The Compensatory Reserve Index Responds to Acute Hemodynamic Changes in Patients with Congenital Heart Disease: A Proof of Concept Study.

Patients with congenital heart disease (CHD) who undergo cardiac procedures may become hemodynamically unstable. Predictive algorithms that utilize dense physiologic data may be useful. The compensatory reserve index (CRI) trends beat-to-beat progression from normovolemia (CRI = 1) to decompensation (CRI = 0) in hemorrhagic shock by continuously analyzing unique sets of features in the changing pulse photoplethysmogram (PPG) waveform. We sought to understand if the CRI accurately reflects changing hemodynamics during and after a cardiac procedure for patients with CHD. A transcatheter pulmonary valve replacement (TcPVR) model was used because left ventricular stroke volume decreases upon sizing balloon occlusion of the right ventricular outflow tract (RVOT) and increases after successful valve placement. A single-center, prospective cohort study was performed. The CRI was continuously measured to determine the change in CRI before and after RVOT occlusion and successful TcPVR. Twenty-six subjects were enrolled with a median age of 19 (interquartile range (IQR) 13-29) years. The mean (± standard deviation) CRI decreased from 0.66 ± 0.15 1-min before balloon inflation to 0.53 ± 0.16 (p = 0.03) 1-min after balloon deflation. The mean CRI increased from a pre-valve mean CRI of 0.63 [95% confidence interval (CI) 0.56-0.70] to 0.77 (95% CI 0.71-0.83) after successful TcPVR. In this study, the CRI accurately reflected acute hemodynamic changes associated with TcPVR. Further research is justified to determine if the CRI can be useful as an early warning tool in patients with CHD at risk for decompensation during and after cardiac procedures.

Lessons Learned From the First Pilot Study of the Compensatory Reserve Index After Congenital Heart Surgery Requiring Cardiopulmonary Bypass.

BACKGROUND: Early warning systems that utilize dense physiologic data and machine learning may aid prediction of decompensation after congenital heart surgery (CHS). The Compensatory Reserve Index (CRI) analyzes changing features of the pulse waveform to predict hemodynamic decompensation in adults, but it has never been studied after CHS. This study sought to understand the feasibility, safety, and potential utility of CRI monitoring after CHS with cardiopulmonary bypass (CPB). METHODS: A single-center prospective pilot cohort of patients undergoing pulmonary valve replacement was studied. Compensatory Reserve Index was continuously measured from preoperative baseline through the first 24 postoperative hours. Average CRI values during selected procedural phases were compared between patients with an intensive care unit (ICU) length of stay (LOS) <3 days versus LOS ≥3 days. RESULTS: Twenty-three patients were enrolled. On average, 17,445 (±3,152) CRI data points were collected and 0.33% (±0.40) of data were missing per patient. There were no adverse events related to monitoring. Five (21.7%) patients had an ICU LOS ≥3 days. Compared to the ICU LOS <3 days group, the ICU LOS ≥3 days group had a greater decrease in CRI from baseline to immediately after CPB (-0.3 ± 0.1 vs -0.1 ± 0.2, P = .003) and were less likely to recover to baseline CRI during the monitoring period (20% vs 83%, P = .017). CONCLUSIONS: Compensatory Reserve Index monitoring after CHS with CPB seems feasible and safe. Early changes in CRI may precede meaningful clinical outcomes, but this requires further study.

Low postnatal CRI values are associated with the need for ECMO in newborns with CDH.

INTRODUCTION: Accurate, real-time technology is needed to predict which newborns with congenital diaphragmatic hernia (CDH) will require ECMO. The Compensatory Reserve Index (CRI) is a noninvasive monitoring technology that continuously trends an individual's capacity to compensate from normovolemia (CRI = 1) to decompensation (CRI = 0). We hypothesized that postnatal CRI values would be lower in CDH newborns that required ECMO than those who did not require ECMO. METHODS: Newborns with a CDH were prospectively monitored with a CipherOx® CRI M1 device. We compared CRI values from delivery to ECMO (ECMO group) versus delivery to clinical stabilization (non-ECMO group). RESULTS: Postnatal CRI values were available from 26 newborns. Eight underwent ECMO within 33 h of delivery, and median CRI prior to ECMO was 0.068 (IQR: 0.057, 0.078). Eighteen did not require ECMO. Median CRI from birth to 48 h was 0.112 (IQR: 0.082, 0.15). CRI values were significantly lower in newborns that required ECMO versus those who did not (p = 0.0035). Postnatal CRI had the highest AUC (0.85) compared to other prenatal prognostic measures. CONCLUSION: Humans from newborns to adults share elemental features of the pulsatile waveform that are associated with progression to decompensation. CRI may be helpful when deciding when to initiate ECMO. LEVEL OF EVIDENCE: Level III. TYPE OF STUDY: Diagnostic test.

Acute appendicitis: a disease severity score for the acute care surgeon.

BACKGROUND: Analogous to organ injury scales developed for trauma, a scoring system is needed for acute care surgery. The purpose of this study was to develop a disease severity score (DSS) for acute appendicitis, the most common surgical emergency. METHODS: A panel of acute care surgery experts reviewed the literature and developed a DSS for acute appendicitis as follows: grade 1, inflamed; Grade 2, gangrenous; Grade 3, perforated with localized free fluid; Grade 4, perforated with a regional abscess; and Grade 5, perforated with diffuse peritonitis. We applied the DSS to 1,000 consecutive patients undergoing appendectomy from 1999 to 2009 and examined its association with outcomes (mortality, length of hospital stay, incidence of in-hospital, and postdischarge complications). Of the 1,000 patients, 82 were excluded owing to negative or interval appendectomy or advanced end-stage renal disease. RESULTS: Among 918 eligible patients, the DSS distribution was Grade 1 at 62.4%, Grade 2 at 13.0%, Grade 3 at 18.7%, Grade 4 at 4.4%, and Grade 5 at 1.5%. Statistical analyses indicated a stepwise risk increase in adverse outcomes with higher DSS grades (c statistics ≥ 0.75 for all outcomes). Covariates (age, sex, and type of surgical access) did not add to the predictive power of DSS. CONCLUSION: Based on this single-institution study, the proposed appendicitis DSS seems to be a useful tool. This DSS can inform future, national efforts, which can build on the knowledge provided by the present investigation. This DSS may be useful for comparing therapeutic modalities, planning resource use, improving programs, and adjusting reimbursement LEVEL OF EVIDENCE: Epidemiologic study, level III.