Thrombus formation on the balloon of heparin-bonded pulmonary artery catheters: an ultrastructural scanning electron microscope study

Cephalad misplacement of a pulmonary artery catheter in a patient with a preexisting Hickman catheter

Background

Pulmonary artery catheter insertion is a routine practice in high-risk patients undergoing cardiac surgery. However, pulmonary artery catheter insertion is associated with numerous complications that can be devastating to the patient. Incorrect placement is an overlooked complication with few case reports to date.

Case presentation

An 18-year-old male patient underwent elective mitral valve replacement due to severe mitral valve regurgitation. The patient had a history of synovial sarcoma, and Hickman catheter had been inserted in the right internal jugular vein for systemic chemotherapy. We made multiple attempts to position the pulmonary artery catheter in the correct position but failed. A chest radiography revealed that the pulmonary artery catheter was bent and pointed in the cephalad direction. Removal of the pulmonary artery catheter was successful, and the patient was discharged 10 days after the surgery without complications.

Conclusions

To prevent misplacement of the PAC, clinicians should be aware of multiple risk factors in difficult PAC placement, and be prepared to utilize adjunctive methods, such as TEE and fluoroscopy.

Heparin-bonded catheters for prolonging the patency of central venous catheters in children

BACKGROUND

Central venous catheters (CVCs) are a mainstay in the management of critically ill children. However, these catheters are associated with mechanical and infectious complications which reduce their life span. Heparin bonding of catheters has shown promise in animal studies and in adults. This is the first update of a review published in 2007.

OBJECTIVES

The primary objective was to determine the effect of heparin-bonded CVCs on the duration of catheter patency in children. Secondary objectives were to determine the effects of heparin-bonded catheters on catheter-related thrombosis, occlusion, blood stream infection and side effects.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched August 2013) and CENTRAL (2013, Issue 7). The authors searched MEDLINE (1946 to week 3 August 2013).

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials of heparin-bonded catheters versus non-heparin bonded catheters or antibiotic-impregnated catheters that reported on any of the prespecified outcomes, without language restriction.

DATA COLLECTION AND ANALYSIS

We assessed the methodological quality of the trials using the information provided in the studies and by contacting authors. We extracted data and estimated the effect size reported as risk ratio (RR), risk difference (RD) or number needed to treat (NNT), as appropriate.

MAIN RESULTS

We included two eligible studies with a total of 287 participants; both had good methodological quality. There was no difference in the duration of catheter patency between heparin-bonded and non-heparin bonded catheters (median duration seven days versus six days) reported in one study. There was no difference in the risk of catheter-related thrombosis (two studies, RR 0.34, 95% CI 0.01 to 7.68; I(2) = 80%; RD -0.06, 95% CI -0.17 to 0.06). Data from one study revealed a statistically significant reduction in the risk of catheter occlusion (RR 0.06, 95% CI 0.00 to 1.07; RD -0.08, 95% CI -0.13 to -0.02; NNT 13, 95% CI 8 to 50), catheter-related blood stream infections (RR 0.06, 95% CI 0.01 to 0.41; RD -0.17, 95% CI -0.25 to -0.10; NNT 6, 95% CI 4 to 10) and catheter colonization (RR 0.21, 95% CI 0.06 to 0.71; RD -0.11, 95% CI -0.19 to -0.04; NNT 9, 95% CI 5 to 25) in the heparin-bonded catheter group. The second study did not report on these outcomes. There was no significant difference in risk of thrombocytopenia after catheter placement (RR 0.73, 95% CI 0.38 to 1.39; RD -0.02, 95% CI -0.10 to 0.07).

AUTHORS' CONCLUSIONS

Two eligible studies on the use of heparin-bonded catheters versus placebo in children were identified. Meta-analysis of the two studies revealed no reduction in catheter-related thrombosis with heparin-bonded catheters. One study reported a reduction in catheter-related blood stream infection and colonization following the use of heparin-bonded catheters. The strength of evidence is low and further well-designed multicenter randomized controlled trials are warranted.

Insertion of central venous catheters induces a hypercoagulable state

BACKGROUND

Central venous catheters (CVCs) increase the risk of venous thromboembolism. We have previously demonstrated that pulmonary artery catheters are associated with a hypercoagulable state in an animal model and in patients. The purpose of this study is to determine whether the insertion of a CVC is associated with a similar response.

METHODS

ANIMAL

7F femoral artery catheters were placed in healthy anesthetized swine (N = 16). Serial arterial blood samples were drawn immediately before and after an 8.5F jugular vein CVC and then for 3 hours after CVC removal. Samples were analyzed using kaolin-activated thromboelastography (TEG) at precisely 2 minutes. Human: An institutional review board-approved prospective observational trial was conducted, with informed consent, in patients with critical illness (N = 8) at a Level I trauma center. Blood was drawn from indwelling arterial catheters immediately before and 60 minutes after CVC insertion. Samples were stored in sodium citrate for 15 minutes before TEG. Routine and special coagulation tests were performed on stored samples in the hospital pathology laboratory.

RESULTS

Insertion of a CVC decreased TEG clotting time (R) by 55% in swine and by 29% in humans (p < 0.001 and 0.019, respectively). Initial clot formation time (K) was reduced by 41% in swine and by 36% in humans (p = 0.003 and 0.019). Fibrin cross-linking (α) was accelerated by 28% in swine and by 17% in humans (p = 0.007 and 0.896), but overall clot strength (maximum amplitude) was not affected. There was no change in routine or special coagulation factors, including von Willebrand factor, antithrombin III, prothrombin time, international normalized ratio, or activated partial thromboplastin time. In animals, the hypercoagulable TEG response was persistent for 3 hours after CVC removal and was prevented by pretreatment with enoxaparin (n = 4) but not heparin (n = 2).

CONCLUSION

In healthy swine and patients with critical illness, a systemic hypercoagulable state occurred after CVC insertion, and this may partially account for an increased risk of venous thromboembolism. However, because the sample size was small and not powered to detect changes in coagulation proteins, no inferences can be made about the mechanism for the hypercoagulable response.

Complications Associated with Pulmonary Artery Catheters: A Comprehensive Clinical Review

Care for the critically ill patient requires maintenance of adequate tissue perfusion/oxygenation. Continuous hemodynamic monitoring is frequently utilized to achieve these objectives. Pulmonary artery catheters (PAC) allow measurement of hemodynamic variables that cannot be measured reliably or continuously by less invasive means. Inherent to every medical intervention are risks associated with that intervention. This review categorizes complications associated with the PAC into four broad groups — Complications of central venous access; complications related to PAC insertion and manipulation; complications associated with short- or long-term presence of the PAC in the cardiovascular system; and errors resulting from incorrect interpretation/use of PAC-derived data. We will discuss each of these four broad categories, followed by in-depth descriptions of the most common and most serious individual complications.

Heparin-bonded catheters for prolonging the patency of central venous catheters in children

BACKGROUND

Central venous catheters (CVCs) are a mainstay in the management of critically ill children. However, these catheters are associated with mechanical and infectious complications which reduce their life span. Heparin bonding of catheters has shown promise in animal studies and in adults.

OBJECTIVES

The primary objective was to determine the effect of heparin-bonded CVCs on the duration of catheter patency in children. Secondary objectives were to determine the effect of heparin-bonded catheters on catheter related thrombosis, occlusion, sepsis and side effects.

SEARCH STRATEGY

We searched the Cochrane Peripheral Vascular Diseases (PVD) Group Trials Register (inception to August 2007) which contains trials identified through searches of MEDLINE (1966 to August 2007), EMBASE (1980 to August 2007), CINAHL (1982 to August 2007), and hand searches along with the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2007, Issue 3.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials of heparin-bonded catheters versus non-heparin bonded catheters or antibiotic-impregnated catheters that reported on any of the prespecified outcomes, without language restriction.

DATA COLLECTION AND ANALYSIS

Methodological quality of the trials was assessed using the information provided in the studies and by contacting authors. Data were extracted and the effect size was estimated and reported as relative risk (RR), risk difference (RD) or number needed to treat (NNT), as appropriate.

MAIN RESULTS

Two eligible studies reflecting 287 patients were included; both had good methodological quality. There was no difference in the duration of catheter patency between heparin bonded and non-heparin bonded catheters (median duration 7 days vs 6 days) reported in one study. There was no difference in the risk of catheter related thrombosis (RR 0.71, 95% CI 0.44 to 1.15; RD -0.05, 95% CI 0.13 to 0.02; I(2) = 79%). Data from one study revealed a statistically significant reduction in the risk of catheter occlusion (RR 0.06, 95% CI 0.00 to 1.07; RD -0.08, 95% CI -0.13 to -0.02; NNT 13, 95% CI 8 to 50), catheter-related infections (RR 0.06, 95% CI 0.01 to 0.41; RD -0.17, 95% CI -0.25 to -0.10; NNT 6, 95% CI 4 to 10) and catheter colonization (RR 0.21, 95% CI 0.06 to 0.71; RD -0.11, 95% CI -0.19 to -0.04; NNT 9, 95% CI 5 to 25) in the heparin-bonded catheter group.

AUTHORS' CONCLUSIONS

Two eligible studies on the use of heparin-bonded catheters versus placebo in children were identified. The use of heparin-bonded catheters is a promising therapy but warrants further studies.

Improving the accuracy of impedance cardiac output in the intensive care unit: comparison with thermodilution cardiac output

This study examined the effect of impedance algorithm adjustment to reflect abnormalities found in cardiac output estimation in the intensive care unit. Impedance (Kubicek and Sramek equations) and thermodilution were measured concurrently in 61 patients. The mean difference between Kubicek and thermodilution (n=40) was 1.47 L/min (95% confidence interval [CI], 0.47-2.47) and between Sramek and thermodilution (n=54) was 2.68 L/min (95% CI, 1.93-3.44). Exclusion of patients with valve regurgitation improved agreement between Kubicek and thermodilution (n=32), with a mean difference of 2.02 L/min (95% CI, 1.10-2.94). Multiple regression determined the role of skinfold thickness, pH, hematocrit, sodium, chloride, albumin, protein, and urea within impedance. Kubicek was recalculated using the new algorithm and recompared with thermodilution. The mean difference was -0.38 L/min (95% CI, -1.92 to 1.16). This study found poor agreement between impedance and thermodilution in critically ill patients, but exclusion of those with valve regurgitation and adjustment for hematocrit and skinfold thickness improved agreement.

Cardiovascular collapse due to massive pulmonary thromboembolism during orthotopic liver transplantation

Severe pulmonary thromboembolism has been occasionally reported during orthotopic liver transplantation, with fatal outcomes occurring in about 50% of cases because of low cardiac output and multiple organ failure. Perioperative alterations in coagulation, insertion of pulmonary artery and other invasive catheters, administration of antifibrinolytic agents, and repeated ischemic insults may all promote the formation of intravascular/cardiac blood clots. We present a case of intraoperative right ventricular failure associated with the presence of a large thrombus wrapped around the pulmonary artery catheter. Identification of risk factors for intraoperative pulmonary thromboembolism warrants a prophylactic medical approach including selective blood component therapy and administration of antifibrinolytics guided by bedside coagulation tests as well as noninvasive hemodynamic monitoring.

Systemic coagulation changes caused by pulmonary artery catheters: laboratory findings and clinical correlation

BACKGROUND

A higher rate of pulmonary embolism has been associated with pulmonary artery (PA) catheters; however, no mechanism has been described. Conventional tests of coagulation reveal no changes related to PA catheterization. The purpose of this study was to determine whether PA catheterization resulted in a hypercoagulable state detectable by thrombelastography (TEG).

METHODS

ANIMAL

Healthy, anesthetized, swine (n = 19) underwent PA catheterization. Samples were drawn from 7F femoral arterial catheters before and two hours after PA catheterization, at 5 mL/min, and analyzed (native whole blood, n = 15, kaolin activated blood, n = 4) by TEG (Hemoscope, Niles, IL) at precisely two minutes. Human: An IRB-approved prospective, observational trial was conducted in critically ill patients (n = 19). Samples were drawn from 22-gauge radial artery catheters, before and three hours after PA catheterization. Kaolin-activated TEG samples were analyzed at precisely five minutes. Data are mean +/- SE; Groups were compared with analysis of variance and significance was assessed at the 95% confidence interval.

RESULTS

In both animals and patients, PA catheterization truncated R times (time to initial fibrin formation). In swine, the R times were 17.6 +/- 1.3 minutes (native) and 3.8 +/- 0.4 (kaolin) before PA catheterization, and decreased to 6.3 +/- 1.0 minutes (p = 0.002) and 1.9 +/- 0.5 minutes (p = 0.010) afterward. There were no changes in pH or temperature during the experiment. In patients, 4 of 19 were excluded for protocol violations. The R time was 6.3 +/- 1.0 minutes (kaolin) before and 3.0 +/- 0.3 minutes after catheterization (p = 0.003). No changes were observed in conventional coagulation parameters, temperature or pH.

CONCLUSION

In healthy swine, and critically ill patients, PA catheters may enhance thrombin formation and fibrin polymerization, indicating a systemic hypercoagulable state. This may explain why PA catheters are associated with an increased risk of pulmonary emboli.

Complications of invasive monitoring

Invasive monitoring in anesthesiology is relatively safe. Arterial catheterization in particular has an extremely low rate of serious complications. Radial, brachial, and femoral artery catheterization sites appear to have similar and low complication rates. CVP and PA catheters are more dangerous and entail potentially fatal complications. The most troublesome complication with CVP catheters is perforation of the heart or cava, which should be avoidable under most circumstances if care is taken to position the catheter properly, outside the heart. Chest radiography should be used to specifically ascertain that the catheter is not in a dangerous location. The most troublesome complication with PA catheters is perforation of the pulmonary artery. This is probably a sporadic problem, and it is not necessarily avoidable by adherence to particular techniques. It should be assumed that hemoptysis in a patient with a PA catheter is caused by perforation of the pulmonary artery until proven otherwise, and it should be treated aggressively.

A scanning electron microscopic study on thrombogenicity of intraarterial catheters for chemotherapeutic treatment in head and neck cancer

BACKGROUND

The purpose of this study was to assess the impact of standard anticoagulation and intermittent catheter irrigation on clot formation on intraarterial chemotherapeutical catheters.

METHODS

Sixteen nonheparinized catheters were placed in the carotid vessels of 10 patients. Ten catheters were perfused with chemotherapeutic drugs; six catheters were not perfused. Patients received LMWH anticoagulation; catheters were irrigated with boluses of heparinized saline daily. Catheters were retrieved for SEM evaluation after a mean intravessel placement interval of 21 days.

RESULTS

All samples demonstrated accumulation of thrombotic debris on luminal sides and outsides of catheters. Obliteration was seen in three samples. Detachment of thrombus fragments was present in several specimens. No significant dependence of clot formation on placement interval and chemotherapeutic perfusion was calculated.

CONCLUSIONS

Standard anticoagulation was ineffective in clot prevention. Heparinized catheters might potentially reduce the risk of clot formation. A delivery system should be engaged for continuous irrigation of catheters with heparinized saline.