Kevin J. Inman

A retrospective review of a large cohort of patients undergoing the process of withholding or withdrawal of life support

OBJECTIVES To determine the proportion of patients who died as a result of the withdrawal or withholding of life support (WD/WHLS) in the intensive care units (ICUs) of three teaching hospitals and to describe the process involved by determining: a) why the decision was made to withdraw support (WDLS); b) when WDLS took place; and c) how the WDLS process was conducted. DESIGN Retrospective cohort study. SETTING Three university-affiliated ICUs. PATIENTS Four hundred nineteen patients who died in one of three academic, tertiary care ICUs over a 1-yr period. INTERVENTIONS Retrospective chart review. Data collected included age, gender, admitting diagnoses, comorbid disease, Acute Physiology and Chronic Health Evaluation II score, and mode of death (brain death, death due to withholding of life support, death due to WDLS, or death despite ongoing therapy). For those patients dying due to WDLS, the reason for WDLS, person initiating discussion, timing of WDLS, degree of organ dysfunction, order of withdrawal of life support modalities, and the use of sedatives and analgesics were recorded. MEASUREMENTS AND MAIN RESULTS Seventy percent of patients died by WD/WHLS and 8.4% were brain dead. Patients undergoing WD/WHLS were older and had a longer length of stay than patients dying from other causes. Poor prognosis was the most common reason given for WDLS, reflected by significant organ dysfunction at the time of WDLS. Future quality of life was a less frequently cited reason. Most patients undergoing WDLS did so early in their ICU stay, although time to WDLS appeared to reflect diagnostic group. Few meetings occurred before WDLS and death occurred soon after initiating WDLS. There was a preference of withdrawing mechanical ventilation last and large amounts of morphine (mean 21 +/- 33 [SD] mg/hr) and benzodiazepines (mean 8.6 +/- 11 mg/hr) were used. Little variability in practice was apparent among the studied ICUs. CONCLUSIONS Similar to other studies, WD/WHLS was the most common cause of death in academic ICUs and poor patient prognosis was considered the most important factor in deciding on WDLS. However, in contrast to other studies, future quality of life was not as frequently cited a reason for WDLS and larger amounts of morphine were used during WDLS. These discrepancies suggest areas for potential future research.

Is there a preferred technique for weaning the difficult-to-wean patient? A systematic review of the literature

OBJECTIVE To answer the following question: In difficult-to-wean patients, which of the three commonly used techniques of weaning (T-piece, synchronized intermittent mandatory ventilation, or pressure support ventilation) leads to the highest proportion of successfully weaned patients and the shortest weaning time? DATA SOURCES Computerized literature searches in MEDLINE (1975-1996), Cinahl (1982-1996), and Healthplan (1985-1996), exploding all Mesh headings pertaining to Mechanical Ventilation and Weaning. Searches were restricted to the English language, adults, and humans. Personal files were hand searched, and references of selected articles were reviewed. STUDY SELECTION a) POPULATION Patients requiring a gradual weaning process from the ventilator (either requiring prolonged initial ventilation of >72 hrs or a failed trial of spontaneous breathing after >24 hrs of ventilation); b) INTERVENTIONS At least two of the following three modes of weaning from mechanical ventilation must have been compared: T-piece, synchronized intermittent mandatory ventilation, or pressure support ventilation; c) OUTCOMES At least one of the following: weaning time (time from initiation of weaning to extubation) or successful weaning rate (successfully off the ventilator for >48 hrs); and d) STUDY DESIGN Controlled trial. DATA EXTRACTION Two reviewers independently reviewed the articles and graded them according to their methodologic rigor. Data on the success of weaning and the time to wean were summarized for each study. DATA SYNTHESIS The search strategy identified 667 potentially relevant studies; of these, 228 had weaning as their primary focus, and of these, 48 addressed modes of ventilation during weaning. Only 16 of these 48 studies had one of the specified outcomes, and only ten of these were controlled trials. Of the ten trials, only four fulfilled all our selection criteria. The results of the trials were conflicting, and there was heterogeneity among studies that precluded meaningful pooling of the results. CONCLUSIONS There are few trials designed to determine the most effective mode of ventilation for weaning, and more work is required in this area. From the trials reviewed, we could not identify a superior weaning technique among the three most popular modes, T-piece, pressure support ventilation, or synchronized intermittent mandatory ventilation. However, it appears that synchronized intermittent mandatory ventilation may lead to a longer duration of the weaning process than either T-piece or pressure support ventilation. Finally, the manner in which the mode of weaning is applied may have a greater effect on the likelihood of weaning than the mode itself.

Assessing the efficiency of the admission process to a critical care unit: does the literature allow the use of benchmarking?

Objectives: To determine the ability of the current literature to supply appropriate data for benchmarking admission practice to a multidisciplinary critical care unit. Design: Retrospective review of data collected prospectively on

Problems in assessing the technology of critical care medicine.

Technology assessment is becoming increasingly important in the area of critical care due both to the explosion of technology associated with this discipline and to the realization that future demand for these health care resources will undoubtedly exceed the ability to pay. Technology assessment remains both confusing and controversial to many physicians. This review tries to address some of the confusion by reviewing the basic strategies involved in this process. From there, problems and prospects for the evaluation of critical care as a program are presented, followed by the assessment of components within the area of critical care. Finally, recommendations are made on how technology assessment could proceed in the future to best achieve the efficient provision of this service.

Hematocrit modifies the circulatory control of systemic and myocardial oxygen utilization in septic sheep

ObjectiveTo describe the relationship be tween hematocrit and oxygen utilization before and ofter the onset of a hyperdynamic septic state. DesignProspective, observational study. SettingLaboratory of a large university-affiliated medical school. SubjectsThirty mature sheep, each weighing 30 to 40 kg (0.9 to 1.1 m2 body surface area). InterventionsAfter baseline measurements, cecal ligation and perforation were used to establish an intra-abdominal source of infection. The abdominal wound was closed and animals were studied on the second postoperative day. An increase in cardiac output of ≥30% was used to arbitrarily define the onset of sepsis. Repeat measurements were performed and the animal was killed. ResultsThe circulatory response to this septic insult included an increase in both cardiac index (change, baseline to sepsis, Δ +2.24 ± 0.75 L/min/m2; p <.01) and myocardial blood flows (Δ +76.4 ± 56 mL/100 g/min; p < .01). We found a negative correlation between the hematocrit and cardiac index (r2 = .21; p < .01) during the septic study, and noted that the amount (p < .01) of this correlation was significantly greater in the septic than the nonseptic study. Concurrently, the negative correlation observed between hematocrit and whole-body oxygen extraction (r2 = .21;p < .01) was significantly lower (p < .01) across the range of hematocrit values examined during the septic study vs. the similar relationship in the nonseptic study (r2 = .27;p < .01). The increase in myocardial oxygen consumption paralleled the relationship between cardiac work and hematocrit in the septic study, and was accompanied by incresases in both myocardial blood flows (r2 = .25; p < .01) and myocardial oxygen extraction (r2 = .35;p<.01). ConclusionsThe normal circulatory compensation to anemia in hyperdynamic sepsis includes increases in cardiac index and whole-body oxygen extraction, although greater reliance is likely placed on the use of systemic flow reserve to maintain tissue oxygen uptake in septic vs. healthy study conditions. Furthermore, increased reliance on myocardial oxygen extraction in sepsis suggests that the normal flow-reserve supporting myocardial oxygen availability may be limited in this syndrome. (Crit Care Med 1994; 22:470–479)

Ventilatory care in a selection of Ontario hospitals: bigger is not necessarily better!

ObjectiveTo determine whether there is variability in the structure and process of ventilatory care in intensive care units (ICUs) of the hospitals of Southwestern Ontario.DesignSelf-administered questionnaire-based survey.SettingICUs of selected community and teaching hospitals of Southwestern Ontario.ParticipantsHead of respiratory therapy service of respective hospitals; in those hospitals without respiratory therapists, the ICU nurse manager.InterventionSelf-administered questionnaire.Outcome measure(s)The availability of different models of ventilators and respiratory therapist and physician coverage were assessed. In addition, the use of clinical practice guidelines, respiratory therapists, and the nursing role in ventilatory care were determined.ResultsIn general, the structure of ventilatory care, including availability of different modes of ventilation, and coverage by respiratory therapists and physicians was more comprehensive in larger hospitals. However, the availability of some modes of ventilation varied more than expected among hospitals of comparable size. Similarly, variability in the process of ventilatory care, defined by the availability of clinical practice guidelines and the roles of respiratory therapists varied both within and among hospitals of different size.ConclusionsThe structure and process of ventilatory care in this sample of Southwestern Ontario ICUs was found to be variable. Not all this variability could be accounted for by hospital size, suggesting a potential for improvement in overall ventilatory care. Further study is required before any specific recommendations can be considered.

PRESSURE ULCER PREVENTION WITH LOW-AIR-LOSS BEDS. REPLY

In Reply. —Thank you for allowing us to respond to concerns expressed by Dr Verdery regarding our article, which examined the clinical utility and cost-effectiveness of an air suspension bed in the prevention of pressure ulcers. First, he was concerned about the lack of blinding in the diagnosis and categorization of stage I ulcers. As stated in our methods, blinding was impossible. Therefore, we instituted a process to minimize this bias as much as possible. Specifically, with detection and staging of a pressure ulcer by the study nurse, our hospitals skin care team was consulted. The consultant dermatologist then independently addressed the issue of presence or absence of pressure ulcers and staged them when applicable. Our interrater agreement was good (κ>0.80). Second, Verdery noted we had not mentioned whether a specific treatment protocol was instituted. The studys objective was to address prevention, not treatment. Thus, treatment of established ulcers was