Metabolic Tissue Swelling and Local Microcirculation in Splanchnic Artery Occlusion Shock: Implications for Critical Illness

Trauma is a leading cause of death in the United States. Advancements in shock resuscitation have been disappointing because the correct upstream mechanisms of injury are not being targeted. Recently, significant advancements have been shown using new cell-impermeant molecules that work by transferring metabolic water from swollen ischemic cells to the capillary, which restores tissue perfusion by microcirculatory decompression. The rapid normalization of oxygen transfer improves resuscitation outcomes. Since poor resuscitation and perfusion of trauma patients also causes critical illness and sepsis and can be mimicked by ischemia-reperfusion of splanchnic tissues, we hypothesized that inadequate oxygenation of the gut during trauma drives development of later shock and critical illness. We further hypothesized that this is caused by ischemia-induced water shifts causing compression no-reflow. To test this, the superior mesenteric artery of juvenile anesthetized swine was occluded for 30 minutes followed by 8 hours of reperfusion to induce mild splanchnic artery occlusion (SAO) shock. One group received the impermeant polyethylene glycol 20,000 Da (PEG-20k) that prevents metabolic cell swelling, and the other received a lactated Ringer's vehicle. Survival doubled in PEG-20k-treated swine along with improved macrohemodynamics and intestinal mucosal perfusion. Villus morphometry and plasma inflammatory cytokines normalized with impermeants. Plasma endotoxin rose over time after reperfusion, and impermeants abolished the rise. Inert osmotically active cell impermeants like PEG-20k improve intestinal reperfusion injury, SAO shock, and early signs of sepsis, which may be due to early restoration of mucosal perfusion and preservation of the septic barrier by reversal of ischemic compression no-reflow. SIGNIFICANCE STATEMENT: Significant advancements in treating shock and ischemia have been disappointing because the correct upstream causes have not been targeted. This study supports that poor tissue perfusion after intestinal ischemia from shock is caused by capillary compression no-reflow secondary to metabolic cell and tissue swelling since selectively targeting this issue with novel polyethylene glycol 20,000 Da-based cell-impermeant intravenous solutions reduces splanchnic artery occlusion shock, doubles survival time, restores tissue microperfusion, and preserves gut barrier function.

Changes in intraocular pressure during low dose intravenous sedation with propofol before cataract surgery

AIMS

This study examined the effects on intraocular pressure, pulse rate, and blood pressure of low dose intravenous sedation with propofol.

METHODS

Twenty adult patients who were scheduled to undergo cataract surgery were given a single intravenous bolus (0.98 (SEM 0.4) mg/kg) of propofol for sedation before administering the local anaesthetic for cataract surgery. A small intravenous dose of lignocaine was the only other anaesthetic or sedative agent given. The intraocular pressure in the non-surgery eye, the pulse rate, and the blood pressure were measured before and after propofol induction.

RESULTS

Compared with the preinduction baseline, there was a 17% to 27% (from 16.2 (0.7) mm Hg to 11.8 (0.7) mm Hg) decrease in intraocular pressure after propofol induction. A significant decrease in intraocular pressure occurred within the first minute and was still evident at 7 minutes when the measurements were stopped. There was also a 7%-12% increase in pulse rate during the first 4 minutes, a 12% decrease in mean systolic blood pressure, and a 7% decrease in mean diastolic blood pressure from baseline after propofol induction.

CONCLUSION

A single low dose bolus of propofol used for sedation before cataract surgery caused a moderate reduction in intraocular pressure with minimal, easily managed side effects.

Thyroid carcinoma

The mode of presentation, initial findings, treatment, and survival in differentiated thyroid carcinoma were studied in 155 patients. The classic signs, symptoms, and scan findings were present in approximately 70 per cent of the patients, with the remaining 30 per cent displaying unusual manifestations or findings. The effects of neck metastases, extracapsular invasion, and recurrent laryngeal nerve involvement on long-term survival were studied in detail. Prognosis was dependent more on age at initial appearance than any other factor. Patients with prior exposure to radiation had more extensive disease and required more extensive surgery, but they ultimately had the same prognosis for 10-year cure. Treatment of distant metastatic disease by surgery, radioactive iodine, and external radiation resulted in long-term survival in certain cases.