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Objective:  We aimed to determine the composite maternal hemorrhagic outcome (CMHO) among individuals with and without hypertensive disorders of pregnancy (HDP), stratified by disease severity. Additionally, we investigated the composite neonatal adverse outcome (CNAO) among individuals with HDP who had postpartum hemorrhage (PPH) versus did not have PPH., Study Design:  Our retrospective cohort study included all singletons who delivered at a Level IV center over two consecutive years. The primary outcome was the rate of CMHO, defined as blood loss ≥1,000 mL, use of uterotonics, mechanical tamponade, surgical techniques for atony, transfusion, venous thromboembolism, intensive care unit admission, hysterectomy, or maternal death. A subgroup analysis was performed to investigate the primary outcome stratified by (1) chronic hypertension, (2) gestational hypertension and preeclampsia without severe features, and (3) preeclampsia with severe features. A multivariable regression analysis was performed to investigate the association of HDP with and without PPH on a CNAO which included APGAR <7 at 5 minutes, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, seizures, neonatal sepsis, meconium aspiration syndrome, ventilation >6 hours, hypoxic-ischemic encephalopathy, or neonatal death., Results:  Of 8,357 singletons, 2,827 (34%) had HDP. Preterm delivery <37 weeks, induction of labor, prolonged oxytocin use, and magnesium sulfate usage were more common in those with versus without HDP ( p  < 0.001). CMHO was higher among individuals with HDP than those without HDP (26 vs. 19%; adjusted relative risk [aRR] = 1.11, 95% CI: 1.01-1.22). In the subgroup analysis, only individuals with preeclampsia with severe features were associated with higher CMHO ( n  = 802; aRR = 1.52, 95% CI: 1.32-1.75). There was a higher likelihood of CNAO in individuals with both HDP and PPH compared to those with HDP without PPH (aRR = 1.49, 95% CI: 1.06-2.09)., Conclusion:  CMHO was higher among those with HDP. After stratification, only those with preeclampsia with severe features had an increased risk of CMHO. Among individuals with HDP, those who also had a PPH had worse neonatal outcomes than those without hemorrhage., Key Points: · Individuals with HDP had an 11% higher likelihood of CMHO.. · After stratification, increased CMHO was limited to those with preeclampsia with severe features.. · There was a higher likelihood of CNAO in those with both HDP and PPH compared to HDP without PPH.., Competing Interests: None declared., (Thieme. All rights reserved.)

Objective:  This study aimed to compare maternal and neonatal outcomes between labor induction versus cesarean delivery (CD) without labor among nulliparous individuals with class III obesity (body mass index [BMI] ≥40 kg/m 2 )., Study Design:  A retrospective cohort study of all nulliparous singleton deliveries at ≥37 weeks with a BMI of ≥40 kg/m 2 at delivery between March 2020 and February 2022. We excluded individuals with spontaneous labor, fetal malformations, and stillbirths. The primary outcome was a composite of maternal mortality and morbidity, including infectious and hemorrhagic morbidity. The secondary outcome was a neonatal composite. A subgroup analysis evaluated patients with a BMI of ≥50 kg/m 2 . Another subgroup analysis compared outcomes between CD without labor and an indicated CD following induction. A multivariable logistic regression was applied. For adjustment, we used possible confounders identified in a univariate analysis., Results:  Among 8,623 consecutive deliveries during the study period, 308 (4%) met the inclusion criteria. Among them, 250 (81%) underwent labor induction, and 58 (19%) had a CD without labor. The most common indications for CD without labor were fetal malpresentation (26; 45%), suspected macrosomia (8; 14%), and previous myomectomy (5; 9%). Indicated CD occurred in 140 (56%) of the induced individuals, with the two leading indications being labor arrest (87; 62%) and non-reassuring fetal heart rate tracing (51; 36%). The rates of composite maternal morbidity (adjusted odds ratio [aOR] = 2.14, 95% confidence interval [CI]: 0.64-7.13) and composite neonatal morbidity (aOR = 3.62, 95% CI: 0.42-31.19) did not differ following a CD without labor compared to labor induction. The subgroup analyses did not demonstrate different outcomes between groups., Conclusion:  Among nulliparous individuals with class III obesity at term who underwent induction, more than 50% had indicated CD; the rate of short-term maternal and neonatal morbidity, however, did not differ between labor induction and CD without labor., Key Points: · The rate of unplanned CD among those who underwent labor induction was relatively high (56.0%).. · Outcomes did not differ between those who underwent CD without labor and those who were induced.. · Outcomes also did not differ between those who underwent CD without labor and those with CD in labor.., Competing Interests: None declared., (Thieme. All rights reserved.)

Background: Guidelines promote stratification for the risk for postpartum hemorrhage among parturients, although the evidence for the associated differential morbidity among the groups remains inconsistent among published reports., Objective: Using the California Maternal Quality Care Collaborative schema modified by the American College of Obstetrics and Gynecology, we compared the composite maternal hemorrhagic outcome and the composite neonatal adverse outcome among singletons who were categorized after delivery by the researchers as low-, medium-, or high-risk for postpartum hemorrhage. We hypothesized that the composite outcomes would be significantly different among the individuals in the different 3-tiered categories., Study Design: This was a retrospective cohort study of all singleton parturients with a gestational age of at least 14 weeks who delivered at a single site within 1 year. The composite maternal hemorrhagic outcome included any of the following: estimated blood loss ≥1000 mL, use of uterotonics (excluding prophylactic oxytocin) or Bakri balloon, surgical management of postpartum hemorrhage, blood transfusion, hysterectomy, thromboembolism, admission to the intensive care unit, or maternal death. The composite neonatal adverse outcome included Apgar score <7 at 5 minutes, birth injury, bronchopulmonary dysplasia, intraventricular hemorrhage, neonatal seizure, sepsis, ventilation > 6 hrs., brachial plexus palsy, hypoxic-ischemic encephalopathy, or neonatal death. Multivariable Poisson regression models with robust error variance were used to estimate the adjusted relative risks with 95% confidence intervals., Results: Of the 4544 deliveries in the study period, 4404 (96.7%) met the inclusion criteria, and among them, 1745 (39.6%) were categorized as low, 1376 (31.2%) as medium, and 1283 (29.1%) as high risk. Overall, 941 (21.4%) participants experienced the composite maternal hemorrhagic outcome with 285 (16.4%) of those being in the low-risk group, 319 (23.2%) in the medium-risk group, and 337 (26.3%) in the high-risk group. Among all parturients, 95.7% in the low-, 89.4% in the medium-, and 85.3% in the high-risk group neither had an estimated blood loss or a quantified blood loss ≥1000 mL nor were transfused. After multivariable adjustment and when compared with the low-risk group, there was a significantly higher risk for the composite maternal hemorrhagic outcome in the medium-risk group (adjusted relative risk, 1.23; 95% confidence interval, 1.05-1.43) and in the high-risk group (adjusted relative risk, 1.51; 95% confidence interval, 1.31-1.75). Overall, 366 newborns (8.4%) developed the composite neonatal adverse outcome with 76 (4.2%) in of those being in the low-risk group, 153 (11.3%) in the medium-risk group, and 140 (11.1%) in the high-risk group. After multivariable adjustment and when compared with the low-risk group, there were no significant differences in the composite neonatal adverse outcome in the medium- (adjusted relative risk, 1.27; 95% confidence interval, 0.97-1.68) or the high-risk group (adjusted relative risk, 1.29; 95% confidence interval, 0.98-1.68)., Conclusion: Although 8 of 10 parturients categorized as high risk neither had blood loss ≥1000 mL nor underwent transfusion, the risk stratification provides information regarding the composite maternal hemorrhagic outcome., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: Obesity is a risk factor for endometrial hyperplasia (EH), endometrial intraepithelial neoplasia (EIN), and early type 1 endometrial cancer (EC) in 70%-90% of patients and is often a significant contributor to overall morbidity and mortality due to comorbidities. In 2011, bariatric surgery (BS) with lifestyle modification was identified as an intervention for reduction in overall mortality as well as risk for gynecologic cancers (Tsui et al., 2021). Our aim was to assess awareness of obesity as a risk factor and understanding of BS in an underinsured obese patient population with EC or EH., Method: This IRB-approved survey was distributed to patients with type I EC or EH within the past 5 years and a BMI >30. Questions addressed demographics, health habits, cancer and obesity awareness, as well as benefits and concerns about undergoing BS. Information was provided about dietary requirements after BS, and then interest in BS was surveyed., Results: 61.2% of surveyed patients were interested in bariatric surgery for weight loss after receiving education about the procedure. Interest in bariatric surgery was correlated with higher BMI, higher ideal and comfortable weight loss in pounds and higher estimated weight loss that could be obtained with bariatric surgery. Additionally, patients who were interested in BS had better understanding of the risks of obesity with cancer overall., Conclusion: Obese patients with history of EC/EIN/EH are aware of hazards associated with excess weight and understand the relationship between EC/EIN/EH diagnosis and obesity, and overall are very interested in BS as a modality to improve their health., Competing Interests: Declaration of Competing Interest none to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: To delineate risk factors for adverse outcomes among those who underwent cesarean delivery (CD) for non-reassuring fetal heart rate tracing (NRFHT) and ascertain whether neonatal or maternal morbidity can be predicted accurately., Methods: The Consortium on Safe Labor Database was utilized for this secondary analysis. Inclusion criteria were non-anomalous, singleton gestations between 37.0 and 41.6 weeks who underwent CD for NRFHT. Composite adverse neonatal outcomes (CANO) included Apgar <5 at 5 min, seizures, mechanical ventilation, sepsis, intraventricular hemorrhage, necrotizing enterocolitis or neonatal death. Composite adverse maternal outcomes (CAMO) included endometritis, blood transfusion, wound complication, admission to intensive care unit, thromboembolism, hysterectomy or death. Bivariable analysis and multivariable Poisson regression were used to identify risk factors independently associated with adverse outcomes. Receiver operating characteristic (ROC) curves were created to evaluate the predictive value of the models for adverse outcomes., Results: Of 228,438 births in the database, 7310 individuals (3.7%) met inclusion criteria. Among this cohort, CANO occurred 3.8% of the time. CANO was less common among people over 35 years (9.8% versus 18.4% p  < .01) but was more common among those with at least high-school education (15.3% versus 11.2%; p  < .01), varying by ethnicity ( p  < .01). CAMO occurred in 3.4% and was less common among those undergoing induction of labor (37.3% versus 49.4%; p  < .01) and more common among those with clinical chorioamnionitis (8.4% versus 4.3%; p  < .01). The area under the curve (AUC) for ROC curve to identify CANO was 0.63 implying a limited ability to predict neonatal adverse outcomes. The AUC for identifying women with maternal adverse outcomes was 0.69 also indicating a moderate prediction ability., Conclusions: Among singletons between 37 and 41 weeks who labored, the rate of CD for NRFHT was about 3.7% and among them CANO occurred in 3.8%. While risk factors for adverse neonatal outcomes following CD for NRFHT are identifiable, they do not suffice to predict them.

Objective: Platinum-based chemotherapy and bevacizumab is the standard treatment for stage IVB cervical cancer. When metastases resolve, the benefit of radiating the primary tumor is unclear. We investigate the effect of pelvic radiation on PFS following chemotherapy and bevacizumab in stage IVB cervical cancer., Methods: This is a retrospective series of 29 patients with stage IVB cervical cancer treated with platinum-based chemotherapy and bevacizumab. 3 subgroups were evaluated: definitive pelvic radiation, palliative radiation, and no radiation. The primary outcome was the mean PFS. Progression was determined radiographically. Kaplan-Meier method and the log-rank test for equality analyzed OS and PFS., Results: The median OS was 38.4 months. 11 patients (38%) received definitive radiation, 9 (31%) received palliative and 9 (31%) received no radiation. 7/8 in the palliative group, 7/10 who received no radiation and all in the definitive group experienced progression. The median PFS was 7.5 months and not statistically different (p = 0.62). The median OS was not attained in the definitive group, was 23 months [19.6, -] for the palliative group and 19 months [24.9-45.4] for the no radiation group (p = 0.13). OS was higher in patients receiving definitive radiation vs all others (median OS survival not reached vs 6.6 months, p = 0.04). No difference in PFS between those receiving definitive radiation vs others (12 months vs 5.1 months p = 0.32)., Conclusion: Definitive radiation is associated with improved survival among in stage IVB cervical cancer treated with chemotherapy and bevacizumab. This association could be due to treatment, patient, or disease factors associated with improved oncologic outcomes. In absence of higher-level data, shared decision-making with consideration for comorbidities and performance status should be employed., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)

Objective: Little is known about prevalence, risk factors, rate of treatment, or adverse outcomes associated with intrapartum hypertension. Thus, our objective was to describe these findings., Study Design: This was a retrospective study of laboring term gestations with no history of hypertensive disorders. Intrapartum blood pressures were reviewed, and women were subdivided based on blood pressures: normal (<140 mm Hg systolic and <90 mm Hg diastolic), mild hypertension (140-159 or 90-109), and severe hypertension (≥ 160 or ≥ 110). Groups were compared using chi-square test and analysis of variance., Results: A total of 724 women were studied during 4 months: 248 (34%) had mild and 69 (10%) had severe hypertension. Severe hypertensives were more likely to be nulliparous, obese, or have received an epidural or oxytocin. There were no cases of eclampsia, stroke, or pulmonary edema in severe hypertensives (95% confidence interval, 0-5). Despite severely elevated pressures, only 4/69 (6%) patients received intravenous antihypertensive therapy, and 3 (4%) required medications at discharge., Conclusion: One in 3 women exhibits mild hypertension and 1 in 10 develop severe hypertension in labor. Only 6% of patients received treatment for severe blood pressures. This study highlights lack of treatment of hypertension in labor and further investigation into causes and outcomes of intrapartum elevations of blood pressures., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Although supplemental oxygen (SO 2 ) is routinely administered to laboring gravidas, benefits and harms are not well studied., Objective: This article compares strategies of liberal versus indicated SO 2 therapy during labor on cesarean delivery (CD) rate and neonatal outcomes., Study Design: A controlled, before-and-after trial of laboring women with term, singleton pregnancies. During an initial 8-week period, maternal SO 2 was administered at the discretion of the provider followed by an 8-week period where SO 2 was to be given only for protocol indications., Results: Our study included 844 women. There was no difference in number of women receiving SO 2 (53% liberal vs. 50% indicated; p  = 0.33). For those receiving SO 2 , there was no difference in SO 2 duration (median, 89 minutes [interquartile range, 42-172] vs. 87 minutes [36-152]; p  = 0.42). There were no differences in overall CD rate (20% vs. 17%; p  = 0.70), CD for nonreassuring fetal status, or use of intrauterine resuscitative measures. There were more 5-minute APGAR < 7 in the indicated group, but no difference in umbilical artery pH < 7.1 or neonatal intensive care unit (NICU) admission., Conclusion: Approximately half of women receive SO 2 intrapartum regardless of a strategy of liberal or indicated oxygen use. There were no clinically significant differences in outcomes between strategies., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Interior Least Terns (Sternula antillarum) (ILT) are colonial, fish-eating birds that breed within active channels of large sand bed rivers of the Great Plains and in the Lower Mississippi Valley. Multipurpose dams, irrigation structures, and engineered navigation systems have been present on these rivers for many decades. Despite severe alteration of channels and flow regimes, regulation era floods have remained effective at maintaining bare sandbar nesting habitat on many river segments and ILT populations have been stable or expanding since they were listed as endangered in 1985. We used ILT breeding colony locations from 2002 to 2012 and dispersal information to identify 16 populations and 48 subpopulations. More than 90% of ILT and >83% of river km with suitable nesting habitat occur within the two largest populations. However, replicate populations remain throughout the entire historical, geophysical, and ecological range of ILT. Rapid colonization of anthropogenic habitats in areas that were not historically occupied suggests metapopulation dynamics. The highest likelihood of demographic connectivity among ILT populations occurs across the Southern Plains and the Lower Mississippi River, which may be demographically connected with Least Tern populations on the Gulf Coast. Paired ecological and bird population models are needed to test whether previously articulated threats limit ILT population growth and to determine if management intervention is necessary and where. Given current knowledge, the largest sources of model uncertainty will be: (1) uncertainty in relationships between high flow events and subsequent sandbar characteristics and (2) uncertainty regarding the frequency of dispersal among population subunits. We recommend research strategies to reduce these uncertainties.

Objective: A short-term isometric exercise protocol was tested in ten hypertensive individuals to determine its efficacy as a high blood pressure-reducing intervention., Design: The study was a prospective case study of 10 hypertensive individuals (8 men, 2 woman, mean age = 52 + 5 years) who underwent six weeks of isometric exercise training (three sessions/week)., Methods: Blood pressure, blood lipids and markers of oxidative stress were monitored before, during and following the isometric intervention. Electron spin resonance spectroscopy was used to directly measure radicals in the blood samples., Results: After six weeks, systolic blood pressure decreased an average 13 mm Hg (p < 0.05) from a mean blood pressure of 146 to 133 mm Hg, a level that is below the usual 140 mm Hg hypertension threshold. Blood lipids were unchanged, but markers of oxidative stress were affected, with a dramatic decrease in exercise-induced oxygen centered radicals (-266%), (p < 0.05) and an increased resting whole blood glutathione:oxidized glutathione (+61%) in hypertensive adults following six weeks of isometric exercise., Conclusion: Six weeks of isometric exercise training was effective in lowering systolic but not diastolic blood pressure in pre-hypertensive and hypertensive individuals, and enhanced antioxidant protection is a likely underlying mechanism.

The interaction between genes and environment can influence cardiovascular disease (CVD). This 16 month study investigated if genes associated with cardiovascular (CV) regulation were expressed differently in animals having: 1) no access to physical activity or exercise (SED), 2) access to hour-long, twice weekly activity (PA), and 3) access every-other-day to a running wheel (EX). Out of 31,000 genes, a CV subset comprising 44 genes was investigated. Ten genes from this subset were expressed differently in EX compared with SED, and 34 genes were expressed differently in PA compared with SED (p<0.05). Total cholesterol (70+/-8 vs. 101+/-9 mg dl(-1)), triglycerides (104+/-8 vs. 127+/-4 mg dl(-1)), resting systolic blood pressure (130+/-3 vs. 141+/-3 mmHg), mean arterial pressure (110+/-2 vs. 120+/-2 mmHg) and heart rate (380+/-6 vs. 405+/-9 beats min(-1)) were lower in EX compared with SED (p<0.05), but intracellular adhesion molecule levels did not differ among groups. Mean gene expressions for Gja1, Fdft1, Edn1, Cd36, and Hmgb2 differed in animals according to access to physical activity. These genes play roles in heart rate, cholesterol biosynthesis, blood pressure, cell adhesion, and transcription and neurogenesis regulation, respectively. In conclusion, a total of 44 CV genes were expressed differently in SED compared to PA and EX; and SED showed more physiological evidence of CVD.

Voluntary and forced exercise decrease morbidity and mortality in laboratory animals. Caloric restriction has similar effects on health and unique benefits on life span. Nonetheless, in most experiments, animals do not have access to physical activity and are fed ad libitum (AL). We hypothesized that with regular access to either unlimited running wheel exercise (EX) or limited physical activity (PA), key biomarkers of health would be enhanced enough to counter some consequences of a sedentary AL lifestyle. This 16-month study compared body weight, tumor number and size, tissue lesions, oxidative stress, and reactive stress in (1) sedentary animals with no access to physical activity (SED); (2) animals with access to hour-long, twice weekly activity in a large box (PA); and (3) animals with access every other day to a running wheel (EX). At the end of the study, EX body weight was 8-9% lower than PA and SED. In addition, EX had no kidney lesions versus 50% in PA and SED, and had smaller tumor size (10+/-2 vs. 14+/-4 and 30+/-4 mm). Exhaustive exercise lowered glutathione/oxidized glutathione ratio in EX and PA, but in SED, the ratio was depressed even in resting animals. In all treatments, prolactin (PRL) levels were lower in resting animals than in acutely exercised animals. In conclusion, EX had the most favorable health biomarkers while SED had the least. PA did not confer gross health benefits different than the SED group, but was biochemically more similar to EX animals.

Swim training alters cardiovascular, sympathoadrenal, and endocrine responses to hemorrhage in borderline hypertensive rats (BHR). The effects of 10, 20, and 30% blood volume hemorrhages on cardiovascular, sympathoadrenal, and endocrine function in swim-trained (T; 2 h/day, 5 day/wk for 10-12 wk) and age-matched, untrained, sedentary, control (UT) borderline hypertensive rats (BHR) were assessed. Heart rate (HR) in UT BHR was significantly greater during the baseline (rest) period than T BHR. HR increased slightly from baseline in both groups after 10% hemorrhage but was significantly decreased in both groups after 20 and 30% hemorrhages. The decrease was eliminated by atropine (1 mg/kg iv). Systolic (SBP) and diastolic (DBP) blood pressures decreased significantly after 20 and 30% hemorrhages in both T and UT BHR but were not different between the groups at these times. Plasma norepinephrine levels were significantly increased above baseline after 20 and 30% hemorrhages in UT BHR and were significantly greater in UT BHR than T BHR after 30% hemorrhage. Plasma glucose levels increased significantly after 30% hemorrhage in both groups but were significantly greater in UT BHR than T BHR. Both plasma norepinephrine and plasma epinephrine levels showed strong positive correlations with plasma glucose. After 20 and 30% hemorrhages, plasma insulin levels were unchanged in T BHR but were significantly decreased in UT BHR. Plasma insulin levels were significantly less in UT than T BHR after 30% hemorrhage. These results suggest that swim training alters the effect that hemorrhage exerts on endocrine and sympathoadrenal function in BHR.(ABSTRACT TRUNCATED AT 250 WORDS)

The present study assessed the effects of 40 min of tail shock stress (1-s shock, 0.2 mA every 30 s) on renal and cardiovascular function in swim-trained (T), water-immersed (IM), and untrained (UT) borderline hypertensive rats (BHR). T BHR swam for 2 h/day 5 days/wk for 10-12 wk, whereas IM BHR on the same schedule were placed in water at neck level and were not permitted to swim. Age-matched sedentary controls were paired one each with the exercise group (group 1) and the immersion group (group 2). Heart rate was significantly greater in UT than in T BHR (P = 0.09) during baseline (rest). Heart rate responses during stress were not different between UT and IM BHR (group 2). Systolic and diastolic blood pressures during stress and recovery were not different between UT BHR and T or IM BHR. Urine flow rate was significantly increased from baseline during the first 20 min of stress in UT and IM BHR only. Changes in glomerular filtration rate were not consistent across studies. Renal blood flow decreased significantly from baseline during tail shock stress in UT but not T BHR. Plasma glucose levels were significantly increased above baseline during the second 20 min of stress in UT BHR only and were significantly greater than those in the T BHR. Plasma insulin levels in UT BHR were significantly decreased from baseline during tail shock stress and recovery but were unchanged from baseline in T BHR. These observations suggest that swim training independent of water immersion alters the effect that stress exerts on renal and cardiovascular function in BHR, which results in better fluid and electrolyte conservation in T BHR.

Both rhythmic and "resistive" (weight lifting) exercise training can produce modest decreases in resting blood pressure. The next logical point along an exercise continuum consisting of different proportions of rhythmic and isometric efforts is a strictly isometric effort. The purpose of these studies was to assess the effects of isometric, handgrip exercise training on resting blood pressure. To avoid the extreme pressor responses elicited by fatiguing isometric efforts, the isometric exercise training used in this study consisted of brief handgrip contractions separated by rest periods. Modest repeated rises in systolic and diastolic pressures therefore served as the putative stimuli for training adaptations in resting blood pressures. Human subjects in study 1 trained with four, 2-min isometric handgrip contractions with 3-min rests between contractions. The intensity of the contractions was equal to 30% of their maximal effort for each day. The bouts of isometric exercise were performed three times per week for 8 wk. Study 2 training consisted of four contractions of 50% of maximum effort held for a duration of 45 s with 1-min rests. These were performed 5 d.wk-1 for 5 wk. In Study 1, all eight trained subjects had a significant decline in both systolic and diastolic resting blood pressures, with group averages of 12.5 and 14.9 mm Hg, respectively. Seven matched control subjects who did not train had no change in resting pressures. In study 2, subjects were trained in their home or workplace and experienced significant mean declines in resting systolic and diastolic pressures of 9.5 and 8.9 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

The transient and steady-state cardiopulmonary responses to combined rhythmic (R) and isometric (I) exercise were examined in nine subjects. Isometric exercise at 30% maximal voluntary contraction (MVC) was started 1.5 min prior to either a 50% or 75% maximal oxygen uptake (VO2max) cycle ride and continued for 1.5 min into the 10-min R. Systolic (Pas) and diastolic (P(ad)) blood pressure, heart rate (fc), inspired ventilation volumes (VI), and oxygen uptake (VO2) were recorded every 30 s throughout each experiment. Responses to I effort alone were recorded for comparison with experiments in which the combined exercises were performed during the first 1.5 min when R had not yet begun. Pas responses in the first 1.5 min of I (no R) showed the typical rapid linear increase. Addition of the R effort further increased Pas to levels which remained nearly constant (steady state) throughout R. R alone produced a slower Pas increase to approximately the same steady-state levels as those of the combined R and I exercise. For P(ad), the linear increase which occurred during the first 1.5 min of I was attenuated with the superimposition of R. Following cessation of I, P(ad) fell rapidly during continued R to levels not different from experiments with R alone. The fc during I alone increased slightly. As I continued, the onset of the R induced a further rapid increase in fc to levels not different from R alone. The VI showed a similar response to fc. VO2 during I alone did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

A rhythmic (R) and an isometric (I) exercise were performed separately and in combination to assess their additive effects on arterial systolic (P(as)) and diastolic (P(ad)) blood pressures, heart rate (fc), and minute ventilation (VI). The isometric effort consisted of a 40% maximal voluntary handgrip contraction (MVC) performed for a duration of 80% of a previously determined 40% MVC fatiguing effort. The R effort consisted of a 13-min cycle effort at 75% maximum oxygen consumption (VO2max). For the combined efforts, I was performed starting simultaneously with or ending simultaneously with R. Data on nine subjects yield statistically significant evidence (P less than 0.05) that the effects of I and R are not additive for the following three cases: (1) P(as) when I and R are ended simultaneously (I alone = 4.9, SEM 0.5 kPa increase; R alone = no significant change from steady state; I + R = 1.2, SEM 0.4 kPa increase), (2) P(ad) when I and R are started simultaneously (I alone = 4.1, SEM 0.4 kPa increase; R alone = 0.7, SEM 0.3 kPa decrease; I + R = 1.9, SEM 0.4 kPa increase), and (3) P(ad) when I and R are ended simultaneously (I alone = 4.1, SEM 0.4 kPa increase; R alone = 0.3, SEM 0.5 kPa decrease; I + R = 0.8, SEM 0.3 kPa increase). For all other variables and cases, there is not sufficient evidence to conclude that the effects of I and R are not additive. We conclude that R and I exercises do not invariably produce strictly additive cardiopulmonary responses.(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of this study was to determine the stability of the function describing subjects' magnitude estimates of added inspiratory resistive loads following short-term exposure (STE) to a high but nonfatiguing, inspiratory load. Four inspiratory resistive loads (8.9-35.7 cmH2O X l-1 X s) were presented twice each in random order. Subjects were asked to estimate load magnitude by force of handgrip. Perceptual performance was quantified using Stevens power law, psi = k phi n, where psi is the subject's estimate, k is a constant, and phi is the peak mouth pressure developed against the load. The exponent n represents the slope of the line in the plot of log psi vs. log phi. After a 2-min period in which subjects were required to generate 80% of their maximum inspiratory pressure against a high resistance, the load estimation protocol was repeated. Estimates were significantly reduced compared to control; however, there was no significant difference in the exponent for magnitude functions between conditions. Similar results were obtained in a second parallel experiment involving magnitude estimation of weights lifted by the elbow flexors. The results suggest plasticity in the mechanism(s) subserving sensation of added loads to breathing and that such plasticity is a general feature of sensation arising from nonrespiratory muscles as well.

The effect of background loading on magnitude estimation of added elastic and resistive inspiratory loads was determined. An analogous study involving estimation of the heaviness of weights in the hand was also performed. Perceptual performance was assessed using Stevens' power law psi = k phi n, where psi is the subjective magnitude, phi is the peak mouth pressure generated with an inspiratory load or the weight of the load in grams for the heaviness estimation, and the exponent n characterizes perceptual performance. The value of n was determined for the control and background conditions for each study. The results for both inspiratory loading studies and the heaviness estimation experiment indicate that background loading is associated with a significant increase in the exponent for magnitude estimation (P less than 0.05). Adjustment of the stimulus scale by subtracting the difference in peak mouth pressures generated during resting breathing between control and background-loaded conditions for the inspiratory loading studies, or the weight of the background load in the heaviness estimation experiment, converted the exponents obtained under background-loaded conditions to values that were not significantly different from those for control (P greater than 0.05). These results are consistent with the theory suggesting that an increase in detection threshold, produced by the background load, is responsible for the increase in exponent for magnitude estimation.

The effect of restricting chest expansion on the detection of resistive loads added to inspiration was assessed in 6 healthy male subjects. Restriction was accomplished using an adjustable chest clamping device. Load detection scores obtained with and without chest clamping were plotted against deltaR and the Weber Fraction (deltaR/Ro), where deltaR is the added load and Ro is the initial resistive load (i.e. subject's R plus minimal R of the apparatus). Results indicate that restricting chest expansion does not alter the ability of healthy subjects to detect added inspiratory resistive loads. It is concluded that perception of such loads is not dependent upon sensory information from the chest wall.

1. Six male subjects performed simulataneous static (hand-grip) and rhythmic (bicycle ergometer) exercises while their respiratory responses were measured. 2. Oxygen consumption increased with the intensity of rhythmic work load, with a modest additional oxygen consumption accompanying the addition of static effort during the rhythmic exercise. 3. Minute ventilation (VE) increased directly with rhythmic exercise, but increased disproportionately to the metabolic need when static effort was added. The mean increment of VE elicited by the static exercise influence was nearly constant at 20 l/min, regardless of the rhythmic load present. 4. Possible reflex mechanisms which result in disruption of the normally well-matched ventilation and metabolic oxygen demands whenever static effort is present are discussed.

Changes in blood pressure, intrathoracic pressure, heart rate and the electromyographic activity of various muscle groups were determined while nine male subjects performed 15-s L-1 straining maneuvers at four spine-to-thigh angles (70, 84, 94, and 105 degrees) and two seatback angles (30 and 60 degrees). There was no significant difference between the changes in these variables due to the different body positions. At the onset of the L-1, arterial pressure immediately increased to 195 +/- 5 mm Hg, but fell progressively during the next 5 s to 160 +/- 5 mm Hg. It remained constant during the next 5 s of the maneuver and then recovered to 180 +/- mm Hg during the last 5 s of the maneuver. Esophageal pressure followed essentially the same pattern of response, but heart rate progressively increased during the entire L-1. No one muscle group was utilized more than another. Inflation of an anti-G suit to 4 PSI had no effect on the variables measured. Generation of high arterial pressures during L-1 maneuvers is transitory and not affected either positively or negatively by altering subject body position.

Previous studies of the latencies for the detection of inspiratory resistive (R) and elastic (E) loads revealed that R loads were detected earlier in the loaded breath than E loads (Respir. Physiol. 34: 267--77, 1978). These results suggested that the load information generated by R and E loads have different temporal patterns. We hypothesized that these differences might provide a mechanism for subjects to accurately discriminate between R and E loads and secondly, that the R and E load sensations perceived by subjects should have different temporal characteristics. To test these hypotheses we studied six healthy subjects in a two-part study. In this first, two levels of R and E loads (near threshold and 4--5 times threshold) were randomly presented for single inspirations separated by 3--6 unloaded breaths for a total of 10 presentations each. Subjects indicated detection and type of load perceived by pressing R or E marker buttons. In the second part, using the same loading protocol, subjects squeezed a hand grip dynamometer to express the pattern of perceived load sensation. Results indicate that subjects cannot discriminate between near-threshold R and E load but can discriminate between R and E loads 4--5 times threshold with considerable accuracy. Mean grip responses show that perceived load sensations arise earlier and reach maximum values sooner during R loaded breaths. Grip responses are consistent with the previously reported differences in R and E detection latencies and support the hypothesis that load discrimination is mediated by differences in the temporal pattern of load information generated during R and E loaded breaths.

The purpose of this investigation was to measure changes in transdiaphragmatic pressure (Pdi) developed during graded elastic (E) and resistive (R) loaded breaths and to correlate the emergence of such changes with the load-dependent alterations in latency for detection (Tdet). Five healthy adults were studied using three protocols, i.e., graded E, graded R, and graded R in the presence of elevated background R. In each protocol, loads were added for single inspirations, 10 times in random order and separated by three to five unloaded breaths. Subjects pressed a signal marker as soon as loads were detected. Inspiratory flow (VI), inspired volume (VI), mouth pressure, and Pdi of loaded breaths and the preceding unloaded breaths were recorded and computer averaged. Patterns of VI and VI were not altered prior to detection of the smallest added E and R loads but decreased with the higher loads. Group mean patterns of Pdi showed graded increases during loaded breaths. Augmentation of Pdi preceded Tdet and occurred earlier as Tdet decreased with graded E and R loads. Elevating the background R delayed both Tdet of added R and the augmentation of Pdi. Results are consistent with the hypothesis that load-induced changes in diaphragmatic tension may play a sensory role in detection of inspiratory loads.

Previous research indicates that fatiguing static exercise causes hyperventilation and a decrease of end-tidal CO2 partial pressure PETCO2. The objectives of this study were 1) to examine the changes in pattern of breathing during static exercise, and 2) to define the isocapnic ventilatory response. Six healthy males were studied once a week at one of three levels of static handgrip exercise: 15, 25, or 30% maximum voluntary contraction (MVC) was sustained for 5 min while holding PETCO2 constant or allowing it to run free. During 25 and 30% MVC, we observed 1) progressive increases in mean tidal volume (VT), inspiratory ventilation (VI), VT/TI, heart rate (HR), and arterial BP, 2) increased breath-to-breath variability of VT, 3) no significant changes in respiratory frequency (f), and 4) progressive decreases in PETCO2. Keeping PETCO2 constant at preexercise levels did not change the pattern or magnitude of the ventilatory response to exercise. The time course and magnitude of the subjects' perceived effort resembled the time course and magnitude of the ventilatory response. The variability of VT during the response to static exercise suggests an element of control instability. The identical ventilatory responses during hypocapnic and isocapnic conditions may result from the slow response of the central chemoreceptors; an overriding influence of muscle afferents; and/or increased central command arising with fatigue.