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Palo Alto, CA
Mr. Demers is a Clinical Specialist, Respiratory Care Department, Lucile Salter Packard Children’s Hospital, Stanford University Medical Center.
Correspondence to: Bob Demers, BS, RRT, Respiratory Care Department, Lucile Salter Packard Children’s Hospital at Stanford, 725 Welch Rd, Palo Alto, CA 94304; e-mail: BobDemers{at}AOL.com
Certain airborne agents have been unequivocally demonstrated to elicit lung disease, heart disease, and cancer in a dose-related fashion. The landmark studies of Auerbach and colleagues,1 published in this journal in 1976, forcefully demonstrated that cigarette smoke is a potent provocateur of coronary artery disease. The striking correlation between intimal thickening of the coronary arteries and cigarette consumption was compelling: "Advanced hyaline thickening was found in 90.7% of those smoking two or more packs per day, in 48.4% of those smoking less than one pack per day, and not in any of those who never smoked regularly."1 Similarly, the risk of contracting lung disease (pulmonary asbestosis) and cancer (mesothelioma) is known to be directly related to cumulative exposure to airborne asbestos particles.
In this issue of CHEST (see page 1048), Dimich and co-workers present the results of a study that purports to demonstrate that aerosolized ribavirin, as well as aerosolized pentamidine isethionate, can trigger reactive airway disease (RAD) in respiratory care practitioners (RCPs) who are repeatedly exposed to trace amounts of those agents in the course of their work. The suggestion that RCPs might be singularly vulnerable to RAD by virtue of their choice of profession is not new. Kern and Frumkin2 contended that asthma is an occupational hazard for RCPs in an article published in 1989. Kern subsequently collaborated with Christiani in another study,3 also demonstrating an apparent susceptibility to RAD among RCPs. But they stopped short of implicating airborne pharmaceuticals as etiologic agents in either of those reports. If the contention of Dimich and co-workers is correct, the incidental and sporadic exposure of caregivers to trace amounts of aerosolized pharmaceutical agents is capable of eliciting airway reactivity, although the patients who are receiving vastly higher doses of those drugs have not been shown to be at increased risk of RAD. This would be a curious situation indeed! In a recent editorial, I have suggested that the proclivity for RCPs to acquire RAD might be attributable to their exposure, not to aerosolized drugs, but rather to bacteria-laden microaerosols and/or airborne endotoxins.4
Of course, we wouldn’t need to fret about caregivers’ susceptibility to airborne bacteria/endotoxins on the one hand, or aerosolized drugs on the other, if these contaminants were not allowed to access the bedside environment in the first place. Patients are routinely counseled against sharing their prescription drugs with friends or family members. We would be well advised to heed our own advice, by taking the requisite steps to prevent ourselves from inhaling the aerosolized drugs prescribed for our patients! Kacmarek and Kratohvil5 described the employment of a double-walled scavenging system that can be used when administering ribavirin to nonintubated patients, and documented the effectiveness of that strategy. And in 1986 we published an article6 detailing the methods that we had developed at Stanford University Medical Center, whereby ribavirin aerosol could be scrubbed from the expirate of patients receiving mechanical ventilation who are receiving that agent. This serves to protect the valve box of the ventilator, as well as any patients/caregivers who might happen to be in the vicinity of the machine, from being bombarded with ribavirin particles. Of course, caregivers’ concerns with respect to their incidental exposure to ribavirin aerosol has markedly abated in recent years, simply because that agent is now rarely, if ever, employed for the treatment of respiratory syncytial virus (H. Rodriguez, MD; personal communication; June 2002). However, aerosolized pentamidine isethionate continues to be a popular agent for the prophylaxis of Pneumocystis carinii pneumonia. In the outpatient clinics of our pediatric hospital, it is not unusual for us to administer four or more pentamidine treatments on a given day. We have modified the Respirgard (Marquest Medical Products; Englewood, CO), the nebulizer system that was expressly specified by the US Food and Drug Administration for the delivery of pentamidine aerosol, by interfacing it to an airtight soft-cushion mask. This modification allows us not only to contain pentamidine aerosol within the confines of the mask, but also to trap any tuberculosis droplet nuclei that might be generated secondary to aerosol-triggered coughing. This is an important factor to consider when dealing with patients who are immunocompromised, and might unwittingly harbor active tuberculosis. So-called "pentamidine booths" have been created to cope with this hazard, but having a toddler sit in an airtight booth that isolates the child from his/her parents is not a practical alternative. In a sense, the airtight, soft-cushion mask might be considered to be a "booth for the face." When we tested the Respirgard circuit that had been modified in this manner, an unforeseen bonus was observed to emerge. Pentamidine deposition roughly doubled,7 owing to the fact that the mask apparently serves as a spacer or holding chamber. The Respirgard system, as supplied by the manufacturer, already incorporates a breathing circuit filter, the Marquest MQ-303. Admittedly, one’s ability to sequester particles, intended for the patient, within the circuit will be crucially linked to the competence of that filter. Unfortunately, one of our sharp-eyed RCPs noted that a faintly visible plume of pentamidine could be observed to traverse the MQ-303 filter during administration of that agent! For that reason, we require that our therapists mount an ultraefficient breathing circuit filter (Conserve 50; Pall Corporation; East Hills, NY) on the outlet of the MQ-303.4 Any reader who might be interested in learning the specifics of our methodology is invited to supply me with an e-mail address to which I will post an electronic file containing a thoroughly detailed slide show. This slide show, written as a portable document format (PDF) file, is readable using Adobe Acrobat Reader software (Adobe Systems Incorporated; San Jose, CA), which is itself downloadable, free of charge, from the Adobe Web site.
Clinicians have enough to think about as they pursue their day-to-day activities of administering care to patients. Worrying about potential exposure to aerosolized drugs, airborne pathogens, and/or endotoxins shouldn’t need to be added to our list of concerns. And, separate and distinct from that issue, drugs that are prescribed for patients should be taken by patients, and should not be shared by the practitioners who are obliged to be within arm’s length. I would respectfully suggest that this epitomizes the most literal and rigorous application of the "patient-centered care" ideal that constitutes the core of our clinical practice.
References
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