Arterial Blood Pressure Measurements Research Articles

On the Regulation of Arterial Blood Pressure by an Intracranial Baroreceptor

Introduction: There is significant evidence for the existence of an intracranial baroreceptor mechanism(s) capable of sensing physiological changes in cerebral blood flow (Marina et al., 2020). However, little is known about the sensitivity of this mechanism to changes in brain perfusion and its interaction with inputs from the peripheral (arterial) baroreceptors. The aim of this study was to characterise the cardiovascular responses to physiological changes in cerebral perfusion induced by experimental manipulations of intracranial pressure (ICP). Methods: The experiments were performed in adult Sprague-Dawley rats (250–300 g), anesthetized with urethane (induction: 1.3 g kg−1, i.p.; maintenance: 10–25 mg kg−1 h−1, i.v.). The femoral artery and vein were cannulated for measurement of arterial blood pressure (ABP) and administration of anaesthetic. The trachea was cannulated, and the animal was mechanically ventilated. The lateral cerebral ventricles were cannulated and connected via saline-filled catheters to a pressure transducer to record ICP and to a “water column” to allow controlled manipulation of ICP. The experiments included the denervation of the arterial baroceptors, stimulation of the aortic depressor nerve and recording of renal sympathetic nerve activity. Results: The resting ICP in rats anesthetized with urethane was 6.2 ± 0.7 mmHg (n=8). Following a small craniotomy that reduced ICP to 0 mmHg, ABP decreased by 11.2 mmHg (n=6) within 30 min. Restoring the integrity of the intracranial space increased ABP to the baseline level. Progressive increases in ABP were observed in response to experimentally-induced increases in ICP by 5, 10, 15 and 20 mmHg, revealing a linear relationship between ICP and systemic arterial pressure within the physiological range of ICP changes. In the absence of inputs from the arterial baroceptors (bilateral sino-aortic denervation and vagotomy) the ABP responses to ICP increases were preserved. Analysis of the ABP and heart rate responses to the electrical stimulation of the aortic depressor nerve suggested baroreflex re-setting at raised ICP. Renal nerve recordings demonstrated increased sympathetic activity at raised ICP (172 ± 34.91 % at 20 mmHg ICP (p=0.003; n=7) with markedly enhanced bursts of activity during the inspiratory phase of the respiratory cycle. Conclusion: These data demonstrate that the intracranial baroceptor mechanism is highly sensitive to changes in cerebral perfusion within the physiological range and suggest that cerebral blood flow is an important determinant of systemic ABP. The data suggest that at raised ICP the baroreflex control of sympathetic vasomotor activity is reset and provides effective control of arterial blood pressure at a higher level required to compensate for reduced brain perfusion. Marina, N., Christie, I.N., Korsak, A., Doronin, M., Brazhe, A., Hosford, P.S., Wells, J.A., Sheikhbahaei, S., Humoud, I., Paton, J.F. and Lythgoe, M.F., 2020. Astrocytes monitor cerebral perfusion and control systemic circulation to maintain brain blood flow. Nature Communications, 11(1), 131. This PhD Studentship is funded by the British Heart Foundation. This is the full abstract presented at the American Physiology Summit 2024 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 limb and cuff positioning on measurement of arterial blood pressure with an oscillometry device (PetMAP) in anaesthetized cats

Arterial blood pressure (ABP) is often measured with oscillometry during anaesthesia. Changing the height of the measuring cuff with respect to the level of the heart is known to affect oscillometry accuracy in some species, however; this effect has not been investigated in cats. The objective of this study was to determine the effects of raising and lowering the measuring cuff from standard position (level of the heart) on ABP, measured with PetMAP, in anaesthetised cats. ABP readings were obtained from 29 cats with the cuff at standard position (baseline), and 5cm above and below the heart. The end-tidal isoflurane concentrations were maintained constant during data acquisition.There were no differences between baseline values and those measured below the heart, while ABP measured above the heart was consistently lower than baseline for both the thoracic and pelvic limbs (P < 0.001), with absolute differences of 8.2 (2.5 – 14) mmHg and 6.5 (3.0 – 15.0) mmHg, respectively. Systolic ABP readings at the pelvic limb were consistently higher than those at the thoracic limb at standard position (112 ± 26 versus 103 ± 21mmHg, p = 0.010), above (106 ± 22 versus 95 ± 20mmHg, p = 0.003), and below the heart (116 ± 26 versus 107 ± 22mmHg, p = 0.011). This study shows that raising the cuff by 5cm above the heart, which may become necessary during procedural positioning, results in clinically significant underestimation of ABP measured with PetMAP.

EXPLORING THE EFFECTS OF VIGOROUS INTERVAL TRAINING, MODERATE RESISTANCE TRAINING AND PILATES ON ARTERIAL STIFFNESS AND BLOOD PRESSURE DURING PREGNANCY: A RANDOMISED CROSS-OVER TRIAL

INTRODUCTION Regular moderate intensity exercise throughout pregnancy provides significant benefits to both maternal and foetal cardiovascular health outcomes. Current exercise guidelines recommend a combination of moderate intensity aerobic and resistance training (RT). However, there is limited research exploring the cardiovascular effects of higher intensities (vigorous/high) in comparison to common pregnancy exercise modalities such as RT and Pilates (PIL). AIM: To investigate the acute effects of three modes of exercise (resistance, vigorous aerobic intervals and Pilates) during trimester two (T2) and three (T3) of pregnancy on measures of arterial stiffness (pulse wave velocity [PWV]) and blood pressure (BP). METHODS Eleven women with uncomplicated pregnancies (age 32 ± 3 years, pre-pregnancy BMI 23.9 ± 3.5 kg/m2) completed testing in T2 (average 20 ± 1.6 weeks gestation) and T3 (average 29 ± 2.5 weeks gestation). Participants performed one each of vigorous intensity interval training (VIIT) (∼33 min), resistance training (RT) (∼35 min) and Pilates (PIL) (∼35 min) in T2 and T3 in randomised order approximately 1 week apart each trimester. Resting outcome measures of PWV, BP and foetal heart rate (FHR) were obtained following 5 minutes of rest and again immediately and 10 minutes post exercise session. BP, maternal heart rate (MHR), and rating of perceived exertion (RPE) were monitored throughout. RESULTS There was no difference in the acute PWV response to each type of exercise across the trimesters (1 min VIIT: T2 = 5.53 ± 0.85m/s, T3 = 5.26 ± 0.67m/s, 95%CI[-1.36-0.67]; RT: T2 = 5.4 ± 0.80m/s, T3 = 5.48 ± 0.56m/s, 95%CI[-0.88-1.10]; PIL: T2 = 5.44 ± 0.68m/s, T3 = 5.44 ± 0.68m/s, 95%CI[-0.93-1.01]). There was no significant difference in the acute response in SBP to VIIT (T2 = 116 ± 12.1mmHg, T3 = 122 ± 7.2mmHg, 95%CI[-0.42 - 1.65]. SBP was significantly higher in T3 than T2 1 minute following PIL (T2 = 110 ± 5.8mmHg, T3 = 121 ± 11.7mmHg, 95%CI[0.04-2.1]) and 10 minutes following RT (T2 = 105 ± 10.1mmHg, T3 = 116 ± 5.0mmHg, 95%CI[0.27 - 2.46]. CONCLUSION VIIT, RT and PIL appear to elicit similar post-exercise haemodynamic and arterial stiffness responses in both the mother and foetus. As such, VIIT may be a suitable addition to standard moderate intensity and RT prescription during an uncomplicated pregnancy.

An Acute Bout of Subconcussive Head Impacts Does Not Change Intracranial Pressure

Purpose: Subconcussive head impacts (SHI) are known to cause a variety of negative sequelae including increased plasma concentrations of neuronal structural and glial proteins, attenuated neurovascular coupling, and impaired vestibular function. Traumatic brain injuries are associated with an increase in intracranial pressure (ICP). However, it is unknown whether an acute bout of SHI increases ICP. We tested the hypothesis that estimates of ICP via ultrasound assessments of optic nerve sheath diameter (ONSD) would be greater following a single session of repetitive SHI versus a control condition. Methods: 14 healthy participants (age: 19±2 y; BMI: 21±4 kg/m2, 3 women) with at least 3 y of soccer heading experience completed two experimental conditions in a randomized crossover design. 20 soccer headings were used to induce repetitive SHI and 20 soccer kicks were used as the control condition. A soccer ball was projected from a soccer JUGS machine (40 km/h, 12.2 m away) every 30 s for both conditions. ONSD assessed via ultrasound is associated with direct measures of ICP. Subjects were in the supine position during ONSD (transverse plane, each eye; B-mode linear array ultrasound), heart rate (HR; 3-lead ECG), and mean arterial blood pressure (MAP; photoplethysmography) measurements conducted at baseline prior to heading/kicking and at 2 h, 24 h, and 72 h post. ONSDs were measured 3 mm under the bulb in triplicate for each eye and the mean values were used for analyses. Inter-eye ONSD values were also averaged for analyses. Clinical intervention to alleviate elevated ICP is indicated when ONSD is &gt; 5.0 mm. Data were analyzed using a mixed-effects model with repeated measures with time and condition as within subject factors. Data are presented as mean ± SD if statistically significant. Results: No subjects had an ONSD &gt; 5.0 mm in either eye following heading or kicking. Left ONSD was greater than baseline at 2 h post heading (2.89 ± 0.25 mm vs. 2.99 ± 0.27 mm; p = 0.0157) and greater than baseline at 2 h (2.92 ± 0.37 mm vs. 2.98 ± 0.31 mm; p = 0.0352) and 72 h (3.08 ± 0.26 mm; p = 0.0067) post kicking. Left ONSD at 72 h post kicking was greater than heading (3.08 ± 0.26 mm vs. 2.93 ± 0.25 mm; p = 0.0022). There were no interaction effects for right ONSD (p = 0.4686), average ONSD (p = 0.1178), HR (p = 0.1039) or MAP (p = 0.3889). Conclusion: Neither the heading nor kicking intervention elicited a clinically relevant ONSD that would require medical attention. Contrary to our hypothesis, an acute bout of 20 soccer headers did not evoke greater ONSD in healthy subjects versus kicking. Therefore, our data indicate that a single session of SHI does not increase ICP. This is the full abstract presented at the American Physiology Summit 2024 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.

Hypertension Severity and Declines in Left Ventricular Ejection Fraction Among Women Receiving Adjuvant Chemotherapy for Breast Cancer (WF-97415 UPBEAT).

Hypertension is a risk factor for experiencing left ventricular ejection fraction (LVEF) declines during receipt of potentially cardiotoxic breast cancer (BC) treatment. We sought to determine whether the hypertension stage is associated with LVEF decline during BC treatment. Across 24 centers, cardiac magnetic resonance measures of LVEF and brachial arterial blood pressure (BP) measurements were performed in women with stages I to III BC before and 3 months after initiating potentially cardiotoxic chemotherapy. Using multivariable analysis, we assessed in a blinded fashion the association between 3-month ΔLVEF and precancer treatment American Heart Association/American College of Cardiology stages of hypertension. Among 204 women, age averaged 56±1 years with 75% being White and 20% of Black race. Participants received anthracycline (45.6%), trastuzumab (22.5%), cyclophosphamide (52.9%), or paclitaxel (50%). After accounting for pretreatment LVEF, diabetes status, tobacco use, age, the number of antihypertensive medications, and body mass index, those with stage II hypertension experienced an LVEF decline of -2.89% ([95% CI, -0.69% to -5.19%]; P=0.01) relative to individuals with normal BP. Other stages saw nonsignificant declines relative to normal BP to elevated BP (-1.63% [95% CI, -0.62% to 3.88%]; P=0.16) and stage I hypertension (-0.94% [95% CI, -0.90% to 2.78%]; P=0.32). Compared with women receiving treatment for BC with normal BP, there is a stronger association of decline in LVEF in women with stage II hypertension relative to women with other hypertension stages. This raises the possibility that stage along with hypertension presence may be associated with an increased risk for the LVEF decline among women receiving potentially cardiotoxic chemotherapy for BC. URL: https://www.clinicaltrials.gov; Unique identifier: NCT02791581 and NCT01719562.

Constraint Latent Space Matters: An Anti-anomalous Waveform Transformation Solution from Photoplethysmography to Arterial Blood Pressure

Arterial blood pressure (ABP) holds substantial promise for proactive cardiovascular health management. Notwithstanding its potential, the invasive nature of ABP measurements confines their utility primarily to clinical environments, limiting their applicability for continuous monitoring beyond medical facilities. The conversion of photoplethysmography (PPG) signals into ABP equivalents has garnered significant attention due to its potential in revolutionizing cardiovascular disease management. Recent strides in PPG-to-ABP prediction encompass the integration of generative and discriminative models. Despite these advances, the efficacy of these models is curtailed by the latent space shift predicament, stemming from alterations in PPG data distribution across disparate hardware and individuals, potentially leading to distorted ABP waveforms. To tackle this problem, we present an innovative solution named the Latent Space Constraint Transformer (LSCT), leveraging a quantized codebook to yield robust latent spaces by employing multiple discretizing bases. To facilitate improved reconstruction, the Correlation-boosted Attention Module (CAM) is introduced to systematically query pertinent bases on a global scale. Furthermore, to enhance expressive capacity, we propose the Multi-Spectrum Enhancement Knowledge (MSEK), which fosters local information flow within the channels of latent code and provides additional embedding for reconstruction. Through comprehensive experimentation on both publicly available datasets and a private downstream task dataset, the proposed approach demonstrates noteworthy performance enhancements compared to existing methods. Extensive ablation studies further substantiate the effectiveness of each introduced module.

A New Approach to Vascular Screening: Identification of Impaired Vascular Function Using the FMSF Technique.

Arterial blood pressure monitoring plays an important role in preventive medicine, allowing, in selected cases, the identification of vascular dysfunction. In this review, we propose a new non-invasive approach to assessment of the circulatory system, based on its reaction to hypoxia induced by post-occlusive reactive hyperemia (PORH). Three key parameters can be used for vascular screening: the Reactive Hyperemia Response (RHR), which represents the overall reaction of the macro- and microcirculation to transient hypoxia; Hypoxia Sensitivity (HS), which reflects hypoxia-induced activation of myogenic oscillations of the microcirculation; and Normoxia Oscillatory Index (NOI), which characterizes microcirculatory oscillations under normoxia conditions. A method for assessing these parameters, analogous in simplicity to arterial blood pressure measurement, is provided by the Flow Mediated Skin Fluorescence (FMSF) technique. Reference values are proposed based on numerous test measurements.

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.

Evaluation of a novel cuffless photoplethysmography-based wristband for measuring blood pressure according to the regulatory standards.

Elevated blood pressure (BP) is a key risk factor in cardiovascular diseases. However, obtaining reliable and reproducible BP remains a challenge. This study, therefore, aimed to evaluate a novel cuffless wristband, based on photoplethysmography (PPG), for continuous BP monitoring. Predictions by a PPG-guided algorithm were compared to arterial BP measurements (in the sub-clavian artery), obtained during cardiac catheterization. Eligible patients were included and screened based on AAMI/European Society of Hypertension (ESH)/ISO Universal Standard requirements. The machine learning-based BP algorithm required three cuff-based initialization measurements in combination with ∼100 features (signal-derived and patient demographic-based). Ninety-seven patients and 420 samples were included. Mean age, weight, and height were 67.1 years (SD 11.1), 83.4 kg (SD 16.1), and 174 cm (SD 10), respectively. Systolic BP was ≤100 mmHg in 48 samples (11%) and ≥160 mmHg in 106 samples (25%). Diastolic BP was ≤70 mmHg in 222 samples (53%) and ≥85 mmHg in 99 samples (24%). The algorithm showed mean errors of ±3.7 mmHg (SD 4.4 mmHg) and ±2.5 mmHg (SD 3.7 mmHg) for systolic and diastolic BP, respectively. Similar results were observed across all genders and skin colours (Fitzpatrick I-VI). This study provides initial evidence for the accuracy of a PPG-based BP algorithm in combination with a cuffless wristband across a range of BP distributions. This research complies with the AAMI/ESH/ISO Universal Standard, however, further research is required to evaluate the algorithms performance in light of the remaining European Society of Hypertension recommendations. www.clinicaltrials.gov, NCT05566886.

Three ultrasound guided plane blocks for perioperative analgesia in patients undergoing radical cystectomy: a randomized clinical trial

Background &amp;objective: Transmuscular quadratus lumborum plane block (QLPB), paravertebral plane block (PVPB), and erector spinae plane block (ESPB) are three regional anesthesia techniques for management of perioperative pain for surgical procedures on the trunk, including thorax and abdomen. We compared the effectiveness of PVPB, QLPB type III (QL3), and ESPB for perioperative analgesia during radical cystectomy performed for bladder cancer.&#x0D; Methodology: This randomized double-blind trial was performed on 120 patients, aged above 18 years, undergoing radical cystectomy under general anesthesia. Individuals were randomly divided into 3 equal groups: ESPB, PVPB, and QLPB. Blocks were performed under ultrasound guidance preoperatively on each side with 30 ml of 0.25% bupivacaine. Time to perform block and time to the first dose of morphine postoperatively, were noted. Intra-operative hemodynamic data, including MAP and heart rate (HR) were noted every 10 min for an hour, and then at 30 min intervals. Postoperatively, MAP and HR were recorded at 0, 2, 6, 12 and 24 hours. The connection between qualitative factors was investigated using the chi-square test and Fisher's exact test. For the purpose of comparing the groups, one-way ANOVA and the Bonferroni correction were used. A two-tailed P value &lt; 0.05 was considered significant.&#x0D; Results: Time to perform block was substantially reduced in ESPB and QL3 groups compared to PVPB group. Time to the first dose of morphine was substantially delayed in the PVPB group than ESPB and QL3 groups. Total 24 h morphine consumption was substantially lower in the PVPB group than ESPB and QL3 groups. Postoperative visual analog scale measurements were substantially lower at 15 min, 30 min, and 12 h in the PVPB group than ESPB and QL3 groups and at 6 h in the ESPB and QL3 groups than in PVPB group. Postoperative mean arterial blood pressure and heart rate measurements were substantially reduced at 0 and 12 h in the PVPB group than in ESPB and QL3 groups and at 6 h in the ESPB and QL3 groups than in PVPB group.&#x0D; Conclusions: The ultrasound guided paravertebral plane block was superior to quadratus lumborum plane block type III and erector spinae plane block in providing more effective analgesia but with higher time to perform block.&#x0D; Abbreviations: ESPB- Erector Spinae Plane Block; PVPB- Paravertebral Plane Block; QLPB- Quadratus Lumborum Plane Block; QL3- Quadratus Lumborum Plane Block Type III&#x0D; Keywords: Paravertebral Plane Block; Quadratus Lumborum Plane Block; Erector Spinae Plane Block; Ultrasound; Radical Cystectomy&#x0D; Citation: Seif NE, El-Kholy MM, Ali AR, Zalat MM, Elshazly M. Three ultrasound guided plane blocks for perioperative analgesia in patients undergoing radical cystectomy: a randomized clinical trial. Anaesth. pain intensive care 2024;28(1):85-91; DOI: 10.35975/apic.v28i1.2381&#x0D; Received: September 28, 2023; Reviewed: October 31, 2023; Accepted: October 31, 2023

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.

Rethinking Fluid Responsiveness during Septic Shock: Ameliorate Accuracy of Noninvasive Cardiac Output Measurements through Evaluation of Arterial Biomechanical Properties.

Beat-to-beat estimates of cardiac output from the direct measure of peripheral arterial blood pressure rely on the assumption that changes in the waveform morphology are related to changes in blood flow and vasomotor tone. However, in septic shock patients, profound changes in vascular tone occur that are not uniform across the entire arterial bed. In such cases, cardiac output estimates might be inaccurate, leading to unreliable evaluation of fluid responsiveness. Pulse wave velocity is the gold-standard method for assessing different arterial biomechanical properties. Such methods might be able to guide, personalize and optimize the management of septic patients.

Femoral Nailing in a Porcine Model Causes Bone Marrow Emboli in the Lungs and Systemic Emboli in the Heart and Brain.

Shaft fractures of the femur are commonly treated with intramedullary nailing, which can release bone marrow emboli into the bloodstream. Emboli can travel to the lungs, impairing gas exchange and causing inflammation. Occasionally, emboli traverse from the pulmonary to the systemic circulation, hindering perfusion and resulting in injuries such as heart and brain infarctions, known as fat embolism syndrome. We studied the extent of systemic bone marrow embolization in a pig model. Twelve anesthetized pigs underwent bilateral intramedullary nailing of the femur, while 3 animals served as sham controls. Monitoring included transesophageal echocardiography (TEE), pulse oximetry, electrocardiography, arterial blood pressure measurement, and blood gas and troponin-I analysis. After surgery, animals were monitored for 240 minutes before euthanasia. Post mortem, the heart, lungs, and brain were biopsied. Bone marrow emboli were found in the heart and lungs of all 12 of the pigs that underwent intramedullary nailing and in the brains of 11 of them. No emboli were found in the sham group. The pigs subjected to intramedullary nailing exhibited significant hypoxia (PaO2/FiO2 ratio, 410 mm Hg [95% confidence interval (CI), 310 to 510) compared with the sham group (594 mm Hg [95% CI, 528 to 660]). The nailing group exhibited ST-segment alterations consistent with myocardial ischemia and a significant increase in the troponin-I level compared with the sham group (1,580 ng/L [95% CI, 0 to 3,456] versus 241 ng/L [95% CI, 0 to 625] at the 240-minute time point; p = 0.005). TEE detected emboli in the right ventricular outflow tract, but not systemically, in the nailing group. Bilateral intramedullary nailing caused bone marrow emboli in the lungs and systemic emboli in the heart and brain in this pig model. The observed clinical manifestations were consistent with coronary and pulmonary emboli. TEE detected pulmonary but not systemic embolization. Femoral intramedullary nailing in humans is likely to result in embolization as described in our pig model. Focused monitoring is necessary for detection of fat embolism syndrome. Absence of visual emboli in the left ventricle on TEE does not exclude the occurrence of systemic bone marrow emboli.

Intracranial Pressure, Autoregulation, and Cerebral Perfusion in Infants With Nonsyndromic Craniosynostosis at the Time of Surgical Correction

BACKGROUND AND OBJECTIVE: Although an increased intracranial pressure (ICP) is a known problem in children with syndromic craniosynostosis, it remains unclear whether elevated ICP and impaired cerebral perfusion exist in nonsyndromic synostosis and should be defined as targets of primary treatment. This study aimed to investigate ICP, cerebral autoregulation (CAR), and brain perfusion in infants with nonsyndromic craniosynostosis at first surgical intervention. METHODS: Forty-three infants were prospectively included. The patients underwent perioperative measurement of mean arterial blood pressure, ICP, and brain perfusion before and after cranial vault decompression. Physiological parameters with possible influences on ICP and autoregulation/brain perfusion were standardized for age. CAR was assessed by the pressure reactivity index (PRx), calculated using the mean arterial blood pressure and ICP. RESULTS: Biparietal decompression was performed in 29 infants with sagittal synostosis (mean age, 6.1 ± 1.3 months). Fronto-orbital advancement was performed in 10 and 4 infants with metopic and unilateral coronal synostosis, respectively (mean age, 11.6 ± 2.1 months). An elevated ICP (&gt;15 mm Hg) was found in 20 of 26 sagittal (mean, 21.7 ± 4.4 mm Hg), 2 of 8 metopic (mean, 17.1 ± 0.4 mm Hg), and 2 of 4 unilateral coronal synostosis cases (mean, 18.9 ± 2.5 mm Hg). Initial ICP was higher in sagittal synostosis than in metopic/coronal synostosis (P = .002). The postdecompression ICP was significantly reduced in sagittal synostosis cases (P &lt; .001). The relative cerebral blood flow and blood flow velocity significantly increased after decompression. Impaired CAR was found in infants with a mean ICP &gt;12 mm Hg (PRx, 0.26 ± 0.32), as compared with those with a mean ICP ≤ 12 mm Hg (PRx, −0.37 ± 0.07, P = .001). CONCLUSION: Contrary to common belief, an elevated ICP and significantly impaired CAR can exist early in single suture synostosis, particularly sagittal synostosis. Because an influence of raised ICP on long-term cognitive development is known in other diseases, we suggest that preventing increased ICP during the phase of maximal brain development may be a goal for decompressive surgery, at least for sagittal synostosis cases.

Role of adding dexmedetomidine, ketamine, and magnesium sulphate to caudal block as preemptive analgesia in hypospadias repair in pediatrics: A randomized double-blinded prospective trial

ABSTRACT Background The caudal block (CB) is a quick, and safe approach for pediatric analgesia. Numerous adjuvants were added to extend the analgesia duration. Our trial aims to evaluate the significance of CB by adding dexmedetomidine, ketamine, and MgSO₄ to bupivacaine to provide postoperative analgesia in children undergoing hypospadias repair. Methods This randomized double-blinded study was performed on 75 male children undergoing hypospadias repair under CB. Patients were randomized into three equal groups. All received 0.5 ml/kg bupivacaine 0.25% caudally plus 1 ml volume containing either dexmedetomidine 1 μg/kg in Group D, 0.5 mg/kg ketamine in Group K or 50 mg of MgSO₄ in Group M. Results Time of first rescue analgesia was significantly delayed in group D (8.2 ± 3.45 h) than in group K (5.8 ± 2.85 h) and group M (3.7 ± 1.51 h) (P value = 0.007 vs. <0.001) and in group K than in group M (P value = 0.027). Heart rate and mean arterial blood pressure measurements after block and 60 min intraoperative reduced significantly in group D than in K and Group M. At 6 h and 12 h, FLACC scores were considerably lower with Group D compared to Group K, and Group M, and ketamine group compared to Group M at 4 h. The total amount of pethidine consumed 24 hours postoperatively was significantly lower in Group D than in Group K and Group M. Conclusions Dexmedetomidine as an additive to the CB significantly prolonged time to first analgesia required and decreased total rescue opioid consumption compared to ketamine and MgSO₄.

ARTERIAL CATHETERIZATION IN GREAT APES.

Anesthesia is frequently required to provide appropriate medical care to captive great apes. Anesthetic safety can be optimized through placement of an arterial catheter, which allows direct measurement of arterial blood pressure and easy sampling of arterial blood for blood-gas analysis. Arterial catheterization in great apes can be achieved through palpation-guided or ultrasound-guided placement with or without a modified Seldinger technique. Potential sites for arterial catheterization include the anterior tibial artery, caudal tibial and posterior saphenous arteries, dorsal pedal artery, femoral artery, radial artery, and brachial artery. Arterial catheterization is recommended for lengthy great ape anesthetic procedures or those involving invasive procedures.

The Advantages of Combined Regional and General Anesthesia in Ophthalmic Surgery in Children

Background: Regional anesthesia is a common procedure in an adult patient undergoing ophthalmic surgery, but it cannot be done alone in the pediatric age group. General anesthesia is accompanied by complications intra- and post-operatively. Objectives: to determine whether or not using regional anesthesia in combination with general anesthesia in pediatric eye procedures improves patient outcomes. Methods: Forty children, with an age range of 6 - 12 years were included in the study that was conducted at Ghazi Al-Hariri Hospital / Department of Ophthalmology and Ibn Al-Haytham (Ophthalmology Hospital), both teaching hospitals, from December 2018 to October 2019. These children were allocated into one of two groups: GA (general anesthesia) and GA-R (general anesthesia-regional anesthesia). Heart rates, mean arterial blood pressure, oculo-cardiac reaction, and postoperative nausea and vomiting were measured. All required approvals were obtained from the scientific committee of the Iraqi Board for Medical Specializations. Statistical analysis was done using SPSS V26, with a P value of &lt;0.05 considered significant. Results: None of the patients developed oculo-cardiac reactions or needed additives to the anesthesia given during surgery in the GA-R compared to the GA group. Intra-operative measurements of heart rates and mean arterial blood pressure were lower in the GA group than in the GA-R group (p&lt;0.05). Compared to the GA group, the GA-R group had a lower incidence of postoperative nausea and vomiting (p&lt;0.05). More patients in the GA group needed analgesia than in the GA-R group. Conclusion: Using regional anesthesia as a peribulbar block with general anesthesia is a safe and successful procedure in pediatric ocular surgeries. Received:Feb. 2023 Accepted: Sept. 2023 Published: Oct. 2023

Pressure- vs. volume-controlled ventilation and their respective impact on dynamic parameters of fluid responsiveness: a cross-over animal study

Background and goal of studyPulse pressure variation (PPV) and stroke volume variation (SVV), which are based on the forces caused by controlled mechanical ventilation, are commonly used to predict fluid responsiveness. When PPV and SVV were introduced into clinical practice, volume-controlled ventilation (VCV) with tidal volumes (VT) ≥ 10 ml kg− 1 was most commonly used. Nowadays, lower VT and the use of pressure-controlled ventilation (PCV) has widely become the preferred type of ventilation. Due to their specific flow characteristics, VCV and PCV result in different airway pressures at comparable tidal volumes. We hypothesised that higher inspiratory pressures would result in higher PPVs and aimed to determine the impact of VCV and PCV on PPV and SVV.MethodsIn this self-controlled animal study, sixteen anaesthetised, paralysed, and mechanically ventilated (goal: VT 8 ml kg− 1) pigs were instrumented with catheters for continuous arterial blood pressure measurement and transpulmonary thermodilution. At four different intravascular fluid states (IVFS; baseline, hypovolaemia, resuscitation I and II), ventilatory and hemodynamic data including PPV and SVV were assessed during VCV and PCV. Statistical analysis was performed using U-test and RM ANOVA on ranks as well as descriptive LDA and GEE analysis.ResultsComplete data sets were available of eight pigs. VT and respiratory rates were similar in both forms. Heart rate, central venous, systolic, diastolic, and mean arterial pressures were not different between VCV and PCV at any IVFS. Peak inspiratory pressure was significantly higher in VCV, while plateau, airway and transpulmonary driving pressures were significantly higher in PCV. However, these higher pressures did not result in different PPVs nor SVVs at any IVFS.ConclusionVCV and PCV at similar tidal volumes and respiratory rates produced PPVs and SVVs without clinically meaningful differences in this experimental setting. Further research is needed to transfer these results to humans.

Impaired cerebrovascular reactivity correlates with reduced retinal vessel density in patients with carotid artery stenosis: Cross-sectional, single center study.

The cerebral and retinal circulation systems are developmentally, anatomically, and physiologically interconnected. Thus, we hypothesized that hypoperfusion due to atherosclerotic stenosis of the internal carotid artery (ICA) can result in disturbances of both cerebral and retinal microcirculations. We aimed to characterize parameters indicating cerebrovascular reactivity (CVR) and retinal microvascular density in patients with ICA stenosis, and assess if there is correlation between them. In this cross-sectional study the middle cerebral artery (MCA) blood flow velocity was measured by transcranial Doppler (TCD) and, simultaneously, continuous non-invasive arterial blood pressure measurement was performed on the radial artery by applanation tonometry. CVR was assessed based on the response to the common carotid artery compression (CCC) test. The transient hyperemic response ratio (THRR) and cerebral arterial resistance transient hyperemic response ratio (CAR-THRR) were calculated. Optical coherence tomography angiography (OCTA) was used to determine vessel density (VD) on the papilla whole image for all (VDP-WIall) and for small vessels (VDP-WIsmall). The same was done in the peripapillary region: all (VDPPall), and small (VDPPsmall) vessels. The VD of superficial (VDMspf) and deep (VDMdeep) macula was also determined. Significance was accepted when p<0.05. Twenty-four ICA stenotic patients were evaluated. Both CVR and retinal VD were characterized. There was a significant, negative correlation between CAR-THRR (median = -0.40) and VDPPsmall vessels (median = 52%), as well as between VDPPall vessels (median = 58%), and similar correlation between CAR-THRR and VDP-WIsmall (median = 49.5%) and between VDP-WIall (median = 55%). The significant correlation between impaired cerebrovascular reactivity and retinal vessel density in patients with ICA stenosis suggests a common mechanism of action. We propose that the combined use of these diagnostic tools (TCD and OCTA) helps to better identify patients with increased ischemic or other cerebrovascular risks.

Some perspectives of continuous arterial blood pressure measurements: from kymograph to tonoarteriographic imaging

The measurement and monitoring of continuous arterial blood pressure (BP) have undergone significant evolution over the past 170 years, transitioning from ancient invasive approaches, like kymograph, to modern non-invasive and unobtrusive technologies such as tonoarteriography (TAG). This progressive shift has revolutionized the way we track BP, providing safer, more accurate, and convenient methods for monitoring BP. This paper aims to provide some historical perspectives on the development of continuous BP technology, highlight key milestones that have shaped the field, discuss the state-of-the-art two-dimensional TAG imaging, and address challenges for future unobtrusive BP measurements. In addition to presenting a concise review of the progression of continuous BP measurement technologies, this article also emphasizes the importance of adopting more precise, convenient and affordable approaches for personalized BP monitoring at home and patient care optimizations at hospitals, thereby empowering healthcare professionals to enhance pervasive hypertension management anywhere.