Optimal Care for Ventilator Patients

Many health care providers are unaware that the recognition of acute respiratory distress syndrome (ARDS) in 1967 was a key factor in crafting intensive care units (ICUs) as they are known today. ARDS is the most devastating condition underlying respiratory distress or failure. It causes calamitous pneumonia, shock, sepsis, and severe distress in ~150,000 people annually, the majority of whom have had no previous lung disease.^1,2 Other conditions associated with respiratory distress or failure include cardiovascular disease (valvular disease, coronary atherosclerosis, postoperative coronary care); neurologic disorders (cerebrovascular accident, subarachnoid hemorrhage, spinal cord injuries, Lou Gehrig's disease); and chronic obstructive pulmonary disease and pneumonia.^3,4

Mechanical ventilation is now a standard intervention for respiratory failure.⁵ Historically, 40% to 70% of patients on mechanical ventilation died. Few patients regained independent respiratory function, and 10% became dependent on mechanical ventilation, often indefinitely.^1,2,6

Today, many ventilator patients survive with good quality of life,⁴ even though ~10% of all ICU patients become ventilator-dependent for more than 21 days.^7,8 Usually, only those with neuromuscular disease cannot regain independent functioning.⁷

The Basics

Two types of mechanical ventilation are used: positive pressure and negative pressure. Positive pressure ventilation ("mouth-to-mouth resuscitation") helps patients overcome inspiratory resistance, opens alveoli and improves gas exchange, and helps patients inspire.

Negative pressure ventilation is the opposite ("an iron lung"), expanding the chest and causing inspiration using negative air pressure (a vacuum) around the chest. When the negative pressure is released, the chest collapses, and expiration occurs.^1,9

Invasive techniques?nasotracheal, orotracheal, and tracheostomy tubes? are the cornerstone of today's treatment for respiratory failure. Attached mechanical ventilation is considerably smaller than the iron lung and is often portable. Engineers have created alarm systems that signal potential problems early, although frequent beeping may create unnecessary anxiety for patients and families. Unfortunately, intubation interferes with mucociliary clearance and compromises the natural barrier between the oropharynx and the trachea? leading to a host of problems, the most serious being bacterial infection. Noninvasive techniques include various external devices such as tight-fitting face masks connected to ventilators.

Nasotracheal or orotracheal tubes are a first-line intervention. Airway and throat obstruction, however, make eating and speaking impossible and make intravenous (IV) or nasogastric (NG) feedings necessary.

If patients remain hospitalized for 10 days to 2 weeks, clinicians favor tracheostomy for long-term airway access (Table 1). Considered a last-resort intervention in the past, tracheostomies done before day 10 of ventilation have been shown to decrease ICU and hospital length of stay, as well as ventilation duration. The ability to eat provides a better nutrient source than total parenteral nutrition or NG feeding.^10,11

Ventilator Bundles

Comprehensive care includes frequent suctioning to prevent aspiration,¹² mental health care, recreational therapy, and family counseling. Clinicians must concurrently identify and correct the underlying causes of respiratory failure.³ Having a patient remain on a ventilator for more than 1 day increases the risk of ventilator-associated pneumonia (VAP), gastrointestinal (GI) bleeding, and altered glucose metabolism.^13-17

To ensure impeccable care, many ICUs and ventilator units use Joint Commission on the Accreditation of Healthcare Organizations-endorsed "ventilator bundles"?a set of performance improvement measures more comprehensive than any isolated measure.^12,18,19 Five measures, detailed here, can reduce morbidity and mortality significantly.¹⁸

Elevation of the Head of the Bed

With VAP's cumulative incidence of 1% to 3% per day, translating to its occurrence in up to 30% of ventilator-dependent patients, any measure that helps must be implemented. VAP occurring early in the patient's stay is usually antibiotic- sensitive. Late VAP is often nosocomial and antibiotic-resistant.²⁰

Elevating the head of the bed 30? to 45? is inexpensive and easy and can prevent VAP.²⁰ Regardless, it is physically impossible to elevate some older ICU beds 30?; this is a barrier. If the angle of elevation is uncertain, the physical therapist often has a goniometer (an instrument for measuring angles)¹⁸ and can measure the angle of semirecumbency.

Peptic Ulcer Disease Prophylaxis

The risk of upper GI bleeding skyrockets after 24 hours of mechanical ventilation. Almost 50% of patients who develop a bleed die.¹⁵ Although cimetidine is the only drug FDA-approved for upper GI bleeding prevention in critically ill patients, any acid-suppressant therapy? a histamine² receptor antagonist (H₂RA) or a proton pump inhibitor (PPI)?could be expected to work.¹⁸ The target is keeping gastric pH in the basic range (above 4).²⁰ Initially, these drugs are given by the IV route (if available), but oral forms are more cost-effective when the patient's IV is discontinued.^19,20 Antacids and H₂RAs work more quickly than PPIs, but PPIs suppress acid longer.²¹

Although a large, well-designed study proved this theory false,²² some clinicians contend that acid-suppressant therapy increases the gastric pathogenic organism population, and consequently VAP incidence. These clinicians prefer sucralfate.

Deep Vein Thrombosis Prophylaxis

Critical illness, immobilization, and mechanical ventilation increase the risk for venous thromboembolism. Thromboprophylaxis is necessary. Heparin, unfractionated heparin, warfarin, thromboembolic disease hose, and sequential compression devices all reduce risk.¹⁶

Daily Sedation Vacations and Spontaneous Breathing Trials (SBTs)

Clinicians differ in the speed with which they start SBTs. If the underlying causes are reversed, patients are adequately oxygenated, hemodynamic stability is present (no ischemia or hypotension), and patients can inspire, they should be able to discontinue ventilation.³

Tangential issues, however, complicate weaning. Patient fear or anxiety, inadequate strength, or drowsiness and disorientation can interfere with a weaning plan. Encouraging ambulation and keeping the environment stimulating are essential. Patients who transition from tracheostomies to nasal masks often find the mask cumbersome and disturbing. Allowing patients to wear the mask for increasing periods of time with ventilation may desensitize them.⁷

Once patients breathe spontaneously for 30 minutes to 2 hours, clinicians can consider permanent ventilation discontinuation. If, after 3 months, SBTs fail, patients are usually permanently ventilator- dependent.³

Intensive Insulin Therapy to Decrease Infection Rates

Hypermetabolism and hyperdynamic cardiovascular states are normal systemic responses to injury, infection, or stress. Increased oxygen consumption, hyperglycemia, hyperlactinemia, and high protein catabolism often follow.^23,24 Patients may experience hyperglycemia despite elevated insulin concentrations. Monitoring aggressively and initiating insulin can prevent complications and clinical diabetes.²⁴

Redundancy from Pharmacy

Hospital pharmacists should know whether their facilities employ bundles and be familiar with their content. Pharmacists also can translate bundles into standing orders, measurements, and feedback loops. Redundancy (eg, staff members checking behind other staff members) is important so that simple measures are not overlooked. Educating patients'families also helps.¹⁸

Final Thought

Several core elements drive optimal ventilator care (Table 2). Psychological factors should not be minimized. Because they potentially imperil SBTs, pharmacists should work with physicians to identify suitable pharmacotherapy for depression or anxiety.³

Ms. Wick is a senior clinical research pharmacist at the National Cancer Institute, National Institutes of Health, Bethesda, Md. Dr. Zanni is a health-systems consultant and a psychologist based in Alexandria,Va. The views expressed are those of the authors and not those of any government agency.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Stahl, Pharmacy Times, 241 Forsgate Drive, Jamesburg, NJ 08831; or send an e-mail request to: astahl@ascendmedia.com.