Cannula Flow Research Articles

Left Ventricular Assist Device Flow Pattern Analysis Utilizing a Novel Computational Fluid Dynamics Model: Using Physics and Physiology to Better Define the Pump-Patient Interaction

Introduction Blood flow patterns through the left ventricular assist device (LVAD) and aorta remain incompletely understood. Computational fluid dynamics (CFD) allows for analysis of flow in the cardiovascular system although current LVAD models have failed to fully incorporate the interplay between the pulsatile left ventricle and continuous-flow generated by the LVAD. Hypothesis Flow through the LVAD is dependent on the interaction between device and patient specific factors with suboptimal flow patterns evoking increased risk of LVAD-related complications. CFD can be used to analyze how different pump and patient factors affect flow through the system. Methods CFD simulations were carried out on a patient with a HeartMate II (HMII) (Fig A). Simulations were also done substituting HeartWare HVAD (Fig B), HeartMate 3 (HM3) in continuous mode (Fig C) and HM3 with Artificial Pulse (Fig D). An anatomical model of the patient was reconstructed from CT images. The LVAD flow was calculated separately using a lumped-parameter-model (LPM), which was calibrated to the patient based on the patient-specific ventricular volume change reconstructed from 4 dimensional CT and hemodynamic tracings. The LVADs were implemented in the LPM via published H-Q curves. In order to quantify the flushing effect, virtual contrast agent was released in the ascending aorta and its flushing over the cycles was quantified. Results Under standard operation conditions of the LVADs (9200 RPM for HMII, 5500 RPM for HM3 and 2600 RPM for HVAD), the cardiac outputs were 5.92 L/min, 6.14 L/min and 6.90 L/min, for HMII, HM3 and HVAD, respectively. The velocity of blood flow in the outflow cannula was higher in the HVAD than in the two HeartMate pumps with a cycle average (range) of 0.72 m/s (0.57-0.93 m/s), 0.70 m/s (0.64-0.77 m/s) and 1.61 m/s (1.21-1.92 m/s) for HMII, HM3 and HVAD, respectively. Artificial Pulse increased the peak flow rate to 9.84 L/min for the HM3 but the overall cardiac output was 5.96 L/min, which was similar to the continuous mode (Fig E). Artificial pulse markedly accelerated flushing of the blood from the ascending aorta; after 6 cardiac cycles, 43% of the blood was flushed out from the ascending aorta under the continuous operation mode while 61% was flushed under artificial pulse (Fig F). Conclusions Pump-specific factors such as LVAD type and programmed flow algorithms lead to unique flow patterns that can be studied using a novel CFD model to better understand and potentially mitigate the risk of downstream LVAD complications.

Diaphragm electromyography results at different high flow nasal cannula flow rates

Heated, humidified, high-flow nasal cannula (HHHFNC) is increasingly being used, but there is a paucity of evidence as to the optimum flow rates in prematurely born infants. We have determined the impact of three flow rates on the work of breathing (WOB) assessed by transcutaneous diaphragm electromyography (EMG) amplitude in infants with respiratory distress or bronchopulmonary dysplasia (BPD). Flow rates of 4, 6 and 8 L/min were delivered in random order. The mean amplitude of the EMG trace and mean area under the EMG curve (AEMGC) were calculated and the occurrence of bradycardias and desaturations recorded. Eighteen infants were studied with a median gestational age of 27.8 (range 23.9–33.5) weeks and postnatal age of 54 (range 3–122) days. The median flow rate prior to the study was 5 (range 3–8) L/min and the fraction of inspired oxygen (FiO2) was 0.29 (range 0.21–0.50). There were no significant differences between the mean amplitude of the diaphragm EMG and the AEGMC and the number of bradycardias or desaturations between the three flow rates.Conclusions: In infants with respiratory distress or BPD, there was no advantage of using high (8 L/min) compared with lower flow rates (4 or 6 L/min) during support by HHHFNC.What is known:• Humidified high flow nasal cannulae (HHHFNC) is increasingly being used as a non-invasive form of respiratory support for prematurely born infants.• There is a paucity of evidence regarding the optimum flow rate with 1 to 8 L/min being used.What is new:• We have assessed the work of breathing using the amplitude of the electromyogram of the diaphragm at three HHHFNC flow rates in infants with respiratory distress or BPD.• No significant differences were found in the EMG amplitude results or the numbers of bradycardias or desaturations at 4, 6 and 8 L/min.

Comparison of Oxygen Adminstration by Nasal Cannula and High Flow Cannula During Bronchoscopy

Comparison of Oxygen Adminstration by Nasal Cannula and High Flow Cannula During Bronchoscopy

High flow nasal cannula: Influence of gas type and flow rate on airway pressure and CO2 clearance in adult nasal airway replicas

BackgroundHigh flow nasal cannula therapy is a form of respiratory support which delivers high flow rates of heated, humidified gas to the nares via specialized cannula. Two primary mechanisms of action attributed to the therapy are the provision of positive airway pressure as well as clearance of CO2-rich exhaled gas from the upper airways. MethodsPhysiologically accurate nose-throat airway replicas were connected at the trachea to a lung simulator, where CO2 was supplied to mimic the CO2 content in exhaled gas. Cannula delivered either air, oxygen or heliox (80/20%volume helium/oxygen) to the replicas at flow rates ranging from 0 to 60 l/min. Five replicas and three cannulas were compared. Tracheal pressure and CO2 concentration were continuously measured. The lung simulator provided breaths with tidal volume of 500 ml and frequency of 18 breaths/min. Additional clearance measurements were conducted for tidal volume and breathing frequency of 750 ml and 27 breaths/min, respectively. FindingsCannula flow rate was the dominant factor governing CO2 concentration. Average CO2 concentration decreased with increasing cannula flow rate, but above 30 L/min this effect was less pronounced. Tracheal positive end-expiratory pressure increased with flow rate and was lower for heliox than for air or oxygen. A predictive correlation was developed and used to predict positive end-expiratory pressure for a given cannula size as a function of supplied flow rate and occlusion of the nares. InterpretationCompared with administration of air or oxygen, administration of heliox is expected to result in similar CO2 clearance from the upper airway, but markedly lower airway pressure.

Deposition studies of aerosol delivery by nasal cannula to infants.

Nasal cannulas are used to provide oxygen support for infants and have been considered as a means for delivering aerosols to the lungs. To measure mucociliary clearance in the lungs of infants with congenital heart defects, we delivered radiopharmaceutical aerosols via a nasal cannula. Here we report on the pulmonary and nasal deposition of these aerosols. A total of 18 infants (median age = 26 days; quartiles = 11-74 days) performed clearance measurements soon before or after corrective cardiac surgery. The regional aerosol deposition was assessed using gamma camera imaging. Cannula flow rate significantly affected pulmonary dosing. Flow rates useful for oxygen support were associated with low pulmonary deposition (2 L/min; mean, 4.5% of deposited dose; range, 2%-9%; n = 7) and high nasal deposition. Much lower cannula flow rates increased the pulmonary deposition (0.2 L/min; mean, 33.5% of deposited dose; range, 15%-51%; n = 5; P = 0.005 vs 2 L/min). The ratio of nose/lung dosing was approximately 26:1 at 2 L/min and 2:1 at 0.2 L/min. Bench studies demonstrated cannula output rates of 10.2 ± 1.7% (2 L/min) and 3.3 ± 0.4% (0.2 L/min) of the loaded nebulizer dose during a 2-minute delivery. Combining in vitro and in vivo results, we estimate that 0.46% of the loaded nebulizer dose reaches the lungs at 2 L/min vs 1.10% at 0.2 L/minduring a 2-minute delivery. With the delivery system used here, pulmonary aerosol delivery via nasal cannula was very inefficient at the flow rates required to provide oxygen support. Even at low flows, nasal deposition was substantial and local toxicity must be considered.

Decrease the flow setting to improve trans-nasal pulmonary aerosol delivery via "high-flow nasal cannula" to infants and toddlers.

Trans-nasal pulmonary aerosol delivery for infants and toddlers has recently gained popularity, however, the reported lung deposition is low. We aimed to investigate the influential factors to improve the delivery. Anatomic airway manikins simulating infant (5 kg) and toddler (15 kg) with collecting filter connected the trachea and breath simulator, were set to represent quiet and distressed breathing. Nasal cannula flow was set at 0.125, 0.25, 0.5, 1, and 2 L/kg/min. A mesh nebulizer (Aerogen) was placed at the inlet of humidifier (Fisher & Paykel) and proximal to patient. Albuterol (5 mg in 1 mL) was nebulized for each condition (n = 3). Drug was eluted from the filter and assayed with UV spectrophotometry (276 nm). Inhaled dose was higher with nebulizer placed at the inlet of humidifier than proximal to patient in all settings, except the infant model at low gas flow settings (0.125 and 0.25 L/kg/min). When nebulizer was placed at the inlet of humidifier, inhaled dose was higher when gas flow was below patient's inspiratory flow than when gas flow exceeded patient's inspiratory flow (8.77 ± 3.84 vs 2.16 ± 1.29%, P < 0.001); aerosol deposition increased as gas flow decreased, with greatest deposition at gas flow of 0.25 L/kg/min (11.29 ± 2.15%). A multiple linear regression identified gas flow as the primary predictor of aerosol delivery. Trans-nasal pulmonary aerosol delivery was significantly improved when gas flow was below patient's inspiratory flow, aerosol deposition increased with decreased nasal cannula flow, with greatest deposition at 0.25 L/kg/min.

High-flow Nasal Cannula Flow Rates, Severe Bronchiolitis

High-flow Nasal Cannula Flow Rates, Severe Bronchiolitis

In vitro evaluation of Capiox FX05 and RX05 oxygenators in neonatal cardiopulmonary bypass circuits with varying venous reservoir and vacuum-assisted venous drainage levels.

The purpose of this study was to evaluate the hemodynamic properties and microemboli capture associated with different vacuum-assisted venous drainage (VAVD) vacuum levels and venous reservoir levels in a neonatal cardiopulmonary bypass circuit. Trials were conducted in 2 parallel circuits to compare the performance of Capiox Baby RX05 oxygenator with separate AF02 arterial filter to Capiox FX05 oxygenator with integrated arterial filter. Arterial cannula flow rate to the patient was held at 500mL/min and temperature maintained at 32°C, while VAVD vacuum levels (0mm Hg, -15mm Hg, -30mm Hg, -45mm Hg, -60mm Hg) and venous reservoir levels (50mL, 200mL) were evaluated in both oxygenators. Hemodynamic parameters measuring flow, pressure, and total hemodynamic energy were made in real time using a custom-made data acquisition system and Labview software. Nearly 10cc bolus of air was injected into the venous line and gaseous microemboli detected using an Emboli Detection and Classification Quantifier. Diverted blood flow via the arterial filter's purge line and mean pressures increased with increasing VAVD levels (P<0.01). Mean pressures were lower with lower venous reservoir levels and were greater in RX05 groups compared to FX05 (P<0.01). Microemboli detected at the preoxygenator site increased with higher VAVD vacuum levels and lower venous reservoir levels (P<0.01). The amount of microemboli captured by the FX05 oxygenator with integrated arterial filter was greater than by the RX05 oxygenator alone, although both oxygenators were able to clear microemboli before reaching the pseudo-patient.

The nocturnal-polysomnogram and “non-hypoxic sleep-disordered-breathing” in children

ObjectiveTo characterize sleep-disordered breathing patterns not related to hypoxia resulting in fragmented sleep in children. MethodsWe reviewed the polysomnogram (PSG) data of children with sleep complaints who were being evaluated for sleep-disordered breathing and had an apnea-hypopnea-index ≤ 3. These data were compared to the recordings of the same children with nasal CPAP administered for one night and to 60 control subjects (children without any sleep complaints). A subgroup of children was monitored with esophageal manometry, but nasal cannula flow data was recorded in all cases. ResultsAbnormal breathing patterns, particularly flow limitation, could be seen with more severity and frequency compared to apnea or hypopnea. The observed abnormal breathing patterns were associated with EEG disturbances. ConclusionsPatterns such as flow-limitation, mouth-breathing, changes in inspiratory and expiratory time, rib-cage and expiratory muscle activity, transcutaneous CO2 electrode changes and snoring noises are all variables that should be systematically reviewed when analyzing nocturnal PSG. Current scoring guidelines emphasizes apnea-hypopnea and hypoxic-sleep disordered breathing and therefore treatment is often much delayed in this population of children with evidence of abnormal breathing patterns. Analysis of the various patterns of abnormal breathing noted above allows recognition of “non-hypoxic” sleep-disordered-breathing (SDB).

Tidal Breathing Measurements at Discharge and Clinical Outcomes in Extremely Low Gestational Age Neonates.

The relationship between respiratory function at hospital discharge and the severity of later respiratory disease in extremely low gestational age neonates is not well defined. To test the hypothesis that tidal breathing measurements near the time of hospital discharge differ between extremely premature infants with bronchopulmonary dysplasia (BPD) or respiratory disease in the first year of life and those without these conditions. Study subjects were part of the PROP (Prematurity and Respiratory Outcomes Program) study, a longitudinal cohort study of infants born at less than 29 gestational weeks followed from birth to 1 year of age. Respiratory inductance plethysmography was used for tidal breathing measurements before and after inhaled albuterol 1 week before anticipated hospital discharge. Infants were breathing spontaneously and were receiving less than or equal to 1 L/min nasal cannula flow at 21% to 100% fraction of inspired oxygen. A survey of respiratory morbidity was administered to caregivers at 3, 6, 9, and 12 months corrected age to assess for respiratory disease. We compared tidal breathing measurements in infants with and without BPD (oxygen requirement at 36 wk) and with and without respiratory disease in the first year of life. Measurements were also performed in a comparison cohort of term infants. A total of 765 infants survived to 36 weeks postmenstrual age, with research-quality tidal breathing data in 452 out of 564 tested (80.1%). Among these 452 infants, the rate of postdischarge respiratory disease was 65.7%. Compared with a group of 18 term infants, PROP infants had abnormal tidal breathing patterns. However, there were no clinically significant differences in tidal breathing measurements in PROP infants who had BPD or who had respiratory disease in the first year of life compared with those without these diagnoses. Bronchodilator response was not significantly associated with respiratory disease in the first year of life. Extremely premature infants receiving less than 1 L/min nasal cannula support at 21% to 100% fraction of inspired oxygen have tidal breathing measurements that differ from term infants, but these measurements do not differentiate those preterm infants who have BPD or will have respiratory disease in the first year of life from those who do not. Clinical trial registered with www.clinicaltrials.gov (NCT01435187).

The Relationship between High Flow Nasal Cannula Flow Rate and Effort of Breathing in Children: Weiler T, Kamerkar A, Hotz J, et al. J Pediatr. 2017;189:66-71

The Relationship between High Flow Nasal Cannula Flow Rate and Effort of Breathing in Children: Weiler T, Kamerkar A, Hotz J, et al. J Pediatr. 2017;189:66-71

Correlation of high flow nasal cannula outlet area with gas clearance and pressure in adult upper airway replicas

BackgroundPrimary benefits of high flow nasal cannula therapy include washout of carbon dioxide rich exhaled gas and increased airway pressures during tidal breathing. This work reports on the influence of high flow nasal cannula outlet area on upper airways gas clearance and tracheal pressures using measurements in five realistic adult nose-throat airway replicas. MethodsTwo commercial high flow nasal cannulas and one generic nasal cannula of varying size were compared. 100% oxygen was supplied via cannulas at flow rates ranging from 30 to 90l/min to replicas originally filled with air, and oxygen concentrations at the larynx and trachea were compared over time. Additionally, and separately, replicas were connected to a mechanical lung simulator to simulate tidal breathing while undergoing high flow nasal cannula therapy, with tracheal pressure–time waveforms recorded. FindingsFaster gas clearance corresponded with higher flow rates (P<0.001), and with smaller cannula outlet area (P<0.001). Observed pressures were in approximate agreement with limited available in-vivo data in the literature. Between 0 and 60L/min cannula flow rates, tracheal positive end expiratory pressures increase was greater with the smallest cannula (∆PPEEP=785SD(185) Pa) compared to the largest cannula (∆PPEEP=380SD(120)Pa). Regression analysis indicates that positive end expiratory pressure is proportional to the square of flow velocities exiting the cannula and nares (R2=0.906). InterpretationSince increased pressure and clearance rate have been associated with improved clinical outcomes in previous studies, our results suggest that smaller cannula outlet area may be preferable.

A modified Montpellier protocol for intubating intensive care unit patients is associated with an increase in first-pass intubation success and fewer complications

BackgroundThe Montpellier protocol for intubating patients in the intensive care unit (ICU) is associated with a decrease in intubation-related complications. We sought to determine if implementation of a simplified version of the Montpellier protocol that removed selected components and allowed for a variety of pre-oxygenation modalities increased first-pass intubation success and reduced intubation-related complications. MethodsA prospective pre/post-comparison of a modified Montpellier protocol in two medical and one medical/surgical/cardiac ICU within a hospital system. The modified eight-point protocol included: fluid administration, ordering sedation, two intubation trained providers, pre-oxygenation with non-invasive positive pressure ventilation, nasal high flow cannula or non-rebreather mask, rapid sequence intubation, capnography, sedation administration, and vasopressors for shock. ResultsPatient characteristics and indications for intubation were similar for the 275 intubations in the control (137) and intervention (138) periods. In the intervention vs. control periods, the modified Montpellier protocol was associated with a significant 16.2% [95% CI: 5.1–30.0%] increase in first-pass intubation success and a 12.6% [95% CI: 1.2–23.6%] reduction in all intubation-related complications. ConclusionA simplified version of the Montpellier intubation protocol for intubating ICU patients was associated with an improvement in first-pass intubation success rates and a reduction in the rate of intubation-related complications.

A Novel Weaning Protocol for High-Flow Nasal Cannula in the PICU.

High-flow nasal cannula use in the PICU continues to increase; however, a protocol for weaning patients has yet to be published. This study aimed to create an efficient and safe protocol for weaning high-flow nasal cannula. A Respiratory Assessment Score was created using two validated scoring systems. A protocol was established for set "holidays" off high-flow nasal cannula, where nasal cannula flow was reduced to age-based low-flow nasal cannula rates if Respiratory Assessment Scores met certain criteria. The PICU at Children's Healthcare of Atlanta at Egleston, a quaternary level hospital affiliated with Emory University. Patients treated in the PICU with high-flow nasal cannula from August 2013 to March 2014. Exclusions included apnea, heliox therapy, oxygen saturations less than 92% with a FIO2 greater than 50%, admitted to PICU less than 6 hours, progression to intubation prior to scoring, or those ordered by physician to not receive holidays based on clinical status. Patients who qualified for a "holiday" based on Respiratory Assessment Score were trialed off high-flow nasal cannula and rescored afterwards to assess tolerance. One hundred thirty-three patients were treated with high-flow nasal cannula, with the most common diagnosis being bronchiolitis (43%). Of these 133 patients, 119 (89.5%) successfully weaned to low-flow nasal cannula within four holiday attempts. Eighty-three patients (70%) weaned with only one attempt. Fourteen patients (10.5%) failed to wean. Reasons for failure were reintubation, increasing flow on high-flow nasal cannula, too high of Respiratory Assessment Score to meet weaning criteria, or slow weaning after failed attempts. Holidays did not precipitate clinical deterioration or lead to immediate intubation. Our study suggests that a high-flow nasal cannula "holiday" protocol is a safe and effective way to successfully wean PICU patients off high-flow nasal cannula. Additional investigation including validation of the scoring system used is warranted.

The Relationship between High Flow Nasal Cannula Flow Rate and Effort of Breathing in Children

To use an objective metric of effort of breathing to determine optimal high flow nasal cannula (HFNC) flow rates in children <3 years of age. Single-center prospective trial in a 24-bed pediatric intensive care unit of children <3 years of age on HFNC. We measured the percent change in pressure∙rate product (PRP) (an objective measure of effort of breathing) as a function of weight-indexed flow rates of 0.5, 1.0, 1.5, and 2.0 L/kg/minute. For a subgroup of patients, 2 different HFNC delivery systems (Fisher & Paykel [Auckland, New Zealand] and Vapotherm [Exeter, New Hampshire]) were compared. Twenty-one patients (49 titration episodes) were studied. The most common diagnoses were bronchiolitis and pneumonia. Overall, there was a significant difference in the percent change in PRP from baseline (of 0.5 L/kg/minute) with increasing flow rates for the entire cohort (P < .001) with largest change at 2.0 L/kg/min (-21%). Subgroup analyses showed no significant difference in percent change in PRP from baseline when comparing the 2 different HFNC delivery systems (P = .12). Patients ≤8 kg experienced a larger percent change in PRP as HFNC flow rates were increased (P = .001) than patients >8 kg. The optimal HFNC flow rate to reduce effort of breathing in infants and young children is approximately 1.5-2.0 L/kg/minute with more benefit seen in children ≤8 kg.

Evaluation of Hemodynamic Performance of a Combined ECLS and CRRT Circuit in Seven Positions With a Simulated Neonatal Patient.

As it is common for patients treated with extracorporeal life support (ECLS) to subsequently require continuous renal replacement therapy (CRRT), and neonatal patients encounter limitations due to lack of access points, inclusion of CRRT in the ECLS circuit could provide advanced treatment for this population. The objective of this study was to evaluate an alternative neonatal ECLS circuit containing either a Maquet RotaFlow centrifugal pump or Maquet HL20 roller pump with one of seven configurations of CRRT using the Prismaflex 2000 System. All ECLS circuit setups included a Quadrox-iD Pediatric diffusion membrane oxygenator, a Better Bladder, an 8-Fr arterial cannula, a 10-Fr venous cannula, and 6 feet of ¼-inch diameter arterial and venous tubing. The circuit was primed with lactated Ringer's solution and packed human red blood cells resulting in a total priming volume of 700 mL for both the circuit and the 3-kg pseudopatient. Hemodynamic data were recorded for ECLS flow rates of 200, 400, and 600 mL/min and a CRRT flow rate of 50 mL/min. When a centrifugal pump is used, the hemodynamic performance of any combined ECLS and CRRT circuit was not significantly different than that of the circuit without CRRT, thus any configuration could potentially be used. However, introduction of CRRT to a circuit containing a roller pump does affect performance properties for some CRRT positions. The circuits with CRRT positions B and G demonstrated decreased total hemodynamic energy (THE) levels at the post-arterial cannula site, while positions D and E demonstrated increased post-arterial cannula THE levels compared to the circuit without CRRT. CRRT positions A, C, and F did not have significant changes with respect to pre-arterial cannula flow and THE levels, compared to the circuit without CRRT. Considering hemodynamic performance, for neonatal combined extracorporeal membrane oxygenation (ECMO) and CRRT circuits with both blood pumps, we recommend the use of CRRT position A due to its hemodynamic similarities to the ECMO circuit without CRRT.

Does an Open Recirculation Line Affect the Flow Rate and Pressure in a Neonatal Extracorporeal Life Support Circuit With a Centrifugal or Roller Pump?

The objective of this study is to evaluate the impact of an open or closed recirculation line on flow rate, circuit pressure, and hemodynamic energy transmission in simulated neonatal extracorporeal life support (ECLS) systems. The two neonatal ECLS circuits consisted of a Maquet HL20 roller pump (RP group) or a RotaFlow centrifugal pump (CP group), Quadrox-iD Pediatric oxygenator, and Biomedicus arterial and venous cannulae (8 Fr and 10 Fr) primed with lactated Ringer's solution and packed red blood cells (hematocrit 35%). Trials were conducted at flow rates ranging from 200 to 600 mL/min (200 mL/min increments) with a closed or open recirculation line at 36°C. Real-time pressure and flow data were recorded using a custom-based data acquisition system. In the RP group, the preoxygenator flow did not change when the recirculation line was open while the prearterial cannula flow decreased by 15.7-20.0% (P < 0.01). Circuit pressure, total circuit pressure drop, and hemodynamic energy delivered to patients also decreased (P < 0.01). In the CP group, the prearterial cannula flow did not change while preoxygenator flow increased by 13.6-18.8% (P < 0.01). Circuit pressure drop and hemodynamic energy transmission remained the same. The results showed that the shunt of an open recirculation line could decrease perfusion flow in patients in the ECLS circuit using a roller pump, but did not change perfusion flow in the circuit using a centrifugal pump. An additional flow sensor is needed to monitor perfusion flow in patients if any shunts exist in the ECLS circuit.

Novel Nasal High Flow Cannula Usability Performance Characteristics

SESSION TITLE: Respiratory Care SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, October 26, 2016 at 01:30 PM - 02:30 PM PURPOSE: Nasal high-flow therapy (HFT), delivers warm, humidified air through a small nasal cannula. In chronic obstructive pulmonary disease (COPD) patients, HFT substantially decreases ventilatory demand during sleep, requiring a nasal cannula suited for extended overnight use as part of the HFT system. The goal of this study was to assess acceptance, usability of two nasal high-flow therapy cannulas thereby comparing the subjective preferences of two cannulas for use with the HFT system. METHODS: In a group of individuals with a spectrum of chronic obstructive pulmonary disease severity, we compared the: 1) acceptability and 2) usability of a new nasal airflow cannula. Twenty participants with COPD (10 women, 10 men; age: 56.2±13.2yrs) and 13 healthcare professionals (4 physician; 5 allied health therapist; 4 medical scientist) with experience using high flow therapy were recruited for the study. Each subject was given two cannulas [Cannula A (Optiflow, Fisher & Paykel, New Zealand) - the reference cannula; Cannula B (AcuCare, ResMed, Australia) - a newly available cannula] in random order. The order of cannulas A and B were randomized and airflow levels between 10 & 60 L/min were administered for 10-20 minutes whilst lying comfortably in bed. Each individual was asked to reposition themselves from their back to each of their sides at least on one occasion. Immediately after using each of the cannulas both the participant and healthcare professional completed acceptability and usability questionnaires (0-10 scale; where 0 is negative and 10 is positive) to determine, preference, ease of use, stability and comfort. RESULTS: COPD patients reported that there was no difference between the two cannulas ease of use and adjustment (A=9.2; B=9.7), comfort (A=8.5, B=8.8), stability (A=9.5, B=9.9), or water droplets forming in the cannula (A=8.9, B=9.8). Healthcare professionals reported that there was no difference between the two cannulas ease of use and adjustment (A=7.8; B=8.2), stability (A=9.2, B=9.3), instructions for use (A=8.7, B=8.3), or removing from the patient (A=8.9, B=9.8). Compared to Cannula B, Cannula A was reported to be slightly more noisy for both the patient and healthcare professional groups (scale point difference 1.2 and 1.7 respectively; p<0.01). In the patient group 20% preferred Cannula A, 70% preferred Cannula B and 10% had no overall preference. In the Healthcare professional group 38% preferred Cannula A, 54% preferred Cannula B and 8% had no preference. CONCLUSIONS: Acceptance and usability of the two nasal high flow cannulas was equivalent, despite less perception of noise generated by the new cannula. CLINICAL IMPLICATIONS: The performance of the new nasal cannula is therefore suited for extended overnight use to evaluate HFT for improving ventilatory efficacy in COPD patients. DISCLOSURE: Jason Kirkness: Grant monies (from industry related sources): Sponsorship Paolo Biselli: Grant monies (from industry related sources): Sponsorship Tamas Otvos: Grant monies (from industry related sources): Sponsorship Alan Schwatrz: Grant monies (from industry related sources): Sponsorship Hartmut Schneider: Grant monies (from industry related sources): Sponsorship Mudiaga Sowho: Grant monies (from industry related sources): Sponsorship The following authors have nothing to disclose: Philip Smith Product is a new nasal cannula, designed to be more comfortable and fit better to ensure proper delivery of airflow or oxygen during treatment.

Left Brachiocephalic Vein Cannulation in Bicaval Venous Drainage Is Safe, Effective, and Technically Advantageous.

Direct cannulation of both venae cavae (bicaval venous cannulation) is the gold standard for right atrial isolation in intracavitary surgery, but there has been no consensus about an alternative site. Therefore, we studied an alternative method for bicaval venous drainage in which the left brachiocephalic vein (LBCV) is cannulated instead of the superior vena cava. From 2012 through 2014, we performed routine LBCV cannulation in 150 consecutive patients as part of bicaval venous drainage before right atrial isolation. We prospectively collected demographic information, operative data, total pump and LBCV cannula flows with their respective calculated and indexed rates, central venous pressures, and perioperative complications. All patients survived surgery. There were no adverse technical outcomes or functional deficits associated with the technique. The mean indexed LBCV cannula flow was 1,520 ± 216 mL/min/m(2), representing an LBCV cannula-to-calculated pump-flow ratio of 64%. The mean central venous pressure during right atrial isolation was 3.7 ± 1.9 mmHg. Cannulation of the LBCV is intrinsically a safe and reproducible procedure with proven hemodynamic adequacy. Its versatility can be an asset to surgical techniques and perfusion methods. Furthermore, the hemodynamic results in our series promise alternative intrathoracic and extracardiac cannulation sites for mini-extracorporeal circulation, on-pump beating-heart procedures, and short-term circulatory assist device implementation.

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.