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Controlled mechanical ventilation is characterized by a fixed breathing frequency and tidal volume. Physiological and mathematical models have demonstrated the beneficial effects of varying tidal volume and/or inspiratory pressure during positive-pressure ventilation. The addition of noise (random changes) to a monotonous nonlinear biological system, such as the lung, induces stochastic resonance that contributes to the recruitment of collapsed alveoli and atelectatic lung segments. In this article, we review the mechanism of physiological pulmonary variability, the principles of noise and stochastic resonance, and the emerging understanding that there are beneficial effects of variability during mechanical ventilation.

Fundamental to respiratory care practice are airway management, noninvasive monitoring, and invasive mechanical ventilation. The purpose of this paper is to review the recent literature related to these topics in a manner that is most likely to have interest to the readers of Respiratory Care.

This paper will present a focused and personal history of physiologic monitoring, beginning with the discovery of modern anesthesia and its development from a technical practice to a scientific discipline. Emphasis will be on the essence of monitoring in the anesthesia evolution, and this work will attempt to answer the question of how to evaluate the impact of monitoring on patient outcome. Understanding that monitors are passive and that only caregivers using monitors can impact outcome is at the crux of this approach to analysis. The limited quality data involving monitoring analysis, including that from pulse oximetry, will be discussed and critiqued. The invention and rapid spread of pulse oximetry will be highlighted and used as an example throughout, but the principles developed will apply to other monitors and patient monitoring in general. The problems created by monitoring alarms will also be discussed.

Tracheostomy is one of the most common procedures performed in the intensive care unit. Indications, risks, benefits, timing and technique of the procedure, however, remain controversial. The decision of when and how to perform a tracheostomy is often subjective, but must be individualized to the patient. The following review gives an update on recent literature related to tracheostomy in the critically ill.Surprisingly, few data are available on the current practice of tracheostomy in the intensive care unit setting. Very few trials address this issue in a prospective, randomized fashion (randomized controlled trial). Most reports include small numbers representing a heterogeneous population, describing contrary results and precluding any definite conclusions. Evidence seems to suggest that early tracheostomy, however, might be preferable in selected patients.Due to increased experience and advanced techniques, percutaneous tracheostomy has become a popular, relatively safe procedure in the intensive care unit. The question of appropriate timing, however, has not been definitely answered with a randomized controlled trial. Instead, a number of retrospective studies and a single prospective study have shed some light on this issue. Most reports favor the performance of tracheostomy within 10 days of respiratory failure.

Objective To review published data on the team model of intensive care unit (ICU) care delivery. Design Nonexhaustive, selective literature search. Setting Review of literature published in the English language. Patients/subjects Humans cared for in ICUs. Interventions None. Results The team model for delivery of ICU care reduces mortality, ICU length of stay, hospital length of stay, and cost of care. Convincing data suggest that merely having daily rounds led by an intensivist enhances patient care significantly. Further improvements can be obtained by maintaining a nurse-to-patient ratio of no greater than 1:2, adding critical care pharmacists, and providing dedicated respiratory therapists to the ICU team. Conclusion Current and looming shortages of all ICU healthcare providers is a barrier to universal implementation of the team model. Advocating for the ICU team model for critical care delivery requires local, regional, national, and international activities for success.

Critical care medicine trainees and faculty must acquire and maintain the skills necessary to provide state-of-the art clinical care to critically ill patients, to improve patient outcomes, optimize intensive care unit utilization, and continue to advance the theory and practice of critical care medicine. This should be accomplished in an environment dedicated to compassionate and ethical care.A multidisciplinary panel of professionals with expertise in critical care education and the practice of critical care medicine under the direction of the American College of Critical Care Medicine.Physician education in critical care medicine in the United States should encompass all disciplines that provide care in the intensive care unit and all levels of training: from medical students through all levels of postgraduate training and continuing medical education for all providers of clinical critical care. The scope of this guideline includes physician education in the United States from residency through ongoing practice after subspecialization.Relevant literature was accessed via a systematic Medline search as well as by requesting references from all panel members. Subsequently, the bibliographies of obtained literature were reviewed for additional references. In addition, a search of organization-based published material was conducted via the Internet. This included but was not limited to material published by the American College of Critical Care Medicine, Accreditation Council for Graduate Medical Education, Accreditation Council for Continuing Medical Education, and other primary and specialty organizations. Collaboratively and iteratively, the task force met, by conference call and in person, to construct the tenets and ultimately the substance of this guideline.Guidelines for the continuum of education in critical care medicine from residency through specialty training and ongoing throughout practice will facilitate standardization of physician education in critical care medicine.

Sedation of the critically ill patient without an artificial airway is a difficult and challenging clinical problem. Careful attention to preparations, selection of appropriate techniques, and monitoring of patient responses during sedation will reduce problems in this patient population. Preparation to provide airway support is essential in the sedation of these patients, and the appropriate training of the clinician is important.

Information and opinions were sought on the need for graduating and practicing respiratory therapists to obtain 66 competencies necessary for practice in 2015 and beyond, the required length of respiratory care programs, the educational needs of practicing therapists, current and future workforce positions, and the appropriate credential needed by graduating therapists.Survey responses from respiratory therapy department directors or managers are the basis of this report. After pilot testing and refining the questions, a self-administered, Internet based, American Association for Respiratory Care (AARC) endorsed survey was used to gather information from 2,368 individuals designated as respiratory therapy department directors or managers in the AARC membership list as of May 2010.A total of 663 valid survey responses (28.0%) were received. On average, the vacancy rate of surveyed hospitals was only 0.81 full-time equivalents (FTEs). Responses by directors on 66 competencies described in the second 2015 conference as needed by graduate and practicing respiratory therapists indicated 90% agreement on 37, between 50% and 90% agreement on 25, and50% agreement on 4 competencies. There was no consensus among directors on the academic preparation of new graduates, with 245 (36.8%) indicating a preference for a baccalaureate or master's degree, 243 (36.7%) indicating a preference for an associate degree, and 176 (26.5%) indicating no preference. There were 270 (41.8%) respondents who indicated that a baccalaureate or master's degree in respiratory therapy should be required to qualify for a license to deliver respiratory care. The survey indicated that 523 (81.2%) of directors are in favor of the RRT credential being required to practice in 2015 and beyond.There was good agreement that graduate and practicing therapists should obtain the vast majority of the 66 competencies surveyed and that the entry level credential should be the RRT. Similar numbers of managers favored an entry level baccalaureate degree as favored an associate degree.

As background for the American Association for Respiratory Care (AARC) third 2015 and Beyond conference, we sought information and opinions on the ability of the current respiratory therapy education infrastructure to make changes that would assure competent respiratory therapists in the envisioned healthcare future.After pilot testing and refining the questions, we invited the directors of 435 respiratory therapy programs (based in 411 colleges) that were fully accredited or in the process of being accredited by the Commission on Accreditation for Respiratory Care as of May, 2010, to participate in the survey.Three-hundred forty-eight program directors (80%) provided valid survey responses. Three of the 5 competencies related to evidence-based medicine and respiratory care protocols were taught less often in the associate-degree programs than in the baccalaureate-degree programs. Eighty percent of the baccalaureate-degree programs, compared to 42% of the associate-degree programs, instruct students how to critique published research (P.001). Only 34% of the associate-degree programs teach students the general meaning of statistical tests, compared to 78% of the baccalaureate-degree programs (P.001). Ninety-four percent of the baccalaureate-degree programs, versus 81% of the associate-degree programs, teach the students to apply evidence-based medicine to clinical practice (P = .01). Teaching students how to describe healthcare and financial reimbursement systems and the need to reduce the cost of delivering respiratory care (a leadership competency identified by the second 2015 and Beyond conference) was significantly more common in the baccalaureate-degree programs (72%) than in the associate-degree programs (56%) (P = .03). Other competencies showed trends toward differences, and the baccalaureate-degree programs reported higher percentages of success than the associate-degree programs.There are important differences between the baccalaureate-degree and associate-degree programs.

The American Association for Respiratory Care established a task force in late 2007 to identify likely new roles and responsibilities of respiratory therapists (RTs) in the year 2015 and beyond. A series of 3 conferences was held between 2008 and 2010. The first task force conference affirmed that the healthcare system is in the process of dramatic change, driven by the need to improve health while decreasing costs and improving quality. This will be facilitated by application of evidence-based care, prevention and management of disease, and closely integrated interdisciplinary care teams. The second task force conference identified specific competencies needed to assure safe and effective execution of RT roles and responsibilities in the future. The third task force conference was charged with creating plans to change the professional education process so that RTs are able to achieve the needed skills, attitudes, and competencies identified in the previous conferences. Transition plans were developed by participants after review and discussion of the outcomes of the first two conferences and 1,011 survey responses from RT department managers and RT education program directors. This is a report of the recommendations of the third task force conference held July 12-14, 2010, on Marco Island, Florida. The participants, who represented groups concerned with RT education, licensure, and practice, proposed, discussed, and accepted that to be successful in the future a baccalaureate degree must be the minimum entry level for respiratory care practice. Also accepted was the recommendation that the Certified Respiratory Therapist examination be retired, and instead, passing of the Registered Respiratory Therapist examination will be required for beginning clinical practice. A date of 2020 for achieving these changes was proposed, debated, and accepted. Recommendations were approved requesting resources be provided to help RT education programs, existing RT workforce, and state societies work through the issues raised by these changes.

To determine characteristics of patients requiring readmission to an intensive care unit (ICU).Retrospective case-control chart review.Adult patients in an 8-bed medical and 16-bed surgical ICU in a 650-bed university teaching hospital during an 18-month period.None.Each patient readmitted to either ICU was compared to a single control patient matched for age, sex, unit, and diagnosis. A total of 117 variables were obtained from chart review. The last value for each variable before ICU discharge was used. Chi-square analysis, linear regression factor analysis, correlation, and Student's t-test were used to identify significant factors predicting the patient's return to an ICU. Descriptive statistics were used to describe various subgroups.Mortality rate was 41.5% in the 82 readmitted patients (comprising 4.6% of the total ICU admissions) and only 7.3% in the controls. Mean (+/- SD) hospital length of stay was 47.8 +/- 42.0 days in the study group and 20.8 +/- 14.2 days (p.0009) in the controls. Initial ICU length of stay was 8.3 +/- 16.1 days in the readmitted group and 4.0 +/- 5.0 days (p = .02) in the controls. Variables that predicted readmission to the ICU were: increased respiratory rate (24.2 vs. 20 breaths/min, p.002), lower hematocrit value (31.9% vs. 34.4%, p = .01), positive fluid balance (p.03), and positive blood cultures (six in the readmitted group, none in the controls, p = .002). More than 30% of readmissions were for a recurrence or worsening of the original problem. Fifty-four percent of the patients were readmitted with pulmonary failure. Mortality rate in both groups was related to advanced age, Acute Physiology and Chronic Health Evaluation (APACHE II) scores at ICU discharge, and increased blood urea nitrogen concentrations. Mortality rate in the control group, but not in the readmitted group, correlated with the level of consciousness, serum creatinine concentration, and use of hemodialysis.Readmission to an ICU carries a risk of high mortality rate and increased length of stay and may represent premature discharge in at least 30% of patients. Pulmonary failure is the immediate cause of readmission in more than half of the readmitted patients. Increased respiratory rate correlates with ICU readmission. Intermediate care areas for patients with poor pulmonary function may help to avoid readmission to an ICU, prevent death, and conserve hospital resources.

This article discusses the therapeutic and toxic effects of sedative drugs and neuromuscular blocking agents in the critically ill patient. Common misconceptions of drug properties are highlighted and dispelled. A rational plan for the use of each type of drag is described. The appropriate use of sedative drugs may cause withdrawal syndromes; treatment options are outlined.

Pulmonary artery catheters are frequently used and may be the cause of pulmonary artery rupture. The “feel” of balloon inflation, a clinical sign of a “wedged” catheter, was noted to vary among different manufacturers' catheters. The inflation pressures of five catheters from four manufacturers were examined in the laboratory. Peak pressures ranged from 475 ± 10 mm Hg to 1,037 ± 36.8 mm Hg. Plateau pressures ranged from 220 ± 4 mm Hg to 495 ± 2.9 mm Hg. Catheters with high inflation pressures may make detection of a wedged catheter by feel impossible and, thus, may increase the risk of a pulmonary artery rupture.

Evaluation of the impact on clinical care of improved, innovative oximetry technology.Randomized, prospective trial.Postcardiac surgery intensive care unit in a major teaching hospital.A total of 86 patients after undergoing coronary artery bypass surgery.All patients were monitored with two oximeters, one employing conventional oximetry (conventional pulse oximeter, CPO) and one using an improved innovative technology (innovative pulse oximeter, IPO), on different fingers of the same hand. The outputs from both devices were collected continuously by computer, but only one device was randomly selected and displayed for clinicians.The amount and percentage of nonfunctional monitoring time was collected and found to be much greater for the CPO than the IPO (8.7% +/- 16.4% for CPO vs. 1.2% +/- 3.3% for IPO, p =.000256). Time to extubation was not different between the two groups (634 +/- 328 mins for IPO vs. 706 +/- 459 mins for CPO). Clinicians managing patients with the more reliable IPO weaned patients faster to an FIO2 of 0.40 (176 +/- 111 mins for IPO vs. 348 +/- 425 mins for CPO, p =.0125), obtained fewer arterial blood gas measurements (2.7 +/- 1.2 for IPO vs. 4.1 +/- 1.6 for CPO, p =.000015), and made the same number of ventilator changes during this weaning process (2.9 +/- 1.2 for IPO vs. 2.9 +/- 1.7 for CPO).Provision of more reliable oximetry allows caregivers to act in a more efficient and cost-effective manner in regard to oxygen weaning and use of arterial blood gas measurements. Investigating the effect of a monitor on the process of care, rather than simply its accuracy and precision, is a useful, relevant paradigm for evaluating the value and impact of a new technology.

The number of anesthesiology residents pursuing critical care medicine (CCM) fellowship training has been decreasing in recent years. A significant number of training positions remain unfilled each year. Possible causes of this decline were evaluated by surveying residents regarding their attitudes toward practice and training in CCM. All 38 anesthesiology programs having accredited CCM fellowships were surveyed. Four of these and one program without CCM fellowships were used to develop the survey instrument. Four programs without CCM fellowships and 34 programs with CCM fellowships make up the survey group. Returned were 640 surveys from 37 (97%) programs accounting for over 30% of the possible residents. Resident interest in pursuing CCM training decreased as year of residency increased (P < 0.0001). Residents in programs with little patient care responsibility during intensive care unit (ICU) rotations expressed less interest in CCM training (P < 0.012). The administrative role of the anesthesiology department in the ICU also influenced resident interest (P < 0.014). Written responses to open-ended questions suggested resident concerns with the following: stress of chronic care, financial consequences of additional year of training, ICU call frequency and load, ICU role ambiguity, and shared decision-making in the ICU. A recurring question was, "Are there jobs (outside of academics) for anesthesiologist intensivists?" Most residents knew a CCM anesthesiologist they admired and knew that there were unfilled fellowship positions available. Defining the job market, improving curriculum and teaching, supporting deferment of student loans, and introducing residents and medical students to the ICU earlier may increase the interest in CCM practice among anesthesiology residents.

Temporary dual chamber atrioventricular (AV) pacing is often used to increase cardiac output (CO) after cardiac surgery. The AV interval was varied to investigate the effect on CO in 13 patients. CO was computed from the Fick principle using mixed venous oxygen saturation (SvO2), arterial oxygen saturation (SaO2), hemoglobin, and oxygen consumption (VO2). AV intervals were varied randomly from 0.025 to 0.300 seconds in 0.025-second increments. The effect on CO from increasing the AV interval was dependent on the control CO. In all patients, as the AV interval was increased from 0.025 to 0.100 seconds, CO progressively increased. In most patients, the highest (optimal) CO occurred with AV pacing and averaged 300 mL/min greater than with atrial (A) pacing alone (P.0001). In patients with a high initial CO (6.0 L/min), CO peaked and averaged 0.5 L/min more than with A pacing. CO was maximal for each of these patients at a unique AV interval between 0.100 and 0.225 seconds, and at intervals greater than 0.225 seconds CO decreased (P.01). In patients with intermediate CO (4-6 L/min) at AV intervals greater than 0.100 seconds, a plateau in CO was reached. No consistent pattern was seen in patients with low initial CO (4.0 L/min). Maximal CO may be achieved by optimizing the AV interval in patients following cardiac surgery. The optimal AV interval is between 0.100 and 0.225 seconds and is different for each patient. Continuous SvO2 monitoring allows rapid evaluation of CO changes and optimization of the AV pacing interval.

Acid base disorders—computer-aided learning software on CD-ROM consists of two clinical cases illustrating the use of acid-base analysis in clinical decision making. In an active form of learning, the student must make choices to confirm diagnoses and make management decisions. Tutoring and “consultation” with an expert are available throughout the entire process. Incorrect diagnoses are critiqued, and the user is directed to the “library” for additional study. Multiple-choice questions are presented throughout each scenario, and a record of student performance is displayed. Each case consists of five parts: brief history, clinical assessment, chemical assessment, diagnosis and treatment, and resolution–summary. Following the case, the student is presented with several brief cases and questions. A set of essay questions are …

The electronic explosion has resulted in a large number of medically oriented materials appearing for home computer use. Major medical book publishers have joined the rush to this market. Mosby's Pulmonary and Critical Care Medicine on CD-ROM, subtitled "your single source reference library," attempts to fill the gap between the dated material in current textbooks and up-to-date journal information. This CD-ROM contains the complete text and most of the graphs and charts fromPulmonary and Critical Care Loose-leaf, Year Book of Pulmonary Medicine(1993, 1994, 1995),Year Book of Critical Care Medicine(1993, 1994, 1995), andCurrent Pulmonology(volumes 14,15,16). The major advantage of this format over print is the ability to quickly search the material in a variety of ways to retrieve and organize the information in a userdefined way. The search engine is intuitive and rapid. Highlighting, custom bookmarks, and a reader-created note file linked to the

This CD-ROM produced by Churchill Livingstone medical publishers offers continuing medical education (CME) credit hours and an opportunity to review and practice resuscitation activities. The user interface is very hightech multimedia. A fast processor, sound card, CD-ROM drive, and at least 8 MB of RAM are necessary to fully appreciate the program's features. The stated educational goal of The Virtual Physician is to simulate an actual patient sustaining a cardiac arrest in an emergency department setting. Although the effects are excellent, the simulation fails to be realistic. This is not a fault of the concept but a problem of the computer-student interface, which is limited by unrealistic actions of a mouse or any pointing device. The program is true to the learning goals of traditional advanced cardiac life support (ACLS) courses, emphasizing the use of initial defibrillation in ventricular fibrillation and reviewing the arrhythmia treatment algorithms. The program offers several

To the Editor. —As the Executive Committee of the Board of Directors of American Society of Critical Care Anesthesiologists, the largest American subspecialty group of anesthesiologists and intensivists, we write to raise several points about the recent article by Dr Connors and colleagues on the RHC 1 and its accompanying Editorial. 2 We commend Connors et al for their attempt to examine the efficacy and safety of the RHC in a large cohort of critically ill (medical) patients. Their finding that the use of the RHC "was associated with an increased risk of mortality" certainly warrants further investigation. The explanations proposed by the authors are interesting, raising the possibility that the aggressive, interventional style of management practiced in some ICUs is hazardous rather than beneficial. An alternative explanation, that the "benefits of RHC may not be realized if the physician interpreting the output of the catheter is not knowledgeable and skilled in its

INTRODUCTION EXPERIMENTS herewith reported were made in connection with the investigational activities of the Food and Drug Administration to support enforcement of the Federal Food, Drug, and Cosmetic Act against misbranded drugs for livestock and poultry. When the occasion demands, remedies are tested on a “class basis” to evaluate their particular merit in a given field of disease. This can be done when many remedies in a particular category, which contain a common basic ingredient, are recommended for a specific disease or condition. In this instance, attention was drawn to almost universally made recommendations for copper sulfate as a remedy for crop mycosis in poultry caused by the fungus Candida albicans. Interest was concentrated in the validity of such recommendations when the literature revealed a paucity of factual evidence to support copper sulfate as a competent treatment of moniliasis (crop mycosis). This article presents critical information collected from the experimental …

Hydrochloric acid (HCl) infusions for the correction of metabolic alkalosis have been used for 20 yr. In the critical care setting, HCl is usually infused through a central venous or pulmonary artery (PA) catheter. In two patients receiving HCl infusions through a PA catheter, we observed and examined solid yellow particulate material in the aspirating syringe while testing the proximal lumen for patiency. We carried out in vitro investigation infusing PA catheters with 0.1, 0.2, 0.3, and 0.4 normal HCl at 20 degrees, 38 degrees, and 42 degrees C for 24 and 48 h. Although frank catheter deterioration could not be documented, the surface and interior of those catheters infused with greater than 0.1 normal HCl changed texture, indicating a change in catheter composition. Exceeding a concentration of 0.1 normal is not recommended when HCl is infused through PA catheters.

The effects of intravenous dantrolene sodium, alone and in combination with verapamil, upon atrioventricular conduction, cardiovascular function, and neuromuscular function were studied in chloralose-urethane anesthetized dogs. Hemodynamic variables (systemic arterial, central venous, and pulmonary arterial pressures and cardiac output) and His-bundle electrograms were monitored, and measurements were made during atrial pacing at 175 beats/min, as well as at the spontaneous heart rate. In one part of the study animals received dantrolene sodium incrementally at 30-min intervals to cumulative doses of 1, 2.5, 5, and 10 mg/kg. Subsequently, verapamil was administered incrementally at 30-min intervals to cumulative doses of 0.1, 0.2, 0.4, and 0.6 mg/kg. In the second part of the study, dogs received identical dosage sequences, but verapamil preceded dantrolene administration. Dantrolene caused no significant depression of atrioventricular conduction or cardiac performance but did increase systemic vascular resistance at doses above 2.5 mg/kg. Verapamil alone (greater than or equal to 0.2 mg/kg) or with dantrolene (greater than or equal to 0.1 mg/kg) increased the atrial-His-bundle conduction interval. In the presence of verapamil, dantrolene (greater than or equal to 2.5 mg/kg) decreased cardiac index and increased pulmonary artery occlusion pressure. Although 0.6 mg/kg verapamil depressed cardiac index and increased pulmonary artery occlusion pressure, this effect was observed at 0.4 mg/kg after prior treatment with dantrolene. Verapamil did not augment the dose-dependent twitch depression observed with dantrolene. Dantrolene alone had no apparent effect on atrioventricular conduction and caused little enhancement of the effects of verapamil. However, each drug appeared to enhance the myocardial depressant effects of the other.