Biomedical subjects

Judith Horisberger

Publications and source records attributed to Judith Horisberger.

15 recordsLinked to original sources

PubMed2007

A novel device for reducing hemolysis provoked by cardiotomy suction during open heart cardiopulmonary bypass surgery: a randomized prospective study.

Since the inception of cardiopulmonary bypass (CPB), little progress has been made concerning the design of cardiotomy suction (CS). Because this is a major source of hemolysis, we decided to test a novel device (Smartsuction [SS]) specifically aimed at minimizing hemolysis during CPB in a clinical setting. Block randomization was carried out on a treated group (SS, n=28) and a control group (CTRL, n=26). Biochemical parameters were taken pre-, peri-, and post CPB and were compared between the two groups using the Student's t-test with statistical significance when P<0.05. No significant differences in patient demographics were observed between the two groups. Lactate dehydrogenase (LDH) and plasma free hemoglobin (PFH) pre-CPB were comparable for the CTRL and SS groups, respectively. LDH peri-CPB was 275+/-100 U/L versus 207+/-83 U/L for the CTRL and SS groups, respectively (P<0.05). PFH was 486+/-204 mg/L versus 351+/-176 mg/L for the CTRL and SS groups, respectively (P<0.05). LDH post CPB was 354+/-116 U/L versus 275+/-89 U/L for the CTRL and SS groups, respectively (P<0.05). PFH was 549+/-271 mg/L versus 460+/-254 mg/L for the CTRL and SS groups, respectively (P<0.05). Preoperative hematocrit (Hct) of 43+/-5% (CTRL) versus 37+/-5% (SS), and hemoglobin (Hb) of 141+/-16 g/L (CTRL) versus 122+/-17 g/L (SS) were significantly lower in the SS group. However, when normalized (N), the SS was capable of conserving Hct, Hb, and erythrocyte count perioperatively. Erythrocytes (N) were 59+/-5% (CTRL) versus 67+/-9% (SS); Hct (N) was 59+/-6% (CTRL) versus 68+/-9% (SS), and Hb (N) was 61+/-6% (CTRL) versus 70+/-10% (SS) (all P<0.05). This novel SS device evokes significantly lowered blood PFH and LDH values peri- and post CPB compared with the CTRL blood using a CS system. The SS may be a valuable alternative compared to traditional CS techniques.

Cardiac Surgical Procedures↗

PubMed2006

A novel technique using echocardiography to evaluate venous cannula performance perioperatively in CPB cardiac surgery.

OBJECTIVE: Transthoracic echocardiography (TTE) has been used clinically to disobstruct venous drainage cannula and to optimise placement of venous cannulae in the vena cava but it has never been used to evaluate performance capabilities. Also, little progress has been made in venous cannula design in order to optimise venous return to the heart lung machine. We designed a self-expandable Smartcanula (SC) and analysed its performance capability using echocardiography. METHODS: An epicardial echocardiography probe was placed over the SC or control cannula (CTRL) and a Doppler image was obtained. Mean (V(m)) and maximum (V(max)) velocities, flow and diameter were obtained. Also, pressure drop (DeltaP(CPB)) was obtained between the central venous pressure and inlet to venous reservoir. LDH and Free Hb were also compared in 30 patients. Comparison was made between the two groups using the student's t-test with statistical significance established when p<0.05. RESULTS: Age for the SC and CC groups were 61.6+/-17.6 years and 64.6+/-13.1 years, respectively. Weight was 70.3+/-11.6 kg and 72.8+/-14.4 kg, respectively. BSA was 1.80+/-0.2 m(2) and 1.82+/-0.2 m(2), respectively. CPB times were 114+/-53 min and 108+/-44 min, respectively. Cross-clamp time was 59+/-15 min and 76+/-29 min, respectively (p=NS). Free-Hb was 568+/-142 U/l versus 549+/-271 U/l post-CPB for the SC and CC, respectively (p=NS). LDH was 335+/-73 mg/l versus 354+/-116 mg/l for the SC and CC, respectively (p=NS). V(m) was 89+/-10 cm/s (SC) versus 63+/-3 cm/s (CC), V(max) was 139+/-23 cm/s (SC) versus 93+/-11 cm/s (CC) (both p<0.01). DeltaP(CPB) was 30+/-10 mmHg (SC) versus 43+/-13 mmHg (CC) (p<0.05). A Bland-Altman test showed good agreement between the two devices used concerning flow rate calculations between CPB and TTE (bias 300 ml+/-700 ml standard deviation). CONCLUSIONS: This novel Smartcanula design, due to its self-expanding principle, provides superior flow characteristics compared to classic two stage venous cannula used for adult CPB surgery. No detrimental effects were observed concerning blood damage. Echocardiography was effective in analysing venous cannula performance and velocity patterns.

Adult↗

PubMed2006

Prevention of cryoprecipitation during cardiopulmonary bypass in a patient with HIV-HCV co-infections.

BACKGROUND: There are no guidelines for the management of patients with cryoglobulins during cardiopulmonary bypass (CPB) necessitating core hypothermia. OBJECTIVE: To evaluate a simple, pragmatic protocol of in vitro temperature-dependent cryoprecipitation of serum in patients with cryoglobulinemia before elective cardiac surgery with CPB. METHODS: A 44-year-old female patient was known for chronic hepatitis C and type III cryoglobulinemia. Elective surgery was planned for an aortic arch aneurysm. A differential serum cryoprecipitation profile was established in vitro prior to surgery. RESULTS: Whereas, at temperatures < or = 15 degrees C, cryoglobulin levels were > or = 0.112 g/L (normal value < 0.05 g/L), at 20 degrees C and above, the precipitate was < or = 0.016 g/L. Accordingly, surgery was performed without any cryoglobulin-related complications at an extracorporeal circulation temperature of 22-24 degrees C, to minimise the risk of cryoprecipitation. CONCLUSION: In elective cases of surgery with CPB and hypothermia, temperature-dependent differential serum cryoprecipitation profile may be an easy and efficient way to assess a safe peroperative level of temperature to avoid complications due to cryoglobulins, without enhancing the patient's tissue ischemia risks.

Adult↗

PubMed2005

The Smartcanula: a new tool for remote access perfusion in limited access cardiac surgery.

Devices for venous cannulation have seen significant progress over time: the original, rigid steel cannulas have evolved toward flexible plastic cannulas with wire support that prevents kinking, very thin walled wire wound cannulas allowing for percutaneous application, and all sorts of combinations. In contrast to all these rectilinear venous cannula designs, which present the same cross-sectional area over their entire intravascular path, the smartcanula concept of "collapsed insertion and expansion in situ" is the logical next step for venous access. Automatically adjusting cross-sectional area up to a pre-determined diameter or the vessel lumen provides optimal flow and ease of use for both, insertion and removal. Smartcanula performance was assessed in a small series of patients (76 +/- 17 kg) undergoing redo procedures. The calculated target pump flow (2.4 L/min/m2) was 4.42 +/- 61 L/ min. Mean pump flow achieved during cardiopulmonary bypass was 4.84 +/- 87 L/min or 110% of the target. Reduced atrial chatter, kink resistance in situ, and improved blood drainage despite smaller access orifice size, are the most striking advantages of this new device. The benefits of smart cannulation are obvious in remote cannulation for limited access cardiac surgery, but there are many other cannula applications where space is an issue, and that is where smart cannulation is most effective.

Cardiac Surgical Procedures↗

PubMed2004

Right atrial surgery with unsnared inferior vena cava.

Right atrial procedures require snaring the venous cannulas to prevent air entrapment in the venous line. In particular situations with complex congenital morphology and/or presence of severe pericardial adhesions the right atrial opening without the inferior vena cava cannula in the surgical field and without dissecting and snaring the inferior vena cava itself, might substantially facilitate the surgical technique, provided an adequate venous drainage is assured to avoid flow reduction or circulatory arrest. In several patients with congenital or acquired heart disease with potentially complicated venous drainage, like extracardiac Fontan procedure and tricuspid valve replacement, cardiopulmonary bypass was conducted either on normothermia (congenital lesions) or with mild hypothermia (acquired disease), with 3 l/min per m(2) flow index and venous drainage through femoral vein cannulation. The right atrium was opened without snaring the inferior vena cava, never provoking reduction of the venous drainage nor air locks in the venous line. This approach substantially enhanced the surgical exposure and therefore facilitated the operative technique without any negative consequence to the patients. Right atrial surgery on cardiopulmonary bypass without direct cannulation and snaring of both superior and inferior vena cava is feasible without flow reduction for surgeons taking care of both congenital and acquired cardiac lesions.

Cardiac Surgical Procedures↗

PubMed2004

Vascular access for cardiopulmonary bypass procedures.

Since the initiation of cardiac surgery using cardiopulmonary bypass, little progress has been made concerning the design of catheters for vascular access. However, in the last few years, research in this specialized field has established that catheter performance not only depends on size but also on the catheter's design. The catheter's drainage hole surface area correlates with its performance, i.e., flow; the ratio of the catheter's diameter to the patient's vein diameter also correlates with flow. These findings should influence the design of future models. An example is presented with the development of the Smartcanula which maximizes hole surface area and minimizes the wall thickness in order to optimize flow rate and vascular access to the patient.

Cardiopulmonary Bypass↗

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↗

PubMed2003

Miniaturization in cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) remains the key technology for more complex cardiac operations. The perfusion equipment used nowadays has seen tremendous progress since its introduction into clinical practice 50 years ago. However, overall, CPB is still far from perfect. Major haemodilution is not only a problem for red cell-dependent gas transport, but also for the platelet and humeral factor-dependent coagulation, the protein-dependent intravascular oncotic pressure and so forth. Reduction of the priming volume through further miniaturization of CPB equipment is, therefore, the most obvious next step. A systematic approach needs to optimize all CPB components, including pumps, oxygenator/heat exchanger structures, filters, reservoirs, cardiotomy suction, tubings and cannulas. This report provides an update of already commercially available low prime perfusion devices (e.g., the CORx integrated pump-oxygenator) as well as promising prototypes like the smart suction system and the smartcanula.

Cardiopulmonary Bypass↗

PubMed2003

Limitations using the vacuum-assist venous drainage technique during cardiopulmonary bypass procedures.

Vacuum-assist venous drainage (VAVD) can increase venous blood return during cardiopulmonary bypass (CPB) procedures. However, the negative pressure created in the closed cardiotomy reservoir can be transmitted to the oxygenator if a nonocclusive or centrifugal arterial pump is used, resulting in bubble transgression (BT) from the gas to blood compartment of the oxygenator. We analyzed the vacuum pressure required to produce BT using an in vitro circuit including successively a closed reservoir, a pump (centrifugal or roller), and an oxygenator. A constant hydrostatic pressure was maintained onto the oxygenator. Vacuum was applied on the cardiotomy reservoir, progressively increasing negative pressure from 0 to -80 mmHg and monitoring BT with a bubble detector. Six different oxygenators were compared. A partially occlusive roller pump and a centrifugal pump were compared to a control, which was without any pump. A mean negative pressure of -53 +/- 7 mmHg was necessary to produce BT in all the oxygenators in the absence of a pump. The presence of a centrifugal pump between the reservoir and the oxygenator significantly increased the negative pressure required to produce BT compared to the control (-67 +/- 7 mmHg, p < .05). No bubbles were detected using the roller pump (> -80 mmHg needed for BT), thus statistically significant when compared to the centrifugal pump (p < .05). The centrifugal pump offers significant resistance to BT but not as much compared to the roller pump, though BT cannot be prevented if the pump is turned off while the vacuum remains on the reservoir. Therefore, VAVD is a safe technique as long as the perfusionist stops the vacuum when the arterial pump is no longer in use.

Adult↗

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↗

PubMed2002

A new concept of integrated cardiopulmonary bypass circuit.

OBJECTIVE: Standard cardiopulmonary bypass (CPB) circuits with their large surface area and volume contribute to postoperative systemic inflammatory reaction and hemodilution. In order to minimize these problems a new approach has been developed resulting in a single disposable, compact arterio-venous loop, which has integral kinetic-assist pumping, oxygenating, air removal, and gross filtration capabilities (CardioVention Inc., Santa Clara, CA, USA). The impact of this system on gas exchange capacity, blood elements and hemolysis is compared to that of a conventional circuit in a model of prolonged perfusion. METHODS: Twelve calves (mean body weight: 72.2+/-3.7 kg) were placed on cardiopulmonary bypass for 6 h with a flow of 5 l/min, and randomly assigned to the CardioVention system (n=6) or a standard CPB circuit (n=6). A standard battery of blood samples was taken before bypass and throughout bypass. Analysis of variance was used for comparison. RESULTS: The hematocrit remained stable throughout the experiment in the CardioVention group, whereas it dropped in the standard group in the early phase of perfusion. When normalized for prebypass values, both profiles differed significantly (P<0.01). Both O2 and CO2 transfers were significantly improved in the CardioVention group (P=0.04 and P<0.001, respectively). There was a slightly higher pressure drop in the CardioVention group but no single value exceeded 112 mmHg. No hemolysis could be detected in either group with all free plasma Hb values below 15 mg/l. Thrombocyte count, when corrected by hematocrit and normalized by prebypass values, exhibited an increased drop in the standard group (P=0.03). CONCLUSION: The CardioVention system with its concept of limited priming volume and exposed foreign surface area, improves gas exchange probably because of the absence of detectable hemodilution, and appears to limit the decrease in the thrombocyte count which may be ascribed to the reduced surface. Despite the volume and surface constraints, no hemolysis could be detected throughout the 6 h full-flow perfusion period.

Animals↗

PubMed2002

Flow dynamic comparison of peripheral venous cannulas used with centrifugal pump assistance in vitro.

Because of the risk of vein collapse, the benefits of using a centrifugal pump to assist venous drainage for cardiopulmonary bypass are limited when the tips of peripheral cannulas are maintained within the vena cava. Using a mock circuit including 20 mm diameter latex tubing to mimic a vena cava, we compared the performance of 6 commercially available peripheral venous cannulas and attempted to determine potential factors influencing maximal flow drainage before vein collapse. A close correlation was observed with the total hole area of the cannula. Best performance (5.10 +/- 0.08 L/min) was obtained with an 8 mm internal diameter (ID) cannula and 343 mm2 total hole area. A larger cannula (ID 9.2 mm) with only 209 mm2 total hole area drained 5.03 +/- 0.05 L/min whereas a smaller cannula (ID 6.7 mm) with a total hole area of 586 mm2 also allowed a similar flow of 5.03 +/- 0.12 L/min. Therefore, the total hole area appears to be a critical factor in designing peripheral cannulas used in restricted chambers such as vena cavae.

Cardiopulmonary Bypass↗

PubMed2002

[ECMO and cardiopulmonary support].

ECMO (extracorporeal membrane oxygenation) may be viewed as a prolonged cardiopulmonary bypass allowing for a prolonged cardio-respiratory support. Since its introduction in the 60's, its indication has expanded from acute respiratory failure to acute cardiac failure refractory to conventional treatments. The target group involves mainly those patients presenting with a cardiogenic shock following cardiac surgery or acute myocardial infarction. The advantages of this form of circulatory support, when compared with long-term ventricular assist devices, are its less invasive aspect, its ease of implantation and its reduced cost. However, its main limitation lies in its limited duration of 7 to 10 days, in particular because of hemorrhage complications. Currently, ECMO provides a temporary hemodynamical stability in order to perform an invasive cardiac treatment (coronary bypass or percutaneous dilatation), or to assess the eligibility of the patient for a long-term ventricular assist device, which will enable to wait for the availability of an allograft. The latter scenario is crucial nowadays because of the severe lack of organ donors, which is the leading cause of death among patients waiting for a heart transplant.

Cardiac Output, Low↗

PubMed2002

[Paediatric mechanical cardiac assistance].

The mechanical cardiac assistance, once limited only to the adult patients, is now progressively extended to the paediatric population, including neonates. Currently for children with cardiorespiratory insufficiency requiring for a mechanical assistance there are available several options: Intra-Aortic Balloon Pump, Extra-Corporeal Membrane Oxygenation (ECMO) et le Ventricular Assist Device. From April 1999 in our Department of Cardiovascular Surgery at CHUV 8 children, including 4 neonates, have been treated with ECMO. Indications, contra-indications, advantages, disadvantages, results and complications of the available options of paediatric mechanical cardiac assistance are described.

Child↗

PubMed2002

[Long-term mechanical circulatory support for terminal cardiac insufficiency refractory to medical treatment].

Constant progress has been made over the years in order to improve the performance of mechanical circulatory support devices. After the introduction of portable blood pump systems into clinical practice, we now study the performance characteristics of totally implantable mechanical circulatory support systems which do not require percutaneous drive lines or percutaneous electrical wiring. As a matter of fact, transcutaneous energy transfer is now achieved by induction, and pump controller performance read-out and pump parameter adjustment is performed by telemetry. The indication for clinical use of such devices has to be evaluated carefully. Mainly patients in need of a heart transplant but having contraindications to move forward (advanced age, former neoplasm, persistent antibodies) have benefits from such devices as destination therapy.

Equipment Design↗