Biomedical subjects

Jane Griffith

Publications and source records attributed to Jane Griffith.

4 recordsLinked to original sources

PubMed2005

Cerebral autoregulation and ageing.

Little is known about the effects of ageing on cerebral autoregulation (CA). To examine the relationship between age and CA in adults, we conducted a prospective study using a non-invasive protocol without external stimuli. We studied 32 subjects, aged 23-68 years. They were assigned to a young group (28+/-5 years) and an old group (54+/-8 years). The groups were sex-matched. Transcranial Doppler ultrasonography (TCD) was used to record bilateral middle cerebral artery flow velocities (CBFV, cm/sec). Noninvasive beat-to-beat tonometric arterial blood pressure (ABP) measurement of the radial artery was used to record spontaneous blood pressure fluctuations. The Mx, an index of dynamic cerebral autoregulation (dCA), was calculated from a moving correlation between ABP and CBFV. We did not find a correlation between age and Mx. No statistically significant difference in the Mx between the groups (0.27+/-0.23, young, vs. 0.37+/-0.24, old) was demonstrated. Age does not affect dynamic cerebral autoregulation assessed by the Mx index in healthy adult subjects. This study supports findings from previous papers wherein CA was measured with protocols which require external stimuli. Further studies are needed to determine CA in subjects above 70 years of age.

Adult↗

PubMed2003

Hemispheric asymmetry and temporal profiles of cerebral pressure autoregulation in head injury.

A moving correlation index (Mx-ABP) between arterial blood pressure (ABP) and mean middle cerebral artery blood flow velocity (CBFV) can be used to monitor dynamic cerebrovascular autoregulation (CA) after traumatic brain injury (TBI). In this study we examined hemispheric CA asymmetry and temporal CA profiles, their relationship with ABP and CBFV, and their prognostic relevance. Mx-ABP was calculated for each hemisphere in 25 TBI patients second-daily for as long as they were receiving sedation and analgesia. Forty-nine recordings were obtained, between one and six per patient. Four time periods were defined: immediate--postinjury days (PID) 0 and 1; early--PID 2 and 3; intermediate--PID 4 and 5, and late--PID 6 and later. GOS was estimated at discharge, GOS 4 and 5 were considered favorable (15 patients) and GOS 1-3 unfavorable outcome (10 patients). A Mx difference >0.2 was classified as hemispheric asymmetry (HA). HA was observed at least once in 12 of the 25 patients (48%) and in 18 of 49 recordings (37%). It was observed during all time periods: 35%, 43%, 25%, 43%, respectively, and was not related to outcome. There was no difference in mean CBFV or ABP between patients with and without HA. HA was not related to interhemispheric CBFV differences. A significant improvement in Mx was seen over time. Hemispheric CA asymmetry is common after traumatic brain injury. It does not bear significant clinical or predictive relevance, and it is unrelated to CBFV or ABP. CA is most profoundly disturbed during the immediate postinjury phase and improves gradually during the ICU course. Further studies are needed to investigate CA during post ICU recovery and rehabilitation.

Adolescent↗

PubMed2003

Noninvasive cerebrovascular autoregulation assessment in traumatic brain injury: validation and utility.

A moving correlation index (Mx-CPP) of cerebral perfusion pressure (CPP) and mean middle cerebral artery blood flow velocity (CBFV) allows continuous monitoring of dynamic cerebral autoregulation (CA) in patients with severe traumatic brain injury (TBI). In this study we validated Mx-CPP for TBI, examined its prognostic relevance, and assessed its relationship with arterial blood pressure (ABP), CPP, intracranial pressure (ICP), and CBFV. We tested whether using ABP instead of CPP for Mx calculation (Mx-ABP) produces similar results. Mx was calculated for each hemisphere in 37 TBI patients during the first 5 days of treatment. All patients received sedation and analgesia. CPP and bilateral CBFV were recorded, and GOS was estimated at discharge. Both Mx indices were calculated from 10,000 data points sampled at 57.4Hz. Mx-CPP > 0.3 indicates impaired CA; in these patients CPP had a significant positive correlation with CBFV, confirming failure of CA, while in those with Mx < 0.3, CPP was not correlated with CBFV, indicating intact CA. These findings were confirmed for Mx-ABP. We found a significant correlation between impaired CA, indicated by Mx-CPP and Mx-ABP, and poor outcome for TBI patients. ABP, CPP, ICP, and CBFV were not correlated with CA but it must be noted that our average CPP was considerably higher than in other studies. This study confirms the validity of this index to demonstrate CA preservation or failure in TBI. This index is also valid if ABP is used instead of CPP, which eliminates the need for invasive ICP measurements for CA assessment. An unfavorable outcome is associated with early CA failure. Further studies using the Mx-ABP will reveal whether CA improves along with patients' clinical improvement.

Adolescent↗

PubMed2003

The epidemiology of diabetes in the Manitoba-registered First Nation population: current patterns and comparative trends.

OBJECTIVE: This study provides an overview of the epidemiology of diabetes in the Manitoba First Nation population. RESEARCH DESIGN AND METHODS: The study uses data derived from the population-based Manitoba Diabetes Database to compare the demographic and geographic patterns of diabetes in the Manitoba First Nation population to the non-First Nation population. RESULTS: Although the prevalence of diabetes rose steadily in both the First Nation and the non-First Nation populations between 1989 and 1998, the epidemiological pattern of diabetes in these two populations differed significantly. The First Nation population was observed to have age-standardized incidence and prevalence rates of diabetes up to 4.5 times higher than those found in the non-First Nation population. The sex ratio and the geographic patterning of diabetes incidence and prevalence in the two study populations were reversed. CONCLUSIONS: The results of the study suggest that diabetes prevalence will likely continue to rise in the Manitoba First Nation population into the foreseeable future, and that the impact of this rising diabetes prevalence can only be effectively managed through a population-based public health approach focusing on primary and secondary prevention. The dramatically higher rates of diabetes in Manitoba First Nation population as compared with the non-First Nation population highlight the urgency of this activity. These prevention efforts need to be supported by further research into the reasons for the unique epidemiological patterns of diabetes incidence and prevalence in the First Nation population observed in this study. These include investigating why First Nation populations living in the Northern areas of the province seem to be protected from developing high rates of diabetes and why First Nation women experience much higher rates of the disease.

Adult↗