[Application and effects of blood flow restriction training]. / Anwendung und Effekte des "blood flow restriction training".

Blood flow restriction (BFR) limits arterial and venous blood flow and leads to blood pooling, which could increase exercise-induced training effects. Strength training at lower intensities (20-30% of maximum strength) in combination with BFR showed similar effects on muscle hypertrophy as training with 70% without BFR. Low-intensity cycling endurance training with BFR improves muscle hypertrophy and endurance performance and activates angiogenesis. After determination of the complete occlusion pressure on the corresponding extremity, it is recommended that BFR training should be performed with 40-80% of the measured occlusion pressure. During strength training of the upper extremities, an occlusion of 60-80% leads to a reduction in the arterial blood flow by 20-50%. Local ischemia and hypoxia, a stronger metabolic stimulus, swelling of the muscle cells and the increased oxidative stress are discussed as causes for the increased training effects due to BFR. In short-term studies, comparable adjustments to parameters of fibrinolytic activity, coagulation and inflammation could be observed for strength training with and without BFR. So far, thromboses after BFR have been described only rarely but need to be further clarified by appropriate studies. The BFR training leads to a stronger activation of the muscular metabolic reflex and thus to a relatively greater increase in exercise blood pressure, so that cardiovascular parameters should be controlled during BFR training. First meta-analyses with small numbers of healthy people and patients indicate the effectiveness of BFR training. Standardization or guidelines for clinical use are still lacking.

[Exercise and cellular adaptation of muscle]. / Körperliches Training und zelluläre Anpassung des Muskels.

Resistance training and to a lesser extent endurance training are capable of enhancing protein synthesis in skeletal muscle via various signaling pathways. Additionally, the expression of muscle fiber types responds to different regimes of training stimuli and immobilization as characterized by changes in myosin heavy chain isoforms (I<-->IIA<-->IIX). Eccentric resistance training has been shown to be highly efficient in inducing sarcomeric protein assembly in the longitudinal orientation of muscle cells. However, concentric contractions lead to a hypertrophic response (increased fiber diameter) in muscle which can still be activated in old age. The central signaling pathway to mediate the elevation of protein synthesis in response to training is the mTOR pathway, which is also stimulated by free amino acids. Moreover, adaptation to endurance training is mediated by the calcium-calcineurin-NFATc1 pathway which is strongly activated by the calcium transients involved in the muscle contraction process. High contraction frequency and long duration of training sessions are essential for activation and maintenance of fiber type I expression as well as for induction of transformation of type II into type I fibers. Endurance training sessions should therefore be longer than 30 min and dominated by periods of high frequency contractions. A further factor in the muscular response to training includes the recruitment and integration of satellite cells into muscle fibers. Satellite cells can respond to muscular stretch, activity and injury with increased proliferation and can later be integrated into muscle fibers. Therefore, new myonuclei are available to enhance mRNA synthesis and protein expression in muscle cells. New understanding of the cellular mechanisms of signal transduction in muscle in response to training, bed rest and ageing will help to optimize training and interventions in an ageing population.

Quantification of tension in Thera-Band and Cando tubing at different strains and starting lengths.

AIM: Elastic resistance exercise is frequently used in rehabilitation programs. Precise quantification using color coded bands is not possible. A method to predict forces for any length of mostly used elastic tubings and thereby a general equation for the comparison of elastic material is presented. METHODS: In an in vitro-series the tubing tension in relation to elongation of 6 colors of Thera-Band and Cando tubings was directly measured. The relation between tension and elongation was determined depending on different resting lengths. In clinical practice tension and elongation are prescribed. Two mathematical methods to calculate the resting length as regulatory variable are presented. One is based on the construction of iso-tension curves, the 2nd on the general mathematical relation delta % tension=K* % length change+n. RESULTS: 1. The tension/elongation relation is linear beyond a threshold in the early part of elongation. 2. The iso-tension method works graphically and facilitates the precise determination of resting length. 3. The double % relation between tension and elongation method describes the general properties of all tubings, where K=0.75 is a general constant. To calculate absolute values for the resting length, corresponding to a given tension and elongation, special ''color constants'' are presented. CONCLUSIONS: The prediction of maximum tension values for any given elongation is possible by simple variation of resting length. These findings may improve the usefulness of elastic tubings in rehabilitation programs. The mathematical method further may be used for the comparison of elastic materials with linear characteristics.

[MR-guided core biopsy of the shoulder: possibilities and experience with a vertically open 0.5T system]. / MRT-gesteuerte Stanzbiopsie der Schulter: Möglichkeiten und Erfahrungen an einem vertikal offenen 0.5-T-System.

PURPOSE: The availability of open whole body MRI magnets and MR-compatible instrumentarium were essential conditions for the progression of interventional MRI. The advantages of an MR-guided biopsy at the musculoskeletal system are the visualization of the puncture site of a representative area for tumor histology, the absence of exposure to radiation and the free selection of imaging planes. The purpose of the study was the development of a new technique of a secure MR-guided biopsy of intraosseus lesions in the humeral head. MATERIAL AND METHODS: MR-guided core biopsy of a intraosseus lesion of the humeral head was performed in five male patients on a vertical open, whole body MRI magnet (SIGNA SP/i 0.5T, GE Medical Systems). The technique using interactive MRI and the MR-compatible instrumentarium are described. RESULTS: A secure core biopsy could be obtained from a representative area for tumor histology in all cases. No complications occurred, especially no nerve or vessel lesion, no rotator cuff lesion and no intra-articular contamination of the shoulder joint were observed. CONCLUSION: A new technique is presented to obtain MR-guided core biopsies of intraosseous lesions of the humeral head. Furthermore, clinical indications of this technique are described.

[Quality of life and exercise capacity in lung transplant recipients]. / Lebensqualität und körperliche Leistungsfähigkeit bei Patienten nach Lungentransplantation.

BACKGROUND: Quality of life in lung transplant recipients (LTR) is reported to be comparable with that of the general population. However, previous studies have shown that exercise capacity was reduced to 30 - 40 % of normal values. The purpose of this study was to investigate the gap between good self-reported quality of life and reduced exercise capacity in LTR, to describe possible correlations and to compare the results with those of a control group (CG). METHODS: 27 LTR 208 +/- 67 days after bilateral lund transplantation (16 male, 11 female; age: 46 +/- 10 years; body mass index: 24 +/- 3 kg x m (- 2), FEV (1) % 75 +/- 27 %) and 30 controls (17 male 13 female; age 47 +/- 15 years; BMI: 26 +/- 4 kg x m (- 2), FEV (1) % 103 +/- 15 %) performed cardiopulmonary exercise testing and were interviewed with the standardized German "Quality of life profile for chronic disease" self-rating questionnaire. RESULTS: Significant differences were shown in objective exercise related variables (peak oxygen consumption: LTR 15.1 +/- 1.8, CG 34.5 +/- 9.1 ml x min (- 1) x kg (- 1); p < 0,01); peak workload: LTR 1.0 +/- 0.2; CG 2.4 +/- 1.0 W. kg (- 1); p < 0.01); percentage of predicted workload: LTR 44 +/- 12, CG 115 +/- 33 %; p < 0.01). The rating of subjective quality of life in physical, psychological and social domains of LTR did not differ from values of the CG or of the general population (n = 1143). The quality of life in the physical domain correlated significantly with peak exercise capacity (LTR r = 0.44, p < 0.05; CG r = 0.37; p < 0.05). CONCLUSION: Patients 7 months after lung transplantation described their physical, social and psychological quality of life as equally good as the healthy control group. However, peak exercise capacity and oxygen consumption were markedly reduced. To improve physical capacity in the range of daily activities, an exercise training program should be offered to patients after lung transplantation.

[Phase III rehabilitation after heart transplantation]. / Phase III Rehabilitation nach Herztransplantation. Effekte auf Lebensqualität, Leistungsfähigkeit und kardiovaskuläre Risikofaktoren.

INTRODUCTION: Longterm treatment after heart transplantation (HTX) improves survival, although the quality of life and exercise tolerance decreased continuously between one and ten years after transplantation. The role of physical exercise and psychological support in longterm treatment after HTX has not been determined. We analyzed the effects of a one year outpatient rehabilitation program in combination with a home based, computer assisted training program on exercise capacity, coronary risk factors and quality of life. METHODS: 20 heart transplant recipients in an intervention group and 12 patients after HTX in a control group participated in the study (IG (CG); 5.1+/-2.2 (4.5+/-2.3) years after HTX; age: 55+/-7 (54+/-8) years; body mass index: 28.3+/-1.0 (28.7+/-0.9) kg.m(-2)). Before and after the intervention, maximum and constant load exercise capacity, and self-reported quality of life were evaluated. The 12 month intervention period included 10 days of exercise testing as well as medical and psychological support. Furthermore, the IG group performed a computer-assisted and controlled home ergometer training every second day. RESULTS: After one year with 114+/-18 exercise training sessions, maximum oxygen consumption increased in the IG from 18.8+/-4.2 to 20.1+/-4.2 ml.min(-1).kg(-1) (p<0.05; CG 19.3+/- 4.5 to 18.5+/-2.8 ml.min(- 1).kg(-1); p<0.01 IG vs CG). In the IG, lower back pain, body fat, and blood pressure were all reduced, while the self-reported quality of life, endurance exercise capacity and HDL cholesterol were increased. No significant changes occurred in the control group. CONCLUSIONS: When initiated years after heart transplantation, longterm rehabilitation reduced coronary risk factors and significantly improved both the subjects' quality of life, as well as a near to normal capacity for physical work.

[Health-related quality of life after heart transplantation]. / Lebensqualität im Langzeitverlauf nach Herztransplantation.

BACKGROUND: Quality of life late after heart transplantation is reported to be comparable with that of the general population. However, peak exercise capacity remained approximately 60% of what was normal between 1 and 10 years after transplantation. The gap between patients' good quality of life and their impaired exercise tolerance is not yet explained. The purpose of our study was to examine the relation between quality of life and exercise- related variables in heart transplant recipients (HTR). Then, the results of these examinations were compared with those of patients having congestive heart failure (CHF), with the use of controls (C), respectively. METHODS: (Mean values+/-SD) 29 HTR 4.4 +/- 2.1 years after transplantation, 29 CHF (NYHA II n = 22, III n = 7) and 29 C (age 54 +/- 9, 61 +/- 10, 56 +/- 10 years, body mass index 28 +/- 3, 29 +/- 5, 28 +/- 4 kg x m(-2), body fat 25 +/- 4, 27 +/- 6, 26 +/- 5%, respectively) performed cardiopulmonary exercise testing and were interviewed with the standardized German "Quality of life profile for chronic diseases" questionnaire. RESULTS: Peak oxygen consumption was impaired in HTR and in CHF compared with C (19.0 +/- 4.5, 18.6 +/- 4.3, and 30.2 +/- 6.6 ml x min x kg(-1), respectively; p < 0.01 vs. C each). HTR and CHF patients' quality of life in the physical scores were both impaired (p < 0.05 or p < 0.01 vs. C, respectively), but HTRs have reported better scores than CHF (p < 0.05). In the psychological role, CHF was impaired against C (p < 0.05), and HTR scores were comparable with C. In social functioning HTR and CHF patients both showed reduced quality of life dimensions. The Pearson correlation analysis showed that quality of life in physical functioning was related to peak oxygen consumption (p < 0.001) and percentage of predicted workload (p < 0.001). Quality of life in the social and psychological domains showed no association to exercise-related values. CONCLUSIONS: In HTR and in CHF, exercise testing variables were dominant predictors among the physical scales in quality of life, but not among social or psychological scales. Therefore, even late after heart transplantation, improving physical capacity should be a therapeutic goal with the intention of further increasing the quality of life.

[Exercise recommendation and catecholamines in patients with coronary artery disease]. / Belastungsdiagnostische Kenngrössen und Katecholamine bei Koronarpatienten.

Exercise training for patients with coronary artery disease (CAD) is recommended in a wide range between 40-85% of maximum functional capacity (MFC) or 55-90% of maximum heart rate (HR). During exercise, high levels of catecholamines and metabolic acidosis could induce arrhythmia and ischemia. But catecholamines have never been determined in CAD during constant load exercise in the upper range of recommended intensities. In 11 CAD patients (age 58+/-8 years, BMI 26.1+/-4.0 kg x m(-2), NYHA I n=7, II n=4) we tested the maximum functional capacity (MFC), norepinephrine (NE), epinephrine (E) and blood lactate ([Lac(-)](B)) in a symptom-limited incremental ergometer test. Related to the exercise recommendation, the kinetics of NE, E and [Lac(-)](B) were determined in two 30 min constant load tests in randomized order: one was performed at the anaerobic lactate threshold (CTAT), a second was performed 10% above the individual threshold intensity (CT+10%). In the incremental tests maximum workload and VO(2) were 141+/-54 W and 1766+/-532 ml x min(-1), respectively (85+/-22% of normal; [Lac(-)](B) 5.7+/-1.9 mmol x l(-1), HR 138+/-28 b x min(-1), NE 11.7+/-5.1, E 1.6+/-1.4 nmol x l(-1)). In CTAT the anaerobic threshold (63+/-7% of MFC) represented the mean range of recommended exercise intensity for CAD (40-85%) and could be validated as steady-state intensity because catecholamines and [Lac(-)](B) concentrations remained constant after the initial increase (workload 88+/-35 W, [Lac(-)](B) 3.3+/-1.4 mmol x l(-1), HR 117+/- 23 b x min(-1), NE 8.3+/-3.5, E 0.8+/- 0.7 nmol x l(-1)). In all patients CT+10% (71+/-7% of MFC) led to a continuous rise in [Lac(-)](B), to a NE overload and to earlier exhaustion, although the intensities were in the recommended training range (workload 100+/-38 W, [Lac(-)](B) 5.8+/- 1.9 mmol x l(-1), HR 129+/- 29 b x min(-1), NE 13.9+/-6.9, E 1.5+/- 1.7 nmol x l(-1); p<0.01 against CTAT for all except E). Conclusions In the upper range of recommended training intensity for CAD patients, norepinephrine and lactate were higher during endurance exercise than at MFC in incremental tests. Endurance exercise with intensities >70% of MFC could overload the cardiac patient and increase the risk of arryhthmia and ischemia. Therefore, endurance exercise should be performed below 70% of MFC or below 85% of maximum HR, respectively, whereas higher intensities should apply to interval exercise.

[Determining the extent of intensive physical performance in patients with coronary heart disease]. / Bestimmung des Bereichs intensiver Dauerleistungsfähigkeit bei Patienten mit koronarer Herzkrankheit.

Intensive physical exercise improves cardiac perfusion, skeletal muscle function and risk factors in patients with coronary artery disease (CAD). Otherwise, overdosed intensity can induce training adaptation as well as cardiac events. Therefore, we tested whether exercise intensity corresponding to an equilibrium between lactate production and elimination from the blood during incremental exercise tests represented the blood lactate [Lac-]B steady-state intensity during constant physical training. Randomized into two groups with 30 CAD patients each (T1: 25 male, 5 female; 59 +/- 7 years; T2: 26 male, 4 female; 60 +/- 9 years), the patients initially performed two successive incremental exercise tests. In the first test, workload was increased stepwise until exhaustion or symptom limitation (maximal workload: T1 142 +/- 48 watts, T2 145 +/- 45 watts) with the corresponding [Lac-]B accumulation of up to 6.7 +/- 2.6 (T1) or 6.5 +/- 2.0 (T2) mmol/l, respectively. After a seven minute active rest the second test began with 25 watts, increased with 5 (maximum workload in first test < 100 watts) or 10 watts per minute, respectively. During lower intensities in the second test, [Lac-]B initially decreased to an individual lactate minimum intensity (workload at LMI 83 +/- 32 in T1 or 86 +/- 29 in T2 watts, respectively; [Lac-]B at LMI 4.6 +/- 2.2 and 4.9 +/- 1.8 mmol/l, respectively) and then increased again. To check if the individual LMI represented the [Lac-]B steady-state workload in constant workload exercise, the patients performed 30 min constant load tests with the LMI (CT1) or a 30 min constant load test with an intensity 10% above the LMI (CT2), respectively. The workload in CT1 was 83 +/- 32 watts with a mean exercise time of 29.0 +/- 1.7 min. After 10 min of exercise the [Lac-]B steady state was reached at 3.3 +/- 1.4 mmol/l with no further increase in the last 20 min. The mean workload in CT2 was 95 +/- 31 watts with an exercise time of 23.3 +/- 8.3 min (p < 0.01). [Lac-]B increased from 4.4 +/- 1.7 mmol/l after 10 min to 4.7 +/- 2.0 mmol/l at the end (p < 0.01). Fifty percent of patients stopped CT2 before the 30 minute end. The results indicates that the LMI, estimated during lactic acidosis in two successive incremental tests, represented the individual lactate steady-state intensity also during constant load exercise. Therefore, training regimens for CAD patients could be deduced from LMI.

[Rope pulley isokinetic system in shoulder rehabilitation--initial results]. / Seilzugisokinetik in der Schulterrehabilitation--erste Ergebnisse.

AIM: Of this study was to evaluate the results of a shoulder rehabilitation program of different shoulder diseases, based on an isokinetie pulley system ("Moflex", Recotec/Bernina, Swiss). METHOD: In this prospective study 70 patients participated in a standardized rehabilitation program (instability: n = 19; rotator cuff disorders: n = 23; impingement syndrome without lesion: n = 16; others: n = 12; operative therapy: n = 47). The major aspect of the program was an isokinetic pulley system. RESULTS: Isokinetic training with the used device affords strict monitor-feedback to avoid critical torque values. Strength which was attained without relevant pain was almost linearly increased by a mean of 31% until the 20th day of rehabilitation, workload by 79%. At the end of the rehabilitation program the strength of the affected (mostly dominant) shoulder was 15% higher than in the unaffected shoulder; the respective workload values were almost equal. CONCLUSION: These first results demonstrate the value of the isokinetic pulley system in the rehabilitation of the investigated shoulder diseases. The equipment may be used already in an early postoperative state. First results of strength increases using an isokinetic pulley system in shoulder rehabilitation are presented.

[Ambulatory long-term rehabilitation of heart patients]. / Ambulante Langzeitrehabilitation von Herzpatienten.

In Germany cardiac rehabilitation contains a comprehensive 3 to 4 week inpatient program. The aim of our study was to perform an outpatient long-term rehabilitation including intense exercise and behavior therapy. In this setting the health benefits could be increased over the first 6 months. Hundred and twelve patients (94 men and 18 women, age 55 +/- 11 years) after myocardial infarction (52%), bypass-surgery (37%), PTCA (23%), and others (15%) were included in the ongoing study. Cholesterol and LDL-cholesterol diminished significantly. HDL-cholesterol was increased significantly after 6 months. The endurance exercise capacity per rate-pressure-product was increased by 46% during the 6 months period. The intake of cholesterol could significantly be diminished from 307 +/- 25 to 258 +/- 19 mg per day. Five of 16 patients became free from smoking. The first results from the long-term outpatient program show that the time of intervention and also the intensity of the medical, exercise and the behavior therapy are important factors for a successful rehabilitation.

Estimation of an individual equilibrium between lactate production and catabolism during exercise.

During an incremental exercise test after a preceding bout of maximum exercise, blood lactate initially decreases to an individual minimum and then increases again. To determine whether this minimum represents an individual equilibrium between lactate production and catabolism during constant load exercise, the following field tests were performed: in 25 runners and five basketball players (series 1) the speed corresponding to the individual lactate minimum (LM) was measured in test 1 (incremental test after exercise induced lactic acidosis). On two occasions, two constant speed runs over 8 km were performed, one using the LM speed (LMS) (test 2), and another at a running speed of 0.2 m.s-1 above the LMS (test 3). Results of runners/basketball players: blood lactate concentration ([Lac-]B) in test 2 changed from 3.6/4.9 mmol.l-1 to 4.0/4.9 mmol.l-1 during the last 4.8 km, in test 3 from 4.6/4.6 mmol.l-1 to 6.5/6.9 mmol.l-1. These results indicate: 1) the LM speed in test 1 corresponds to a maximum lactate steady state speed during constant load exercise; 2) only a slight speed increase above the LM speed results in continuous marked [Lac-]B increase and earlier exhaustion. Variation of the increment duration in 13 males (series 2) shows no change of the LMS using 800-m and 1200-m increments (4.49 and 4.44 m.s-1) but a marked shift to higher speed using 400-m increments (4.96 m.s-1). Effects of low muscle glycogen stores on the LMS were determined in 10 males (series 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of oxylabile CO2 in human blood by lactate.

The influence of lactic acid, hydrochloric acid, and sodium lactate addition (10 mmol/l each) on oxylabile CO2 was investigated in blood of male subjects after equilibration at 37 degrees C with 3, 6, and 10% CO2 in N2 and O2, respectively. The total CO2, pH in whole blood and erythrocytes, oxygen saturation, hemoglobin concentration, and hematocrit value were measured. With these data we calculated bicarbonate and carbamate concentrations and the corresponding differences between oxygenated and deoxygenated blood. The amount of oxylabile bicarbonate was not systematically influenced by the various experimental conditions. The carbamate content, however, was larger in deoxygenated than in oxygenated blood (up to 0.08 mol/mol hemoglobin) only in the absence of lactate. In the presence of lactic acid as well as sodium lactate, the carbamate content in oxygenated blood was higher by 0.06-0.13 mol/mol hemoglobin than in deoxygenated blood. The lactate effect even increased after 2,3-diphosphoglycerate depletion. We suggest, therefore, a competition between CO2 and the lactate ion at the NH2-terminal valine of the beta-globin chain in deoxygenated hemoglobin.

Determination of plasma volume and total blood volume using indocyanine green: a short review.

Rapid blood and plasma volume measurements gain increasing interest in order to avoid unnecessary blood transfusions. Only the indocyanine green method seems to satisfy the demand for a fast, safe and reproducible bedside method. We summarized older and newer experiences with this method, and also summarized the results for practical application.

Plasma volume estimation using indocyanine green. A single intravenous injection method.

The validity and reliability of plasma volume estimation using indocyanine green were investigated in five in vitro experiments and in three in vivo series. The in vitro measurements reflected real volumes with an error of about 1%. Comparative measurements in the same patients using indocyanine green or Cr51 labelled red cells differed by 1.7% (r = 0.97). The mean (SD) plasma volume difference between two successive plasma volume measurements using indocyanine green was 38 (43) ml (r = 0.99). Plasma volume measured before and about 7 min after a hyperosmolar saline bolus (100 ml, 1 molar) was increased by 223 (102) ml and 286 (49) ml when determined by indocyanine green and plasma protein changes respectively. Nevertheless, the necessity for central venous injection and arterial sampling restricts the possible application of the method to intra-operative or emergency care use.

Plasma potassium and ventilation during incremental exercise in humans: modulation by sodium bicarbonate and substrate availability.

It has recently been demonstrated that, compared to normal conditions, ventilation (VE) was increased during exercise after glycogen depletion, in spite of a marked increase in plasma pH (pHP). It was further demonstrated that VE in patients with McArdle's syndrome was reduced when substrate availability was improved. In the present experiments, six endurance trained men performed two successive cyclo-ergometric incremental exercise tests (tests A, B) after normal nutrition (N) and after a fatty meal in conjunction with a sodium bicarbonate (NaHCO3) solution (FSB) or without NaHCO3 (F), and the relationship between VE, plasma potassium concentration ([K+]P), and pHP was checked. Plasma free fatty acid concentration ([FFA]P) was markedly increased in the F and FSB trials (P < 0.001). In FSB pHP was significantly increased, compared to N and F (P < 0.001). In all the B tests, pHP increased during moderate and intense exercise and in FSB, remained alkalotic even during maximal exercise intensity. In contrast, VE and [K+]P changes were almost equal in all the trials and in tests A and B. It was found that exercise-induced changes of VE and [K+]P in the present experiments were not markedly affected by [FFA]P or pHP values and that these changes also occurred independently of changes in pHP or plasma bicarbonate concentration. The often used glycogen depletion strategy may have slightly increased VE but apparently did not overcompensate for a possible decrease in VE due to increased pHP.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between plasma potassium and ventilation during successive periods of exercise in men.

During and after two successive incremental cycle ergometer tests (tests A and B), plasma potassium concentration ([K+]p), plasma pH (pHp), plasma partial pressure of carbon dioxide, blood lactate concentration ([Lac-]b) and ventilation (VE) were measured. While there was a good correlation between the increase in [K+]p and VE or pHp, respectively, in test A, in test B a close correlation was found only between the increase in VE and [K+]p (r greater than 0.9 for nearly all single cases; r was 0.84 and 0.89 for all (pooled) cases in tests A and B, respectively; the correlation coefficients between changes in pHp and VE in tests A and B were r = 0.74 and r = 0.28, respectively, and r = 0.89 and r = 0.10 between the changes in [Lac-]b and VE in tests A and B). The close relationship for individuals between VE and [K+]p in tests A and B supported the hypothesis that the extracellular increase in [K+] may contribute to the ventilatory drive during exercise. The comparison of the results of tests A and B further indicated that the relationship between pHp and VE was dependent on the experimental design, and that pHp and VE changes are unlikely to be cause and effect.

Short term volume effects of a hypertonic saline bolus during neurosurgery.

Intracranial hypertension which does not respond to customary hyperosmotic agents may successfully be treated with hypertonic saline. The absence of diuresis and the maintainance of intravascular volume are supposed to be the main advantages of hypertonic sodium chloride. Volume overload and toxic hyperosmolality from frequent application of such solutions are possible disadvantages. The presented experiments checked the time course of intravascular volume shifts after a 100 ml 1-molar saline bolus in 14 patients during neurosurgery using plasma protein concentration changes. An initial intravascular volume expansion of about 270 ml remained quite unchanged for the first 8 minutes, followed by a nearly linear decrease. Extrapolation of the curves demonstrated that the preinfusion state would have been reached after about 20 minutes. Osmolality remained increased by about 4 mosmol/kg 15 min after the bolus. Thus it appears that repetitive infusion of these amounts of hypertonic saline will cause no serious volume overload if 30 minutes intervals are kept, but osmolality should be checked before each bolus.

Relation between plasma K+ and ventilation during incremental exercise after glycogen depletion and repletion in man.

1. We have examined the relationship between expiratory ventilation (VE), plasma potassium concentration ([K+]P), blood lactate concentration ([Lac-]B), and plasma pH (pHP) in five trained men before and after glycogen depletion and repletion in two successive incremental bicycle ergometer tests (tests A and B). 2. Though pHP was significantly higher after glycogen depletion (in relation to normal or repleted conditions) VE and [K+]P also tended to be higher. 3. There was no constant relation between the magnitude or the direction of change in lactic acidosis, or VE and [K+]P, respectively. Instead, a close temporal relationship between changes in VE and [K+]P was found. 4. A non-linear increase in VE occurred independently of changes in pHP or [Lac-]B, but could be well predicted from a non-linear increase in [K+]P. 5. These findings indicate that lactic acidosis had no deciding effect on exercise ventilation in these experiments. They are consistent with the idea that the potassium increase may contribute to the ventilatory drive during exercise.