Post-COVID-19 recovery and geriatric rehabilitation care: a European inter-country comparative study.

PURPOSE: There is variation in organization of geriatric rehabilitation across Europe. The purpose of this study was to describe the selection criteria for referral to geriatric rehabilitation, care provided, and recovery trajectories of post-COVID-19 patients referred to geriatric rehabilitation in Europe. METHODS: This observational cohort study included 723 patients in 59 care facilities for geriatric rehabilitation across 10 countries. Patient data were collected from medical records on admission to geriatric rehabilitation (between September 2020 and October 2021), discharge, 6 weeks and 6 months follow-up. The primary and secondary outcomes were recovery in daily functioning (Barthel Index) and Quality of Life (EQ-5D-5L) from admission to discharge. These were examined using linear mixed models with two levels (measurements nested in patients) and country as an independent variable. Random intercept and random linear slope parameters were added when they improved model fit. A survey about organization of geriatric rehabilitation for post-COVID-19 patients was filled out by country coordinators and data were analyzed using descriptive statistics and inductive coding of answers to open questions. RESULTS: Patients had a mean age of 75.7 years old and 52.4% were male. Many countries used various combinations of the selection criteria, such as functional status, age, frailty, Comprehensive Geriatric Assessment, comorbidities, and cognitive impairments. Most patients received physiotherapy (88.8%) and occupational therapy (69.7%), but there was substantial variance between countries in the percentages of patients that received protein or calorie enriched diets, oxygen therapy, and other treatment components. In all countries, patients showed recovery in daily functioning and quality of life, although there was variation in between countries in rate of recovery. Daily functioning seemed to increase most rapidly in the Czech Republic, Germany, and Russia. The steepest increases in quality of life were seen in the Czech Republic, Germany, and Spain. CONCLUSION: Post-COVID-19 patients showed recovery during geriatric rehabilitation, albeit at variable rates. The observed variation may be explained by the heterogeneity in selection criteria and care provided. This study highlights the need for harmonization of measurements in geriatric rehabilitation order to perform explanatory research and optimize geriatric rehabilitation throughout Europe to ensure optimal patient recovery.

Post-COVID-19 patients in geriatric rehabilitation substantially recover in daily functioning and quality of life.

BACKGROUND: After an acute infection, older persons may benefit from geriatric rehabilitation (GR). OBJECTIVES: This study describes the recovery trajectories of post-COVID-19 patients undergoing GR and explores whether frailty is associated with recovery. DESIGN: Multicentre prospective cohort study. SETTING: 59 GR facilities in 10 European countries. PARTICIPANTS: Post-COVID-19 patients admitted to GR between October 2020 and October 2021. METHODS: Patients' characteristics, daily functioning (Barthel index; BI), quality of life (QoL; EQ-5D-5L) and frailty (Clinical Frailty Scale; CFS) were collected at admission, discharge, 6 weeks and 6 months after discharge. We used linear mixed models to examine the trajectories of daily functioning and QoL. RESULTS: 723 participants were included with a mean age of 75 (SD: 9.91) years. Most participants were pre-frail to frail (median [interquartile range] CFS 6.0 [5.0-7.0]) at admission. After admission, the BI first steeply increased from 11.31 with 2.51 (SE 0.15, P < 0.001) points per month and stabilised around 17.0 (quadratic slope: -0.26, SE 0.02, P < 0.001). Similarly, EQ-5D-5L first steeply increased from 0.569 with 0.126 points per month (SE 0.008, P < 0.001) and stabilised around 0.8 (quadratic slope: -0.014, SE 0.001, P < 0.001). Functional recovery rates were independent of frailty level at admission. QoL was lower at admission for frailer participants, but increased faster, stabilising at almost equal QoL values for frail, pre-frail and fit patients. CONCLUSIONS: Post-COVID-19 patients admitted to GR showed substantial recovery in daily functioning and QoL. Frailty at GR admission was not associated with recovery and should not be a reason to exclude patients from GR.

Tetrahydrobiopterin (BH4 ): Targeting endothelial nitric oxide synthase as a potential therapy for pulmonary hypertension.

PURPOSE: Pulmonary Hypertension (PH) is complex disease which is associated with endothelial and cardiac dysfunction. Tetrahydrobiopterin (BH4 ) regulates endothelial nitric oxide synthase (eNOS) to produce nitric oxide rather than superoxide which maintains normal endothelial and cardiac function. This study explores the therapeutic potential of BH4 in experimental PH. METHODS: Monocrotaline-induced PH in rats and Hph-1 deficiency in mice were used for animal experiments. Hemodynamic measurements using pressure transducers were conducted for pulmonary and cardiac pressures, and Langendorff apparatus was used for isolated heart experiments; preventive as well as rescue treatment protocols were conducted; tissues were collected for histological and biochemical studies. RESULTS: In vivo acute BH4 administration reduced pulmonary artery pressure (PAP) only in the MCT rat. In a Langendorff preparation, BH4 increased right ventricular systolic pressure (RVSP) in right ventricular hypertrophy (RVH) but not in control. In "prevention" therapy, BH4 (10 and 100 mg/kg) attenuated the development of PH in rat MCT model. eNOS protein levels in lung homogenates were maintained and cGMP levels were increased. In "rescue" therapy, BH4 (10 and 100 mg/kg) ameliorated pulmonary vascular muscularization in a dose-dependent manner. RVSP was reduced in RVH and pulmonary vascular muscularization was attenuated. BH4 at 10 mg/kg reduced RV myocyte diameter while BH4 at 100 mg/kg reversed it to control level. BH4 restored normal levels of eNOS protein and in a dose of 100 mg/kg enhanced lung tissue levels of BH4 , cGMP, and NO compared to placebo. CONCLUSION: The current study provides scientific evidence for a therapeutic potential of BH4 in PH and invites further investigation.

Cardiac and renal distribution of ACE and ACE-2 in rats with heart failure.

Congestive heart failure is often associated with impaired kidney function. Over-activation of the renin-angiotensin-aldosterone system (RAAS) contributes to avid salt and water retention in heart failure. While the expression of angiotensin converting enzyme (ACE), a key enzyme in the synthesis of angiotensin II (Ang II), is well established, the expression of angiotensin converting enzyme-2 (ACE-2), an enzyme responsible for angiotensin 1-7 generation, is largely unknown. This issue is of a special interest since angiotensin 1-7 counteracts many of the proliferative and hypertensive effects of angiotensin II. Therefore, the present study was designed to investigate the expression of both enzymes in the kidney and heart of rats with heart failure. Heart failure (CHF) was induced in male Sprague Dawley rats (n=9) by the creation of a surgical aorto-caval fistula. Sham-operated rats served as controls (n=8). Two weeks after surgery, the animals were sacrificed and their hearts and kidneys were harvested for assessment of cardiac remodeling and ACE and ACE-2 immunoreactivity by immunohistochemical staining. ACE immunostaining was significantly increased in the kidneys (4.34 ± 0.39% vs. 2.96 ± 0.40%, P<0.05) and hearts (4.57 ± 0.54% vs. 2.19 ± 0.37%, P<0.01) of CHF rats as compared with their sham controls. In a similar manner, ACE-2 immunoreactivity was also elevated in the kidneys (4.65 ± 1.17% vs. 1.75 ± 0.29%, P<0.05) and hearts (5.48 ± 1.11% vs. 1.13 ± 0.26%, P<0.01) of CHF rats as compared with their healthy controls. This study showed that both ACE and ACE-2 are overexpressed in the cardiac and renal tissues of animals with heart failure as compared with their sham controls. The increased expression of the beneficial ACE-2 in heart failure may serve as a compensatory response to the over-activity of the deleterious isoform, namely, angiotensin converting enzyme 1(ACE-1).

Effects of tetrahydrobiopterin oral treatment in hypoxia-induced pulmonary hypertension in rat.

Endothelial nitric oxide synthase (eNOS) plays a major role in maintaining pulmonary vascular homeostasis. Tetrahydrobiopterin (BH4), an essential cofactor that stabilizes the dimerization of eNOS and balances nitric oxide (NO) and superoxide production, may have therapeutic potential in pulmonary hypertension. In the isolated perfused lung, we demonstrated a direct effect of exogenous administration of BH4 on pulmonary NO production, leading to acute vasorelaxation during the plateau phase of hypoxia-induced pulmonary vasoconstriction. In the chronic hypoxia-induced pulmonary hypertension rat model, chronic BH4 oral administration attenuated the pressor response to hypoxia (mean pulmonary artery pressure ± standard error of the mean, 31.8 ± 0.5 mmHg at 100 mg/kg/day; placebo group, 36.3 ± 0.6 mmHg; P < 0.05). During telemetric monitoring, right ventricular systolic pressure was reduced by approximately 50% after 1 week of BH4 treatment at 100 mg/kg/day. BH4 at 100 mg/kg/day reduced right ventricular hypertrophy (from 0.55 ± 0.01 to 0.50 ± 0.01; P < 0.05) and pulmonary vascular muscularization (from 79.2% ± 2% to 65.2% ± 3%; P < 0.01). BH4 treatment enhanced lung eNOS activity and reduced superoxide production, with a net increase in cyclic guanosine monophosphate levels. BH4 is effective in attenuating pulmonary hypertension in the hypoxic rat model when given as a rescue therapy.

Effects of endothelin-1 on systemic and renal hemodynamics in hypertensive-diabetic rats (CRDH), diabetic rats (CDR), and hypertensive rats (SHR).

The Cohen-Rosenthal diabetic hypertensive rat is a unique animal model in which genetic hypertension and diabetes developed after crossbreeding of a sensitive substrain of Cohen diabetic rats and spontaneously hypertensive rats (SHR) and feeding them a copper-poor sucrose diet. This study examined the acute effects of endothelin-1 on the systemic and renal hemodynamics in Cohen-Rosenthal diabetic hypertensive rats, Cohen diabetic rats and spontaneously hypertensive rats. Intravenous injection of endothelin- 1 (1.0 nmol/kg) into anesthetized SHR resulted in a significant immediate depressor response in mean arterial pressure [from 165 +/- 3 mmHg to 124 +/- 12 mmHg (P < 0.0001)] followed by a minor hypertensive phase (mean arterial pressure increased to 170 +/- 2 mmHg). Simultaneously, the administration of endothelin-1 caused a significant decrease in renal blood flow from 5.8 +/- 0.9 mL/minute to 3.2 +/- 0.5 mL/minute (P = 0.026). These responses were blunted in Cohen-Rosenthal diabetic hypertensive rats and Cohen diabetic rats. Analysis of intrarenal blood flow by laser-Doppler in Cohen-Rosenthal diabetic hypertensive rats revealed that endothelin-1 injection caused a decrease in cortical blood flow (Delta = -12 +/- 2.9%). However, in contrast to its well known renal medullary vasodilatory effect, endothelin-1 produced a significant decline in the medulla blood flow (Delta = -17.5 +/- 3.4%) (P = 0.0125). These findings suggest that Cohen diabetic rats and Cohen-Rosenthal diabetic hypertensive rats have reduced sensitivity to the vascular and renal action of endothelin-1. Furthermore, in the Cohen-Rosenthal diabetic hypertensive rats the expected endothelin- 1-induced medullary vasodilation was abolished and even reversed into prolonged vasoconstrictor response.

Differential regulation of ET(A) and ET(B) in the renal tissue of rats with compensated and decompensated heart failure.

Endothelin-1 (ET-1) exerts its biological actions through two receptor subtypes: endothelin-A (ETA) receptor and endothelin-B (ETB) receptor. We demonstrated previously that ET-1 induces systemic and renal cortical vasoconstriction via ETA whereas ETB mediates medullary vasodilation. Congestive heart failure (CHF) is characterized by increased vascular resistance and impaired renal hemodynamic and excretory function. While the pathophysiological effects of ET-1 in CHF are well established, the status of ETA and ETB in the kidney is poorly characterized. The present study examined the immunostaining and localization of ETA and ETB in the renal cortex and medulla of rats with experimental CHF induced by aorto-caval fistula. Rats with CHF were further subdivided, based on their daily urinary sodium excretion, into rats with compensated (urinary sodium excretion > 1200 microEq/day) and decompensated CHF (urinary sodium excretion < 200 microEq/day). ETA is predominantly localized to the cortex mainly in the peritubular capillaries, and is upregulated in rats with compensated and decompensated CHF compared with sham controls. In contrast, ETB is preferentially expressed in the outer and inner medulla, mainly in the vasa recta, the thick ascending limb of Henle's loop and the collecting duct. While compensated CHF is associated with upregulation of ETB in the collecting duct and vasa recta, decompensated CHF is accompanied with enhanced ETB abundance in the vasa recta and remarkable downregulation of this receptor subtype in the collecting duct. The findings suggest that upregulation of ETA may lead to a decrease in cortical blood flow while upregulation of ETB in the vasa recta probably contributes to the preservation of medullary blood flow. Furthermore, downregulation of ETB in the collecting duct, only in rats with decompensated CHF, could contribute to sodium retention in that subgroup.

Renal and systemic effects of chronic blockade of ET(A) or ET(B) receptors in normal rats and animals with experimental heart failure.

Endothelin-1 (ET-1) is involved in the pathogenesis of cardiac and renal hemodynamic changes and impaired excretory function in congestive heart failure. It has previously been demonstrated that acute administration of ABT-627 (endothelin-A blocker) abolished systemic and renal vasoconstriction in controls and rats with congestive heart failure induced by a surgically created aortocaval fistula (Abassi et al. Clin Sci (Lond) 2002;103:S245-S248). In contrast, acute endothelin-B blockade by A-192621 exaggerated the ET-1 induced systemic and renal vasoconstriction. The present study examined the renal and systemic effects of chronically administered ABT-627 (24 mg/kg per day) or A-192621 (72 mg/kg per day) for 7 days via osmotic minipumps inserted intraperitoneally on the day of operation of sham controls and rats with congestive heart failure. Tailcuff measurements revealed that ABT- 627 significantly decreased mean arterial pressure from 108 +/- 2 mmHg to 87 +/- 2 mmHg (P < 0.05), whereas A-192621 significantly increased mean arterial pressure from 110 +/- 3 mmHg to 122 +/- 3 mmHg (P < 0.05) in controls. Despite the hypotensive effect of ABT-627, daily sodium excretion dramatically increased, but to a lesser extent in A-192621-treated controls. Furthermore, chronic administration of ABT-627 to controls attenuated the systemic and renal vasoconstriction induced by ET-1 (1 nmol/kg intravenous), whereas A-192621 augmented these effects. Similarly, chronic treatment with ABT-627 totally abolished the systemic and renal vasoconstriction caused by injected ET-1 in rats with congestive heart failure, whereas A192621 potentiated these effects. Chronic treatment of animals with congestive heart failure with ABT-627 did not influence daily sodium excretion, whereas treatment with A192621 significantly improved daily sodium excretion. Interestingly, treatment with either ABT-627 or A192621 significantly decreased cardiac hypertrophy in rats with congestive heart failure. In conclusion, in sham controls endothelin-B receptor mediated vasodilation and natriuresis, probably as a result of tubular action, whereas in congestive heart failure the excretory contribution of endothelin-B receptor was attenuated, resulting in Na+ retention.

Effects of endothelin receptors ET(A) and ET(B) blockade on renal haemodynamics in normal rats and in rats with experimental congestive heart failure.

The present study examined the effects of two highly selective endothelin-1 (ET-1) receptor antagonists, ABT-627 (ET(A) blocker) and A-192621 (ET(B) blocker), on the systemic and renal haemodynamic effects of ET-1 in normal rats and in rats with experimental congestive heart failure (CHF) produced by aortocaval fistula. Intravenous injection of ET-1 (1.0 nmol x kg(-1) of body weight) to anaesthetized normal rats produced sustained decreases in renal blood flow (RBF) (assessed by ultrasonic flowmetry) and glomerular filtration rate (GFR), and significant increases in renal vascular resistance (RVR) and mean arterial pressure (MAP). Pretreatment with ABT-627 (1 mg x h(-1) x kg(-1) of body weight) abolished the pressor response to ET-1 without affecting the depressor phase, and significantly impaired the renal vasoconstriction. The systemic and renal vasoconstrictive effects of ET-1 in normal rats were significantly augmented by pretreatment with 3.0 mg x h(-1) x kg(-1) of A-192621. Baseline RBF and GFR in rats with CHF were reduced significantly compared with control rats, whereas RVR was elevated. The hypertensive effect of ET-1 was attenuated in rats with CHF. In the presence of ET(A) blockade, the pressor response to ET-1 was completely abolished in CHF rats. Furthermore, pretreatment with ABT-627 enhanced the recovery from ET-1- dependent vasoconstriction and remarkably reversed the ET-1-induced hypofiltration. Blockade of ET(B) receptors in rats with CHF further exposed the exaggerated ET-1-induced renal vasoconstriction. Our data demonstrate that experimental CHF is associated with altered responsiveness to ET(A)- and ET(B)-mediated systemic and renal effects of ET-1. Furthermore, in CHF, as in control rats, the ET(B)-mediated vasodilatory response may serve as an important compensatory counterbalance to the adverse ET(A)-mediated effects.