Ten-year territory-wide trends in the utilisation and clinical outcomes of extracorporeal membrane oxygenation in Hong Kong.

INTRODUCTION: The utilisation of extracorporeal membrane oxygenation (ECMO) has been rapidly increasing in Hong Kong. This study examined 10-year trends in the utilisation and clinical outcomes of ECMO in Hong Kong. METHODS: We retrospectively reviewed the records of all adult patients receiving ECMO who were admitted to the intensive care units (ICUs) of public hospitals in Hong Kong between 2010 and 2019. Temporal trends across years were assessed using the Mann-Kendall test. Observed hospital mortality was compared with the Acute Physiology and Chronic Health Evaluation (APACHE) IV-predicted mortality. RESULTS: The annual number of patients receiving ECMO increased from 18 to 171 over 10 years. In total, 911 patients received ECMO during the study period: 297 (32.6%) received veno-arterial ECMO, 450 (49.4%) received veno-venous ECMO, and 164 (18.0%) received extracorporeal cardiopulmonary resuscitation. The annual number of patients aged ≥65 years increased from 0 to 47 (27.5%) [P for trend=0.001]. The median (interquartile range) Charlson Comorbidity Index increased from 1 (0-1) to 2 (1-3) [P for trend<0.001] while the median (interquartile range) APACHE IV score increased from 90 (57-112) to 105 (77-137) [P for trend=0.003]. The overall standardised mortality ratio comparing hospital mortality with APACHE IV-predicted mortality was 1.11 (95% confidence interval=1.01-1.22). Hospital and ICU length of stay both significantly decreased (P for trend=0.011 and <0.001, respectively). CONCLUSION: As ECMO utilisation increased in Hong Kong, patients put on ECMO were older, more critically ill, and had more co-morbidities. It is important to combine service expansion with adequate resource allocation and training to maintain quality of care.

A prospective study on serum citrate levels and clinical correlations in patients receiving regional citrate anticoagulation.

Background: Current ways to diagnose citrate accumulation (CA) in patients receiving regional citrate anticoagulation (RCA) continuous renal replacement therapy (CRRT) are confounded by various clinical factors. Serum citrate measurement emerges as a more direct way to diagnose CA, but its clinical utility and optimal cut-off values remain undefined. This study examined serum citrate kinetics and its diagnostic performance for CA in patients receiving RCA CRRT. Methods: A multicentre prospective study was carried out in two tertiary referral centre intensive care units in Hong Kong with serum citrate levels measured at baseline and 2, 6, 12, 24, 36, 48 and 72 h after initiation of RCA CRRT and their relationships with the development of CA. Results: Among the 133 patients analysed, 18 patients (13.5%) developed CA. The serum citrate levels at baseline and 2, 6 and 12 h after initiation of RCA CRRT in patients who had CA were significantly higher than the non-CA group (P < .001 for all). The CA group also had higher serum citrate levels than the non-CA group {median 0.93 mmol/L [interquartile range (IQR) 0.81-1.16) versus 0.37 mmol/L (IQR 0.26-0.57), P < .001}. Using a cut-off of 0.85 mmol/L, the serum citrate level had a sensitivity of 0.77 and a specificity 0.96 for the diagnosis of CA [area under the receiver operating characteristics curve (AUROC) 0.90, P < .001]. The 2-h and 6-h serum citrate levels had good discriminatory abilities for predicting subsequent development of CA (AUROC 0.86 and 0.83 for 2-h and 6-h citrate levels using cut-off values of 0.34 and 0.63 mmol/L, respectively; P < .001). Conclusion: Serum citrate levels were significantly higher in patients with CA compared with patients without CA. Serum citrate levels showed good performance in diagnosing and predicting the development of CA.

Interaction of natriuretic peptides and cGMP production via the same receptor in mouse astrocytes.

Atrial and brain natriuretic peptides have been found previously to bind to specific receptors on cultured mouse astrocytes and to stimulate cyclic guanosine 5-monophosphate (cGMP) production with similar dose dependency although brain natriuretic peptide (BNP) shows a greater maximal stimulatory effect. The present study provides evidence that both peptides work through the same pathway. No additive or synergistic effect was observed when astrocytes were exposed to both peptides. However, human ANF(99-126) at high concentrations partially inhibited porcine BNP induced cGMP production to the level seen with ANF alone. ANF could be viewed as a partial agonist of pBNP competing for the same effector sites. Differences in structure between human ANF(99-126) and porcine BNP may account for the difference in cGMP response. The interaction between the two peptides and the cGMP response does not reflect receptor binding affinities and is likely to be a post-binding event.

Joint processing of hartmann sensor and conventional image measurements to estimate large aberrations: theory and experimental results.

We report experimental results for what we believe to be a new technique for estimating aberrations that extends the strength of an aberration that may be sensed with Hartmann sensor technology by means of an algorithm that processes both a Hartmann sensor image and a conventional image formed with the same aberration. We find that the theory and the experiment match well within the experimental error and that strong defocus aberrations can be accurately sensed with this technique.