Cuff deflation

The blood pressures are measured by a sphygmomanometer, an instrument consisting of a stethoscope and an inflatable cuff connected to a tube of mercury called a manometer. After the cuff is wrapped around the upper arm, it is pumped up with air until it cuts off the flow of blood. With the stethoscope over the artery, the air is slowly released from the cuff, decreasing the pressure on the artery. When the blood flow first starts again in the artery, a noise can be heard through the stethoscope signifying the systolic blood pressure as the pressure shown on the manometer. As air continues to be released, the cuff deflates until no sound is heard in the artery. 

If cuff deflation is complicated by sialorrhea anticholinergic medications, such as scopolamine, glycopyrrolate, or amitriptyline may be used. Sublingual, 1% ophthalmic atropine, 1 to 4 drops up to q.i.d. is also effective (65), unless narrow angle closure glaucoma is present. 

Prior to cuff deflation it is preferable to switch to a home volume ventilator set for patient s comfort and adequate minute ventilation, with note taken of the peak airway pressure (Paw) Suctioning through the mouth and through the tracheostomy is necessary. With the cuff deflated, brief suctioning or use of the MIE may also be necessary. The Paw falls as the cuff is deflated, so the delivered volume should be increased to reach the previously observed Paw- Respiratory rate may need to be increased temporarily to improve patient comfort. Glottic function may require a few days to recover. Sa02 should be maintained at >90%. 

Once cuff deflation is tolerated comfortably, a Passy-Muir valve (PMV) should be added in-line, directly onto or close to the tracheostomy. Progressive hyperinflation from... 

Careful patient selection prevents unsafe levels of alveolar hypoventilation with subsequent hypoxemia and hypercapnea, especially if the tidal volume leakage is >20%. Any compensatory increase in respiratory rate and shortened expiratory time, attributable to the air leakage, may aggravate dynamic hyperinflation, especially among patients with airflow obstruction (15). Ventilator-supported speech has been reported in patients with neuromuscular diseases (NMD) and intact bulbar function (16-19). The physiologic characteristics that enable this population to tolerate ventilator-supported speech include little or no decrease in chest wall or lung compliance and the absence of airflow obstmction. Therefore, patients with NMD may be ventilated with a deflated or cuffless tracheostomy tube accepting the modest compromise in alveolar ventilation (16,20-22). Patient populations, such as those with chronic obstructive pulmonary disease may be able to tolerate cuff deflation for short periods provided there is adequate supervision. 

The third condition is the creation of an effective and adjustable air leak channel during tracheostomy cuff deflation. An effective channel has a lower impedance compared to the tracheostomy tube and exhalation HMB, in order to allow airflow to reach the vocal cords. If the impedance is too high, exhaled volume is diverted to the tracheostomy tube... 

The ability to communicate ensures that basic needs are met, preserves autonomy, and is a means of survival and safety. The inability of MV patients to communicate has the potential to result in anxiety, loss of control, and social isolation. If natural speech cannot be restored, then it is necessary to use methods that supplement or replace natural speech. For this purpose, an understanding of the anatomy of speech and language is essential. Ventilator-supported speech requires careful patient selection for those who can tolerate cuff deflation... 

Daily trials of cuff deflation and PMV extended if patient is coping, ensure PMV is out and cuff is inflated at night and during day rest, encourage phonation when PMV is in situ. 

The beauty of the mercury manometer is that you can assess its accuracy by simply looking at it. If the mercury meniscus is at zero when there is no pressure in the cuff and the column moves smoothly with inflation and deflation it is accurate and can be used as the gold standard for pressure measurement. All other devices must be calibrated against a... 

To test blood pressure, the doctor or another health professional inflates a cuff placed around the arm above the elbow. He or she then listens for specific sounds through a stethoscope placed at the crook of the elbow as the cuff is gradually deflated. The first of those sounds signals the time the heart beats and the fifth and final sound notes the heart at rest between beats. The pressure at the time of those two sounds is noted in a column of mercury similar to that in a thermometer, on a device called a sphygmomanometer, which is frequently mounted on the wall. The first, beating pressure... 

So try this experiment for yourself. Sit down with the blood pressure monitor in place, the cuff around your upper arm. Push the button, take your blood pressure reading, and make a note of it. Now close your eyes for two to three minutes, and concentrate on breathing in and out, slowly and deeply. Imagine your chest as an inflating and deflating balloon. After that two- to three-minute breathing exercise, take your blood pressure again. You ll be amazed at the improvement. 

Intravenous. A double cuff is applied to the arm, inflated above arterial pressure after elevating the limb to drain the venous system, and the veins filled with local anaesthetic, e.g. 0.5-1% lidocaine without adrenaline (epinephrine). The arm is anaesthetised in 6-8 min, and the effect lasts for up to 40 min if the cuff remains inflated. The cuff must not be deflated for at least 20 minutes. The technique is useful in providing anaesthesia for the treatment of injuries speedily and conveniently, and many patients can leave hospital soon after the procedure. The technique must be meticulously conducted, for if the full dose of local anaesthetic is accidentally suddenly released into the general circulation severe toxicity and even cardiac arrest may result. Bupivacaine is no longer used for intravenous regional anaesthesia as cardiac arrest caused by it is particularly resistant to treatment. Patients should be fasted and someone skilled in resuscitation must be present. 

In a study of 10 healthy subj ects, prolonged muscle weakness and symptoms of local anaesthetic toxicity were experienced after deflation of the tourniquet when 40 mL of prilocaine 0.5% and mivacurium 600 micrograms were used together for intravenous regional anaesthesia of the forearm. Giving prilocaine or mivacurium alone did not produce these effects. The slow recovery suggested that mivacurium was not broken down in the ischaemic limb, but inhibition of plasma cholinesterase by prilocaine would not fully explain the prolonged weakness once the cuff was deflated. ... 

Qregoretti C, Squadrone V, Fogliati C, et al. Trans-tracheal open ventilation in acute respiratory failure secondary to severe COPD exacerbation. Am J Respir Crit Care Med 2006 173 877-881. Bach JR, Alba AS. Tracheostomy ventilation. A study of efficacy with deflated cuffs and cuffless tubes. Chest 1990 97 679-683. 

Bach JR, Alba AS. Tracheostomy ventilation study of efficacy of deflated cuffs and cuffless tubes. Chest 1990 97 679-683. 

The channel s impedance is mainly affected by the tracheal diameter in relation to the outer diameter of the tracheostomy tube and the added resistance of the volume of the deflated floppy cuff (Fig. 5). 

Suction subglottic secretions before deflating tracheostomy cuff... 

Deflate cuff, remove inner tube, cork tracheostomy with size 4.0, attach mask to ventilator tubing, and apply by hand or secure with straps. Encourage slow deep breathing while observing for signs of distress, reconnect after 5 min and reinflate cuff. 

Endotracheal intubation Keep cuff pressure optimal aspirate subglottic secretions before deflating cuff IB C... 

Further deflation of the cuff leads to several more Korotkoff sounds, ultimately ending in silence as the pressure in the cuff drops below the diastolic blood pressure. The disappearance of sound determines the lower of the two readings that comprise a blood pressure measurement—the diastolic reading. The diastolic reading corresponds to the cycle where the heart is relaxing following its contraction. 

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