Comparative study of the reliability of ultrasound to confirm the position of endotracheal tube with cuff inflated with saline versus air

Aim: To compare the reliability of transtracheal ultrasound to confirm the endotracheal tube position with saline versus air inflated cuff. Methods: This was a prospective randomized cadaveric study. Four techniques were randomized: endotracheal tube in the trachea with air or saline inflated cuff, and endotracheal tube in the esophagus with air or saline inflated cuff. The investigator used the Mcgrath to randomly place the endotracheal tube in the trachea or in the esophagus with saline or air inflated cuff. During the first series of measurements, nine residents performed transtracheal ultrasound with linear transducer placed transversely at the suprasternal notch. They were recorded with a cut off fixed to 30 seconds, and a questionnaire was completed by the residents after each transtracheal ultrasound in order to report where the endotracheal tube is positioned according to them. The second series followed the same protocol and included three residents who had participated in the first series. The primary outcome was the success rate in determining the position of the endotracheal tube. Results: In the first series, the success rate was 46.5%. In the second series, the success rate was 72.9%. There was no significant difference between cuff inflated with saline and air (p = 1.00). The overall mean time required was 20.6 s (95% CI 13.0–28.2 s). Based on an empirical data set, transtracheal ultrasound had a sensitivity of 62.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 26.08%. Conclusion: This investigation shows that regardless of the contents of the endotracheal tube cuff, the use of transtracheal ultrasound to confirm the position of endotracheal tube reports disappointing results.

Somatosensory Testing in Pediatric Patients with Chronic Pain: An Exploration of Clinical Utility

We aimed to evaluate the utility of clinical somatosensory testing (SST), an office adaptation of laboratory quantitative sensory testing, in a biopsychosocial assessment of a pediatric chronic somatic pain sample (N = 98, 65 females, 7–18 years). Stimulus–response tests were applied at pain regions and intra-subject control sites to cutaneous stimuli (simple and dynamic touch, punctate pressure and cool) and deep pressure stimuli (using a handheld pressure algometer, and, in a subset, manually inflated cuff). Validated psychological, pain-related and functional measures were administered. Cutaneous allodynia, usually regional, was elicited by at least one stimulus in 81% of cases, most frequently by punctate pressure. Central sensitization, using a composite measure of deep pressure pain threshold and temporal summation of pain, was implied in the majority (59.2%) and associated with worse sleep impairment and psychological functioning. In regression analyses, depressive symptoms were the only significant predictor of pain intensity. Functional interference was statistically predicted by deep pressure pain threshold and depressive symptoms. Manually inflated cuff algometry had comparable sensitivity to handheld pressure algometry for deep pressure pain threshold but not temporal summation of pain. SST complemented standard biopsychosocial assessment of pediatric chronic pain; use of SST may facilitate the understanding of disordered neurobiology.

Determining correct tracheal tube insertion depth by measuring distance between endotracheal tube cuff and vocal cords by ultrasound in Chinese adults: a prospective case-control study

ObjectivesUnrecognised malposition of the endotracheal tube can lead to severe complications in patients under general anaesthesia. The purpose of this study was to verify the feasibility of using ultrasound to measure the distance between the upper edge of saline-inflated cuff and the vocal cords.DesignProspective case-control study.SettingA tertiary hospital in Beijing, China.MethodsIn this prospective study, 105 adult patients who required general anaesthesia were enrolled. Prior to induction, ultrasound was used to identify the position of the vocal cords. After intubation, the endotracheal tube (ETT) was fixed at a depth of 23 cm at the upper incisors in men and 21 cm in women. The depth of intubation was verified by video-assisted laryngoscopy. The distance between the upper edge of the saline-inflated cuff and the vocal cords was measured by ultrasound; the ideal distance was considered to be 1.9–4.1 cm.ResultsAmong the 105 cases, two cuffs were too close to the vocal cords and one too far away from the vocal cords. These diagnoses were made by ultrasound and were in agreement with results from direct laryngoscopy. The overall accuracy of ultrasound in identifying malposition of the cuff was 100.0% (95% CI: 96.6% to 100%). The sensitivity, specificity, positive predictive value and negative predictive value of ultrasound were, respectively, 100% (95% CI: 96.5% to 100%), 100% (95% CI: 29.2% to 100%), 100% (95% CI: 96.5% to 100%) and 100% (95% CI: 29.2% to 100%).ConclusionIdentification of the upper edge of the saline-inflated cuff and the vocal cords by ultrasound to assess the location of the ETT is a reliable method. It can be used to avoid malposition of the ETT cuff and reduce the incidence of vocal cords injury after intubation.Trial registration numberChiCTR-DDD-17011048.

Abstract 13993: Soluble CD146 is a Marker of Peripheral Congestion in Global Heart Failure Patients

Introduction: CD146 is a component of the endothelial junction. We previously showed that its soluble form (sCD146) is as powerful as plasma natriuretic peptides to detect cardiac origin of acute dyspnea. The source of plasma sCD146 in heart failure (HF) is however unknown. Hypothesis: We make the hypothesis that peripheral venous congestion (VC), a typical sign of global ventricular failure, might be the source of increased sCD146. Methods: A total of 44 outpatients with heart failure, NYHA functional class II or III, and LVEF <40%, no evidence of VC on physical exam and on stable medical therapy were studied. Patients gave informed consent. To experimentally model VC, venous arm pressure was increased to 30 mmHg above baseline by inflating a pressure cuff around the dominant arm. Blood was sampled from test and control arm (lacking an inflated cuff) before and after 90 minutes of venous congestion. Plasma concentrations of sCD146 were determined by ELISA. Values are expressed as mean ± SEM and groups were compared with paired-samples t-test. Results: The age of the study cohort was 54±2 years, 32% were female, 32% had an ischemic etiology and the LVEF was 22±1%. The induction of VC was associated with an increase in circulating levels of sCD146 in the congested arm when compared to baseline (506±33 vs 463±33 ng/ml, p=0.001) and to control arm (476±32 ng/ml, p=0.035). In contrast, no significant increase occurred in the control arm when compared to baseline values (Figure). Conclusions: Plasma sCD146 acutely increases in response to experimental peripheral VC. sCD146 could be particularly useful to titrate diuretic treatment in HF patients with global heart failure, possibly preventing end-organ dysfunction and damage from severe and/or long-standing peripheral VC.

Short-term pressure induced suppression of the short-latency response: a new methodology for investigating stretch reflexes

During experiments involving ischemic nerve block, we noticed that the short-latency response (SLR) of evoked stretches in m. soleus decreased immediately following inflation of a pneumatic cuff surrounding the lower leg. The present study aimed to investigate this short-term effect of pressure application in more detail. Fifty-eight healthy subjects were divided into seven protocols. Unilateral stretches were applied to the calf muscles to elicit a SLR, and bilateral stretches to evoke a subsequent medium-latency response (MLR). Furthermore, H-reflexes and sensory nerve action potentials (SNAPs) were recorded. Additionally, stretches were applied with different velocities and amplitudes. Finally, the SLR was investigated during hopping and in two protocols that modified the ability of the muscle-tendon complex distal to the cuff to stretch. All measurements were performed with deflated and inflated cuff. Results of the protocols were as follows: 1) inflation of the cuff reduced the SLR but not the MLR; 2) the H-reflex, the M-wave, and, 3) SNAPs of n. tibialis remained unchanged with deflated and inflated cuff; 4) the SLR was dependent on the stretch velocity with deflated and also inflated cuff; 5 and 6) the reduction of the SLR by the cuff was dependent on the elastic properties of the muscle-tendon complex distal to the cuff; and 7) the cuff reduced the SLR during hopping. The present results suggest that the cuff did not affect the reflex arc per se. It is proposed that inflation restricted stretch of the muscles underlying the cuff so that most of the length change occurred in the muscle-tendon complex distal to the cuff. As a consequence, the muscle spindles lying within the muscle may be less excited, resulting in a reduced SLR. Due to its applicability in functional tasks, the introduced method can be a useful tool to study afferent feedback in motor control.

Pharyngolaryngeal, Neck, and Jaw Discomfort after Anesthesia with the Face Mask and Laryngeal Mask Airway at High and Low Cuff Volumes in Males and Females

Background There is controversy over (1) the relative incidence of sore throat between the face mask (FM) and laryngeal mask airway (LMA), (2) the efficacy of LMA intracuff pressure reduction as a mechanism for minimizing sore throat, and (3) the relative incidence of sore throat with the LMA between males and females. In a randomized double-blind study, the authors compared laryngopharyngeal, neck, and jaw discomfort with the FM and LMA at high and low cuff volumes in males and females. Methods Three hundred adult patients were randomly assigned to three equal-sized groups for airway management: (1) the FM, (2) the LMA with a fully inflated cuff (LMA-High), or (3) the LMA with a semi-inflated cuff (LMA-Low). Anesthesia was administered with propofol, nitrous oxide, oxygen, and isoflurane. In the FM group, a Guedel-type oropharyngeal airway and jaw thrust were used only if necessary. In the LMA groups, cuff inflation was achieved with either 15 or 30 ml for the size 4 (females) and 20 or 40 ml for the size 5 (males). The LMA was removed when the patient was awake. Patients were questioned 18-24 h postoperatively about surgical pain, sore throat, sore neck, sore jaw, dysphonia, and dysphagia, and about whether they were satisfied with their anesthetic. Results The incidence of sore throat was lower in the FM (8%) than the LMA-High (42%) and LMA-Low (20%) groups (both: P &lt; or = 0.02). The incidence of sore neck was higher for the FM (14%) than the LMA-High group (6%; P = 0.05) but similar to the LMA-Low group (8%). The incidence of sore jaw was higher in the FM (11%) than the LMA-High (3%) and LMA-Low (3%) groups (both: P = 0. 02). There were no differences among groups for surgical pain or dysphonia. The incidence of dysphagia was lower in the FM (1%) than the LMA-High group (11%; P = 0.003), but similar to the LMA-Low group (1%). The incidence of sore throat and dysphagia was lower in the LMA-Low group than the LMA-High group for both males and females (all: P &lt; or = 0.04). There were no differences in discomfort levels between males and females in any group. Two patients from the FM group and one from the LMA-High group were not satisfied with their anesthetic. These complaints were unrelated to postoperative morbidity. Conclusion The LMA causes more sore throat and dysphagia but less jaw pain than the FM. Sore throat and dysphagia are more common with the LMA if the initial cuff volume is high. There are no differences in discomfort levels between males and females. However, these discomforts do not influence patient satisfaction after LMA or FM anesthesia.

Femoral arterial injection of adenosine in humans elevates MSNA via central but not peripheral mechanisms

MacLean, D. A., B. Saltin, G. Rådegran, and L. Sinoway. Femoral arterial injection of adenosine in humans elevates MSNA via central but not peripheral mechanisms. J. Appl. Physiol. 83(4): 1045–1053, 1997.—The purpose of the present study was to examine the effects of femoral arterial injections of adenosine on muscle sympathetic nerve activity (MSNA) under three different conditions. These conditions were adenosine injection alone, adenosine injection after phenylephrine infusion, and adenosine injection distal to a thigh cuff inflated to arrest the circulation. The arterial injection of adenosine alone resulted in a fourfold (255 ± 18 U/min) increase above baseline (73 ± 12 U/min; P< 0.05) in MSNA with an onset latency of 15.8 ± 0.8 s from the time of injection. The systemic infusion of phenylephrine resulted in an increase ( P < 0.05) in mean arterial pressure of ∼10 mmHg and a decrease ( P < 0.05) in heart rate of 8–10 beats/min compared with baseline values before phenylephrine infusion. After adenosine injection, the onset latency for the increase in MSNA was delayed to 19.2 ± 2.1 s and the magnitude of increase was attenuated by ∼50% (123 ± 20 U/min) compared with adenosine injection alone ( P < 0.05). When a cuff was inflated to 220 mmHg to arrest the circulation and adenosine was injected into the leg distal to the inflated cuff, there were no significant changes in MSNA or any of the other measured variables. However, on deflation of the cuff, there was a rapid increase ( P < 0.05) in MSNA, with an onset latency of 9.1 ± 0.9 s, and the magnitude of increase (276 ± 28 U/min) was similar to that observed for adenosine alone. These data suggest that ∼50% of the effects of exogenously administered adenosine are a result of baroreceptor unloading due to a drop in blood pressure. Furthermore, the finding that adenosine did not directly result in an increase in MSNA while it was trapped in the leg but that it needed to be released into the circulation suggests that adenosine does not directly stimulate thin fiber muscle afferents in the leg of humans. In contrast, it would appear that adenosine exerts its effects via some other chemically sensitive pool of afferents.