Vascular Infusion Research Articles

Neonatal Cardiac Mesenchymal Stromal Cells Promote Recovery of Infarcted Myocardium through CD44 Mediated FoxP3+ T-Regulatory Cells after Vascular Infusion

Intravenous infusion has been used as the method of cell delivery in many preclinical studies as well as in some early clinical trials. Among its advantages are broad distribution, ability to handle a large-volume infusion, and ease of access. Progenitor cells used in cell-based therapy act through their secretomes, rather than their ability to differentiate into lineage-specific cell type. Since not all progenitor cells have similar secretome potency, the innate abilities of the secretome of cells used in clinical trials will obviously dictate their effectiveness. We previously found that cardiac neonatal mesenchymal stromal cells (nMSCs) are more effective in repairing the infarcted myocardium compared to adult mesenchymal stromal cells (aMSCs) due to their robust secretome (Sharma et al Circulation Research 120:816–834, 2017). In this study, we explored the efficacy of intravenous (IV) delivery of nMSCs for myocardial recovery. Six-week-old male Brown Norway rats underwent acute MI by ligation of the left anterior descending artery, followed by IV infusion of cell dose 5 × 106 nMSCs/rat body weight (kg) or saline on days 0 and 5. We found that cardiac parameters in the rodent ischemia model improved 1 month after nMSCs infusion, and the result is comparable with the intramyocardial injection of nMSCs. Tracking the infused cells in target organ revealed that their movement after IV delivery was mediated by the cell surface receptor CD44. Systemic injection of nMSCs stimulated immunomodulatory responses specifically by increasing FoxP3+ T-regulatory cell influenced anti-inflammatory macrophages (M2) in heart. These data demonstrate that nMSCs promote immunogenic tolerance via CD44-driven T-reg/M2 stimulation that helps nMSCs for longer viability in the injured myocardium for better functional recovery. Our data also demonstrate a rationale for a clinical trial of IV infusion of nMSCs to promote cardiac function improvement in the ischemic patients.Graphical

Submental island flap - should we be worried about lymph node transfer? An anatomical and histological study

The submental island flap has been increasing in popularity for both oncological and non-oncological reconstruction of the head and neck. However, the original description of this flap left it with the unfortunate designation as a lymph node flap. There has thus been significant debate on the oncological safety of the flap. In this cadaveric study the perforator system suppling the skin island is delineated and the lymph node yield of the skeletonised flap is analysed histologically. A safe and consistent approach to raising the perforator flap modification is described and the pertinent anatomy, and an oncological discussion with regards to the submental island perforator flap histological lymph node yield discussed. Ethical approval was received from Hull York Medical School for the anatomical dissection of 15 sides of cadavers. 6 x 4cm submental island flaps were raised following a vascular infusion of a 50/50 mix of acrylic paint. The flap size mimics the T1/T2 tumour defects these flaps would usually be used to reconstruct.The submental vascular anatomy, including length, diameter, venous drainage patterns, and the skin perforator system was documented. The dissected submental flaps were then histologically examined for the presence of lymph nodes by a head and neck pathologist at Hull University Hospitals Trust department of histology. The total length of the submental island arterial system, the distance from where the facial artery branches off from the carotid to the submental artery perforator entering the anterior belly of digastric or skin, averaged 91.1mm with anaverage facial artery length of 33.1mm and submental artery of 58mm. Vessel diameter for microvascular reconstruction was 1.63mm for the submental artery and 3mm for the facial artery. The most common venous anatomy drainage pattern was the submental island venaecomitantes draining to the retromandibular system then to the internal jugular vein. Almost half the specimens had a dominant superficial submental perforator allowing the ability to raise this as a skin only system. There were generally 2-4 perforators passing through the anterior belly of digastric to supply the skin paddle.73.3% (11/15) of the skeletonised flaps contained no lymph nodes on histological examination. The perforator version of the submental island flap can be safely and consistently raised with inclusion of the anterior belly of digastric. In approximately half the cases a dominant superficial branch allows for a skin only paddle. Due to the vessel diameter, free tissue transfer is predictable.Venous anatomy is variable and care needs to be taken when raising this flap. The skeletonised version of the perforator flap is largely devoid of nodal yield and on oncological review a 16.3% recurrence rate is equivalent to current standard treatment.

Innovative approaches to teaching vascular access to nursing students in the COVID-19 era.

For the student nurse, peripheral venous cannulation is one of the most stressful skills to be learned. Although some healthcare employers/establishments offer courses on vascular access and infusion nursing as part of their onboarding programs, ultimately educational institutions should share the responsibility to ensure that graduating nurses can provide safe infusion therapies. An innovative vascular access and infusion nursing (VAIN) curriculum was created and mapped onto the entry to practice undergraduate nursing program at McGill University in Montréal, Québec, Canada. This presented an opportunity to implement new teaching approaches. Students experienced multiple new teaching approaches including multimedia and experiential learning and live simulation to ensure acquisition of knowledge and psychomotor skills. The teaching approaches had to be rapidly modified with the advent of the COVID-19 pandemic. The VAIN curriculum emphasizes simulation and directed practice, seeking to increase competence, confidence, and knowledge. The pandemic underscored the need for flexibility and creativity in content delivery.

Evaluation of an Intravitreal Rho-Associated Kinase Inhibitor Depot Formulation in a Rat Model of Diabetic Retinopathy.

Rho-associated kinase (ROCK) activation was shown to contribute to microvascular closure, retinal hypoxia, and to retinal pigment epithelium (RPE) barrier disruption in a rat model of diabetic retinopathy. Fasudil, a clinically approved ROCK inhibitor, improved retinal perfusion and reduced edema in this model, indicating that ROCK inhibition could be a promising new therapeutic approach for the treatment of diabetic retinopathy. However, due to its short intravitreal half-life, fasudil is not suitable for long-term treatment. In this study, we evaluated a very potent ROCK1/2 inhibitor (BIRKI) in a depot formulation administered as a single intravitreal injection providing a slow release for at least four weeks. Following BIRKI intravitreal injection in old Goto-Kakizaki (GK) type 2 diabetic rats, we observed a significant reduction in ROCK1 activity in the retinal pigment epithelium/choroid complex after 8 days and relocation of ROCK1 to the cytoplasm and nucleus in retinal pigment epithelium cells after 28 days. The chronic ROCK inhibition by the BIRKI depot formulation restored retinal pigment epithelial cell morphology and distribution, favored retinal capillaries dilation, and reduced hypoxia and inner blood barrier leakage observed in the diabetic retina. No functional or morphological negative effects were observed, indicating suitable tolerability of BIRKI after intravitreous injection. In conclusion, our data suggest that sustained ROCK inhibition, provided by BIRKI slow-release formulation, could be a valuable treatment option for diabetic retinopathy, especially with regard to the improvement of retinal vascular infusion and protection of the outer retinal barrier.

Genesis of Antibiotic Resistance LXXII: Turbulence Modeling (TM) of Simplified Severe Sepsis Protocol‐2 (SSSP‐2), NCT01663701: Mechanism(s) of Fluid Volume Overload/endotoxemia Induced Thrombocytopenia / Thrombotic Cascade Augment vasoplegia to elicit Leucocyte(s)‐Platelet(s)‐Erythrocyte(s) aggregates (LPE) rescind starling forces

Here we present a plausible schema for fluid resuscitation induced fluid volume overload altering net filtration pressure (NFP) and the onset of comatose. NCT01663701 (PMID: 28973227) noted that the median volume of iv fluid administered between presentation at ED (Emergency department) (Zero hours) (PMID: 20035633) and 6 hours in the sepsis cohort was 3.5 L. The mean volume administered during a similar time interval in prior sepsis ERP trials were 5.0 L (PMID: 11794169, Rivers et.al.,); 20mls/kg iv 0.9% saline with 5% HAS, FEAST, ISRCTN69856593- PMID: 21615299, Maitland et.al.,); Refer Table 1, list of randomized control EGDT, (PMID: 28460438); 5.059L, PMID: 11794169; ProCESS, NCT00510835. (PMID: 24635773); 4.479L; EGDT, ARISE NCT00975793; (PMID: 25272316); 4.2216 L; ProMISe ISRCTN36307479, (PMID: 25776532) (Table 4, Crit Care. 2016; 20: 160. (PMID: 27364620; PMID: 27756870). In essence, fluid overload induced volume expansion is implicit of a pattern of decline in blood flow velocity leading to hypoxia plausibly dysoxia ultimately to anoxia and/or oxygen debt augment platelet activation - aggregation forming LPE occluding thoroughfare capillary bed at the arterial end educe NFP < 10 mmHg impairing filtration, in turn, CCP⇨ vascular shunt. Experimental evidence suggests that the thrombocytopenia in sepsis is initiated by acute and/or chronic viral infection, Rx-immunosuppression, antibiotic therapy, vascular infusion of fluids, which in turn cause an increase in platelet activation, DIC, hemophagocytic lymphohistiocytosis, IgG associated platelets (PAIgG), in a pathogen-associated molecular pattern (PAMPs), subsequent sequestration with leucocytes in neutrophils extracellular traps (NETs) dependent of damage-associated molecular patterns (DAMPs) form a patient-specific LPE occluding the blood flow into the capillary bed (PMID: 31315248; PMID: 29053592). Based on the aforesaid, pathogenesis, we suggest that prior to the admission to the ER, bacteremia with parasitic infection may have caused an increased in LPE formation and sequestration on the damaged glycocalyx impeding the blood flow in turn perfusion (hypovolemia). Our interpretation is that the volume overload exacerbates reperfusion injury of hypoperfused tissues leading to a remote organ injury consequent multiple organ failure due to hypoxia-dysoxia-anoxia cascade fostering an anaerobic/microaerophilic G- pathogens to colonize at an increased rate in vivo. Thus, the impairment of vasomotion by endotoxemia-vasoplegia in the thoroughfare capillary bed is outflanking our TM efforts of defining the mechanisms leading to the increased mortality rate in NCT01663701 (PMID:29332515; PMID:32019600). Taken together we suggest that the mechanism for induction of comatose requires a minimal time constraint (max 30min) in the following sequence: endotoxemia ⇨ vasoplegia ≠⇨ hemostasis≠⇨ homeostasis ≠⇨ NFP <10mmHg ⇔ CCP⇔ GCS scale 3⇔Hypnotic Trans⬅ exception of Lazarus phenomenon ➡ Clinical End Point (mortality).

Vascular infusion with concurrent vascular rinsing on color, tenderness, and lipid oxidation of hog meat

Market hogs were conventionally chilled (CN, n = 12) or Rinse & Chill® processed (RC, n = 13, MPSC Inc.). Muscles (Longissimus lumborum, LL; picnic shoulder, PS) were processed (chops, ground), packaged, and displayed or stored in the dark. Color, pH, moisture fat free (MFF), expressible moisture (EM), oxygen consumption, Warner-Bratzler shear (WBS), total pigment, TBARS, and hexanal content were determined. RC generally resulted in a lower pH during the first 4 h compared to CN. RC compared to CN had lower fat, but were not different in moisture fat free, expressible moisture, and total pigments. RC did not affect cooler shrink, cook loss and WBS force. RC PS was redder than RC LM. RC had greater deoxymyoglobin than CN on 7 d display. RC chops (LL) were lighter and had less deoxymyoglobin compared to CN. RC ground pork had greater oxygen consumption, lower TBARS and hexanal values compared to CN. RC has the potential to improve color and reduce lipid oxidation.

Time to rethink vascular access in patients with breast cancer.

Breast cancer management is a rapidly evolving field. Diagnosis and treatment options have changed dramatically over the years, as have options for vascular access devices used to administer therapies. We now need to critically rethink vascular access device options for our breast cancer patients. Breast cancer (BC) is the most commonly diagnosed cancer among Canadian women. Although BC incidence continues to rise, the overall mortality rate in Canada is the lowest it has been for 70 years. The five-year net survival is 87%, and 83% of women are alive at 10 years. New oral therapies, shorter dose-dense treatments, and decreased use of anthracycline-base regimens are reducing the need for central venous access devices during acute treatment phases. However, these survivors go on to develop other health issues requiring routine venipuncture and insertion of vascular access devices. Breast cancer-related lymphedema (BCRL) is a chronic complication that has no cure and no proven prevention strategies. Approximately 21% of breast cancer survivors are at risk of developing BCRL. Of those patients who do develop BCRL, 70% do so within two years of surgery, 90% within three years, and another one percent per year thereafter. The literature supports axillary lymph node dissection, mastectomy, administration of chemotherapy or radiotherapy, and obesity, as risk factors for the development of BCRL. However, 40% of patients who develop BCRL have no identifiable risk factors. Broader risk reduction strategies developed are not evidence based, the most commonly cited being avoidance of needle sticks. Large cohort studies have found no significant association between blood draws and intravenous infusion in the surgical arm with the development of BCRL. Recommendations that effectively eliminate vascular access on the surgical side for the patient's entire lifetime are neither necessary nor realistic. Vascular access specialists can provide leadership by developing standardized, evidence-informed recommendations for safe vascular access and infusion practices for this patient population.

Ultrasound shear wave elastography for measuring intracompartmental pressure of compartment syndrome using a turkey hind limb model

Diagnosis and treatment of acute compartment syndrome are quite challenging. It is well known that compartment pressure is an important factor for diagnosing fasciotomy. However, the current technology to measure the pressure using a needle-catheter is invasive and painful. Recently ultrasound elastography has been used to measure soft tissue elasticity based on shear wave propagation speed. Because the muscle’s elasticity is affected by the pressure within the compartment, ultrasound elastography might be a possible tool for the compartment pressure evaluation. Ultrasound shear wave elastography and pressure were simultaneously measured using a clinical ultrasound system and clinically used catheter in a turkey anterior-lateral and anterior-deep compartment under elevated pressures of baseline, 10, 20, 30, 40, and 50 mmHg using vascular infusion technique. Shear wave propagation speed increased linearly in proportion to the increase in intra-compartmental pressure. Strong correlation was observed between measured pressure and mean shear wave speed in each compartment (anterior-lateral compartment, mean R2 = 0.929, P < 0.001; anterior-deep compartment, mean R2 = 0.97, P < 0.001). Compared with anterolateral compartment pressure, anterior-deep compartment pressure was the same at the baseline; however, it was significantly higher at intended anterolateral compartment pressures of 20 and 30 mmHg (P = 0.008, P = 0.016). By using ultrasound shear wave elastography, the compartment pressure can be accurately measured. This noninvasive technology can potentially help surgeons for the early detection, monitoring, and prognosis of intra-compartmental pressure.

NIVAS 2019: facing the future in vascular access and infusion therapy.

The 7th National Infusion and Vascular Access Society (NIVAS) conference was held in Manchester, 12-13 June 2019.

Vascular Delivery of Allogeneic MuStem Cells in Dystrophic Dogs Requires Only Short-Term Immunosuppression to Avoid Host Immunity and Generate Clinical/Tissue Benefits

Growing demonstrations of regenerative potential for some stem cells led recently to promising therapeutic proposals for neuromuscular diseases. We have shown that allogeneic MuStem cell transplantation into Golden Retriever muscular dystrophy (GRMD) dogs under continuous immunosuppression (IS) leads to persistent clinical stabilization and muscle repair. However, long-term IS in medical practice is associated with adverse effects raising safety concerns. Here, we investigate whether the IS removal or its restriction to the transplantation period could be considered. Dogs aged 4–5 months old received vascular infusions of allogeneic MuStem cells without IS (GRMDMU/no-IS) or under transient IS (GRMDMU/tr-IS). At 5 months post-infusion, persisting clinical status improvement of the GRMDMU/tr-IS dogs was observed while GRMDMU/no-IS dogs exhibited no benefit. Histologically, only 9-month-old GRMDMU/tr-IS dogs showed an increased muscle regenerative activity. A mixed cell reaction with the host peripheral blood mononucleated cells (PBMCs) and corresponding donor cells revealed undetectable to weak lymphocyte proliferation in GRMDMU/tr-IS dogs compared with a significant proliferation in GRMDMU/no-IS dogs. Importantly, any dog group showed neither cellular nor humoral anti-dystrophin responses. Our results show that transient IS is necessary and sufficient to sustain allogeneic MuStem cell transplantation benefits and prevent host immunity. These findings provide useful critical insight to designing therapeutic strategies.

Infection Control Measures for Patient with Central Line: Nurses' Performance

Background: Central venous catheters (CVCs) are vascular infusion tools utilized for studying hemodynamic variables, dialysis, administration of medication, and nutrition. Catheter related blood stream infection (CRBSI) is a complication of central venous catheter (CVC) use. Central venous catheter-related infection (CVC-RI) is considered a common cause of increased morbidity, mortality, and medical care costs in intensive care units (ICUs). Aim of the study: to assess nurses’ performance regarding infection control measures for patient with central line in critical care unit. Research design: A descriptive exploratory design was utilized. Subjects: Purposive sample of critical care nurses working in the ICU, at El-Fayoum University Hospital, 40 nurses from both genders, with different ages, educational levels and years of experience were selected for this study. Tool: Data were obtained through three main tools; Nurses' Self-administered questionnaire, Nurses' observational checklist and Nurses' attitudes questionnaire tool. Results: this study revealed that about more than two thirds of studied nurses had unsatisfactory knowledge and practice regarding infection control measures related to central line. Also, about (77.5%) of them had negative attitude regarding infection control measures for patient with central line. There were statistically significance correlation between nurses' level of knowledge, practice and their attitude .there were statistical significant relations between nurses' performance and their socio-demographic characteristics as regards age, education and experience Conclusion: Nurses had unsatisfactory level of knowledge, practice and negative attitude regarding infection control measures related to central line. Knowledge, practice &attitude were found to differ significantly in relation to socio-demographic data. Recommendation: Designing nurses’ infection control program to improve their knowledge and practice regarding infection control measures related to central line. The study should be replicated on large sample & in different hospitals setting in order to generalize the results.

The impact of short-chain fatty acids on GLP-1 and PYY secretion from the isolated perfused rat colon.

The colonic epithelium harbors a large number of endocrine cells, but little is known about the endocrine functions of the colon. However, the high density of glucagon like peptide-1 (GLP-1)- and peptide-YY (PYY)-secreting L cells is of great interest because of the potential antidiabetic and antiobesity effects of GLP-1 and PYY. Short-chain fatty acids (SCFAs) produced by local bacterial fermentation are suggested to activate the colonic free fatty acid receptors FFAR2 (GPR43) and FFAR3 (GPR41), stimulating the colonic L cells. We used the isolated perfused rat colon as a model of colonic endocrine secretion and studied the effects of the predominant SCFAs formed: acetate, propionate, and butyrate. We show that luminal and especially vascular infusion of acetate and butyrate significantly increases colonic GLP-1 secretion, and to a minor extent also PYY secretion, but only after enhancement of intracellular cAMP. Propionate neither affected GLP-1 nor PYY secretion whether administered luminally or vascularly. A FFAR2- and FFAR3-specific agonist [( S)-2-(4-chlorophenyl)-3,3-dimethyl- N-(5-phenylthiazol-2-yl)butamide (CFMB)/ AR420626 ] had no effect on colonic GLP-1 output, and a FFAR3 antagonist ( AR399519 ) did not decrease the SCFA-induced GLP-1 response. However, the voltage-gated Ca2+-channel blocker nifedipine, the KATP-channel opener diazoxide, and the ATP synthesis inhibitor 2,4-dinitrophenol completely abolished the responses. FFAR2 receptor studies confirmed low-potent partial agonism of acetate, propionate, and butyrate, compared with CFMB, which is a full agonist with ~750-fold higher potency than the SCFAs. In conclusion, SCFAs may increase colonic GLP-1/PYY secretion, but FFAR2/FFAR3 do not seem to be involved. Rather, SCFAs are metabolized and appear to function as a colonocyte energy source. NEW & NOTEWORTHY By the use of in situ isolated perfused rat colon we show that short-chain fatty acids (SCFAs) primarily are used as a colonocyte energy source in the rat, subsequently triggering glucagon like peptide-1 (GLP-1) secretion independent of the free fatty acid receptors FFAR2 and FFAR3. Opposite many previous studies on SCFAs and FFAR2/FFAR3 and GLP-1 secretion, this experimental model allows investigation of the physiological interactions between luminal nutrients and secretion from cells whose function depend critically on their blood supply as well as nerve and paracrine interactions.

Broadening Infusion Specialization as an Adjunct to Organizational Sustainability

As changes in reimbursement structures create a stringent focus on the prevention of infection and other infusion-related complications that predispose to infection, it becomes important to examine the impact of vascular access and infusion specialty practices and procedures on overall organization sustainability and to implement strategies for disseminating infusion expertise to a broader contingent of nurses. This article discusses infusion nursing practice as it impacts the organization as a whole and details a performance improvement initiative for implementing a novel peripherally inserted central catheter tip determination technology that encompasses many of the goals of the industry standards.

Alteration of hepatic structure and oxidative stress induced by intravenous nanoceria

Beyond the traditional use of ceria as an abrasive, the scope of nanoceria applications now extends into fuel cell manufacturing, diesel fuel additives, and for therapeutic intervention as a putative antioxidant. However, the biological effects of nanoceria exposure have yet to be fully defined, which gave us the impetus to examine its systemic biodistribution and biological responses. An extensively characterized nanoceria (5nm) dispersion was vascularly infused into rats, which were terminated 1h, 20h or 30days later. Light and electron microscopic tissue characterization was conducted and hepatic oxidative stress parameters determined. We observed acute ceria nanoparticle sequestration by Kupffer cells with subsequent bioretention in parenchymal cells as well. The internalized ceria nanoparticles appeared as spherical agglomerates of varying dimension without specific organelle penetration. In hepatocytes, the agglomerated nanoceria frequently localized to the plasma membrane facing bile canaliculi. Hepatic stellate cells also sequestered nanoceria. Within the sinusoids, sustained nanoceria bioretention was associated with granuloma formations comprised of Kupffer cells and intermingling CD3+ T cells. A statistically significant elevation of serum aspartate aminotransferase (AST) level was seen at 1 and 20h, but subsided by 30days after ceria administration. Further, elevated apoptosis was observed on day 30. These findings, together with increased hepatic protein carbonyl levels on day 30, indicate ceria-induced hepatic injury and oxidative stress, respectively. Such observations suggest a single vascular infusion of nanoceria can lead to persistent hepatic retention of particles with possible implications for occupational and therapeutic exposures.

Localized Acid Instillation by a Wedged-Catheter Method Reveals a Role for Vascular Gap Junctions in Spatial Expansion of Acid Injury

Acid aspiration is a major cause of acute lung injury. However, the mechanisms that underlie this spatial expansion of the injury remain undefined. In current animal models of acid injury, intratracheal acid instillation replicates the lung injury. However intratracheal instillation causes a global effect, precluding studies of how the injury spreads. Here, we report an airway catheter-based method for localized acid delivery in the isolated blood-perfused rat lung. We co-instilled hydrochloric acid with evans blue through the catheter into one lung and determined blood-free extravascular lung water in tissue samples from regions that either received, or did not receive the instilled acid. Tissue samples from the noncatheterized contralateral lung were used as controls. Lung water increased both in the regions that received acid, as well as in adjacent regions that did not. Pretreating the lung with vascular infusions of the gap junctional blocker, glycerrhetinic acid, blunted the acid-induced lung water increase at the adjacent regions. These findings indicate that endothelial gap junction communication causes spread of lung injury from regions that were directly acid injured, to adjacent sites that did not directly receive acid. Our new method for establishing localized acid injury provides evidence for a novel role for vascular gap junctions in the spatial expansion of acid injury.

Relaxation of hyperpolarized 129Xe in a deflating polymer bag

In magnetic resonance imaging with hyperpolarized (HP) noble gases, data is often acquired during prolonged gas delivery from a storage reservoir. However, little is known about the extent to which relaxation within the reservoir will limit the useful acquisition time. For quantitative characterization, 129Xe relaxation was studied in a bag made of polyvinyl fluoride (Tedlar). Particular emphasis was on wall relaxation, as this mechanism is expected to dominate. The HP 129Xe magnetization dynamics in the deflating bag were accurately described by a model assuming dissolution of Xe in the polymer matrix and dipolar relaxation with neighboring nuclear spins. In particular, the wall relaxation rate changed linearly with the surface-to-volume ratio and exhibited a relaxivity of κ = 0.392 ± 0.008 cm/h, which is in reasonable agreement with κ = 0.331 ± 0.051 cm/h measured in a static Tedlar bag. Estimates for the bulk gas-phase 129Xe relaxation yielded T 1 bulk = 2.55 ± 0.22 h , which is dominated by intrinsic Xe–Xe relaxation, with small additional contributions from magnetic field inhomogeneities and oxygen-induced relaxation. Calculations based on these findings indicate that relaxation may limit HP 129Xe experiments when slow gas delivery rates are employed as, for example, in mouse imaging or vascular infusion experiments.

Feedback To The Field: An Assessment Of Sternal Intraosseous (io) Infusion

Intraosseous vascular infusion (IO) is a recognized alternative to peripheral intravenous infusion when access is inadequate. The sternum and proximal tibia are the preferred sites. A review of 98 cases at autopsy revealed successful sternal IO placement in 78 cases (80%). Assuming a worst case scenario for placement (pin mark and no tip in bone [17 cases] and tip present and not in the sternum [3 cases]), attempts were unsuccessful in 20 cases (20%). We draw no specific conclusions regarding sternal IO use, but hope that personnel placing these devices and those providing medical training can use the information.

Vasoactivity of hydrogen sulfide in normoxic and anoxic turtles (Trachemys scripta)

Systemic vascular resistance (R(sys)) of freshwater turtles increases substantially during anoxia, but the underlying mechanisms are not fully understood. We investigated whether hydrogen sulfide (H(2)S), an endogenously produced metabolite believed to be an O(2) sensor/transducer of vasomotor tone, contributes to the increased R(sys) of anoxic red-eared slider turtles (Trachemys scripta). Vascular infusion of the H(2)S donor NaHS in anesthetized turtles at 21 degrees C and fully recovered normoxic turtles at 5 degrees C and 21 degrees C revealed H(2)S to be a potent vasoconstrictor of the systemic circulation. Likewise, wire myography of isolated turtle mesenteric and pulmonary arteries demonstrated H(2)S to mediate an anoxia-induced constriction. Intriguingly, however, NaHS did not exert vasoconstrictory effects during anoxia (6 h at 21 degrees C; 14 days at 5 degrees C) when plasma H(2)S concentration, estimated from the colorimetric measurement of plasma acid-labile sulfide concentration, likely increased by approximately 3- and 4-fold during anoxia at 21 degrees C, and 5 degrees C, respectively. Yet, blockade of endogenous H(2)S production by DL-propargylglycine or hydroxylamine (0.44 mmol/kg) partially reversed the decreased systemic conductance (G(sys)) exhibited by 5 degrees C anoxic turtles. These findings suggest that the signal transduction pathway of H(2)S-mediated vasoactivity is either maximally activated in the systemic circulation of anoxic turtles and/or that it is oxygen dependent.

SH13 A CENTURY OF POLAR MEDICINE

In 1909, when the heroic period of Polar Exploration was in full swing, parties venturing to the Polar Regions particularly to the Antarctic were totally isolated. Medical knowledge and resources compared to now were basic to say the least. Over and above this communication with the outside world was virtually non‐existent but for the Morse code which was not always entirely reliable.In 1909, when Mawson journeyed to the South Magnetic Pole knowledge of vitamins, antibiotics and vascular infusion techniques, all now commonplace, were in the future. All has now changed and the sheer immensity of the changes in medical knowledge and in communication is the subject of this presentation. The Australian National Antarctic Research Expeditions which evolved from Mawson's pioneering efforts have been at the forefront of these changes. Expeditioners now are safe in the knowledge that help is readily at hand both at their bases and in Australia.

Low-End Videoconferencing for Vascular Access Device Site Assessment in Homecare

Vascular access devices (VAD) represent high technology and are used frequently in infant, pediatric, adult, and geriatric populations for vascular infusion of chemotherapy, immunotherapy, blood products, biologic response modifiers, nutrition support, analgesics, ionotropics, antibiotics, and other medications, as well as for extraction of pleural fluid from patients with chronic effusions and for treatment with dialysis. Increasingly, these devices are migrating to the home setting as they are used in chronic care and as insurance requirements reduce access to prolonged hospital stays.Surveillance of infections in high risk patients such as those with cancer, cardiac conditions, or post-trauma convalescence is essential to avoid adverse events and to offer early treatment. VAD site and blood stream infections are common VAD complications, occurring in up to 50% of home care patients, usually during days 4–25 after hospital discharge. Our literature search for reports of remote home monitoring for support of VAD patients and their caregivers found none.The use of videoconferencing technology to assess VAD sites in the post-discharge environment would significantly enhance patient safety, facilitate continuity of care, and meet the Communicable Disease Center's stated need for the development of surveillance systems to monitor infections in home care settings. Low-cost Internet- or telephone-based videoconferencing technology that could be deployed easily and used during risk periods would be highly beneficial to patients and increase the cost-effective use of homecare nursing personnel.We report criteria-based protocols for remote assessment of VAD status, for monitoring VAD care procedures employed in the home, and for conducting VAD-care teaching of patients and their caregivers. In addition, we report an initial evaluation of the ability to assess VAD status using low-end videoconferencing technologies.