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PubMed2005

Prognostic value of resting end-tidal carbon dioxide in patients with heart failure.

BACKGROUND: Cardiopulmonary exercise testing (CPET) variables provide valuable prognostic information in the heart failure (HF) population. The purpose of the present study is to assess the ability of resting end-tidal carbon dioxide partial pressure (PETCO2) to predict cardiac-related events in patients with HF. METHODS: 121 subjects diagnosed with compensated HF underwent CPET on an outpatient basis. Mean age and ejection fraction were 49.3 years (+/-14.7) and 28.4% (+/-13.4), respectively. Resting P(ET)CO2 was determined immediately prior to the exercise test in the seated position. Peak oxygen consumption (VO2) and the minute ventilation-carbon dioxide production (VE/VCO2) slope were also acquired during CPET. RESULTS: There were 41 cardiac-related hospitalizations and 9 cardiac-related deaths in the year following CPET. Mean resting P(ET)CO2, peak VO2 and VE/VCO2 slope were 34.1 mmHg (+/-4.6), 14.5 ml*kg(-1)*min(-1) (+/-5.1) and 35.9 (+/-8.7) respectively. Univariate Cox regression analysis revealed that resting P(ET)CO2 (Chi-square=28.4, p<0.001), peak VO2 (Chi-square=21.6, p<0.001) and VE/VCO2 slope (Chi-square=54.9, p<0.001) were all significant predictors of cardiac related events. Multivariate Cox regression analysis revealed resting P(ET)CO2 added to the prognostic value of VE/VCO2 slope in predicting cardiac related events (residual Chi-square=4.4, p=0.04). Peak VO2 did not add additional value and was removed (residual Chi-square=3.2, p=0.08). CONCLUSIONS: These results indicate a resting ventilatory expired gas variable possesses prognostic value independently and in combination with an established prognostic marker from the CPET. Resting P(ET)CO2 may therefore be a valuable objective measure to obtain during both non-exercise and exercise evaluations in patients with HF.

Adult↗
PubMed1989

Locomotor problems of supersonic aviation and astronautics.

Modern high-speed aviation and space flight are fraught with many problems and require a high standard of health and fitness. Those responsible for the health of pilots must appreciate the importance of early diagnosis even before symptoms appear. This is particularly true in terms of preventing spinal injuries where even a single Schmorl's node may make a pilot unfit for high-speed flying. Spinal fractures are frequent during emergency ejection and landing. Helicopter crews are particularly prone to spinal disc degeneration due to vibration. By effective lowering of vibration by changes in the seats, a reduction in such lesions is possible. The osteoporosis and muscle atrophy occurring among astronauts subjected to prolonged weightlessness can be prevented by regular physical exercises.

Aerospace Medicine↗
PubMed1994

Effects of acute beta-adrenergic receptor blockade on age-associated changes in cardiovascular performance during dynamic exercise.

The cardiovascular response to beta-adrenergic stimulation is markedly blunted with advancing age, and this blunting may underlie some of the prominent age-associated changes in the hemodynamic profile during dynamic exercise. To examine this hypothesis, we administered the nonselective beta-adrenergic receptor blocker propranolol (0.15 mg/kg IV) to 25 healthy normotensive men ages 28 to 72 years from the Baltimore Longitudinal Study of Aging (BLSA) immediately before maximal upright cycle ergometry with 99mTc gated cardiac blood pool scintigraphy. Their hemodynamic responses to exercise were compared with those of 70 age-matched healthy unmedicated male BLSA control subjects. The maximal cycle work rate achieved was similar in propranolol-treated men (158 +/- 32 W) and control subjects (148 +/- 32 W) and declined similarly with age in both groups. Hemodynamics at seated rest were not age-related in either group; however, propranolol-treated men had lower heart rates (HR), systolic blood pressure (SBP), ejection fraction, and cardiac index than control subjects but higher end-diastolic volume index (EDVI) and end-systolic volume index (ESVI) by covariance analysis. At maximal effort, several striking age-drug interactions were evident: Propranolol caused a greater reduction in HR and greater increases in EDVI and stroke volume index (SVI) in younger than in older men. Hence, at maximal work rate, HR declined less with age in the propranolol group (0.46 versus 1.09 beats per minute per year, P < .05 by covariance analysis); EDVI and SVI decreased with age (0.27 and 0.48 mL/m2 per year, respectively) after propranolol compared with increases of 0.47 and 0.16 mL/m2 per year in control subjects, respectively, each P < or = .05 by covariance analysis. The left ventricular contractility index, SBP/ESVI, at exhaustion was reduced by propranolol to a greater extent in younger than older men. Thus, acute beta-adrenergic blockade reverses the age-associated ventricular dilation at end diastole and end systole observed during upright cycle exercise and blunts the decline in maximal HR and myocardial contractility. These data suggest that the age-associated declines in maximal HR and left ventricular contractility during vigorous exercise are manifestations of reduced beta-adrenergic responsivity with advancing age which is partially offset by exercise-induced ventricular dilation.

Adrenergic beta-Antagonists↗
PubMed2005

Expiratory flow limitation is associated with orthopnea and reversed by vasodilators and diuretics in left heart failure.

BACKGROUND: In patients with acute left heart failure (LHF), orthopnea has also been related to the occurrence or worsening of expiratory flow limitation (EFL) in the supine position. We wished to assess whether short-term treatment with vasodilators and diuretics was able to abolish supine EFL and whether this could help to control orthopnea in patients with acute LHF. METHODS: In nine nonobese (ie, mean [+/- SD] body mass index, 24 +/- 5 kg/m2), never-smoker patients (two men and seven women; mean age, 77 +/- 7 years) with acute LHF (mean ejection fraction, 43 +/- 15%), we assessed EFL by the negative expiratory pressure method and dyspnea by the Borg scale, with patients in both the seated and supine positions, before and after short-term treatment with vasodilators and diuretics until hospital discharge. Orthopnea was defined as a positive difference in the Borg score between measurements made with the patient in the supine and seated positions. Postural variations in the end-expiratory lung volume were inferred from changes in inspiratory capacity (IC) that were measured under the same circumstances. RESULTS: Before treatment, with the patient in the seated position the mean dyspnea score was 1.5 +/- 0.5, the mean IC was 1.49 +/- 0.38 L, seven patients were non-flow-limited, and two patients were flow-limited. During recumbency, the mean dyspnea score was 2.7 +/- 0.5 (p < 0.01 vs seated position values), the mean IC was 1.66 +/- 0.45 L, and seven patients exhibited EFL. After a mean duration of 17 +/- 8 days of treatment (range, 7 to 28 days), EFL was detected in two patients only in the supine position, IC increased both in the seated position (1.65 +/- 0.34 L; p < 0.01) and the supine position (1.81 +/- 0.41 L; p = 0.07) position, and, although only two patients denied orthopnea, the mean dyspnea score during recumbency actually decreased to 1.9 +/- 1.0 (p < 0.05). CONCLUSIONS: Our results indicate that short-term treatment with vasodilators and diuretics is able to control orthopnea and to remove supine EFL in most patients with acute LHF, suggesting a posture-related increase in bronchial obstruction as the main mechanism of EFL, which appears to play a role in the occurrence and severity of orthopnea in these circumstances.

Aged↗
PubMed1976

[Possibilities of traffic-injury prevention using seat belts and their disadvantages].

As a result of the increasing number of serious injuries, and/or deaths caused by automobile accidents, seatbelts, along with other safety items are installed in cars. The idea of having automobile seatbelts came from the aircraft seatbelt. In our country there is no law requiring installation of seatbelts in all automobiles. Most imported cars, however do have built-in seat builts which are more or less used by the drivers and passengers. Wearing seatbelts is a necessity because, according to statistics, of 100,000 registered vehicles, 340.8 drivers and/or passengers lose their lives. In Sweden however, this value is 44.1 or eight times less. The number of injuries in Yugoslavia is also great. One of every three injuries are serious with chances of causing invalidity. The basic cause of death in an automobile accident is being thrown out of the vehicle by inertia during a collision has a five fold less a chance of surviving than if he were not thrown out. Secondary impacts of the passenger's body with objects within the automobile are: dashboard, doors, steering wheel, etc. are also a significant cause of many severe injuries. The force of inertia of a 70 kg passenger when the vehicle in which he is riding decelerates from a speed of 80 km/hr to 0 km/hr in a time span of 0.14 sec, and distances of 2 meters equals 878.83 kg. The greater the force of inertia is: (sometimes reaching 2000 kg). The advantages of the safety belt are in that they prevent ejection and secondary impacts of the passenger with protruding objects within the passenger compartment. Today the 2-point seatbelt is no longer in use, having been replaced by the 3-poing seat belt. The 3-point seatbelt must fit snugly about the wearers body so that it cannot be pulled away more than a distance of one or two fingerbreadths. The automatic 3-point seat belt, (the latest of designs), permits freedom of body movement. Should a collison occur, the seat belt locks in position holding the passenger back against the force of inertia. Disadvantages of the seat belt are illustrated by what is reffered to as the seat belt syndrome which was introduced by the American authors Garrett, and Baraunstein (1962). The presented 2,778 cases involved in automobile accidents, in which at least one passenger in each of the vehicles involved was wearing a seatbelt: 2,325 people). Of these 2,325, 944, 29%, or every third person was injured. 150 of them were injured on their lower torso. 26, or 0.8% were seriously injured. Not one case, however resulted in death. The seatbelt syndrome can be recognized by several characteristic injuries. In the event of a collision, those wearing seatbelts usually sustain multiple bruises and/or lacerations of the head, contusions of the lower abdomen with excoriation, adrasions, internal hemorraging, fractured ankle of foot. When such injuries are confirmed it is necessary to carefully search for injuries to internal organ as they usually accompany the above mentioned...

Abdominal Injuries↗
PubMed1988

Patterns of high-speed impact injuries in motor vehicle occupants.

Trauma from high-speed motor vehicle accidents is a leading cause of death and disability. Most of these injuries could be prevented if the driver and occupants of motor vehicles wore seatbelts or used other restraining devices. The injuries produced when an unrestrained occupant of a motor vehicle is ejected from that vehicle or impacts on a hostile surface at high speed occur in a reproducible pattern. The types of injuries sustained by drivers and front seat passengers are different and specific enough to allow one to identify drivers and passengers with confidence. Because of severe life-threatening injuries to the central nervous system, and thoracic and abdominal viscera, other serious injuries may be overlooked. Knowledge of the mechanism of injury and the role of the victim (i.e., driver or passenger) should lead to the prompt radiographic evaluation of all areas at risk. Our findings are based on a study of 250 drivers and 250 front seat passengers involved in motor vehicle accidents. We found distinct common injury patterns and radiographic findings in drivers and front seat passengers.

Abdominal Injuries↗
PubMed1985

Motor vehicle childhood injuries caused by noncrash falls and ejections.

In a sample of children aged 0 through 14 years who were treated for injuries incurred in a motor vehicle accident, a large proportion of those involved in noncrash events fell or were ejected from the vehicle. This study was designed to describe the patterns of passenger travel, precipitating causes, and severity of injury in noncrash falls or ejections. The data were obtained from a larger ongoing hospital-based monitoring system. The Abbreviated Injury Scale was used to grade injuries. Over 50% of those ejected sustained serious injuries compared with 5% of those who remained in the vehicle. Two high-risk patterns emerged: (1) the young child traveling in a passenger seat falling out of the vehicle, and (2) the older child riding on the exterior of the vehicle and falling off during a vehicle maneuver. Door locks, restraint use, and prohibition of travel in nonpassenger locations would prevent these serious noncrash injuries.

Accidents, Traffic↗
PubMedDate not supplied

Differences in cardiovascular profiles induced by mental arithmetic and by hand-eye task.

Five young, healthy male students performed two different psychophysical tests each lasting 1 min. The first test (A) consisted of mental arithmetic with digiting of results on a keyboard; the second test (G) consisted of playing an electronic game based on hand-eye coordination. Before and during each test, subjects remained seated with their thoraxes connected to an impedance cardiography monitor which gave, non invasively, beat-by-beat values of heart rate (HR), cardiac output (CO), stroke volume (SV) and left ventricle ejection time (VET). Systolic (SBP) and diastolic (DBP) arterial blood pressures were measured by means of a sphygmomanometer and total peripheral vascular resistance (TPR) and mean systolic ejection rate (MSER) were calculated. During test A, CO (A = +30%, G = +14%), HR (A = +26%, G = +2%) and SBP (A = +16%, G = +10%) increased more than during test G, while SV (A = +3%, G = +12%) and MSER (A = +11%, G = +14%) increased less and TPR (A = -13%, G = -7%) and VET (A = -7%, G = -2%) decreased more than in G. It was concluded that the analysis of a more complete cardiovascular profile may enhance distinctions among the behavioural stressors that induced different combinations in cognitive and sensory-motor responses.

Adult↗
PubMed1990

Interaction between left ventricular end-diastolic and end-systolic volumes in normal humans.

The extent to which the end-systolic volume (ESV) "follows" the end-diastolic volume (EDV) when the latter changes in response to various perturbations is a major determinant of the cardiac ejection fraction (EF) and has not been studied in humans. We measured EDV, ESV, and EF, determined by gated blood pool scans, during a change in posture from the supine to the upright seated position and during graded upright bicycle exercise. The experimental group consisted of 119 healthy individuals (79 males and 40 females) ranging in age from 21 to 81 yr and in physical-conditioning status (75-225 W maximum work load); rigorous screening excluded cardiac disease. Multiple regression analysis showed that the change in ESV (delta ESV) during a postural shift or during graded exercise was highly statistically correlated with the change in EDV (delta EDV) that occurred (r2 ranged from 0.34 to 0.49, correlation is positive) regardless of age, sex, or exercise work load. The correlation of delta ESV with delta EDV observed in this large sample, heterogeneous with respect to age, sex, and physical fitness, was also present in additional 31 subjects who exercised during beta-adrenergic blockade (propranolol 0.15 mg/kg). The delta EF with posture change and exercise in all subjects under all conditions was highly and inversely correlated with the delta ESV (r2 ranged from 0.38 to 0.81). Thus the delta ESV during the circulatory adaptive response to orthostatic and exercise stresses in humans is related to the delta EDV, and this relationship modulates the delta EF in response to these stresses.

Adult↗
PubMed1976

Ejection time--heart rate relationship during exercise.

The slope of the regression equation for left ventricular ejection time (LVET) vs heart rate (HR) is the appropriate factor for correcting LVET for HR. Because the regression relationship varies under different conditions, we determined the LVET-HR equations for subjects (1) seated at rest on a bicycle ergometer, and (2) during uninterrupted bicycle exercise. In 18 normally active male volunteers, ages 22-37, HR and LVET were measured under the two conditions and the regression relationship for LVET on HR determined for each. Regression equations are as follows: (1) LVET = 379-1.8 HR +/- 11.0 for subjects seated at rest on a bicycle ergometer, and (2) LVET = 371-1.2 HR +/- 13.9 for subjects performing upright bicycle exercise. The slope factors (1.8 and 1.2) differed significantly (p less than 0.01). The data indicate that considerable error can result from arbitrarily applying to exercising or resting subjects a correction factor which does not fit the conditions of the data to be corrected.

Adult↗
PubMed1980

Cardiovascular response to cooling of limbs determined by noninvasive methods.

Cold, even local exposure to a limited portion of the body, is a stress to man which elevates arterial pressure, thereby intensifying cardiac workload. The sequence of cardiac events following local cooling was noninvasively studied by observation of changes in cardiac interval, left ventricular ejection time, time from A wave of electrocardiogram to the peak of the dD/dt of the carotid pulse wave (which includes pre-ejection period), and amplitude of the pulse wave from a photoelectric cell on the earlobe, along with arterial pressures. Twelve subjects, aged 22--41 years, exposed a hand or foot to cold water for 1 min while seated and while supine (four experiements each). Results indicate that arterial pressure is monotonically elevated throughout the minute of exposure. Cardiac intervals are initially abbreviated, then return towards control. This may include an initial response to the cold, followed by a baroreflex at the heart. Subject posture and limb exposed also affect cardiac responses.

Adult↗
PubMed1999

Accidental decapitation: an unusual injury to a passenger in a vehicle.

A case of decapitation of a vehicle passenger in an accident on a highway is reported. Evaluation of roadside evidence and the deceased's injuries revealed that the victim was partially ejected from a broken passenger-side window as the vehicle spun out of control, decapitation being due to the impact of his head against a barrier stanchion on the shoulder of the road. An unfastened seat-belt, high-speed driving and the construction of the road barrier were contributory factors.

Accidents, Traffic↗
PubMed1975

Vertebral column injuries and seat belts.

It is obvious from the above that there are several independent mechanisms in the production of the various types of lumbar fractures. The details of these mechanisms must be fully understood in each case of lumbar vertebral injury. The cases reviewed in the present paper show that similar if not identical lumbar injuries can occur in car occupants wearing or not wearing lap belts at the time of the crash. Thus, cauxally relating a lumbar injury to the lap seat belt is in error. Only distraction injuries located between 1-2 and 1-4 with no evidence of either compression or anterior wedging can be causally related to a lap belt. Even some injuries with this typical confuguration have been observed in persons who were not belted (10). Thus, without knowledge of details of the crunch, lumbar fractures could mistakenly related to use of the lap belt. Thoraculumbar injuries have been senn in patients who were ejected from the car some time during the crash event. Relating the ejection event to the lumbar fracture must be done with great caution. As has been shown by Roaf (48) and by Kaufer and Hayes (33), the type and location of the lumbar spine injury can frequently and indicatory of load application. Other body injuries, or lack thereof, are often good clues to determine the point of load application causing lumbar injury. In addition, it has been recomended that additional details of the injury and of the accident be obtained for accuracy reporting of seat belt injuries.

Accidents, Traffic↗
PubMed1996

Absence of enhanced sympathoadrenal activity and behaviorally evoked cardiovascular reactivity among offspring of hypertensives.

To determine whether offspring of hypertensives show enhanced sympathetic nervous system activity, we evaluated several indices of sympathoadrenal activation and cardiovascular responsiveness to behavioral stimuli among 90 normotensive, young adult men having either one or two hypertensive parents (PH+(-), PH++) or normotensive parents only (PH--) (n = 30/group). Measurements included heart rate (HR) and blood pressure (BP) reactions to three mental stressors (the Stroop test, mental arithmetic, mirror tracing), a cold pressor test, postural adjustment (60 degrees upright tilt), isometric exercise and bicycle ergometry, as well as the 24-h excretion of catecholamines (epinephrine [E], norepinephrine [NE]) and venous plasma catecholamine concentrations, both at rest (seated and supine) and in response to the Stroop test and upright tilt. The three groups did not differ in age, education, body mass index (BMI), estimated aerobic fitness, resting HR, cardiac preejection period (PEP) and PEP:LVET (left ventricular ejection time) ratio, 24-h Na or K excretion, or fasting lipids, insulin or plasma renin activity. Resting systolic and diastolic BP varied as a function of parental hypertension, and were significantly higher in PH++ than among PH-- subjects (P < .05). No significant group difference was observed on any measure of plasma or urinary catecholamines, nor did offspring of hypertensives (PH++ or PH+-) showed greater HR or BP reactions than PH-- subjects to any of the several laboratory challenges. In sum, we find no evidence of enhanced sympathetic activity or heightened cardiovascular responsiveness among normotensive young adults who are familially predisposed to essential hypertension.

Adolescent↗
PubMed1989

Adequate preservation of right ventricular function after coronary sinus cardioplegia. A clinical study.

Whether retrograde coronary sinus cardioplegia adequately preserves right ventricular (RV) function is still a point of concern. Using technetium Tc 99m-labeled red blood cells, we assessed global and segmental RV function by first-pass and gated blood-pool radionuclide angiocardiography before and within 24 hours after aortic valve replacement in 14 consecutive patients (age, 58 +/- 5 years; mean +/- SEM). Coronary sinus cardioplegia was given in a multidose fashion at a flow rate of 50-70 ml/min through a balloon-tipped catheter, with the inflated balloon kept seated around the intra-atrial rim of the coronary sinus orifice. Additional myocardial protection was provided by systemic (25 degrees C) and topical hypothermia. Postoperatively, none of the patients had clinical or hemodynamic patterns suggestive of RV dysfunction. The postoperative global RV ejection fraction (0.49 +/- 0.03) was similar to the preoperative value (0.49 +/- 0.01). Analysis of segmental wall motion did not reveal postoperative abnormalities of new onset in any of the three anatomically defined RV regions (free wall, apex, and septum). Similarly, RV end-diastolic and end-systolic volume indexes (ml/m2) were not significantly affected by coronary sinus cardioplegia, being 71.6 +/- 5.8 and 36.1 +/- 3.5 before, and 67.4 +/- 3.8 and 34.5 +/- 2.3 after aortic valve replacement, respectively. We conclude that retrograde coronary sinus cardioplegia does not cause a detectable impairment of RV function if the balloon catheter does not obstruct the terminal tributaries of the coronary sinus and, hence, does not impede delivery of cardioplegia to right-sided cardiac structures.

Adult↗
PubMed1983

Correlations between ejection times measured from the carotid pulse contour and the impedance cardiogram.

Systolic time interval (STI) analysis is a commonly employed noninvasive technique for evaluating myocardial function. It requires simultaneous recording of an electrocardiogram, phonocardiogram, and the carotid pulse contour, from which left ventricular ejection time is measured. The carotid pulse contour may be difficult to record when there is subject movement, such as with exercise or other stresses utilized in aerospace medical research. Impedance cardiography is a relatively new noninvasive technique for measuring stroke volume. It also provides a measure of systolic ejection time without the necessity of recording a carotid pulse contour. The purpose of this study was to determine the correlation between left ventricular ejection time (LVET) determined from conventional STI analysis and systolic ejection time (T) obtained with impedance cardiography. The electrocardiogram, phonocardiogram, carotid pulse contour, and impedance cardiogram were monitored simultaneously in 17 male subjects 39-63 years of age (6 normotensive, 7 with established hypertension, and 4 with labile hypertension). Subjects were monitored at seated rest and during submaximal and maximal cycle ergometer exercise. Beat-by-beat analysis revealed high intrasubject correlations between LVET and T for each subject during all three activity levels. Correlations between LVET and T for the combined group of 17 subjects were: rest r = 0.990, submaximal exercise r = 0.976, maximal exercise r = 0.986; p less than 0.01. These results indicate impedance cardiography can be used in the determination of STIs for the evaluation of ventricular function, as well as for the noninvasive determination of stroke volume and cardiac output.

Adult↗
PubMed1983

Radiocardiographic evaluation of left ventricular function after inhalation of C15O2.

Inhalation of C15O2 delivers a bolus of labelled water into the pulmonary veins and the left atrium; analysis of the left ventricular curve provides an easy method for the evaluation of left ventricular function. the patient was seated before six collimated probes positioned toward the lungs. An additional probe was directed toward the heart in a modified 15 to 20 degrees left anterior oblique projection. One to two mCi C15O2 was administered per study. The left ventricular curve was analysed and the ejection fraction was calculated using a new method. The background was first calculated for the cycle with the largest diastolic counts using characteristic points of the curve before and after transit of the indicator through the left ventricle. For the other cycles, the background was considered to be a constant fraction of the end-diastolic counts. The left ventricular ejection fraction was obtained for each cycle after corresponding background subtraction as the ratio of diastolic activity minus systolic activity over diastolic activity. The ejection fraction thus determined in 20 patients was highly reproducible from beat to beat and from study to study in the same patient (r = 0.97 and 0.96). It corresponded closely to the ejection fraction determined using a camera-computer system (r = 0.92). We conclude that C15O2 inhalation is an easy, rapid, reproducible and attractive method to assess left ventricular function.

Adult↗