1603
the reliability of the arterial occlusion technique for estimation of the capillary pressure. We would point out, however, that systematic differences in the analysis of the postarterial occlusion technique tracings can lead to systematic error in the estimated capillary pressure, however small. Thus, it is important to define one best set of criteria to eliminate inconsistencies due to method of analysis. With continued contributions from different investigators, this hopefully will be accomplished.
TIMafHY H. SELF, PHARM.D.
Professor of Clinical Pharmacy Department of Clinical Pharmacy MARK J. RUMBAK, M.D. Assistant Professor of Medicine Division of Pulmonary Medicine University of Tennessee Health Science Center Memphis, TN
T. S. HAKIM, PH.D.
Department of Surgery SUNY Health Science Center Syracuse, NY J. M. MAAREK, PH.D. H. K. CHANG, PH.D.
Department of Biomedical Engineering University of Southern California Los Angeles, CA 1. Hakim TS, Maarek JM, Chang HK. Estimation of pulmonary capillary pressure in intact dog lungs using the arterial occlusion technique. Am Rev Respir Dis 1989; 140:217-24. 2. Holloway H, Perry M, Downey J, Parker J, Taylor A. Estimation of effective pulmonary capillary pressure in intact lungs. J Appl Physiol1983; 54:846-51.
USE AND MISUSE OF METERED-DOSE INHALERS BY PATIENTS WITH CHRONIC LUNG DISEASE
To the Editor: We read with great interest the recent report by de Blaquiere and colleagues (1) concerning instruction methods with metered-dose inhalers (MDI). Studies of this quality in patient education are needed, and we applaud the authors of this report. The abstract indicated "verbal instruction alone is as effective as verbal instruction supplemented with a visual aid...." This statement can be misleading if one only reads the abstract. Further reading of the methods reveal that this "verbal instruction" included demonstration of each step and allowing the patient to practice. We believe that it is critically important to emphasize demonstration in teaching as well as observation of the patient's technique; that is, simply talking about correct use is not sufficient. In addition, printed instructions alone are clearly not adequate. Self and coworkers (2) compared printed instructions with verbal instructions and demonstrations via either personal instruction or a videotape. Both the videotape and personal instructions were superior teaching methods to the printed information. Despite the relative success of both methods (1), roughly 20070 of incorrect users remained incorrect overall after instruction. In addition, 10070 of patients had problems with timing of activation ofMDI and inhalation. If one extrapolates these results to the asthma and COPD populations in the United States of over 20 million people, then 10 to 20% is a very large number of people who need further instruction or help with extender devices, dry powder inhalers, or other new inhalation devices. While this extrapolation may only give a rough estimate, it is consistent with other studies showing a similar percentage of patients who have great difficulty learning to use a plain MDI without additional teaching aids (e.g., sound device used by Shim and Williams) (3). Regarding the problem in the study by de Blaquiere and colleagues of insufficient breath-holding, we have found through our study (2) and many years of patient instruction that clearly showing the patient you are using your fingers to count to 10 is very effective. With rare exception, patients rivet on health professionals as they count to 10 with their fingers after using the MDI. We hope this simple technique will be useful to others.
I. De Blaquiere P, Christensen DB, Carter WB, Martin TR. Use and misuse of metered-dose inhalers by patients with chronic lung disease: a controlled, randomized trial of two instruction methods. Am Rev Respir Dis 1989; 140:910-6. 2. Self TH, Brooks JB, Lieberman P, Ryan MR. The value of demonstration and role of the pharmacist in teaching the correct use of pressurized bronchodilators. Can Med Assoc J 1983; 128:129-31. 3. Shim C, Williams MH. The adequacy of inhalation of aerosol from canister nebulizers. Am J Med 1980; 69:891-4.
From the Authors: Wewould like to thank Drs. Self and Rumbak for their comments. We suspect that a demonstration and also time for the patient to practice are important components of effective teaching, but we did not design our study to test these aspects of the teaching protocol. Our study was designed primarily to test the usefulness of a supplemental visual aid that would give the patient a visible cue about the timing of canister nebulizer activation. We also were interested in patient characteristics that were associated with correct or incorrect use. As Drs. Self and Rumbak point out, the results suggest that there is a very large number of patients that need instruction about the proper use of these devices. The results also indicate that health care workers need to make a point of repeating the instructions to insure that patients maintain the proper technique of nebulizer use over time. PATi~.ICIA DE BLAQUIERE, M.S., M.P.H., R.PH.
President, de Blaquiere & Associates, Inc., RS. ThOMAS R. MARTIN, M.D.
Pulmonary and Critical Care Medicine Veterans Administration Medical Center Associate Professor of Medicine University of Washington School of Medicine Seattle, WA
VENOUS THROMBOEMBOLISM
To the Editor: I compliment the comprehensive review of Dr. Moser on venous thromboembolism (1). In the section on treatment, Dr. Moser states, "When the diagnosis of acute venous thrombosis is made, immediate institution of heparin is indicated." A clinical problem that warrants further discussion is the risk versus the benefit of treating isolated calf vein deep venous thrombosis in the elderly. This decision is commonly encountered because in ambulatory patients with documented deep venous thrombosis, up to 42070 have isolated calf vein thrombosis (2). The natural history of isolated calf vein thrombosis, and subsequent need for treatment in unselected populations, is controversial (3-6). The weight of data supports the concept that the majority of isolated calf deep venous thrombosis do not propagate proximally and that complications, including pulmonary embolism, occur almost exclusively in patients with proximal propagation of the thrombus (4). Serial impedance plethysmography has been shown to be sensitive and specific for the detection of proximal vein thrombosis and can be used serially to follow patients for proximal propagation of isolated calf vein thrombosis (7). Also
1604
of use in detecting proximal thrombosis, but not documented with serial testing, is real-time B-mode ultrasonography (8). The risks of anticoagulant therapy in the elderly are substantial. During initial in-hospital anticoagulant therapy with heparin in patients 60 to 79 years of age, the incidence of major bleeding is approximately 12010. In patients older than 80 years of age, the risk of major bleeds during hospitalization increases to 22%. The incidence of minor bleeding was an additional 14 to 22% in the two age groups, respectively. This is remarkably greater than the incidence of major and minor bleeding in patients younger than 60 years of age (3% major and 4% minor bleeding) (9). The risks of anticoagulant therapy continue when the patient leaves the hospital on warfarin. The cumulative incidence of major bleeding over a 12-month period, measured in a cohort of 172 patients older than 65 years of age started on warfarin upon discharge from the hospital, was 18%. This compares to a 70/0 incidence of major bleeds in patients younger than 65 years of age (10). In conclusion, given the very high risk of anticoagulant therapy in the elderly, the low rate of complications of isolated calf vein thrombosis, and the safety of serial noninvasive testing, a prudent approach to treatment of deep venous thrombosis in the elderly would be to obtain serial noninvasive tests in those patients clinically suspected of having deep venous thrombosis and to withhold initiation of anticoagulant therapy unless proximal vein thrombosis is documented. NEIL S. SKOLNIK, M.D.
Assistant Director Family Practice Residency Abington Memorial Hospital Abington, PA 1. Moser KM. Venousthromboembolism. Am Rev Respir 1990; 141:235-49. 2. Rollins DL, Semrow CM, Friedell ML, Lloyd WE, Buchbinder D. Origin of deep vein thrombi in an ambulatory population. Am J Surg 1988; 156:122-5. 3. Dalen JE, Hirsh J, et al. American College of Chest Physicians and the National Heart, Lung, and Blood Institute National Conference on Antithrombotic Therapy. Arch Intern Med 1986; 146:462-72. 4. Philbrick JT, Becker OM. Calf deep venous thrombosis: a wolf in sheep's clothing? Arch Intern Med 1988; 148:2131-8. 5. Moser KM, LeMoine JR. Is embolic risk conditioned by location of deep venous thrombosis? Ann Intern Med 1981; 94(Part 1:439-44). 6. Lagerstedt CI, Olsson CG, Fagher BO, Oqvist BW, Albrechtsson U. Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis. Lancet 1985; 2:515-8.
7. Huisman MV, Buller HR, Cate JW, Vreeken J. Serial impedance plethysmography for suspected deep venous thrombosis in outpatients, the Amsterdam General Practitioner study. N Engl J Med 1986; 314:823-8. 8. Lensing AWA, Prandoni P, et al. Detection of deep-vein thrombosis by real-time B-mode ultrasonography. N Engl J Med 1989; 320:342-5. 9. Landefeld CS, Cook EF, Flatley M, Weisberg M, Goldman L. Identification and preliminary validation of predictors of major bleeding in hospitalized patients starting anticoagulant therapy. Am J Med 1987; 82:703-13. 10. Landefeld CS, Goldman L. Major bleeding in outpatients treated with warfarin: incidence and prediction by factors known at the start of outpatient therapy. Am J Med 1989; 87:144-52.
From the Author: Dr. Skolnik raises two points that are certainly worthy of consideration. The first relates to the need for treating patients with calflimited venous thrombosis. As his references indicated, our group was the first to raise the issue of whether such thrombi actually required treatment. The issue remains somewhat controversial. In my view, the correct policy is not to treat calf-limited thrombosis if one is prepared to followthe patient serially with impedance plethysmography for 10to 14days to assure that proximal extension does not occur. The use of the ultrasound technic in the context has not yet been validated in inpatients. Thus, the physician does have options, but one of them is not to withhold treatment and fail to follow the patient's course with validated noninvasive testing. The second point he raises is also valid - and controversial. There is a very wide range of reported incidences of bleeding, either on short-term or long-term anticoagulant therapy. The risk relates to many factors such as how the drugs were administered, how closely the patients are followed, age, the presence of coincident disease. Indeed, our major contraindication to long-term anticoagulant therapy relates more to reliability of the patient (that is, the prospect of noncompliance) than to anyone of the other known risk factors. Unsaid in my reviewis the policy I have of incorporating the patient into decision-making in controversial areas. We do this routinely and as "truth" evolves,one's best safeguard is to do so. There is risk in not treating; there is risk in treating. The patient who assumes the risk needs to participate in these decisions. KENNETH M. MOSER, M.D.
Professor of Medicine Director, Pulmonary and Critical Care Medicine University of California, San Diego Medical Center San Diego, CA
the reliability of the arterial occlusion technique for estimation of the capillary pressure. We would point out, however, that systematic differences in the analysis of the postarterial occlusion technique tracings can lead to systematic error in the estimated capillary pressure, however small. Thus, it is important to define one best set of criteria to eliminate inconsistencies due to method of analysis. With continued contributions from different investigators, this hopefully will be accomplished.
TIMafHY H. SELF, PHARM.D.
Professor of Clinical Pharmacy Department of Clinical Pharmacy MARK J. RUMBAK, M.D. Assistant Professor of Medicine Division of Pulmonary Medicine University of Tennessee Health Science Center Memphis, TN
T. S. HAKIM, PH.D.
Department of Surgery SUNY Health Science Center Syracuse, NY J. M. MAAREK, PH.D. H. K. CHANG, PH.D.
Department of Biomedical Engineering University of Southern California Los Angeles, CA 1. Hakim TS, Maarek JM, Chang HK. Estimation of pulmonary capillary pressure in intact dog lungs using the arterial occlusion technique. Am Rev Respir Dis 1989; 140:217-24. 2. Holloway H, Perry M, Downey J, Parker J, Taylor A. Estimation of effective pulmonary capillary pressure in intact lungs. J Appl Physiol1983; 54:846-51.
USE AND MISUSE OF METERED-DOSE INHALERS BY PATIENTS WITH CHRONIC LUNG DISEASE
To the Editor: We read with great interest the recent report by de Blaquiere and colleagues (1) concerning instruction methods with metered-dose inhalers (MDI). Studies of this quality in patient education are needed, and we applaud the authors of this report. The abstract indicated "verbal instruction alone is as effective as verbal instruction supplemented with a visual aid...." This statement can be misleading if one only reads the abstract. Further reading of the methods reveal that this "verbal instruction" included demonstration of each step and allowing the patient to practice. We believe that it is critically important to emphasize demonstration in teaching as well as observation of the patient's technique; that is, simply talking about correct use is not sufficient. In addition, printed instructions alone are clearly not adequate. Self and coworkers (2) compared printed instructions with verbal instructions and demonstrations via either personal instruction or a videotape. Both the videotape and personal instructions were superior teaching methods to the printed information. Despite the relative success of both methods (1), roughly 20070 of incorrect users remained incorrect overall after instruction. In addition, 10070 of patients had problems with timing of activation ofMDI and inhalation. If one extrapolates these results to the asthma and COPD populations in the United States of over 20 million people, then 10 to 20% is a very large number of people who need further instruction or help with extender devices, dry powder inhalers, or other new inhalation devices. While this extrapolation may only give a rough estimate, it is consistent with other studies showing a similar percentage of patients who have great difficulty learning to use a plain MDI without additional teaching aids (e.g., sound device used by Shim and Williams) (3). Regarding the problem in the study by de Blaquiere and colleagues of insufficient breath-holding, we have found through our study (2) and many years of patient instruction that clearly showing the patient you are using your fingers to count to 10 is very effective. With rare exception, patients rivet on health professionals as they count to 10 with their fingers after using the MDI. We hope this simple technique will be useful to others.
I. De Blaquiere P, Christensen DB, Carter WB, Martin TR. Use and misuse of metered-dose inhalers by patients with chronic lung disease: a controlled, randomized trial of two instruction methods. Am Rev Respir Dis 1989; 140:910-6. 2. Self TH, Brooks JB, Lieberman P, Ryan MR. The value of demonstration and role of the pharmacist in teaching the correct use of pressurized bronchodilators. Can Med Assoc J 1983; 128:129-31. 3. Shim C, Williams MH. The adequacy of inhalation of aerosol from canister nebulizers. Am J Med 1980; 69:891-4.
From the Authors: Wewould like to thank Drs. Self and Rumbak for their comments. We suspect that a demonstration and also time for the patient to practice are important components of effective teaching, but we did not design our study to test these aspects of the teaching protocol. Our study was designed primarily to test the usefulness of a supplemental visual aid that would give the patient a visible cue about the timing of canister nebulizer activation. We also were interested in patient characteristics that were associated with correct or incorrect use. As Drs. Self and Rumbak point out, the results suggest that there is a very large number of patients that need instruction about the proper use of these devices. The results also indicate that health care workers need to make a point of repeating the instructions to insure that patients maintain the proper technique of nebulizer use over time. PATi~.ICIA DE BLAQUIERE, M.S., M.P.H., R.PH.
President, de Blaquiere & Associates, Inc., RS. ThOMAS R. MARTIN, M.D.
Pulmonary and Critical Care Medicine Veterans Administration Medical Center Associate Professor of Medicine University of Washington School of Medicine Seattle, WA
VENOUS THROMBOEMBOLISM
To the Editor: I compliment the comprehensive review of Dr. Moser on venous thromboembolism (1). In the section on treatment, Dr. Moser states, "When the diagnosis of acute venous thrombosis is made, immediate institution of heparin is indicated." A clinical problem that warrants further discussion is the risk versus the benefit of treating isolated calf vein deep venous thrombosis in the elderly. This decision is commonly encountered because in ambulatory patients with documented deep venous thrombosis, up to 42070 have isolated calf vein thrombosis (2). The natural history of isolated calf vein thrombosis, and subsequent need for treatment in unselected populations, is controversial (3-6). The weight of data supports the concept that the majority of isolated calf deep venous thrombosis do not propagate proximally and that complications, including pulmonary embolism, occur almost exclusively in patients with proximal propagation of the thrombus (4). Serial impedance plethysmography has been shown to be sensitive and specific for the detection of proximal vein thrombosis and can be used serially to follow patients for proximal propagation of isolated calf vein thrombosis (7). Also
1604
of use in detecting proximal thrombosis, but not documented with serial testing, is real-time B-mode ultrasonography (8). The risks of anticoagulant therapy in the elderly are substantial. During initial in-hospital anticoagulant therapy with heparin in patients 60 to 79 years of age, the incidence of major bleeding is approximately 12010. In patients older than 80 years of age, the risk of major bleeds during hospitalization increases to 22%. The incidence of minor bleeding was an additional 14 to 22% in the two age groups, respectively. This is remarkably greater than the incidence of major and minor bleeding in patients younger than 60 years of age (3% major and 4% minor bleeding) (9). The risks of anticoagulant therapy continue when the patient leaves the hospital on warfarin. The cumulative incidence of major bleeding over a 12-month period, measured in a cohort of 172 patients older than 65 years of age started on warfarin upon discharge from the hospital, was 18%. This compares to a 70/0 incidence of major bleeds in patients younger than 65 years of age (10). In conclusion, given the very high risk of anticoagulant therapy in the elderly, the low rate of complications of isolated calf vein thrombosis, and the safety of serial noninvasive testing, a prudent approach to treatment of deep venous thrombosis in the elderly would be to obtain serial noninvasive tests in those patients clinically suspected of having deep venous thrombosis and to withhold initiation of anticoagulant therapy unless proximal vein thrombosis is documented. NEIL S. SKOLNIK, M.D.
Assistant Director Family Practice Residency Abington Memorial Hospital Abington, PA 1. Moser KM. Venousthromboembolism. Am Rev Respir 1990; 141:235-49. 2. Rollins DL, Semrow CM, Friedell ML, Lloyd WE, Buchbinder D. Origin of deep vein thrombi in an ambulatory population. Am J Surg 1988; 156:122-5. 3. Dalen JE, Hirsh J, et al. American College of Chest Physicians and the National Heart, Lung, and Blood Institute National Conference on Antithrombotic Therapy. Arch Intern Med 1986; 146:462-72. 4. Philbrick JT, Becker OM. Calf deep venous thrombosis: a wolf in sheep's clothing? Arch Intern Med 1988; 148:2131-8. 5. Moser KM, LeMoine JR. Is embolic risk conditioned by location of deep venous thrombosis? Ann Intern Med 1981; 94(Part 1:439-44). 6. Lagerstedt CI, Olsson CG, Fagher BO, Oqvist BW, Albrechtsson U. Need for long-term anticoagulant treatment in symptomatic calf-vein thrombosis. Lancet 1985; 2:515-8.
7. Huisman MV, Buller HR, Cate JW, Vreeken J. Serial impedance plethysmography for suspected deep venous thrombosis in outpatients, the Amsterdam General Practitioner study. N Engl J Med 1986; 314:823-8. 8. Lensing AWA, Prandoni P, et al. Detection of deep-vein thrombosis by real-time B-mode ultrasonography. N Engl J Med 1989; 320:342-5. 9. Landefeld CS, Cook EF, Flatley M, Weisberg M, Goldman L. Identification and preliminary validation of predictors of major bleeding in hospitalized patients starting anticoagulant therapy. Am J Med 1987; 82:703-13. 10. Landefeld CS, Goldman L. Major bleeding in outpatients treated with warfarin: incidence and prediction by factors known at the start of outpatient therapy. Am J Med 1989; 87:144-52.
From the Author: Dr. Skolnik raises two points that are certainly worthy of consideration. The first relates to the need for treating patients with calflimited venous thrombosis. As his references indicated, our group was the first to raise the issue of whether such thrombi actually required treatment. The issue remains somewhat controversial. In my view, the correct policy is not to treat calf-limited thrombosis if one is prepared to followthe patient serially with impedance plethysmography for 10to 14days to assure that proximal extension does not occur. The use of the ultrasound technic in the context has not yet been validated in inpatients. Thus, the physician does have options, but one of them is not to withhold treatment and fail to follow the patient's course with validated noninvasive testing. The second point he raises is also valid - and controversial. There is a very wide range of reported incidences of bleeding, either on short-term or long-term anticoagulant therapy. The risk relates to many factors such as how the drugs were administered, how closely the patients are followed, age, the presence of coincident disease. Indeed, our major contraindication to long-term anticoagulant therapy relates more to reliability of the patient (that is, the prospect of noncompliance) than to anyone of the other known risk factors. Unsaid in my reviewis the policy I have of incorporating the patient into decision-making in controversial areas. We do this routinely and as "truth" evolves,one's best safeguard is to do so. There is risk in not treating; there is risk in treating. The patient who assumes the risk needs to participate in these decisions. KENNETH M. MOSER, M.D.
Professor of Medicine Director, Pulmonary and Critical Care Medicine University of California, San Diego Medical Center San Diego, CA
