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Biomedical subjects

T Madsen

Publications and source records attributed to T Madsen.

At least 55 records · Page 3Linked to original sources
PubMed1986

Acid gastro-oesophageal reflux episodes as related to the quality of preceding peristalsis. A study in normal subjects.

It has earlier been demonstrated after long-term monitoring of pH and peristalsis in the oesophagus that episodes of acid gastro-oesophageal reflux occur in normal volunteers. To determine whether there is a connection between gastro-oesophageal reflux and prior peristalsis, pH and peristalsis were monitored for 12 h in 26 asymptomatic subjects. The recorded peristalsis was divided into brief bursts of peristaltic contractions (less than or equal to 60 sec) and more prolonged continuous activity. Peristaltic periods were limited to prior and subsequent peristalsis by a non-peristaltic course of greater than 30 sec. Continuous peristalsis was defined as a sequence of peristaltic contractions with a mutual distance between individual peristaltic waves of greater than or equal to 30 sec. A total of 81 episodes of reflux were recorded, of which 67 were preceded by peristaltic activity. Brief bursts of peristalsis, unrelated to reflux episodes, were frequently terminated by bolus-transporting peristaltic waves (p less than 0.001). When the last contraction before reflux was considered, an increased frequency of non-propagating peristalsis was found (p less than 0.01). In addition, a closer time relationship was observed between peristalsis and reflux if the last contraction was of the upper segmentary type, as compared with propagating activity (p less than 0.001). In conclusion, reflectory sphincter relaxation producing reflux may possibly be triggered by contractions in the upper part of the oseophagus, not followed by a bolus-transporting peristaltic wave.

Adult↗
PubMed1985

Experimental analysis of Hoffmann external fixation in various mountings.

The mechanical properties of four different configurations of the Hoffmann external fixation system were tested in an experimental setup using 4-mm stainless steel pins. Furthermore, stainless-steel pins and titanium pins 5 mm in diameter were applied in one of the fixators. The evaluation of the results was based on a paired t-test, with P less than 0.05 as the significance level. The quadrilateral transfixing Hoffmann-Vidal frame (HVF) proved to be the most rigid fixator under all loading conditions. The unilateral frame type supplied with two connecting bars and four ball joints was significantly more rigid than the unilateral single-bar device. By increasing the pin diameter from 4 to 5 mm a further increase of stiffness could be achieved, thus reaching about two-thirds of the rigidity of the HVF. The difference between titanium and stainless steel pins was not significant. Common for all the frame mountings was a fivefold greater rigidity in the lateral direction (in the plane of the pins) than in the anteroposterior direction (perpendicular to the pins).

Biomechanical Phenomena↗
PubMed1985

Effect of domperidone on gastro-oesophageal function in normal human subjects.

The aim of the study was to investigate gastro-oesophageal function in normal volunteers after oral administration of domperidone as a single dose (20 mg). The study was designed as a double-blind cross-over investigation. Ten healthy men (aged 27-50 years; median, 30) joined the study. Oesophageal function tests were performed, starting 1.5 h after intake of domperidone or placebo. Gastro-oesophageal sphincter pressure was measured with a perfused catheter system and a continuous pull-through technique. No changes in sphincter pressure were found. Peristaltic pressure amplitude in the body of the oesophagus and the duration and velocity of peristalsis were measured after wet swallows (bolus 5 ml of water). No changes were found. Intragastric pH did not change significantly after domperidone. No effect of domperidone on the results of a standard acid-clearing test could be found. Plasma concentrations of domperidone did not correlate with any of the other variables. In conclusion, domperidone given orally in a dose that has been shown to accelerate gastric emptying does not influence gastro-oesophageal sphincter pressure or peristaltic activity in the normal oesophagus.

Adult↗
PubMed1984

Holding power of different screws in the femoral head. A study in human cadaver hips.

The holding power of four different bone screws was measured by a pull-out test in 40 cadaver hips from 10 females and 10 males over 70 years of age. Each femoral head was used to test a 6.5 mm cancellous bone screw and a 12.7 mm hip compression screw. The holding power was higher in screws with a long or wide thread. Generally, the holding power in bones from females was about 70 per cent of that in bones from males.

Aged↗
PubMed1983

Gastro-oesophageal function in normal subjects after oral administration of ranitidine.

The aim of the study was to investigate gastro-oesophageal function in normal subjects after oral administration of 150 mg ranitidine as a single dose. The study was designed as a double blind crossover investigation. Ten healthy men, aged 26-49 years (median 29 years) joined the study. A series of oesophageal function tests were performed, starting 90 minutes after oral intake of ranitidine or placebo. Gastro-oesophageal sphincter pressure was measured using a perfused catheter system and a continuous pull-through technique. No changes in sphincter pressure could be demonstrated. Peristaltic amplitude in the body of the oesophagus as well as the duration and velocity of the peristalsis were measured after wet swallows (bolus 5 ml of water). We found no changes in these variables. Intragastric pH was measured and was higher after ranitidine than after placebo (p less than 0.005). Plasma ranitidine concentration did not correlate with intragastric pH. No effect of ranitidine could be demonstrated on the results of a standard acid clearing test. It is concluded that ranitidine, given orally in sufficient doses to suppress gastric acid secretion, does not influence gastro-oesophageal sphincter pressure or peristaltic activity in the oesophagus of normal subjects.

Adult↗
PubMed1983

Oesophageal peristalsis in normal subjects. Influence of pH and volume during imitated gastro-oesophageal reflux.

Acid gastro-oesphageal reflux in normal human subjects is followed by oesphageal peristalsis. The aim of the present study was to investigate the influence of pH and volume during imitated reflux on oesophageal peristalsis. Fluid volumes of 2.5, 5, 10, and 15 ml (pH 1.0, 4.0, or 7.0) were instilled randomly in the lower end of the oesophagus in eight healthy subjects. Further, repeated instillations were carried out in one subject. Oesophageal pressures were measured 5, 10, and 15 cm oral to the gastro-oesophageal sphincter and in the pharynx, and pH 5 cm oral to the sphincter. Peristalsis confined to the oesophagus was found to be related to the volume of the instilled fluid, whereas pharynx-mediated peristalsis seemed to be related to the acidity of the fluid. It is concluded that peristalsis after imitated gastro-oesophageal reflux is influenced by both the volume and the acidity of the instilled fluid. Volume seems to initiate a local clearing mechanism, whereas low pH initiates pharynx-mediated peristalsis.

Adult↗
PubMed1983

Axial compression in femoral neck osteotomies. A biomechanic study in human cadaver hips.

The risk of applying compression to a sliding-screw-plate osteosynthesis in the treatment of femoral neck fractures was evaluated in an experimental study of 40 femoral neck osteotomies. Ten pairs of bones from autopsied women between 70 years and 79 years of age were compared to 10 pairs of bones from autopsied women of more than 80 years of age. The compression was applied intermittently but measured continuously. The results showed a diphasic curve. When the maximum axial compression force was reached, any attempt to apply further compression resulted in a rapid fall in pressure at the site of the osteotomy. The median of the maximum axial compression force was 971 N, ranging from 275 N to 1756N. The maximum axial compression forces were significantly lower in bones from women of more than 80 years of age compared to bones from women in the seventh decade. The clinical implication of the study is that compression of femoral neck fractures by a sliding-screw-plate system may be hazardous in patients with brittle bone, e.g. women over 80 years of age.

Age Factors↗
PubMed1982

Spontaneous peristaltic activity in the oesophagus after imitated acid gastro-oesophageal reflux. A study in normal subjects.

Prolonged measurements of pH and peristalsis in the oesophagus do not enable quantitation of the reflux material. Eight healthy subjects underwent 12-h continuous pH and pressure recording in the oesophagus and, subsequently, recording of pH and spontaneous peristaltic activity after instillation of 0.1 N HCl. Volumes of 2.5, 5, 10, and 15 ml were instilled in the lower end of the oesophagus in randomized order. No relationship between volume and peristaltic activity could be demonstrated. A direct relationship between the change in pH after instillation and the peristaltic activity was demonstrated (r = 0.8052; p less than 0.001). The clearing efficiency was 0.3 pH units per peristaltic contraction. A similar relationship could be found between the change of pH during a spontaneous reflux episode and the following peristaltic activity (r = 0.5993; p less than 0.002). The clearing efficiency was 0.37 pH units per peristaltic contraction. It is concluded that low pH is the determining factor for eliciting oesophageal peristalsis.

Adult↗
PubMed1982

Failures after surgical treatment of patients with hiatus hernia and reflux symptoms. A pathophysiological study.

Patients treated surgically for hiatus hernia and reflux symptoms may still have reflux symptoms at follow-up examination, even though relapse of the hernia cannot be demonstrated on X ray. In an attempt to explain the causes of surgical failures, a group of 13 patients with persisting reflux symptoms after a modified Belsey MK IV repair for sliding hiatus hernia and reflux symptoms underwent intraluminal oesophageal manometry, acid clearing test, and 12-h continuous pH recording in the lower part of the oesophagus. None of the patients had radiological relapse of the hernia. The results of these tests, pre- and post-operatively, were compared with the results obtained in a group of successfully treated patients and with normal subjects. No differences of clinical importance could be demonstrated between the two patient groups with regard to the preoperative test results. Postoperatively, the 'failures' had low sphincter pressure, prolonged acid clearing, and pathological acid reflux. The tests seem of little value in the prediction of symptomatic failures, but do to some extent explain the symptoms of surgical 'failures'.

Adolescent↗
PubMed1981

Fourier-analysis of peristaltic pressure variations in the oesophagus during a 12-hour investigation. A study in normal subjects.

Long-term measurements have been made of peristaltic pressure variations 8 and 23 cm proximally to the gastro-oesophageal sphincter. The investigation was performed using perfused catheter systems and results of the 12-h measuring period were recorded on tape recorder. The peristaltic pressure variations were frequency analysed using a Fast Fourier Transform analyser. Nineteen normal subjects took part in the study. One subject was tested seven times. The investigation showed that the significant information regarding the pressure variations can be registered by recording systems with an upper frequency limit of at least 2 Hz. The pressure variations were built up more rapidly proximally in the organ than distally. Repeated investigations on a single subject showed that the intravariation lies within the intervariation in the subjects tested.

Adult↗
PubMed1980

Acid-sensitive oesophagus.

The aim of the present study was to investigate whether any differences could be demonstrated between patients with reflux symptoms and an acid-sensitive oesophagus (group I) (positive acid perfusion test) and a matched control group of patients with reflux symptoms and an acid-insensitive oesophagus (group II) (negative acid perfusion test) with respect to other oesophageal function tests (manometry, acid clearing and acid reflux (12-h continuous pH recording)). The two groups consisted of 47 and 46 patients, respectively. No differences were demonstrated between the two groups with respect to gastro-oesophageal sphincter pressure, acid-clearing ability, and acid reflux (irrespective of the criterion used for reflux). From the study it may be concluded that not only hydrochloric acid but other components of the reflux material may be responsible for producing symptoms of gastro-oesophageal reflux.

Adult↗
PubMed1980

Intraluminal oesophageal manometry. Influence of pressure probe diameter.

The influence of the pressure-probe diameter on the values of gastro-oesophageal sphincter pressure, pharyngo-oesophageal sphincter pressure, and peak peristaltic pressure in the oesophageal body was investigated in eight healthy subjects. A low-compliance perfused pressure-measuring unit was used for the recordings. Three different probes were made with external diameters of 1.5 mm, 3.5 mm, and 4.5 mm. Sphincter pressures were measured in the resting state, and peristaltic pressures were measured during wet swallows. The pressure in the sphincter regions was found to depend on the diameter of the probe, whereas the peak peristaltic pressure amplitudes were independent of the probes used. The need for standardization of manometry equipment is emphasized.

Adult↗
PubMed1979

Effect of non-carbonic acidosis on total splanchnic perfusion and cardiac output during anaesthesia with O2-N2O-barbiturate-relaxant.

Seven dogs were anaesthetized using mebumal natrium-O2-N2O-gallamonijdidum. The PaCO2 was kept at a constant level by means of mechanical ventilation, and non-carbonic acidosis was induced with HCl infusion (0.3 normal). The arterial pH varied from 7.45 to 6.88. During this acidosis, a rising arterio-venous oxygen difference was observed, with an unchanged total oxygen consumption. The pulse fell, but the mean pressures in the right atrium and aorta were unchanged. The peripheral resistance rose by 50%, whereas the fall in cardiac output of 20% was non-significant (0.10 greater than P greater than 0.05). The total splanchnic perfusion fell by 28%, and the change in flow was correlated to the change in pH. Total splanchnic perfusion (ml min-1) = -4078+655x pH (N = 42, r = 0.67, P less than 0.001). Total splanchnic perfusion as a fraction of the cardiac output remained unchanged. The resistance in the splanchnic area rose by 50%. The oxygen saturation in the portal vein and mixed venous blood changed in parallel. It is concluded that contraction of the blood vessels is the most important effect on the circulation resulting from non-carbonic acidosis during the anaesthesia employed here.

Abdomen↗
PubMed1979

Effect of non-carbonic acidosis on total splanchnic perfusion and cardiac output during anaesthesia with O2-N2O-halothane.

Six dogs, premedicated with pethidine 10 mg kg-1 b.w, were anaesthetized with mebumal natrium (NFN) 25 mg kg-1 b.w. and 80 mg gallamoni jodidum (NFN). Anaesthesia was continued with O2-N2O-halothane and artificial ventilation. Non-carbonic acidosis was induced by i.v. infusion of hydrochloric acid, during which the related values of pulse, blood pressure, cardiac output, total splanchnic prefusion and portal pressure were measured. The pulse remained unchanged down to pH 7.0. At this pH, arrhythmia suddenly occured and developed into ventricular fibrillation. Before this occured falling cardiac output was observed (cardiac output 1 min-1 = -21.49+3.21 x pH, N = 23, r = 0.75, P less than 0.001) and rising oxygen consumption (O2 ml min-1 kg-1 = 25.79--2.96 x pH, N =28, r = 0.52, P less than 0.01), rising oxygen extraction and rising peripheral resistance, while the mean pressure in the aorta was almost unaltered. During this course towards circulatory failure, an unchanged to slightly rising total splanchnic perfusion (Qsp1) was demonstrated, which with the lowest pH, represented up to 40% of the cardiac output (Qtot): Qsp1/Qtot = 3.11--0.39 x pH (N = 28, r = 0.52, P less than 0.01). Portal pressure rises slightly during acidosis, and oxygen saturation in the portal vein is high. It is probable that the retained splanchnic blood flow is caused by retention of the portal flow. This is quite different from observations during anaesthesia with barbiturates. It is concluded that halothane modifies considerably the circulatory response in the systemic circulation and the splanchnic region during non-carbonic acidosis.

Abdomen↗
PubMed1979

The influence of cimetidine on basal gastro-oesophageal sphincter pressure, intargastric pH, and serum gastrin concentration in normal subjects.

A pressure and pH-sensitive probe has been constructed for simultaneous measurement of gastro-oesophageal sphincter pressure and intragastric pH. The coefficient of variation for measurements of the gastro-oesophageal sphincter was 0.24, and for the intragastric pH, 0.09. After peroral ingestion of 400 mg of cimetidine or placebo, simultaneous measurements of gastro-oesophageal sphincter pressure and intragastric pH were made at fixed time intervals, and at the same time blood samples were taken for determination of serum gastrin and serum cimetidine concentrations. No demonstrable difference was found in the time-course of the gastro-oesophageal sphincter pressure after ingestion of cimetidine or placebo. After ingestion of cimetidine a significant rise in intragastric pH (p less than 0.05) occurred after 40 min, and this increased pH was maintained for the remainder of the experimental period, corresponding to a serum cimetidine concentration of over 1.00 mg/l. Similarly, there was a significant rise (p less than 0.05) in serum gastrin concentration after 150 min. There was a significant direct correlation between corresponding measurements of intragastric pH and serum gastrin (p less than 0.001), between intragastric pH and serum cimetidine (p less than 0.001), and between serum gastrin and serum cimetidine (p less than 0.05). Ingestion of cimetidine results in an increase in the serum gastrin concentration in healthy subjects, presumably as a result of reduced secretion of acid in the stomach. Neither the endogenous increase in serum gastrin concentration nor the increase in intragastric pH causes alteration in the gastro-oesophageal sphincter pressure.

Adult↗
PubMed1979

12-Hour simultaneous registration of acid reflex and peristaltic activity in the oesophagus. A study in normal subjects.

Twelve-hour simultaneous registration of acid gastro-oesophageal reflux and peristaltic activity in the oesophagus was carried out on 30 healthy subjects. The intensity of the acid gastro-oesophageal reflux was determined by automatic integration of the pH variation. Acid gastro-oesophageal reflux to pH less than or equal to 4 occurs in normal subjects within a range of 0--2.4% of the total registration period. The intravariation was measured in 10 investigations on 1 subject, and lay within the intervariation. To maintain the pressure-measuring system intact, 3 ml H2O/h were fed to the proximal and distal pressure catheters, respectively; it has been shown that this small quantity of water has no influence on the pH variation. Peristaltic activity for the entire measuring period was recorded and related to the individual reflex episodes. The total activity was found to be dependent on the level of consciousness, with little activity occurring during sleep. A positive correlation was found between the lowest pH during a reflux episode and the peristaltic activity in the oesophagus (p less than 0.001), between the lowest pH during a reflux episode and the duration of the reflux episode (p less than 0.001), and between the peristaltic activity and the duration of the reflux episode (p less than 0.001). During long-term registration of oesophageal pH it appears that pH less than or equal to 4 is a usable parameter for distinguishing between pathological and non-pathological acid gastro-oesophageal reflux. Sudden falls in pH to below 4 release increased peristalsis in the oesophagus.

Adult↗