Outcomes of Patients Admitted to a Chronic Ventilator-Dependent Unit in an Acute-Care Hospital
DOUGLAS R. GRACEY, M.D., ROBERT W. VIGGIANO, M.D., Division of Thoracic Diseases and Internal Medicine and Critical Care Service; JAMES M. NAESSENS, M.P.H., Section ofBiostatistics; ROLF D. HUBMAYR, M.D., Division of Thoracic Diseases and Internal Medicine and Critical Care Service; MARC D. SILVERSTEIN, M.D., Division ofArea Medicine and Section of Clinical Epidemiology; GARY E. KOENIG, B.A., R.N., and the Nursing and Respiratory Therapy Staffs, Chronic Ventilator-Dependent Unit, Saint Marys Hospital
The outcomes in 61 patients admitted to a chronic ventilator-dependent unit (CVDU) at Saint Marys Hospital in Rochester, Minnesota, during an 18-month period are summarized. This unit was designed for patients who could not be weaned from mechanical ventilators after repeated attempts. Most patients had been ventilator dependent for more than 21 days, but some patients were admitted to the CVDU after briefer periods if special circumstances suggested that weaning from mechanical ventilation would be difficult. The unit was organized to provide a multidisciplinary approach to the general medical and respiratory management of these patients, including a physiologic evaluation of the respiratory system to determine the actual cause of ventilator dependence and complete medical, nursing, and psychosocial assessments to help adopt a plan of care and weaning from the ventilator. Of the numerous causes for ventilator dependence in this study group, chronic obstructive pulmonary disease was the most frequent underlying diagnosis. Of the 61 patients admitted to the CVDU, 58 survived, and 53 were liberated from the mechanical ventilator. Ultimately, 35 patients were dismissed directly home from the CVDU. Five of these patients required nocturnal mechanical ventilation. An additional eight patients were dismissed home after rehabilitation. After being weaned from mechanical ventilation, 11 patients were eventually transferred to nursing homes, and 3 additional patients were transferred to a local hospital or physical medicine unit. One patient remains in the CVDU. Thus, the CVDU has successfully liberated patients from ventilator dependence. In addition, because of a decreased need for nursing care, the unit has been cost-effective.
On Jan. 2, 1990, a chronic ventilator-dependent unit (CVDU) at Saint Marys Hospital in Rochester, Minnesota, was opened for patients who could not be liberated from mechanical ventilation after repeated attempts at weaning or who had a severe underlying pulmonary disease process that, after two unsuccessful attempts at weaning, made liberation from the ventilator highly unlikely. No ~imilar unit had
Address reprint requests to Dr. D. R. Gracey, Division of Thoracic Diseases, Mayo Clinic, Rochester, MN 55905. Mayo Clin Proc 67:131-136,1992
previously existed at our institution. All prolonged ventilator-dependent patients had previously received care in intensive-care units. This six-bed unit was planned to offer an organized, multidisciplinary approach to management of ventilatordependent patients. The approach includes a complete physiologic, medical, nursing, and psychosocial assessment of patients to determine the reasons for ventilator dependence. On the basis of this evaluation, we established a weaning program or a program for home or alternate site care. The comparative cost of care and reimbursement for
131
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CHRONIC VENTILATOR-DEPENDENT UNIT
these patients favors the use of the CVDU over the intensivecare units. This report details our first 18 months of experience with this CVDU.
PATIENTS AND METHODS Between Jan. 2, 1990, and June 30, 1991, 61 patients were admitted to the CVDU at our institution. The criteria for admission were as follows: stable medical condition, absence of the need for electrocardiographic monitoring, previous tracheostomy, and rehabilitation potential. On admission to the CVDU, patients underwent assessment of the function of the respiratory system, including measurements of maximal inspiratory and expiratory airway pressure, vital capacity, alveolar-arterial oxygen gradient, and ratio of dead space to tidal volume and determination of the mechanics of the respiratory system by using an interrupter technique. 1 In selected patients, diaphragmatic strength and function were measured. These studies included measurements of transdiaphragmatic pressure during voluntary contractions and during twitch stimulation with electromyography. On the basis of this evaluation, a plan for weaning from mechanical ventilation was developed and implemented. Each patient was examined by a physician from the Department of Physical Medicine and Rehabilitation, and a plan for rehabilitation was established. The program included passive range-of-motion exercises, weight and stretch therapy, and tilt table to standing programs. Ambulatiori with use of a pressure-regulated ventilator progressing to exercising in the supervised facilities in the Department of Physical Medicine and Rehabilitation was the goal, depending on individual patient ability. Patients also underwent assessment by an occupational therapist, with particular emphasis on difficulties with swallowing and retraining for swallowing. Nutritional problems were evaluated and addressed by the nutrition service. At the time of admission, most patients were receiving intravenous or enteric tube feedings in various stages of advancement to an enteral nutrition program. As soon as possible, catheters, central venous catheters used for parenteral nutrition, urinary catheters, and, when possible, feeding tubes were removed. Although many patients had dysphagia when a tracheostomy tube was in place, most patients who had no underlying neurologic deficit were able to advance to full oral diets. The nurses in the CVDU have special knowledge and skills and are critical to the management of these complicated long-term ventilator-dependent patients. The success of the unit depends on the preadmission and ongoing evaluations of the patients' general medical status, which were conducted by the nurses. When appropriate, psychosocial
Mayo Clin Proc, February 1992, Vol 67
evaluation was performed by the Department of Psychiatry and Psychology. For the first 36 patients admitted to the CVDU in 1990, reimbursement and cost data were also evaluated.
RESULTS Patient Demographics and Ventilator History.-Of the 61 ventilator-dependent patients admitted to the CVDU, 31 were women and 30 were men. The age range of the overall group was 24 to 89 years. The ages of the male patients were similar to the ages ofthe female patients (Table 1). The 61 patients had been in the hospital a mean of 38 days (range, 7 to 159 days) before admission to the CVDU and were in the CVDU a mean of an additional 33 days (range, 14 to 90 days). The patient with the longest hospital stay and the longest history of ventilator dependence had failure of multiple organs (heart, lung, kidney, and liver) after a cardiac operation and died 2 weeks after transfer to the CVDD. Before admission to the CVDU, the 61 patients had been ventilator dependent for a mean of 34 days (range, 7 to 159 days); in the CVDU, they were mechanically ventilated for a mean of 16 days (range, 2 to 56 days). Thus, the total duration of mechanical ventilation was a mean of 50 days (range, 16 to 181 days). Total days of mechanical ventilation and hospitalization were similar for men and women. Cause of Respiratory Failure and Ventilator Dependence.-A precise definition of chronic ventilator dependence in terms of duration has not been established in the literature. The definition established by the Health Care Financing Administration for the Chronic Ventilator-Dependent Unit Demonstration Project is dependence on a ventilator for more than 6 hours/day for more than 21 days. In our series, most patients had been ventilator dependent for more than 21 days, but a few were admitted to the CVDU after shorter periods of mechanical ventilation when special circumstances suggested that weaning would be difficult. Clearly, the term "ventilator dependence" reflects the inability to maintain adequate gas exchange without mechanical ventilation. The major causes of ventilator dependence in the 40 surgical and 21 medical patients are shown in Table 2. In our series of patients, the major cause of postoperative respiratory failure was acute deterioration of chronic obstructive pulmonary disease (23 patients). In many patients, this condition was diagnosed after a major emergency operation. Testing of respiratory mechanics by the interrupter technique disclosed unsuspected obstruction of airways in a substantial number of patients. Other postoperative patients who had been treated with intravenously administered aminophylline and inhaled bronchodilating agents for presumed chronic obstructive pulmonary disease were found to
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CHRONIC VENTILATOR-DEPENDENT UNIT
Table I.-Age, Gender, and Resource UtilizationData for 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990,Through June 30, 1991)* Factor Age (yr) Women (N = 31) Men (N = 30) Total Ventilator days (no.) Pre-CVDU CVDU Total Hospital days(no.) Pre-CVDU CVDU Total
Mean±SD
Range
68 ± 14 69 ± 11 68± 13
24-89 28-85 24-89
34±24 16± 12 50±29
7-159 2-56 16-181
38 ± 25 33 ± 19 71 ±34
7-159 14-90 21-195
*CVDU = chronic ventilator-dependent unit.
have normal recoil pressure-flow relationships when studied in the CvDU. In 10 patients, neuromuscular respiratory disease was the primary reason for respiratory failure, and an additional 8 patients had restrictive lung disease. The seven patients with postoperative respiratory failure were, in general, malnourished because of a prolonged catabolic or hypennetabolic state despite nutritional support, deconditioned from prolonged bed rest, or suffering from benzodiazepine withdrawal. Eight other patients had either acute lung injury or medical causes for respiratory failure. Many patients had multiple reasons for impaired respiratory function. For example, one patient had severe chronic obstructive pulmonary disease and adult respiratory distress syndrome, complicating progressive motor neuron disease that was unsuspected preoperatively. Another patient, a 28year-old man with Ehlers-Danlos syndrome and osteogenesis imperfecta, became ventilator dependent after undergoing replacement of the mitral and aortic valves, and he had severe restrictive lung disease (vital capacity, 600 ml). Source ofAdmission and Outcome.-The 61 patients in the CvDU were admitted from 10 services (Table 3). The major sources of admission were the medical intensive-care unit (19 patients) and the thoracic (12 patients) and vascular (9 patients) surgical areas. Ofthe 61 patients admitted, 58 survived and 3 died in the CVDU. One patient with failure of multiple organs refused dialysis and died while being mechanically ventilated. One patient with recurrent lung cancer and severe chronic obstructive pulmonary disease died of gram-negative pneumonia and sepsis. He had been free of mechanical ventilation for more than 6 weeks before his death and refused reintubation. A patient with motor neuron disease who had been free
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Table 2.-Major Underlying DiagnosesContributing to Ventilator Dependence in 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990,Through June 30, 1991)
Majordiagnosis COPD* Neuromuscular disorder Restrictive lung disease Postoperative respiratory failure Acute lung injury Heart disease Other
No. of patients Total Surgical Medical (N =40) (N = 21) (N = 61) 23 3 3
5 7 5
28
7 4 0 0
0
7 5 2 1
1 2 1
10
8
*COPD = chronic obstructive pulmonary disease.
of mechanical ventilation for 2 weeks died in the CVDU when he refused to have mechanical ventilation reinstituted for acute deterioration of his respiratory status after anesthesia for a surgical gastrostomy. Of the 58 survivors, 53 were liberated from mechanical ventilation (Table 4). Five patients who were dismissed directly home used nocturnal mechanical ventilation (for neuromuscular disease, severe kyphoscoliosis, or central sleep apnea). -, The disposition of the 61 patients is shown in Table 5. Most patients returned home. Of the 11 patients who were eventually dismissed to a chronic-care facility, some subsequently returned to their homes or are expected to do so. Nutritional assessment invariably revealed evidence of a poor nutritional status. Most patients admitted to the CVDU had hypoalbuminemia (mean serum albumin, 2.77 ± 0.60 mg/dl; range, 1.7 to 4.4 mg/dl). At the time of dismissal, the mean serum albumin was 3.12 ± 0.44 mg/dl (range, 2.5 to 4.2 mg/dl). The hypoalbuminemia was attributed to catabolic status and decreased synthesis, which were associated with severe illness. Reimbursement and Cost Data.-The daily cost of care and reimbursement were calculated for the days in the intensive-care unit before admission to the CVDU and for the CVDU. The ratio of nurses to patients in the CVDU averaged 1:2.5; this ratio varied from 1:1 to 1:2 in the intensivecare units. Although both Medicare and non-Medicare patients were represented, Medicare was the major third-party payer. The net difference between cost and reimbursement in a comparison of the intensive-care units and the CVDU was $603.95 per day in favor of the CVDU. The daily mean difference between cost and reimbursement in the intensive-
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CHRONIC VENTILATOR-DEPENDENT UNIT
Table 3.-Sources of Admission for 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990, Through June 30, 1991)
Admitting source
No. of patients
Medical intensive-care unit Thoracic surgery Vascular surgery Emergency department surgical service Cardiovascular surgery Gynecologic surgery Orthopedic surgery Renal transplant surgical service Neurosurgery Cardiology Total
19 12 9 7 7 2 2 1 1
1 61
care units was a loss of $299.06, whereas the daily mean difference in the CVDU was a gain of $304.89. DISCUSSION Little information has been published about hospital units dedicated to the care of ventilator-dependent patients.r" Indihar' analyzed a l O-year experience with 171 ventilatordependent patients (92 women and 79 men) admitted to such a unit. In that patient population, numerous disease processes led to ventilator dependence, but 67.1% of the patients had chronic obstructive pulmonary disease. The percentage of patients weaned from the mechanical ventilator varied by diagnostic category and ranged from 17.4% of patients with diseases of the brain and spinal cord to 100% of those with cancer. Overall, 34% of the 171 patients were weaned from the ventilator, one-third died, and the other one-third remained ventilator dependent. Of the ventilatordependent patients admitted, 21.7% were dismissed home and another 13% were dismissed to skilled nursing facilities. To our knowledge, this is the largest published series of such patients in a special prolonged ventilatory assistance unit. In comparison, 61 ventilator-dependent patients were admitted to ourCVDU during an 18-month period. Of the 61 patients, 43 (71%) were dismissed directly home or went home after participation in rehabilitation to improve their skills with activities of daily living. Eleven of the patients (18%) were transferred to nursing homes, some of whom had originally been admitted to the hospital from nursing homes. The success with which our patients were weaned from mechanical ventilation was relatively better than the result in Indihar's series," Almost 90% of our 61 patients were successfully liberated from the ventilator. One patient died of failure of multiple organs during mechanical ventilation, and five others who were dismissed home used nocturnal ventila-
tion to minimize retention of carbon dioxide and hypoxia. Comparison of these two series is inappropriate, however, because the patient population in the report by Indihar had been mechanically ventilated for much longer periods before admission to the CVDU than had our patients. Cordasco and associates' recently published their experience with 99 stable long-term ventilator-dependent patients who received care in a non-intensive-care unit setting of a tertiary-care hospital during a 92-month period. The patients were classified as rehabilitative (50 patients) or custodial (49 patients). All but 1 of25 nonsurvivors were from the custodial group. Of the 25 patients weaned from the ventilator, 24 were from the rehabilitative group. Ventilator support at home was required by 30 patients-20 in the rehabilitative group who used partial mechanical ventilation and lOin the custodial group who required full-time ventilator support. Of the 74 survivors, 25 were completely weaned from mechanical ventilation, 24 of whom were from the rehabilitative group. Make and co-workers" emphasized the importance of a multidisciplinary approach for rehabilitation of ventilatordependent patients with lung diseases. Theydescribed five phases in the management of such patients: stabilization; evaluation; planning for rehabilitation, including motivation by allowing speech and mobility; rehabilitation training; and planning for dismissal. Our program, although not patterned after that of Make and colleagues, uses a similar approach. After initial physiologic, nutritional, and medical assessments, we approached the management and weaning of the patients from mechanical ventilation in the same multidisciplinary manner. In addition to allowing ambulation of our patients as soon as was physically possible with use of a pressure-regulated ventilator, we inserted either an Argyll or a Bivona tracheostomy tube in the patients early in their course in the CVDU. Both of these tracheostomy tubes are equipped with cuffs that, when deflated, collapse tightly on the tube and allow the patient to breathe around the tube and talk when the tube is corked. Not all patients tolerate such efforts early in their course in the CVDU; however, when they do, mental well-being and motivation are considerably Table 4.-0utcome of Ventilatory Failure in 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990, Through June 30, 1991)
Outcome No mechanical ventilation Homemechanical ventilation Homeoxygen Died in hospital Total
Patients % No. 40 5 13 3 61
66 8 21 5 100
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CHRONIC VENTILATOR-DEPENDENT UNIT
Table 5.-Dismissal Location of 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2,1990, Through June 30,1991) Patients Dismissal location Home Dismissed directly Rehabilitation then home Another hospital or rehabilitation unit then home Chronic-care facility Dismissed directly A medical floor of our hospital then chronic-care facility Remains in unit Died in hospital Total
No.
%
35 8
57 13
3
5
9
15
2 1 3 61
3 2 5 100
enhanced by being able to talk and communicate, even if only briefly. Our program for liberating these patients from the mechanical ventilator has been aided immeasurably by a detailed assessment of pulmonary and respiratory pump function.!? This assessment often revealed unsuspected disease of the airways, dynamic hyperinflation, muscle weakness, or cardiac limitations to weaning. As noted previously, many patients who were ventilator dependent had not undergone pulmonary function testing before the acute medical or surgical illness that prompted their hospitalization. The ability to measure pulmonary mechanics of ventilator-dependent patients assisted us in diagnosing the cause of ventilator dependence and planning the patient's weaning program. During the first 18 months of operation of the CVDU, we frequently observed two pharmacologic problems that aggravated the medical condition of patients and seemed to prolong ventilator dependence in the intensive-care units. The first problem was the inappropriate use of midazolam to alleviate agitation. A short-acting benzodiazepine, midazolam is administered in the intensive-care unit to treat agitation and is then repeatedly given for acute exacerbations of the agitated state. Patients who require minimal ventilator support frequently need complete mechanical ventilation after administration of midazolam; a pattern of rapid fluctuation from full support to minimal support may follow for many days. These patients respond promptly to a tapering schedule of chlordiazepoxide hydrochloride. Another pharmacologic problem frequently noted in these patients was osmotic diarrhea due to sorbitol (a poorly absorbed sweetening agent) contained in elixir medications given through the feeding tube. One commonly used theophyllineelixir, for example, contains 32 g of sorbitol in the standard daily dose. Other elixirs such as acetaminophen
135
also contain sorbitol. The problem with diarrhea can be avoided by suspending drugs in water to administer them through feeding tubes. 10. 11 patients who required prolonged mechanical ventilation, Morganroth and associates" found that spontaneous ventilatory measurements were not useful for judging the ability to tolerate liberation from mechanical ventilation. They found that these measurements remained unchanged from the period of unsuccessful weaning to the period of progressive weaning from the ventilator. Improvement in such factors as heart rate, blood pressure, arrhythmias, quantity of secretions, level of consciousness, and medication requirements did affect weaning. Although we agree with these findings in general, some of our patients had notable improvement in their measurable physiologic variables, which ultimately allowed weaning from the ventilator. For example, several patients with large alveolar-arterial oxygen gradients or large measured dead space in association with reduced lung compliance had progressive improvement in their physiologic defects, which allowed them to be liberated from mechanical ventilation. In addition, patients who had been in prolonged catabolic status and subjected to prolonged bed rest with total ventilator support had considerable improvement in the strength of their respiratory muscles, as documented by measurements of maximal inspiratory and expiratory airway pressure. Spicher and White? reported a survival rate of 39.2% at dismissal among 250 patients who had been mechanically ventilated for a minimum of 10 days. At 1 year, 28.5% of these patients were alive, and survival was 22.5% at 2 years. Of the patients who survived and were dismissed from the hospital, 39.6% were institutionalized and 32.7% were homebound. Only 3% of survivors had no functional impairment. Therefore, these investigators concluded that prolonged mechanical ventilation is associated with limited survival and poor functional status in those who survive. A study of 104 patients who received mechanical ventilation for more than 29 days at our institution revealed substantially different results." Of the 104 patients, 57.6% survived and were dismissed from the hospital. The overall probability of surviving, including hospital mortality, after dismissal was 38.7%, 35.1%, and 32.6%, respectively, at 1, 2, and 3 years. Most survivors were functioning normally. The differences in mortality between these two studies could reflect the 39% incidence of postoperative respiratory failure in our series of 104 patients. We have not analyzed the longterm survival after hospitalization in the current series of 61 patients In the CVDU because the unit has been in operation for only 18 months. The mean daily cost per patient in the CVDU is substantially less than the daily cost of care in the intensive-care unit because of a decreased need for nursing care. We believe
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CHRONIC VENTILATOR-DEPENDENT UNIT
that the total intensive-care unit and hospital durations of stay were shorter for patients who were admitted to the CVDU than they would have been had the CVDU not been established. This difference is especially important from the perspective of acute-care hospitals, which have experienced limitations in reimbursement for care of ventilator-dependent patients and other critically ill patients.
CONCLUSION A multidisciplinary planned approach to liberating ventilator-dependent patients from mechanical ventilation in a
CVDU has proved highly successful. Most patients were weaned from the ventilator and dismissed home. In addition, the cost of care for long-term mechanical ventilation of patients in the CVDU is lower than the cost of management of such patients in the intensive-care unit. REFERENCES 1. Hubmayr RD, Gay PC, Tayyab M: Respiratory system mechanics in ventilated patients: techniques and indications. Mayo Clin Proc 62:358-368, 1987
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2.
Indihar FJ, Forsberg DP: Experience with a prolonged respiratory care unit. Chest 81:189-192, 1982 3. Indihar FJ, Walker NE: Experience with a prolonged respiratory care unit-revisited. Chest 86:616-620, 1984 4. Indihar FJ: A 1O-year report of patients in a prolonged respiratory care unit. Minn Med 74:23-27, April 1991 5. Cordasco EM Jr, Sivak ED, Perez-Trepichio A: Demographics of long-term ventilator-dependent patients outside the intensive care unit. Cleve Clin J Med 58:505-509, 1991 6. Make B, Gilmartin M, Brody JS, Snider GL: Rehabilitation of ventilator-dependent subjects with lung diseases: the concept and initial experience. Chest 86:358-365,1984 7. Gay PC, Rodarte JR, Tayyab M, Hubmayr RD: Evaluation of bronchodilator responsiveness in mechanically ventilated patients. Am Rev Respir Dis 136:880-885,1987 8. Morganroth ML, Morganroth JL, Nett LM, Petty TL: Criteria for weaning from prolonged mechanical ventilation. Arch Intern Med 144:1012-1016,1984 9. Spicher JE, White DP: Outcome and function following prolonged mechanical ventilation. Arch Intern Med 147:421-425,1987 10. Gracey DR, Naessens JM, Krishan I, Marsh HM: Hospital and post-hospital survival in patients mechanically ventilated for greater than 29 days. Chest 101:211-214, 1992
DOUGLAS R. GRACEY, M.D., ROBERT W. VIGGIANO, M.D., Division of Thoracic Diseases and Internal Medicine and Critical Care Service; JAMES M. NAESSENS, M.P.H., Section ofBiostatistics; ROLF D. HUBMAYR, M.D., Division of Thoracic Diseases and Internal Medicine and Critical Care Service; MARC D. SILVERSTEIN, M.D., Division ofArea Medicine and Section of Clinical Epidemiology; GARY E. KOENIG, B.A., R.N., and the Nursing and Respiratory Therapy Staffs, Chronic Ventilator-Dependent Unit, Saint Marys Hospital
The outcomes in 61 patients admitted to a chronic ventilator-dependent unit (CVDU) at Saint Marys Hospital in Rochester, Minnesota, during an 18-month period are summarized. This unit was designed for patients who could not be weaned from mechanical ventilators after repeated attempts. Most patients had been ventilator dependent for more than 21 days, but some patients were admitted to the CVDU after briefer periods if special circumstances suggested that weaning from mechanical ventilation would be difficult. The unit was organized to provide a multidisciplinary approach to the general medical and respiratory management of these patients, including a physiologic evaluation of the respiratory system to determine the actual cause of ventilator dependence and complete medical, nursing, and psychosocial assessments to help adopt a plan of care and weaning from the ventilator. Of the numerous causes for ventilator dependence in this study group, chronic obstructive pulmonary disease was the most frequent underlying diagnosis. Of the 61 patients admitted to the CVDU, 58 survived, and 53 were liberated from the mechanical ventilator. Ultimately, 35 patients were dismissed directly home from the CVDU. Five of these patients required nocturnal mechanical ventilation. An additional eight patients were dismissed home after rehabilitation. After being weaned from mechanical ventilation, 11 patients were eventually transferred to nursing homes, and 3 additional patients were transferred to a local hospital or physical medicine unit. One patient remains in the CVDU. Thus, the CVDU has successfully liberated patients from ventilator dependence. In addition, because of a decreased need for nursing care, the unit has been cost-effective.
On Jan. 2, 1990, a chronic ventilator-dependent unit (CVDU) at Saint Marys Hospital in Rochester, Minnesota, was opened for patients who could not be liberated from mechanical ventilation after repeated attempts at weaning or who had a severe underlying pulmonary disease process that, after two unsuccessful attempts at weaning, made liberation from the ventilator highly unlikely. No ~imilar unit had
Address reprint requests to Dr. D. R. Gracey, Division of Thoracic Diseases, Mayo Clinic, Rochester, MN 55905. Mayo Clin Proc 67:131-136,1992
previously existed at our institution. All prolonged ventilator-dependent patients had previously received care in intensive-care units. This six-bed unit was planned to offer an organized, multidisciplinary approach to management of ventilatordependent patients. The approach includes a complete physiologic, medical, nursing, and psychosocial assessment of patients to determine the reasons for ventilator dependence. On the basis of this evaluation, we established a weaning program or a program for home or alternate site care. The comparative cost of care and reimbursement for
131
132
CHRONIC VENTILATOR-DEPENDENT UNIT
these patients favors the use of the CVDU over the intensivecare units. This report details our first 18 months of experience with this CVDU.
PATIENTS AND METHODS Between Jan. 2, 1990, and June 30, 1991, 61 patients were admitted to the CVDU at our institution. The criteria for admission were as follows: stable medical condition, absence of the need for electrocardiographic monitoring, previous tracheostomy, and rehabilitation potential. On admission to the CVDU, patients underwent assessment of the function of the respiratory system, including measurements of maximal inspiratory and expiratory airway pressure, vital capacity, alveolar-arterial oxygen gradient, and ratio of dead space to tidal volume and determination of the mechanics of the respiratory system by using an interrupter technique. 1 In selected patients, diaphragmatic strength and function were measured. These studies included measurements of transdiaphragmatic pressure during voluntary contractions and during twitch stimulation with electromyography. On the basis of this evaluation, a plan for weaning from mechanical ventilation was developed and implemented. Each patient was examined by a physician from the Department of Physical Medicine and Rehabilitation, and a plan for rehabilitation was established. The program included passive range-of-motion exercises, weight and stretch therapy, and tilt table to standing programs. Ambulatiori with use of a pressure-regulated ventilator progressing to exercising in the supervised facilities in the Department of Physical Medicine and Rehabilitation was the goal, depending on individual patient ability. Patients also underwent assessment by an occupational therapist, with particular emphasis on difficulties with swallowing and retraining for swallowing. Nutritional problems were evaluated and addressed by the nutrition service. At the time of admission, most patients were receiving intravenous or enteric tube feedings in various stages of advancement to an enteral nutrition program. As soon as possible, catheters, central venous catheters used for parenteral nutrition, urinary catheters, and, when possible, feeding tubes were removed. Although many patients had dysphagia when a tracheostomy tube was in place, most patients who had no underlying neurologic deficit were able to advance to full oral diets. The nurses in the CVDU have special knowledge and skills and are critical to the management of these complicated long-term ventilator-dependent patients. The success of the unit depends on the preadmission and ongoing evaluations of the patients' general medical status, which were conducted by the nurses. When appropriate, psychosocial
Mayo Clin Proc, February 1992, Vol 67
evaluation was performed by the Department of Psychiatry and Psychology. For the first 36 patients admitted to the CVDU in 1990, reimbursement and cost data were also evaluated.
RESULTS Patient Demographics and Ventilator History.-Of the 61 ventilator-dependent patients admitted to the CVDU, 31 were women and 30 were men. The age range of the overall group was 24 to 89 years. The ages of the male patients were similar to the ages ofthe female patients (Table 1). The 61 patients had been in the hospital a mean of 38 days (range, 7 to 159 days) before admission to the CVDU and were in the CVDU a mean of an additional 33 days (range, 14 to 90 days). The patient with the longest hospital stay and the longest history of ventilator dependence had failure of multiple organs (heart, lung, kidney, and liver) after a cardiac operation and died 2 weeks after transfer to the CVDD. Before admission to the CVDU, the 61 patients had been ventilator dependent for a mean of 34 days (range, 7 to 159 days); in the CVDU, they were mechanically ventilated for a mean of 16 days (range, 2 to 56 days). Thus, the total duration of mechanical ventilation was a mean of 50 days (range, 16 to 181 days). Total days of mechanical ventilation and hospitalization were similar for men and women. Cause of Respiratory Failure and Ventilator Dependence.-A precise definition of chronic ventilator dependence in terms of duration has not been established in the literature. The definition established by the Health Care Financing Administration for the Chronic Ventilator-Dependent Unit Demonstration Project is dependence on a ventilator for more than 6 hours/day for more than 21 days. In our series, most patients had been ventilator dependent for more than 21 days, but a few were admitted to the CVDU after shorter periods of mechanical ventilation when special circumstances suggested that weaning would be difficult. Clearly, the term "ventilator dependence" reflects the inability to maintain adequate gas exchange without mechanical ventilation. The major causes of ventilator dependence in the 40 surgical and 21 medical patients are shown in Table 2. In our series of patients, the major cause of postoperative respiratory failure was acute deterioration of chronic obstructive pulmonary disease (23 patients). In many patients, this condition was diagnosed after a major emergency operation. Testing of respiratory mechanics by the interrupter technique disclosed unsuspected obstruction of airways in a substantial number of patients. Other postoperative patients who had been treated with intravenously administered aminophylline and inhaled bronchodilating agents for presumed chronic obstructive pulmonary disease were found to
Mayo Clin Proc, February 1992, Vol 67
CHRONIC VENTILATOR-DEPENDENT UNIT
Table I.-Age, Gender, and Resource UtilizationData for 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990,Through June 30, 1991)* Factor Age (yr) Women (N = 31) Men (N = 30) Total Ventilator days (no.) Pre-CVDU CVDU Total Hospital days(no.) Pre-CVDU CVDU Total
Mean±SD
Range
68 ± 14 69 ± 11 68± 13
24-89 28-85 24-89
34±24 16± 12 50±29
7-159 2-56 16-181
38 ± 25 33 ± 19 71 ±34
7-159 14-90 21-195
*CVDU = chronic ventilator-dependent unit.
have normal recoil pressure-flow relationships when studied in the CvDU. In 10 patients, neuromuscular respiratory disease was the primary reason for respiratory failure, and an additional 8 patients had restrictive lung disease. The seven patients with postoperative respiratory failure were, in general, malnourished because of a prolonged catabolic or hypennetabolic state despite nutritional support, deconditioned from prolonged bed rest, or suffering from benzodiazepine withdrawal. Eight other patients had either acute lung injury or medical causes for respiratory failure. Many patients had multiple reasons for impaired respiratory function. For example, one patient had severe chronic obstructive pulmonary disease and adult respiratory distress syndrome, complicating progressive motor neuron disease that was unsuspected preoperatively. Another patient, a 28year-old man with Ehlers-Danlos syndrome and osteogenesis imperfecta, became ventilator dependent after undergoing replacement of the mitral and aortic valves, and he had severe restrictive lung disease (vital capacity, 600 ml). Source ofAdmission and Outcome.-The 61 patients in the CvDU were admitted from 10 services (Table 3). The major sources of admission were the medical intensive-care unit (19 patients) and the thoracic (12 patients) and vascular (9 patients) surgical areas. Ofthe 61 patients admitted, 58 survived and 3 died in the CVDU. One patient with failure of multiple organs refused dialysis and died while being mechanically ventilated. One patient with recurrent lung cancer and severe chronic obstructive pulmonary disease died of gram-negative pneumonia and sepsis. He had been free of mechanical ventilation for more than 6 weeks before his death and refused reintubation. A patient with motor neuron disease who had been free
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Table 2.-Major Underlying DiagnosesContributing to Ventilator Dependence in 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990,Through June 30, 1991)
Majordiagnosis COPD* Neuromuscular disorder Restrictive lung disease Postoperative respiratory failure Acute lung injury Heart disease Other
No. of patients Total Surgical Medical (N =40) (N = 21) (N = 61) 23 3 3
5 7 5
28
7 4 0 0
0
7 5 2 1
1 2 1
10
8
*COPD = chronic obstructive pulmonary disease.
of mechanical ventilation for 2 weeks died in the CVDU when he refused to have mechanical ventilation reinstituted for acute deterioration of his respiratory status after anesthesia for a surgical gastrostomy. Of the 58 survivors, 53 were liberated from mechanical ventilation (Table 4). Five patients who were dismissed directly home used nocturnal mechanical ventilation (for neuromuscular disease, severe kyphoscoliosis, or central sleep apnea). -, The disposition of the 61 patients is shown in Table 5. Most patients returned home. Of the 11 patients who were eventually dismissed to a chronic-care facility, some subsequently returned to their homes or are expected to do so. Nutritional assessment invariably revealed evidence of a poor nutritional status. Most patients admitted to the CVDU had hypoalbuminemia (mean serum albumin, 2.77 ± 0.60 mg/dl; range, 1.7 to 4.4 mg/dl). At the time of dismissal, the mean serum albumin was 3.12 ± 0.44 mg/dl (range, 2.5 to 4.2 mg/dl). The hypoalbuminemia was attributed to catabolic status and decreased synthesis, which were associated with severe illness. Reimbursement and Cost Data.-The daily cost of care and reimbursement were calculated for the days in the intensive-care unit before admission to the CVDU and for the CVDU. The ratio of nurses to patients in the CVDU averaged 1:2.5; this ratio varied from 1:1 to 1:2 in the intensivecare units. Although both Medicare and non-Medicare patients were represented, Medicare was the major third-party payer. The net difference between cost and reimbursement in a comparison of the intensive-care units and the CVDU was $603.95 per day in favor of the CVDU. The daily mean difference between cost and reimbursement in the intensive-
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Table 3.-Sources of Admission for 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990, Through June 30, 1991)
Admitting source
No. of patients
Medical intensive-care unit Thoracic surgery Vascular surgery Emergency department surgical service Cardiovascular surgery Gynecologic surgery Orthopedic surgery Renal transplant surgical service Neurosurgery Cardiology Total
19 12 9 7 7 2 2 1 1
1 61
care units was a loss of $299.06, whereas the daily mean difference in the CVDU was a gain of $304.89. DISCUSSION Little information has been published about hospital units dedicated to the care of ventilator-dependent patients.r" Indihar' analyzed a l O-year experience with 171 ventilatordependent patients (92 women and 79 men) admitted to such a unit. In that patient population, numerous disease processes led to ventilator dependence, but 67.1% of the patients had chronic obstructive pulmonary disease. The percentage of patients weaned from the mechanical ventilator varied by diagnostic category and ranged from 17.4% of patients with diseases of the brain and spinal cord to 100% of those with cancer. Overall, 34% of the 171 patients were weaned from the ventilator, one-third died, and the other one-third remained ventilator dependent. Of the ventilatordependent patients admitted, 21.7% were dismissed home and another 13% were dismissed to skilled nursing facilities. To our knowledge, this is the largest published series of such patients in a special prolonged ventilatory assistance unit. In comparison, 61 ventilator-dependent patients were admitted to ourCVDU during an 18-month period. Of the 61 patients, 43 (71%) were dismissed directly home or went home after participation in rehabilitation to improve their skills with activities of daily living. Eleven of the patients (18%) were transferred to nursing homes, some of whom had originally been admitted to the hospital from nursing homes. The success with which our patients were weaned from mechanical ventilation was relatively better than the result in Indihar's series," Almost 90% of our 61 patients were successfully liberated from the ventilator. One patient died of failure of multiple organs during mechanical ventilation, and five others who were dismissed home used nocturnal ventila-
tion to minimize retention of carbon dioxide and hypoxia. Comparison of these two series is inappropriate, however, because the patient population in the report by Indihar had been mechanically ventilated for much longer periods before admission to the CVDU than had our patients. Cordasco and associates' recently published their experience with 99 stable long-term ventilator-dependent patients who received care in a non-intensive-care unit setting of a tertiary-care hospital during a 92-month period. The patients were classified as rehabilitative (50 patients) or custodial (49 patients). All but 1 of25 nonsurvivors were from the custodial group. Of the 25 patients weaned from the ventilator, 24 were from the rehabilitative group. Ventilator support at home was required by 30 patients-20 in the rehabilitative group who used partial mechanical ventilation and lOin the custodial group who required full-time ventilator support. Of the 74 survivors, 25 were completely weaned from mechanical ventilation, 24 of whom were from the rehabilitative group. Make and co-workers" emphasized the importance of a multidisciplinary approach for rehabilitation of ventilatordependent patients with lung diseases. Theydescribed five phases in the management of such patients: stabilization; evaluation; planning for rehabilitation, including motivation by allowing speech and mobility; rehabilitation training; and planning for dismissal. Our program, although not patterned after that of Make and colleagues, uses a similar approach. After initial physiologic, nutritional, and medical assessments, we approached the management and weaning of the patients from mechanical ventilation in the same multidisciplinary manner. In addition to allowing ambulation of our patients as soon as was physically possible with use of a pressure-regulated ventilator, we inserted either an Argyll or a Bivona tracheostomy tube in the patients early in their course in the CVDU. Both of these tracheostomy tubes are equipped with cuffs that, when deflated, collapse tightly on the tube and allow the patient to breathe around the tube and talk when the tube is corked. Not all patients tolerate such efforts early in their course in the CVDU; however, when they do, mental well-being and motivation are considerably Table 4.-0utcome of Ventilatory Failure in 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2, 1990, Through June 30, 1991)
Outcome No mechanical ventilation Homemechanical ventilation Homeoxygen Died in hospital Total
Patients % No. 40 5 13 3 61
66 8 21 5 100
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Table 5.-Dismissal Location of 61 Mayo Patients in the Chronic Ventilator-Dependent Unit (Jan. 2,1990, Through June 30,1991) Patients Dismissal location Home Dismissed directly Rehabilitation then home Another hospital or rehabilitation unit then home Chronic-care facility Dismissed directly A medical floor of our hospital then chronic-care facility Remains in unit Died in hospital Total
No.
%
35 8
57 13
3
5
9
15
2 1 3 61
3 2 5 100
enhanced by being able to talk and communicate, even if only briefly. Our program for liberating these patients from the mechanical ventilator has been aided immeasurably by a detailed assessment of pulmonary and respiratory pump function.!? This assessment often revealed unsuspected disease of the airways, dynamic hyperinflation, muscle weakness, or cardiac limitations to weaning. As noted previously, many patients who were ventilator dependent had not undergone pulmonary function testing before the acute medical or surgical illness that prompted their hospitalization. The ability to measure pulmonary mechanics of ventilator-dependent patients assisted us in diagnosing the cause of ventilator dependence and planning the patient's weaning program. During the first 18 months of operation of the CVDU, we frequently observed two pharmacologic problems that aggravated the medical condition of patients and seemed to prolong ventilator dependence in the intensive-care units. The first problem was the inappropriate use of midazolam to alleviate agitation. A short-acting benzodiazepine, midazolam is administered in the intensive-care unit to treat agitation and is then repeatedly given for acute exacerbations of the agitated state. Patients who require minimal ventilator support frequently need complete mechanical ventilation after administration of midazolam; a pattern of rapid fluctuation from full support to minimal support may follow for many days. These patients respond promptly to a tapering schedule of chlordiazepoxide hydrochloride. Another pharmacologic problem frequently noted in these patients was osmotic diarrhea due to sorbitol (a poorly absorbed sweetening agent) contained in elixir medications given through the feeding tube. One commonly used theophyllineelixir, for example, contains 32 g of sorbitol in the standard daily dose. Other elixirs such as acetaminophen
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also contain sorbitol. The problem with diarrhea can be avoided by suspending drugs in water to administer them through feeding tubes. 10. 11 patients who required prolonged mechanical ventilation, Morganroth and associates" found that spontaneous ventilatory measurements were not useful for judging the ability to tolerate liberation from mechanical ventilation. They found that these measurements remained unchanged from the period of unsuccessful weaning to the period of progressive weaning from the ventilator. Improvement in such factors as heart rate, blood pressure, arrhythmias, quantity of secretions, level of consciousness, and medication requirements did affect weaning. Although we agree with these findings in general, some of our patients had notable improvement in their measurable physiologic variables, which ultimately allowed weaning from the ventilator. For example, several patients with large alveolar-arterial oxygen gradients or large measured dead space in association with reduced lung compliance had progressive improvement in their physiologic defects, which allowed them to be liberated from mechanical ventilation. In addition, patients who had been in prolonged catabolic status and subjected to prolonged bed rest with total ventilator support had considerable improvement in the strength of their respiratory muscles, as documented by measurements of maximal inspiratory and expiratory airway pressure. Spicher and White? reported a survival rate of 39.2% at dismissal among 250 patients who had been mechanically ventilated for a minimum of 10 days. At 1 year, 28.5% of these patients were alive, and survival was 22.5% at 2 years. Of the patients who survived and were dismissed from the hospital, 39.6% were institutionalized and 32.7% were homebound. Only 3% of survivors had no functional impairment. Therefore, these investigators concluded that prolonged mechanical ventilation is associated with limited survival and poor functional status in those who survive. A study of 104 patients who received mechanical ventilation for more than 29 days at our institution revealed substantially different results." Of the 104 patients, 57.6% survived and were dismissed from the hospital. The overall probability of surviving, including hospital mortality, after dismissal was 38.7%, 35.1%, and 32.6%, respectively, at 1, 2, and 3 years. Most survivors were functioning normally. The differences in mortality between these two studies could reflect the 39% incidence of postoperative respiratory failure in our series of 104 patients. We have not analyzed the longterm survival after hospitalization in the current series of 61 patients In the CVDU because the unit has been in operation for only 18 months. The mean daily cost per patient in the CVDU is substantially less than the daily cost of care in the intensive-care unit because of a decreased need for nursing care. We believe
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that the total intensive-care unit and hospital durations of stay were shorter for patients who were admitted to the CVDU than they would have been had the CVDU not been established. This difference is especially important from the perspective of acute-care hospitals, which have experienced limitations in reimbursement for care of ventilator-dependent patients and other critically ill patients.
CONCLUSION A multidisciplinary planned approach to liberating ventilator-dependent patients from mechanical ventilation in a
CVDU has proved highly successful. Most patients were weaned from the ventilator and dismissed home. In addition, the cost of care for long-term mechanical ventilation of patients in the CVDU is lower than the cost of management of such patients in the intensive-care unit. REFERENCES 1. Hubmayr RD, Gay PC, Tayyab M: Respiratory system mechanics in ventilated patients: techniques and indications. Mayo Clin Proc 62:358-368, 1987
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2.
Indihar FJ, Forsberg DP: Experience with a prolonged respiratory care unit. Chest 81:189-192, 1982 3. Indihar FJ, Walker NE: Experience with a prolonged respiratory care unit-revisited. Chest 86:616-620, 1984 4. Indihar FJ: A 1O-year report of patients in a prolonged respiratory care unit. Minn Med 74:23-27, April 1991 5. Cordasco EM Jr, Sivak ED, Perez-Trepichio A: Demographics of long-term ventilator-dependent patients outside the intensive care unit. Cleve Clin J Med 58:505-509, 1991 6. Make B, Gilmartin M, Brody JS, Snider GL: Rehabilitation of ventilator-dependent subjects with lung diseases: the concept and initial experience. Chest 86:358-365,1984 7. Gay PC, Rodarte JR, Tayyab M, Hubmayr RD: Evaluation of bronchodilator responsiveness in mechanically ventilated patients. Am Rev Respir Dis 136:880-885,1987 8. Morganroth ML, Morganroth JL, Nett LM, Petty TL: Criteria for weaning from prolonged mechanical ventilation. Arch Intern Med 144:1012-1016,1984 9. Spicher JE, White DP: Outcome and function following prolonged mechanical ventilation. Arch Intern Med 147:421-425,1987 10. Gracey DR, Naessens JM, Krishan I, Marsh HM: Hospital and post-hospital survival in patients mechanically ventilated for greater than 29 days. Chest 101:211-214, 1992
