Invasive Blood Pressure Measurements Research Articles

LVSP and LBBP result in similar or improved LV synchrony and hemodynamics compared to biventricular pacing

Abstract Background The effect of left ventricular myocardial septal pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and LV hemodynamics is poorly understood in unselected cardiac resynchronization therapy (CRT) patients. Aim To investigate the impact of LBBP and LVSP on ultra-high-frequency ECG (UHF-ECG) ventricular synchrony and hemodynamics in CRT patients. Methods In consecutive CRT patients with LBBB, ventricular synchrony was assessed using UHF-ECG. LV hemodynamics was assessed using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and biventricular pacing (BVP). LV synchrony was assessed by LV lateral wall delay (LVLWd) from the first to the last from V5-V8 activations. Hemodynamic effects were expressed as relative changes in systolic blood pressure. Results Thirty patients with an LVEF of 29 ± 6% and mean QRSd of 169 ± 24 ms were included. Twenty had non-ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LVLWd than BVP (-9 ms (-16; -4), p = 0.004); the difference between LVSP and BVP was not significant (-4 ms (-10;2), p = 0.2). LBBP was associated with higher systolic blood pressure than BVP (4% (2; 5) p < 0.001), while LVSP was not (1% (1; 2), p = 0.1. LV hemodynamic improvements during LBBP and LVSP vs. BVP were more pronounced in non-ischemic than ischemic patients. Conclusion The differences in ventricular synchrony between LBBP, LVSP, and BVP were demonstrated using UHF-ECG but not QRSd. LBBP, but not LVSP, was associated with better LV synchrony and hemodynamics than BVP.Local activation times in V1–V8Ventricular dyssynchrony and hemodynamic

LVSP and LBBP Result in Similar or Improved LV Synchrony and Hemodynamics Compared to BVP

BackgroundThe effect of left ventricular septal myocardial pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and left ventricular (LV) hemodynamic status is poorly understood. ObjectivesThe aim of this study was to investigate the impact of LVSP and LBBP vs biventricular pacing (BVP) on ventricular electrical synchrony and hemodynamic status in cardiac resynchronization therapy patients. MethodsIn cardiac resynchronization therapy candidates with LV conduction disease, ventricular synchrony was assessed by measuring QRS duration (QRSd) and using ultra-high-frequency electrocardiography. LV electrical dyssynchrony was assessed as the difference between the first activation in leads V1 to V8 to the last from leads V4 to V8. LV hemodynamic status was estimated using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and BVP. ResultsA total of 35 patients with a mean LV ejection fraction of 29% and a mean QRSd of 168 ± 24 ms were included. Thirteen had ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LV electrical dyssynchrony than BVP (−10 ms; 95% CI: −16 to −4 ms; P = 0.001); the difference between LVSP and BVP was not significant (−5 ms; 95% CI: −12 to 1 ms; P = 0.10). LBBP was associated with higher systolic blood pressure than BVP (4%; 95% CI: 2% to 5%; P < 0.001), whereas LVSP was not (1%; 95% CI: 0% to 2%; P = 0.10). Hemodynamic differences during LBBP and LVSP vs BVP were more pronounced in nonischemic than ischemic patients. ConclusionsUltra-high-frequency electrocardiography allowed the documentation of differences in LV synchrony between LBBP, LVSP, and BVP, which were not observed by measuring QRSd. LVSP provided the same LV synchrony and hemodynamic status as BVP, while LBBP was better than BVP in both.

Short-Chain Fatty Acid Butyrate Is an Inotropic Agent With Vasorelaxant and Cardioprotective Properties.

The heart can metabolize the microbiota-derived short-chain fatty acid butyrate. Butyrate may have beneficial effects in heart failure, but the underlying mechanisms are unknown. We tested the hypothesis that butyrate elevates cardiac output by mechanisms involving direct stimulation of cardiac contractility and vasorelaxation in rats. We examined the effects of butyrate on (1) invivo hemodynamics using parallel echocardiographic and invasive blood pressure measurements, (2) isolated perfused hearts in Langendorff systems under physiological conditions and after ischemia and reperfusion, and (3) isolated coronary arteries mounted in isometric wire myographs. We tested Na-butyrate added to injection solutions or physiological buffers and compared its effects with equimolar doses of NaCl. Butyrate at plasma concentrations of 0.56 mM increased cardiac output by 48.8±14.9%, stroke volume by 38.5±12.1%, and left ventricular ejection fraction by 39.6±6.2%, and lowered systemic vascular resistance by 33.5±6.4% without affecting blood pressure or heart rate invivo. In the range between 0.1 and 5 mM, butyrate increased left ventricular systolic pressure by up to 23.7±3.4% in isolated perfused hearts and by 9.4±2.9% following ischemia and reperfusion, while reducing myocardial infarct size by 81.7±16.9%. Butyrate relaxed isolated coronary septal arteries concentration dependently with an EC50=0.57 mM (95% CI, 0.23-1.44). We conclude that butyrate elevates cardiac output through mechanisms involving increased cardiac contractility and vasorelaxation. This effect of butyrate was not associated with adverse myocardial injury in damaged hearts exposed to ischemia and reperfusion.

Asphyxial Circulatory Arrest with a Complex of Resuscitation Measures in an Experimental Model

The majority of asphyxial circulatory arrest (CA) models have a number of disadvantages, such as the lack of uniform criteria for fixing CA and recovery of spontaneous circulation, short duration of CA episode and limited volume of post-resuscitation intensive care, poor similarity with resuscitation measures in current clinical anesthesiology/intensive care settings.The aim of the study: to improve the experimental model of asphyxicial CA by standardizing experimental procedures and using a complex of resuscitation measures replicating current CA management in clinical anesthesiology-intensive care.Materials and methods. The experiments were conducted on 34 male Wistar rats, distributed into 2 groups: Group I included animals subjected to sham procedure (SP, N=12) and Group II – animals subjected to asphyxial circulatory arrest (CA, N=22) and subsequent resuscitation. Asphyxia in anesthetized rats was induced by rocuronium bromide injection, followed by recording of electrocardiogram (ECG), parameters of invasive blood pressure (BP) measurement and laser Doppler fluxmetry (LDF) to assess skin perfusion. CA episode was maintained for 2 min, followed by a series of resuscitation measures and intensive therapy for 2 h. Circulatory parameters (ECG, BP, LDF), gas composition and arterial blood acid-base state (ABS) dynamics were evaluated.Results. Monitored parameters were comparable in both groups at baseline after stabilization period. After exclusion criteria were applied 11 animals from SP group and 18 — from CA were included in the analysis. Tachycardia (heart rate, beats/min–1, SP vs CA) was documented in the CA group: 218 [205; 236] vs 286 [272; 305], P⩽0.0001), as well as recovery of skin perfusion to subnormal parameters in the first minutes after successful resuscitation. At minute 10 in the post-resuscitation period worsening of skin perfusion (M, perfusion units, SP vs CA): 14.7 [12.1; 16.5] vs 10.1 [7.0; 12.5], P=0.0014), and decompensated mixed acidosis (pH, SP vs CA): 7.42 [7.40; 7.43] vs 7.20 [7.13; 7.23], P⩽0.0001) were documented in the CA group, however BP values were comparable (BP, mmHg, SP vs CA): 60 [58; 72] vs 67 [62; 82], P=0.482). At minute 120 post-resuscitation and at the end of intensive care period, both groups demonstrated similar values of the monitored parameters. Three out of 18 animals in the CA group died after resuscitation.Conclusion. Electromechanical dissociation underlies CA in rats subjected to asphyxia. The use of LDF to assess peripheral blood flow makes it possible to standardize the severity of ischemic reperfusion injuries and improve reproducibility of the model. Series of resuscitation measures in experimental setting is justified from a bioethical point of view, and makes it possible to improve repeatability of preclinical research results in clinical practice.

Case Report: Sympathetic crashing acute pulmonary edema – only “NIV and nitroglycerin”?

Introduction An 84-year-old male patient alerted EMS because of severe dyspnea and subsequently presented with respiratory failure due to sympathetic crashing acute pulmonary edema (SCAPE.) The term SCAPE was coined outside Europe, with guidance on treatment only reflecting drugs available in the US and omitting potentially effective options, as highlighted in this report.[1] Diagnostic findings The patient presented sweating, pale and tachypneic with auscultatory crackles, radial pulse was palpable. He was able to follow commands, but unable to communicate verbally due to dyspnea. Initial SpO2 showed 80%, NIBP 185/105mmHg. The patient described sudden onset dyspnea as the only symptom. An ECG showed sinus tachycardia and LBBB (SGARBOSSA negative.) ABG showed hypoxemia and acidosis due to hypercapnia and lactatemia. Main diagnosis In absence of other causes for flash pulmonary edema, SCAPE was suspected. Therapeutic interventions The patient was supported in sitting position, oxygen applied, a total of 25mg urapidil and 7mg morphine administered intravenously, non-invasive ventilation (CPAP+ASB, PEEP 5mbar, ΔASB 5mbar) initiated and an arterial line placed for invasive blood pressure measurement and ABG. Outcome While RSI was considered multiple times, the patient improved rapidly during transport and a short NIV duration at the emergency department and was transferred to the ward without further interventions. Discussion With reducing afterload as main goal of pharmacological therapy, urapidil could be as effective as high-dose i.v. nitroglycerine, which is currently recommended.[2,3] While lacking the effect of venous vasodilation and thus not reducing preload, its effect on sympathetic tone via 5-HT1A-receptors supplemental to affecting arterial vasodilation via α-receptors might make it equally effective while being easier to administer. No data is available comparing urapidil to high-dose nitroglycerin, while it has proven more effective than low-dose nitroglycerin.[4]

MFAP4-Deficiency Aggravates Age-Induced Changes in Resistance Artery Structure, While Ameliorating Hypertension.

Abnormalities of resistance arteries may play essential roles in the pathophysiology of aging and hypertension. Deficiency of the vascular extracellular matrix protein MFAP4 (microfibrillar-associated protein 4) has previously been observed as protective against aberrant arterial remodeling. We hypothesized that MFAP4-deficiency would reduce age- and hypertension-dependent arterial changes in extracellular matrix composition and stiffening. Mesenteric arteries were isolated from old (20-23 months) littermate Mfap4+/+ and Mfap4-/- mice, and 2-photon excitation microscopy imaging was used to quantify elastin and collagen volumes and dimensions in the vascular wall. Ten-week-old littermate Mfap4+/+ and Mfap4-/- mice were subjected to 20 days of continuous Ang II (angiotensin II) infusion and hypertension was monitored using invasive blood pressure measurements. Arterial stiffness, responses to vascular constrictors, and myogenic tone were monitored using wire- or pressure myography. Collagen contents were assessed by Western blotting. MFAP4 deficiency significantly increased collagen volume and elastin fragmentation in aged mesenteric arteries without affecting arterial stiffness. MFAP4-deficient mice exhibited reduced diastolic pressure in Ang II-induced hypertension. There was no significant effect of MFAP4-deficiency on mesenteric artery structural remodeling or myogenic tone, although collagen content in mesenteric arteries was tendentially increased in hypertensive Mfap4+/+ mice relative to Mfap4-/- mice. Increased efficacy of vasoconstrictors (phenylephrine, thromboxane) and reduced stiffness were observed in Ang II-treated Mfap4-/- mouse mesenteric arteries in ex vivo myography recordings. MFAP4 deficiency reduces the elastin/collagen ratio in the aging resistance artery without affecting arterial stiffness. In contrast, MFAP4-deficiency reduces the stiffness of resistance arteries and ameliorates Ang II-induced hypertension.

Cardiovascular Protective Effect of Garcinia dulcis Flower Acetone Extract in 2-Kidney-1-Clip Hypertensive Rats.

Morelloflavone and camboginol are bioactive compounds purified from Garcinia dulcis (GD), which has anti-inflammatory and antihypertensive properties. The objective of this study was to examine the cardiovascular protective effect of GD flower acetone extract in 2-kidney-1-clip (2K1C) hypertensive rats. Male Wistar rats underwent 2K1C or sham operation (SO) and were housed for 4 weeks. Each group of rats, then, was further divided into 2 subgroups receiving oral administration of either 50 mg/kg BW GD extract or corn oil (vehicle) daily for 4 weeks. Noninvasive blood pressure (BP) and body weight were measured weekly throughout the study. Subsequently, the invasive measurement of arterial BP and the heart rate were determined in all anesthetized rats. The baroreceptor reflex sensitivity (BRS) was investigated by injection of either phenylephrine or sodium nitroprusside for bradycardia or tachycardia response, respectively. Histological examination of the heart and thoracic aorta was also performed in order to investigate the general morphology and the tumor necrosis factor alpha (TNF-α) expression. We found that the GD flower extract significantly diminished the BP and restored the impaired BRS. Moreover, it also decreased the TNF-α expression in the cardiac muscle and thoracic aorta of 2K1C when compared to the SO group. Taken together, our data showed that GD flower extract exhibits the cardiovascular protective effect in the 2K1C hypertensive rats.

Comparison between invasive and oscillometric blood pressure measurements in a controlled hemorrhage model in dorsally-recumbent isoflurane-anesthetized horses

Comparison between invasive and oscillometric blood pressure measurements in a controlled hemorrhage model in dorsally-recumbent isoflurane-anesthetized horses

A comparison of invasive arterial blood pressure measurement with oscillometric non-invasive blood pressure measurement in patients with sepsis.

This study aimed to compare non-invasive oscillometric blood pressure (NIBP) measurement with invasive arterial blood pressure (IBP) measurement in patients with sepsis. We conducted a retrospective study to evaluate the agreement between IBP and NIBP using the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Paired blood pressure measurements of mean arterial pressure (MAP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were compared using Bland-Altman analysis and paired Student's t test. We also focus on the effect of norepinephrine (NE) on the agreement between the two methods and the association between blood pressure and mortality during intensive care unit (ICU) stay. A total of 96,673 paired blood pressure measurements from 6060 unique patients were analyzed in the study. In Bland-Altman analysis, the bias (± SD, 95% limits of agreement) was 6.21mmHg (± 12.05mmHg, -17.41 to 29.83mmHg) for MAP, 0.39mmHg (± 19.25mmHg, -37.34 to 38.12mmHg) for SBP, and 0.80mmHg (± 12.92mmHg, -24.52 to 26.12mmHg) for DBP between the two techniques. Similarly, large limits of agreement were shown in different groups of NE doses. NE doses significantly affected the agreement between IBP and NIBP. SBP between the two methods gave an inconsistent assessment of patients' risk of ICU mortality. IBP and NIBP were not interchangeable in septic patients. Clinicians should be aware that non-invasive MAP was clinically and significantly underestimated invasive MAP.

Blood Pressure Estimation Based on PPG and ECG Signals Using Knowledge Distillation.

Easy access bio-signals are useful for alleviating the shortcomings and difficulties associated with cuff-based and invasive blood pressure (BP) measurement techniques. This study proposes a deep learning model, trained using knowledge distillation, based on photoplethysmographic (PPG) and electrocardiogram (ECG) signals to estimate systolic and diastolic blood pressures. The estimation model comprises convolutional layers followed by one bidirectional recurrent layer and attention layers. The training approach involves knowledge distillation, where a smaller model (student model) is trained by leveraging information from a larger model (teacher model). The proposed multistage model was evaluated on 1205 subjects from Medical Information Mart for Intensive Care (MIMIC) III database using the Association for the Advancement of Medical Instrumentation (AAMI) and the standards of the British Hypertension Society (BHS). The results revealed that our model performance achieved grade A in estimating both systolic blood pressure (SBP) and diastolic blood pressure (DBP) and met the requirements of the AAMI standard. After training with knowledge distillation (KD), the model achieved a mean absolute error and standard deviation of 2.94 ± 5.61mmHg for SBP and 2.02 ± 3.60mmHg for DBP. Our results demonstrate the benefits of the knowledge distillation training method in reducing the number of parameters and improving the predictive accuracy of the blood pressure regression model.

Effectiveness of the preventive administration of vasoactive amines in counterbalancing significant patient blood pressure drops following nimodipine administration during mechanical thrombectomy procedures

Background Focal vasospasm (FV) of the occluded vessel can occur during the endovascular treatment of acute ischemic stroke (AIS). Nimodipine is commonly used to treat vasospasm and can play a role in distinguishing it from artery narrowing due to iatrogenic dissection or residual clot. However, nimodipine administration can result in arterial hypotension and subsequent enlargement of the ischemic core. Objective To assess the efficacy of preventive and continuous vasoactive amine infusion to counterbalance nimodipine-induced hypotension. Methods We reviewed data from a prospective registry of patients treated for AIS between January 2019 and January 2022 who were administered nimodipine. All patients were equipped with an arterial cannula for invasive blood pressure measurement and given vasoactive amines preemptively before general anesthesia and throughout the procedure. Data obtained from invasive monitoring of mean arterial blood pressure (MABP) in a time-lapse of 25 min before and after nimodipine administration were analyzed. Results MABP significantly decreased after nimodipine administration but remained within the recommended range (81.79 ± 0.49 mmHg). Nimodipine was effective in reducing FV caused by stent retriever passage in 76.3% of cases. Furthermore, it proved valuable in diagnosing iatrogenic dissection (9.2%), residual clot (10.5%), or intracranial stenosis (4%). Conclusions Infusion of vasoactive amines effectively counteracted the intraarterial nimodipine effect, thus avoiding frank arterial hypotension during endovascular treatment. Nimodipine has been useful in differentiating the diagnosis of FV resulting from mechanical thrombectomy and other potential causes, such as iatrogenic dissection or residual clot.

History of blood pressure measurement in newborns and infants.

The development of methods for measuring blood pressure (BP) in newborns and small children has a rich history. Methods for BP measuring in adults had to be adapted to this age group. For measuring BP in direct invasive way, a suitable approach had to be found to access the arterial circulation through the umbilical and later radialis artery. Currently, results obtained from direct invasive BP measurement are considered the "gold standard". The development of non-invasive methods for BP measuring in newborns and children began with the use of von Basch's sphygmomanometer (1880). In 1899, Gustav Gärtner constructed the device, which was the basis for the flush method. After the discovery of the palpation and auscultation methods, these methods were also used for BP measurement in newborns and children, however, the BP values obtained in these ways were typically underestimated using excessively wide cuffs. From the auscultation method, methods utilizing ultrasound and infrasound to detect arterial wall movement and blood flow were later developed. The oscillometric method for BP measurement was introduced by E. J. Marey so early as in 1876. In 1912, P. Balard used the oscillometric technique to measure blood pressure in a large group of newborns. Through different types of oscillometers using various methods for detecting vascular oscillations (such as xylol method, impedance and volume plethysmography, etc.), the development has continued to assessment of vascular oscillations by modern sensor technology and software. For continuous non-invasive blood pressure measurement, the volume-clamp method, first described by Jan Peňáz in 1968, was developed. After modification for use in newborns, application of the cuff to the wrist instead of the finger, it is primarily used in clinical physiological studies to evaluate beat-to-beat BP and heart rate pressure variability, such as in the determination of the baroreflex sensitivity.

Prehospital hemodynamic instability: invasive blood pressure measurement—the future?

Prehospital hemodynamic instability: invasive blood pressure measurement—the future?

Abstract 18759: Reliability and Accuracy of Non-Invasive versus Invasive Blood Pressure Monitoring During Atrial Fibrillation Ablation

Introduction Patients with atrial fibrillation (AF) have multiple confounders that could affect the reliability of non-invasive blood pressure (NIBP). We sought to investigate if AF and paced rhythms (PR) modify the reliability of NIBP and accuracy against an invasive blood pressure (IBP) reference, as compared to sinus rhythm (SR), and impact NIBP validity for procedural monitoring. Hypothesis Changes in heart rhythm between AF, SR and PR, within a patient would not alter the reliability and accuracy of NIBP. Methods We conducted an observational study in patients undergoing an AF ablation procedure under general anesthesia with paired IBP, NIBP, and heart rhythm measurements available. Results We evaluated 91 patients ( Table 1 ) with 1,179 usable NIBP vs. IBP pairs; 547 (46.4%) during SR, 376 during AF (31.9%), and 256 (21.7%) during PR. In the entire sample, the average difference (standard error) between systolic NIBP and IBP was 2.9 (1.8) mmHg (P=0.10 against H0=0) with a within-subject standard deviation (SD) for the difference of 11.6 mmHg and intraclass correlation coefficient of 0.76 ( Fig. 1 ). Systolic NIBP was higher on average vs. IBP when in SR (6.2 [1.1] mmHg; P&lt;0.001), but not when in AF (1.5 [2.6] mmHg; P=0.55) or in PR (-2.0 [3.3] mmHg; P=0.54). However, the within-patient SD of the difference was high in SR, AF, and PR (SD 10.5, 12.9, and 11.9 mmHg, respectively). Results were similar for diastolic and mean NIBP vs. IBP. Conclusion AF or PR, as compared to SR, did not materially change the reliability and accuracy of NIBP vs. IBP. However, the high within-patient variation in systolic NIBP versus IBP raises concerns on the validity of NIBP for systolic blood pressure monitoring.

Hemodynamics and cutaneous microcirculation during induction of general anesthesia with and without esketamine.

Currently, there are limited data on the effect of macrocirculatory hemodynamic changes on human microcirculation, especially during the induction of general anesthesia (GA). We performed a non-randomized observational trial on patients receiving GA for elective surgery. In the control group (CG), for GA induction sufentanil, propofol, and rocuronium was administered. Patients assigned to the esketamine group (EG) received additional esketamine for GA induction. Invasive blood pressure (IBP) and pulse contour cardiac output (CO) measurement were performed continuously. Microcirculation was assessed using cutaneous Laser Doppler Flowmetry (forehead and sternum LDF), peripheral and central Capillary Refill Time (pCRT, cCRT), as well as brachial temperature gradient (Tskin-diff) at baseline, 5, 10 and 15 minutes after induction of GA. 42 patients were included in the analysis (CG n = 22, EG n = 20). pCRT, cCRT, Tskin-diff, forehead and sternum LDF decreased following GA induction in both groups. IBP and CO were significantly more stable in esketamine group. However, the changes in the microcirculatory parameters were not significantly different between the groups. The addition of esketamine for GA induction warranted better hemodynamic stability for the first five minutes, but had no significant effect on any of the cutaneous microcirculatory parameters measured.

Discrepancy between two invasive blood pressure measurements in patients receiving intra-aortic balloon pump therapy

BackgroundHemodynamic monitoring is imperative for patients with cardiogenic shock undergoing Intra-aortic Balloon Pump (IABP) therapy. Blood pressure monitoring encompasses non-invasive, invasive peripheral arterial pressure (IPAP), and invasive central aortic pressure (ICAP) methods. However, marked disparities exist between IPAP and ICAP. This study examined the discrepancies between IPAP and ICAP and their clinical significance.MethodsA retrospective analysis was conducted on cardiogenic shock patients who underwent IABP therapy and were admitted to the Coronary Care Unit (CCU) of a tertiary hospital in China from March 2017 to November 2022. The Bland–Altman plot illustrated the discrepancy between IPAP and ICAP. A clinically significant difference between ICAP and IPAP measurements was defined as ≥ 10 mmHg, which could necessitate alterations in blood pressure management according to current guidelines that recommend maintaining a mean arterial pressure (MAP) ≥ 70 mmHg.ResultsIn total, 162 patients were included in the final analysis. In patients without vasopressors, the difference between ICAP and IPAP was 5.73 mmHg (95% limits of agreement [LOA], -16.98 to 28.44), whereas, in patients with vasopressors, it was 4.36 mmHg (95% LOA, -17.31 to 26.03). ICAP measurements exceeded IPAP in patients undergoing IABP therapy. However, the difference was not statistically significant between the two groups. Multivariate logistic regression revealed that higher serum lactate levels (Odds ratio [OR], 1.14; 95% confidence interval [CI], 1.03–1.27; p = 0.013) and age ≥ 60 years (OR, 13.20; 95% CI, 1.50–115.51; p = 0.020) were associated with an increased likelihood of a clinically significant MAP discrepancy. Conversely, a history of coronary heart disease was associated with a decreased likelihood (OR, 0.34; 95% CI, 0.13–0.90; p = 0.031).ConclusionsNotable discrepancies between ICAP and IPAP measurements exist in cardiogenic shock patients undergoing IABP therapy. ICAP exceeds IPAP, and factors such as age ≥ 60 years, elevated lactic acid levels, and absence of coronary heart disease contribute to this discrepancy. Enhanced vigilance is warranted for these patients, and the consideration of peripheral invasive monitoring in conjunction with IABP therapy is advised.

Ketone body 3-hydroxybutyrate elevates cardiac output through peripheral vasorelaxation and enhanced cardiac contractility

The ketone body 3-hydroxybutyrate (3-OHB) increases cardiac output and myocardial perfusion without affecting blood pressure in humans, but the cardiovascular sites of action remain obscure. Here, we test the hypothesis in rats that 3-OHB acts directly on the heart to increase cardiac contractility and directly on blood vessels to lower systemic vascular resistance. We investigate effects of 3-OHB on (a) in vivo hemodynamics using echocardiography and invasive blood pressure measurements, (b) isolated perfused hearts in Langendorff systems, and (c) isolated arteries and veins in isometric myographs. We compare Na-3-OHB to equimolar NaCl added to physiological buffers or injection solutions. At plasma concentrations of 2–4 mM in vivo, 3-OHB increases cardiac output (by 28.3±7.8%), stroke volume (by 22.4±6.0%), left ventricular ejection fraction (by 13.3±4.6%), and arterial dP/dtmax (by 31.9±11.2%) and lowers systemic vascular resistance (by 30.6±11.2%) without substantially affecting heart rate or blood pressure. Applied to isolated perfused hearts at 3–10 mM, 3-OHB increases left ventricular developed pressure by up to 26.3±7.4 mmHg and coronary perfusion by up to 20.2±9.5%. Beginning at 1–3 mM, 3-OHB relaxes isolated coronary (EC50=12.4 mM), cerebral, femoral, mesenteric, and renal arteries as well as brachial, femoral, and mesenteric veins by up to 60% of pre-contraction within the pathophysiological concentration range. Of the two enantiomers that constitute racemic 3-OHB, D-3-OHB dominates endogenously; but tested separately, the enantiomers induce similar vasorelaxation. We conclude that increased cardiac contractility and generalized systemic vasorelaxation can explain the elevated cardiac output during 3-OHB administration. These actions strengthen the therapeutic rationale for 3-OHB in heart failure management.

Evaluation of the agreement between lingual and thoracic limb noninvasive blood pressure with invasive blood pressure measurements in anaesthetized horses

ObjectiveTo evaluate the agreement between noninvasive arterial blood pressure (NIBP) measured from the tongue and thoracic limb with invasive blood pressure (IBP), and to compare NIBP measured from the tongue and thoracic limb in anaesthetized horses. Study designProspective clinical study. AnimalsA group of eight client-owned healthy horses anaesthetized for scheduled procedures, American Society of Anesthesiologists classification I–II, weighing (mean ± standard deviation) 498 ± 91 kg and aged 7.8 ± 6.75 years. MethodsAnimals were premedicated with intravenous (IV) romifidine (0.04–0.08 mg kg–1) and methadone (0.1 mg kg–1). General anaesthesia was induced IV with ketamine (2.5 mg kg–1) and midazolam (0.05 mg kg–1) and maintained with isoflurane. The facial artery was catheterized for IBP measurements. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were recorded from the NIBPtongue, NIBPlimb and IBP every 20 minutes during the procedure. Agreement between NIBP and IBP was evaluated based on the American College of Veterinary Internal Medicine criteria and American Association for Medical Instrumentation criteria using the Bland–Altman method. ResultsThe mean bias and precision between IBP and NIBP measured from the tongue met the standards for all pressure ranges (< 10 mmHg and < 15 mmHg, respectively). NIBP measurements from the tongue and thoracic limb tended to underestimate IBP measurements. During hypotension, MAPtongue and DAPtongue overestimated IBP, but both precision and accuracy met the criteria. The overall accuracy and precision of NIBPlimb was poorer than NIBPtongue. The percentage of NIBPtongue that differed from IBP by < 10 mmHg was higher than that recorded with NIBPlimb for SAP (46% versus 25%), MAP (77% versus 28%) and DAP (79% versus 19%). Conclusions and clinical relevanceThe tongue is a clinically suitable alternative for assessing arterial blood pressure compared with the thoracic limb and can reliably detect hypotension in healthy anaesthetized horses.

Organisation, staffing and resources of critical care units in Kenya.

To describe the organisation, staffing patterns and resources available in critical care units in Kenya. The secondary objective was to explore variations between units in the public and private sectors. An online cross-sectional survey was used to collect data on organisational characteristics (model of care, type of unit, quality- related activities, use of electronic medical records and participation in the national ICU registry), staffing and available resources for monitoring, ventilation and general critical care. The survey included 60 of 75 identified units (80% response rate), with 43% (n = 23) located in government facilities. A total of 598 critical care beds were reported with a median of 6 beds (interquartile range [IQR] 5-11) per unit, with 26% beds (n = 157) being non functional. The proportion of ICU beds to total hospital beds was 3.8% (IQR 1.9-10.4). Most of the units (80%, n = 48) were mixed/general units with an open model of care (60%, n = 36). Consultants-in-charge were mainly anesthesiologists (69%, n = 37). The nurse-to-bed ratio was predominantly 1:2 with half of the nurses formally trained in critical care. Most units (83%, n = 47) had a dedicated ventilator for each bed, however 63% (n = 39) lacked high flow nasal therapy. While basic multiparametric monitoring was ubiquitous, invasive blood pressure measurement capacity was low (3% of beds, IQR 0-81%), and capnography moderate (31% of beds, IQR 0-77%). Blood gas analysers were widely available (93%, n = 56), with 80% reported as functional. Differences between the public and private sector were narrow. This study shows an established critical care network in Kenya, in terms of staffing density, availability of basic monitoring and ventilation resources. The public and private sector are equally represented albeit with modest differences. Potential areas for improvement include training, use of invasive blood pressure and functionality of blood gas analysers.

Evaluation of agreement between invasive and non-invasive blood pressure measurement using the PetMAP™ device in rabbits.

Measurement of arterial blood pressure is recommended in anaesthetized animals to guide perioperative treatment. Invasive blood pressure measurement is considered the gold standard, however it is also technically challenging, requires specialised equipment and carries certain risks. For these reasons, non-invasive blood pressure measurement devices are commonly used and are expected to provide accurate and reliable results. This requirement is particularly true for rabbits, in whom peri-anaesthetic hypotension is commonly observed and in whom perioperative mortality remains disproportionally high. Several authors have compared different non-invasive devices with invasive measurements in rabbits and have reported contrasting results. However, to date no comparison between invasive measurements and the PetMAP™ device, that has been designed specifically for veterinary medicine, has been reported. The aim of the study was the comparison of invasive blood pressure measurement with PetMAP™ in rabbits. We hypothesised that PetMAP™ would show acceptable agreement with the invasive measurements according to the American College of Veterinary Internal Medicine guidelines. Sixteen client-owned rabbits presenting for various surgical interventions were included in the study. Invasive measurements were performed by cannulation of an auricular artery. The PetMAP™ cuff was applied distal to the elbow according to the manufacturer's guidelines. For each measurement with PetMAP™, three invasive blood pressure values were recorded. The mean of the three invasive values was compared with one value measured with PetMAP™. Data collected from 16 rabbits were used for statistical analysis. In the clinical setting, the PetMAP™ device showed significant overestimation of systolic, diastolic and mean arterial pressure, which were measured in the auricular artery. In addition, the bias was not constant, implying that the device poorly predicted changes in blood pressure. The PetMAP™ device did not meet any of the American College of Veterinary Internal Medicine recommendations.