Cerebral microcirculation during mild head injury after a contusion and acceleration experimental model in sheep.

BACKGROUND: Cerebral microcirculation after head injury is heterogeneous and temporally variable. Regions at risk of infarction such as peri-contusional areas are vulnerable to anaemia. However, direct quantification of the cerebral microcirculation is clinically not feasible. This study describes a novel experimental head injury model correlating cerebral microcirculation with histopathology analysis. OBJECTIVE: To test the hypothesis that cerebral microcirculation at the ischaemic penumbrae is reduced over time when compared with non-injured regions. METHODS: Merino sheep were instrumented using a transeptal catheter to inject coded microspheres into the left cardiac atrium, ensuring systemic distribution. After a blunt impact over the left parietal region, cytometric analyses quantified cerebral microcirculation and amyloid precursor protein staining identified axonal injury in pre-defined anatomical regions. A mixed effect regression model assessed the hourly blood flow results during 4 hours after injury. RESULTS: Cerebral microcirculation showed temporal reductions with minimal amyloid staining except for the ipsilateral thalamus and medulla. CONCLUSION: The spatial heterogeneity and temporal reduction of cerebral microcirculation in ovine models occur early, even after mild head injury, independent of the intracranial pressure and the level of haemoglobin. Alternate approaches to ensure recovery of regions with reversible injury require a targeted assessment of cerebral microcirculation.

Management of surgical patients on opioid replacement therapy: An audit of current practice.

Patients on opioid replacement therapy hospitalised with acute pain represent a clinical challenge and have poorer perioperative outcomes. There is limited evidence relating to acute pain management of this complex cohort. The primary objectives of this retrospective audit was to establish the number of patients who are admitted on opioid replacement therapy with an acute pain condition under surgical services and evaluate the management of these patients to determine consistency of pain management practices. Secondarily, we aimed to evaluate the documentation of opioid replacement therapy in clinical notes to determine adherence to operational protocols and record clinically relevant outcomes including infection or postoperative complication rates. Forty-four episodes of care for buprenorphine patients and 19 episodes of care for methadone patients were included. There was significant variability in inpatient opioid prescribing, including practice of dose modification, and there was high utilisation of additional opioids, although agent choice varied. Multimodal analgesia was utilised, especially following acute pain service review. There was an 11% readmission rate for complications of the initial presentation. Documentation at transitions of care was poor. There is a need for further clinical studies into specific acute pain management strategies, and their effect on clinically relevant outcomes, to guide consistent management practices.

The association between erector spinae plane block timing and reduced rib fracture related respiratory complications: A cohort study.

STUDY OBJECTIVE: Is erector spinae plane (ESP) catheter insertion within 24 h of hospital admission for rib fractures associated with a lower incidence of respiratory complications compared to those having an ESP within 48 h or after 48 h of admission. DESIGN: Retrospective cohort study. SETTING: Hospital. PATIENTS: 199 patients admitted for rib fractures, who received an ESP catheter. INTERVENTIONS: Timing of ESP performance was assessed by dividing the study cohort into three subgroups: prompt block within 24 h, early block within 48 h and late block after 48 h of admission. MEASUREMENTS: The primary outcome of interest was the development of respiratory complications. This included pneumonia, pulmonary embolism and respiratory failure. Secondary outcomes included intensive care unit (ICU) length of stay and hospital length of stay. MAIN RESULTS: A prompt ESP within 24 h was performed in 14.5% (n = 29) of patients, 47% (n = 95) received an early block within 48 h and 37% (n = 75) of patients received a late block after 48 h from admission. There was a significantly higher rate of respiratory complications (p = 0.005) with late block. A late block was associated with a significantly longer ICU length of stay (7.82 ± 5.2 days) compared to patients who received an early block (5.84 ± 2.8 days; p = 0.044). There was no significant association with hospital length of stay (p = 0.06). There were no differences between the prompt (within 24 h) and early (within 48 h) block groups for any outcome. CONCLUSIONS: The performance of an ESP block after 48 h of admission was associated with an increased incidence of respiratory complications and ICU length of stay. There appears to be no added benefit associated with the provision of a prompt ESP within 24 h.