Impact of daily artificial gravity on autonomic cardiovascular control following 60-day head-down tilt bed rest.

Impaired cardiovascular autonomic control following space flight or immobilization may limit the ability to cope with additional hemodynamic stimuli. Head-down tilt bedrest is an established terrestrial analog for space flight and offers the opportunity to test potential countermeasures for autonomic cardiovascular deconditioning. Previous studies revealed a possible benefit of daily artificial gravity on cardiovascular autonomic control following head-down tilt bedrest, but there is a need for efficiency in a long-term study before an artificial gravity facility would be brought to space. We hypothesized that artificial gravity through short-arm centrifugation attenuates functional adaptions of autonomic function during head-down tilt bed rest. 24 healthy persons (8 women, 33.4 ± 9.3 years, 24.3 ± 2.1 kg/m2) participated in the 60-day head-down tilt bed rest (AGBRESA) study. They were assigned to three groups, 30 min/day continuous, or 6(5 min intermittent short-arm centrifugation, or a control group. We assessed autonomic cardiovascular control in the supine position and in 5 minutes 80° head-up tilt position before and immediately after bed rest. We computed heart rate variability (HRV) in the time (rmssd) and frequency domain, blood pressure variability, and baroreflex sensitivity (BRS). RR interval corrected rmssd was reduced supine (p = 0.0358) and during HUT (p = 0.0161). Heart rate variability in the high-frequency band (hf-RRI; p = 0.0004) and BRS (p < 0.0001) decreased, whereas blood pressure variability in the low-frequency band (lf-SBP, p = 0.0008) increased following bedrest in all groups. We did not detect significant interactions between bedrest and interventions. We conclude that up to daily 30 min of artificial gravity on a short-arm centrifuge with 1Gz at the center of mass do not suffice to prevent changes in autonomic cardiovascular control following 60-day of 6° head-down tilt bed rest. Clinical Trial Registration: https://drks.de/search/en/trial/DRKS00015677, identifier, DRKS00015677.

Effects of daily artificial gravity training on orthostatic tolerance following 60-day strict head-down tilt bedrest.

PURPOSE: Orthostatic intolerance commonly occurs following immobilization or space flight. We hypothesized that daily artificial gravity training through short-arm centrifugation could help to maintain orthostatic tolerance following head-down tilt bedrest, which is an established terrestrial model for weightlessness. METHODS: We studied 24 healthy persons (eight women; age 33.3 ± 9.0 years; BMI 24.3 ± 2.1 kg/m2) who participated in the 60-days head-down tilt bedrest (AGBRESA) study. They were assigned to 30 min/day continuous or 6 × 5 min intermittent short-arm centrifugation with 1Gz at the center of mass or a control group. We performed head-up tilt testing with incremental lower-body negative pressure until presyncope before and after bedrest. We recorded an electrocardiogram, beat-to-beat finger blood pressure, and brachial blood pressure and obtained blood samples from an antecubital venous catheter. Orthostatic tolerance was defined as time to presyncope. We related changes in orthostatic tolerance to changes in plasma volume determined by carbon dioxide rebreathing. RESULTS: Compared with baseline measurements, supine and upright heart rate increased in all three groups following head-down tilt bedrest. Compared with baseline measurements, time to presyncope decreased by 323 ± 235 s with continuous centrifugation, by 296 ± 508 s with intermittent centrifugation, and by 801 ± 354 s in the control group (p = 0.0249 between interventions). The change in orthostatic tolerance was not correlated with changes in plasma volume. CONCLUSIONS: Daily artificial gravity training on a short-arm centrifuge attenuated the reduction in orthostatic tolerance after 60 days of head-down tilt bedrest.

Development of a lower body negative pressure box with an environmental control system for physiological studies.

A headward fluid shift occurs during microgravity exposure, which causes the cardiovascular adaptive syndrome. Different countermeasures have been proposed to decrease its symptomatology, like the application of lower body negative pressure (LBNP). A LBNP box with an environment control system was developed, aiming to improve features of LBNP boxes used worldwide. It consists of five carbon steel ribs in the shape of a cylinder, which is wrapped with high pressure resistant and transparent vinyl. Inner and outer-wheeled trolleys can comfortably and easily move the subject in and out of the box. A custom-made skirt is secured around the subject's waist by an adjustable belt. The other end is secured between two window-type wooden structures, which seal the LBNP box. Inlet and an outlet valves connect the external to the internal environment of the chamber and tube system allows air to circulate gently. Electronic sensors are used to adjust the airflow keeping a pre-set negative pressure without changing humidity and temperature inside the box. Structural, pressure profile and leaking tests were performed with successful results. The improvements of the present LBNP box have substantially decreased the undesirable side effects of uncontrolled environment conditions during rapid pressure changes, and increased test subjects' comfort.

Left ventricular regional wall motion abnormalities during pneumoperitoneum in children.

BACKGROUND: In adult patients, certain levels of PEEP (16 and 20 cm H(2)O) have been associated with left ventricular (LV) regional wall motion abnormalities. Since any increase in intra-abdominal pressure (IAP) exerted by a pneumoperitoneum is transmitted to the intrathoracic cavity, similar effects on LV regional wall motion cannot be ruled out. METHODS: To investigate the effects of pneumoperitoneum on LV regional wall motion, we performed a post hoc analysis of a transoesophageal echocardiography study in eight small children (mean age 3 yr, range 15-63 months) undergoing laparoscopic herniorrhaphy under anaesthesia with sevoflurane in nitrous oxide/oxygen and a PEEP of 5 cm H(2)O. During carbon dioxide insufflation, end-tidal carbon dioxide concentration ()was kept constant by increasing minute volume. RESULTS: An IAP of 12 mm Hg caused significant septal hypokinesia compared with baseline, while anterior and posterior wall motion was not affected. In addition, a lateral hyperkinesia occurred, though this change was not statistically significant. CONCLUSIONS: Pneumoperitoneum may affect LV regional wall motion in paediatric patients undergoing laparoscopic surgery.

Transoesophageal echocardiographic assessment of haemodynamic changes during laparoscopic herniorrhaphy in small children.

Laparoscopic techniques for surgery are gradually becoming established in paediatric surgery. Technical aspects, such as the maximum safe gas insufflation pressure, are still open to discussion. We used transoesophageal echocardiography to study the haemodynamic changes in eight small children undergoing laparoscopic herniorrhaphy, with two different levels of intra-abdominal pressure (IAP), 6 and 12 mm Hg. End-tidal carbon dioxide tension was maintained constant at 4.3-4.7 kPa. After baseline measurements, an IAP of 12 mm Hg was applied for 10 min. Next, IAP was decreased to 6 mm Hg, followed by a second period of 12 mm Hg. Haemodynamic measurements were obtained at each stage. A further measurement was obtained 10 min after abdominal deflation at the end of surgery while anaesthesia was unchanged. Cardiac index (CI) decreased significantly only after the first 12 mm Hg level of IAP. The subsequent decrease in IAP to 6 mm Hg caused return of CI to baseline levels. The second increase in IAP did not cause any reduction in CI. The initial reduction in CI, although statistically significant, did not appear to be clinically important. We conclude that an IAP of up to 12 mm Hg appeared to be safe in healthy small children undergoing laparoscopic herniorrhaphy.

Anesthetic considerations in pediatric laparoscopic and thoracoscopic surgery.

Minimally-invasive surgery does not equate with minimally-invasive anesthesia in children undergoing laparoscopic and thoracoscopic surgery. Knowledge of the associated pathophysiological changes, appropriate monitoring and good planning allow the safe provision of anesthesia for children subjected to these otherwise advantageous surgical techniques.

On-demand analgesia with piritramide in children. A study on dosage specification and safety.

The results of this study show that postoperative patient-controlled pain therapy in children with piritramide is - in a similar way as with adults - a safe method involving a low incidence of side effects. A special pump parameter setting is required with larger bolus dose sizes and longer lockout intervals, not very different from the experience gained with adults, and which is based on other values than those recommended up to now with morphine for paediatric PCA. Side effects were rarely observed. The fear of respiratory depression constitutes no rational reason to deny the younger patients this form of analgesia provided that monitoring is guaranteed.

[Results of Billroth I and Billroth II stomach resection]. / Ergebnisse von Magenresektionen nach Billroth I und Billroth II.

Between 1966 and 1986, Billroth I and Billroth II resections for gastroduodenal ulcers were performed at the Department of Surgery, Friedrich Schiller University, Jena. Early postoperative complications after Billroth II (14.6%) were somewhat rarer than after Billroth I (19.4%), however, bore a greater risk. With a permanent cure accounting for 85%, the comparison of both procedures reveals no significant differences in the late results. In gastric ulcer, Billroth's first method should be given preference because it can be carried out more rapidly in technical respect and takes digestive physiology into account.