Short and medium-term impact of a cardiac rehabilitation (CR) program in COVID-19 patients after acute care hospitalization

Background

COVID-19 (C-19) infection can acutely cause organ dysfunctions, especially cardiorespiratory, even with a long recovery period, inducing a significant functional deficit. Aim of the study was to evaluate the impact of a holistic hospital intensive rehabilitation program, based on CR, on C-19 patients (P), after acute care, to improve their fitness, in order to return to their life in the best conditions.

Methods

In the period april-august 2020, 30 P (mean age 73 years, 60% male) were admitted to the rehabilitation centre at a mean distance of 31±11 days from the onset of C-19; 34% of them had undergone prolonged invasive ventilation, 34% non invasive ventilation and 32% required high flow oxygen. Comorbidities were: hypertension (77%), diabetes (13%) and chronic coronary syndrome (10%); 18 P were unable to stand, and 12 showed impaired trunk control. No P had impaired LVEF or significant valvular disease. Initially, the program focused on training for trunk and sitting control; then on exercises for straightening the upper and lower limbs. From the second week, started a CR training on the cycle ergometer 10–20 minutes a day for 6 days a week, similar protocol to that used in P with heart failure. The aerobic training was of moderate intensity, not exceeding 40–60% of the maximum heart rate, Borg scale 10–12, starting with zero load, gradually increasing by 10–15 watts and up to a minimum target of 25–30 watts. The impact of the protocol on motor functions [MRC Muscle Strenght Scale, Short Physical Performance Battery (SPPB)] on functional capacity [6 Minutes Walking Test (6MWT)] on anxiety (A) and depression (D) [Hamilton Anxiety Rating scale (HAMA) and Hamilton Depression Rating scale (HAMD)] and on basic activities of daily life [Barthel Index (BI)] were evaluated. The assessment was done on the admission (T0), at the discharge (T1, on average after 31 days) and after a follow-up of 55 days (T3).

Results

The results are shown in the table below. Only 4 P were able to perform the 6MWT at T0. The motor function improves rapidly and then reaches a plateau and its trend is reflected in the BI. Functional capacity, on the other hand, improves significantly even at a distance. A and D decreased rapidly but increased over time.

Conclusions

A rehabilitation protocol, centered on CR, induces a rapid increase in motor capacity, even in severely compromised subjects such as C-19. The improvement in fitness over time, as demonstrated by the 6MWT, probably is due to the severe muscle deconditioning, for the long stay in acute care. The long-term worsening of A and D may depend on various causes: no longer living in a “protected and safe” place, the fear of relapse, returning home and discovering new deaths and mournings. A program, CR-like, can counteract many of the negative consequences of C-19; however these P deserve an outpatient rehabilitation to maintain and consolidate the positive results over time.

Funding Acknowledgement

Type of funding sources: None. Table 1

Comparison between the 6-minute walking test (6MWT) and gait speed (GS) during outpatient cardiac rehabilitation

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): USL TOSCANA CENTRO USL TOSCANA NORD-OVEST

Background

6MWT is the gold standard for the functional and prognostic evaluation of patients (P) undergoing cardiac rehabilitation (CR), documenting the increase in exercise capacity induced by CR intervention. However, 6MWT requires an adequate space of at least 30 meters and a non-negligible operator time. GS has been proposed as a test of rapid execution, that can be performed even in a small space. Due to the limited experiences, the aim of the present study was to validate GS in CR in comparison with 6MWT.

Material and Methods

44 P (31 males and 13 females; age 68.2 ± 11.9 years) were enrolled consecutively in an outpatient rehabilitation program; 20 of them after cardiac surgery, 18 after acute cardiac syndrome and 6 with heart failure. After evaluating equilibrium and gait with the Tinetti scale (score ≥ 19), P performed 6MWT and GS at the beginning and at the end of the CR program. The speed at GS was calculated as the average of 3 tests. Data were expressed as mean ± SD. The results of 6MWT and GS at the initial and the final evaluation were compared with Student’s t-test for paired data (statistical significance at p <0.05). The Pearson correlation index (r) was calculated to evaluate the linearity relationship between distance traveled at 6MWT and velocity at GS; the  statistical significance was tested with ANOVA. The Statistical Package SPSS (version 24) was used for statistical analysis.

Results

the meters traveled at the initial and the final 6MWT were 434 ± 100 and 491 ± 96 respectively (p <0.001). The velocity in m/sec at the initial and the final GS was 1.68 ± 0.42 and 1.80 ± 0.44 respectively (p <0.001). The correlation between meters traveled and velocity is strong at baseline (r = 0.896) and after CR (r = 0.859), with p <0.001 in both cases.

Conclusions

certainly, aerobic capacity and resistance to exercise are better described by 6MWT. However, given the strong correlation between the distance traveled at 6MWT and the speed at GS, the latter test can be proposed as a tool for a rapid, precise and repeatable functional evaluation, even in clinical settings other than CR.

Endogenous surfactant turnover in preterm infants with respiratory distress syndrome studied with stable isotope lipids

We studied surfactant kinetics on Day 1 of life in 11 preterm infants on mechanical ventilation by infusing stable isotope labeled palmitic (PA) and linoleic acid (LLA). Six infants received exogenous surfactant for the treatment of respiratory distress syndrome (RDS) and five did not meet treatment criteria because of minimal or no disease. The isotopic enrichment of plasma free PA and LLA and of surfactant phosphatidylcholine PA (PC-PA) and LLA (PC-LLA) from tracheal aspirates was measured by mass spectrometry. Significant isotopic enrichment could be measured in PC-PA and PC-LLA from all patients. The fractional synthesis rate (FSR) of PC-LLA was higher than that of PC-PA (22.7 +/- 15.9 versus 12.1 +/- 7.7% per day, p = 0.018). Half-life (HL) of PC-PA was longer than that of PC-LLA (94.7 +/- 18.8 versus 46.6 +/- 32.6 h, p = 0.028). Patients who received exogenous surfactant had longer secretion times (ST) and delayed peak times (PK) but FSR and HL were unaffected. We concluded that: (1) surfactant kinetics can be measured in preterm infants with stable isotope labeled lipids; (2) surfactant FSR and HL calculated with PA and LLA gave different results; (3) patients treated with exogenous surfactant had similar FSRs compared with the nontreated subjects but had longer ST and delayed PK; (4) FSR from plasma free fatty acids (present study) was higher than that from plasma glucose in our previous work (Bunt JEH, Zimmermann LJI, Wattimena D, van Beek R, Sauer PJJ, Carnielli VP. Am J Respir Crit Care Med 1998;157:810-814) in a comparable population of preterm infants with RDS.

Exogenous surfactant kinetics in infant respiratory distress syndrome: A novel method with stable isotopes

Little is known about surfactant metabolism in newborn infants, since radioactive isotopes cannot be used in humans. We describe here a new method for studying exogenous surfactant pharmacokinetics in vivo. We measured surfactant half-life, pool size, and turnover time in eight preterm infants (gestational age: 30 +/- 2 wk; birth weight: 1,416 +/- 202 g) who were mechanically ventilated because of infant respiratory distress syndrome. We administered two doses of 100 mg/kg each of a natural porcine surfactant with (13)C-labeled dipalmitoylphosphatidylcholine as a tracer. The (13)C enrichment of surfactant disaturated phosphatidylcholine (DSPC) was measured in serial tracheal aspirates by gas chromatography-mass spectrometry. The DSPC half-life was 34.2 +/- 9.4 h (mean +/- SD; range: 21.8 to 45.9 h). The apparent DSPC pool sizes were 5.8 +/- 6.1 mg/kg (range: 0.1 to 17.0 mg/kg) and 17.3 +/- 13.6 mg/kg (range: 3.3 to 41.0 mg/kg) at the time of the first and second surfactant doses, respectively. We present a novel and safe method that allows the tracing of exogenous surfactant phosphatidylcholine, the major lipid component of pulmonary surfactant, in infants who receive exogenous surfactant. This method could be a valuable tool for studying: (1) therapies that enhance lung/surfactant maturation; (2) the dosing and timing of surfactant therapy in different lung diseases; and (3) the comparison of different surfactant preparations.