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PubMed1996

A prospective clinical comparison of two intravenous polyurethane cannulae.

Tissue irritation, as evidenced by phlebitis, associated with Optiva (Johnson & Johnson Medical) and Insyte (Becton Dickinson) polyurethane cannulae was studied. The integrity of the cannulae on removal, the incidence of infection at the cannula site and the factors which influence phlebitis were also examined. One thousand and eight patients had a polyurethane cannula placed for induction of anaesthesia for cardiac surgery. After surgery, the cannula was examined every 24 hours. If evidence of phlebitis occurred, the cannula was removed and sent for culture. All remaining cannulae were removed at 72 hours and the site examined daily for a further three days. There were 503 Optiva and 505 Insyte cannulae studied. The distributions between the two cannulae with respect to patient characteristics, gauge of cannula, number of attempts and difficulty of insertion, cannula site and anaesthetist inserting were similar. The early removal rate for both groups was 47%. Overall phlebitis rate with Optiva was 31% and Insyte 33%. This difference is not statistically significant. The cumulative phlebitis rate increased with time but did not differ between the two types of cannulae. Minor tip distortion or shaft kinking of the cannulae occurred in 16.2% of Optiva and 23.5% of Insyte. This difference is statistically significant and may relate to the slightly more acute taper at the Optiva cannula tip. Both cannulae were similar in clinical performance.

Adolescent↗
PubMed1997

A prospective clinical comparison of two intravenous polyurethane cannulae.

Tissue irritation, as evidenced by phlebitis, associated with Optiva (Johnson & Johnson Medical) and Insyte (Becton Dickinson) polyurethane cannulae was studied. The integrity of the cannulae on removal, the incidence of infection at the cannula site and the factors which influence phlebitis were also examined. One thousand and eight patients had a polyurethane cannula placed for induction of anaesthesia for cardiac surgery. After surgery, the cannula was examined every 24 hours. If evidence of phlebitis occurred, the cannula was removed and sent for culture. All remaining cannulae were removed at 72 hours and the site examined daily for a further three days. There were 503 Optiva and 505 Insyte cannulae studied. The distributions between the two cannulae with respect to patient characteristics, gauge of cannula, number of attempts and difficulty of insertion, cannula site and anaesthetist inserting were similar. The early removal rate for both groups was 47%. Overall phlebitis rate with Optiva was 31% and Insyte 33%. This difference is not statistically significant. The cumulative phlebitis rate increased with time but did not differ between the two types of cannulae. Minor tip distortion or shaft kinking of the cannulae occurred in 16.2% of Optiva and 23.5% of Insyte. This difference is statistically significant and may relate to the slightly more acute taper at the Optiva cannula tip. Both cannulae were similar in clinical performance.

Adolescent↗
PubMed1981

Intestinal cannulation of cattle and sheep with a T-shaped cannula designed for total digesta collection without externalizing digesta flow.

An intestinal cannula was prepared that was designed to have the advantages of a reentrant cannula without permanently exteriorizing digesta flow or adding significantly to the resistance of digesta flow. The cannula was fabricated in the shape of a T from a Teflon fluorocarbon polymer. Total passage of digesta through the lumen of the cannula was accomplished by suturing a support boot around the outside of the intestine at the cannulation site. The support boot prevented the intestine from stretching away from the cannula. Digesta leakage around the barrel of the cannula was eliminated by a special peritoneal ring attached to the cannula in a position that interrupted the continuity of the tubular scar tissue that formed from the intestine alongside the barrel to the skin. The cannula was supported by an outer ring held in place by a simple stainless steel retaining ring. The low external profile of the cannula minimized mechanical disturbance of the cannula and cannula site. Diet consumption and growth rates were normal, and no blockage was encountered in either the duodenal or the ileal cannula with a wide variety of diets, indicating that the cannula added no significant resistance to digesta flow. Total digesta collection or simultaneous collection and addition were easily accomplished with special collection gates. The cannula preparation has a long functional life; in one case, the cannula remained functional for more than 2 1/2 years.

Animals↗
PubMed1998

Insertion of internal jugular temporary hemodialysis cannulae by direct ultrasound guidance--a prospective comparison of experienced and inexperienced operators.

OBJECTIVE: Previous studies have shown that inexperienced operators have a lower success rate than experienced operators for insertion of internal jugular cannulae using the anatomical landmark technique. The object of this study was to determine the rate of successful insertion, incidence of immediate complications and incidence of infection for temporary hemodialysis cannulae inserted under ultrasound guidance by experienced and inexperienced operators. METHODS: The reason for insertion, patient age, reason for failed insertion, immediate complications, duration of cannula survival and reason for removal were recorded prospectively for 107 attempted cannulations by 7 operators in 72 subjects with renal failure. Operators were defined as "experienced" (more than 3 years postgraduate clinical experience and more than 25 previous central vein cannulae inserted) or "inexperienced" (less than 3 years postgraduate clinical experience and less than 3 previous central vein cannulae inserted). Rates of successful cannulation and incidence of complications were compared for experienced and inexperienced operators. Cannula survival without infection was analysed by Kaplan-Meier survival for experienced and inexperienced operators. RESULTS: The overall success rate of cannula insertion at first site was 103/107 (96.3%) with no difference between experienced and inexperienced operators (56/58 vs. 47/49). 103 internal jugular temporary haemodialysis cannulae were inserted into 72 subjects. The only immediate complication was incorrect positioning of the cannula in 6 cases requiring manipulation. The median survival of hemodialysis cannulae was 14 days (range 1-111). 64.1% cannulae functioned for as long as required. Of the remainder, 33/36 were removed because of presumed cannula related infection. There was no difference in the median duration of cannula survival between experienced and inexperienced operators (15 days versus 12 days; Mann-Whitney point estimate = -1.00; 95% confidence interval -6.00, 3.00). p = 0.66) or in the probability of cannula survival without infection by Kaplan Meier analysis. CONCLUSION: We conclude that ultrasound guided temporary haemodialysis cannulation is a safe procedure with a high rate of success, the success rate for inexperienced operators is much higher than previous studies of cannulation using the anatomical landmark technique and the rate of cannula removal due to infection is not influenced by operator experience.

Catheterization, Central Venous↗
PubMed2005

A femoral artery cannula that allows distal blood flow.

OBJECTIVE: A femoral artery cannula is used for certain types of circulatory support but can cause ischemia, especially during prolonged perfusion. This study tests the function of a femoral cannula designed to allow proximal and distal blood flow. METHODS: Five pigs were used in the study. In each animal a distal-flow cannula was implanted in the femoral artery of one leg, and the same-sized standard cannula was implanted in the other. Blood was drained from the left atrium and delivered to the femoral artery through the distal-flow cannula or standard cannula by using a centrifugal pump. An ultrasonic flow probe and microspheres were used to quantify flow and perfusion distal to the cannula. RESULTS: Distal femoral flow and tissue perfusion were present in all animals (5/5) with the distal-flow cannula but only in 1 of 5 animals with the standard cannula (P < .048). Distal flow did not change with pump flow. Mean distal flow at each level of pump flow was higher with the distal-flow cannula (P < .05). Tissue perfusion was also higher with the distal-flow cannula (0.052 +/- 0.028 vs 0.010 +/- 0.022 mL x min(-1) x g(-1), P < .03). CONCLUSIONS: In the swine model the distal-flow cannula allowed greater and more consistent distal flow than the standard cannula. The use of a distal-flow cannula for circulatory support might reduce the risk of distal limb ischemia.

Animals↗
PubMed1985

Conservation of oxygen supply using a reservoir nasal cannula in hypoxemic patients at rest and during exercise.

A reservoir nasal cannula which stores oxygen during exhalation and delivers it as a bolus during inhalation has been reported to conserve oxygen delivery in patients with chronic obstructive pulmonary disease (COPD) at rest. We compared the effects upon arterial oxygen saturation (SaO2) of the reservoir cannula and a standard nasal cannula in hypoxemic obstructed and restricted patients at rest and during exercise. The SaO2 was monitored by ear oximeter. While at rest, 13 obstructed and four restricted patients breathed oxygen from the reservoir cannula at 0.5, 1.0, 1.5, and 2.0 L/min and from a standard cannula at 0.5, 1.0, 2.0, 3.0, and 4.0 L/min. Mean SaO2 was significantly higher with the reservoir cannula compared to the standard cannula at 1.0 and 2.0 L/min (p less than 0.0006) and tended to be higher at 0.5 L/min (p less than 0.1). Seven obstructed patients walked on a level treadmill at 0.75 mph while breathing oxygen at 0.5 and 1.5 L/min from the reservoir cannula and at 1.0 and 3.0 L/min from the standard cannula. The SaO2 during exercise with the reservoir cannula was comparable to that with the standard cannula at approximately half of the oxygen flow rate. The ratio of the oxygen flow rate of the standard to the reservoir cannula to produce 90 percent saturation was estimated and found to be 2.5 +/- 0.8 (mean +/- SD) for patients at rest and 2.9 +/- 1.8 during exercise. We conclude that in hypoxemic patients at rest and during exercise, the reservoir cannula uses less than half the oxygen of a standard cannula to produce similar improvement in SaO2 and thus has advantages of a reduced cost of ambulatory therapy with low-flow oxygen and a longer time permitted away from a stationary source of oxygen.

Carbon Dioxide↗
PubMed2000

Novel dialysis cannulas: are they worth the higher price tag?

Accessory hemodialysis equipment, including dialysis cannulas, usually lack controlled and independent testing before being introduced onto the market. The aim of this study is a prospective comparison of a newly designed curved-tip dialysis cannula with a standard dialysis cannula of the same size from the same manufacturer. Fifteen chronic dialysis patients were enrolled onto a prospective 4-month crossover study. All patients had arteriovenous fistulas, except for two patients with polytetrafluoroethylene grafts. The routinely used standard cannulas were replaced by either a curved-tip 15G cannula or a new standard 15G cannula from the same manufacturer. The two cannulas were compared with respect to puncture-related pain and/or problems and bleeding complications, as well as blood-flow dynamics. Venous and arterial access pressures were recorded at blood-flow rates of 100 to 400 mL/min. Linear regression analyses of arterial and venous pressure profiles showed the same regression lines for the standard and curved-tip cannulas. Plasma haptoglobulin levels and occlusion times necessary to stop bleeding after removal of the cannulas did not differ between the two cannulas. Both patients and nurses independently reported equal puncture-related pain and/or problems for both cannulas on visual analogue scales. No correlation was found between puncture problems reported by nurses and puncture pain reported by patients. The curved-tip cannula does not offer an advantage compared with the less expensive standard cannula. Controlled testing of advertised advantages by manufacturers of accessory equipment should be a prerequisite before introduction into routine clinical treatment.

Adult↗
PubMed2002

A new expandable cannula to increase venous return during peripheral access cardiopulmonary bypass surgery.

Peripheral cannulation for cardiopulmonary bypass (CPB) is of prime interest in minimally invasive open heart surgery. As CPB is initiated with percutaneous cannulae, venous drainage is impeded due to smaller vessel and cannula size. A new cannula was developed which can change shape in situ and therefore may improve venous drainage. An in vitro circuit was set-up with a penrose latex tubing placed between the preload reservoir and the cannula, encasing the cannula's inlet and simulating the vena cava. The preload (P) was stabilised at 2 and at 5 mmHg respectively. The maximum flow rate was determined for 4 conditions: passive venous drainage (PVD) and assisted venous drainage (AVD) using a centrifugal pump at the 2 preload settings. We compared the results of the prototype cannula to classical femoral venous cannulae: basket 28Fr, a thoracic 28Fr and a percutaneous 27Fr. Under PVD conditions and a CVP of 2 mmHg, the prototype cannula's flow rate outperformed the next best cannula by 14% (p=0.0002) and 13% under AVD conditions (p=0.0001). Under PVD conditions and a CVP of 5 mmHg, the prototype cannula outperformed the percutaneous cannula by 19% (p=0.0001) and 14% under AVD conditions (p=0.0002). The new cannula outperforms the classical percutaneous venous cannulae during all of the four conditions tested in vitro.

Cardiopulmonary Bypass↗
PubMed2006

Standardizing nasal cannula oxygen administration in the neonatal intensive care unit.

OBJECTIVE: A multicycle, quality improvement method was used to standardize nasal cannula O2 administration and weaning in the NICU. METHODS: A 2-armed nasal cannula standardized order form (nasal cannula for stable O2 arm and nasal cannula for stable flow arm) was developed after review of the literature, surveying of the practice of NICU physicians and nurse practitioners, and development of consensus among these providers. Outcomes were measured by tracking the distribution of protocol arm chosen, days on O2, weeks on nasal cannula, and disposition of infants who were supported by nasal cannula. Data were collected in an SPSS statistical data set. RESULTS: Of the 90 infants evaluated, 12 were supported on the stable O2 arm and 53 on the stable flow arm for their entire nasal cannula course. Twenty-five infants switched between arms of support. Patients who were on the stable flow arm of the standard order set for their entire nasal cannula course experienced fewer O2 days but more days on nasal cannula. A subpopulation of infants were supported on nasal cannula flow 0.5 to 1.0 L, with fraction of inspired O2 of 21%. When data from the first 10 weeks of observation were compared with that of the second 10 weeks, the rate of discharge on O2 had decreased from 13 (30%) of 44 to 3 (7%) of 39. CONCLUSIONS: The multiple steps of literature review, practice surveys, and consensus-building resulted in enthusiastic reception of the nasal cannula standardized order form. The 2-armed nasal cannula protocol forced caregivers to consider which method of support was most beneficial for each infant who was on nasal cannula and allowed a subpopulation of NICU patients to be supported with a lower fraction of inspired O2 than previously used in the NICU.

Catheterization↗
PubMed1981

Objective evaluation of the efficacy of various venous cannulas.

Six venous cannulas (USCI No. 32, USCI No. 40, USCI No. 44, Sarns No. 40, Sarns two-stage cavoatrial, and Ferguson Argyle No. 40) were tested for efficiency of venous flow during cardiopulmonary bypass, with and without aortic cross-clamping. Each cannula was tested six times in dog models (twice in each of three dogs) and the data were averaged. The tip of the cavoatrial Sarns catheter was positioned as recommended. Two No. 32 USCI caval cannulas were placed either with or without caval snaring. The other cannulas were placed in the right atrium. Arterial flow was constant at 80 ml/kg/min, and aortic pressure averaged 84 mm Hg. Central venous pressure and the right ventricle excluded from the pulmonary artery so that blood which was not drained via the venous cannula was measured. Each single atrial cannula decompressed the right atrium (right atrial pressure 0 to 1 mm Hg) better than two caval cannulas (right atrial pressure 0 to 2 mm Hg). Caval snaring did not empty the right atrium (right atrial pressure 2 to 5 mm Hg) as well as any single cannula. The cavoatrial Sarns catheter did not empty the right atrium as well (right atrial pressure 2 to 4 mm Hg), but drained blood from the inferior vena cava (central venous pressure 0 mm Hg) better than other atrial cannulas (central venous pressure 1 to 5 mm Hg). All of the atrial cannulas performed equally well. The right ventricular vent flow varied between 63 and 70 ml/min with each of the atrial cannulas but rose to 85 ml/min with the cavoatrial Sarns catheter and 190 and 74 ml/min during caval cannulation with and without snaring, respectively. Aortic cross-clamping eliminated coronary sinus flow and decreased right ventricular vent flow. Therefore, a single atrial cannula is more efficient in draining blood from the right side of the heart than are two caval or a cavoatrial cannula. This advantage is negated by aortic cross-clamping.

Animals↗
PubMed2004

Which cannulae fit the Ipas manual vacuum aspiration syringe?

BACKGROUND: The Ipas double-valve manual vacuum aspiration (MVA) syringe is an alternative to electrical vacuum aspiration. METHODS: This study determines which US cannulae (flexible, rigid-straight and rigid-curved) work with the Ipas MVA syringe. Cannulae from Ipas, MedGyn, Berkeley and Milex, in sizes 6-12 mm, were randomized and affixed to the MVA syringe. A pressure gauge was attached to the cannula with rubber tubing. Pressure readings were recorded initially and over 30 s. RESULTS: Milex cannulae were not compatible. For the remaining brands, initial vacuum pressures ranged from 55 to 65 mmHg. Flexible cannulae from Ipas, Berkeley and MedGyn maintained initial pressures without leaks, as did the 6-12-mm straight- and curved-rigid cannulae by Berkeley. Eight of the 13 tested MedGyn rigid cannulae lost >10% pressure over 30 s. CONCLUSION: Several US manufacturers produce cannulae that fit on the Ipas MVA syringe without a leak, including Ipas flexible cannula; Berkeley flexible, rigid-straight and rigid-curve cannulae and MedGyn flexible cannula, but not their rigid cannulae.

Abortion, Induced↗
PubMed1996

Cost-benefit analysis of nasal cannulae in non-tracheally intubated subjects.

We evaluated four nasal cannulae used to deliver oxygen and measure PETC02 in a non-tracheally intubated, healthy population. The effect of various oxygen flow rates on PETC02 and respiratory rate (RR), as well as the cost and relative patient comfort of the cannulae, was compared. In this controlled study, 20 healthy volunteers tested the cannulae using oxygen flow rates of 0 (breathing room air), 2, 4, and 6 L/min. The volunteers rated the comfort of each cannula on a scale from 1 (uncomfortable) to 10 (comfortable). Hospital costs of the cannulae were also compared. All of the cannulae, except the Hospitak nasal cannula (HOS), demonstrated an oxygen flow dependency with respect to PETC02 and RR. The HOS cannula was judged by the study population to be the most comfortable and was the second least expensive cannula tested. From a qualitative standpoint, the carbon dioxide waveform recorded with the HOS cannula was the one least affected by oxygen flow. Of the nasal cannula systems evaluated in this study, the HOS system demonstrated the best cost-benefit ratio, performing well clinically while being comfortable to wear and relatively inexpensive. These conclusions are specific to a healthy population and not to patients with lung disease,those who smoke, or those having a higher ASA classification status. Our evaluation suggests that comfort and clinical performance of nasal cannulae may well depend on device design.

Adult↗
PubMed2002

The use of a side-opening injection cannula in vertebroplasty: a technical note.

STUDY DESIGN: A human cadaveric investigation was conducted to determine the effect that a side-opening injection cannula in monopedicular percutaneous vertebroplasty had on the vertebrae filling pattern. OBJECTIVES: To assess the filling pattern in vertebroplasty using a monopedicular technique, and to compare a standard front-opening filling cannula with a side-opening cannula. SUMMARY OF BACKGROUND DATA: Vertebroplasty is an effective treatment for osteoporotic vertebral fractures. Clinical and biomechanical investigations show its efficacy even in asymmetrical filling patterns. However, the risk of cement extravasation is a major concern with this technique. METHODS: Two different bone cement-injecting cannulas were compared: a standard front-opening cannula (8 gauge, 6 inches long) and a cannula of the same dimensions with a side-opening at its distal end. Eight pairs of osteoporotic nonfractured cadaver vertebrae (T10-T11) were augmented with low-viscosity polymethylmethacrylate under axial C-arm control. The filling pattern was assessed semiquantitatively. The cross-section in its lateral extension was divided into four equal bands, and the appearance of the cement in each respective zone was assessed after cement injections of 2, 4, and 8 mL. The extravasation of bone cement also was monitored. RESULTS: With the side-opening cannula, the cement flow reached Zone 3 in six of eight cases, whereas with the front-opening cannula, the polymethylmethacrylate was observed in Zone 3 in only three cases. In no case was the cement observed in Zone 4. In five of eight cases using front-opening cannulas, extravasation into the vessels was observed after 3 to 4 mL of bone cement had been injected. No extravasation was noted with the use of the side-opening cannula unless the amount of cement exceeded 8 mL. CONCLUSIONS: A side-opening cannula can improve the cement-filling pattern in monopedicular vertebroplasty, as compared with a standard front-opening cannula. The risk of extravasation is diminished if the cement flow is directed medially.

Bone Cements↗
PubMed2003

A prototype paediatric venous cannula with shape change in situ.

During cardiopulmonary bypass (CPB), venous drainage may be impeded due to small vessel and cannula size or chattering, thus, blood return to the heart-lung machine is reduced. We designed a self-expandable prototype cannula, which is able to maintain the vein open and overcome this problem and analysed its performance capability. This prototype and several other cannulae were tested using an access vessel diameter of 7 mm. An in vitro circuit was set up with a 10 mm penrose latex tube simulating the patient's vein placed between the patient preload reservoir and the cannula, encasing the cannula's inlet(s). Maximum flow rate was determined for passive venous drainage (PVD) at preloads (P) of 2 and 4 mmHg. We compared these results to three classic single-stage venous cannulae: basket tip, thoracic drain and percutaneous tip. By comparing the other cannulae to the prototype, under PVD conditions and a central venous pressure (CVP) of 2 mmHg, the prototype cannula's flow rate (1.32 +/- 0.04 L/min) outperformed the basket type (the best performing comparator) (1.02 +/- 0.08 L/min) by 23% (p < 0.005). When the preload was increased to 4 mmHg under PVD conditions, the same trend was noted with the prototype cannula (1.65 +/- 0.05 L/min), outperforming the basket cannula's value (1.26 +/- 0.05 L/min) by 24% (p < 0.001). This new cannula design provides superior flow characteristics, under all test conditions, compared to the classic single-stage venous cannulae used for paediatric CPB surgery.

Blood Flow Velocity↗
PubMed1985

Assessment of thromboresistance of intravenous cannulae by 125I-fibrinogen scanning.

Assessment of potentially thromboresistant polymers and other materials has been impeded by the lack of a simple and safe test procedure in man. This report describes the use of a portable gamma radiation detector to assess accumulation of 125I-fibrinogen in thrombi related to intravenous cannulae. The method was first employed in 19 dogs and one sheep with FEP-Teflon forelimb intravenous cannulae which were scanned for up to 6 h after insertion. Results were compared with findings at post mortem examination. Eleven thrombi developed, nine of which emitted more than 3500 counts per minute; eight of these (89%) were detected by external scanning. The smallest thrombus detected weighed 0.7 mg. The method did not distinguish between thrombus and hematoma. Fifty FEP-Teflon cannulae were then studied in 39 patients after injection of 100 microCi 125I-fibrinogen. Cannulae and control sites were scanned twice daily and an independent blind clinical appraisal was performed by an experienced nurse. A rise in percentage uptake (count at a limb site/heart count X 100) of 20 or a difference of 40 between adjacent sites was regarded as a positive test. Scans became positive up to 30 h before clinical evidence of phlebitis was observed. The interval between insertion and thrombosis of both large and small cannulae detected by scanning was significantly shorter than that determined by clinical assessment (p less than 0.001). Physical signs of phlebitis were noted with 58% of large cannulae (16 or 18 gauge)and 33% of small cannulae (22 gauge) at the time of removal. Positive 125I-fibrinogen tests were obtained with 70% of large cannulae and 75% of small cannulae. 125I-fibrinogen scanning is a safe simple sensitive technique to detect thrombosis related to intravenous cannulae. The test should enable comparisons of different cannula materials in man.

Animals↗
PubMed1995

Effect of cannula length on aortic arch flow: protection of the atheromatous aortic arch.

Atheromatous disease in the transverse aortic arch is associated with an increased incidence of perioperative stroke. In addition, tissue erosion in the aortic arch is caused by the high-velocity jet emerging from an aortic cannula during cardiopulmonary bypass (CPB), termed the "sandblast effect". To quantify this phenomenon, flow in the aortic arch was measured intraoperatively by epiaortic ultrasonography in 18 patients undergoing CPB. All were cannulated in the ascending aorta, 10 with a short (1.5 cm) cannula and 8 with a long (7.0 cm) cannula. The peak forward aortic flow velocities (mean +/- standard deviation) measured on the caudal luminal surface of the aortic arch were 0.80 +/- 0.23 m/s off CPB and 2.42 +/- 0.69 m/s on CPB (p < 0.001) for the short cannula and 0.53 +/- 0.20 m/s off CPB and 0.18 m/s on CPB for the long cannula. Thus, during CPB the peak forward aortic flow velocity with the short cannula was significantly greater (p < 0.001) than before CPB, whereas the long cannula produced a lower peak forward aortic flow velocity during CPB. Furthermore, Doppler examination revealed severe turbulence in the aortic arch in all patients with a short cannula. No arch turbulence, however, was seen in 7 patients with a long cannula, and only mild turbulence appeared in the remaining patient with a long cannula. These results show that use of a long aortic cannula results in a significant decrease in peak forward aortic flow velocity and turbulence in the aortic arch during CPB, which may reduce the risk of erosion or disruption of existing atheroma and ensuing embolic complications.

Aorta, Thoracic↗
PubMed2002

A new expandable venous cannula for minimal access heart surgery.

BACKGROUND: During percutaneous cannulation, the diameter of the venous cannula is determined by the size of the access site. To limit this restriction, the Smart cannula (Cardiosmart Ltd., Fribourg, Switzerland) has been developed. Because its design allows self-expansion within the recipient vein, diameter restriction is limited to the access site. METHODS: In 6 calves (78 +/- 4.3 kg), the jugular vein and the carotid artery were cannulated through a cervicotomy. The Smart cannula was tested against three percutaneous cannulas with a diameter of 27, 25, and 21F, respectively. Stenotic percutaneous access to the vein was simulated by 1-cm wide tape encircling the vein that could be adjusted to a diameter of 27, 25, and 21F, respectively. The maximal flow rate, reached with stable reservoir level and a negative pressure of 44 mm Hg, was determined three times for each access size with the Smart cannula (one size fits all) and the corresponding percutaneous cannula successively. RESULTS: For an access size of 27F, the flow of the Smart cannula was 5.7 +/- 0.4 L/min and that of the percutaneous cannula was 4.3 +/- 0.2 L/min (p < 0.0001); for 25F, flow rates were 5.6 +/- 0.5 and 3.9 +/- 0.2 L/min, respectively (p < 0.0001); and for 21F, the flow rates were 4.3 +/- 0.4 and 2.7 +/- 0.3 L/min, respectively (p < 0.0001). The percentage increase of flow for the 27, 25, and 21F sizes were 34% +/- 9%, 42% +/- 16%, and 53% +/- 18%, respectively (one-way analysis of variance, p = 0.014). CONCLUSIONS: For the present set-up, the Smart cannula outperforms commercially available percutaneous cannulas. The smaller the size of the insertion site, we observed a higher gain of flow with the Smart cannula.

Animals↗
PubMed1997

Retaining extracorporeal membrane oxygenation cannulae after extracorporeal support in the neonate: is it safe?

The retention of extracorporeal membrane oxygenation (ECMO) cannulae of ECMO is discontinued was originally developed to avoid reexploration of the neck in patients who may require a second course of ECMO. Because of the incidence, at the authors' institution, of thrombi noted on the ends of retained cannulae and their potential to cause significant morbidity, a critical review of this procedure was initiated. A telephone survey of 72 Extracorporeal Life Support Organization (ELSO) centers was conducted, and ELSO registry forms were requested for patients who had their cannulae retained. Twenty-four of these centers had performed the procedure of retaining ECMO cannulae. There were 324 neonatal and pediatric patients who had their cannulae retained, with 41 patients (12%) requiring a second course of ECMO and 17 of 41 (41%) surviving the second course. Twelve of the 24 ELSO centers that retain cannulae have reported complications. Analyses of the patients who had their cannulae retained showed that the three best predictors for requiring a second course of ECMO were the diagnosis of congenital diaphragmatic hernia (CDH) a high oxygenation index just before the initiation of ECMO, and a lengthy first ECMO course. The only difference between the survivors and nonsurvivors of the second course of ECMO was the length of the first ECMO course (P < .05). Five of the 25 patients who required two courses of ECMO had serious complications from their retained cannulae and all were nonsurvivors. The authors conclude that patients with retained ECMO cannulae are at high risk for developing thrombi, which can lead to severe embolic events. Therefore, the procedure of retaining cannulae should only be used in patients at high risk for requiring a second course of ECMO and not for the convenience of surgical availability to remove the cannulae.

Catheters, Indwelling↗