time in subjects with a peak respiratory exchange rate ≥1.10. On serial tests the OUES was less variable than exercise duration or O2 peak. It correlated strongly with O2 max, with forced expiratory volume in 1 s and negatively with a history of current smoking. The OUES declined linearly with age in both women and men. A small sample of patients with congestive heart failure had OUES values much lower than those of older subjects without cardiovascular disease.CONCLUSIONSThe OUES is an objective, reproducible measure of cardiopulmonary reserve that does not require a maximal exercise effort. It integrates cardiovascular, musculoskeletal and respiratory function into a single index that is largely influenced by pulmonary dead space ventilation and exercise-induced lactic acidosis.

Immunological parameters and respiratory functions in patients suffering from atopic bronchial asthma after intravenous treatment with salmon calcitonin

This study reports the effect of salmon calcitonin on airway function and peripheral blood parameters in asthmatic subjects. The premise for the study is that calcitonin is given to asthmatics that require systemic corticosteroids as a way to counter problems with calcium balance and osteoporosis, and that it has an immunosuppressive effect. Salmon calcitonin (100 IU) was administered to 18 patients with atopic bronchial asthma, and the following spirometric parameters were evaluated: forced vital capacity (FVC), forced expiratory volume in the first second (FEV 1), peak respiratory flow rate (PEFR) and forced expiratory flow rates at 25%, 50% and 75% of the forced vital capacity (FEF 25%, FEF 50% and FEF 75%). Calcitonin significantly decreased the levels of FVC and FEV 1 by 20 min after starting the infusion. The effect of 500 mg aminophylline, used as a reference drug in this study, was much more profound, with a significant increase in all investigated parameters. Also, the effect of salmon calcitonin on some immune parameters (white blood cell count, number of eosinophils, serum levels of immunoglobulins IgG, IgM and IgA, and serum levels of lymphocytes subpopulations CD3, CD4, CD8 and CD19) was determined in another group of 30 patients suffering from atopic bronchial asthma. Calcitonin at a dose of 100 IU/day subcutaneously for 3 days did not alter the immune parameters studied, thus rendering it safe for such and similar treatment schedules in a variety of medical conditions.

The Effect of Heliox in Acute Severe Asthma: A Randomized Controlled Trial

To evaluate the effect of heliox on airflow obstruction and dyspnea in patients with acute severe asthma. A prospective, randomized, controlled study. A university hospital. Twenty-three patients presenting to the emergency department with acute severe asthma were randomized to receive 70%/30% heliox or 30% oxygen. Peak expiratory flow (PEF), dyspnea score, heart rate, respiratory rate (RR), and BP were measured at baseline and 20, 120, 240, 360, and 480 min after starting the test gas. After baseline, the PEF was measured by using the gas that was randomized to the treatment program. In the first 20 min, there was a 58.4% increase in percent predicted PEF (%PEF) in the heliox group (p<0.001), whereas there was only a 10.1% increase in %PEF for the oxygen group (p>0.1). Eighty-two percent of the heliox group had >25% improvement in %PEF at 20 min, whereas only 17% of the oxygen group did (p<0.01). The next significant improvement in %PEF in the heliox group occurred at 480 min. At the end of the study in the heliox group, the PEF did not significantly (p>0.1) change immediately after the heliox was discontinued (270.6 to 264.2 L/min). In the heliox group in the first 20 min, there was a significant decrease in dyspnea score and RR (p<0.05), but there were no further significant improvements for the rest of the study. In the oxygen group, no variables significantly improved until 360 min. Heliox rapidly improves airflow obstruction and dyspnea in patients with acute severe asthma and may be useful as a therapeutic bridge until the corticosteroid effect occurs.

A Case of Menstruation-Associated Asthma: Treatment With Oral Contraceptives

A menstrual rhythm has been documented for exacerbations of asthma, which may have important clinical relevance to the patient with severe asthma. We report the case of a 26-year-old patient with menstruation-associated asthma who showed a dramatic response to oral contraceptives. It was noted that falls in peak respiratory flow rate coincided with ovulation. We concluded that oral contraceptive therapy is useful in this particular group of asthmatic patients.