Pressure Injury Development, Mitigation, and Outcomes of Patients Proned for Acute Respiratory Distress Syndrome.

OBJECTIVE: To describe trends and risk factors for pressure injuries (PIs) in adult critical care patients proned to alleviate acute respiratory distress syndrome secondary to COVID-19 and examine the effectiveness of products and strategies used to mitigate PIs. METHODS: The authors conducted a retrospective chart review between April 9 and June 8, 2020. Demographic data were analyzed using descriptive statistics. Differences between groups with and without PIs were analyzed. RESULTS: Among 147 patients, significant PI risk factors included male sex (P = .019), high body mass index (>40 kg/m2; P = .020), low Braden Scale score (<12; P = .018), and low-dose vasopressor therapy (P = .020). Taping endotracheal tubes (ETTs) caused significantly fewer facial PIs than commercial ETT holders (P < .0001). Maximum prone duration/session was a significant risk factor for anterior PIs (P = .016), which dropped 71% with newer pressure redistribution products. d-Dimer greater than 3,200 µg/mL (P = .042) was a significant risk factor for sacrococcygeal PIs while supine. Mortality was 30%; significant risk factors included age older than 60 years (P = .005), Sequential Organ Failure Assessment score greater than 11 (P = .003), and comorbid congestive heart failure (P = .016). CONCLUSIONS: Taping the ETT, limiting the maximum duration of prone positioning to less than 32 hours, and frequent repositioning while supine may reduce the number of modifiable risk factors for PIs. Standardized methods for testing products for PI prevention will inform individualized patient care.

Shoot dieback during prolonged drought in Ceanothus (Rhamnaceae) chaparral of California: a possible case of hydraulic failure.

Progressive diebacks of outer canopy branchlets of Ceanothus crassifolius were repeatedly observed after rainless periods up to 9 mo in duration in the Santa Monica Mountains of southern California. Mean xylem pressures of branchlets near the end of drought were as low as -11.2 MPa (N = 22) with a mean of about 60 dead branchlets per shrub. Inoculation (N = 15) with three species of fungi previously isolated from the same population of C. crassifolius did not promote dieback, suggesting that the observed decline was not fungal induced, as had been proposed. Further, at least 50% of healthy-appearing twigs, without symptoms of dieback, contained isolatible endophytic fungi. We used a centrifugal force method to determine the range of xylem pressure causing cavitation (vulnerability curves) for branchlets (N = 12) and roots (N = 16). We combined vulnerability curves with soil texture data (N = 6) into a water transport model that estimated the critical values (P(Lcrit)) of leaf xylem pressure associated with the loss of water from soil to foliage. Maximum P(Lcrit) was between -10 and -11 MPa and within the range of minimum measured xylem pressures of branchlets during drought and dieback. Branchlet dieback correlated with seasonal declines in xylem pressure in concert with declining safety margins from hydraulic failure. Symptoms of dieback were duplicated in the field by partially severing stem xylem that normally supplied branchlets with water. Taken together, these results indicate that loss of hydraulic conductance to foliage was the probable cause of the observed dieback in C. crassifolius. Partial dieback of peripheral branchlets, and its attendant reduction in evaporative surface area, may be a last-resort mechanism for whole-plant water conservation and drought survival in this species.