Flow Nasal Cannula Oxygen Therapy Research Articles

High flow nasal cannula oxygen therapy prevents hypoxia and hypercapnia even TOE insertion

Introduction The use of transoesophageal ultrasound (TOE) is often cited as a limitation in TAVI under local anaesthesia and sedation. The reason is that moderate or deeper sedation is required when using TOE because of its invasiveness, and if deep sedation is used, its respiratory depression becomes stronger and airway and respiratory management become unstable. High flow nasal cannula oxygen therapy (HFNC) is a device that has recently been attracting attention as one that is expected to have oxygenation and ventilation assistance effects by using a high flow of humidified gas. We inserted TOE and managed by using HFNC in TAVI under local anaesthesia and sedation. After entering the room and securing various monitors and arterial pressure lines, HFNC was started with FiO2 40%, flow 40L. For induction of anaesthesia, fentanyl 0.5-1 mcg / kg and Propofol 20-30 mg were administered. After the disappearance of the eyelash reflex was confirmed, TOE was inserted after local anaesthesia to the pharynx with 8% Lidocaine spray. The state of anaesthesia was maintained at Propofol 2 mg / kg / hr and Remifentanil 0.01-0.03 mcg / kg / min. Methods A retrospective chart review was conducted from April 2017 to March 2018, and arterial blood gas analysis data at induction of anaesthesia (PaO2, PaCO2, BE), intubation event incidence rate and its breakdown were examined. Defects in the description were excluded. Results There were 88 cases in the period. Six cases were intubation cases, but 2 cases were intubated condition from before operation, 3 cases were extracorporeal circulation introduction due to hemodynamic instability, 1 case was due to coronary artery occlusion and There was no intubation and general anaesthesia due to anaesthesia related and patient movement control difficulty. Arterial blood gas analysis data were PaO 2 138.3 mmHg 95%CI[125.9, 150.7], PaCO 2 37.5 mmHg, 95%CI[35.7, 39.3], BE 0.09mEq/l, 95%CI[-0.60, 0.79]. Discussion Hypoxemia or hypercapnia did not occur even under moderate to deep sedation where TOE insertion did not cause movement. HFNC can suppress the occurrence of hypoxemia and hypercapnia even in moderate to deep sedation where TOE insertion is possible.

High Flow Nasal Cannula Oxygen vs. Conventional Oxygen Therapy and Noninvasive Ventilation in Emergency Department Patients: ASystematic Review and Meta-Analysis.

Acute respiratory failure (ARF) is a common cause of presentation to the Emergency Department (ED). High flow nasal cannula (HFNC) has been introduced as an alternative way to administer oxygen. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing HFNC with conventional oxygen therapy (COT) and noninvasive ventilation (NIV) exclusively in the ED setting. Inclusion criteria were: RCTs on adults with ARF admitted to the ED, investigating HFNC vs. COT or other modes of ventilation. Trials that compared HFNC support outside the ED, were published as an abstract, or nonrandomized were excluded. Four RCTs comparing HFNC with COT and one HFNC to NIV met the criteria. Overall, 775 patients were included. The meta-analysis of the studies comparing HFNC and COT showed no differences in intubation requirement, treatment failure, hospitalization, or mortality. Intolerance was significantly higher with HFNC (risk ratio 6.81 95% confidence interval 1.18-39.19; p=0.03). In the only available RCT comparing HFNC with NIV, no difference was found for intubation rate, treatment failure, tolerance, and dyspnea. We did not find any benefit of HFNC compared with COT and NIV in terms of intubation requirement, treatment failure, hospitalization, and mortality; COT was better tolerated.

Comparison of Patient Work of Breathing and Tidal Volumes With High Flow Nasal Cannula Oxygen Therapy and NIV (Non-Invasive Ventilation) After Extubation in the ICU.

Comparison of Patient Work of Breathing and Tidal Volumes With High Flow Nasal Cannula Oxygen Therapy and NIV (Non-Invasive Ventilation) After Extubation in the ICU.

High flow nasal cannula oxygen therapy versus non-invasive ventilation for chronic obstructive pulmonary disease with acute-moderate hypercapnic respiratory failure: an observational cohort study [Corrigendum

High flow nasal cannula oxygen therapy versus non-invasive ventilation for chronic obstructive pulmonary disease with acute-moderate hypercapnic respiratory failure: an observational cohort study [Corrigendum] Sun J, Li Y, Ling B, Zhu Q, Hu Y, Tan D, Geng P, Xu J. Int J Chron Obstruct Pulmon Dis. 2019;14:1229–1237.The author has advised that an error occurred in the numbering of the second and third affiliations in the affiliations list. The correct affiliations list for this paper should appear as follows:Jiayan Sun,1 Yujie Li,1 Bingyu Ling,1 Qingcheng Zhu,1 Yingying Hu,2 Dingyu Tan,1 Ping Geng,1 Jun Xu31Department of Emergency, Clinical Medical College, Yangzhou University, Northern Jiangsu People’s Hospital, Yangzhou, People’s Republic of China; 2Department of Emergency, The First Affiliated Hospital and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, People’s Republic of China; 3Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, People’s Republic of ChinaRead the original article

<p>High flow nasal cannula oxygen therapy versus non-invasive ventilation for chronic obstructive pulmonary disease with acute-moderate hypercapnic respiratory failure: an observational cohort study</p>

BackgroundHigh-flow nasal cannula (HFNC) oxygen therapy in acute hypoxic respiratory failure is becoming increasingly popular. However, evidence to support the use of HFNC in acute respiratory failure (ARF) with hypercapnia is limited.MethodsChronic obstructive pulmonary disease (COPD) patients with moderate hypercapnic ARF (arterial blood gas pH 7.25–7.35, PaCO2>50 mmHg) who received HFNC or non-invasive ventilation (NIV) in the intensive care uint from April 2016 to March 2018 were analyzed retrospectively. The endpoint was treatment failure, defined as either invasive ventilation, or a switch to the other study treatment (NIV for patients in the NFNC group, and vice-versa), and 28-day mortality.ResultsEighty-two COPD patients (39 in the HFNC group and 43 in the NIV group) were enrolled in this study. The mean age was 71.8±8.2 and 54 patients (65.9%) were male. The treatment failed in 11 out of 39 patients with HFNC (28.2%) and in 17 of 43 patients with NIV (39.5%) (P=0.268). No significant differences were found for 28-day mortality (15.4% in the HFNC group and 14% in the NIV group, P=0.824). During the first 24 hrs of treatment, the number of nursing airway care interventions in the HFNC group was significantly less than in the NIV group, while the duration of device application was significantly longer in the HFNC group (all P<0.05). Skin breakdown was significantly more common in the NIV group (20.9% vs 5.1%, P<0.05).ConclusionAmong COPD patients with moderate hypercarbic ARF, the use of HFNC compared with NIV did not result in increased rates of treatment failure, while there were fewer nursing interventions and skin breakdown episodes reported in the HFNC group.

The importance of high flow nasal cannula (HFNC) oxygen therapy

The importance of high flow nasal cannula (HFNC) oxygen therapy

A pilot study of heated and humidified low flow oxygen therapy: An assessment in infants with mild and moderate bronchiolitis (HHOT AIR study).

Heated and humidified high flow nasal cannula oxygen therapy has been used in children with severe bronchiolitis. No data exists in children with mild to moderate bronchiolitis requiring lower flows of heated and humidified oxygen therapy. We conducted a prospective, randomized pilot study of standard dry oxygen (control) versus heated and humidified low flow nasal cannula (HHLFNC), <4 liters per minute (LPM) oxygen, (treatment) in healthy children ≤24 months old with bronchiolitis. Clinical assessments were made using Respiratory Distress Assessment Instrument (RDAI), respiratory rate (RR), and oxygen saturation. Thirty-two children were enrolled (16 participants in each group). There was no significant difference in mean RDAI over time between groups. There was a significant difference in mean RDAI over time within control group, at hour 12, and treatment group, at hour 1, compared to baseline. RDAI in the treatment group was overall lower over time compared to control group. There was no significant difference in mean RR over time between or within groups, between mean length of stay and duration of oxygen requirement. Subgroup analyses showed lower RDAI in subjects that had RSV infection, male gender, and non-black race. The use of HHLFNC oxygen therapy may provide more comfort and may result in more rapid improvements in RDAI compared to standard dry oxygen therapy over time. HHFLNC is safe and well tolerated compared to standard dry oxygen. Larger studies are needed to assess the clinical efficacy of HHLFNC oxygen therapy.

Nursing practice in patients with extracorporeal membrane oxygenation therapy waiting for lung transplantation

Objective To summarize the nursing experience for extracorporeal membrane oxygenation therapy (ECMO) waiting for lung transplantation. Methods Totally 4 patients waiting for lung transplantation who received ECMO in Shanghai Lung Hospital from May 2017 to June 2018. Nursing management strategies included: building a multidisciplinary medical and nursing team, using awake ECMO strategies in early stages, employing high flow nasal cannulae oxygen therapy to improve oxygenation, monitoring coagulation and anticoagulation, and careful in-hospital transfer process management. Results After careful therapy and nursing care, 3 patients were safely transferred to the operation room for lung transplantation, and 1 died. Conclusions Careful nursing management during ECMO can improve the survival rate of critical patients and guarantee successful lung transplantation and better prognosis. Key words: Lung transplantation; Extracorporeal membrane oxygenation; Critical patients; Nursing experience

Expert consensus of high⁃flow nasal cannula oxygen therapy on clinical application regularity

经鼻高流量湿化氧疗（HFNC）作为一种新的呼吸支持技术近些年来在临床得到广泛应用，该治疗设备主要包括空氧混合装置、湿化治疗仪、高流量鼻塞以及连接呼吸管路，主要关注于给患者提供相对恒定的吸氧浓度（21%~100%）、温度（31~37 ℃）和湿度的高流量（8~80 L/min）气体，并通过鼻塞进行氧疗，具有很好的舒适性。HFNC能够通过吸入高流量气体产生一定水平的呼气末正压、冲刷上呼吸道生理死腔、恒温恒湿的气体维持黏液纤毛清除系统功能以及降低患者上气道阻力和呼吸功等作用改善患者的换气和部分通气功能，对单纯低氧性呼吸衰竭（Ⅰ型呼吸衰竭）患者具有积极的治疗作用，对部分轻度低氧合并高碳酸血症（Ⅱ型呼吸衰竭）患者可能也具有一定的治疗作用，但尚需要大样本的临床研究证实。需要指出的是，HFNC的局限性也应正确认识。明确其适应证和禁忌证、规范临床应用势在必行，中华医学会呼吸病学分会呼吸危重症医学学组和中国医师协会呼吸医师分会危重症医学工作委员会牵头撰写成人经鼻高流量湿化氧疗临床规范应用专家共识，对规范国内HFNC的临床应用具有积极的意义。.

Determination of carboxyhemoglobin half-life in patients with carbon monoxide toxicity treated with high flow nasal cannula oxygen therapy

Background: Acute carbon monoxide poisoning is a common environmental emergency worldwide. Treatment options are limited to normobaric oxygen therapy with a nonrebreather face mask or endotracheal tube and hyperbaric oxygen. The aim of this study is to determine the half-life of carboxyhemoglobin (COHb) in adult patients admitted to the emergency department with acute carbon monoxide poisoning receiving high flow nasal cannula (HFNC) oxygen. Device tolerability and patient comfort with the high flow nasal cannula were also evaluated.Methods: This study was conducted between January 2017 and February 2018 in two academic emergency departments. Venous blood samples were obtained at 10 minute intervals to determine the rate of elimination of COHb. Patient comfort was evaluated by a verbal numeric rating scale. The primary outcome was the determination of the half-life of COHb. The secondary outcome was device tolerability and patient comfort with the high flow nasal cannula oxygen delivery system.Results: A total of 33 patients were enrolled in the study. The mean baseline COHb level of the patients was 22.5% (SD 8%). The mean half-life of carboxyhemoglobin was determined as 36.8 minutes (SD 9.26 min) with high flow nasal cannula oxygen. COHb levels were halved during the first 40 minutes in 22 (67%) of the study patients. Twenty of the patients receiving HFNC oxygen did not report intolerance or discomfort. Among the 11 patients who requested a change in the flow rate, the median verbal numeric rating score was 7. After decreasing the flow rate, the median verbal numeric rating score was 9.Conclusion: High flow nasal cannula oxygen is an easy, safe, comfortable and effective method to reduce COHb. HFNC may be a promising alternative method if it is validated as effective in future studies with clinical outcomes.

经鼻高流量氧疗在呼吸危重症患者中的应用

经鼻高流量氧疗在呼吸危重症患者中的应用

Long-term high flow nasal cannula oxygen therapy

Long-term high flow nasal cannula oxygen therapy

Satisfactory use of high flow nasal cannula in a patient with acute pulmonary embolism

High Flow Nasal Cannula (HFNC) oxygen therapy is a recent technique that delivers a high flow of heated and humidified gas to the patient.1 Compared to noninvasive ventilation (NIV), HFNC has been proved to be an effective alternative treatment for acute respiratory failure. HFNC also has a significant number of physiological advantages compared with other commonly used oxygen-based therapies, including PEEP, reduced anatomical dead space, constant FiO2 and it is better tolerated than NIV.2 After a thorough bibliographical research, only one article was found assessing the benefits of using HFNC in patients with acute pulmonary embolism.3 We present the case of an 86-year-old patient with acute pulmonary embolism and desaturation refractory to noninvasive ventilation that was successfully treated with high flow therapy.

Management of severe acute exacerbations of COPD: an updated narrative review

Background: Patients with chronic obstructive pulmonary disease (COPD) may experience an acute worsening of respiratory symptoms that results in additional therapy; this event is defined as a COPD exacerbation (AECOPD). Hospitalization for AECOPD is accompanied by a rapid decline in health status with a high risk of mortality or other negative outcomes such as need for endotracheal intubation or intensive care unit (ICU) admission. Treatments for AECOPD aim to minimize the negative impact of the current exacerbation and to prevent subsequent events, such as relapse or readmission to hospital. Main body: In this narrative review, we update the scientific evidence about the in-hospital pharmacological and non-pharmacological treatments used in the management of a severe AECOPD. We review inhaled bronchodilators, steroids, and antibiotics for the pharmacological approach, and oxygen, high flow nasal cannulae (HFNC) oxygen therapy, non-invasive mechanical ventilation (NIMV) and pulmonary rehabilitation (PR) as non-pharmacological treatments. We also review some studies of non-conventional drugs that have been proposed for severe AECOPD. Conclusion: Several treatments exist for severe AECOPD patients requiring hospitalization. Some treatments such as steroids and NIMV (in patients admitted with a hypercapnic acute respiratory failure and respiratory acidosis) are supported by strong evidence of their efficacy. HFNC oxygen therapy needs further prospective studies. Although antibiotics are preferred in ICU patients, there is a lack of evidence regarding the preferred drugs and optimal duration of treatment for non-ICU patients. Early rehabilitation, if associated with standard treatment of patients, is recommended due to its feasibility and safety. There are currently few promising new drugs or new applications of existing drugs.

HIGH FLOW NASAL CANNULA OXYGEN USE IN OCTOGENARIAN AND NONAGENARIAN PATIENTS: A RETROSPECTIVE ANALYSIS AMONG MICU PATIENTS

SESSION TITLE: Critical Respiratory Care SESSION TYPE: Original Investigations PRESENTED ON: 10/08/2018 07:30 AM - 08:30 AM PURPOSE: High flow nasal cannula (HFNC) oxygen(O2) therapy delivers heated and humidified gas with flow rates up to 60 L/min. It also provides a small PEEP effect, reduces anatomical dead space, and provides a constant fraction of inspired oxygen(FiO2). It has been extensively studied in pediatric population and has lately gained popularity in adult patient population although evidence for use in critically ill adults still remains poor. Additionally, to our knowledge, evidence of its use in patients 80 years of age and above has not been assessed. We attempt to study the indications and effects of HFNC use in patients 80 years of age and above in the medical intensive care unit (MICU) of a tertiary care hospital. METHODS: 40 patients 80 years of age and above who required HFNC O2 in the MICU for more than 12 hours between 01/01/2016 and 08/01/2017 were identified. Retrospective chart review was performed and data related to HFNC O2 use was obtained. Data included age, diagnosis, indication for HFNC, duration of HFNC use, initial FiO2 and flow rate, modality of oxygenation used before and after HFNC, disposition and code status. The data was charted on a spreadsheet and analyzed by calculating percentage associated with various variables. RESULTS: Mean age of the patients was 89.025 years. Mean duration of HFNC O2 use was 5 days. Mean initial FiO2 was 45.625%. Mean initial flow rate was 42.75 L/min. Most common indication for HFNC use was hypoxemia post extubation. Most common diagnosis was sepsis due to pneumonia. 52.5%(21/40) patients were transitioned to HFNC O2 post extubation. 47.5%(19/40) were transitioned from nasal cannula(NC) or bilevel positive airway pressure ventilation (BPAP). 15%(6/40) had to be intubated and mechanically ventilated after HFNC O2 use whereas 85%(34/40) were downscaled to regular NC O2. Of the 6 intubations, 3 were re-intubations. 12.5%(5/40) patients expired whereas 87.5%(35/40) patients were discharged from the hospital. Code status for 4 patients was changed to comfort care with do not intubate(DNI) after extubation to HFNC, 2/4 were discharged and the other 2 expired. CONCLUSIONS: This study revealed a positive outcome with respect to use of HFNC O2 in patients 80 years of age and above. Majority (87.5%) of the patients were discharged from the hospital. Intubation(15%) and re-intubation rates were low after use of HFNC O2. Patients who opted for comfort care (DNR/DNI) but could not maintain optimum oxyhemoglobin saturation with NC O2 and found BPAP uncomfortable, benefitted from HFNC with respect to comfort and compliance per chart review. CLINICAL IMPLICATIONS: Elderly patients might benefit from HFNC O2 especially after liberation from mechanical ventilation. Elderly patients with hypoxemic respiratory failure who opt for comfort care but cannot maintain optimum oxyhemoglobin saturation with NC O2 and find BPAP uncomfortable could also benefit from HFNC O2 use. DISCLOSURES: No relevant relationships by Prarthna Chandar, source=Web Response No relevant relationships by Yizhak Kupfer, source=Web Response No relevant relationships by Anand Rai, source=Web Response No relevant relationships by Arjun Saradna, source=Web Response No relevant relationships by Ben Shamian, source=Web Response No relevant relationships by Shyam Shankar, source=Web Response

Comparison of high flow nasal cannula oxygen and conventional oxygen therapy on ventilatory support duration during acute-on-chronic respiratory failure: study protocol of a multicentre, randomised, controlled trial. The ‘HIGH-FLOW ACRF’ study

IntroductionThis study protocol describes a trial designed to investigate whether high-flow heated and humidified nasal oxygen (HFHO) therapy in patients with hypercapnic acute respiratory failure (ARF) reduces the need of...

High flow nasal cannula oxygen therapy versus non-invasive ventilation for chronic obstructive pulmonary diseases with acute-moderate hypercapnic respiratory failure: an observational cohort study

Objective To compare the efficacy of high flow nasal cannula oxygen therapy (HFNC) and non-invasive ventilation (NIV) in the treatment of chronic obstructive pulmonary disease (COPD) with acute-moderate typeⅡ respiratory failure, and to explore the feasibility of HFNC in the treatment of COPD with respiratory failure. Methods Patients diagnosed with COPD with acute moderate typeⅡ respiratory failure (Arterial blood gas pH 7.25-7.35, PaCO2> 50 mmHg) admitted to the ICUs from April 2017 to December 2017 were retrospectively analyzed. All patients who were treated with HFNC within the first 4 hours after the admission to the ICUs, and continued for more than 2 hours and for at least 4 hours within the first 24 hours were included in the HFNC group. Those treated with NIV in the same conditions were included in the NIV group. The end point was the failure rates of treatment (changing to respiratory support method in another group or invasive ventilation) and 28-day mortality. Results Eighty-two patients (39 in the HFNC group and 43 in the NIV group) were enrolled. The HFNC group had a treatment failure rate of 28.2%, which was lower than that of the NIV group (39.5%). However, Kaplan-Meier curve analysis showed no significant difference between the two groups (Log Rank test 1.228, P=0.268). The 28-day mortality rate in HFNC group was 15.4%, which was no different from 14% in NIV group (Log Rank test 0.049, P=0.824). The number of airway care interventions within the first 24 hours was significantly lower in the HFNC group than in the NIV group [5 (3~8) vs. 11 (7~15)], whereas the duration of respiratory support within the first 24 hours was significantly longer in the HFNC group than in the NIV group [16 (9~22) hours vs. 8 (4~11) hours] (all P<0.05). The incidence of nasal facial lesions in the NIV group was 20.9%, significantly higher than that of HFNC group (5.1%, P <0.05). Conclusion For COPD with acute moderate typeⅡ respiratory failure, HFNC has similar therapeutic effects as NIV. HFNC has better therapeutic tolerance and is a new potential respiratory support method for clinical treatment of COPD with respiratory failure. Key words: Chronic obstructive pulmonary diseases; Respiratory failure; High-flow nasal cannula oxygen therapy; Non-invasive ventilation; Cohort study

High flow nasal cannulae oxygen therapy in acute-moderate hypercapnic respiratory failure.

Severe acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is a significant event that results in substantial mortality. We evaluated the effectiveness of the high flow nasal cannulae (HFNC) therapy in severe AECOPD with moderate hypercapnic acute respiratory failure (ARF) compared to non-invasive ventilation (NIV). The prospective observational trial was performed to compare the effectiveness between the HFNC and NIV in severe AECOPD with moderate hypercapnic ARF. The end point was the intubation rate and 30-day mortality. Ninety-two AECOPD patients enrolled during study periods. The median age was 73 (66.5-79)years, and 57 patients (64.8%) were male. Forty-four patients were assigned to HFNC, and 44 patients were assigned to NIV. The intubation rate at day 30 was 25.0% in the HFNC group and 27.3% in the NIV group (P=.857), and the 30-day mortality was 15.9% in the HFNC group and 18.2% in the NIV group (P=.845). The pH (7.38±0.59 vs 7.36±0.10, P=.295), PaO2 (82.2±24.9 vs 81.6±21.7mm Hg, P=.899) and PaCO2 (46.8±15.2 vs 51.7±17.2mm Hg, P=.160) after 6hours and the pH (7.39±0.07 vs 7.39±0.08, P=.743), PaO2 (84.3±18.5 vs 84.7±23.2mm Hg, P=.934) and PaCO2 (47.0±16.0 vs 49.6±13.7mm Hg, P=.422) after 24 hours were not significantly different. There was no difference of the 30-day mortality and intubation rate between HFNC and NIV groups.

High flow nasal oxygen therapy utilization: 7-year experience at a community teaching hospital

ABSTRACTObjective: To examine the use of high flow nasal cannula oxygen therapy (HFNC) between 2008 and 2014 in patients 18 years or older at a community teaching hospital.Methods: Yearly utilization rates of HFNC, noninvasive ventilation (NIV) and invasive mechanical ventilation (IMV) were calculated among admissions with a set of cardiopulmonary diagnoses (heart failure, COPD, asthma or pneumonia).Results: Among the 41,711 admissions with at least one of the above cardiopulmonary condition, HFNC was utilized in 1,128 or 27.0/1000; NIV was used in an average of 169/1000 and IMV in 231/1000. HFNC was accompanied by IMV or NIV 71.3% of the time. From 2008 to 2014 HFNC utilization increased an average of 17.5% annually; NIV increased by 10.2% annually while IMV’s utilization increased by 1.6% annually. The highest rate of change in HFNC use was among admissions with pneumonia and those with COPD.Conclusion: HFNC utilization increased steadily over a 7-year period at our hospital. Frequently, HFNC therapy was used in combination with other ventilatory modes to support patients’ respiration. Similar with other technologies in healthcare, the uptake of HFNC has preceded the evidence from robust clinical trials.

Nursing care of patients with lung transplantation patients receiving high flow nasal cannulae oxygen therapy during perioperative period

Objective To summarize the experiences of postoperative care of 7 patients with lung transplantation patients receiving high flow nasal cannulae oxygen therapy. Methods The key points to ensure the success of operation were oxygen therapy waiting for lung transplantation, sequential treatment after tracheal intubation, assisted by fiberoptic bronchoscopy, nasal high flow oxygen therapy failed to switch to non-invasive treatment or re intubation. Results All 7 patients got through the intensive care period successful. Conclusions High flow nasal cannulae can improve the comfort and compliance of lung transplant patients, and easy to operate. Key words: Nursing care; Lung transplantation; High flow nasal cannulae oxygen therapy