Cardiopulmonary performance testing using a robotics-assisted tilt table: Feasibility assessment in able-bodied subjects

BACKGROUND: Robotics-assisted tilt table technology was introduced for early rehabilitation of neurological patients. It provides cyclical stepping movement and physiological loading of the legs. The aim of the present study was to assess the feasibility of this type of device for peak cardiopulmonary performance testing using able-bodied subjects. METHODS: A robotics-assisted tilt table was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Feasibility assessment focused on: (i) implementation (technical feasibility), and (ii) responsiveness (was there a measurable, high-level cardiopulmonary reaction?). For responsiveness testing, each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/min in female subjects and 8 W/min in males. RESULTS: 11 able-bodied subjects were included (9 male, 2 female; age 29.6 ± 7.1 years: mean ± SD). Resting oxygen uptake (O_{2}) was 4.6 ± 0.7 mL/min/kg and O_{2}peak was 32.4 ± 5.1 mL/min/kg; this mean O_{2}peak was 81.1% of the predicted peak value for cycle ergometry. Peak heart rate (HRpeak) was 177.5 ± 9.7 beats/min; all subjects reached at least 85% of their predicted HRpeak value. Respiratory exchange ratio (RER) at O_{2}peak was 1.02 ± 0.07. Peak work rate) was 61.3 ± 15.1 W. All subjects reported a Borg CR10 value for exertion and leg fatigue of 7 or more. CONCLUSIONS: The robotics-assisted tilt table is deemed feasible for peak cardiopulmonary performance testing: the approach was found to be technically implementable and substantial cardiopulmonary responses were observed. Further testing in neurologically-impaired subjects is warranted.

Investigation of robotics-assisted tilt table technology for cardiopulmonary exercise testing in stroke patients

Due to the lack of exercise testing devices that can be employed in stroke patients with severe disability, the aim of this PhD research was to investigate the clinical feasibility of using a robotics-assisted tilt table (RATT) as a method for cardiopulmonary exercise testing (CPET) and exercise training in stroke patients. For this purpose, the RATT was augmented with force sensors, a visual feedback system and a work rate calculation algorithm. As the RATT had not been used previously for CPET, the first phase of this project focused on a feasibility study in 11 healthy able-bodied subjects. The results demonstrated substantial cardiopulmonary responses, no complications were found, and the method was deemed feasible. The second phase was to analyse validity and test-retest reliability of the primary CPET parameters obtained from the RATT in 18 healthy able-bodied subjects and to compare the outcomes to those obtained from standard exercise testing devices (a cycle ergometer and a treadmill). The results demonstrated that peak oxygen uptake (V'O2peak) and oxygen uptake at the submaximal exercise thresholds on the RATT were ̴20% lower than for the cycle ergometer and ̴30% lower than on the treadmill. A very high correlation was found between the RATT vs the cycle ergometer V'O2peak and the RATT vs the treadmill V'O2peak. Test-retest reliability of CPET parameters obtained from the RATT were similarly high to those for standard exercise testing devices. These findings suggested that the RATT is a valid and reliable device for CPET and that it has potential to be used in severely impaired patients. Thus, the third phase was to investigate using the RATT for CPET and exercise training in 8 severely disabled stroke patients. The method was technically implementable, well tolerated by the patients, and substantial cardiopulmonary responses were observed. Additionally, all patients could exercise at the recommended training intensity for 10 min bouts. Finally, an investigation of test-retest reliability and four-week changes in cardiopulmonary fitness was carried out in 17 stroke patients with various degrees of disability. Good to excellent test-retest reliability and repeatability were found for the main CPET variables. There was no significant difference in most CPET parameters over four weeks. In conclusion, based on the demonstrated validity, reliability and repeatability, the RATT was found to be a feasible and appropriate alternative exercise testing and training device for patients who have limitations for use of standard devices.

Respostas cardiopulmonares agudas de mulheres no treinamento de força

OBJETIVE: Investigate the cardiopulmonary responses of one strength training session in young women. METHOD: Twenty-three women aged between 18 and 29 years participated in this study. All the volunteers were submitted to the following tests: cardiopulmonary and one-repetition maximum (1-RM). The strength training protocol had emphasis on muscular hypertrophy, three sets from eight to twelve repetitions under 70% of 1-RM, with a one minute thirty-second break between sets. During the training session, the cardiopulmonary variables were measured with a metabolic gas analyzer and a telemetry module. RESULTS: The results of the oxygen consumption in the training session were from 8.43 + 1.76 ml/kg/min and of the heart rate of 108.08 + 15.26 bpm. The results of the oxygen consumption and of the heart rate in the training were lower (p < 0.01) than in the ventilatory threshold and of the oxygen consumption and the heart rate reserves. CONCLUSION: The obtained data show that the present protocol of strength training provided low overload to the cardiopulmonary system of young women.

Aerobic capacity and skeletal muscle function in children with asthma

Background Peripheral muscle strength and endurance are decreased in patients with chronic pulmonary diseases and seem to contribute to patients' exercise intolerance. However, the authors are not aware of any studies evaluating peripheral muscle function in children with asthma. It seems to be implied that children with asthma have lower aerobic fitness, but there are limited studies comparing the aerobic capacity of children with and without asthma. The present study aimed to evaluate muscle strength and endurance in children with persistent asthma and their association with aerobic capacity and inhaled corticosteroid consumption. Methods Forty children with mild persistent asthma (MPA) or severe persistent asthma (SPA) (N=20 each) and 20 children without asthma (control group) were evaluated. Upper (pectoralis and latissimus dorsi) and lower (quadriceps) muscle strength and endurance were assessed, and cardiopulmonary exercise testing was performed. Inhaled corticosteroid consumption during the last 6 and 24 months was also quantified. Results Children with SPA presented a reduction in peak oxygen consumption (VO(2)) (28.2 +/- 8.1 vs 34.7 +/- 6.9 ml/kg/min; p<0.01) and quadriceps endurance (43.1 +/- 6.7 vs 80.9 +/- 11.9 repetitions; p<0.05) compared with the control group, but not the MPA group (31.5 +/- 6.1 ml/kg/min and 56.7 +/- 47.7 repetitions respectively; p>0.05). Maximal upper and lower muscle strength was preserved in children with both mild and severe asthma (p>0.05). Finally, the authors observed that lower muscle endurance weakness was not associated with reductions in either peak VO(2) (r=0.22, p>0.05) or corticosteroid consumption (r=-0.31, p>0.05) in children with asthma. Conclusion The findings suggest that cardiopulmonary exercise and lower limb muscle endurance should be a priority during physical training programs for children with severe asthma.

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 +/- 0.9 Hz, vibration at 10.5 +/- 2.3 Hz, and shaking at 6.2 +/- 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 +/- 5.0, 0.7 +/- 0.3, and 1.4 +/- 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and forces generated by these techniques was 80% of variance in shaking force (P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1) can be consistently performed by physiotherapists; 2) are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3) caused no significant hemodynamic effects.

Étude de la réponse aiguë à l'exercice intermittent à haute intensité chez le patient coronarien

L'entraînement par intervalles à haute intensité est plus efficace que l'entraînement continu d’intensité modérée pour améliorer la consommation maximale d’oxygène (VO2max) et le profil métabolique des patients coronariens. Cependant, il n’y a pas de publications pour appuyer la prescription d’un type d’exercice intermittent (HIIE) spécifique dans cette population. Nous avons donc comparé les réponses aiguës cardio-pulmonaires de quatre sessions différentes d’exercice intermittent dans le but d’identifier l’exercice optimal chez les patients coronariens. De manière randomisée, les sujets participaient aux sessions d’HIIE, toutes avec des phases d’exercice à 100% de la puissance maximale aérobie (PMA), mais qui variaient selon la durée des phases d’exercice et de récupération (15s ou 1 min) et la nature de la récupération (0% de la PMA ou 50% de la PMA). Chaque session était réalisée sous forme de temps limite et l’exercice était interrompu après 35 minutes. En considérant l’effort perçu, le confort du patient et le temps passé au-dessus de 80% de VO2max, nous avons trouvé que l’exercice optimal consistait à alterner des courtes phases d’exercice de 15s à 100% de la PMA avec des phases de 15s de récupération passive. Ensuite, nous avons comparé les réponses physiologiques de l’HIIE optimisé avec un exercice continu d’intensité modérée (MICE) iso-calorique chez des patients coronariens. En considérant les réponses physiologiques, l’aspect sécuritaire (aucune élévation de Troponin T) et l’effort perçu, le protocole HIIE est apparu mieux toléré et plus efficace chez ces coronariens. Finalement, une simple session d’HIIE n’induit pas d’effets délétères sur la paroi vasculaire, comme démontré avec l’analyse des microparticules endothéliales. En conclusion, l’exercice intermittent à haute intensité est un mode d'entraînement prometteur pour les patients coronariens stables qui devrait faire l’objet d’autres études expérimentales en particulier pour les patients coronariens ischémiques.

Étude des réponses physiologiques aiguës à l’exercice intermittent de haute intensité chez le patient insuffisant cardiaque

L’optimisation de l’exercice par intervalles de haute intensité (EIHI) chez les patients insuffisants cardiaques (IC) n’a jamais été étudiée auparavant. Nous avons comparé les réponses cardio-pulmonaires aiguës lors de 4 différents EIHI dans le but de trouver le protocole optimisé chez les patients IC. Les patients IC étaient aléatoirement alloués à 4 sessions d’EIHI. Chaque phase d’exercice était à une intensité de 100% de la puissance aérobie maximale (PAM), mais de différentes durées (30s ou 90s) et de type de récupération (passive ou active). Chaque protocole d’EIHI durait un maximum de 30 minutes ou jusqu’à épuisement. Considérant le temps total d’exercice, l’adhérence, une perception d’effort moins élevée, le confort du patient ainsi que des temps similaires passés à un haut pourcentage du VO2pic, le mode avec intervalles courts (30s) et récupération passive s’est avéré être le protocole d’EIHI optimisé chez ces patients. Suite à cette étude, nous avons voulu comparer les réponses cardio-pulmonaires aiguës d’un exercice continu d’intensité modéré (ECIM) par rapport à celles de l’EIHI optimisé de dépense énergétique équivalente chez les patients IC. L’objectif de cette étude était de comparer les réponses cardio-pulmonaires, l’adhérence, la perception de l’effort, l’inflammation et les biomarqueurs cardiaques. Comparativement à l’ECIM, l’adhérence, l’efficience et la tolérance étaient plus élevées lors de l’EIHI optimisé chez les patients IC tout en produisant un stimulus physiologique important. L’EIHI n’a causé aucune arythmie significative ou d’effets délétères sur l’inflammation (CRP), le BNP et la nécrose myocardique (C-TnT) chez les patients IC. L’EIHI semble être un mode d’exercice prometteur et devrait être considéré lors de la réadaptation cardiaque chez les patients IC.

Comparaison des réponses physiologiques lors d’un exercice incrémental maximal sur vélo immergé et sur terrain sec : aspects biomécaniques, cardiopulmonaires et hémodynamiques.

L’exercice en immersion dans l'eau peut générer des réponses hémodynamiques et cardiorespiratoires différentes à celles de l’exercice sur terraine sec. Cependant, aucune étude n’a comparé ces réponses sur vélo aquatique (VA) à celles sur vélo sur terrain sec (VS) à une même puissance mécanique externe (Pext). À cet égard, le premier travail de cette thèse visait, d’abord, à trouver les équivalences de Pext lors du pédalage sur VA en immersion à la poitrine par rapport au VS au laboratoire, en considérant que cela restait non déterminé à ce jour. Une équation de mécanique des fluides fut utilisée pour calculer la force déployée pour le système de pédalage (pales, leviers, pédales) et des jambes à chaque tour de pédale. Ensuite, cette force totale a été multipliée par la vitesse de pédalage pour estimer la Pext sur VA. Ayant trouvé les équivalences de Pext sur VA et VS, nous nous sommes fixés comme objectif dans la deuxième étude de comparer les réponses hémodynamiques et cardiorespiratoires lors d'un exercice maximal progressif sur VS par rapport au VA à une même Pext. Les résultats ont montré que le VO2 (p<0.0001) et la différence artério-veineuse (C(a-v)O2) (p<0.0001) étaient diminués lors de l’exercice sur VA comparativement à celui sur VS. Parmi les variables hémodynamiques, le volume d’éjection systolique (VES) (p˂0.05) et le débit cardiaque (Qc) (p˂0.05) étaient plus élevés sur VA. En plus, on nota une diminution significative de la fréquence cardiaque (FC) (p˂0.05). Étant donné qu’à une même Pext les réponses physiologiques sont différentes sur VA par rapport à celles sur VS, nous avons effectué une troisième étude pour établir la relation entre les différentes expressions de l'intensité relative de l'exercice (% du VO2max,% de la FCmax,% du VO2 de réserve (% de VO2R) et % de la FC réserve (% FCR)). Les résultats ont démontré que la relation % FCR vs % VO2R était la plus corrélée (régression linéaire) et la plus proche de la ligne d’identité. Ces résultats pourraient aider à mieux prescrire et contrôler l’intensité de l'exercice sur VA pour des sujets sains. Finalement, une dernière étude comparant la réactivation parasympathique après un exercice maximal incrémental effectué sur VA et VS en immersion au niveau de la poitrine a montré que la réactivation parasympathique à court terme était plus prédominante sur VA (i,e. t, delta 10 à delta 60 et T30, p<0.05). Cela suggérait, qu’après un exercice maximal sur VA, la réactivation parasympathique à court terme était accélérée par rapport à celle après l'effort maximal sur VS chez de jeunes sujets sains. En conclusion, nous proposons une méthode de calcul de la puissance mécanique externe sur VA en fonction de la cadence de pédalage. Nous avons démontré que pendant l’exercice sur VA les réponses hémodynamiques et cardiorespiratoires sont différentes de celles sur VS à une même Pext et nous proposons des équations pour le calcul du VO2 dans l’eau ainsi qu’une méthode pour la prescription et le contrôle de l’exercice sur VA. Finalement, la réactivation parasympathique à court terme s’est trouvée accélérée après un effort maximal incrémental sur VA comparativement à celle sur VS.

Intensity and physiological responses to the 6-minute walk test in middle-aged and older adults: a comparison with cardiopulmonary exercise testing

The 6-minute walk test (6MWT) is a simple field test that is widely used in clinical settings to assess functional exercise capacity. However, studies with healthy subjects are scarce. We hypothesized that the 6MWT might be useful to assess exercise capacity in healthy subjects. The purpose of this study was to evaluate 6MWT intensity in middle-aged and older adults, as well as to develop a simple equation to predict oxygen uptake ( V ˙ O 2 ) from the 6-min walk distance (6MWD). Eighty-six participants, 40 men and 46 women, 40-74 years of age and with a mean body mass index of 28±6 kg/m2, performed the 6MWT according to American Thoracic Society guidelines. Physiological responses were evaluated during the 6MWT using a K4b2 Cosmed telemetry gas analyzer. On a different occasion, the subjects performed ramp protocol cardiopulmonary exercise testing (CPET) on a treadmill. Peak V ˙ O 2 in the 6MWT corresponded to 78±13% of the peak V ˙ O 2 during CPET, and the maximum heart rate corresponded to 80±23% of that obtained in CPET. Peak V ˙ O 2 in CPET was adequately predicted by the 6MWD by a linear regression equation: V ˙ O 2 mL·min-1·kg-1 = -2.863 + (0.0563×6MWDm) (R2=0.76). The 6MWT represents a moderate-to-high intensity activity in middle-aged and older adults and proved to be useful for predicting cardiorespiratory fitness in the present study. Our results suggest that the 6MWT may also be useful in asymptomatic individuals, and its use in walk-based conditioning programs should be encouraged.

Respiratory and cardiovascular responses to hypoxia in the Australian lungfish

Simultaneous measurements of pulmonary blood flow (qPA), coeliacomesenteric blood flow (qCoA), dorsal aortic blood pressure (PDA), heart rate (fH) and branchial ventilation frequency (fv) were made in the Australian lungfish, /Neoceratodus forsteri, /during air breathing and aquatic hypoxia. The cho­linergic and adrenergic influences on the cardiovascular system were investigated during normoxia using pharmacological agents, and the presence of catecholamines and serotonin in different tissues was investi­gated using histochemistry. Air breathing rarely occurred during normoxia but when it did, it was always associated with increased pulmonary blood flow. The pulmonary vasculature is influenced by both a cho­linergic and adrenergic tonus whereas the coeliacomesenteric vasculature is influenced by a β-adrenergic vasodilator mechanism. No adrenergic nerve fibers could be demonstrated in /Neoceratodus /but catecholamine-containing endothelial cells were found in the atrium of the heart. In addition, serotonin-­immunoreactive cells were demonstrated in the pulmonary epithelium. The most prominent response to aquatic hypoxia was an increase in gill breathing frequency followed by an increased number of air breaths together with increased pulmonary blood flow. It is clear from the present investigation that /Neoceratodus /is able to match cardiovascular performance to meet the changes in respiration during hypoxia.

Predicting Outcome after Cardiopulmonary Arrest in Therapeutic Hypothermia Patients: Clinical, Electrophysiological and Imaging Prognosticators

INTRODUCTION: Predicting outcome in comatose survivors of cardiac arrest is based on data validated by guidelines that were established before the era of therapeutic hypothermia. We sought to evaluate the predictive value of clinical, electrophysiological and imaging data on patients submitted to therapeutic hypothermia. MATERIALS AND METHODS: A retrospective analysis of consecutive patients receiving therapeutic hypothermia during years 2010 and 2011 was made. Neurological examination, somatosensory evoked potentials, auditory evoked potentials, electroencephalography and brain magnetic resonance imaging were obtained during the first 72 hours. Glasgow Outcome Scale at 6 months, dichotomized into bad outcome (grades 1 and 2) and good outcome (grades 3, 4 and 5), was defined as the primary outcome. RESULTS: A total of 26 patients were studied. Absent pupillary light reflex, absent corneal and oculocephalic reflexes, absent N20 responses on evoked potentials and myoclonic status epilepticus showed no false-positives in predicting bad outcome. A malignant electroencephalographic pattern was also associated with a bad outcome (p = 0.05), with no false-positives. Two patients with a good outcome showed motor responses no better than extension (false-positive rate of 25%, p = 0.008) within 72 hours, both of them requiring prolonged sedation. Imaging findings of brain ischemia did not correlate with outcome. DISCUSSION: Absent pupillary, corneal and oculocephalic reflexes, absent N20 responses and a malignant electroencephalographic pattern all remain accurate predictors of poor outcome in cardiac arrest patients submitted to therapeutic hypothermia. CONCLUSION: Prolonged sedation beyond the hypothermia period may confound prediction strength of motor responses.

Three short perioperative infusions of n-3 PUFAs reduce systemic inflammation induced by cardiopulmonary bypass surgery: a randomized controlled trial.

BACKGROUND: Fish oil (FO) has antiinflammatory effects, which might reduce systemic inflammation induced by a cardiopulmonary bypass (CPB). OBJECTIVE: We tested whether perioperative infusions of FO modify the cell membrane composition, inflammatory responses, and clinical course of patients undergoing elective coronary artery bypass surgery. DESIGN: A prospective randomized controlled trial was conducted in cardiac surgery patients who received 3 infusions of 0.2 g/kg FO emulsion or saline (control) 12 and 2 h before and immediately after surgery. Blood samples (7 time points) and an atrial biopsy (during surgery) were obtained to assess the membrane incorporation of PUFAs. Hemodynamic data, catecholamine requirements, and core temperatures were recorded at 10-min intervals; blood triglycerides, nonesterified fatty acids, glucose, lactate, inflammatory cytokines, and carboxyhemoglobin concentrations were measured at selected time points. RESULTS: Twenty-eight patients, with a mean ± SD age of 65.5 ± 9.9 y, were enrolled with no baseline differences between groups. Significant increases in platelet EPA (+0.86%; P = 0.0001) and DHA (+0.87%; P = 0.019) were observed after FO consumption compared with at baseline. Atrial tissue EPA concentrations were higher after FO than after control treatments (+0.5%; P < 0.0001). FO did not significantly alter core temperature but decreased the postoperative rise in IL-6 (P = 0.018). Plasma triglycerides increased transiently after each FO infusion. Plasma concentrations of glucose, lactate, and blood carboxyhemoglobin were lower in the FO than in the control group on the day after surgery. Arrhythmia incidence was low with no significant difference between groups. No adverse effect of FO was detected. CONCLUSIONS: Perioperative FO infusions significantly increased PUFA concentrations in platelet and atrial tissue membranes within 12 h of the first FO administration and decreased biological and clinical signs of inflammation. These results suggest that perioperative FO may be beneficial in elective cardiac surgery with CPB. This trial was registered at clinicaltrials.gov as NCT00516178.

Cardiorespiratory and Cardiac Autonomic Responses to 30-15 Intermittent Fitness Test in Team Sport Players

Buchheit, M, Al Haddad, H, Millet GP, Lepretre, PM, Newton, M, and Ahmaidi, S. Cardiorespiratory and cardiac autonomic responses to 30-15 Intermittent Fitness Test in team sport players. J Strength Cond Res 23(1): xxx-xxx, 2009-The 30-15 Intermittent Fitness Test (30-15IFT) is an attractive alternative to classic continuous incremental field tests for defining a reference velocity for interval training prescription in team sport athletes. The aim of the present study was to compare cardiorespiratory and autonomic responses to 30-15IFT with those observed during a standard continuous test (CT). In 20 team sport players (20.9 +/- 2.2 years), cardiopulmonary parameters were measured during exercise and for 10 minutes after both tests. Final running velocity, peak lactate ([La]peak), and rating of perceived exertion (RPE) were also measured. Parasympathetic function was assessed during the postexercise recovery phase via heart rate (HR) recovery time constant (HRRtau) and HR variability (HRV) vagal-related indices. At exhaustion, no difference was observed in peak oxygen uptake (&OV0312;o2peak), respiratory exchange ratio, HR, or RPE between 30-15IFT and CT. In contrast, 30-15IFT led to significantly higher minute ventilation, [La]peak, and final velocity than CT (p < 0.05 for all parameters). All maximal cardiorespiratory variables observed during both tests were moderately to well correlated (e.g., r = 0.76, p = 0.001 for &OV0312;o2peak). Regarding ventilatory thresholds (VThs), all cardiorespiratory measurements were similar and well correlated between the 2 tests. Parasympathetic function was lower after 30-15IFT than after CT, as indicated by significantly longer HHRtau (81.9 +/- 18.2 vs. 60.5 +/- 19.5 for 30-15IFT and CT, respectively, p < 0.001) and lower HRV vagal-related indices (i.e., the root mean square of successive R-R intervals differences [rMSSD]: 4.1 +/- 2.4 and 7.0 +/- 4.9 milliseconds, p < 0.05). In conclusion, the 30-15IFT is accurate for assessing VThs and &OV0312;o2peak, but it alters postexercise parasympathetic function more than a continuous incremental protocol.

Cardiorespiratory responses during and after water exercise in pregnant and non-pregnant women

PURPOSE: to compare the blood pressure and oxygen consumption (VO2) responses between pregnant and non-pregnant women, during cycle ergometer exercise on land and in water. METHODS: ten pregnant (27 to 29 weeks of gestation) and ten non-pregnant women were enrolled. Two cardiopulmonary tests were performed on a cycle ergometer (water and land) at the heart rate corresponding to VO2, over a period of 30 minutes each. Exercise measurements consisted of recording blood pressure every five minutes, and heart rate and VO2 every 20 seconds. Two-way ANOVA was used and α=0.05 (SPSS 17.0). RESULTS: there was no difference in cardiovascular responses between pregnant and non-pregnant women during the exercise. The Pregnant Group demonstrated significant differences in systolic (131.6±8.2; 142.6±11.3 mmHg), diastolic (64.8±5.9; 74.5±5.3 mmHg), and mean blood pressure (87.0±4.1; 97.2±5.7 mmHg), during water and land exercise, respectively. The Non-pregnant women Group also had a significantly lower systolic (130.5±8.4; 135.9±8.7 mmHg), diastolic (67.4±5.7; 69.0±10.1 mmHg), and mean blood pressure (88.4±4.8; 91.3±7.8 mmHg) during water exercise compared to the land one. There were no significant differences in VO2 values between water and land exercises or between pregnant and non-pregnant women. After the first five-minute recovery period, both blood pressure and VO2 were similar to pre-exercise values. CONCLUSIONS: for pregnant women with 27 to 29 weeks of gestation, water exercise at the heart rate corresponding to VO2 is physiologically appropriate. These women also present a lower blood pressure response to exercise in water than on land.

Cardiopulmonary bypass alters the pharmacokinetics of propranolol in patients undergoing cardiac surgery

The pharmacokinetics of propranolol may be altered by hypothermic cardiopulmonary bypass (CPB), resulting in unpredictable postoperative hemodynamic responses to usual doses. The objective of the present study was to investigate the pharmacokinetics of propranolol in patients undergoing coronary artery bypass grafting (CABG) by CPB under moderate hypothermia. We evaluated 11 patients, 4 women and 7 men (mean age 57 ± 8 years, mean weight 75.4 ± 11.9 kg and mean body surface area 1.83 ± 0.19 m²), receiving propranolol before surgery (80-240 mg a day) and postoperatively (10 mg a day). Plasma propranolol levels were measured before and after CPB by high-performance liquid chromatography. Pharmacokinetic Solutions 2.0 software was used to estimate the pharmacokinetic parameters after administration of the drug pre- and postoperatively. There was an increase of biological half-life from 4.5 (95% CI = 3.9-6.9) to 10.6 h (95% CI = 8.2-14.7; P < 0.01) and an increase in volume of distribution from 4.9 (95% CI = 3.2-14.3) to 8.3 l/kg (95% CI = 6.5-32.1; P < 0.05), while total clearance remained unchanged 9.2 (95% CI = 7.7-24.6) vs 10.7 ml min-1 kg-1 (95% CI = 7.7-26.6; NS) after surgery. In conclusion, increases in drug distribution could be explained in part by hemodilution during CPB. On the other hand, the increase of biological half-life can be attributed to changes in hepatic metabolism induced by CPB under moderate hypothermia. These alterations in the pharmacokinetics of propranolol after CABG with hypothermic CPB might induce a greater myocardial depression in response to propranolol than would be expected with an equivalent dose during the postoperative period.