Cuff Inflation Research Articles

CAN RECORDING KOROTKOFF SOUNDS DURING BRACHIAL CUFF INFLATION PROVIDE MORE ACCURATE NON-INVASIVE ESTIMATES OF INTRA-ARTERIAL BLOOD PRESSURE?

Objective: We have previously demonstrated that recording onset and termination of Korotkoff sounds as markers of systolic (SBP) and diastolic (DBP) during brachial cuff deflation results in underestimation of true SBP. In this study we explore whether recording Korotkoff sounds during cuff inflation provides more accurate non-invasive estimates of intra-arterial blood pressure (IABP). Design and method: Experiments were carried out on 15 participants, (14 males, 64.3 ± 10.4 years; one female, 86 yo), undergoing coronary angiography. A conventional (oscillometric) BP cuff, with a microphone for Korotkoff sounds, was placed on the upper arm. The cuff was inflated at rate of approximately 2.5mm Hg/sec and deflated at the same rate. Inflation and deflation cycles were randomised and separated by 2 - 3 minutes. IABP was measured below the cuff with a fluid-filled catheter inserted via the radial artery and an external transducer. Korotkoff sounds were processed electronically, and custom algorithms identified the cuff pressure (CP) at which the first and last Korotkoff sounds were heard. Results: Systolic (SBP), and diastolic (DBP) pressure were 147.7.6 ± 12.7 and 70.7 ± 9.7mmHg. The CP at which the brachial artery closes during rapid (∼20mmHg/sec) cuff inflation (132.0 ± 17.1) was similar to that of slow (2.5mmHg/sec) inflation (132.0 ± 16.3 mmHg). However, peak Korotkoff sound energy was significantly reduced (P = 0.003) from 0.19 ± 0.1 to 0.15 ± 0.09 RMS volts and the Korotkoff sounds were often observed to disappear prematurely before brachial artery closure. Difference between intra-arterial SBP and CP at the last recorded Korotkoff sound (27.5 ± 9.3 mmHg) during cuff inflation was significantly higher (P = 0.0025) than during slow cuff deflation (18.9 ± 8.3 mmHg). In contrast, DBP recorded at first onset of the Korotkoff sounds (70.5 ± 11.1 mmHg) was consistently similar to intra-arterial DBP (70.7 ± 9.7 mmHg). Conclusions: SBP estimates derived from the last Korotkoff sound recorded as the cuff inflates generates greater errors than when Korotkoff sounds are first recorded as the cuff deflates. In contrast, the estimate of DBP derived from the first onset of the Korotkoff sound as the cuff inflates, appears to reflect accurately the true intra-arterial DBP.

Effects of remote ischaemic preconditioning on myocardial injury after major abdominal surgery in patients at high risk for cardiovascular adverse events in China (RIPC-MAS): protocol for a randomised, sham-controlled, observer-blinded trial

IntroductionMyocardial injury after non-cardiac surgery (MINS) caused by an ischaemic mechanism is common and is associated with adverse short-term and long-term prognoses. However, MINS is a recent concept, and few...

COMPARISON OF BLOOD PRESSURE MEASUREMENT WITH A CUFFLESS TONOMETRIC WRIST-WORN DEVICE AND CONVENTIONAL BRACHIAL CUFF SPHYGMOMANOMETRY FOR AMBULATORY BLOOD PRESSURE MONITORING

Objective: Ambulatory blood pressure monitoring (ABPM) is used for confirmation of diagnosis of hypertension. However, conventional cuff-based blood pressure (BP) measurement involves the obtrusive procedure of cuff inflation, making multiple measurements over extended periods uncomfortable. This study aims to compare BP measurement using the unobtrusive procedure of radial applanation tonometry with that of the conventional brachial cuff sphygmomanometer for ABPM. Design and method: ABPM (24 hour) was conducted in 16 participants (53±14 years, 4 female) using validated brachial cuff devices (Microlife WatchBPO3, n = 6; BPLab, n = 10) with BP measurements every 15 minutes during daytime and every 30 minutes during nighttime. BP measurements were obtained with a wrist-worn tonometric device (BPro, Healthstats) every 15 minutes, using an initial calibration obtained with the ABPM device. Results: Averaged over 24 hours, tonometric BP estimates correlated with brachial cuff systolic BP (SBP, r = 0.89, p<0.001) but not with diastolic BP (DBP, r = 0.48, p = 0.059) with mean differences (bias) of -4±14 mmHg (SBP) and 16±17 mmHg (DBP). Daytime and night-time correlations and mean difference were, day: SBP (r = 0.92, p<0.001), -1±13 mmHg; DBP (r = 0.44, p = 0.089), 18±21 mmHg; night: SBP (r = 0.66, p = 0.007), 6±22 mmHg; DBP (r = 0.64, p = 0.010); 15±13 mmHg. Over 24 hours, the total number of successful readings from the tonometric device was 52% less than that from the brachial cuff devices. The average correlation between SBP and DBP using only cuff readings was 0.29±0.40 (range -0.47 to 0.86). The average correlation between SBP and DBP for the tonometric device was 0.99±0.01 (range 0.97 to 1.00). Conclusions: The cuffless tonometric method employed in the BPro device enables unobtrusive monitoring of BP. In comparison to conventional cuff ABPM devices, the BPro device showed low mean differences for SBP but large differences in DBP in both day and night measurements with consistently low precision. The large differences for DBP may be due to the high correlation between tonometric DBP and SBP, suggesting that waveform features are used for SBP estimation only, from which DBP is directly calculated.

Assessment of remote ischemic conditioning delivery with optical sensor in acute ischemic stroke: Randomised clinical trial protocol.

Remote ischemic conditioning (RIC) is delivered by a blood pressure cuff over the limb, raising pressure 50 mmHg above the systolic blood pressure, to a maximum of 200 mmHg. The cuff is inflated for five minutes and then deflated for five minutes in a sequential ischemia-reperfusion cycle 4-5 times per session. Elevated pressure in the limb may be associated with discomfort and consequently reduced compliance. Continuous assessment of relative blood concentration and oxygenation with a tissue reflectance spectroscopy (a type of optical sensor device) placed over the forearm during the RIC sessions of the arm will allow us to observe the effect of inflation and deflation of the pressure cuff. We hypothesize, in patients with acute ischemic stroke (AIS) and small vessel disease, RIC delivered together with a tissue reflectance sensor will be feasible. The study is a prospective, single-center, randomized control trial testing the feasibility of the device. Patients with AIS within 7 days from symptoms onset; who also have small vessel disease will be randomized 2:1 to intervention or sham control arms. All patients randomized to the intervention arm will receive 5 cycles of ischemia/reperfusion in the non-paralyzed upper limb with a tissue reflectance sensor and patients in the sham control arm will receive pressure by keeping the cuff pressure at 30 mmHg for 5 minutes. A total of 51 patients will be randomized, 17 in the sham control arm and 34 in the intervention arm. The primary outcome measure will be the feasibility of RIC delivered for 7 days or at the time of discharge. The secondary device-related outcome measures are fidelity of RIC delivery and the completion rate of intervention. The secondary clinical outcome includes a modified Rankin scale, recurrent stroke and cognitive assessment at 90 days. RIC delivery together with a tissue reflectance sensor will allow insight into the blood concentration and blood oxygenation changes in the skin. This will allow individualized delivery of the RIC and improve compliance. ClinicalTrials.gov Identifier: NCT05408130, June 7, 2022.

Hemodynamic responses to oscillatory thigh cuff inflations

Background. In the clinical setting, individuals have varying tolerance to hypovolemia induced by blood loss. Experimental generation of 0.1 Hz oscillations (~10-s cycle) in arterial pressure and cerebral blood flow via oscillatory lower body negative pressure (OLBNP) increases tolerance to this simulated hemorrhage, and protects cerebral tissue oxygenation. However, use of OLBNP as a method of inducing hemodynamic oscillations in the clinical setting is limited as: 1) it is a large and cumbersome technique, and; 2) it induces central hypovolemia, which would only worsen the magnitude of hemorrhage. In this study we evaluated a more clinically applicable method of inducing 0.1 Hz oscillations in arterial pressure and cerebral blood flow, using intermittent inflation of bilateral thigh cuffs. We hypothesized that the amplitude of arterial pressure and cerebral blood flow oscillations at 0.1 Hz would increase in response to repeated thigh cuff inflations at 0.1 Hz when compared with a baseline control condition. Methods. Ten healthy human subjects were tested (6 male, 4 female; 26.8 ± 4.1 y). Middle cerebral artery velocity (MCAv) was measured via transcranial doppler ultrasound, arterial pressure was measured via finger photoplethysmography, and end tidal CO2 (etCO2) was measured via capnography. Following a 10-min baseline period, intermittent thigh cuff inflations at 0.1 Hz and 230 mmHg (5-s inflation, 5-s deflation) were performed for 10-min (“oscillations”). 0.1 Hz oscillatory amplitude of mean arterial pressure and mean MCAv were quantified using Fast Fourier transformation during the last 5-min of baseline and the oscillatory period, and compared via two-tailed paired t-tests. Results. The amplitude of 0.1 Hz oscillations increased during the oscillatory period vs. baseline for mean arterial pressure (baseline: 1.7 ± 1.0 mmHg2 vs. oscillations: 9.0 ± 6.2 mmHg2; P = 0.004) and mean MCAv (baseline: 1.1 ± 0.6 (cm/s)2 vs. oscillations: 3.4 ± 3.1 (cm/s)2; P = 0.04). Absolute mean arterial pressure was similar between baseline and the oscillatory period (baseline: 97.2 ± 8.1 mmHg vs. oscillations: 99.1 ± 15.0 mmHg; P = 0.54), but absolute mean MCAv was lower during the oscillatory period (baseline: 61.7 ± 14.6 cm/s vs. oscillations: 53.2 ± 13.1 cm/s; P = 0.02). This reduction in mean MCAv was most likely due to hypocapnia (indexed by etCO2) induced by pacing the breathing of all subjects at ≥10 breaths/min (baseline: 33.2 ± 4.8 mmHg vs. oscillations 27.2 ± 4.5 mmHg; P = 0.005). Conclusions. Intermittent thigh cuff inflations at 0.1 Hz induced 0.1 Hz oscillations in both arterial pressure and cerebral blood flow when compared to baseline. These findings indicate that intermittent thigh cuff inflations could be developed as a method to induce pulsatile perfusion as a potential new therapy for individuals experiencing major blood loss. American Heart Association (Transformational Project Award) #19TPA34910073 and UNTHSC Physiology and Anatomy Seed Grant 2021 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Electrical auricular tragus stimulation induces release of circulating cardioprotective factors in healthy human volunteers.

Background: Vagal activation during remote ischemic conditioning (RIC) with subsequent release of cardioprotective factors from the spleen into the circulation reduces infarct size. These humoral cardioprotective factors can be transferred with plasma-dialysate from donors undergoing RIC to isolated recipient hearts where they reduce infarct size. Electrical auricular tragus stimulation (ATS) has been demonstrated to reduce the cardiac injury biomarker release and the frequency of ventricular arrhythmias and to improve contractile function in patients with acute myocardial infarction. Aim: To determine whether ATS, as RIC, induces release of cardioprotective factors into the circulation. Methods: Healthy volunteers (3 females, 7 males, 26±5 years) were randomized to receive ATS or RIC, respectively, with an interval of at least two weeks between protocols. ATS was induced by bipolar electrical rectangular pulses of 200μs width at a frequency of 30 Hz (Curamed TEN630, CURAmed, Shenzen Dongdixin Technology, Shenzhen, China). The amplitude (5.5 ± 0.81 mA) was set for each volunteer to not be perceived as uncomfortable over the total stimulation period. A microprocessor-controlled circuit periodically interrupted the stimulation signal after 5 s of stimulation for 5 s. ATS was continued over 30 min. RIC served as a reference to induce the release of cardioprotective factors by 3 x 5 min blood pressure cuff inflation at 200 mmHg on the left upper arm/ 5 min deflation. Venous blood samples were taken before and 60 min after ATS or RIC, respectively, and used to prepare plasma-dialysates (1:10 dialysis against buffer for 24 h, cut-off 12-14 kDa). Male Lewis rats were sacrificed and their hearts isolated and perfused at constant pressure with buffer. Plasma-dialysates from samples taken before and 60 min after ATS or RIC, respectively, were infused for 8 min followed by 2 min washout into rat hearts before global 30 min ischemia/ 120 min reperfusion. Infarct size was demarcated by triphenyl tetrazolium chloride staining and calculated as percent of ventricular mass. Results: With infusion of plasma-dialysate before ATS infarct size was 30.9±4.5% of ventricular mass and not different from that with infusion of plasma-dialysate before RIC (35.8±5.8%). Infusion of plasma-dialysate after ATS reduced infarct size to 18.3±3.9%. This cardioprotective effect was similar to that seen with infusion of plasma-dialysate after RIC (20.1±3.5%). Conclusion: ATS induces release of cardioprotective factors into the circulation of healthy volunteers. Plasma-dialysates after ATS or RIC, respectively, reduce myocardial infarct size by the same magnitude in ex vivo isolated perfused rat hearts with global ischemia/ reperfusion. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Rapid onset vasodilation in response to forearm muscle contraction in Hispanic American and Caucasian American Adults

Hispanic Americans (HA) are the fastest growing ethnic populations in the U.S., estimated to double in the next four decades. According to NHANES 2013-2016 data, prevalence of type 2 diabetes (T2D) is 15.1% in HA men and 14.1% in HA women, compared to 9.4 and 7.3% in non-Hispanic Caucasian American (CA) men and women, respectively. Even HA children have a 5-fold higher rate of T2D compared to their age-matched CA counterparts. Impaired vascular function is a hallmark of T2D however, limited number of studies have investigated the effect of ethnicity on vascular function at rest and during exercise. To our knowledge, only one study has reported a higher flow-mediated dilation at rest in healthy HA compared to CA adults. Hence, the purpose of this study was to investigate the rapid onset vasodilation in response to a single muscle contraction of the forearm at progressively increasing intensity (20, 40, and 60% of maximum voluntary contraction (MVC)) in young, healthy HA compared to age- and weight-matched CA individuals. A single muscle contraction model was chosen to isolate the robust local vasodilatory responsiveness of the vasculature without increases in sympathetic nerve activity or large hemodynamic changes. We hypothesized that HA would demonstrate an attenuated forearm vascular conductance (FVC) and forearm blood flow (FBF) in response to skeletal muscle contractions, compared to CA group. Young, healthy HA (n=4) and CA (n=4) adults performed skeletal muscle contractions at 20%, 40 % and 60% of their maximum voluntary contraction (MVC). To isolate the effect of mechanical compression during muscle contractions, FBF and FVC responses to a brachial cuff inflation were also measured. Heart rate (ECG), mean arterial pressure (MAP; finger photoplethysmography) and forearm blood flow (FBF; duplex Doppler ultrasound) were measured. FVC was calculated as FBF/MAP. Baseline FBF (CA: 115.21 ± 48.9 and HA: 68.89 ± 21.9 ml/min; p=0.27), MAP (CA: 82 ± 7.48 and HA: 81 ± 2.87 mmHg; p=0.77), FVC (p=0.15), and MVCs (CA: 67 ± 26.8 and HA: 70 ± 7.4 kg; p=0.82) were similar between the groups. Following single muscle contractions, both groups exhibited an intensity dependent increase in FVC and FBF, however, there was no difference between HA and CA groups. For instance, following muscle contraction at 40% MVC, peak FVC (%Δ) was 251% ± 46.35 in HA and 189% ± 34.98 in CA (race effect p = 0.23, time effect = 0.01, interaction p = 0.029). Similarly, peak %Δ FBF or %Δ FVC following 60% contractions were similar between the groups (FVC: 327% ± 84.36 in HA vs. 286% ± 74.45 in CA (race effect p=0.62, time effect p<0.01, interaction effect p=0.01)). Both groups exhibited a similar response to brachial cuff inflation for peak FVC (p=0.21) and peak FBF (p=0.30). Our preliminary findings indicate that HA have a preserved rapid onset vasodilation in response to a single forearm contraction when compared to CA adults. Supported by Kinesiology and Health Education UT Austin Start-up Account 19-2635-91 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of remote ischemic conditioning on the immune-inflammatory profile in patients with traumatic hemorrhagic shock in a randomized controlled trial

Resuscitation induced ischemia/reperfusion predisposes trauma patients to systemic inflammation and organ dysfunction. We investigated the effect of remote ischemic conditioning (RIC), a treatment shown to prevent ischemia/reperfusion injury in experimental models of hemorrhagic shock/resuscitation, on the systemic immune-inflammatory profile in trauma patients in a randomized trial. We conducted a prospective, single-centre, double-blind, randomized, controlled trial involving trauma patients sustaining blunt or penetrating trauma in hemorrhagic shock admitted to a Level 1 trauma centre. Patients were randomized to receive RIC (four cycles of 5-min pressure cuff inflation at 250 mmHg and deflation on the thigh) or a Sham intervention. The primary outcomes were neutrophil oxidative burst activity, cellular adhesion molecule expression, and plasma levels of myeloperoxidase, cytokines and chemokines in peripheral blood samples, drawn at admission (pre-intervention), 1 h, 3 h, and 24 h post-admission. Secondary outcomes included ventilator, ICU and hospital free days, incidence of nosocomial infections, 24 h and 28 day mortality. 50 eligible patients were randomized; of which 21 in the Sham group and 18 in the RIC group were included in the full analysis. No treatment effect was observed between Sham and RIC groups for neutrophil oxidative burst activity, adhesion molecule expression, and plasma levels of myeloperoxidase and cytokines. RIC prevented significant increases in Th2 chemokines TARC/CCL17 (P < 0.01) and MDC/CCL22 (P < 0.05) at 24 h post-intervention in comparison to the Sham group. Secondary clinical outcomes were not different between groups. No adverse events in relation to the RIC intervention were observed. Administration of RIC was safe and did not adversely affect clinical outcomes. While trauma itself modified several immunoregulatory markers, RIC failed to alter expression of the majority of markers. However, RIC may influence Th2 chemokine expression in the post resuscitation period. Further investigation into the immunomodulatory effects of RIC in traumatic injuries and their impact on clinical outcomes is warranted.ClinicalTrials.gov number: NCT02071290.

Efficacy of an Automated Secretion Removal Technology at Different Inspiratory Pressures.

Endotracheal suctioning is resource demanding, causes patient discomfort, and is associated with adverse effects. A new artificial cough method has been developed for automated secretion removal by using rapid deflation and inflation of the endotracheal tube cuff during the inspiratory phase of mechanical ventilation. This method has been evaluated in a bench model and in animals but not in human subjects. The aim of this study was to investigate whether this method can remove the need for endotracheal suctioning in subjects and whether this is dependent on ventilator settings. This prospective, non-controlled study recruited 20 subjects on invasive mechanical ventilation. On the clinical need for endotracheal suctioning, the automatic cough procedure was applied 3 times over 30 s, with this repeated at higher ventilatory pressure and lower respiratory frequency if considered unsuccessful. Success was determined by removal of the clinical need for suctioning. Subject safety and comfort was measured by using the Critical-Care Pain Observation Tool before and after the procedure, and negative effects were recorded. To assess intra-subject variability, the procedure was performed on 3 different occasions for each subject. The procedure was successful in 18 of 20 subjects (90%), with mean subject success rates of 53% at low settings (peak inspiratory pressure 21.8 ± 3.8 cm H2O) and 83% at high settings (peak inspiratory pressure 25.6 ± 3.6 cm H2O). The Critical-Care Pain Observation Tool category remained unchanged in 30 procedures (77%), improved in 7 (18%), and deteriorated in 2 (5%). This study illustrated the potential for significant reduction in the clinical need for endotracheal suctioning after the use of an automated artificial cough procedure at both low and high peak inspiratory pressures, and that was well tolerated.

Effects of Blood Flow Restriction on Pain and Muscle Thickness Following Tendinopathy: A Case Study

Introduction: Blood flow restriction (BFR) training, in which an inflatable cuff partially occludes blood flow around the proximal portion of a limb, coupled with low-load resistance exercise (LLRE) has resulted in gains comparable with traditional progressive resistive exercise in healthy populations. The use of BFR with LLRE may help people with supraspinatus tendinopathy through proximal effects to improve strength and muscle size. The purpose of this case report is to describe the proximal effect of the LLRE+BFR program on a patient with supraspinatus tendinopathy.&#x0D; Materials and Methods: The patient was a 40-year-old man with a history of shoulder pain and weakness for the past months. He received an LLRE+BFR program for his right shoulder including rotator cuff and scapular strengthening exercises and lower limbs aerobic exercises based on protocols of strengthening and aerobic exercises of BFR. Outcomes measured at baseline and 4 weeks included the 4 items: 1) Strength of supraspinatus muscle and four scapular stabilizer muscles including serratus anterior strength, middle trapezius strength, and lower trapezius strength by dynamometer, 2) supraspinatus thickness by ultrasound, 3) pain pressure threshold of supraspinatus and deltoid muscles by algometer, and 4) pain reported bay in each session based on pain numeric scale.&#x0D; Results: After 6 weeks, the strength of supraspinatus and scapular stabilizers except for the lower trapezius increased. The supraspinatus thickness and pain pressure threshold in the supraspinatus and deltoid muscle also increased after 4 weeks. The mean of pain reported by the patient based on the pain numeric scale before and after each session was also decreased.&#x0D; Conclusion: The patient had measurable improvements following the use of an LLRE+BFR program. LLRE+BFR program may be an option for strength training in people with supraspinatus tendinopathy; however, more research is needed to determine effectiveness across the population of people with supraspinatus tendinopathy.&#x0D;

Efficacy of Laryngeal Mask Airway Impregnation with Diltiazem Gel on Hemodynamic Changes in Patients with Hypertension Undergoing Phacoemulsification Surgery: A Randomized Clinical Trial

Background: Airway control problems are among the most prevalent causes of anesthesia-related mortality and morbidity. Some devices provide patients with adequate oxygen supply and ventilation during surgery by creating a safe airway in anesthetized patients. One of these devices is the laryngeal mask airway (LMA). The compression and painful stimuli following the LMA cuff inflation can lead to hemodynamic changes. Diltiazem gel is used in the control and treatment of hypertension (HTN) and heart arrhythmia and is absorbed through the tracheal mucosa. Objectives: By assuming that diltiazem gel is superior to other drugs used to prevent arrhythmias and hemodynamic changes during surgery, this study aimed to evaluate the effect of LMA impregnation with diltiazem gel, compared to lubricant gel. Methods: This study was conducted as a double-blind, randomized clinical trial on 80 participants with HTN who were candidates for phacoemulsification (phaco) surgery in Imam Khomeini Hospital, Kermanshah, Iran. The participants were assigned to an intervention (LMA impregnated with diltiazem gel) and a control group (LMA impregnated with lubricant gel) through the block random method in the form of 40 blocks of 2 using a random-numbers table. Hemodynamic changes (systolic and diastolic blood pressure and heart rate) were measured before, immediately after, 5 min, and 15 min after intubation, during surgery every 15 min, upon entering the recovery unit, and 15 and 30 min after entering the recovery unit. Results: The mean systolic and diastolic blood pressure in the intervention group showed a significant decrease, compared to that in the control group. A significant difference was also observed in the mean heart rate difference between the two study groups, but only at the beginning of the study (P&lt;0.05). Additionally, according to the results of repeated measures analysis of variance, the mean of the measured variables showed a significant difference at different measurement times in the intervention group (P&lt;0.05). Conclusion: The findings supported the effectiveness of diltiazem gel in reducing blood pressure, especially in the final stages of surgery, decreasing the number of premature ventricular contractions, and controlling normal breathing. Therefore, specialists and surgeons can use diltiazem gel to control the hemodynamic status of patients.

Evaluation of large animal models for preclinical studies of heart failure with preserved ejection fraction using clinical score systems.

Heart failure with preserved ejection fraction (HFpEF) is characterized by a complex, heterogeneous spectrum of pathologic features combined with average left ventricular volume and diastolic dysfunction. HFpEF is a significant public health problem associated with high morbidity and mortality rates. Currently, effective treatments for HFpEF represent the greatest unmet need in cardiovascular medicine. A lack of an efficient preclinical model has hampered the development of new devices and medications for HFpEF. Because large animal models have similar physiologic traits as humans and appropriate organ sizes, they are the best option for limiting practical constraints. HFpEF is a highly integrated, multiorgan, systemic disorder requiring a multipronged investigative approach. Here, we review the large animal models of HFpEF reported to date and describe the methods that have been used to create HFpEF, including surgery-induced pressure overloading, medicine-induced pressure overloading, and diet-induced metabolic syndrome. In addition, for the first time to our knowledge, we use two established clinical HFpEF algorithms (HFA-PEFF and H2FPEF scores) to evaluate the currently available large animal models. We also discuss new technologies, such as continuous remote pressure monitors and inflatable aortic cuffs, as well as how the models could be improved. Based on current progress and our own experience, we believe an efficient large animal model of HFpEF should simultaneously encompass multiple pathophysiologic factors, along with multiorgan dysfunction. This could be fully evaluated through available methods (imaging, blood work). Although many models have been studied, only a few studies completely meet clinical score standards. Therefore, it is critical to address the deficiencies of each model and incorporate novel techniques to establish a more reliable model, which will help facilitate the understanding of HFpEF mechanisms and the development of a treatment.

Remote Ischemic Conditioning in Pediatric Cancer Patients Receiving Anthracycline Chemotherapy: A Sham-Controlled Single-Blind Randomized Trial

BackgroundAnthracycline cardiotoxicity is a concern in survivors of childhood cancers. Recent evidence suggests that remote ischemic conditioning (RIC) may offer myocardial protection. ObjectivesThis randomized sham-controlled single-blind study tested the hypothesis that RIC may reduce myocardial injury in pediatric cancer patients receiving anthracycline chemotherapy. MethodsWe performed a phase 2 sham-controlled single-blind randomized controlled trial to determine the impact of RIC on myocardial injury in pediatric cancer patients receiving anthracycline-based chemotherapy. Patients were randomized to receive RIC (3 cycles of 5-minute inflation of a blood pressure cuff placed over 1 limb to 15 mm Hg above systolic pressure) or sham intervention. The intervention was applied within 60 minutes before initiation of the first dose and before up to 4 cycles of anthracycline therapy. The primary outcome was the plasma high-sensitivity cardiac troponin T (hs-cTnT) level. The secondary outcome measures included echocardiographic indexes of left ventricular systolic and diastolic function and the occurrence of cardiovascular events. ResultsA total of 68 children 10.9 ± 3.9 years of age were randomized to receive RIC (n = 34) or sham (n = 34) intervention. Plasma levels of hs-cTnT showed a progressive increase across time points in the RIC (P < 0.001) and sham (P < 0.001) groups. At each of the time points, there were no significant differences in hs-cTnT levels or LV tissue Doppler and strain parameters between the 2 groups (all P > 0.05). None of the patients developed heart failure or cardiac arrhythmias. ConclusionsRIC did not exhibit cardioprotective effects in childhood cancer patients receiving anthracycline-based chemotherapy. (Remote Ischaemic Preconditioning in Childhood Cancer [RIPC]; NCT03166813)

Ischemic Conditioning to Reduce Fatigue in Isometric Skeletal Muscle Contraction

Ischemic preconditioning (IPC) is a non-invasive protective maneuver that alternates short periods of occlusion and reperfusion of tissue blood flow. Given the heterogeneity in the magnitude and frequency of IPC-induced improvements in physical performance, here we aimed to investigate, in a well-controlled experimental set-up, the local effects of IPC in exposed muscles in terms of tissue oxygenation and muscle fatigue. Nineteen subjects were enrolled in one of the two groups, IPC (3 × 5/5 min right arm ischemia/reperfusion; cuff inflations 250 mmHg) and SHAM (3 × 5/5 min pseudo ischemia/reperfusion; 20 mmHg). The subjects performed a fatiguing contraction protocol before and 30 min after the IPC treatment, consisting of unilateral intermittent isometric elbow flexions (3 s ON/OFF, 80% of maximal voluntary contraction) until exhaustion. While muscle strength did not differ between groups, post- vs. pre-treatment endurance was significantly reduced in the SHAM group (4.1 ± 1.9 vs. 6.4 ± 3.1 repetitions until exhaustion, p < 0.05) but maintained in IPC (7.3 ± 2.0 vs. 7.1 ± 4.3, n.s.). The decrease in tissue oxygenation and the increase in deoxygenated hemoglobin were significantly reduced post- vs. pre-IPC (p < 0.05), but not post- vs. pre-SHAM. The results suggest that IPC delays the onset of fatigue likely through improved metabolic efficiency of muscles.

Negative intracuff pressure inside the deflated cuff of an endotracheal tube.

Dear Editor, Inflation and deflation of the cuff of an endotracheal tube (ETT) is a routine part of airway management. Inflation of the cuff ensures a seal that enables intermittent positive pressure ventilation and provides safety from aspiration of gastric contents.[1] Like inflation, deflation of the ETT cuff carries its own importance prior to extubation and during nasotracheal intubation. Quantification of cuff inflation is translated as positive intracuff pressure, which is widely measured using a cuff manometer.[2] However, there is no provision to quantify the intracuff pressure of a deflated cuff. We report a case indicating negative intracuff pressure inside a deflated cuff. A 26-year-old gentleman who had a history of road traffic accident three days back, presented with restricted mouth opening. The patient was diagnosed with a fractured mandible and was scheduled for fixation under general anaesthesia. The pre-anaesthetic check-up was within normal limits. Airway examination revealed a mouth opening of around 3 cm and a Modified Mallampati score of 3. The airway management plan was nasotracheal intubation using McGrath video laryngoscope. On the day of the surgery and after the induction of general anaesthesia, an armoured ETT of 7.0 mm internal diameter was introduced through the right nostril after deflating the cuff. After inserting around 10 cm of the ETT, the McGrath video laryngoscope size 3 was introduced in the oral cavity. As it was further advanced looking at the video screen, a pool of blood was observed in the oropharynx along with the ETT. The oropharynx was suctioned and as the vocal cords became visible, the ETT was inserted through the larynx and into the trachea. As the pilot balloon was picked up to inflate the cuff, blood was noticed in the pilot balloon and the inflation line [Figure 1]. Furthermore, we failed to inflate the cuff. The cuff was considered ruptured and the ETT was replaced. The inference was that the simultaneous rupturing of the cuff and the negative pressure contained inside the deflated cuff caused in-drawing of the surrounding blood into the inflation line and the pilot balloon.Figure 1: Blood inside the inflation line and pilot balloon of the endotracheal tubeIn a model experiment, the deflated cuff was ruptured in a bowl of coloured dye, and there was immediate siphoning of dye in the inflation line and the pilot balloon. This case and the experimental model highlighted that an unquantified negative pressure is contained inside the deflated cuff, contrary to the expected zero or atmospheric pressure. Any breach in the integrity of the cuff system acquired during the procedure of endotracheal intubation is unidentified until the attempted inflation of the cuff. The unusual observation of blood in the inflation line in the reported case indicated the breach. The clinical utility of this unique observation requires further exploration and study. Identical to the negative pressure test of the low-pressure system of an anaesthesia machine, a negative pressure test can be designed to confirm the integrity of the ETT cuff system prior to tracheal intubation. A conventional test for the cuff system needs inflation of the cuff system, which mandates deflation of the cuff prior to intubation: this makes it a multi-step process.[3,4] A negative pressure test, however, consists of a single step of cuff deflation and the deflated cuff for a pre-defined time period confirms integrity of the cuff system. Furthermore, ETTs can be factory supplied with a specified negative intracuff pressure rather than zero pressure. This practice bypasses the testing of the cuff system and requires only a mere visual inspection of the collapsed cuff through the transparent packing. Unlike cuff inflation, deflation of the cuff has not been not standardised. It is by tactile perception that cuffs are deflated before each extubation or prior to nasotracheal intubation. A measuring device can be designed to estimate the negative pressure inside the cuff system with a fixed standard rather than just the binary of yes or no. To conclude, this novel entity can hold a prominent place in the practice of anaesthesiology and opens up an arena of further research activity. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patient understands that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Effect of Fixed Tracheal Cuff Volume vs Fixed Tracheal Cuff Pressure on Hemodynamic Parameters and Postoperative Airway Complications, A Prospective Randomized Control Trial in a Tertiary Care Hospital

Background: The current study is aimed to compare the effect of fixed cuff volume and fixed cuff pressure technique on hemodynamic parameters and on postoperative complications.&#x0D; Methods: The prospective, randomised, controlled study was conducted in a tertiary care hospital with 100 patients aged between 18 to 60 yrs. The patients who are undergoing for elective surgeries under general anaesthesia were enrolled after obtaining ethical committee approval. Patients were randomized based on computer generated random numbers into two groups, fixed volume (7ml) group (group V, n-50) and fixed cuff pressure group (group P, n-50). The ETT cuff was filled with 7 ml of air in the fixed volume technique, and in the fixed cuff pressure group -cuff pressure was maintained at 20 cmH2O, after intubation. Tracheal tube cuff pressures were measured by AMBU cuff pressure gauge manometer. Hemodynamic parameters SBP, DBP, MAP and PR were noted at the time of cuff inflation, after extubation in the both the groups. Post-operative sore throat, hoarseness and cough was assessed at the time of extubation in the both the groups.&#x0D; Results: Mean age in both the groups was 41 years. Statistical significance (P&lt; 0.0001) was observed in Group P in systolic blood pressure (SBP), diastolic blood pressure (DBP), MAP, HR whereas no significance was seen in group V. The percentage of post-operative complications like hoarseness, cough, sore throat, and dysphagia were seen to be less in group P when compared to group V.&#x0D; Conclusion: With present data we could conclude that the fixed minimal cuff pressure (20 mm H2O) is an ideal and reliable technique in reducing the post-operative complications along with maintenance of hemodynamic parameters.&#x0D;

Investigating the Ischaemic Phase of Skin NADH Fluorescence Dynamics in Recently Diagnosed Primary Hypertension: A Time Series Analysis.

The reduced form of nicotinamide adenine dinucleotide (NADH) is crucial in cellular metabolism. During hypoxia, NADH accumulation results from anaerobic cytoplasmic glycolysis and impaired mitochondrial function. This study aimed to compare the dynamic changes in the 460-nm forearm skin fluorescence, which reflects cellular NADH content, during transient ischaemia between healthy individuals and patients with newly diagnosed, untreated essential hypertension (HA). Sixteen healthy volunteers and sixty-five patients with HA underwent non-invasive measurement of forearm skin NADH content using the Flow Mediated Skin Fluorescence (FMSF) method at rest and during a 100-s transient ischaemia induced by inflation of the brachial cuff. The fluorescent signal was sampled at 25 Hz. All samples were normalised to the end of the ischaemic phase, which is the most stable phase of the whole recording. Slope values of 1 s linear regressions were determined for every 25-sample neighbouring set. The 1-s slopes in the early phase of skin ischaemia, indicating quicker hypoxia-induced NADH accumulation in skin, were significantly higher in patients with HA than in healthy individuals. These findings suggest that some protecting mechanisms postponing the early consequences of early cellular hypoxia and premature NADH accumulation during skin ischaemia are impaired in patients with untreated HA. Further studies are needed to investigate this phenomenon.

Cuff Inflation for Correct Endotracheal Tube Alignment With Glottis While Using C-MAC Videolaryngoscope D Blade in Patients With Restricted Mouth Opening.

Department of Anaesthesiology, Amrita Institute of Medical Sciences, Amrita VishwaVidyapeetham, Kochi, Kerala, India Address for correspondence: Dr. Sunil Rajan, Department of Anaesthesiology, Amrita Institute of Medical Sciences, Kochi - 682 041, Kerala, India. E-mail: [email protected] Received July 30, 2021 Accepted December 15, 2021 This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 4.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Airway Management During Diagnostic Laparoscopic Surgery: A Comparison of I-Gel and Proseal Laryngeal Mask Airway.

Supraglottic airway devices (SADs) may be used during laparoscopic procedures in place of the often utilised endotracheal tube. The Proseal laryngeal mask airway (PLMA) is designed with an inflatable cuff, which provides an excellent oropharyngeal seal, and the I-gel is a newer SAD designed with a softer and noninflatable cuff and sharing similar features with PLMA. This study compared the ease of insertion, haemodynamic and ventilatory parameters as well as morbidities associated with these SADs when used for airway management during diagnostic laparoscopic procedures. Eighty American Society of Anaesthesiologist I and II patients aged 18-60 years undergoing diagnostic laparoscopic surgery under controlled ventilation had either I-gel or PLMA used for airway management. Anaesthesia was induced with standard dose of propofol, patient received atracurium, fentanyl and the SAD inserted. Pulse oximetry, capnography, noninvasive blood pressure, oropharyngeal leak pressure (OLP), and evidence of pharyngolaryngeal morbidity were assessed. Data were analysed using the Statistical Package for Social Sciences version 21.0. The quantitative variables were analysed using the Student's t test and the qualitative using the Chi-square test. A P value of less than 0.05 was considered significant. The success rates at first insertion for I-gel and PLMA were 95% and 80%, respectively (P = 0.04). The mean changes in mean arterial pressure following insertion were 9.6 mmHg (±4.7) and 10.6 mmHg (±8) for I-gel and PLMA, respectively (P = 0.02). The OLP during insufflation was higher in the PLMA (35.8 cmH2O) than in the I-gel group (27.9 cmH2O) (P = 0.57). In the I-gel group, 12.5% of the patients had oropharyngeal morbidities compared with 37.5% in the PLMA group (P = 0.009). Both I-gel and PLMA provide optimal ventilation during abdominal insufflation, with PLMA providing a better oropharyngeal seal, whereas I-gel has a better haemodynamic profile.

Disposable Airway Pressure Manometers for Endotracheal Tube Cuff Inflation.

This study aimed to assess the performance, accuracy, precision and repeatability of two single-use airway pressure manometers as a cost-effective alternative for inflation of endotracheal tubes with high-volume, low-pressure cuffs. The manometers were tested in a bench top model against a U-tube manometer. Eighteen units of each device were tested. Three consecutive measurements were performed at pressures of 20, 25 and 30 cmH2O each. The mean ± SD of the recorded pressures and maximum deviation from the target pressures were calculated for each device and each target pressure. For device A, the mean ± SD pressures were 19.6 ± 0.7, 23.6 ± 0.8 and 28.3 ± 0.8 cmH2O; for device B, the mean ± SD pressures were 19.3 ± 0.6, 24.3 ± 0.9 and 29.2 ± 0.67 cmH2O for target pressures of 20, 25 and 30 cmH2O, respectively. The bias for device A was -0.4, -1.4, and -1.7 cmH2O and for device B, -0.7, -0.7, and -0.8 cmH2O for target pressures of 20, 25, and 30 cmH2O, respectively. Both devices showed results comparable to those reported for commercial cuff manometers. They represent inexpensive tools that provide clinically sufficient accuracy, precision and repeatability for ETT cuff inflation between pressures of 20 and 30 cmH2O.