Biomedical subjects

Helen I Opdam

Publications and source records attributed to Helen I Opdam.

4 recordsLinked to original sources

PubMed2006

Potential for organ donation in Victoria: an audit of hospital deaths.

OBJECTIVE: To determine the potential for organ donation in 12 Victorian hospitals. DESIGN AND SETTING: Prospective audit of all deaths in 12 major public hospitals in the state of Victoria between January 2002 and October 2004. MAIN OUTCOME MEASURES: Number of organ donors and potential organ donors (patients with brain death or likely to progress to brain death within 24 hours if supportive treatment continued), requests for organ donation and consents. Unrealised potential donors (organ donation not requested) were categorised by an independent panel of intensivists as category A (brain death formally diagnosed); B (brain death not formally diagnosed but criteria likely to be fulfilled); and C (potential to progress to brain death within 24 hours). RESULTS: There were 17,230 deaths, 280 potential organ donors and 220 requests for organ donation. The 60 unrealised potential organ donors were classified as category A (3), B (17) and C (40). Consent rate was 53% to 65%, depending on the definition of potential donor (categories A, B and C or category A only). Consent rate was lower when discussions about organ donation were held by trainees or registrars (21%) than when specialists were present (57%) (P = 0.004). A maximum practically achievable organ donation rate for Victoria was estimated to be 15 to 17 donors per million population (current rate, 9 per million population). CONCLUSIONS: The potential for organ donation in Victoria is limited by a small organ donor pool. There is potential to increase the number of organ donors by increasing the consent rate (lower than expected from public surveys), the identification of potential organ donors (particularly those likely to progress to brain death if supportive treatment is continued), and requests for organ donation.

Hospital Mortality↗

PubMed2006

Determining normal values for intra-abdominal pressure.

BACKGROUND: Intra-abdominal pressure (IAP) measurements can be used for the early detection and management of the abdominal compartment syndrome. IAP values are widely thought to be atmospheric or subatmospheric. However, there are no reports that describe normal IAP values using urinary bladder pressure measurements in patients not suspected of having a raised IAP level. This study sought to determine these normal values to aid our interpretation of IAP measurements in post-surgical patients or patients with suspected increased IAP. METHODS: Urinary bladder pressure measurements were carried out in 40 men and 18 women awake medical or non-abdominal surgery inpatients with existing indwelling catheters. Measurements were made in the supine, 30 degrees and 45 degrees sitting positions. Comparisons were carried out to determine the effects on urinary bladder pressure of body position, sex and a suspected diagnosis of benign prostatic hypertrophy. RESULTS: Median values for IAP were higher if measured in a more upright position (P < 0.0001). Median values were supine, 9.5 cmH2O (range, 1-18 cmH2O); 30 degrees upright, 11.5 cmH2O (range, 3-19 cmH2O); and at 45 degrees upright, 14.0 cmH2O (range, 4-22 cmH2O). Measurements recorded were neither atmospheric nor subatmospheric. IAP was higher in men compared with women in the supine and 30 degrees positions (P < 0.05) but not in the 45 degrees position (P = 0.083). There was no significant difference between patients with and without suspected benign prostatic hypertrophy. CONCLUSIONS: Normal IAP using urinary bladder pressure in awake patients are above atmospheric pressure. As a patient is moved from the supine into the upright position, IAP measurements increase.

Abdomen↗

PubMed2005

Brief breath holding may confound functional magnetic resonance imaging studies.

We demonstrate that breath holding of short durations may confound functional magnetic resonance imaging (fMRI) studies. Some subjects may hold their breath for a short time during task performance, especially if the task is challenging. Breath holding may therefore need to be considered specifically when interpreting fMRI experiments. We studied the temporal and spatial characteristics of cerebral T2*-weighted signal during short periods of breath holding by seven individuals in a 3-tesla MR scanner. We demonstrate that breath-holds as short as 3 s can result in regions of significant cerebral activation. More interestingly, we show that focal activation remains present when the data is analysed in a number of different ways, including analyses that correct for motion and model the task epoch as if it were 10 times longer than the actual breath-hold length. These findings have potential relevance for many researchers carrying out fMRI studies.

Adult↗

PubMed2002

A sheep model for the study of focal epilepsy with concurrent intracranial EEG and functional MRI.

PURPOSE: We describe a sheep model of penicillin-induced seizure activity using electroencephalography (EEG) and functional MRI (fMRI). METHODS: Ten adult sheep were used. Spikes and seizures were generated by instillation of 8,000-10,000 IU of penicillin into the right prefrontal cortex via a specially designed port. Bilateral intracranial EEG was acquired by using carbon fiber electrodes. Animals had behavioral characterization of their seizures and were then anesthetized for fMRI studies. Functional MRI was performed at 1.5 and 3 Tesla by measuring blood oxygen level-dependent (BOLD) weighted signal intensity at different times during the evolution of seizures. RESULTS: Behavioral seizures were associated with electrographic seizures. Intracranial EEG obtained in the MR scanner was of high quality. Focal spiking and seizures were seen in all animals and developed 11.3 +/- 11.2 s and 17.3 +/- 12.1 min after penicillin administration, respectively. An average of 13 +/- 4.8 seizures were seen per animal, each lasting 27.3 +/- 12.3 s. Functional MR images with little parenchymal artefact were obtained. Regional BOLD signal-intensity changes were observed during seizures at the seizure focus and ipsilateral amygdala. CONCLUSIONS: We have developed an animal model of partial epilepsy in which seizures can be reliably elicited with concurrent fMRI and intracranial EEG. During unilateral electrographic seizures, focal BOLD signal changes occurred at the seizure focus and ipsilateral amygdala, suggesting the presence of a cortico-subcortical loop. This observation illustrates the potential of the model for understanding seizure generation, spread, and possibly the consequences of repeated seizures on the brain.

Animals↗