Conical Cuff Research Articles

Challenges in blood pressure measurement in children with obesity: focus on the cuff.

Childhood obesity is a well-known risk factor for primary hypertension (HTN), especially during puberty. Validated automated oscillometric devices based on universal protocols using proper cuffs according to arm sizes must be selected for blood pressure (BP) measurement in clinical practice. Recent recommendations have addressed the importance of accurate BP measurement in patients with obesity. The American Heart Association (AHA) suggests using a cone-shaped cuff, while the European Society of Hypertension (ESH) emphasizes the significance of cuff characteristics based on arm size. The applicability of cone-shaped cuffs over cylindrical cuffs has been studied in adults with obesity. Most studies focused on the upper arm's shape and provided evidence that the use of cylindrical cuffs may overestimate BP in individuals with obesity, while the conical cuff was proposed as a proper alternative. However, current validation studies for BP measurement devices have not included the arm's size as a recruiting criterion, which may compromise the accuracy of devices in individuals with obesity. This review discusses the role of arm characteristics in cuff selection and the potential role of conical cuffs as an alternative to commonly used cylindrical ones in BP measurement in pediatric patients with obesity.

Efficacy of Endotracheal Tube Cuff Modification in Preventing Ventilator-associated Pneumonia.

The aim of this study was to evaluate the effect of modifying the cuff on preventing ventilator-associated pneumonia (VAP).PubMed, Embase and Cochrane Library were systematically searched from inception toApril 2022, for randomised controlled trials (RCTs) that compared the effect of a new type of cuff intubation with traditional cuff intubation on VAP incidence and intensive-care unit (ICU) mortality in mechanically ventilated patients. Nine RCTswith1937 patients were finally evaluated. Thepooled results for the incidence of VAP showed that the modified cuffsignificantly decreased the morbidity of VAP compared with the traditional cuff (relative ratio(RR) = 0.73, 95% confidence interval(CI) 0.56-0.95, p = 0.02). The subgroup analysis revealed that polyurethane(PU) cuff (RR = 0.82, 95% CI 0.46-1.48, p = 0.52), conical cuff (RR = 0.97, 95% CI 0.73-1.28, p = 0.82) and PU-conical cuff (RR = 1.36, 95% CI 0.85-2.18, p = 0.20) did not decrease the incidence of VAP. Moreover, the improved cuff combined with subglottic secretion drainage(SSD) could significantly reduce the VAP incidence (RR = 0.58, 95% CI 0.44-0.77, p = 0.0001). In terms of ICU mortality, there was no statistically significant difference (RR = 0.83, 95% CI 0.68-1.02, p = 0.08) between the two groups. The modified cuff issuperior to the traditional cuff in VAP prevention. In particular, the modified cuff combined with subglottic secretion drainage has more advantages. Key Words: Ventilator-associated pneumonia, Intubation, Endotracheal cuff, Intensive care unit, Meta-analysis.

The effect of the endotracheal tube cuff shape on post-operative sore throat in surgeries longer than 120 min in supine position.

This study aimed at comparing the effects of cylindrical- and conical-cuff endotracheal tubes (ETTs) inflated with saline on cuff pressures, post-operative sore throat, and post-operative analgesic consumption in surgeries taking longer than 120 min. This study aimed at comparing the effects of cylindrical- and conical-cuff endotracheal tubes (ETTs) inflated with saline on cuff pressures, post-operative sore throat, and post-operative analgesic consumption in surgeries taking longer than 120 min. The study was performed on a total of 100 patients, aged 18-65 years, in the ASA I-III risk group, with cylindrical cuff (Group C, n = 50) and conical cuff (Group T, n = 50) ETT patients. Cuff pressure values of all patients were recorded. The cuff pressure values at all measurement times and maximum cuff pressure value were significantly lower in Group T than in Group C (p < 0.05). In the post-operative 24-h period, sore throat and total analgesic consumption were significantly lower in Group T than in Group C (p < 0.05). conical cuff ETTs prevent the increase in intraoperative cuff pressures, reduce the incidence of post-operative sore throat, and accordingly reduce post-operative analgesic consumption compared to cylindrical cuff ETTs.

A Conical Cuff and Other Stuff: Blood Pressure Monitoring in the Obese is Tough.

A Conical Cuff and Other Stuff: Blood Pressure Monitoring in the Obese is Tough.

RECTANGULAR CUFFS OVERESTIMATE BLOOD PRESSURE IN OBESE PEOPLE WITH VERY LARGE ARMS

Objective: Rectangular cuffs and bladders are currently used for blood pressure (BP) measurement at the upper arm. However, large arms always have a tronco-conical shape. Aim of this study was to ascertain whether rectangular and tronco-conical cuffs provide different readings in obese subjects with very large arms. Design and method: In 33 subjects with morbid obesity (BMI, 45 ± 5.0 Kg/m2.16 men) aged 51 ± 12 years, with arm mid-circumference ranging from 42 to 55 cm, and 33 subjects of control with standard arm circumference (range, 22–31 cm) the upper-arm frustum slant angle was measured. Two different rectangular and two different tronco-conical bladders of appropriate size and shape were constructed, on the basis of previous anthropometric measures obtained in our laboratory. In each subject, BP was measured in triplicate by two observers using the two cuffs in a random order. In addition, in the obese participants, the pressure under the two cuffs was measured at five pressure levels (60, 90, 120, 150 and 180 mmHg) using a paper-thin pressure sensor attached to the central point of the cuffs. Results: In all obese participants the upper arm shape was tronco-conical with slant angles ranging from 80.4 to 87.6° (mean 84.1 ± 1.4°). Systolic BP (SBP) and diastolic BP (DBP) differences between the troncoconical and the rectangular cuff were −4.8 ± 4.0 and −3.0 ± 4.3 mmHg, respectively, whereas they were negligible in the controls (SBP, p < 0.001 and DBP, p = 0.01). In the subjects of the top SBP quintile (SBP > = 150 mmHg), the between-cuff SBP difference was −9.1 ± 5.1 mmHg. Arm slant angle was an independent predictor of the between-cuff SBP discrepancy (p = 0.003). Measurement with the pressure sensor showed a higher pressure under the rectangular compared to the conical cuff at any pressure level. The mean difference was −10.2 ± 5.2 mmHg and the difference progressively increased with increasing level of pressure applied to the cuffs. Conclusions: In obese people, the upper arm has a pronounced tronco-conical shape and rectangular cuffs may overestimate BP. Tronco-conical cuffs should be used for BP measurement in subjects with very large arms.

Orotracheal tube as arisk factor for lower respiratory tract infection: preliminary data from arandomised trial.

The aim of the study was to investigate whether polyurethane (PU) endotracheal tubes, continuous measurements of cuff pressure and aspiration of the subglottic space as a bundle of parameters could reduce patients' risk for developing ventilator associated pneumonia (VAP). Two groups of patients that differed only in terms of endotracheal tubes and intubation intervention were compared. GroupA was ventilated using PU tubes a with conical cuff; they also had continuous cuff pressure measurement and continuous subglottic aspiration. GroupB was ventilated using PVC tubes with a cylindrical cuff; the patients underwent intermittent cuff pressure measurement and intermittent subglottic aspiration. Seven patients in groupA (13.2%) and 18 in groupB (36.0%) out of 103 were diagnosed with VAP. VAP patients were in general older, stayed longer in the ICU and were ventilated significantly longer compared with the patients with no VAP. Eight more patients in groupB died compared with groupA. Moreover, subjects in groupA survived longer. Patient age, hours on mechanical ventilation, and days on an ICU were all positively associated with the occurrence of VAP. Prevention parameters in ventilation (PU cuff, conical cuff, continuous subglottic drainage and continuous cuff pressure measurement) could prevent the incidence of VAP in ICU patients.

Comparison of blood pressure measurements of anesthetized dogs obtained noninvasively with a cylindrical blood pressure cuff and an anatomically modified conical blood pressure cuff.

To compare blood pressure measured noninvasively with an oscillometric device that involved use of a novel conical cuff and a traditional cylindrical blood pressure cuff. 17 adult hound-type dogs. Dogs were anesthetized, and a 20-gauge, 1.5-inch catheter was inserted in the median sacral artery. The catheter was attached to a pressure transducer via fluid-filled noncompliant tubing, and direct blood pressure was recorded with a multifunction monitor. A specially fabricated conical cuff was placed on the antebrachium. Four sets of direct and indirect blood pressure measurements were simultaneously collected every 2 minutes. Four sets of measurements were then obtained by use of a cylindrical cuff. The cylindrical cuff met American College of Veterinary Internal Medicine consensus guidelines for validation of indirect blood pressure measurements for mean arterial blood pressure (MAP), systolic arterial blood pressure (SAP), and diastolic arterial blood pressure (DAP). The conical cuff met the consensus guidelines for difference of paired measurements, SD, and percentages of measurements within 10 and 20 mm Hg of the value for the reference method, but it failed a correlation analysis. In addition, although bias for the conical cuff was less than that for the cylindrical cuff for SAP, MAP, and DAP measurements, the limits of agreement for the conical cuff were wider than those for the cylindrical cuff for SAP and MAP measurements. On the basis of results of this study, use of a conical cuff for oscillometric blood pressure measurement cannot be recommended.

Impact of tracheal cuff shape on microaspiration of gastric contents in intubated critically ill patients: study protocol for a randomized controlled trial.

BackgroundVentilator-associated pneumonia (VAP) is the most common infection in intubated critically ill patients. Microaspiration of the contaminated gastric and oropharyngeal secretions is the main mechanism involved in the pathophysiology of VAP. Tracheal cuff plays an important role in stopping the progression of contaminated secretions into the lower respiratory tract. Previous in vitro studies suggested that conical cuff shape might be helpful in improving tracheal sealing. However, clinical studies found conflicting results. The aim of this study is to determine the impact of conical tracheal cuff shape on the microaspiration of gastric contents in critically ill patients.Methods/DesignThis prospective cluster randomized controlled crossover open-label trial is currently being conducted in ten French intensive care units (ICUs). Patients are allocated to intubation with a polyvinyl chloride (PVC) standard (barrel)-shaped or a PVC conical-shaped tracheal tube. The primary objective is to determine the impact of the conical shaped tracheal cuff on abundant microaspiration of gastric contents. Secondary outcomes include the incidence of microaspiration of oropharyngeal secretions, tracheobronchial colonization, VAP and ventilator-associated events. Abundant microaspiration is defined as the presence of pepsin at significant level (>200 ng/ml) in at least 30 % of the tracheal aspirates. Pepsin and amylase are quantitatively measured in all tracheal aspirates during the 48 h following inclusion. Quantitative tracheal aspirate culture is performed at inclusion and twice weekly. We plan to recruit 312 patients in the participating ICUs.DiscussionBEST Cuff is the first randomized controlled study evaluating the impact of PVC tracheal-cuff shape on gastric microaspirations in patients receiving invasive mechanical ventilation. Enrollment began in June 2014 and is expected to end in October 2015.Trial registrationClinicalTrials.gov Identifier: NCT01948635 (registered 31 August 2013).

Validation of a conical cuff on the forearm for estimating radial artery blood pressure

There has been a growing need for and interest in measuring noninvasive blood pressure (NIBP) in obese patients. In many situations, available rectangular upper arm blood pressure cuffs do not fit properly, closing in a crisscross manner or overlapping the elbow. To address this issue, GE Healthcare has designed a conically shaped cuff for use on the forearm to estimate radial arterial blood pressure. This study evaluated using this forearm cuff with an oscillometric NIBP algorithm compared with an invasive radial arterial blood pressure reference. Thirty-four patients were enrolled in the study with an aim to acquire a minimum of 150 paired measurements. Blood pressure was measured and recorded invasively from the radial artery of each patient, while noninvasive oscillometric measurements were acquired from the same limb using a conically shaped cuff placed on the patient's forearm. NIBP values were compared with the invasive blood pressure values acquired in the combined 30-s period preceding cuff inflation and the 30-s period following cuff deflation. The acceptance criteria for measurement accuracy were defined in accordance with the ANSI/AAMI/ISO 81060-2:2009 standard, which requires an absolute average error of 5 mmHg or less, with an SD of 8 mmHg or less. The systolic mean error (-0.82 mmHg) and SD (6.08 mmHg) and the diastolic mean error (1.53 mmHg) and SD (3.83 mmHg) were within the 81060-2 acceptance criteria. The statistical results show that oscillometric NIBP measurements taken with the conically shaped cuff placed on the forearm give an accurate estimation of radial arterial blood pressure.

Rectangular cuffs may overestimate blood pressure in individuals with large conical arms

Although the upper arm has the shape of a truncated cone, cylindrical cuffs and bladders are currently used for blood pressure (BP) measurement. The aim of this study was to ascertain whether cylindrical and tronco-conical cuffs provide different readings according to arm size and shape. We studied 220 individuals with arm circumference ranging from 22 to 42.5 cm. Four different cylindrical and four different tronco-conical bladders of appropriate size were used. Sequential same-arm measurements were performed in triplicate by two observers using the two cuffs in a random order. In 100 individuals, the actual pressure transmitted to the arm surface by the two cuffs at the central point was also measured. Upper arm shape was tronco-conical in all of the individuals. In a multiple regression, conicity was related to arm circumference (P < 0.001) and length (P = 0.001). Arm conicity and size were independently related to the between-cuff SBP (P = 0.001 and 0.002, respectively) and DBP (P = 0.001 and <0.001, respectively) discrepancies. In the group with arm circumference of 37.5-42.5 cm, the cylindrical cuff overestimated BP measured with the tronco-conical cuff by 2.0 ± 0.4/1.8 ± 0.3 mmHg (P = 0.001 and <0.001). In this group, 15% of individuals found hypertensive with the cylindrical cuff were normotensive when assessed with the conical cuff. Differences as great as 9.7/7.8 mmHg were found in individuals with large arms and slant angle equal to or less than 83°. In obese people, the upper arm may have a pronounced tronco-conical shape and cylindrical cuffs may overestimate BP. Tronco-conical cuffs should be used for BP measurement in individuals with large arms.

Accuracy of a single rigid conical cuff with standard-size bladder coupled to an automatic oscillometric device over a wide range of arm circumferences

Although the upper arm has the shape of a truncated cone, cylindrical cuffs and bladders are currently used for blood pressure (BP) measurement. The aims of this study were to describe upper arm characteristics and to test the accuracy of a standard adult-size conical cuff coupled to an oscillometric device over a wide range of arm circumferences. Arm characteristics were studied in 142 subjects with arm circumferences ranging from 22 to 45 cm (study 1). In a subset of 33 subjects with the same range of arm circumferences, a rigid conical cuff with standard-size bladder (12.6 × 24.0 cm) and a rigid cylindrical cuff (13.3 × 24.0 cm), both coupled to a Microlife BP A100 device, were tested according to the requirements of the protocol of the European Society of Hypertension (ESH; study 2). Study 1. In all subjects, upper-arm shape was tronco-conical with slant angles ranging from 89.5° to 82.2°. In a multiple linear regression analysis, only arm circumference was an independent predictor of conicity (P<0.001). Study 2. The rigid conical cuff passed all three phases of the ESH protocol for systolic and diastolic BPs. Mean device-observer BP differences obtained with the conical cuff were unrelated to arm circumference. When the rigid cylindrical cuff was used, ESH criteria were not satisfied, and the cuff overestimated systolic BPs in subjects with large arms. BP can be measured accurately with the use of a standard-size rigid conical cuff coupled to a BP A100 device for a wide range of arm circumferences.

Large cuff volumes impede posterior pharyngeal mucosal perfusion with the laryngeal tube airway.

The laryngeal tube airway (LTA) is a new extraglottic airway device with a large proximal cuff that inflates in the laryngopharynx and a distal conical cuff that inflates in the hypopharynx. We determine the influence of the cuff volume and anatomic location on pharyngeal mucosal pressures for the LTA. Fifteen fresh cadavers were studied. Microchip sensors were attached to the (anatomic location) anterior, lateral and posterior surface of the distal cuff (hypopharynx) and proximal cuff (laryngopharynx) of the size 4 LTA. Oropharyngeal leak pressure (OLP) and mucosal pressures were measured at 0-140 mL cuff volume in 20-mL increments. In addition, mucosal pressures for the proximal cuff were measured in three awake, topicalized volunteers. OLP and mucosal pressure at all locations increased with cuff volume (all: P < 0.01). Mucosal pressures were highest posteriorly. Mucosal pressures only exceeded 35 cm H(2)O (pharyngeal mucosal perfusion pressure) in the anterior and posterior laryngopharynx and when the cuff volume was > 80-100 mL. Mucosal pressures were similar for cadavers and awake volunteers. Mucosal pressures for the LTA increase with cuff volume, are highest posteriorly and potentially exceed mucosal perfusion pressure when cuff volume exceeds 80-100 mL.

Improved Design of a Pulse Duplicator to Study the Natural Heart Valves

A new design of a pulse duplicator is described using the principle of external compression of the heart with pulsating compressed air. For preparation, a conical cuff is cut from thin felt and adapted to the size and shape of the heart. The wider opening of the felt tube is sutured to the myocardium near the atrioventricular groove. The other end is closed by a plate carrying a gas inlet. The cuff is hardened by impregnation with a rapidly polymerizing plastic. Special care is taken not to distort the valve area. A felt bridge prevents bulging of the heart. The window connections for visualizing the valves are individually fixed and adapted. Cardiac function is fairly satisfactory in this pulse duplicator. In particular, valve movements are nearly normal, especially the systolic contraction of the mitral valve ring. Results of an analysis of this phenomenon are reported. The mechanism is inexpensive and disposable.