Care of the Ventilator Patient

Chapter 216 Care of the Ventilator Patient



Monica C. Clare, VMD, DACVECC



KEY POINTS



• Ventilator patient care requires specialized equipment, extensive monitoring, and dedicated, trained staff.

• Inadequate care can lead to life-threatening complications for the ventilator patient.

• Oropharyngeal bacterial colonization is a leading cause of ventilator-associated pneumonia and can be minimized by strict adherence to oral care protocols.

• Maintenance of airway hygiene is essential; anything entering the upper airway, such as endotracheal tubes or suction catheters, should be sterile.


INTRODUCTION


Mechanical ventilation is becoming more common in small animal medicine. These patients are usually anesthetized and are totally dependent on their caregivers. The major complications seen in ventilator patients can be minimized or prevented with appropriate nursing care and dedicated, trained caregivers. The challenges of caring for short-term (1 to 24 hours) and long-term (days to weeks) ventilator patients are different. Short-term ventilator patients may not require such specialized equipment or intensive care, but those being ventilated over a long term may have unique management requirements. Detailed patient records are essential, and a ventilator record sheet is often helpful (Box 216-1).



Box 216-1 Sample Ventilator Patient Treatment Sheet



• Evaluate and record ventilator settings q2h

• Monitor depth of anesthesia and adjust infusions q2h

• Suction endotracheal tube and instill saline if needed q4h

• Adjust tube ties and cuff q4h

• Clean tracheostomy tube cannula and site q4h

• Change endotracheal tube q24-48h

• Turn patient, record position, and check padding and heat support q4h

• Do passive range-of-motion exercises q4h

• Lubricate eyes q2h

• Flush and suction mouth and pharynx q4h

• Clean mouth with oral chlorhexidine solution q4h

• Reposition pulse oximetry probe and wrap tongue with saline or glycerine gauzes q2h

• Palpate bladder and measure urine output q4h

• Provide urinary catheter care q8h

• Perform intravenous catheter care q24h

• Change heat and moisture exchanger and ventilator tubing q48-72h

• Monitor continuously and record the following values q2h
• Electrocardiogram (heart rate and rhythm)

• Blood pressure (direct, Doppler, or oscillometric)

• Pulse oximeter

• End-tidal carbon dioxide

• Rectal temperature

• Central venous pressure

In one small animal study of long-term ventilation, many of the complications seen were related to nursing care issues, including endotracheal (ET) tube occlusion and accidental disconnections, tracheal necrosis, oral and ocular ulcers, pressure sores, muscle atrophy, and peripheral edema.1 This chapter reviews basic concepts in ventilator patient care.



AIRWAY



Intubation


Airway management is an essential aspect of ventilator patient care. For most patients this is accomplished via ET intubation and general anesthesia. It is important that ET tubes are sterile and ideally have high-volume, low-pressure cuffs. Tracheal mucosal blood flow can be occluded by pressures over 25 to 35 mm Hg.2 Ideally cuff pressure should be maintained between 20 and 25 mm Hg and measured regularly with a pressure gauge. Higher pressures impede mucosal blood flow and may lead to tracheal necrosis. Lower cuff pressures are associated with an increased risk of aspiration.2-4 In practice, the cuff should be inflated while auscultating the trachea until no leak is heard and then deflated slightly until a small leak can first be detected. Although frequently used, the pilot balloons do not correlate well with cuff pressure and should not be used as an indicator of appropriate inflation.3


Tracheal injury can also be minimized by repositioning the ET tube every 4 hours. This is achieved by deflating the cuff, repositioning the tube slightly to change the pressure point, and then reinflating the cuff. The mouth and pharynx should be flushed and suctioned before deflating the cuff.3


ET tubes should be tied securely with intravenous tubing or another nonporous material, which is less likely than gauze to become saturated with oral secretions and bacteria. The ties should be moved and secured in a different position every 4 hours to prevent lip necrosis.


The ET tube should be changed every 24 to 48 hours depending on the amount and character of the secretions. It is important to preoxygenate with 100% oxygen before changing the tube and to be prepared for a difficult reintubation.3 Sterile ET tubes should be used in all ventilator patients.


Patients such as those with neurologic or neuromuscular disease that cannot fight mechanical ventilation often can be managed with a tracheostomy tube and light sedation instead of ET intubation and general anesthesia. This may provide the benefits of allowing ongoing neurologic evaluation, decreased need for anesthesia, and the ability of some patients to eat and drink on their own while being ventilated.5 It is important to consider that some of these patients may require anxiolytic and/or analgesic drugs to control associated distress or discomfort associated with mechanical ventilation.3,5


Tracheostomy tubes ideally should have an inner cannula that should be cleaned every 4 hours and the entire tracheostomy tube changed every 24 to 48 hours. If there is no cannula, the tube should be suctioned regularly and changed every 24 hours. The tracheostomy tube should also have a cuff to protect the airway from migration of oral secretions and to allow positive end-expiratory pressure (PEEP) to be used.2,3



Humidification and Suction


Anesthetized patients are not able to cough or clear airway secretions effectively, and occlusion of the tube lumen is a common and potentially life-threatening problem.1 Prevention of airway occlusion requires adequate humidification and suctioning.


Gas flow bypasses the nasal passages during mechanical ventilation and is therefore not humidified or filtered by the body. This can lead to a loss of heat and moisture, which can damage the respiratory epithelium. Humidification is also critical in making secretions less viscous and easier to remove.2,3,6


Humidifiers can be divided broadly into two groups: high flow and passive. High-flow humidifiers are connected to the ventilator circuit and generally involve a heated element and a sterile water reservoir to add moisture and heat to the gases. These humidifiers are expensive but are very effective. It is important to monitor the respiratory circuit for excessive condensation or heat.


A less expensive method uses heat and moisture exchangers (HME) that act as an “artificial nose.” These devices trap exhaled water particles and heat as condensation during exhalation, helping to conserve airway moisture. Specialized filters also trap exhaled bacteria and viruses. The effectiveness of these devices depends on gas flow rates and the patient’s temperature. They should be changed every 24 to 72 hours or if they become saturated with secretions, because this creates resistance to gas flow. HMEs are not recommended in patients who are hypothermic or who have thick and copious secretions.2


Suctioning is another critical aspect of airway management. There are risks associated with this procedure, and proper technique must be followed. The inhaled oxygen concentration should be increased to 100% before and during suctioning. Monitoring of the patients oxygenation status with pulse oximetry throughout the procedure is recommended.


The suction catheter should be sterile, soft, and flexible, with more than one distal opening and a proximal thumbhole to control the level of suction. Sterile gloves should be worn and sterile technique observed throughout the procedure. Closed suction systems are also available and are helpful in maintaining sterility and preventing problems associated with tubing disconnection.


Suction should be applied while withdrawing the catheter from the airway for no more than 5 seconds at a time. This procedure can be repeated two or three times as long as oxygenation remains adequate and the patient does not seem distressed. If suctioning is productive, it can be performed as frequently as every 2 to 4 hours. The risks of suctioning include hypoxemia, patient discomfort, damage to the tracheal mucosa, collapse of small airways and alveoli, and contamination of the lower airways.2,3,6


If the secretions are too dry to suction well or adequate humidification is not being provided, small aliquots of sterile saline (0.2 ml/kg) may be instilled into the airway before suctioning. This practice has been challenged because of the lack of evidence of beneficial effects coupled with the risk of introducing infection.2,6


Ventilator circuit tubing is a potential source of nosocomial infection and should be replaced every 48 to 72 hours. Tubing should be sterile.2

Related posts:

  1. Deteriorating Mental Status
  2. Hyperthermia and Fever
  3. Ventilator-Associated Lung Injury
  4. Allergic Airway Disease in Dogs and Cats and Feline Bronchopulmonary Disease

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Care of the Ventilator Patient

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