What is the Adequate Cuff Volume for Tracheostomy Tube? A Pilot Cadaver Study

Objective To determine the patterns of tracheostomy cuff pressure changes with various air inflation amounts in different types of tracheostomy tubes to obtain basic data for appropriately managing longterm tracheostomy.Methods We performed tracheostomy on a 46-year-old male cadaver. Three types of tracheostomy tubes (single-cuffed, double-cuffed, and adjustable flange), divided into 8 different subtypes based on internal tube diameters and cuff diameters, were inserted into the cadaver. Air was inflated into the cuff, and starting with 1 mL air, the cuff pressure was subsequently measured using a manometer.Results For the 7.5 mm/14 mm tracheostomy tube, cuff inflation with 3 mL of air yielded a cuff pressure within the recommended range of 20–30 cmH₂O. The 7.5 mm/24 mm tracheostomy tube showed adequate cuff pressure at 5 mL of air inflation. Similar values were observed for the 8.0 mm/16 mm and 8.0 mm/27 mm tubes. Double-cuffed tracheostomy cuff pressures (7.5 mm/20 mm and 8.0 mm/20 mm tubes) at 3 mL air inflation had cuff pressures of 18–20 cmH₂O at both the proximal and distal sites. For the adjustable flange tracheostomy tube, cuff pressure at 6 mL of cuff air inflation was within the recommended range. Maximal cuff pressure was achieved at inflation with almost 14 mL of air, unlike other tube types.Conclusion Various types of tracheostomy tubes showed different cuff pressures after inflation. These values might aid in developing guidelines For patients who undergo tracheostomy and are discharged home without cuff pressure manometers, this standard might be helpful to develop guidelines.

Complications Associated with the Use of Supraglottic Airway Devices in Perioperative Medicine

Supraglottic airway devices are routinely used for airway maintenance in elective surgical procedures where aspiration is not a significant risk and also as rescue devices in difficult airway management. Some devices now have features mitigating risk of aspiration, such as drain tubes or compartments to manage regurgitated content. Despite this, the use of these device may be associated with various complications including aspiration. This review highlights the types and incidence of these complications. They include regurgitation and aspiration of gastric contents, compression of vascular structures, trauma, and nerve injury. The incidence of such complications is quite low, but as some carry with them a significant degree of morbidity the need to follow manufacturers’ advice is underlined. The incidence of gastric content aspiration associated with the devices is estimated to be as low as 0.02% with perioperative regurgitation being significantly higher but underreported. Other serious, but extremely rare, complications include pharyngeal rupture, pneumomediastinum, mediastinitis, or arytenoid dislocation. Mild short-lasting adverse effects of the devices have significantly higher incidence than serious complications and involve postoperative sore throat, dysphagia, pain on swallowing, or hoarseness. Devices may have deleterious effect on cervical mucosa or vasculature depending on their cuff volume and pressure.

Postoperative Pharyngolaryngeal Adverse Events with Laryngeal Mask Airway (LMA Supreme) in Laparoscopic Surgical Procedures with Cuff Pressure Limiting 25 cmH2O: Prospective, Blind, and Randomised Study

To reduce the incidence of postoperative pharyngolaryngeal adverse events, laryngeal mask airway (LMA) manufacturers recommend maximum cuff pressures not exceeding 60 cmH2O. We performed a prospective randomised study, comparing efficacy and adverse events among patients undergoing laparoscopic surgical procedures who were allocated randomly into low (limiting 25 cmH2O, L group) and high (at 60 cmH2O, H group) LMA cuff pressure groups with LMA Supreme. Postoperative pharyngolaryngeal adverse events were evaluated at discharge from postanaesthetic care unit (PACU) (postoperative day 1, POD 1) and 24 hours after discharge from PACU (postoperative day 2, POD 2). All patients were well tolerated with LMA without ventilation failure. Before pneumoperitoneum, cuff volume and pressure and oropharyngeal leak pressure (OLP) showed significant differences. Postoperative sore throat at POD 2 (3 versus 12 patients) and postoperative dysphagia at POD 1 and POD 2 (0 versus 4 patients at POD 1; 0 versus 4 patients at POD 2) were significantly lower in L group, compared with H group. In conclusion, LMA with cuff pressure limiting 25 cmH2O allowed both efficacy of airway management and lower incidence of postoperative adverse events in laparoscopic surgical procedures. This clinical trial is registered withKCT0000334.

New Blood Pressure Measurement Method Using Waveform Features

The Ausculatory and the Oscillometric are the most commonly used blood pressure measurement methods worldwide. However, the ausculatory method requires professionally trained observers and is not suitable for automatic BP measurement; while the oscillometric method is less accurate in wide age groups. A new BP measurement method is introduced here which determines the subject’s BP value by features of the waveform measured by a strain sensor on the arm skin. During the cuff based measurement process, blood pulses in the brachial artery lead to artery deformations, which transfer to the arm surface in the form of surface strain and to the cuff in the form of cuff pressure oscillation. Since the cuff volume and amount of air keeps changing during the measurement, arm surface strain changes are more related to blood pulse. A piezoelectric film strain sensor is placed on the arm surface above the brachial artery to measure the surface strain. Since the artery closure statuses are different during the BP measurement process, the unique features of the measured waveform are observed in our previous study. Using these features, the subject’s BP can be determined. The analysis of these features and their relation to the subject’s BP are illustrated in this paper.

Abstract 627: Antisense Inhibition Of Angiotensinogen Reduces BP In Normotensive Sprague-Dawley Rats And Effectively Eliminates RAS-dependent BP Control In Hypertensive SHR Rats

Uncontrolled hypertension is an important contributor to stroke, myocardial infarction, heart failure and renal failure. Despite the armamentarium of antihypertensive therapeutics, there still exists a need for a novel agent effective in individuals with Resistant Hypertension (RHTN). Second generation antisense oligonucleotides (ASOs) are a novel therapeutic class of inhibitors that cause RNase H-mediated target mRNA degradation in organs such as the liver and kidneys. Experiments were conducted to determine the efficacy of ASO treatment targeting angiotensinogen (Agt). Normotensive Sprague-Dawley rats were given 10 - 80 mg/kg/wk of an Agt ASO for 4 weeks via subcutaneous injections. Dose-responsive reductions of liver Agt mRNA (20 - 96%), kidney Agt mRNA (40 - 75%) and plasma Agt (25 - 90%) were observed. BP, measured by tail-cuff volume-pressure recordings, was dose-dependently reduced by Agt ASO treatments as well. At the maximal ASO dose SBP, MAP and DBP were reduced by 39, 43 and 45 mm Hg, respectively. Studies comparing Agt ASO to captopril treatments were conducted in SHR rats. Agt ASO administered at 50, 75 or 100 mg/kg/wk for 2 weeks resulted in dose-dependent reductions of BP of 35 - 57 mm Hg (SBP), 32 - 52 mm Hg (MAP) and 31 - 49 mm Hg (DBP). Addition of 50 mg/kg/day of captopril did not result in further BP reductions in rats receiving 100 mg/kg/wk Agt ASO, suggesting maximal inhibition of RAS signaling was already achieved via Agt ASO treatment in this group. However, captopril treatment in the 50 and 75 mg/kg/wk Agt ASO treated groups did result in further reductions of 17 & 27 mm Hg (SBP), 17 & 25 mm Hg (MAP) and 17 & 24 mm Hg (DBP). These data demonstrate robust and predictive reductions of BP with long term Agt ASO treatment in normo- or hypertensive rats. Additionally, complete inhibition of RAS-dependent BP control could be achieved within 2 wks of ASO treatment. Finally, additive BP lowering was achieved with the combination treatment of Agt ASO and captopril, suggesting improvements in efficacy are possible when ASOs are added to existing RAS inhibitor therapeutics. Such improvements could be desirable in RHTN individuals and/or individuals not at their BP goal with existing RAS inhibitors.

Laryngopharyngeal complaints following short-term endotracheal intubation: peculiarities of males and females

Background. Laryngopharyngeal complaints are classified as minor post-intubation complications. They cause great discomfort, have some influence on the quality of life and can limit patient’s casual activity. The extent of complaints ranges from 12 to 65%. Undesirable complications can be avoided by ascertaining factors that are able to provoke or decrease laryngopharyngeal symptoms after endotracheal intubation. In this study, we assessed predominant laryngopharyngeal symptoms following a short-term endotracheal intubation and their peculiarities subject to gender, and we estimated the most important influencing factors. Materials and methods. 218 patients were examined before endotracheal anesthesia, 1–2 and 24 hours after extubation. The following laryngopharyngeal complaints were recorded: hoarseness, vocal fatigue, globus pharyngeus, throat pain and throat clearing. These factors were also assessed in relation to endotracheal intubation parameters: endotracheal tube size, cuff volume and pressure, number of intubation attempts, length of anesthesia, experience of anesthesiologist and additional parameters: smoking, allergy, GERD symptoms, laryngitis and singing skills subject to gender. Results. All laryngopharyngeal symptoms increased significantly in 2 hours after extubation and remained increased after 24 hours in both male and female groups. In 1–2 hours after extubation, females complained of throat pain more than males (61.3 vs. 42.9%; p = 0,014). The following significant relations were found 1–2 hours after extubation: between throat pain and length of anesthesia, globus pharyngeus and tube size and cuff volume in the male group; between globus pharyngeus, vocal fatigue and smoking, throat clearing and cuff volume in the female group. After 24 hours, the relation was noticed between vocal fatigue and cuff volume and number of intubation attempts, globus pharyngeus and length of anesthesia, between hoarseness and number of intubation attempts and between throat pain and singing skills in the male group. Some relation between throat clearing and cuff volume remained for 24 hours after extubation, smoking had influence on hoarseness and vocal fatigue in the female group. Conclusions. Laryngopharyngeal symptoms remain an important cause of discomfort for 24 hours after extubation. Females complain of laryngeal and pharyngeal symptoms more than males and throat pain following extubation is also more frequent in females. The most important parameters of short-term endotracheal intubation that influence laryngopharyngeal complaints are as follows: cuff volume, length of anesthesia and number of intubation attempts that affect males more than females. Smoking affects females more, though singing skills are more significant in the male group.