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Biomedical subjects

C S Robertson

Publications and source records attributed to C S Robertson.

At least 145 records · Page 8Linked to original sources
PubMed1988

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.

Adolescent↗
PubMed1988

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.

Acute Disease↗
PubMed1988

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.

Adult↗
PubMed1988

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.

Adult↗
PubMed1988

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.

Adult↗
PubMed1988

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.

Adolescent↗
PubMed1987

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.

Adult↗
PubMed1987

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.

Animals↗
PubMed1987

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.

Adult↗
PubMed1986

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.

Animals↗
PubMed1986

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.

Adolescent↗
PubMed1985

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.

Adult↗
PubMed1985

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.

Adult↗
PubMed1984

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.

Adolescent↗