Respiratory Care Clinics Of North America[JOURNAL]
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200 papers
Humidification of respired gases in neonates and infants.
Schiffmann H
Respir Care Clin N Am · 2006 Jun · PMID 16828698 · Publisher ↗
Which temperature and humidity is optimal and can be recommended to the clinician? Some authors advocate the delivery of gas at body temperature and 100% relative humidity, which is equivalent to a water content of 44 mg...
Which temperature and humidity is optimal and can be recommended to the clinician? Some authors advocate the delivery of gas at body temperature and 100% relative humidity, which is equivalent to a water content of 44 mg/L [5,88,89]. They argue that energy neutrality is the best indicator of optimum humidity and that the intubated airway cannot be equated with the natural airway. Water loss as well as temperature and humidity gradients along the airway are necessary for mucociliary clearance and maintenance of the liquid layer of the airway epithelium, however [3]. Theoretical considerations and long-lasting experience in clinical practice support a setting that mirrors physiologic conditions even in the intubated airway. Thus, saturated gas at a temperature of 330 degrees to 35 degrees C should be delivered to the airway threshold of ventilated neonates and infants. Heated humidifiers and some HMEs can comply with these conditions. With active humidification (primarily the condensation of water) over humidification or possible malfunctions must be kept in mind. The neonatologist must consider increase in deadspace, water-retention capability, leak around the tracheal tube, and the slight increase in airway resistance when using HMEs. HMEs should not be used during weaning from ventilatory support in babies who have a body weight less than 2500 g.
The use of filters with small infants.
Whitelock DE, de Beer DA
Respir Care Clin N Am · 2006 Jun · PMID 16828697 · Publisher ↗
The use of breathing system filters may be particularly beneficial in small infants, compared with older children and adults, because of their greater need for warming and humidification of inspired gases as well as thei...
The use of breathing system filters may be particularly beneficial in small infants, compared with older children and adults, because of their greater need for warming and humidification of inspired gases as well as their increased susceptibility to lower respiratory tract contamination. The only evidence available regarding the safety and efficacy of breathing system filters in small infants comes from a few small studies conducted on intensive care patients, however. These studies have suggested that the use of HME filters may be effective in preserving body temperature and airway humidity while decreasing fluid build-up in the breathing system and therefore reducing breathing system contamination. Nonetheless, the use of filters has not been shown to decrease the incidence of VAP in small infants. In contrast,their use in adult intensive care patients, particularly those requiring prolonged ventilation, has been associated with a decrease in the infection rate. The use of breathing system filters is not associated with a statistically significant increase in the rate of complications, despite the potentially greater hazards associated with their use in small infants compared with older children and adults. In practice the use of breathing system filters, even in small infants, rarely causes any major clinical problems that cannot be prevented with a high degree of vigilance and appropriate monitoring. This vigilance is particularly important to prevent the serious morbidity and even mortality that may result from filter occlusion; when subjected to excessive loading, smaller filters are more prone to obstruction than are their larger counterparts. The increased resistance provided by smaller filters should not translate into a clinically significant increase in the work of breathing during general anesthesia, because it is common practice to ventilate small infants for all but the shortest of surgical procedures. An increase in the work of breathing may, however, become more significant when spontaneous ventilation is established at the end of a surgical case. It remains unclear whether the use of filters allows the safe reuse of breathing systems in small infants. None of the breathing system filters tested by the MHRA had a zero-percent penetrance to sodium chloride particles, and pediatric filters generally had a higher penetrance than their adult counterparts. This finding suggests that there is a potential, albeit small, risk of cross-contamination. The exact risk depends on the type of filter used and on the particular patient undergoing anesthesia or ventilation in the ICU. Although no evidence has been published showing cross-infection occurring when any filter has been used in the anesthesia breathing system for adults or small infants, the level of filtration performance required to allow the safe reuse of anesthesia breathing systems in small infants remains unanswered. Because the incidence of lower respiratory tract colonization is low in unselected small infants, a study with sufficient power to answer accurately the questions regarding the safety of breathing system reuse in small infants would be very difficult to conduct. The effect of filters on post operative infection rates may in fact be of less significance than the adoption of adequate standards of hygiene (eg, hand washing and the use of gloves).Further research is needed to determine if the variations in filtration efficiency demonstrated by the MHRA have any effects on patient outcome. This research might allow setting an effective minimal level of filtration performance for breathing system filters for use in small infants. On a practical note, the publication of the MHRA assessments of breathing system filters provides a useful tool for objective comparison of the different filters available for use in small infants, even though the relevance of the flow used to test pediatric filters has been criticized. Individual institutions will need to formulate policies for the use of breathing system filters for clinical reasons as well as for cost containment or logistical reasons. These policies should be within the frameworks set out by their regulatory agencies. Any problems arising from policies that are in breach of these frame works will remain the responsibility of the individual clinicians caring for these small infants.
The impact of severe acute respiratory syndrome on the use of and requirements for filters in Canada.
Thiessen RJ
Respir Care Clin N Am · 2006 Jun · PMID 16828696 · Publisher ↗
This article begins with a brief look at the epidemiology of SARS in Canada and then discusses barrier use and potential containment strategies that could be applied to the respiratory equipment and supportive procedures...
This article begins with a brief look at the epidemiology of SARS in Canada and then discusses barrier use and potential containment strategies that could be applied to the respiratory equipment and supportive procedures that have been implicated in the spread of SARS or other respiratory infections. The article ends with a discussion of how practice and regulations have changed in Canada since SARS and some suggestions on how practice or regulations could further improve.
The reuse of breathing systems in anesthesia.
Carter JA
Respir Care Clin N Am · 2006 Jun · PMID 16828695 · Publisher ↗
The cheap manufacture of plastics compared with the relatively expensive labor-intensive cost of decontaminating medical equipment encourages the use of disposable single-use equipment. Although the manufacture and dispo...
The cheap manufacture of plastics compared with the relatively expensive labor-intensive cost of decontaminating medical equipment encourages the use of disposable single-use equipment. Although the manufacture and disposal of single-use equipment superficially would seem to have more environmental impact than reusable equipment, the processes of cleaning and decontaminating reusable items may impose an even greater cost on the environment. In a recent study at two United States hospitals, anesthetic tubing accounted for less than 10% of medical waste, about half the amount of the plastic waste generated by the cafeterias at the same two hospitals [34]. There may be a higher cost to the organization by using single-use breathing systems. One United States institution has estimated that changing from single-use to re-usable breathing systems, with a new filter for each patient, resulted in savings in initial cost and waste disposal of more than Dollars 100,000 per year [20]. In the light of current knowledge concerning infective agents, reusing breathing systems for up to 1 week with a new appropriate filter for each new patient seems to be safe practice, provided the manufacturer of the breathing system recommends such use, and the breathing system is carefully checked before each new patient.
The effect of humidification on the incidence of ventilator-associated pneumonia.
Ricard JD, Boyer A, Dreyfuss D
Respir Care Clin N Am · 2006 Jun · PMID 16828694 · Publisher ↗
Breathing systems used with heated humidifiers are associated with a rapid and high level of bacterial colonization. This colonization is considerably reduced with the use of HMEs. Breathing systems do not need to be cha...
Breathing systems used with heated humidifiers are associated with a rapid and high level of bacterial colonization. This colonization is considerably reduced with the use of HMEs. Breathing systems do not need to be changed during the entire ventilation period of a given patient unless they are visibly soiled or mechanically malfunctioning. The incidence of VAP is not influenced by the type of humidification device (heated humidifier or HME). The incidence of VAP is not affected by the duration of use of HMEs or the type of HME, but prolonging the use of a HME further reduces the risk of cross-contamination and results in considerable cost savings.
Humidification of respired gases during mechanical ventilation: mechanical considerations.
Branson RD
Respir Care Clin N Am · 2006 Jun · PMID 16828693 · Publisher ↗
Humidification of inspired gases during mechanical ventilation remains a standard of care. Optimal humidity is an elusive target and is not clearly defined in the literature. The choice of a humidification device cannot...
Humidification of inspired gases during mechanical ventilation remains a standard of care. Optimal humidity is an elusive target and is not clearly defined in the literature. The choice of a humidification device cannot be made solely on the basis of moisture output, however. The clinician must consider the effects of the device on gas exchange and spontaneous breath-ing. The author's group has used the data reviewed here to modify their previous algorithm for choosing a humidification device (see Fig. 2). Humidification requirements for noninvasive ventilation need further study.
Consequences of under- and over-humidification.
Sottiaux TM
Respir Care Clin N Am · 2006 Jun · PMID 16828692 · Publisher ↗
Respiratory mucosal and lung structures and functions may be severely impaired in mechanically ventilated patients when delivered gases are not adequately conditioned. Although under- and over-humidification of respirato...
Respiratory mucosal and lung structures and functions may be severely impaired in mechanically ventilated patients when delivered gases are not adequately conditioned. Although under- and over-humidification of respiratory gases have not been defined clearly, a safe range of temperature and humidity may be suggested. During mechanical ventilation, gas entering the trachea should reach at least physiologic conditions (32 degrees C-34 degrees C and 100%relative humidity) to keep the ISB at its normal location. Clinicians must keep in mind that relative humidity is more important than absolute humidity: the warmer the gas, the higher the risk of tracheal mucosa dehydration and proximal airway obstruction. Practical assessment of the adequacy of the humidification system in use is not easy. The consistency (thin, moderate, or thick) of the patient's sputum should be evaluated regularly [47]. Full saturation of inspiratory gases is likely when water condensation is observed in the flex tube [91,92]. Nevertheless, no clinical parameter is accurate enough to detect all the effects of inadequate conditioning [45]. When mechanical ventilation is extended beyond several days, adequate conditioning of respiratory gases becomes increasingly crucial to prevent retention of secretions and to maximize mucociliary function; a requirement that respiratory gases reach at least physiologic conditions is appropriate.
Standards for humidification and filtration devices.
Stevens J
Respir Care Clin N Am · 2006 Jun · PMID 16828691 · Publisher ↗
This synopsis of the background to the standardization of medical devices allows a comparison of the functional operation of two regulatory authorities, the FDA and the European Commission. It can be seen that with time...
This synopsis of the background to the standardization of medical devices allows a comparison of the functional operation of two regulatory authorities, the FDA and the European Commission. It can be seen that with time they have developed many common features. However, there remains a significant difference with the older style of regulation imposed by the FDA, in particular the obligation to comply with USA Federal Law and Federal Codes of Regulation. Further, the FDA expects manufacturers, when submitting medical devices for approval, to provide their own supportive evidence by showing compliance with ISO and IEC good manufacturing practice and safety standards. Finally, it is only pragmatic to accept that marketing permission for all devices is ultimately overseen, inspected and enforced solely by the FDA. By comparison, within Europe it is the more modern Medical Device Directives of the European Commission that are the statutory legislation. In order to market a medical device, the only fundamental responsibility of the manufacturer is that it must have a CE marking, which is achieved by showing compliance with the Essential Requirements. One means of accomplishing this is to conform with the provisions of relevant harmonized standards. Such concurrence may be verified if needed, by one of the international pool of independent Notified Bodies, who are ultimately overseen by the Competent Authorities of the individual States of the Community. The preparation of standards for medical devices is a slow process, involving the cooperation of the multiple stakeholders with an interest in the device. They are expected to produce a final document that is fair, consistent and practical for all the parties involved, from the initial designer to the final patient to whom the device is attached. Analysis of the three standards applicable to humidifiers, HME and BSF demonstrates some of the difficulties encountered in meeting these obligations. It is to be hoped that the solutions which were found achieve the ultimate goal of all medical device standards-specifically that the equipment should not cause a hazard to either the patient or user. But it is interesting to wonder whether it can be shown that any BSF meets one of the prime requirements of the FDA, to wit that all medical devices must be able to demonstrate efficacy. There is a dearth of clinical trials supporting the allegation of BSF manufacturers that the routine use of these devices improves patient care, which can only be taken to mean that to date such claims are difficult to vindicate. This paralogism must be countered by the indisputable fact that BSF can significantly increase the work of breath-ing, enlarge the deadspace and even, as has been shown recently, result ina complete blockage of the breathing system. Whatever standards are in place with reference to any particular medical device, it must never be forgotten that it is only the clinician who will finally be accountable for the safe and effective operation of the equipment. While caveat emptor must always be the shibboleth of the purchaser, statutory or advisory regulations are no defense for an incompetent user.
Filtration of respired gases: theoretical aspects.
Thiessen RJ
Respir Care Clin N Am · 2006 Jun · PMID 16828690 · Publisher ↗
The filtration of aerosols and the behavior of aerosolized particles are less intuitive and more complex than commonly indicated in the medical literature, but once the basic principles are presented, they are not diffic...
The filtration of aerosols and the behavior of aerosolized particles are less intuitive and more complex than commonly indicated in the medical literature, but once the basic principles are presented, they are not difficult to understand or apply. Particles with diameters close to the most penetrating particle size are clearly the particles of greatest concern, interest, and value in considering the performance of different filtration devices, and this size has been identified as the standard particle size for testing respirators and breathing system filters. Although almost every level of health care now mandates the N95 (NIOSH rating) as the minimum rating for medical respirators, there is no such mandate regarding minimum efficiencies of breathing system filters. At least in North America, it still falls to each individual purchaser to ensure that these standardized tests are performed, because manufacturers adhere to these standards only on a voluntary basis. Government regulations similar to NIOSH 42 CFR 84 are needed for breathing system filters and should include a rating system such as N95, N99, or N100. For breathing system filters, the BFE and VFE tests are misleading and should be abandoned (or even better, banned) in favor of internationally recognized sodium chloride tests. Until then, manufacturers will be hesitant to abandon their BFE and VFE data, which give the appearance of vastly better performance than does the sodium chloride test.
Devices used to humidify respired gases.
Rathgeber J
Respir Care Clin N Am · 2006 Jun · PMID 16828689 · Publisher ↗
The efficiency of HMEs decreases with increasing tidal volumes. HMEs always result in an elevation of the inspiratory and expiratory airway resistances; this should be considered especially in cases that involve spontane...
The efficiency of HMEs decreases with increasing tidal volumes. HMEs always result in an elevation of the inspiratory and expiratory airway resistances; this should be considered especially in cases that involve spontaneous respiration. The pressure drop across HMEs should be less than 2 hPa for a flow of 60 L/min, a level that also has been measured for cascade humidifiers.HMEs with a hygroscopic coating of CaCl2 should be given preference over LiCl-coated ones, especially because products of the same efficiency are available with CaCl2 coating. Lithium is a potentially toxic substance that can be taken up by way of bronchopulmonary resorption after accidental washing out [37]. Therefore, a possible safety hazard cannot be eliminated, especially in neonates and babies. Not least for these reasons HMEs must never be combined with active humidification systems or medication nebulizers. Even if the reduction in functional efficiency of the HME that is caused by washing off of the coating of hygroscopic substances is disregarded, the presence of medication aerosols in the HME, in particular, can result in a dangerous increase in resistance to gas flow. The internal volumes of HMEs should be as small as possible so that they do not increase the effective deadspace too much. A combination of HMEsand catheter mounts results in a further increase in the deadspace, and there-fore, must be considered critically, especially in cases that involve spontaneous respiration. If a catheter mount is necessary to add flexibility to the breathing system, the HME preferably should be connected directly onto the tracheal tube with the catheter mount behind it; otherwise, the humidification efficiency of the HME will be reduced by condensation in the catheter mount. Children should be ventilated with special HMEs that have a small internal volume. Caution is required in patients who have elevated sputum production, pulmonary trauma with bleeding, pulmonary edema, or a similar condition;in such patients a partial obstruction of the HME with a resulting elevation of the airway resistances might occur. In patients who have very viscous secretions (eg, as a result of a primary pulmonary disease or long-term dehydration therapy), heated humidifiers with a set temperature of greater than 370 degrees C should be given preference. Several recent investigations showed that not every device that is designated as an HME is appropriate for conditioning respiratory gases (ie, it effectively humidifies the inspiratory air). Most of the products that are available on the market are, at best, adequate for anesthetic ventilation or short-term postoperative follow-up ventilation. Generally, this is true of all HMEs that have not been coated with hygroscopic substances. CoatedHMEs have a much better humidification efficiency; however, here too, the existence of substantial differences in quality among the products prohibits an uncritical application.
Humidification: measurement and requirements.
Züchner K
Respir Care Clin N Am · 2006 Jun · PMID 16828688 · Publisher ↗
Humidification measurement is now feasible, but it is cumbersome and costly for routine use. The user therefore may rely on data supplied with the humidification device and obtained according to ISO standards. For compar...
Humidification measurement is now feasible, but it is cumbersome and costly for routine use. The user therefore may rely on data supplied with the humidification device and obtained according to ISO standards. For comparison purposes it would be extremely helpful if both standards used to describe humidification properties quoted performance values in the same manner, preferably as moisture loss measured as milligrams of water per liter at the maximum tidal volume. The acceptable water loss should be between 0 and 7 mg/L water depending on the specific situation of the patient.
The humidification and filtration functions of the airways.
Shelly MP
Respir Care Clin N Am · 2006 Jun · PMID 16828687 · Publisher ↗
The mucociliary elevator is a highly evolved organ that humidifies inspired gases and protects the lungs from particulate, chemical, and microbiologic matter. Studies of disorders mucus and ciliary function have improved...
The mucociliary elevator is a highly evolved organ that humidifies inspired gases and protects the lungs from particulate, chemical, and microbiologic matter. Studies of disorders mucus and ciliary function have improved the understanding of this forgotten organ. The clinical implications of this understanding have yet to be explored.
Accreditation of sleep disorders programs.
Robertson B
Respir Care Clin N Am · 2006 Mar · PMID 16530652 · Publisher ↗
The accreditation of a sleep program ensures a high quality of care for the patient who has a sleep disorder. With more sleep laboratories becoming available, accreditation may be the best single way for a consumer to de...
The accreditation of a sleep program ensures a high quality of care for the patient who has a sleep disorder. With more sleep laboratories becoming available, accreditation may be the best single way for a consumer to determine the adequacy of the facility. The process for accreditation requires the sleep program to develop policies and procedures that meet rigorous national and local standards. By adhering to protocols that have been proven to outline the optimal care for any given disorder associated with sleep, the provider of that care can assure the public that the program will deliver the appropriate treatment for these problems.
Sleep medicine management: clinic-based, laboratory testing, and durable medical equipment.
Robertson B
Respir Care Clin N Am · 2006 Mar · PMID 16530651 · Publisher ↗
The patient who is suffering from a sleep disorder is seeking help for one of the basic necessities of life: a good night's sleep. For all those who have developed a problem in sleeping, whether it is physiologic or psyc...
The patient who is suffering from a sleep disorder is seeking help for one of the basic necessities of life: a good night's sleep. For all those who have developed a problem in sleeping, whether it is physiologic or psychologic, the sleep medicine profession can be literally a lifesaver.
Safety in the sleep laboratory.
Hobby MK
Respir Care Clin N Am · 2006 Mar · PMID 16530650 · Publisher ↗
The importance of workplace safety cannot be understated. The safety of employees affects morale, attendance, and workman's compensation. Federal organizations and agencies have provided guidelines to help ensure the hea...
The importance of workplace safety cannot be understated. The safety of employees affects morale, attendance, and workman's compensation. Federal organizations and agencies have provided guidelines to help ensure the health and safety of the technician and the patients who visit the sleep center. This article discusses commonly encountered hazards and ways to address them.
The effect of medication on sleep.
Brown WD
Respir Care Clin N Am · 2006 Mar · PMID 16530649 · Publisher ↗
Understanding the role that medication has on sleep is difficult for many reasons. Most medications have not been sufficiently studied to determine their primary effects on sleep and waking behavior. Because of the incre...
Understanding the role that medication has on sleep is difficult for many reasons. Most medications have not been sufficiently studied to determine their primary effects on sleep and waking behavior. Because of the increased awareness of the importance of sleep to health and well being, the effects of a new drug on sleep and waking behavior should be a mandatory element of the clinical trials process. Even when the effects of a drug are known, the medication may act differently in normal individuals and individuals who are ill. The interaction of many medications would be difficult to predict,and acute effects may be quite different from chronic use. Even a general idea about the effects of a medication will help the sleep medicine specialist understand and interpret the polysomnogram and MSLT accurately.
Psychiatric and neurologic disorders that affect sleep.
Dozier J
Respir Care Clin N Am · 2006 Mar · PMID 16530648 · Publisher ↗
Neurologic and psychiatric disorders that affect sleep are linked by a common symptom: insomnia. For this reason the overnight attended polysomnogram is a vital diagnostic tool for the clinician who wishes to determine t...
Neurologic and psychiatric disorders that affect sleep are linked by a common symptom: insomnia. For this reason the overnight attended polysomnogram is a vital diagnostic tool for the clinician who wishes to determine the cause of the sleep disturbance. The role of a well-trained and competent polysomnographer is vital to the collection of reliable diagnostic data. Understanding the symptoms and clinical manifestations of these disorders helps the polysomnographer recognize and address the challenges that can arise during the overnight polysomnographic record collection and ensure an accurate diagnosis.
Medical disorders and their effects on sleep.
Lee-Chiong TL
Respir Care Clin N Am · 2006 Mar · PMID 16530647 · Publisher ↗
Disturbances of sleep can be encountered in many medical disorders. Conversely, sleep impairment can adversely affect the symptoms of a variety of medical conditions, including respiratory, cardiac, gastrointestinal, ren...
Disturbances of sleep can be encountered in many medical disorders. Conversely, sleep impairment can adversely affect the symptoms of a variety of medical conditions, including respiratory, cardiac, gastrointestinal, renal, rheumatologic, and infectious disorders. More than one sleep pathology may be present in a particular patient, and these disorders may interact to increase the severity or prolong the duration of sleep disturbance.
Overview of sleep disorders.
Roldan G, Ang RC
Respir Care Clin N Am · 2006 Mar · PMID 16530646 · Publisher ↗
Sleep disorders are common and can affect anyone, from every social class and every ethnic background. It is estimated that more than 70 million Americans are afflicted by chronic sleep disorders. Currently about 88 slee...
Sleep disorders are common and can affect anyone, from every social class and every ethnic background. It is estimated that more than 70 million Americans are afflicted by chronic sleep disorders. Currently about 88 sleep disorders are described by the International Classification of Sleep Disorders as established by The American Academy of Sleep Medicine. This article describes the dyssomnias and parasomnias most commonly seen in the clinical setting of the sleep disorder clinic or laboratory.
Actigraphy.
Acebo C, LeBourgeois MK
Respir Care Clin N Am · 2006 Mar · PMID 16530645 · Publisher ↗
Actigraphy is a methodology for recording and analyzing activity (movement) from small, computerized devices worn on the body. Published reports on the reliability and validity of actigraph measures, although not compreh...
Actigraphy is a methodology for recording and analyzing activity (movement) from small, computerized devices worn on the body. Published reports on the reliability and validity of actigraph measures, although not comprehensive, generally indicate that sleep estimated by scoring algorithms is relatively consistent with PSG-scored sleep for normal individuals across the lifespan and for some patient groups. Accuracy is often greatly decreased when sleep is disordered or disrupted. Although actigraphy maybe suitable for documenting and evaluating some sleep disorders, its role in clinical diagnosis is limited. Actigraphy is a useful methodology for investigating group differences, sleep-pattern variations over time, and the effects of behavioral or treatment interventions. Controlling artifacts is extremely important, and using some form of daily log is essential for documenting events. The recording period should be long enough to provide reliable measures and to capture important variations across time.
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