Mariana Dias’s research while affiliated with Pontifical Catholic University of Rio Grande do Sul and other places

Cardiopulmonary resuscitation (CPR) is a series of resuscitation actions that improve the survival chances after a cardiac arrest, maintaining tissue perfusion through sternal compressions. The aim of this study was to clarify potential differences in upper body muscle activity related to CPR in microgravity and hypogravity (Mars gravitational field). Thirty healthy male volunteers each performed 3 sessions of 30 external chest compressions (ECCs) on a mannequin, during which time the muscle activity of the pectoralis major, triceps brachii and rectus abdominis were recorded via superficial electromyography. Hypogravity and microgravity were simulated by means of a body suspension device and a counterweight system, to which the volunteer was connected via a harness. The standard terrestrial (1G) CPR position was adopted in simulated hypogravity, and the Evetts–Russomano method was used in simulated microgravity. Heart rate and perceived exertion were also measured via Borg scale. No significant difference was found between the ECCs per minute and per set of compressions when performed at 1G and in simulated hypogravity. However, the mean depth achieved during compressions showed a significant difference in hipogravity. After 3 sets of 30 ECCs, mean heart rate showed an increase from rest values to those obtained from the 3 gravitational fields, and also from 1G to microgravity, but not from 1G to hypogravity. Mean of perceived exertion presented a significant increase from 1G to hypograviy and to microgravity. Muscle activation during the performance of CPR at 1G and hypogravity was significantly higher for the rectus abdominis. All muscles were more active during CPR in microgravity when compared with 1G. These findings suggest that the rescuer should be physically well trained in order to deliver adequate CPR in extraterrestrial environments. The physical training should aim to improve muscular endurance and cardiorespiratory capacity to increase effectiveness of the rescuer emergency assistance.

Introduction: Cardiopulmonary resuscitation (CPR) in microgravity is challenging. There are three single-person CPR techniques that can be performed in microgravity: the Evetts-Russomano (ER), Handstand (HS), and Reverse Bear Hug (RBH). All three methods have been evaluated in parabolic flights, but only the ER method has been shown to be effective in prolonged microgravity simulation. All three methods of CPR have yet to be evaluated using the current 2010 guidelines. Methods: There were 23 male subjects who were recruited to perform simulated terrestrial CPR (+1 G(z)) and the three microgravity CPR methods for four sets of external chest compressions (ECC). To simulate microgravity, the subjects used a body suspension device (BSD) and trolley system. True depth (D(T)), ECC rate, and oxygen consumption (Vo2) were measured. Results: The mean (+/- SD) D(T) for the ER (37.4 +/- 1.5 mm) and RBH methods (23.9 +/- 1.4 mm) were significantly lower than +1 G(z) CPR. However, both methods attained an ECC rate that met the guidelines (105.6 +/- 0.8; 101.3 +/- 1.5 compressions/min). The HS method achieved a superior D(T) (49.3 +/- 1.2 mm), but a poor ECC rate (91.9 +/- 2.2 compressions/min). Vo2 for ER and HS was higher than +1 Gz; however, the RBH was not. Conclusion: All three methods have merit in performing ECC in simulated microgravity; the ER and RBH have adequate ECC rates, and the HS method has adequate D(T). However, all methods failed to meet all criteria for the 2010 guidelines. Further research to evaluate the most effective method of CPR in microgravity is needed.

Introduction: Studies were conducted to evaluate cardiopulmonary resuscitation (CPR) in a simulated low gravitational field, such as Mars (hypoG), aimed at providing an insight into the performance of terrestrial CPR. Methods: Two studies were conducted to evaluate external chest compressions (ECC) depth and rate, as well as perceived exertion (RPE) and the physiological cost, when 4 sets of 30 ECCs were performed on a standard CPR mannequin for 1.5 min during Mars simulation, using terrestrial (1 Gz) as control. The first study (n = 20; 2005 guidelines) also evaluated the electromyographic (EMG) activity of four muscles (triceps brachii, erector spinae, upper rectus abdominis, pectoralis major). The second study (n = 30; 2010 guidelines) included range of elbow flexion, minute ventilation (VE) and peak oxygen consumption (VO2 peak) measurements. HypoG simulation was achieved using a body suspension device (BSD) and a counterweight system. Results: In both studies, subjects successfully performed ECCs at 1Gz and hypoG. In the first study, there were increases from 1Gz values of 32% (p < 0.001) for RPE and 44% (p = 0.002) for HR when ECCs were performed during Mars simulation. In hypoG, the triceps brachii showed less activity when compared with the other three muscles studied (p < 0.001). A higher RPE (p < 0.05) was also seen in the second study, which was accompanied by an increased VE (11.4±5.9 to 37.5±10.3 L min−1, p < 0.05) and VO2 peak (3.2±1.1 to 20.5±7.6 mLkg−1 min−1, p < 0.05). The arm flexion angle during hypogravity CPR, compared to 1 Gz CPR, was also increased (4.3±2.8◦ to 14.0±8.1◦, p < 0.05). Conclusion: Simulated reduction of upper body weight did not decrease the ability to perform proper ECCs, however, it increased the physiological cost and altered performance of the ‘straight arm’ CPR technique. These findings could be used to improve terrestrial CPR, especially when physical disparities are encountered with the rescuer being smaller and lighter than the patient.

The purpose of this study was to evaluate the effects of a resistance exercise training versus an endurance training on the morpho-functional aspects of elderly men. The sample was made of 31 elderly men, divided into two groups, where 17 subjects (66.35±3.82 yrs) performed resistance exercise training (RET) and 14 subjects (69.21±6.90 yrs) performed endurance training (ET), for 12 weeks. The variables assessed were muscle thickness, body composition, electromyographic muscle activity (EMG), force production and functional mobility. A two-way ANOVA (by group and by intervention) for repeated measurements (pre-and post-) was used for the comparison of EMG. The remaining variables were analyzed intra-group (pre-and post-) using paired Student's t-test. The significance level adopted was of 5%. The ET showed significantly higher reduction in total body mass and body mass index (BMI) in comparison to the RET group. The RET group showed significantly greater gains in force production and muscle thickness when compared to the ET. Our results suggest that the combination of RET using Swiss balls and rubber bands, in other words, low cost materials, in addition to easy adherence ET, as walking, can improve the neuromuscular system and body composition.

Current 2010 terrestrial (1Gz) CPR guidelines have been advocated by space agencies for hypogravity and microgravity environments, but may not be feasible. The aims of this study were to (1) evaluate rescuer performance over 1.5 min of external chest compressions (ECCs) during simulated Martian hypogravity (0.38Gz) and microgravity (μG) in relation to 1Gz and rest baseline and (2) compare the physiological costs of conducting ECCs in accordance with the 2010 and 2005 CPR guidelines. Thirty healthy male volunteers, ranging from 17 to 30 years, performed four sets of 30 ECCs for 1.5 min using the 2010 and 2005 ECC guidelines during 1Gz, 0.38Gz and μG simulations (Evetts-Russomano (ER) method), achieved by the use of a body suspension device. ECC depth and rate, range of elbow flexion, post-ECC heart rate (HR), minute ventilation (VE), peak oxygen consumption (VO2peak) and rate of perceived exertion (RPE) were measured. All volunteers completed the study. Mean ECC rate was achieved for all gravitational conditions, but true depth during simulated microgravity was not sufficient for the 2005 (28.5 ± 7.0 mm) and 2010 (32.9 ± 8.7 mm) guidelines, even with a mean range of elbow flexion of 15°. HR, VE and VO2peak increased to an average of 136 ± 22 bpm, 37.5 ± 10.3 L·min-1, 20.5 ± 7.6 mL·kg-1·min-1 for 0.38Gz and 161 ± 19 bpm, 58.1 ± 15.0 L·min-1, 24.1 ± 5.6 mL·kg-1·min-1 for μG from a baseline of 84 ± 15 bpm, 11.4 ± 5.9 L·min-1, 3.2 ± 1.1 mL·kg-1·min-1, respectively. RPE was the only variable to increase with the 2010 guidelines. No additional physiological cost using the 2010 basic life support (BLS) guidelines was needed for healthy males performing ECCs for 1.5 min, independent of gravitational environment. This cost, however, increased for each condition tested when the two guidelines were compared. Effective ECCs were not achievable for both guidelines in simulated μG using the ER BLS method. This suggests that future implementation of an ER BLS in a simulated μG instruction programme as well as upper arm strength training is required to perform effective BLS in space.