Malposition of extracorporeal membrane oxygenation cannulas in patients with congenital diaphragmatic hernia

Point-of-care ultrasound for the evaluation of venous cannula position in neonatal extracorporeal membrane oxygenation

OBJECTIVE

To assess the ability of point-of-care ultrasound (POCUS) to identify venous cannula position in neonates on extracorporeal membrane oxygenation (ECMO) and compare with conventional imaging.

STUDY DESIGN

Retrospective review of 37 infants on ECMO with 51 POCUS studies between January 2017 and October 2019. Studies were reviewed for identification of venous cannula location and compared with plain radiography and echocardiography. Kappa statistic and predictive values were calculated.

RESULTS

Venous cannula tip position was identified in 90% of POCUS studies. Fifty percent of the cannula tips were malpositioned. Plain radiography, the most commonly used method for evaluating tip position, showed poor agreement (57%) with POCUS (kappa 0.13). There was substantial agreement (89%) between echocardiography and POCUS (kappa 0.78).

CONCLUSION

This study provides preliminary evidence that POCUS is more accurate than plain radiography for the evaluation of ECMO venous cannula position. Adoption of this practice may prevent potentially catastrophic ECMO complications.

Intraoperative ultrasound reduces ECMO catheter malposition requiring surgical correction

BACKGROUND/PURPOSE

One hundred ninety-three cannulation procedures for extracorporeal membrane oxygenation (ECMO) have been performed at the authors' institution from 1994 to now. Before 1996, their practice had been to position these catheters exclusively by clinical assessment and chest radiograph. Since then, the authors have utilized intraoperative ultrasound guidance during cannulation procedures to confirm proper tip position. This retrospective analysis was undertaken to establish whether this practice has reduced the rate of surgical repositioning of ECMO catheters in these patients.

METHODS

A retrospective chart review was performed for all infants who underwent ECMO cannulation procedures at the authors' institution. Numbers of infants requiring surgery to readjust ECMO catheter position were totaled. Cases were categorized according to the presence or absence of intraoperative ultrasound scan. Statistical significance was determined using X(2) analysis, Student's t test, or analysis of variance where appropriate.

RESULTS

There were 193 ECMO cannulations performed. Of the 101 procedures done without ultrasound scan, 18 necessitated surgical repositioning. In contrast, only 3 of the 92 catheters placed with ultrasound assistance required reoperation. This represents a reduction the rate of repositioning from 17.8% to 3.3% of cannulations (P =.003).

CONCLUSIONS

Based on these findings, the authors advocate the use of intraoperative ultrasound imaging to optimize the position of ECMO catheters. This high rate of initial success helps avoid the potential morbidity of ECMO circuit malfunction, repeat neck dissection, and catheter manipulation in these critically ill, anticoagulated patients.

Cervical ECMO cannula placement in infants and children: recommendations for assessment of adequate positioning and function

BACKGROUND/PURPOSE

Cervical extracorporeal membrane oxygenation (ECMO) cannula position is often difficult to confirm by chest x-ray alone. Malposition requires a second surgery to rectify the problem. Reoperation places the patient at risk for infection, bleeding, or death. This study analyzes indications for cannula repositioning and suggests an alternative standard for intraoperative evaluation of catheter function as it relates to position.

METHODS

The authors reviewed charts of 73 patients placed on arterio-venous ECMO through cervical vascular access. Reasons for repositioning of either cannula at the initial surgery or postoperatively were recorded.

RESULTS

Of 73 patients, 18 (24.6%) required either arterial cannula or venous cannula repositioning. In 10 (55%) of these patients, cannula malposition was not detected by chest x-ray during the initial cannulation, and they therefore required a second cervical exploration for repositioning.

CONCLUSIONS

Chest x-ray is not sensitive in demonstrating malpositioned cervical ECMO cannulae. Two-dimensional ECHO before wound closure, may be a superior, more cost effective means of assessing cannula placement and function than x-ray alone. Confirmation of cannula position and function, before wound closure, would reduce the risks involved with cervical reexploration.

Complications of neonatal extracorporeal membrane oxygenation

From 1973-1985 to 1988 the average patient complications per case were 1.44 per case and significantly increased during 1990 to 1992 to 2.10 per case (Figure 3). During the same periods patient survival significantly decreased from 84% (1973-1985 to 1988, n = 2463) to 80% (1990 to 1992, n = 4005) (Figure 4). The association between total complication rates and survival rate was examined by regression analysis (Table 5). The correlation of patient complication rate and total complication rate with survival is highly significant; however, causality cannot be established. When comparing different entry criteria (Table 2) for incidence of mechanical and patient complications, no significant differences are apparent. This is not surprising since each of the entry criteria were designed to identify the same patient population. When premature neonates (> 35 weeks) were placed on ECMO, 36% of them had intracranial haemorrhage (ICH) with 62% mortality while only 12% of the neonates < 35 weeks had ICH and a 49% mortality. Similar findings were noted with low birthweight neonates (< 2.2 kg), 28% had ICH with 64% mortality while only 12% of the neonates > 2.2 kg had ICH with a 50% mortality. Selection criteria remain problematic for a variety of reasons. They cannot be viewed as absolute because of variability between centres. What represents likely 80% mortality in one centre may not apply to another. Historical controls are misleading because changing respiratory therapy strategies make historical populations difficult to compare. Also, once an ECMO centre becomes established, a more challenging group of patients will be attracted than previously was the case. Further, a single entry criterion cannot be generalized for all entry diagnoses. Criteria for an 80% predicted mortality is probably not the same for MAS, CHN, PPHN, and sepsis. Subsequent patients registered in the Neonatal ECMO Registry of the Extracorporeal Life Support Organization will address these issues more thoroughly, as specific details of the pre-ECMO condition and therapeutic strategies are collected. This collective review should help to identify trends which require reassessment of technique or patient management.