Biomedical subjects

I Pearson

Publications and source records attributed to I Pearson.

10 recordsLinked to original sources

PubMed1995

Incidence and effects of increased cerebral blood flow velocity after severe head injury: a transcranial Doppler ultrasound study I. Prediction of post-traumatic vasospasm and hyperemia.

Cerebral blood flow velocity was monitored in 50 patients with severe head injury (GCS 8 or less) within 24 h of injury and at least once daily thereafter, using transcranial Doppler ultrasonography (TCD). Delayed post-traumatic vasospasm occurred in 20, and cerebral hyperemia in another 15. Doppler velocities were higher in vasospasm, which also lasted significantly longer than hyperemia. The presence of visible blood on an early CT scan was of some value in predicting vasospasm only (accuracy 59%). Xenon-133 cerebral blood flow (CBF) was also measured within 24 h of injury. An abnormal early cerebral blood flow level, either above or below a narrow central range, was more effective than CT in predicting vasospasm or hyperemia (accuracy 80%), while the combination of an abnormal blood flow and hemorrhagic findings on CT scan helped to determine which of these would occur later. Patients with an abnormal early cerebral blood flow and hemorrhagic findings on CT were more likely to develop vasospasm--accuracy for prediction of vasospasm 73%. This distinction may be of great importance, since these different groups of patients may well need different management.

Adolescent↗

PubMed1993

Dynamic cardiomyoplasty in chronic left ventricular failure: an experimental model.

Dynamic cardiomyoplasty continues to attract interest as a therapeutic option in the management of heart failure. In a large animal model of ischemic heart failure, we have compared dynamic cardiomyoplasty with both adynamic cardiomyoplasty and a control group. Heart failure was induced by coronary artery ligation in sheep, and under the same anesthetic dynamic cardiomyoplasty (n = 5), adynamic cardiomyoplasty (n = 4), or no further procedure was performed (n = 5). After recovery the animals were housed for a further 3 months. The dynamic cardiomyoplasty underwent a recognized muscle transformation protocol during this period. At terminal studies, the animals were hemodynamically assessed, both under baseline conditions and after colloid volume loading. The data at baseline were compared with unpaired t tests, and the function curves created by volume loading were compared by analysis of variance. Although the changes at baseline were small, there were highly significant improvements in the function curves in the dynamic cardiomyoplasty group when the stimulators were turned on compared with stimulators off (p = 0.005) for cardiac output; p = 0.035 for left ventricular end-diastolic pressure; p = 0.002 for pulmonary artery capillary wedge pressure; p = 0.004 for stroke volume; and p = 0.003 for cardiac power). There were also significant improvements in indices of cardiac performance when the dynamic cardiomyoplasty group was compared with both the control and adynamic cardiomyoplasty groups. We conclude that there is experimental evidence that cardiomyoplasty augments cardiac function in a model of chronic left ventricular failure.

Animals↗

PubMed1991

Experimental model of left ventricular failure.

A model of chronic cardiac failure has undergone extensive hemodynamic investigation. Under anesthesia the homonymous and second diagonal coronary arteries of sheep have been ligated. The resulting myocardial infarction caused significant acute hemodynamic impairment (paired two-tailed t tests), mean pulmonary artery pressure increasing from 7.31 +/- 0.94 to 13.80 +/- 1.19 mm Hg (p less than 0.001), pulmonary artery diastolic pressure increasing from 4.94 +/- 1.03 to 11.13 +/- 1.27 mm Hg (p less than 0.001), and directly measured left ventricular end-diastolic pressure increasing from 9.31 +/- 1.52 to 17.42 +/- 1.82 mm Hg (p less than 0.001) after infarction documented with invasive monitoring. There was a hemodynamically significant left ventricular aneurysm (paired two-tailed t tests) in animals studied 3 months later, with increased mean pulmonary artery pressure from 7.20 +/- 1.15 to 13.80 +/- 2.00 mm Hg (p = 0.009), an increase in pulmonary artery diastolic pressure from 4.60 +/- 1.30 to 12.10 +/- 2.06 mm Hg (p = 0.006), and an increase in left ventricular end-diastolic pressure from 11.00 +/- 1.94 mm Hg before infarction to 17.00 +/- 2.69 mm Hg (p = 0.038). We conclude that this is a useful model of chronic left ventricular failure that is reproducible and applicable to investigations of therapeutic options in chronic heart failure.

Animals↗

PubMed1991

Transcranial Doppler ultrasound in brain death: experience in 140 patients.

The interpretation of clinical tests for brain death is often complicated by the presence of facial trauma, or the use of barbiturate therapy for reduction of intracranial pressure. We propose a non-invasive technique--transcranial Doppler (TCD) sonography for the diagnosis of brain death. One hundred and forty comatose patients, 111 of whom were believed to be brain dead underwent TCD examinations. TCD assessments of the middle cerebral arteries (MCAs) and the basilar artery were performed before formal clinical testing for brain death. The TCD spectra recorded in the brain dead (BD) patients consisted of short, sharp systolic peaks followed by retrograde flow during diastole or just systolic peaks with absent flow in either direction. There were no survivors among patients who displayed these two TCD patterns. The 29 comatose control patients always showed flow throughout the cardiac cycle--no retrograde flow was ever recorded in these patients all of whom survived. Of particular interest were the basilar artery results. In nine BD patients no MCA signals could be obtained while good quality signals were recorded from the basilar artery. The TCD results agreed essentially with 100% accuracy with clinical testing and four vessel cerebral angiography. This paper illustrates the usefulness of TCD examination of the MCAs and especially the basilar artery in the diagnosis of brain death.

Adolescent↗

PubMed1991

Goal directed therapy with dobutamine in a porcine model of septic shock: effects on systemic and renal oxygen transport.

Systemic and renal haemodynamic and functional indices were measured in 15 anaesthetised pigs during systemic sepsis induced by faecal peritonitis. Five animals were assigned to maintenance of cardiac output (CO) at baseline, pre-infection values throughout the study (controls n = 5). In the remaining 10 animals, CO was increased by 25% prior to induction of sepsis and maintained at this level for the duration of the study using volume expansion with intravenous colloid and an infusion of either 20 micrograms/kg/min dobutamine (n = 5) or placebo (n = 5). Hourly measurements were made of CO, left renal blood flow, arterial and renal venous oxygen saturation, urine output, creatinine clearance and arterial partial pressure of oxygen until the animal died or until termination 8 h. Systemic indices of oxygen transport did not reflect the behaviour of the renal vascular bed during the management of sepsis. In the dobutamine group systemic oxygen uptake (VO2) increased from 173 +/- 30 to 277 +/- 73 ml/min (P less than 0.05), however this resulted in a decrease in renal DO2 (20 +/- 9 to 10 +/- 2 ml/min P less than 0.05) and there was no equivalent rise in renal VO2 (3.3 +/- 1.6 to 3.2 +/- 1.5 ml/min). There was however no significant difference in the effect on renal function of the three management protocols. Agents used to increase cardiac output during systemic sepsis may result in significantly different effects on the renal vascular bed which are not revealed by the measurement of systemic indices alone.

Animals↗

PubMed1990

The hospital trauma team: a model for trauma management.

A triage system was established as the initiating mechanism for a trauma team response to assist the assessment and early management of patients presenting to an accident and emergency department. A checklist of triage criteria was used. During a 6-month period, 342 patients (29.7% of trauma admissions) satisfied the triage criteria, which should have resulted in an average of 1.9 trauma team calls per day. Staff compliance with the triage tool was 75.4%. The overtriage rate for the checklist criteria was 52.7%. The triage tool identified patients with severe injuries who were not initially considered sufficiently injured to justify initiation of the trauma team response. The sensitivity of the triage tool in identifying patients with serious injury was 95.0%. Comparison of the review with a similar review performed 12 months earlier demonstrated that staff compliance with initiating the trauma team response had improved. Using data from 564 patients from both series, logistic regression analysis of the power of the triage criteria to predict serious injury contributed to a revision of the triage criteria. This trauma triage tool and trauma team response constitute a valid approach to the early hospital management of trauma patients. This system may be more appropriate or achievable in many hospitals than the construction of dedicated trauma reception units or permanent surgical staffing of general Accident and Emergency departments.

Adolescent↗

PubMed1989

Implementation of a trauma team.

A team approach to the initial assessment, investigation and management of potentially seriously injured patients has been instituted. Team members are alerted through an emergency paging system which is activated when a patient fulfills one of a predetermined list of criteria relating to the injury incident, physiological status of the patients and anatomic injuries. Medical members of the team include surgical, intensive care, anaesthetic, and accident and emergency staff. The surgical representative acts as team co-ordinator. Aspects of the function of the trauma team system were assessed over 4 months during which time 721 injured patients were admitted, 240 patients satisfied the trauma team criteria, and the team was called 152 times. The observed 'false alarm' rate was 38% but the true false alarm rate would have been 46%. Injuries sustained by some patients, who satisfied the criteria but who were not evaluated by the team, were of sufficient severity to justify a greater compliance with the system than was observed at this early stage after its implementation. Although a false alarm rate of 46% is higher than desirable, the number of calls per day would still only average 2 in a hospital with a high trauma patient load. The checklist criteria were highly sensitive (97%) in identifying those patients who should have been evaluated by the trauma team. Although hospitals differ in workload and staffing, this trauma team model is recommended for more widespread use and for further evaluation and modification.

Adolescent↗

PubMed1988

Sepsis associated with central vein catheters in critically ill patients.

In 440 critically ill patients, the association between different central vein catheter insertion sites, the duration of catheter insertion and catheter-associated sepsis was examined. Of 780 catheter tips studied, 19% were colonized by microorganisms. The incidence of colonization varied with the different insertion sites. The lowest percentage of colonized catheters occurred with catheters inserted via the subclavian vein (15%) and the highest, at the femoral vein insertion site (34%, p less than 0.01). The percentage of catheters colonized increased as the duration of insertion increased, at all insertion sites studied. Catheter colonization was closely related to the development of bacteraemia and was associated with approximately 10% of colonized catheters. Our results suggest that the subclavian site is associated with the lowest infective complication rate. To minimize catheter associated sepsis, catheters at all insertion sites should be used with parsimony and only kept in place for the minimum amount of time that their continuing use is necessary.

Catheterization, Central Venous↗

PubMed1985

Ingestion of hydrochloric acid.

A case of intentional ingestion of concentrated acid, in which both disseminated intravascular coagulation and acute respiratory insufficiency complicated initial resuscitation, is reported. The assessment and the acute management of this unusual problem are reviewed, with emphasis on early endoscopy and laparotomy.

Adult↗

PubMed1983

[Not Available].

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Academies and Institutes↗