Mark Gaides

Marked weight reduction lowers resting and exercise blood pressure in morbidly obese subjects.

Obesity and high blood pressure (BP) often coexist. Weight reduction lowers resting BP but its effect on BP during exercise (a predictor of target organ damage) has not been evaluated. Blood pressure was measured at rest and during cycling, before and after weight reduction induced by gastric restriction. Nineteen subjects (4 male), 41 +/-2 (SEM) years of age and body mass index (BMI) of 43 +/- 0.9 kg/m2, were studied. On each occasion BP was measured at rest, at a steady state of 0 and 25 watts, at peak exercise and 1 min into recovery. Body weight was reduced by 28% +/- 6% and BMI decreased from 43.3 +/- 0.9 to 31.5 +/- 0.7 kg/m2 (P < .01). Both BP and heart rate, at rest and at all exercise intensities, were significantly lower after weight reduction. Resting BP decreased from 133 +/-4/87 +/- 3 mm Hg to 115 +/- 4/77 +/- 2 mm Hg (P < .001), and BP at peak exercise decreased from 181 +/- 8/98 +/- 4 to 162 +/- 6/83 +/- 5 mm Hg (P < .001). The change in resting systolic BP did not correlate with the change in body weight or with the change in heart rate, but it correlated with the baseline systolic BP (R = 0.61; P < .005). It is concluded that marked weight reduction reduces BP at rest and at all exercise intensities. Gastroplasty should be considered as an option in morbidly obese hypertensive patients who are not well controlled with conventional treatment, and who fail to lose or to maintain a reduced weight by calorie restriction alone.

Reduced exercise capacity in untreated adults with primary growth hormone resistance (Laron syndrome).

objective  Primary IGF‐I deficiency (Laron syndrome, LS) may decrease exercise capacity as a result of a lack of an IGF‐I effect on heart, peripheral muscle or lung structure and/or function.

Ventilatory Response to Hypercapnia in C5–8 Chronic Tetraplegia: The Effect of Posture

OBJECTIVE To study the effect of posture on the hypercapnic ventilatory responses (HCVR). DESIGN Nonrandomized controlled study. SETTING Rehabilitation hospital and a pulmonary institute. PARTICIPANTS Patients with neurologically stable C(5-8) tetraplegia (n=12) and healthy control subjects (n=7). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Supine and seated forced vital capacity (FVC) and HCVR, and supine and erect blood pressure. RESULTS FVC in the sitting position was reduced in patients with tetraplegia (52+/-13% predicted); supine FVC was 21% higher (P=.0005). In the sitting position, HCVR was lower in patients than in controls (0.8+/-0.4 vs 2.46+/-0.3 L/min/mmHg, P<.001). Supine HCVR was not significantly different between the groups. When HCVR was normalized to FVC, there was still a significant difference between patients and controls in the sitting position. Patients with tetraplegia were orthostatic (mean supine blood pressure 91+/-13 mmHg vs mean erect blood pressure 61+/-13 mmHg, respectively, P<.0001). The magnitude of the orthostatism correlated with that of the postural change in HCVR (r=.93, P<.0001). CONCLUSIONS Respiratory muscle weakness may contribute to the attenuated HCVR in tetraplegia. However, the observation that supine HCVR is still low even when normalized to FVC suggests a central posture-dependent effect on the HCVR, which may be linked to the postural effect on arterial blood pressure.

Effect of Thoracic sympathectomy on arm and leg exercise capacity and on lung function

Background: Thoracic T2–4 sympathectomy (TS) relieves palmar hyperhidrosis. These same roots innervate the heart and the lung. Thoracoscopic TS minimizes damage to the chest wall so that the effect of sympathectomy itself on these organs can be studied. We attempted to determine whether attenuated sympathetic output affects arm or leg exercise tolerance and lung function in young adults who underwent this operation. Methods: Seven subjects, aged 17–30 years, had lung function tests (water spirometer, Godart, Holland), and leg and arm maximal exercise (CPX, MedGraphics, USA), before and 3–6 months after TS. Results: After TS, resting and exercise heart rate and blood pressure were reduced. Baseline leg and arm peak O2 uptake, 2.08 (0.6) and 1.44 (0.5) liters/min, respectively, were not different from the post-TS values, 2.06 (0.7) and 1.54 (0.5) liters/min (nonsignificant). Post-TS lung functions were not significantly reduced. Conclusion: Thoracoscopic T2–4 sympathectomy does not lead to a clinically important fall in lung function and does not compromise arm or leg exercise capacity. Therefore, TS can be done safely in young subjects with palmar hyperhidrosis.

Aeration Properties of a New Sleeping Surface for Infants

Prone sleeping position, use of soft mattresses and head covering by bedclothes are known risk factors for sudden infant death syndrome (SIDS). Rebreathing carbon dioxide (CO2) may be a possible mechanism or a confounding factor of SIDS.

Central versus Peripheral Cardiovascular Limitation to Exercise: the Role of Two-Modality Testing

Background: Uncertainty arises when physiological findings indicate a cardiovascular limitation but the limiting constituents within the cardiovascular system cannot be identified. Objectives: It was the aim of this study to investigate the value of two-modality exercise testing to assess effort intolerance when the cause remains obscure despite standard exercise testing. Methods: A second modality maximal exercise test to fatigue, using either upper extremity or supine exercise, was performed following a nonconclusive standard sitting ergometry. Six patients (4 males) with a mean age of 56 ± 22 years with severe exercise intolerance were enrolled in the study. Results: In 4 of the patients, arm exercise capacity exceeded leg capacity, indicating peripheral limitation. In 1 of these patients, hemoglobin saturation decreased markedly only during sitting exercise while it remained normal during arm exercise, indicating a unique, iatrogenic abnormality. In another patient, supine leg exercise capacity exceeded sitting capacity, indicating peripheral venous limitation, and in an additional patient, leg capacity exceeded arm capacity pointing towards a central abnormality. In all 6 patients, the second modality test highlighted the correct diagnosis. Conclusions: Arm exercise that is added to a standard leg exercise may distinguish between central circulatory and peripheral vascular lower extremity limitation. Supine posture augments venous return to the heart and is useful when preload may be limiting. These modes of exercise may be added to a standard sitting or upright test in order to differentiate between central cardiovascular versus peripheral vascular (arterial or venous) causes of exercise limitation.

Lokomat walking results in increased metabolic markers in individuals with high spinal cord injury

Walking on the Lokomat, a motorized robotic gait orthosis (MRGO), was assessed as a method of increasing metabolic activity in individuals with high spinal cord injury. We assessed 11 participants, comparing sessions of robotic walking to passive pedaling, measuring oxygen consumption and carbon dioxide production. The robotic walking did increase the metabolic markers, while the passive pedaling did not.