Cannula Size Research Articles

Flow rates through intravenous access devices: an in vitro study

Study objectiveFluid administration using intravenous (IV) access devices is required in many settings. There are a lack of quantitative data comparing traditional cannulas and modern access devices. We aimed to investigate flow rates through modern intravenous access devices using an in vitro system. DesignThis is an experimental study. Setting and measurementsRates of flow of intravenous fluids (crystalloid and colloid) were measured through various access devices using a uroflowmeter. Standardized conditions and repeat measurements ensured validity. Fluid was administered with or without the addition of a pressure bag and needle-free valve. Main resultsIncreasing the size of cannulas improved flow. Fourteen-gauge cannulas had significantly higher mean flow rates compared to 14G central venous lines in all conditions (136% higher with no pressure bag/valve; 95% CI, +130% to +152%; P < .001). Both the emergency infusion device and rapid infusion catheter produced significantly increased mean flows compared to a 14G cannula (12% higher for emergency infusion catheter; 95% CI, +7% to +15%; P = .008, and 15% higher for rapid infusion catheter; 95% CI, +12% to +21%; P = .004). The needle-free valve significantly impaired flow on 16G and wider IV access devices (36% lower with no pressure bag using 14G cannula; 95% CI, −29% to −46%; P = .003), but flow reductions in narrower IV access were insignificant. Pressure bags significantly improved flow in all devices, in all combinations. ConclusionsFlow rates in IV devices can be maximized by pressure bag use and removal of needle-free valves. The rapid infusion catheter and emergency infusion catheter allow some increase in flow over a 14G cannula. Familiarity with varying flow rates across IV access devices could better inform clinical decisions.

Trans-hepatic cannulation: a novel approach for placement of a pediatric percutaneous ventricular assist device.

Pediatric ventricular assist device (VAD) use is increasing. The TandemHeart PTVA system is a percutaneous VAD used in adults. Pediatric use is limited by cannula size. Trans-hepatic left atrial (LA) cannulation offers the possibility of shorter, larger-diameter cannulae, but specific requirements for cannula size and flow characteristics need to be developed. We evaluated the feasibility of trans-hepatic cannulation based on patient measurements and bench-top modeling. Two hundred patients admitted to the University of Michigan Pediatric CICU were evaluated. Patients over 14 years and dextrocardiac patients were excluded. The distance from the skin between the 10th and 11th ribs at the mid-axillary line to the left-heart border was measured on x-ray. LA size was measured on echocardiogram. From these measurements, prototype cannulae were fabricated. Benchtop testing of developed cannulae was performed with a pump speed of 8500 RPM and fluid viscosity of 4.0 cP at physiologic atrial and arterial pressures. Inlet pressure and deliverable flows were measured. The proposed design delivered sufficient flow with negative pressures low enough to avoid hemolysis. Trans-hepatic LA cannulation for percutaneous VAD placement is feasible. The shorter distance to the LA and larger hepatic vein size allows design of pediatric-appropriate cannulae with adequate flow rates.

The Current State of Fat Grafting: A Review of Harvesting, Processing, and Injection Techniques.

Interest in and acceptance of autologous fat grafting for use in contour abnormalities, breast reconstruction, and cosmetic procedures have increased. However, there are many procedural variations that alter the effectiveness of the procedure and may account for the unpredictable resorption rates observed. The authors highlighted studies investigating the effects of harvesting procedures, processing techniques, and reinjection methods on the survival of fat grafts. This review focused on the impact different techniques have on outcomes observed in the following: in vitro analyses, in vivo animal experiments, and human studies. This systemic review revealed the current state of the literature. There was no significant difference in the outcomes of grafted fat obtained from different donor sites, different donor-site preparations, harvest technique, fat harvesting cannula size, or centrifugation speed, when tumescent solution was used. Gauze rolling was found to enhance the volume of grafted fat, and no significant difference in retention was observed following centrifugation, filtration, or sedimentation in animal experiments. In contrast, clinical studies in patients found more favorable outcomes with fat processed by centrifugation compared with sedimentation. In addition, higher retention was observed with slower reinjection speed and when introduced into less mobile areas. There has been a substantial increase in research interest to identify methodologies for optimizing fat graft survival. Despite some differences in harvest and implantation technique in the laboratory, these findings have not translated into a universal protocol for fat grafting. Therefore, additional human studies are necessary to aid in the development of a universal protocol for clinical practice.

Impairment of Venous Drainage on Extracorporeal Membrane Oxygenation Secondary to Air Trapping in Acute Asphyxial Asthma

The inability to adequately support a patient on extracorporeal membrane oxygenation (ECMO) due to impaired drainage is not an uncommon occurrence during support. Typically, the causes include hypovolemia, kinks in the circuit, cannula malposition, or inadequate cannula size. In this report we present an uncommon etiology of this problem. A 3-year-old female presented to our hospital in status asthmaticus and pulseless electrical activity (PEA). This was a result of dynamic hyperinflation of the lungs causing physical obstruction of venous return to the heart. Upon initiating venoarterial (VA) ECMO, we experienced inadequate drainage that did not improve despite multiple interventions. This resolved with the addition of an inhaled anesthetic gas to treat this patient’s severe bronchospasm. This case illustrates the importance of considering a patient’s physiology or disease state and how that may affect the mechanics of ECMO support.

RR8. Outcome of Rectus Femoris Muscle Flaps for Femoral Arterial Graft Complications

Objectives: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a salvage therapy in patients with severe cardiopulmonary failure. Because large cannulas (16-24F) are necessary to achieve adequate oxygenation, the femoral artery is the most common access site. Unfortunately, femoral cannulation has been associated with limb complications (10%-70%), including ischemia, limb loss, and compartment syndrome. This study aimed to evaluate these complications and management related to limb salvage. Methods: A retrospective review was conducted of 91 consecutive patients requiring VAECMO via femoral cannulation from July 2010 until January 2015. At the time of cannulation, most patients had percutaneous placement of distal arterial perfusion catheters (DPC). After cannulation, all patients were monitored by a near-infrared spectroscopy (NIRS) algorithm and hourly lower extremity examination by trained cardiac intensive care nursing staff, with immediate notification of any change from baseline. ECMO decannulation involved a femoral cutdown with arteriotomy closure by either primary repair or patch angioplasty with bovine pericardium. Study end points included limb ischemia, compartment syndrome requiring fasciotomies, and limb loss. Results: Ninety-one patients were supported with VA-ECMO with femoral arterial cannula sizes from 1624F. Mean length of time on ECMO was 9.1 days (range, 1-40 days). Percutaneous DPC was placed immediately in 62 of 91 patients, with no subsequent ischemia. Of the 29 patients without initial DPC placement, 12 (41.4%; 13.2% of all VA ECMO) developed acute ischemia. Two patients subsequently had DPC placement only, 5 had DPC placement and fasciotomies, 4 had fasciotomies only, and 1 patient required amputation after presenting with acute ischemia after cannulation at another hospital. After DPC placement, all patients had resolution of limb ischemia. The remaining 17 patients without DPC placement experienced no vascular compromise. Overall survival in our VAECMO population was 64%; in patients with limb complications, mortality was 75%. Conclusions: Historically, femoral VA-ECMO has been associated with significant limb ischemic complications. A systematic protocol including NIRS monitoring, trained intensive care nursing staff, DPC placement, decannulation with primary repair of arteriotomies or patch angioplasty can decrease rates of limb ischemia leading to limb loss.

Percutaneous cannulation for extracorporeal membrane oxygenation by intensivists: a retrospective single-institution case series.

Extracorporeal membrane oxygenation provides support for patients with severe acute cardiopulmonary failure, allowing the application of lung or myocardial rest in anticipation of organ recovery, or as a bridge to long-term support. Advances in technology have improved the safety and ease of application of extracorporeal membrane oxygenation. Percutaneous cannulation is one of these advances and is now preferred over surgical cannulation in most cases. Percutaneous cannulation is increasingly performed by intensivists, cardiologists, interventional radiologists, and related specialties. The objective of this study is to review the experience of percutaneous cannulation by intensivists at a single institution. A retrospective review of 100 subjects undergoing percutaneous cannulation for extracorporeal membrane oxygenation. Adult ICUs and PICUs at a tertiary academic medical institution. Critically ill neonatal, pediatric, and adult subjects with severe respiratory and/or cardiac failure undergoing percutaneous cannulation for extracorporeal membrane oxygenation. Modes of support included venoarterial, venovenous, venovenoarterial, and arteriovenous. Percutaneous extracorporeal membrane oxygenation. Case reports submitted to the Extracorporeal Life Support Organization and hospital records of the subjects were retrospectively reviewed. Subject demographics, type of support, cannulation configuration, types of cannulas, use of imaging modalities, and complications were recorded and summarized. One hundred ninety cannulations with cannula sizes from size 12 to 31F were performed by four intensivists in 100 subjects. Twenty-three were arterial (12-16F) and 167 were venous (12-31F). Preinsertion ultrasound was performed in 93 subjects (93%), fluoroscopic guidance in 79 subjects (85% of nonarteriovenous subjects), and ultrasound-guided insertion was performed in 65 subjects (65%). Two major complications occurred, each associated with mortality. Cannulation was successful in all other subjects (98% of subjects and 99% of cannulations). There were no cases of cannula-related bloodstream infection. Percutaneous cannulation for extracorporeal membrane oxygenation by intensivists can be performed with a high rate of success and a low rate of complications when accompanied by imaging support.

Factors influencing delivered mean airway pressure during nasal CPAP with the RAM cannula.

To measure mean airway pressure (MAP) delivered through the RAM Cannula® when used with a ventilator in CPAP mode as a function of percent nares occlusion in a simulated nasal interface/test lung model and to compare the results to MAPs using a nasal continuous positive airway pressure (NCPAP) interface with nares fully occluded. An artificial airway model was connected to a spontaneous breathing lung model in which MAP was measured at set NCPAP levels between 4 and 8 cmH2 O provided by a Dräger Evita XL® ventilator and delivered through three sizes of RAM cannulae. Measurements were performed with varying leakage at the nasal interface by decreasing occlusion from 100% to 29%, half-way prong insertion, and simulated mouth leakage. Comparison measurements were made using the Dräger BabyFlow® NCPAP interface with a full nasal seal. With simulated mouth closed, the Dräger interface delivered MAPs within 0.5 cmH2 O of set CPAP levels. For the RAM cannula, with 60-80% nares occlusion, overall delivered MAPs were 60 ± 17% less than set CPAP levels (P < 0.001). Further, MAP decreased progressively with decreasing percent nares occlusion. The simulated open mouth condition resulted in significantly lower MAPs to <1.7 cmH2 O. The one-half prong insertion depth condition, with closed mouth, yielded MAPs approximately 35 ± 9% less than full insertion pressures (P < 0.001). In our bench tests, the RAM interface connected to a ventilator in NCPAP mode failed to deliver set CPAP levels when applied using the manufacturer recommended 60-80% nares occlusion, even with closed mouth and full nasal prong insertion conditions.

Vascular air embolism after contrast administration on 64 row multiple detector computed tomography: A prospective analysis.

Background:Vascular air embolism is being progressively reported as a nonfatal event with increase in use of computed tomography (CT) as a diagnostic modality. This study was undertaken to study the frequency and site of vascular air embolism in patients undergoing contrast-enhanced CT (CECT) and analyze CT parameters that influence its prevalence and final outcome.Materials and Methods:This was a prospective study approved by departmental ethics committee. Presence and location of air emboli in 200 patients who underwent CT scan of chest on a 64 detector scanner was recorded. We analyzed the role of various factors that could influence the prevalence of air embolism after injection of contrast in CECT scans. These factors included the amount of contrast injected, rate of flow of injection of contrast, site of injection of contrast, and size of intravenous access line.Results:Iatrogenic vascular air emboli were seen in 14 patients (7% of total). The locations of air emboli were main pulmonary artery in 12 (6% of total), left brachiocephalic vein in 3 (1.5% of total), right atrial appendage in 4 (2% of total), and superior vena cava (SVC) in 1 (0.5%) patient. There was no association between volume of contrast, flow rate, site and size of intravenous access, and presence of air emboli.Conclusion:Radiologists as well as referring physicians should be aware of vascular air embolism, which can occur after contrast injection in patients undergoing CT scan. Age, volume of contrast, flow rate of pressure injector, and site and size of venous cannula do not influence the likelihood or incidence of detection of venous air emboli on CT scans.

The Effect of Vacuum on Venous Drainage: an Experimental Evaluation on Pediatric Venous Cannulas and Tubing Systems

To observe how vacuum assisted venous drainage (VAVD) may influence the flow in a cardiopulmonary bypass circuit with different size of venous lines and cannulas. The experimental circuit was assembled to represent the cardiopulmonary bypass circuit routinely used during cardiac surgery. Wall suction was applied directly, modulated and measured into the venous reservoir. The blood flow was measured with a flow-meter positioned on the venous line. The circuit prime volume was replaced with group O date expired re-suspended red cells and Plasmalyte 148 to a hematocrit of 28% to 30%. In an open circuit with gravity siphon venous drain, angled cannulae drain more than straight ones regardless the amount of suction applied to the venous line (16 Fr straight cannula (S) drains 90 ml/min less than a 16 Fr angled (A) with a siphon gravity). The same flow can be obtained with lower cannula size and higher suction (i.e. 12 A with and -30 mmHg). Tables have been created to list how the flow varies according to the size of the cannulas, the size of the venous tubes, and the amount of suction applied to the system. Vacuum assisted venous drainage allows the use of smaller cannulae and venous lines to maintain a good venous return, which is very useful during minimally invasive approaches. The present study should be considered as a preliminary attempt to create a scientific-based starting point for a uniform the use of VAVD.

PS-376 Non-invasive Ventilation In Neonates: Effect Of Nasal Cannula Size, Insertion Depth And Nares Diameter On Mean Airway Pressure - An In-vitro Study

<h3>Background</h3> Increased neonatal Non-Invasive Ventilation (NIV) use, such as nCPAP and high flow nasal cannula (HFNC) prompted re-evaluation of nasal interface devices – specifically short bi-nasal prongs, and their size and fit relative to the nares. <h3>Objective</h3> To quantify the effect of nasal prong size and insertion depth on generated mean airway pressure (MAP) during NIV. <h3>Design/methods</h3> A Dräger traditional nCPAP interface, three sizes of RAM cannulae (Neotech, Valencia, CA, USA) and two Fisher and Paykel (FP) (Auckland, NZ) HFNC cannulae were tested with 8 simulated nares sizes. A simulated nasal airway was connected to an active lung model set at: Vt 8–10 ml, 60 b/m, Ti 0.35–0.40 s. A Dräger Evita XL ventilator delivered 4,5,6,7 and 8 cmH₂O to the RAM and the Dräger nCPAP cannulae and a FP HFNC system delivered 1–6 L/m flows. MAP was measured for open and closed-mouth conditions. <h3>Results</h3> MAP decreased progressively as the percent nares occlusion (%Occl) decreased. At one-half insertion and closed-mouth conditions, close fitting prongs with high% Occl yielded MAP’s of one-half of set CPAP levels. Delivered MAP’s were significantly lower during open-mouth condition using either HFNC or CPAP cannulae. MAP increased with both flowrate and%Occl. A rapid rise in pressure was associated with% Occl’s &gt;74%. Complete nares occlusions generated the highest pressures. Simulated closed-mouth produced 12 ± 7 SD higher MAP’s than open-mouth over all%Occl’s at HFNC flows &gt;1 L/m. <h3>Conclusion</h3> RAM ‘CPAP’ does not deliver MAP as effectively as standard nasal prong CPAP. Optimum delivered airway pressure is dependent on appropriate %Occl, insertion depth and NIV settings.

Acute Nasal Reconstruction With Forehead Flap After Dog Bite

Acute Nasal Reconstruction With Forehead Flap After Dog Bite

In-line pressure within a HOTLINE® Fluid Warmer, under various flow conditions.

Roller pump infusion devices are widely used for rapid infusion, and may be combined with separate warming devices. There may be instances however, where the pressures generated by the roller pump may not be compatible with the warming device. We assessed a commonly used roller pump in combination with a HOTLINE® Fluid Warmer, and found that it could generate pressures exceeding the HOTLINE® manufacturers specifications. This was of concern because the HOTLINE® manufacturer guideline states that not for use with pressure devices generating over 300 mmHg. Pressure greater than 300 mmHg may compromise the integrity of the HOTLINE® Fluid Warming Set. The aim of this study was to compare in-line pressure within a HOTLINE® Fluid Warmer at different infusion rates of a roller pump using various sizes of intravenous cannulae. The rapid infusion system comprised a 500 mL-normal saline bag, roller pump type infusion device, HOTLINE® Fluid Warmer (blood and fluid warmer system), and six different sizes of intravenous cannulae. In-line pressure was measured proximal to the HOTLINE® (pre-warmer) and proximal to the cannula (post-warmer), at flow rate of 50-160 mL/min. The in-line pressures increased significantly with increasing flow rate. The pre-warmer pressures exceeded 300 mmHg when the flow rate was ≥120 mL/min with 20-gauge, 48 mm length cannula, 130 with 20-gauge, 25 mm cannula, and 160 mL/min with 18-gauge, 48 mm cannula. However, they were <300 mmHg at any flow rates with 18-gauge, 30 mm cannula and 16-gauge cannulae. The post-warmer pressures exceeded 300 mmHg at the flow rate of 140 mL/min with 20-gauge, 48 mm cannula, and 160 mL/min with 20-gauge, 25 mm cannula, while they were <300 mmHg at any flow rates with 18 and 16-gauge cannulae. The in-line pressure within a HOTLINE® could exceed 300 mmHg, depending on the flow rate and size and length of cannula. It is important to pay attention to the size and length of cannulae and flow rate to keep the maximum in-line pressure<300 mmHg when a roller pump type infusion device is used.

The Impact of Liposuction Cannula Size on Adipocyte Viability

Tambasco, Damiano MD; Arena, Vincenzo MD; Finocchi, Valerio MD; Grussu, Francesca MD; Cervelli, Daniele MD, PhD Author Information

Fluid prescription practices of anesthesiologists managing patients undergoing elective colonoscopy: an observational study.

BackgroundRoutine fluid prescription is common practice amongst anesthesiologists caring for patients undergoing colonoscopy. However there is limited information about routine procedural fluid prescription practices of anesthesiologists in this setting. Routine fluid administration may also have important pharmaco-economic implications for the health care budget. Therefore we performed a prospective observational study assessing the fluid prescription practices of anesthesiologists caring for patients undergoing elective colonoscopy.MethodsWith Institutional Review Board approval, adult patients receiving procedural fluid intervention during elective colonoscopy were included. Data collected: size of intravenous cannula inserted, volumes of fluid administered, adverse events, procedure duration, and pharmaco-economic costs associated with fluid prescription. Anesthesiologists and gastroenterologists were blinded to the study.ResultsWe collected data on 289 patients who received fluid prescription by their attending anesthesiologist. Median patient age: 48 yrs (range 18–83), gender: 174 (60%) female; median duration of procedure: 24 minutes (range 12–48). Cannula size: 181 (63%) patients received a 22G cannula or smaller. Median volume of fluid administered during the colonoscopy was 325 ml (range 0 to 1000 ml). Median duration of the procedure: 25 minutes (range 12 to 48 minutes). Median volume of fluid administered in the post anaesthesia recovery unit: 450 ml (range 0 to 1000 ml). Fifteen patients (5%) became hypotensive during the procedure and two patients (<1%) developed hypotension in the PACU. There was no difference in the median fluid requirements between patients with hypotension and those without. Fluid volumes were strongly associated with increasing cannula diameter (p = 0.0001), however there was no association between fluid volumes administered and vasopressor use, peri-procedural adverse events, or procedure duration. At our institution fluid therapy currently cost about AUD$4.90 per patient: 1 L crystalloid $1.18 and fluid delivery set $3.77 Our institution performs over 9000 endoscopic procedures annually with fluid therapy costing about $45,000/year.ConclusionsRoutine fluid prescription by anesthesiologists managing patients undergoing colonoscopy was ineffective with low actual fluid volumes delivered during the procedure. There was no association between volumes of fluid delivered and procedural hypotension, adverse events, or procedure duration. Anesthesiologists should question the clinical and pharmaco-economic value of routine fluid administration for patients undergoing elective endoscopy.

Enabling speech in ICU patients during mechanical ventilation

Dear Editor, Inability to speak during mechanical ventilation (MV) increases psycho-emotional distress during ICU treatment [1]. Although relevant for all ICU patients, this problem becomes more prominent in patients with a prolonged weaning period. One way to enable speech in tracheotomised patients during the weaning period is to alternate MV with time-limited trials of cuff-deflated spontaneous breathing in combination a speaking valve. However, not all patients tolerate such interruptions of MV [2]. Although not commonly used, MV with deflated cuff in tracheotomised patients may be an alternative approach, and has been provided safely and comfortably in selected groups of non-ICU patients [3]. Its use has been associated with improved swallowing and the possibility to speak [4]. However, in daily clinical ICU practise the use of MV under such conditions is limited by multiple ventilator alarms, as a result of air leakage. Furthermore, optimisation of speech is hampered by loss of airflow during open airway MV. We describe our experiences to improve speech in tracheotomised ICU patients during cuff-deflated MV, in combination with a high flow non-invasive ventilator and a one-way tracheostomy speaking valve. In 2013, 24 patients in our mixed medical-surgical ICU were tracheotomised, using a percutaneous dilatation technique. Five patients were able to wean and speak with progressive periods of spontaneous breathing trials. Five patients were weaned from MV without the ability to speak, one patient died within 2 days after the tracheotomy, and one patient had persistent insufficient air leakage around the cannula, despite reduction in cannula size. Table 1 summarizes the characteristics of the remaining 12 patients. Within 24 h after the tracheotomy procedure air leakage was present after deflation of the cuff. Invasive pressure support ventilation was replaced by a BiPAP mode with a non-invasive ventilator (BiPAP Vision®, Philips, Best, the Netherlands) at equal ventilator settings. A minimum PEEP level of 8 cmH2O was maintained in order to prevent rebreathing of CO2. Furthermore, an increasing level of PEEP has been associated with a prolonged duration and improved quality of speech [5]. In case all expiratory flow passed through the oropharyngeal route, a Passy Muir® speaking valve (Passy Muir Inc., Irvine, USA) was installed in the circuit to enhance speech (Fig. 1). All 12 patients were able to speak in the first day after switching to the BiPAP setting, enabling effective communication with relatives and medical personnel. Quality and duration of speech improved over time. Effective weaning from MV was achieved in all patients by progressive intervals of CPAP. During CPAP the ability to speak was similar to that in the BiPAP mode. Median time from the beginning of speech to the end of MV was 12 ± 6 days. Table 1 Patient characteristics Fig. 1 Ventilator setting; Passy Muir® one-way speaking valve in red circle We conclude that in a selected group of difficult-to-wean tracheotomised ICU patients the ability to speak may effectively be restored by cuff-deflated non-invasive BiPAP ventilation in combination with a one-way speaking valve. We encourage intensive care personnel to develop similar weaning protocols, in an effort to improve well-being of ICU patients.

Distal limb perfusion: Achilles' heel in peripheral venoarterial extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a temporary mechanical circulatory assist method that offers circulatory as well as respiratory support efficiently via peripheral access; however, it is liable to complications. Limb ischemia is one of the notorious complications of ECMO but can be avoided utilizing a proper distal limb perfusion method. A retrospective study of patients undergoing peripheral venoarterial (VA) ECMO for various reasons between June 2010 and December 2012 was performed. All patients were evaluated by our multidisciplinary team for suitability as candidates for ECMO. A peripheral VA-ECMO circuit was implanted via groin: inflow cannula in the femoral vein, an outflow cannula and distal-perfusion cannula, or an introducer sheath in the femoral artery. During the study period, 83 patients underwent various types of ECMO; 45 received peripheral VA-ECMO. Distal limb perfusion was achieved with an introducer sheath (6-8 Fr) in 13 cases and with a distal-perfusion cannula (10-12 Fr) in 32 cases. Nine (20%) patients developed signs of ischemia; five (11.2%) were treated conservatively, while four (8.8%) required surgical intervention. One patient required a below-knee amputation. The incidences of limb ischemia and limb ischemia requiring surgical intervention were significantly higher for the introducer sheath compared with the cannula (30.6 vs. 15.6% and 15.4 vs. 6.25%, respectively). Moreover, the patients supported on ECMO with a distal-perfusion cannula spent a significantly longer time on ECMO compared with the ones in whom an introducer sheath was used (11.9 ± 9.1 vs. 7.7 ± 4.3 days). The mean cannula size was significantly greater than the mean introducer sheath size (11.1 ± 1.3 vs. 7.0 ± 1.1 Fr). Use of a distal-perfusion cannula is a most reliable method of limb perfusion in peripheral VA-ECMO. The cannula can ensure adequate and smooth perfusion of the limb owing to its large caliber, its less turbulent flow, the ability it provides to monitor the flow, and the option to attach a side port.

Donepezil nanosuspension intended for nose to brain targeting: In vitro and in vivo safety evaluation

The present study was to develop donepezil loaded nanosuspension for direct olfactory administration which reaches the brain and determining safety profile in Sprague–Dawley rats. Nanosuspension was prepared by ionic-crosslinking method. The developed nanosuspension was intranasally instilled into the nostrils of rats with the help of cannula (size 18/20) so that drug reached into the brain directly via nose to brain pathway. The nanosuspension had an average size of 150–200nm with a polydispersity index of 0.341. The donepezil concentration was estimated in the brain homogenate using HPLC method. The Cmax showed concentration of donepezil in brain and plasma as 7.2±0.86 and 82.8±5.42ng/ml, respectively, for drug suspension and concentration of donepezil in brain and plasma as 147.54±25.08 and 183.451±13.45ng/ml, respectively, for nanosuspension at same dose of 0.5mg/ml when administered intranasally (p<0.05). The in vivo safety evaluation studies showed that no mortality, hematological changes, body weight variations and toxicity in animals was observed, when nanosuspension was administered in different doses as compared to control group (normal saline). Donepezil loaded chitosan nanosuspension is a potential new delivery system for treatment of Alzheimer's disease, when transported via olfactory nasal pathway to the brain.

Veno-venous extracorporeal CO2 removal for the treatment of severe respiratory acidosis: pathophysiological and technical considerations.

IntroductionWhile non-invasive ventilation aimed at avoiding intubation has become the modality of choice to treat mild to moderate acute respiratory acidosis, many severely acidotic patients (pH <7.20) still need intubation. Extracorporeal veno-venous CO2 removal (ECCO2R) could prove to be an alternative. The present animal study tested in a systematic fashion technical requirements for successful ECCO2R in terms of cannula size, blood and sweep gas flow.MethodsECCO2R with a 0.98 m2 surface oxygenator was performed in six acidotic (pH <7.20) pigs using either a 14.5 French (Fr) or a 19Fr catheter, with sweep gas flow rates of 8 and 16 L/minute, respectively. During each experiment the blood flow was incrementally increased to a maximum of 400 mL/minute (14.5Fr catheter) and 1000 mL/minute (19Fr catheter).ResultsAmelioration of severe respiratory acidosis was only feasible when blood flow rates of 750 to 1000 mL/minute (19Fr catheter) were used. Maximal CO2-elimination was 146.1 ± 22.6 mL/minute, while pH increased from 7.13 ± 0.08 to 7.41 ± 0.07 (blood flow of 1000 mL/minute; sweep gas flow 16 L/minute). Accordingly, a sweep gas flow of 8 L/minute resulted in a maximal CO2-elimination rate of 138.0 ± 16.9 mL/minute. The 14.5Fr catheter allowed a maximum CO2 elimination rate of 77.9 mL/minute, which did not result in the normalization of pH.ConclusionsVeno-venous ECCO2R may serve as a treatment option for severe respiratory acidosis. In this porcine model, ECCO2R was most effective when using blood flow rates ranging between 750 and 1000 mL/minute, while an increase in sweep gas flow from 8 to 16 L/minute had less impact on ECCO2R in this setting.

Abstract 345: Effects of Cannula Size in Venoarterial Extracorporeal Membrane Oxygenation

Background: The degree of circulatory support that patients treated with veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) receive is limited by the size of the arterial cannula. However, the use of ECMO is associated with significant morbidity related to complications of cannulation, including limb ischemia and need for blood transfusion. We investigated the relationship between cannula size and clinical outcomes as well as transfusion needs in patients treated with VA ECMO. Methods: We performed a retrospective review of all patients treated with percutaneous VA ECMO at the University of Chicago Medical Center from January to December 2012. Baseline characteristics, size of arterial cannula, blood transfusions, and outcomes were recorded. Fisher’s exact test was used to compare the association between survivor status and cannula size (15 vs greater than 15 Fr). Association between cannula size and transfusion of packed red blood cells over the first 24 hours of treatment was determined using a quadratic regression model. Results: Percutaneous VA ECMO was initiated in 15 patients. 7 patients were alive at 30 days after ECMO initiation. The use of a smaller cannula was significantly associated with survival (P &lt; 0.01) There was an association between the size of the arterial cannula and blood transfusion needs (P &lt;0.01). Two patients experienced significant hemorrhage related to cannulation. Other major complications included HIT (1) and DIC (1). Limb ischemia was not seen as all patients underwent anterograde cannulation at time of ECMO initiation. Conclusions: Use of smaller arterial cannulae in VA ECMO was associated with increased survival and there was a correlation between cannula size and need for transfusion. Smaller cannulae result in lower flow rates, but also in reduced vascular complications. Further study is warranted to determine the balance between providing circulatory support and reducing complications in patients treated with VA ECMO.

Abstract 74: Sequential Organ Failure Assessment Score at Presentation Predicts Survival in Venoarterial Extracorporeal Membrane Oxygenation

Background: Veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) has been reported to improve survival in patients with cardiogenic shock (CS) or cardiac arrest (CA). However, overall mortality remains high and many patients may not benefit from ECMO. The Sequential Organ Failure Assessment (SOFA) score is an assessment of a patient’s organ function in the setting of shock composed of scores for the respiratory, cardiovascular, hepatic, coagulation, renal, and neurologic systems, graded 0 to 4 based on level of dysfunction. We investigated the role of the SOFA score in predicting survival in CS and CA patients treated with ECMO. Methods: We performed a retrospective review of all patients treated with percutaneous VA ECMO at the University of Chicago Medical Center from January to December 2012. SOFA score at presentation was calculated using available clinical data. Demographics, clinical characteristics, and outcomes of survivors versus non-survivors were compared using fisher’s exact test. An age adjusted logistic regression model was used to calculate the association between SOFA score and survivor status. Results: Percutaneous VA ECMO was initiated in 15 patients. 7 were alive at 30 days after ECMO initiation. Survivors had a significantly lower baseline median SOFA score (9 vs 16, p= 0.03, OR 0.577 ). The only other significant predictors of survival were female sex and smaller cannula size. Major complications included hemorrhage (2), HIT (1) and DIC (1). Limb ischemia was not seen in any patients as all patients underwent anterograde cannulation at the time of ECMO initiation Conclusions: The presenting SOFA score predicts survival in patients with CS or CA who undergo VA ECMO. Calculation of the SOFA score at presentation may help physicians decide which patients may derive benefit from ECMO.