STUDY OBJECTIVE: To evaluate the effectiveness of methods for sealing a small endotracheal tube cuff perforation. DESIGN: Randomized evaluation in an in vitro model of mechanical ventilation. In addition, two pertinent cases are reported. SETTING: Operative anesthesia service in a large tertiary referral center. INTERVENTIONS: A transparent acrylic "trachea" attached to a rubber breathing bag ("lung") was intubated with an 8.0 mm endotracheal tube. Positive pressure mechanical ventilation was begun and baseline minute ventilation recorded. After equilibrium, the endotracheal tube cuff was perforated in a standard fashion, and one of four "treatments" was applied in random sequence. Group A endotracheal tubes (n = 7) were managed by increasing fresh gas flow and manually injecting air into the cuff. Group B cuffs (n = 8) were insufflated with oxygen to maintain cuff pressure at 25 to 28 mmHg. In Groups C (n = 8) and D (n = 9), an 8 ml mixture of 2% lidocaine hydrochloride jelly (Xylocaine, Astra, Westborough, MA), and saline was injected into the cuff at a dilution of 1:3 and 1:1, respectively. MEASUREMENTS AND MAIN RESULTS: Measurements included minute ventilation, airway pressure, and intracuff pressure. During the 30-minute observation period after cuff perforation, total exhaled ventilation was assessed and wasted ventilation calculated. Group A wasted ventilation (means +/- SD) was significantly greater (112 +/- 20 liters, p less than 0.01) than Groups B, C, and D (12 +/- 12 liters, 10 +/- 5 liters, and 18 +/- 13 liters, respectively). In Group A, it was impossible to maintain adequate minute ventilation. To remain inflated, Group B cuffs required insufflation at a rate of 10 to 80 ml/min. Groups C and D maintained an excellent cuff seal, but 2 of 9 Group D cuffs could not be deflated, while all Group C cuffs were deflatable. Also reported are two cases of persistent intraoperative endotracheal tube cuff leaks refractory to conventional management. Inflation of the endotracheal tube cuff with a lidocaine jelly-saline mixture successfully eliminated the leak, allowing completion of the procedure without reintubation. CONCLUSIONS: The authors' in vitro results, in conjunction with the observations from their two cases, suggest that lidocaine jelly mixed with 1 to 3 parts normal saline may be useful in managing certain types of endotracheal tube cuff incompetence.

Equipment Failure↗

PubMedDate not supplied

Experimental aortic stenosis and corresponding left ventricular hypertrophy in sheep.

Left ventricular hypertrophy (LVH) is an independent cardiac risk factor. A simple standard experimental model of inducing LVH for further studies using experimental aortic stenosis in sheep was performed. The aim of this study is to describe animal-specific requirements as well as perioperative therapy, postoperative care, and the use of echocardiography for routine follow-up examinations. Supracoronary aortic banding was performed in 55 female sheep at an age of 6 to 8 months. General anesthesia and an antero-lateral thoracotomy were used. The objective was to achieve pressure gradients of 20 to 30 mm Hg. In addition a 4th intercostal space rib window was created to improve echocardiographic vision. The operations were completed successfully in all animals. Intraoperatively, little severe arrhythmia occurred. During the follow-up interval of 8 +/- 1.3 months, 8 animals died, due to incomplete perforation of the ascending aorta (3), chronic heart failure (2), pericardial cyst (1), and respiratory failure and infection (2). All remaining animals were amenable for further studies. Severe LVH was diagnosed with routine echocardiography on follow-up. Thus, experimental aortic stenosis in sheep is a safe and relatively simple technique to generate stable LVH. Echocardiography is an easy tool for follow-up evaluations. Due to low complication rates, the sheep model is well suited for further research in LVH.

Animals↗

PubMedDate not supplied

Age-dependent expression of advanced glycation end product receptor genes in the human heart.

BACKGROUND: Advanced glycation end products (AGEs) are formed by the reaction of sugars and NH2 groups of lysine and arginine residues and have been shown to accumulate in tissues, including the heart, with normal ageing. The interaction of AGEs with their receptors is known to cause changes in cell function, leading, for example, to the production of pro-inflammatory cytokines and free radicals. OBJECTIVE: This study investigated the gene expression of the five known AGE receptors: AGE-R1, AGE-R2, AGE-R3, the scavenger receptor II, and the receptor for AGEs (RAGE) in human heart tissue. METHODS: Tissue samples were taken from the right cardiac auricles from three patient groups: children (2.4 +/- 1.1 years), adults (45.3 +/- 0.8 years) and elderly subjects (76.4 +/- 0.4 years). Analysis of gene expression of the five AGE receptors was performed using the reverse transcription-polymerase chain reaction (RT-PCR) and 18S mRNA levels as loading controls. RESULTS: Our results show an age-dependent upregulation of the genes for AGE-R3 and the scavenger receptor II, but a downregulation for RAGE and no significant differences for AGE-R1 and AGE-R2. CONCLUSION: This study supports a pathophysiological function for AGE receptors such as AGE-R3 and RAGE in the ageing heart.

Adult↗