RESUMO
As the use of extracorporeal membrane oxygenation (ECMO) expands, so has the need for interfacility transfer to ECMO centers. However, the impact of these transfers has not been fully studied. This study evaluates complications and inhospital mortality in adult patients treated with venovenous (V-V) ECMO based on institutional location of cannulation and mode of transport. DESIGN: Retrospective cohort study. SETTING: Large midwestern ECMO center. PATIENTS: Adult patients receiving VV-ECMO. INTERVENTIONS: Need for transfer to ECMO center following VV-ECMO cannulation. MEASUREMENTS AND MAIN RESULTS: The study included 102 adult patients, 57% of which were cannulated at an outside institution prior to transfer. Of these, 60% were transported by ground, and the remainder were transported by air. Risk-adjusted logistic regression did not reveal any significant increase in odds for any complication or inhospital mortality between the groups based on location of cannulation or mode of transport. CONCLUSIONS: This study supports the practice of interfacility ECMO transfer with no difference in outcomes or inhospital mortality based on institutional location of cannulation or mode of transport.
RESUMO
A statewide working group in Minnesota created a ventilator allocation scoring system in anticipation of functioning under a Crisis Standards of Care declaration. The scoring system was intended for patients with and without coronavirus disease 2019. There was disagreement about whether the scoring system might exacerbate health disparities and about whether the score should include age. We measured the relationship of ventilator scores to in-hospital and 3-month mortality. We analyzed our findings in the context of ethical and legal guidance for the triage of scarce resources. DESIGN: Retrospective cohort study. SETTING: Multihospital within a single healthcare system. PATIENTS: Five-hundred four patients emergently intubated and admitted to the ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The Ventilator Allocation Score was positively associated with higher mortality (p < 0.0001). The 3-month mortality rate for patients with a score of 6 or higher was 96% (42/44 patients). Age was positively associated with mortality. The 3-month mortality rate for patients 80 and older with scores of 4 or greater was 93% (40/43 patients). Of patients assigned a score of 5, those with end stage renal disease had lower mortality than patients without end stage renal disease although the difference did not achieve statistical significance (n = 27; 25% vs 58%; p = 0.2). CONCLUSIONS: The Ventilator Allocation Score can accurately identify patients with high rates of short-term mortality. However, these high mortality patients only represent 27% of all the patients who died, limiting the utility of the score for allocation of scarce resources. The score may unfairly prioritize older patients and inadvertently exacerbate racial health disparities through the inclusion of specific comorbidities such as end stage renal disease. Triage frameworks that include age should be considered. Purposeful efforts must be taken to ensure that triage protocols do not perpetuate or exacerbate prevailing inequities. Further work on the allocation of scarce resources in critical care settings would benefit from consensus on the primary ethical objective.
RESUMO
Kinesin-1, -2, -5, and -7 generate processive hand-over-hand 8-nm steps to transport intracellular cargoes toward the microtubule plus end. This processive motility requires gating mechanisms to coordinate the mechanochemical cycles of the two motor heads to sustain the processive run. A key structural element believed to regulate the degree of processivity is the neck-linker, a short peptide of 12-18 residues, which connects the motor domain to its coiled-coil stalk. Although a shorter neck-linker has been correlated with longer run lengths, the structural data to support this hypothesis have been lacking. To test this hypothesis, seven kinesin structures were determined by x-ray crystallography. Each included the neck-linker motif, followed by helix α7 that constitutes the start of the coiled-coil stalk. In the majority of the structures, the neck-linker length differed from predictions because helix α7, which initiates the coiled-coil, started earlier in the sequence than predicted. A further examination of structures in the Protein Data Bank reveals that there is a great disparity between the predicted and observed starting residues. This suggests that an accurate prediction of the start of a coiled-coil is currently difficult to achieve. These results are significant because they now exclude simple comparisons between members of the kinesin superfamily and add a further layer of complexity when interpreting the results of mutagenesis or protein fusion. They also re-emphasize the need to consider factors beyond the kinesin neck-linker motif when attempting to understand how inter-head communication is tuned to achieve the degree of processivity required for cellular function.
