Spinal cord ischemia-induced elevation of amino acids: extracellular measurement with microdialysis

Excitatory amino acids have been implicated in the production of calcium mediated neuronal death following central nervous system ischemia. We have used microdialysis to investigate changes in the extracellular concentrations of amino acids in the spinal cord after aortic occlusion in the rabbit. Glutamate, aspartate, glutamine, asparagine, glycine, taurine, valine, and leucine were measured in the microdialysis perfusate by high pressure liquid chromatography. The concentrations of glutamate, glycine, and taurine were significantly higher during ischemia and reperfusion than controls. Delayed elevations in the concentrations of asparagine and valine were also detected. The elevation of glutamate is consistent with the hypothesis that excitotoxins may mediate neuronal damage in the ischemic spinal cord. Increased extracellular concentrations of asparagine and valine may reflect preferential use of amino acids for energy metabolism under ischemic conditions. The significance of increased concentrations of inhibitory amino acid neurotransmitters is unclear.

Evaluation of a fiberoptic intracranial pressure monitor

The fiberoptic device is a relatively new type of intracranial pressure (ICP) monitor which appears to offer certain advantages over conventional monitoring systems, particularly its ability to measure brain parenchymal pressures. This study was undertaken to analyze the accuracy and drift characteristics of the fiberoptic device and to compare pressures in the subdural, intraparenchymal, and intraventricular compartments. The device was accurate to +/- 3 mm Hg over a 0- to 30-mm Hg range in vitro. The maximum daily drift was +/- 2.5 mm Hg, with an average daily drift of +/- 0.6 mm Hg and an average drift over a 5-day period of +/- 2.1 mm Hg. In vivo, the pressures and waveform characteristics obtained with the fiberoptic device and with a strain-gauge transducer connected to a ventriculostomy were very similar. Alterations in ICP were induced by various therapeutic and pathological manipulations, and the pressures in the three intracranial compartments were compared. Changes in ICP appeared to be reflected simultaneously and equally in all three compartments. Furthermore, changes in ICP secondary to a unilateral mass lesion were identical in both supratentorial parenchymal compartments when measured simultaneously. It is concluded that the fiberoptic device is an accurate and reliable system for ICP monitoring; the pressures recorded in the subdural, intraparenchymal, and intraventricular compartments paralleled each other in all of the physiological and pathological states tested. Although the drift associated with this device is less than that reported for previously available systems, its maximal cumulative drift over a 5-day period of +/- 6 mm Hg is significant. Since the fiberoptic device cannot be recalibrated in situ, it is suggested that the device be replaced if monitoring is to be continued for periods longer than 5 days.

Intravenous cocaine abuse and subarachnoid haemorrhage: effect on outcome

A retrospective study of subarachnoid hemorrhage associated with intravenous cocaine injection was undertaken in a large urban hospital. Patients who used intravenous cocaine had significantly poorer outcomes when compared with subarachnoid haemorrhage patients with no known exposure to the drug.

Reduction in spinal cord postischemic lactic acidosis and functional improvement with dichloroacetate

Pyruvate dehydrogenase complex (PDHC) is a major enzyme of glucose metabolism. Dichloroacetate (DCA) is a noncompetitive inhibitor of PDHC kinase, an enzyme that inactivates PDHC. We examined the effects of DCA on extracellular lactate and pyruvate concentration changes and spinal somatosensory evoked potentials (SSEP) in ischemic rabbit spinal cords. In the first group of 26 animals, the aorta was occluded until postsynaptic SSEP waves were completely suppressed for 10 min, a period of ischemia that causes neurologic deficits in 50% of untreated animals. DCA (25 mg/kg) was given to 13 of these animals before ischemia. In the second group of 24 animals, the aorta was occluded until the postsynaptic SSEP waves were absent for 20 min, a period of ischemia that produces paraplegia in 100% of untreated animals. DCA (25 mg/kg) was given to 16 of these animals just before the aortic occlusion was released. After occlusion, extracellular spinal lactate concentrations increased abruptly while pyruvate concentrations fell. Both lactate and pyruvate concentrations reached a plateau during the ischemic period but increased when the aortic balloon was deflated. DCA-treated animals had lower lactate and pyruvate peak concentrations during reperfusion, as well as more rapid and greater recovery of SSEP at 2 h after reperfusion. DCA did not alter spinal metabolism during the ischemia but appeared to produce a more rapid shift to glucose metabolism on reperfusion. Thus, DCA treatment resulted in better electrophysiological recovery after both moderate and severe ischemia, either by reducing lactic acidosis or by increasing the recovery rate of aerobic energy production.

Palliative therapy of malignant esophageal stricture with the bipolar tumor probe and prosthetic tube

Patients with malignant esophageal stricture and dysphagia were prospectively randomized to receive palliative therapy with the bipolar tumor probe (17) or prosthetic tube insertion (13). Both treatments gave good relief of dysphagia compared with pretreatment values on a dysphagia score, the results being statistically significant (p less than 0.005). However, there was no difference in the improvement achieved by one method compared with the other. The tumor probe was not difficult to use and complication rates were comparable. In the Atkinson tube group, two patients developed complications related to the position of the prosthesis and in three others food blocked the tube. Treatment with the tumor probe needed repeating at intervals (median, 28 days; range, 2 to 86 days) in all but four individuals to maintain palliation, with each patient needing a median of two treatments (range, 1 to 8). The probe may have advantages in very high esophageal lesions and may facilitate the treatment of tumor overgrowth or undergrowth of a tube. The prosthetic tube may give long-lasting relief of dysphagia and remains the treatment of choice for bronchopulmonary fistulas.

Clinical experience with a continuous monitor of intracranial compliance

Intracranial compliance, as estimated from a computerized frequency analysis of the intracranial pressure (ICP) waveform, was continuously monitored during the acute postinjury phase in 55 head-injured patients. In previous studies, the high-frequency centroid (HFC), which was defined as the power-weighted average frequency within the 4- to 15-Hz band of the ICP power density spectrum, was found to inversely correlate with the pressure-volume index (PVI). An HFC of 6.5 to 7.0 Hz was normal, while an increase in the HFC to 9.0 Hz coincided with a reduction in the PVI to 13 ml and indicated exhaustion of intracranial volume-buffering capacity. The mean HFC for individual patients in the present study ranged from 6.8 to 9.0 Hz, and the length of time that the HFC was greater than 9.0 Hz ranged from 0 to 104.8 hours. The mortality rate increased concomitantly with the mean HFC, from 7% when the mean HFC was less than 7.5 Hz to 46% when the mean HFC was 8.5 Hz or greater. The length of time that the HFC was 9.0 Hz or greater was also associated with an increased mortality rate, which ranged from 16% if the HFC was never above 9.0 Hz to 60% if the HFC was 9.0 Hz or greater for more than 12 hours. In 12 patients who developed uncontrollable intracranial hypertension or clinical signs of tentorial herniation during the monitoring period, 75% were observed to have had an increase in the HFC to 9.0 Hz or more 1 to 36 hours prior to the clinical decompensation. The more rapid the increase in the HFC, the more likely the deterioration was to be caused by an intracranial hematoma. Continuous monitoring of intracranial compliance by computerized analysis of the ICP waveform may provide an earlier warning of neurological decompensation than ICP per se and, unlike PVI, does not require volumetric manipulation of intracranial volume.

A double-blind dose ranging study of BRL 24924 and metoclopramide on lower oesophageal sphincter pressure in healthy volunteers

1. A double-blind placebo controlled dose ranging study of the effect of single oral doses of 1 and 2 mg BRL 24924 and 10 mg metoclopramide on lower oesophageal sphincter pressure has been performed in 20 healthy volunteers. 2. The 2 mg dose of BRL 24924 caused a statistically significant increase in mean lower oesophageal sphincter pressure (P less than 0.05) at 30-45 min post-dose (20.8 +/- 7.1 cm H2O BRL 24924; 16.4 +/- 5.7 cm H2O placebo). BRL 24924 1 mg and metoclopramide 10 mg failed to increase lower oesophageal sphincter pressure at any time. However, eight volunteers with a hypotensive resting lower oesophageal sphincter pressure (less than 15 cm H2O) showed a statistically significant rise in pressure at 120 min for both 1 mg, 2 mg (P less than 0.01; P less than 0.001) BRL 24924 and 10 mg metoclopramide (P less than 0.01). No other significant effect was detected on oesophageal manometry. 3. BRL 24924 (2 mg) has statistically significant effects on lower oesophageal sphincter pressure. However, further studies in patients with gastro-oesophageal reflux disease and oesophagitis are needed to evaluate its clinical efficacy, especially where a hypotensive lower oesophageal sphincter pressure predominates.

Alterations in the corticomotor evoked potential following spinal cord ischemia

A simple yet reliable model of spinal cord ischemia has been previously developed by inserting a Swan-Ganz catheter into the abdominal aorta of rabbits and inflating the balloon just inferior to the renal arteries. Recent investigations have shown that paraplegia is consistently reproduced if the balloon remains inflated for 20 min after loss of the N3 component of the somatosensory evoked potential. Because of its high reliability, this model has been frequently and successfully used to determine the efficacy of pharmacological agents thought to provide protection against spinal cord ischemia. Results from the present report demonstrate that a similar degree of reliability can be achieved in this model for testing motor activity. A simple method of evoking highly reproducible motor potentials, that can be percutaneously recorded from the spinal cord in response to cortical stimulation, was developed. Predictable and repeatable changes in the configuration of the corticomotor evoked potential were found during spinal cord ischemia and reperfusion. With this added dimension of functional assessment, future application of the current spinal cord ischemia model have been greatly expanded.

Quantitative assessment of the response to therapy in achalasia of the cardia

Radionuclide oesophageal transit studies and manometry have been carried out in 15 patients with achalasia of the cardia, before treatment, after a course of nifedipine and after pneumatic bag dilatation. Transit studies were also done in 10 patients after cardiomyotomy and in 10 normal subjects. Images were recorded with the subjects seated in front of a gamma camera while swallowing a 10 ml bolus of 99Tcm-tin colloid and then after a further drink of 50 ml water. There was marked retention of tracer in the oesophagus in patients with achalasia compared with rapid clearance in control subjects. Bag dilatation significantly reduced lower oesophageal sphincter pressure but there was no significant difference in the 50% clearance time or percentage dose retained at 100s before and after the treatments. Oesophageal clearance of tracer after the additional drink of water, was improved by bag dilatation. Oesophageal transit in the patients after cardiomyotomy was similar to that in patients who had undergone bag dilatation. There was considerable retention of the tracer in the oesophagus overnight, but this did not result in pulmonary aspiration. Radionuclide oesophageal transit studies provided a quantitative assessment of therapy in achalasia and the proportion of tracer retained after the additional drink proved to be a sensitive measure of response to treatment. Nifedipine proved ineffective as a treatment for achalasia. Bag dilatation and cardiomyotomy were of similar value.

Cardiovascular and metabolic responses to severe head injury

The cardiovascular and metabolic responses to severe head injury were studied in the acute phase after severe head injury with the object of determining if a common response was present and, if so, its significance in the management of the patients' intracranial and systemic physiological states. The cardiovascular response to head injury was studied by measurement of cardiac output, pulmonary capillary wedge pressure, arterial blood pressure, arterial and mixed venous blood gases and arterial and mixed venous epinephrine and norepinephrine serially in 15 patients during the first three days after injury. A hyperdynamic state was found characterized by increased cardiac output and cardiac work, moderate hypertension, tachycardia, decreased or normal systemic and pulmonary vascular resistance, increased pulmonary shunting and increased oxygen delivery and utilisation. Arterial E and NE levels correlated well with the cardiac output, cardiac work, blood pressure, heart rate, oxygen delivery, and oxygen utilization but not with vascular resistance or pulmonary shunt. The magnitude of the hyperdynamic state did not correlate with intracranial pressure, Glasgow Coma Score, or findings on CT scan. The metabolic response to head injury was studied by measurement of resting metabolic expenditure (RME) in 14 comatose head-injured patients in the first nine days after injury. During this period patients were fed with a continuous parenteral infusion of a formula containing 2 Kcal/cc and 10 mg nitrogen/liter. Indirect calorimetry was carried out for 102 patient-days. The mean resting metabolic expenditure (RME) for nonsedated, nonparalyzed patients was 138 +/- 37% of that expected for a non-injured resting person of equivalent age, sex, and body surface area. Nitrogen excretion was measured for 109 patient-days. The mean excretion was 20.2 +/- 6.4 mg/day. The mean protein caloric contribution was 23.9 +/- 6.7% and was greater than 25% for six patients, compared to normal values of 10-15%. Despite hyperalimentation, positive nitrogen balance for any 3-day period was achieved in only seven patients, and required replacement of 161% to 240% of RME with the parenterally administered formula. Head-injured patients had a metabolic response similar to that reported for patients with burns of 20-40% of the body surface.

Oesophageal transit of marshmallow after the Angelchik procedure

The oesophageal transit time of half a marshmallow was measured radiologically in 17 controls, 28 patients with gastro-oesophageal reflux pre-operatively, 36 patients soon after implantation of the Angelchik prosthesis (2-9 weeks) and in 23 patients later postoperatively (9-48 months). Sixteen postoperative patients also underwent oesophageal manometry. All control and pre-operative patients had a marshmallow transit time of less than 1 min; 67 per cent of the early postoperative patients had prolonged transit and 70 per cent of the late tests were similarly abnormal. Prolonged oesophageal transit as measured by marshmallow swallow correlated well with symptoms of solid food dysphagia. Most, but not all, patients with an abnormal marshmallow swallow had abnormal manometric findings. The oesophageal transit of solid food is significantly slowed after the Angelchik procedure and this is not a transient postoperative phenomenon.

Cerebral arteriovenous oxygen difference as an estimate of cerebral blood flow in comatose patients

The hypothesis that cerebral arteriovenous difference of oxygen content (AVDO2) can be used to predict cerebral blood flow (CBF) was tested in patients who were comatose due to head injury, subarachnoid hemorrhage, or cerebrovascular disease. In 51 patients CBF was measured daily for 3 to 5 days, and in 49 patients CBF was measured every 8 hours for 5 to 10 days after injury. In the latter group of patients, when a low CBF (less than or equal to 0.2 ml/gm/min) or an increased level of cerebral lactate production (CMRL) (less than or equal to -0.06 mumol/gm/min) was encountered, therapy was instituted to increase CBF, and measurements of CBF, AVDO2, and arteriovenous difference of lactate content (AVDL) were repeated. When data from all patients were analyzed, including those with cerebral ischemia and those without, AVDO2 had only a modest correlation with CBF (r = -0.24 in 578 measurements, p less than 0.01). When patients with ischemia, indicated by an increased CMRL, were excluded from the analysis, CBF and AVDO2 had a much improved correlation (r = -0.74 in 313 measurements, p less than 0.01). Most patients with a very low CBF would have been misclassified as having a normal or increased CBF based on the AVDO2 alone. However, when measurements of AVDO2 were supplemented with AVDL, four distinct CBF patterns could be distinguished. Patients with an ischemia/infarction pattern typically had a lactate-oxygen index (LOI = -AVDL/AVDO2) of 0.08 or greater and a variable AVDO2. The three nonischemic CBF patterns had an LOI of less than 0.08, and could be classified according to the AVDO2. Patients with a normal CBF (mean 0.42 +/- 0.12 ml/gm/min) had an AVDO2 between 1.3 and 3.0 mumol/ml. A CBF pattern of hyperemia (mean 0.53 +/- 0.18 ml/gm/min) was characterized by an AVDO2 of less than 1.3 mumol/ml. A compensated hypoperfusion CBF pattern (mean 0.23 +/- 0.07 ml/gm/min) was identified by an AVDO2 of more than 3.0 mumol/min. These studies suggest that reliable estimates of CBF may be made from AVDO2 and AVDL measurements, which can be easily obtained in the intensive care unit.

Palliation of malignant upper-third oesophageal stricture by bipolar diathermy probe

Bipolar thermocoagulation probes have been used to palliate dysphagia in six patients with an inoperable squamous cell carcinoma of the upper third of the oesophagus. Median dysphagia grade was improved following treatment, and the only serious complication was the development of a tracheo-oesophageal fistula in one patient. Bipolar thermocoagulation probes are an alternative treatment for malignant strictures of the upper third of the oesophagus, a group that may be difficult otherwise to palliate.

A study of the local toxicity of agents used for variceal injection sclerotherapy

Injection sclerotherapy is widely used in the treatment of oesophageal varices. However, few studies have compared the local toxicity of sclerosant agents which may be important if serious local complications are to be avoided. In this study the depth of injury caused by submucosal injection of increasing concentrations of sodium tetradecyl sulphate, polidocanol, 5% ethanolamine oleate and 5% varicosid in rabbits stomach, has been compared by histopathological examination. Macroscopic ulceration was seen in 14.6% of injection sites. Increasing concentrations of sodium tetradecyl sulphate and polidocanol produced increasingly extensive microscopic inflammation. Five percent varicosid caused more inflammation than 5% ethanolamine and only 3% polidocanol and 5% varicosid caused full thickness inflammation. Only 5% ethanolamine produced inflammation consistently confined to the mucosa and submucosa. On the basis of this study we feel that 5% ethanolamine is the most suitable agent for injection sclerotherapy.

Benign oesophageal stricture in Barrett's columnar epithelialised oesophagus and its responsiveness to conservative management

The response to treatment of peptic oesophageal stricture associated with columnar lined (Barretts) oesophagus (CLO) has been compared with that in peptic stricture without CLO. Benign oesophageal stricture was present in 23 (41%) of 56 patients consecutive with CLO. In 18 the stricture lay at the squamocolumnar mucosal junction and was associated with reflux oesophagitis, in five it was situated in the columnar lined segment and in four of these it was known to have been preceded by a chronic ulcer at the site of the stricture. Controls were an age and sex matched group of patients with benign stricture related to reflux oesophagitis unassociated with columnar epithelialisation. CLO associated strictures involving squamous mucosa were situated significantly (p less than 0.01) higher in the oesophagus than non-CLO strictures. The response to endoscopic dilatation and active medical treatment was significantly better, as judged by the need for subsequent dilatation (p less than 0.01) in the CLO than in the non-CLO group. It is concluded that associated columnar epithelialisation of the oesophagus is not in itself an indication for antireflux surgery in the management of benign stricture and these usually respond well to dilatation and medical treatment.

A double-blind placebo-controlled trial of BRL 24924 on lower oesophageal sphincter pressure and gastro-oesophageal reflux in healthy volunteers

BRL 24924 is a new gastrointestinal prokinetic agent with properties similar to metoclopramide but with increased potency and devoid of side-effects associated with blockade of dopamine receptors in the central nervous system. A double-blind placebo-controlled trial of the effect of a single oral dose of 2.2 mg BRL 24924 on lower oesophageal sphincter pressure and gastro-oesophageal reflux has been performed in 20 healthy volunteers. BRL 24924 significantly increased mean lower oesophageal sphincter pressure (21.9 cmH2O BRL; 15.9 cmH2O placebo: P less than 0.017) but failed to alter either the frequency or the duration of gastro-oesophageal reflux after provocation following a test meal. BRL 24924 has significant effects on lower oesophageal sphincter pressure but no effect on provoked post-prandial reflux in healthy volunteers. Further studies in patients with gastro-oesophageal reflux and oesophagitis are needed to evaluate the clinical efficacy of this compound.

Alterations in cerebral availability of metabolic substrates after severe head injury

Cerebral and systemic metabolism of oxygen, glucose, lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, and amino acids were studied in 27 comatose patients during the first 7 days after a head injury. Systemic oxygen consumption was elevated initially and gradually returned toward normal over the week of study. In contrast, cerebral oxygen consumption was depressed and decreased further over the week of study. Cardiac output and cerebral blood flow were increased with respect to systemic and cerebral metabolic requirements, and remained elevated for the entire week of study. Systemic hyperglycemia and lactic acidosis were present. The injured brain often made a sizeable contribution to the lactic acidosis. The arterial concentrations of pyruvate, beta-hydroxybutyrate and acetoacetate were low. The early postinjury arterial amino acid profile was typically an increased level of alanine, taurine, glutamic acid, and a reduced concentration of valine, leucine, isoleucine, threonine, serine, ornithine, and arginine. At 3-4 days postinjury, as the early abnormalities were returning toward normal, glutamine, lysine, phenylalanine, tyrosine, and methionine became elevated. These late increases in amino acids occurred at the time of the peak in plasma catecholamine concentrations. The net cerebral flux of amino acids followed the same general pattern of evolution over time as did the arterial concentration of amino acids. On days when the availability of the individual amino acid was increased, the net cerebral flux tended to be positive; when the availability was decreased, the net cerebral flux was zero or there was a net efflux of the amino acid. There was a significant linear relationship between the arterial concentration and the net flux of 13 of the 17 amino acids studied. Unlike the fasting state in normal man, in which beta-hydroxybutyrate and acetoacetate are important metabolic substrates, cerebral metabolism after head injury is almost totally dependent upon the aerobic and anaerobic metabolism of glucose. This is at least in part due to injury-induced limitations in the variety of substrates that are available for the brain to extract.

Value of endoscopic surveillance in the detection of neoplastic change in Barrett's oesophagus

Fifty-six patients with Barrett's oesophagus diagnosed between 1977 and 1986 were prospectively studied by 6-monthly endoscopic surveillance and biopsy. During follow-up to-date, four patients have developed high-grade dysplasia and three have adenocarcinoma of the oesophagus. Two of the adenocarcinomas were preceded by progressively severe dysplastic changes but in the third no dysplasia had been previously detected. The incidence of adenocarcinoma was 1 per 56 patient-years of follow-up. Changes in symptomatology or gross endoscopic appearances were usually absent, even after adenocarcinoma had developed, indicating that biopsy is essential for early diagnosis. The high risk of malignant change makes endoscopic surveillance advisable in all patients with Barrett's oesophagus.

Oesophageal transit of small tablets

Oesophageal transit has been studied in six asymptomatic subjects aged 29-80 years. Using gamma scintigraphy, the transit of a liquid and five small tablets was monitored in each subject. All the subjects exhibited normal liquid swallowing, with 50% oesophageal clearance times of less than 5 s. In three subjects all the tablets passed through the oesophagus within 6 s, but transit was prolonged in 60% of the swallows in the other subjects. Tablet hold up occurred more frequently in the elderly. An additional drink of water cleared all lodged tablets into the stomach. To minimize possible mucosal irritation, the taking of even small tablets should be followed by an additional drink of water.

Lung vascular permeability in patients with acute pancreatitis

Acute pancreatitis may be complicated by acute lung injury associated with increased lung vascular permeability to plasma protein. The pulmonary accumulation of the plasma protein transferrin, radiolabelled in vivo with indium-113m, was monitored using a portable probe radiation detector in sixteen patients with acute pancreatitis. Plasma protein accumulation (PPA) indices were within normal limits (less than 0.5 X 10(-3)min-1) in all survivors (n = 10) and elevated in all but one of the non-survivors. All non-survivors had severe acute pancreatitis as judged by standard criteria. Thus increased lung vascular permeability was not a constant feature of uncomplicated acute pancreatitis and was only observed in patients with multisystem failure accompanied by clinically evident acute lung injury.

Choice of therapy for achalasia in relation to age

Over an 11-year period 132 patients with achalasia underwent a total of 253 pneumatic bag dilatations of the cardia as the initial treatment. Adequate symptomatic relief was obtained in the majority, but 16 needed cardiomyotomy after pneumatic dilatation had failed to give lasting symptomatic relief. Older patients, aged 60 years or more, showed longer-lasting improvement with pneumatic dilatation than did younger ones and only 1 patient over 50 required cardiomyotomy. Benefit from pneumatic dilatation showed a closer relationship to age than to oesophageal diameter. Of 50 patients followed for more than 5 years, 48% required no further treatment, 40% needed at least one further dilatation to achieve symptomatic relief and 12% came to cardiomyotomy. This study suggests that pneumatic dilatation is safe, effective and particularly useful in the management of the elderly achalasic patient.

Protection against spinal cord ischemia with insulin-induced hypoglycemia

The effect of insulin-induced reduction in blood glucose to 65 +/- 20 mg/dl (mean +/- standard deviation) on recovery of electrophysiological function and extracellular lactate concentration was studied in a rabbit model of spinal cord ischemia. These results were compared to findings in animals with spinal cord ischemia that either were fasted overnight (fasted group: blood glucose 97 +/- 26 mg/dl) or had no pretreatment (control group: blood glucose 172 +/- 65 mg/dl). The aorta was occluded until the postsynaptic waves of the spinal somatosensory evoked potentials (SSEP's) had been absent for 20 minutes, a period of ischemia that produces paraplegia in 100% of untreated rabbits. The total aortic occlusion time was not significantly different in the three groups. Recovery of the SSEP's was significantly better in the insulin-treated animals than in the fasted or control animals. The N3 wave of the SSEP's, which has been found to correlate best with neurological recovery, returned to 65% +/- 48% of the preischemia amplitude in the insulin-treated animals, compared to 40% +/- 34% in the fasted group and 26% +/- 24% in the control animals. Extracellular lactate concentration in the spinal cord increased immediately after occlusion of the aorta, reached a plateau as the postsynaptic waves disappeared from the SSEP's, and then increased a second time during the first 15 minutes of reperfusion. The peak lactate concentration during ischemia and during reperfusion correlated with the preischemia glucose concentration (r = 0.60336 and r = 0.76930, respectively). Lactate concentration in the spinal cord was higher during ischemia and throughout the first 2 hours of reperfusion in the control and fasted animals than in the insulin-treated animals. During the 2nd hour of reperfusion, lactate concentration was significantly higher in the control animals than in the fasted animals. Reduction in blood glucose with insulin improves recovery of electrophysiological function after spinal cord ischemia, probably because of reduced lactic acid production, especially during the early reperfusion period.

The predictive value of cerebral anaerobic metabolism with cerebral infarction after head injury

Cerebral ischemia is a common mechanism of secondary brain injury following severe head injury. The cerebral metabolic rate of oxygen (CMRO2) and of lactate (CMRL), as well as cerebral blood flow (CBF) were measured daily for 5 days after head injury in 44 comatose head-injured patients to determine if metabolic changes could identify the patients who would develop cerebral infarction. Of 41 patients whose CBF remained at levels regarded as adequate to prevent infarction (CBF greater than or equal to 0.2 ml/gm/min), the six who showed a cerebral infarction on computerized tomography (CT) scans exhibited characteristic cerebral metabolic patterns: a CMRO2 of less than 0.6 mumol/gm/min on one or more of the days monitored, and markedly elevated cerebral lactate production (CMRL less than -0.06 mumol/gm/min) on Days 1 and/or 2 after injury. Patients who had no areas of infarction on serial CT scans typically had a CMRO2 and CMRL can be obtained at the bedside and can indicate the presence of an evolving ischemic infarct after head injury.

National survey of use of the Angelchik antireflux prosthesis

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Vagal function in achalasia of the cardia

Autonomic nervous function in achalasia of the cardia was assessed by measuring the response of the lower oesophageal sphincter to abdominal compression, the gastric secretory response to insulin-induced hypoglycaemia and the pulse rate variability with deep respiration. Twenty-eight patients with symptomatic achalasia and 24 age and sex-matched control subjects were studied. Rise in intra-abdominal pressure normally causes a rise in lower oesophageal pressure through a vagally-mediated mechanism. Before treatment this response was unimpaired in eight of 10 patients with achalasia. A sub-normal response was found in eight of 10 patients who had previously had pneumatic dilatation of the cardia and in three of four who had had a cardiomyotomy. These abnormalities reflected the effect of treatment in disrupting the sphincter rather than impairment of its innervation. The gastric acid secretory response to insulin-induced hypoglycaemia, expressed as a ratio of that to pentagastrin, was normal in each of the nine patients studied. Pulse rate variability with deep respiration, a test of cardiac vagal function, was normal in 22 of 25 patients studied. It is concluded that in achalasia the vagal trunks appear functionally intact and that the myenteric plexus lesion rarely affects the responsiveness of the lower oesophageal sphincter to increase in intra-abdominal pressure.

Biliary pharmacokinetics of sulbactam plus ampicillin in humans

The biliary pharmacokinetics of sulbactam and ampicillin was investigated in 19 patients with normal liver function who were undergoing surgery of the biliary tract. The combination of sulbactam (0.5 g) plus ampicillin (1 g) was given intravenously to five patients with T-tube drainage of the common bile duct. Mean peak concentrations of sulbactam (19.4 micrograms/ml) and ampicillin (471 micrograms/ml) in the bile occurred 0.5-1 hr after administration. Biliary excretion was estimated to account for approximately 0.24% of the sulbactam dose and 2.8% of the ampicillin dose. Fourteen other patients received the same dose of sulbactam/ampicillin immediately before elective cholecystectomy. Respective mean concentrations of sulbactam and ampicillin at the time of gallbladder removal were 4.3 micrograms/ml and 15.9 micrograms/ml in gallbladder bile and 6.3 micrograms/g and 7.7 micrograms/g in gallbladder wall tissue. These results, together with the antibacterial spectrum and potency of the combination, suggest that sulbactam/ampicillin is suitable for prophylactic use in biliary tract surgery.

Assessment of nutritional requirements of head-injured patients

A nomogram is presented for estimation of energy expenditure at the bedside in comatose patients during the first 2 weeks after brain injury. In analysis of 312 days of energy expenditure in 57 patients, a combination of Glasgow Coma Scale (GCS) score, heart rate (HR), and days since injury (DSI) was found with multiple regression analysis to provide good prediction of resting metabolic expenditure (RME) according to the following relationship: %RME = 152 - 14(GCS score) + 0.4(HR) + 7(DSI) (n = 111, r = 0.7, p less than 0.001). In non-comatose patients, predictive ability was less strong due to inability to measure truly rested values, but HR and GCS score could be used to predict energy expenditure by this relationship: %RME = 90 - 3 (GCS score) + 0.9 (HR) (n = 135, r = 0.47, p less than 0.001). In six patients, paralysis was found to decrease energy expenditure to between 100% and 125% of expected. Movement or stimulation had little effect on energy expenditure in patients who could localize stimuli but increased rested values by 20% in posturing patients. Analysis of fasted balance periods of nitrogen excretion in 22 patients based on 273 days of measurement showed a significant relationship between creatinine-height index (an index of muscle mass) and nitrogen excretion, but no relationship between nitrogen excretion and weight, temperature, and RME. Levels of retention of nitrogen with feeding could not be predicted by any of these variables. Feeding of the individual comatose patient is best guided at present by estimation of energy expenditure using a nomogram and periodic measurement of urinary nitrogen excretion.

Protection against experimental ischemic spinal cord injury

The authors have studied the protection against ischemic damage to rabbit spinal cord by pretreatment with agents that block neuronal activity and directly or indirectly reduce tissue metabolism. Hypothermia, thiopental, magnesium, lidocaine, and naloxone were used to pretreat the spinal cord prior to ischemia. Hypothermia and thiopental provided comparable protection: they each increased the duration of ischemia required to produce neurological deficits in 50% of the animals from 26 to 41 minutes. They also increased from 10 to 30 minutes the time that the postsynaptic waves of the spinal somatosensory evoked potential (SSEP) could be absent and the animal still have neurological recovery. Hypothermia and thiopental, when used together, increased the duration of ischemia required to produce neurological deficits to 57 minutes in 50% of the animals. Naloxone increased the duration of ischemia required to produce neurological deficits to 36 minutes in 50% of the animals, and increased to 20 minutes the time that the postsynaptic waves of the SSEP could be absent and the animal still have neurological recovery. Magnesium pretreatment improved neurological outcome, possibly by improving collateral circulation as the SSEP did not fail completely during aortic occlusion in all animals. Lidocaine was not beneficial, perhaps because of the prolonged hypotension that resulted.

Steroid administration and nitrogen excretion in the head-injured patient

The effect of steroid administration on metabolic rate and nitrogen excretion was examined in 20 head-injured patients alternately assigned to receive either methylprednisolone for 14 days or no steroid treatment. Although metabolic rate, caloric intake, and nitrogen intake were not different between the two groups, the patients who received steroids had a 30% higher excretion of nitrogen during the first 6 days after injury than did the patients not receiving steroids. All patients had an increase in nitrogen excretion through the 2nd week, peaking on Day 11. By Day 21 after injury, the patients had an average cumulative nitrogen loss of 162 gm and had lost an average of 5 kg body weight regardless of whether they had received steroids. Serum albumin levels decreased in the steroid-treated patients but returned to nearly normal by Day 21 in the untreated group. Immunosuppression, evidenced by a lower initial total lymphocyte count and a higher incidence of infections, was present in the steroid group; hyperglycemia requiring insulin treatment was more common in those patients.

Enteral hyperalimentation in head injury

The objectives of this study were to determine the ability of enteral hyperalimentation to meet the caloric and protein requirements in acute severe head injury, and to study the effect of increasing protein intake on nitrogen balance. This consecutive series of 20 patients suffered acute severe head injury and remained comatose for at least 24 hours. They were all without other major injuries, and were treated with steroids. These patients were randomly placed in two comparable treatment groups: one group was fed with an enteral formula containing 14% of its calories as protein and the other group received a formula containing 22% protein calories. Feedings were advanced to replace 140% of caloric expenditure measured by indirect calorimetry, averaging 3500 kcal/24 hr. Balance periods of the targeted intake were 7 days in duration, and were begun during the 1st week after injury for 65% of patients and in the 2nd week after injury for 35% of patients. The lower protein group received an average of 26.8 gm/24 hr of nitrogen, equivalent to 188 gm of protein, and the higher protein group 34.3 gm/24 hr, equivalent to 231 gm of protein. Nitrogen balance was -9.2 +/- 6.7 gm/24 hr in the lower protein group and -5.3 +/- 5.0 gm/24 hr in the higher protein group, but the difference did not reach statistical significance because of sample size and variability in extent of catabolism among patients. Despite the hyperalimentation, there was a mean negative cumulative nitrogen balance of 200 gm by the 2nd week after injury, and only three patients achieved net nitrogen equilibrium for the 7-day balance period. Despite enteral hyperalimentation, the patients' weight fell by 15% in the 2nd week, serum albumin was often decreased, and creatinine-height index decreased over time but remained in a normal range. Monitoring urinary urea nitrogen, which has been advocated as a generally available technique for measuring urinary nitrogen concentration, was found to be a poor measure of urinary nitrogen excretion. This work has demonstrated: 1) that high caloric and protein feedings may be delivered for prolonged periods enterally for most patients in the acute phase of head injury with few metabolic complications, and 2) that increasing the nitrogen content of feedings from 14% to 22% may somewhat improve nitrogen retention, although nitrogen equilibrium is seldom achieved.

Oxygen utilization and cardiovascular function in head-injured patients

Factors that influenced resting metabolic expenditure (RME) and the cardiovascular response associated with an elevated RME were examined in 55 patients with penetrating and closed head injuries who were kept normovolemic and hyperalimented during the acute phase of injury. The severity of the neurological injury had a strong effect on the RME; those with a GCS of 4-5 had the highest RME, 168 +/- 53% of that expected, whereas those with a GCS of 6-7 had a lower RME, 129 +/- 31% of that expected. Increased body temperature was associated with increased RME by 45%/degrees C in patients with a GCS of 4-5 and by 15%/degrees C in those with a GCS 6-7. The increase in oxygen utilization was associated with an increase in plasma catecholamines. Sedatives, paralyzing agents, and propranolol all decreased RME. The cardiovascular response associated with increased oxygen utilization was an elevated cardiac output and, when RME was very high, a widened mean arterial-venous oxygen content difference, indicating that the tissues were more fully extracting oxygen. The increased cardiac output was dependent upon the presence of an adequate intravascular volume. During the 2-year period of study, a total of 99 patients with closed head injuries (including 44 patients who underwent studies) were admitted. The mortality rate of this consecutive series of comatose patients was 25%. The incidence of intracranial hypertension (30%) and of death from uncontrolled intracranial hypertension (12%) was not different from that reported in other recent series.(ABSTRACT TRUNCATED AT 250 WORDS)

The metabolic response to severe head injury

Caloric expenditure and nitrogen balance were measured in 14 steroid-treated comatose head-injured patients acutely and up to 28 days after injury. During this period patients were fed with a continuous enteral infusion of a formula containing 2 Kcal/cc and 10 gm nitrogen/liter. Indirect calorimetry was carried out for 102 patient-days. The mean resting metabolic expenditure (RME) for nonsedated nonparalyzed patients was 138% +/- 37% of that expected for an uninjured resting person of equivalent age, sex, and body surface area. Nitrogen excretion was measured for 135 patient-days. The mean excretion was 20.2 +/- 6.4 gm/day. The mean protein caloric contribution was 23.9% +/- 6.7% and was greater than 25% for six patients, compared to normal values of 10% to 15%. Despite hyperalimentation, positive nitrogen balance for any 3-day period was achieved in only seven patients, and required replacement of 161% to 240% of RME with enterally administered formula. Head-injured patients had a metabolic response similar to that reported for patients with burns of 20% to 40% of the body surface.

Aneurysmal bone cyst of the rib

Aneurysmal bone cysts are uncommon lesions, especially in the ribs. Four patients with aneurysmal bone cysts of the rib are presented and previously reported cases reviewed. A brief discussion of the clinical manifestations, pathology, aetiology, and current treatment of aneurysmal bone cyst is also included.

Cardiovascular response to severe head injury

The cardiovascular, pulmonary, and metabolic responses to severe head injury were studied clinically in the acute phase after severe head injury with the object of determining if a common response was present and, if so, its significance in the management of the patients' intracranial and systemic physiological states. Cardiac output, pulmonary capillary wedge pressure, arterial blood pressure, arterial and mixed venous blood gases, and arterial and mixed venous epinephrine (E) and norepinephrine (NE) levels were measured serially in 15 patients during the first 3 days after injury. A hyperdynamic state was found, characterized by increased cardiac output, cardiac work, moderate hypertension, tachycardia, decreased or normal systemic and pulmonary vascular resistance, increased pulmonary shunting, and increased oxygen delivery and utilization. Arterial E and NE levels correlated well with the cardiac output, cardiac work, blood pressure, heart rate, oxygen delivery, and oxygen utilization but not with vascular resistance or pulmonary shunt. The magnitude of the hyperdynamic state did not correlate with intracranial pressure, Glasgow Coma Scale score, or computerized tomography findings. It is concluded that a hyperdynamic cardiovascular state occurs after severe head injury, and that it is mediated in part by sympathetic nervous activity. The significance of this state for systemic management of patients with head injury is discussed.

Treatment of hypertension associated with head injury

Arterial hypertension that occurs after severe head injury is characterized by elevation of systolic blood pressure, tachycardia, increased cardiac output, normal or decreased peripheral vascular resistance, and increased circulating catecholamines. The effects of two drugs used in the management of hypertension, propranolol and hydralazine, on these indices of cardiovascular function were examined in six head-injured patients. Both drugs effectively normalized blood pressure. However, hydralazine increased heart rate by 30%, cardiac index by 49%, left cardiac work by 21%, and pulmonary venous admixture by 53%, and was responsible for an increase in intracranial pressure or decreased compliance in two patients. Hydralazine produced no consistent change in arterial catecholamines. In contrast, propranolol decreased heart rate by 21%, cardiac index by 26%, left cardiac work by 35%, pulmonary venous admixture by 15%, and oxygen consumption by 18%. Propranolol decreased arterial epinephrine levels by 48% and norepinephrine levels by 28%. Propranolol appears to be a useful antihypertensive drug in the hyperdynamic head-injured patient because it normalizes blood pressure and the underlying hemodynamic abnormalities both by its beta-adrenergic blocking action and by decreasing circulating levels of catecholamines.

Failure of histidine supplementation to improve anemia in chronic dialysis patients

Failure of histidien supplementation to improve anemia in chronic dialysis patients was seen in six patients after a study period of 8 weeks. Serum amino acid levels were elevated to normal by supplementation with 1 g of oral histidine/day in all patients. There was no significant change in serum iron or transferrin levels, hematocrit, or red cell mass in five of the six patients. Histidine supplementation may raise serum amino acid levels, but does not cause any increase in red cell mass or improve the anemia in patients on chronic dialysis who are ingesting adequate dietary protein.

A radiological study of morphology and growth in the human fetal colon

A radiological study has been made of the colon in 64 human fetuses between 11 and 20 weeks gestation (64-160 mm crown rump (CR) length). A dynamic picture of colon development was obtained from analysis of the radiographs. The findings challenge textbook descriptions, but can be interpreted in terms of the ultimate morphology of the colon. According to the morphology of the proximal (pre-splenic) part of the colon, there are three types of colon. In Type 1 it lies transversely, in Type 2 it is oblique in direction, and Type 3 has a postnatal form with ascending and transverse elements. Although the Type 1 predominates in smaller fetuses and the type 3 is most common in larger fetuses, there is some overlap in their distribution. The ileocaecal junction does not descend, but actually slightly ascends as the fetus grows. The splenic flexure grows in a distinctly cranial direction, and at almost three times the rate of the ileocaecal junction. Thus, as the fetus develops, the ileocaecal junction and splenic flexure grow further apart, and this determines the change from a Type 1 to a Type 2 colon. The divergence of the ileocaecal junction and splenic flexure appears to be related to different rates of growth in the colon, the distal (post-splenic) part growing almost half as fast again as the proximal (pre-splenic) part. The more mature (Type 3) form of colon appears to result from conversion of the Type 2 following early adhesion between the proximal colon and the second part of the duodenum.

Magnetic Bays at Macquarie Island

Polar magnetic bays are the most striking feature of magnetic records obtained by the Australian National Antarctic Research Expeditions at Macquarie Island. Negative bays are more numerous than positive bays and have greater amplitudes and durations. As a rule, negative bays commence about magnetic midnight whereas positive bays commence about 5 hr earlier. A daily reversal in direction of the bayproducing currents is indicated and the time at which this reversal takes place appears to vary with the seasons. During magnetically disturbed periods the ratio H bay amplitude to Z bay amplitude increases, indicating a northward movement of the bay-producing currents. At the same time auroras seen from Macquarie Island lie further north in the sky than usual.