Inhaled Epoprostenol Compared With Nitric Oxide for Right Ventricular Support After Major Cardiac Surgery

BACKGROUND

Right ventricular failure (RVF) is a leading driver of morbidity and death after major cardiac surgery for advanced heart failure, including orthotopic heart transplantation and left ventricular assist device implantation. Inhaled pulmonary-selective vasodilators, such as inhaled epoprostenol (iEPO) and nitric oxide (iNO), are essential therapeutics for the prevention and medical management of postoperative RVF. However, there is limited evidence from clinical trials to guide agent selection despite the significant cost considerations of iNO therapy.

METHODS

In this double-blind trial, participants were stratified by assigned surgery and key preoperative prognostic features, then randomized to continuously receive either iEPO or iNO beginning at the time of separation from cardiopulmonary bypass with the continuation of treatment into the intensive care unit stay. The primary outcome was the composite RVF rate after both operations, defined after transplantation by the initiation of mechanical circulatory support for isolated RVF, and defined after left ventricular assist device implantation by moderate or severe right heart failure according to criteria from the Interagency Registry for Mechanically Assisted Circulatory Support. An equivalence margin of 15 percentage points was prespecified for between-group RVF risk difference. Secondary postoperative outcomes were assessed for treatment differences and included: mechanical ventilation duration; hospital and intensive care unit length of stay during the index hospitalization; acute kidney injury development including renal replacement therapy initiation; and death at 30 days, 90 days, and 1 year after surgery.

RESULTS

Of 231 randomized participants who met eligibility at the time of surgery, 120 received iEPO, and 111 received iNO. Primary outcome occurred in 30 participants (25.0%) in the iEPO group and 25 participants (22.5%) in the iNO group, for a risk difference of 2.5 percentage points (two one-sided test 90% CI, -6.6% to 11.6%) in support of equivalence. There were no significant between-group differences for any of the measured postoperative secondary outcomes.

CONCLUSIONS

Among patients undergoing major cardiac surgery for advanced heart failure, inhaled pulmonary-selective vasodilator treatment using iEPO was associated with similar risks for RVF development and development of other postoperative secondary outcomes compared with treatment using iNO.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03081052.

Analysis of radial artery catheter placement by respiratory therapists using ultrasound guidance

BACKGROUND

The use of ultrasound (US) guidance for radial artery cannulation has been shown to improve first attempt success rate, reduce time to successful cannulation, and reduce complications. We sought to determine whether properly trained respiratory therapists (RTs) could utilize US guidance for the placement of radial artery catheters. Primary outcome measurements were successful cannulation and first attempt success rate. Secondary outcomes included the effect of systolic blood pressure, prior attempts, palpable pulse strength, and gender in relation to US-guided radial artery cannulation success rates.

METHODS

RTs certified in arterial catheter insertion were trained in radial artery catheterization using US by emergency medicine physicians. Subjects were enrolled based on the need for an arterial catheter placement. The catheters and US devices used were standardized. Data recorded included pulse strength, systolic and diastolic blood pressure, number of attempts, and successful/unsuccessful artery cannulation. All catheterization attempts were performed according to institutional policy and procedure.

RESULTS

One hundred twenty-two radial artery catheter insertion attempts were made between December of 2008 and October of 2011, in patients in whom the treating physician requested RT radial artery cannulation. The overall success rate was 86.1%, whereas the first attempt success rate was 63.1%. There was no difference found between the overall mean success rate for weak or absent pulses, age, systolic blood pressure, gender, or prior attempts.

CONCLUSION

RTs can effectively utilize US technology to place radial artery catheters. Systolic blood pressure, prior attempts, and gender are not reliable predictors of success for US-guided radial artery cannulation. Training on the use of US should be strongly encouraged for all practitioners who place radial artery catheters.

Noninvasive ventilation in severe acute asthma

Noninvasive ventilation (NIV) in severe acute asthma is controversial but may benefit this population by preventing intubation. We report on a 35-year-old male asthma patient who presented to our emergency department via emergency medical services. The patient was responsive, diaphoretic, and breathing at 35 breaths/min on 100% oxygen with bag-mask assistance, with S(pO2) 88%, heart rate 110-120 beats/min, blood pressure 220/110 mm Hg, and temperature 35.8 °C. NIV at 12/5 cm H2O and FIO2 0.40 was applied, and albuterol at 40 mg/h was initiated. Admission arterial blood gas revealed a pH of 6.95, P(aCO2) 126 mm Hg, and P(aO2) 316 mm Hg. After 90 min of therapy, P(aCO2) was 63 mm Hg. Improvement continued, and NIV was stopped 4 h following presentation. NIV tolerance was supported with low doses of lorazepam. The patient was transferred to the ICU, moved to general care the next morning, and discharged 3 days later. We attribute our success to close monitoring in a critical care setting and the titration of lorazepam.