ABSTRACT
STUDY OBJECTIVES: To assess the prevalence of preoperative acidosis and lactatemia in elderly patients having hip fracture surgery and their association with post-operative mortality. DESIGN: Retrospective cohort study. SETTING: Single tertiary medical center. PATIENTS: Patients ≥65 years having first traumatic hip fracture surgery between 2018 and 2021. MEASUREMENTS: 90-day postoperative mortality. MAIN RESULTS: In total, 1267 patients were included in the primary analysis (mean (SD) age 83(8) years; 802 (69%) females; median [Interquartile Range (IQR)] American Society of Anesthesiologists (ASA) physical score 3 [2,3]). Of these, 1227 were available for the multivariable analyses. Median [IQR] time from hospitalization to surgery was 28 [20, 42] hours. All-cause 90-day mortality rate was 9% (N = 114). The incidence of preoperative acidosis (pH < 7.35) and lactatemia (>1.2 mmol/L) was significantly higher among non-survivors. Mortality was highest in patients with both acidosis and lactatemia (19.1% compared to 4.4% among patients with neither). In a multivariable model, pH <7.35 and lactate >1.2 mmol/L remained independent predictors of 90-day mortality, with adjusted odds ratio (aOR) (95%CI) of 1.99 (1.31 to 3.04) and 2.32 (1.44 to 3.74), respectively, p = 0.001 for both. Time from hospitalization to surgery was not associated with mortality after adjustment for metabolic indices, aOR 1.00 (0.99, 1.00). CONCLUSIONS: Preoperative acidosis and lactatemia are common among patients ≥65 years having hip fracture surgery and are associated with 90-day all-cause mortality. Time from hospital admission to surgery is not an independent risk factor, once adjusted for metabolic indices. Future studies should evaluate whether the increased risk associated with preoperative metabolic disturbances is modifiable.
Subject(s)
Hip Fractures , Female , Humans , Aged , Aged, 80 and over , Male , Retrospective Studies , Prevalence , Hip Fractures/surgery , Risk Factors , HospitalizationABSTRACT
An electrically controlled holographic switch is proposed as a building block for a free-space optical interconnection network. The switch is based on the voltage-controlled photorefractive effect in KLTN crystals at the paraelectric phase. It is built of electrically controlled Bragg gratings stored in the volume of the crystal. A compact switch that connects four high-speed fiber-optic communication channels with high efficiency is demonstrated experimentally. The switch performance is investigated and optimized. This switch is extremely attractive for cascaded switching arrays such as those found in multistage interconnect networks.
ABSTRACT
We report the first observation of spatial one-dimensional photorefractive screening solitons in centrosymmetric media and compare the experimental results with recent theoretical predictions. We find good qualitative agreement with theory.
ABSTRACT
High holographic storage capacity of paraelectric K(1-x)Lix Ta(1-y) Nby O(3):Cu , V using the voltage-controlled photorefractive effect is experimentally demonstrated. Measurements of the M/# for various writing angles and reading fields are presented. In particular, it is shown that 128 angularly multiplexed holograms, written by two plane-wave beams separated by an angle of 8 degrees , yield an M/# of 20.
ABSTRACT
Electric-field multiplexing (EFM) results from the tuning of the effective wavelength of the light beam inside a photorefractive crystal. This tuning results from the application of an external electric field to the crystal during holographic recording. We demonstrate the high Bragg selectivity of this multiplexing technique in paraelectric crystals and compare it with the selectivity obtained in the ferroelectric phase. The effects of the two major physical parameters of working in the paraelectric phase, the temperature and the external electric field applied during the writing stage, are investigated. Experimental results of the EFM of three image-bearing holograms recorded in reflection geometry are presented along with a qualitative analysis of the Bragg selectivity in paraelectric crystals.
ABSTRACT
We describe a new approach for constructing large-scale artificial neural networks. The novelty of our approach is based on the concept of electroholography (EH), which permits interconnecting of electronic neurons by minute-volume holograms, using the voltage-controlled photorefractive effect in paraelectric crystals. Crystals of potassium lithium tantalate niobate (KLTN) in the paraelectric phase are shown to be suitable for implementing this concept. A small network composed of two KLTN crystals on which holographic connections are recorded is presented to demonstrate the EH approach.
