J. Christopher Farmer

High-frequency oscillatory ventilation for adult respiratory distress syndrome - A pilot study

OBJECTIVE To evaluate the safety and effectiveness of high-frequency oscillatory ventilation using a protocol designed to recruit and maintain optimal lung volume in patients with severe adult respiratory distress syndrome (ARDS). SETTING Surgical and medical intensive care units in a tertiary care, military teaching hospital. DESIGN A prospective, clinical study. PATIENTS Seventeen patients, 17 yrs to 83 yrs of age, with severe ARDS (Lung Injury Score of 3.81 +/- 0.23) failing inverse ratio mechanical conventional ventilation (PaO2/FiO2 ratio of 68.6 +/- 21.6, peak inspiratory pressure of 54.3 +/- 12.7 cm H2O, positive end-expiratory pressure of 18.2 +/- 6.9 cm H2O). INTERVENTIONS High-frequency oscillatory ventilation was instituted after varying periods of conventional ventilation (5.12 +/- 4.3 days). We employed lung volume recruitment strategy that consisted of incremental increases in mean airway pressure to achieve a PaO2 of > or = 60 torr (> or = 8.0 kPa), with an FiO2 of < or = 0.6. MEASUREMENTS AND MAIN RESULTS High-frequency oscillator ventilator settings (FiO2, mean airway pressure, pressure amplitude of oscillation [delta P] frequency) and hemodynamic parameters (cardiac output, oxygen delivery [DO2]), mean systemic and pulmonary arterial pressures, and the oxygenation index (oxygenation index = [FiO2 x mean airway pressure x 100]/PaO2) were monitored during the transition to high-frequency oscillatory ventilation and throughout the course of the high-frequency protocol. Thirteen patients demonstrated improved gas exchange and an overall improvement in PaO2/FiO2 ratio (p < .02). Reductions in the oxygenation index (p < .01) and FiO2 (p < .02) at 12, 24, and 48 hrs after starting high-frequency oscillatory ventilation were observed. No significant compromise in cardiac output or DO2 was observed, despite a significant increase in mean airway pressure (31.2 +/- 10.3 to 34.0 +/- 6.7 cm H2O, p < .05) on high-frequency oscillatory ventilation. The overall survival rate at 30 days was 47%. A greater number of pretreatment days on conventional ventilation (p < .009) and an entry oxygenation index of > 47 (sensitivity 100%, specificity 100%) were associated with mortality. CONCLUSIONS High-frequency oscillatory ventilation is both safe and effective in adult patients with severe ARDS failing conventional ventilation. A lung volume recruitment strategy during high-frequency oscillatory ventilation produced improved gas exchange without a compromise in DO2. These results are encouraging and support the need for a prospective, randomized trial of algorithm-controlled conventional ventilation vs. high-frequency oscillatory ventilation for adults with severe ARDS.

The Stability and Workload Index for Transfer score predicts unplanned intensive care unit patient readmission: initial development and validation.

Objective:Unplanned readmission of hospitalized patients to an intensive care unit (ICU) is associated with a worse outcome, but our ability to identify who is likely to deteriorate after ICU dismissal is limited. The objective of this study is to develop and validate a numerical index, named the Stability and Workload Index for Transfer, to predict ICU readmission. Design:In this prospective cohort study, risk factors for ICU readmission were identified from a broad range of patients’ admission and discharge characteristics, specific ICU interventions, and in-patient workload measurements. The prediction score was validated in two independent ICUs. Setting:One medical and one mixed medical-surgical ICU in two tertiary centers. Patients:Consecutive patients requiring >24 hrs of ICU care. Interventions:None. Measurements:Unplanned ICU readmission or unexpected death following ICU dismissal. Results:In a derivation cohort of 1,131 medical ICU patients, 100 patients had unplanned readmissions, and five died unexpectedly in the hospital following ICU discharge. Predictors of readmission/unexpected death identified in a logistic regression analysis were ICU admission source, ICU length of stay, and day of discharge neurologic (Glasgow Coma Scale) and respiratory (hypoxemia, hypercapnia, or nursing requirements for complex respiratory care) impairment. The Stability and Workload Index for Transfer score predicted readmission more precisely (area under the curve [AUC], 0.75; 95% confidence interval [CI], 0.70–0.80) than the day of discharge Acute Physiology and Chronic Health Evaluation III score (AUC, 0.62; 95% CI, 0.56–0.68). In the two validation cohorts, the Stability and Workload Index for Transfer score predicted readmission similarly in a North American medical ICU (AUC, 0.74; 95% CI, 0.67–0.80) and a European medical-surgical ICU (AUC, 0.70; 95% CI, 0.64–0.76), but was less well calibrated in the medical-surgical ICU. Conclusion:The Stability and Workload Index for Transfer score is derived from information readily available at the time of ICU dismissal and acceptably predicts ICU readmission. It is not known if discharge decisions based on this prediction score will decrease the number of ICU readmissions and/or improve outcome.

The provision of sophisticated critical care beyond the hospital: Lessons from physiology and military experiences that apply to civil disaster medical response

Objective:The provision of sophisticated medical care in an austere environment is challenging. During and after a mass casualty event, it is likely that critical care services will be needed beyond an intensive care unit (ICU) setting. The objective of this article is to explore existing ICU care systems such as military aeromedical transport that may be applicable to disaster medicine and to providing critical care outside of an ICU setting. Results:The U.S. Air Force Critical Care Aeromedical Transport (CCAT) Teams were developed in 1994 in response to an unmet military need for long-range air transport of critically ill and injured patients. This system has transported several thousand ICU patients and is an applicable model for the future development of extrahospital critical care capabilities needed during a disaster. We also discuss civilian aeromedical critical care systems, the types of medical devices used, and their applicability to disaster medical response. Conclusion:The U.S. Air Force CCAT Team program, as well as many civilian critical care air ambulance services, provides a workable starting point for the development of disaster medical critical care response capabilities for disaster medical systems.

Sepsis during pregnancy

Objectives:To provide a current review of the literature regarding the assessment and management of sepsis during pregnancy. Design:A comprehensive review of current English-language literature search was performed with Ovid MEDLINE using the Medical Subject Headings pregnancy and sepsis, with Medical Subject Headings or keywords seeking randomized controlled trials and clinical reports, and by reviewing the bibliographies of clinical practice guidelines. Results:Sepsis-related maternal morbidity and mortality is a significant and persistent problem in the modern critical care obstetric unit. The management of sepsis during pregnancy is challenging. The obstetric intensivist must simultaneously discern the effect of maternal physiologic changes on fetal vulnerability and the effect of the fetus on maternal status throughout the various phases of pregnancy. Little direct evidence exists to validate the extrapolation of some sepsis treatment modalities from other nonpregnant patient populations. Nevertheless, early detection, accurate diagnosis, and aggressive appropriate treatment strategies may significantly improve outcome. Approaches like the Surviving Sepsis Campaign guidelines are unproven but seem reasonable and practical. Conclusions:Sepsis during pregnancy is uncommon yet potentially fatal. Diagnostic and therapeutic guidelines should predominantly pattern those currently utilized for nonpregnant patients.

Worldwide disaster medical response: an historical perspective.

Objective:Disaster medicine and disaster medical response is a complex and evolving field that has existed for millennia. The objective of this article is to provide a brief review of significant milestones in the history of disaster medicine with emphasis on applicability to present and future structures for disaster medical response. Results:Disaster medical response is an historically necessary function in any society. These range from response to natural disasters, to the ravages of warfare, and most recently, to medical response after terrorist acts. Our current disaster response systems are largely predicated on military models derived over the last 200 yrs. Their hallmark is a structured and graded response system based on numbers of casualties. In general, all of these assume that there is an identifiable “ground zero” and then proceed with echelons of casualty retrieval and care that proceeds rearward to a hospital(s). In a civil response setting, most civilian models of disaster medical response similarly follow this military model. This historical approach may not be applicable to some threats such as bioterrorism. A “new” model of disaster medical response for this type of threat is still evolving. Using history to guide our future education and planning efforts is discussed. Conclusion:We can learn much from an historical perspective that is still applicable to many current disaster medical threats. However, a new response model may be needed to address the threats of bioterrorism.

Clinical review: Allocating ventilators during large-scale disasters – problems, planning, and process

Catastrophic disasters, particularly a pandemic of influenza, may force difficult allocation decisions when demand for mechanical ventilation greatly exceeds available resources. These situations demand integrated incident management responses on the part of the health care facility and community, including resource management, provider liability protection, community education and information, and health care facility decision-making processes designed to allocate resources as justly as possible. If inadequate resources are available despite optimal incident management, a process that is evidence-based and as objective as possible should be used to allocate ventilators. The process and decision tools should be codified pre-event by the local and regional healthcare entities, public health agencies, and the community. A proposed decision tool uses predictive scoring systems, disease-specific prognostic factors, response to current mechanical ventilation, duration of current and expected therapies, and underlying disease states to guide decisions about which patients will receive mechanical ventilation. Although research in the specifics of the decision tools remains nascent, critical care physicians are urged to work with their health care facilities, public health agencies, and communities to ensure that a just and clinically sound systematic approach to these situations is in place prior to their occurrence.

Providing critical care during a disaster: The interface between disaster response agencies and hospitals

Objective:Recent natural disasters have highlighted shortfall areas in current hospital disaster preparedness. These include the following: 1) insufficient coordination between hospitals and civil/governmental response agencies; 2) insufficient on-site critical care capability; 3) a lack of “portability” of acute care processes (i.e., patient transport and/or bringing care to the patient); 4) education shortfalls; and 5) the inability of hospitals to align disaster medical requirements with other competing priorities. Conclusions:Definition of the roles and responsibilities of a hospital during a disaster requires additional planning precision beyond the prehospital response phase. Planners must also better define plans for circumstances when or if a hospital is rendered unusable. Disaster medical training of hospital personnel has been inadequate. This article details the specifics of these issues and outlines various potential approaches to begin addressing and formulating remedies to these shortfalls.

A suggested curriculum in echocardiography for critical care physicians

Echocardiography is a powerful diagnostic and monitoring tool of cardiac performance, cardiac pathology, and extracardiac intrathoracic abnormalities. Numerous investigations in intensive care have shown its merit, being efficacious and safe. Because many obvious and/or unsuspected conditions can impact the hemodynamic status of critically ill patients, echocardiography is becoming an integral part of an intensivist’s diagnostic and monitoring armamentarium. However, significant background information, cognitive, and technical skills are required to properly perform and interpret echocardiography images. Some education and training guidelines for echocardiography have been developed while others remain “in progress.” This manuscript suggests a core curriculum and necessary training elements for intensivists. This curriculum does not segregate portable handheld surface echocardiography from the typical platforms of transthoracic echocardiography and transesophageal echocardiography, because hardware and software developments have bridged these technologies.

The initial Mayo Clinic experience using high-frequency oscillatory ventilation for adult patients: a retrospective study

BackgroundHigh-frequency oscillatory ventilation (HFOV) was introduced in our institution in June 2003. Since then, there has been no protocol to guide the use of HFOV, and all decisions regarding ventilation strategies and settings of HFOV were made by the treating intensivist. The aim of this study is to report our first year of experience using HFOV.MethodsIn this retrospective study, we reviewed all 14 adult patients, who were consecutively ventilated with HFOV in the intensive care units of a tertiary medical center, from June 2003 to July 2004.ResultsThe mean age of the patients was 56 years, 10 were males, and all were whites. The first day median APACHE II score and its predicted hospital mortality were 35 and 83%, respectively, and the median SOFA score was 11.5. Eleven patients had ARDS, two unilateral pneumonia with septic shock, and one pulmonary edema. Patients received conventional ventilation for a median of 1.8 days before HFOV. HFOV was used 16 times for a median of 3.2 days. Improvements in oxygenation parameters were observed after 24 hours of HFOV (mean PaO2/FIO2 increased from 82 to 107, P < 0.05; and the mean oxygenation index decreased from 42 to 29; P < 0.05). In two patients HFOV was discontinued, in one because of equipment failure and in another because of severe hypotension that was unresponsive to fluids. No change in mean arterial pressure, or vasopressor requirements was noted after the initiation of HFOV. Eight patients died (57 %, 95% CI: 33–79); life support was withdrawn in six and two suffered cardiac arrest.ConclusionDuring our first year of experience, HFOV was used as a rescue therapy in very sick patients with refractory hypoxemia, and improvement in oxygenation was observed after 24 hours of this technique. HFOV is a reasonable alternative when a protective lung strategy could not be achieved on conventional ventilation.

Comparison of a nurse initiated insulin infusion protocol for intensive insulin therapy between adult surgical trauma, medical and coronary care intensive care patients.

BackgroundSustained hyperglycemia is a known risk factor for adverse outcomes in critically ill patients. The specific aim was to determine if a nurse initiated insulin infusion protocol (IIP) was effective in maintaining blood glucose values (BG) within a target goal of 100–150 mg/dL across different intensive care units (ICUs) and to describe glycemic control during the 48 hours after protocol discontinuation.MethodsA descriptive, retrospective review of 366 patients having 28,192 blood glucose values in three intensive care units, Surgical Trauma Intensive Care Unit (STICU), Medical (MICU) and Coronary Care Unit (CCU) in a quaternary care hospital was conducted. Patients were > 15 years of age, admitted to STICU (n = 162), MICU (n = 110) or CCU (n = 94) over 8 months; October 2003-June 2004 and who had an initial blood glucose level > 150 mg/dL. We summarized the effectiveness and safety of a nurse initiated IIP, and compared these endpoints among STICU, MICU and CCU patients.ResultsThe median blood glucose values (mg/dL) at initiation of insulin infusion protocol were lower in STICU (188; IQR, 162–217) than in MICU, (201; IQR, 170–268) and CCU (227; IQR, 178–313); p < 0.0001. Mean time to achieving a target glucose level (100–150 mg/dL) was similar between the three units: 4.6 hours in STICU, 4.7 hours in MICU and 4.9 hours in CCU (p = 0.27). Hypoglycemia (BG < 60 mg/dL) occurred in 7% of STICU, 5% of MICU, and 5% of CCU patients (p = 0.85). Protocol violations were uncommon in all three ICUs. Mean blood glucose 48 hours following IIP discontinuation was significantly different for each population: 142 mg/dL in STICU, 167 mg/dL in MICU, and 160 mg/dL in CCU (p < 0.0001).ConclusionThe safety and effectiveness of nurse initiated IIP was similar across different ICUs in our hospital. Marked variability in glucose control after the protocol discontinuation suggests the need for further research regarding glucose control in patients transitioning out of the ICU.