Autonomic Nervous System Function and Depth of Article Critique

Excerpt from Article Critique :

Autonomic nervous system function and depth of sedation in adults receiving mechanical ventilation.

The authors of the article were attempting to discover how the autonomic nervous system affected the depth of sedation which occurred when a patient was placed on mechanical ventilation. The reason for this concern was that patients have been known to have adverse effects due to changes in the autonomic functions during critical illness. The stated thesis of the article is to understand autonomic responses better.

This study was part of a larger study which monitored patients for a 24-hour period "in the medical respiratory and coronary care ICUs at Virginia Commonwealth University." The study chose patients who were not compromised by receiving neuromuscular blocking agents and had no scalp lacerations or skull abnormalities. The patients had to be more than 18 years old at the time of the trial. Patients heart rate variability and sedative state were constantly monitored during the research.

The main finding from the study was that "deep sedation was associated with depressed parasympathetic nervous activity and that measures of sympathetic nervous activity and heart rate did not change with changes in the depth of sedation." From this finding the researchers believe that measuring heart rate variance in the ICU is justified in some situations. The specific situation would be when the patients with cardiac disease because there can be related cardiac complications as a result of the depressed heart rate variability. However, the authors suggest that further study which was targeted specifically at this issue may be warranted. Their study was based on secondary data.

2. Clorhexedine, toothbrushing, and preventing ventilator-associated pneumonia in critically all adults.

The main thrust of the article was to determine if there is a specific measure that can be taken to reduce the amount of patients who contract pneumonia when they are placed in a ventilator. The hypothesis was that regular cleaning of the mouth and teeth could defeat the bacteria which cause pneumonia and thus reduce its occurrence. The two treatments used to determine the effectiveness of this hypothesis were tooth brushing and chlorhexidine either together as a treatment or separate.

Since it is noted that there are many factors associated with ventilation that increase the possibility that a patient will get pneumonia, it was theorized that inadequate dental care could also be a factor. The authors of the study noted that "Dental plaque can provide a habitat for microorganisms responsible for ventilator-associated pneumonia." Thus, researchers found 547 patients who met the criteria of having been intubated at least 24 hours prior to intervention, and they could not already have been infected with pneumonia. The patients were put into one of four groups -- tooth brushing only, chlorhexidine only, tooth brushing and chlorhexidine, or a control group which received normal care -- for the study.

It was found that tooth brushing by itself did not reduce the occurrence of ventilator-associated pneumonia, however when a chlorhexidine swab was used the patients were less likely to contract pneumonia. The researchers believe that, along with other measures to prevent VAP, chlorhexidine sabs should be employed since VAP is a significant issue among intubated patients.

3. Chronic critical illness: Prevalence, profile, and pathophysiology.

The authors of this study attempt to give physicians and nurse who work in the intensive care unit further understanding of chronic critical illness. All patients in an ICU are undergoing some form of acute critical illness or they would not be in the ICU. But that can turn into chronic status which makes it more difficult for the patient to recover. Chronic critical illness is marked by "recurrent episodes of instability, need for prolonged medical and nursing care, multiple organ dysfunction or failure, ongoing need for life-sustaining interventions, and uncertain trajectory for recovery." The reason for acute status changing into chronic is unknown, but the purpose of the study is to inform caregivers "essential information about the prevalence and profile of the chronically critically ill patient."

The authors of the study did not conduct their own investigation of the phenomenon with their own critically ill patients, but rater they looked at research that had been conducted already to determine the signs and effective treatments for a person with CCI. First, only approximately 6% to 10% of critically ill patients reach this threshold, but these patients account for a very large portion of ICU care costs. There was found to be no exact definition of this group of patients (historically it was associated with prolonged stays on mechanical ventilators, but that definition has changed. The authors determine a more comprehensive diagnosis. Patients who have been on a mechanical ventilator for a prolonged amount of time, have been in the ICU for a long period and who have had a prolonged need for life-sustaining technologies. The authors also found that age, early tracheotomy, readmission rate, and multiple organ dysfunction were factors associated with CCI.

4. Induced moderate hypothermia after cardiac arrest.

Research and practice has shown that inducing moderate hypothermia after a patient experiences cardiac arrest is considered a best practice. It has been found that "Ten percent to 30% of patients who survive an out-of-hospital cardiac arrest will have permanent brain damage." The preferred treatment for this for the past ten years has been to induce a moderate hypothermia following the incident. The authors say that "The purpose of this article is to provide an overview of the pathophysiology and research that supports the use of induced mild hypothermia following cardiac arrest along with nursing considerations for this patient population."

Research has shown that inducing moderate hypothermia increases the number of patients who will survive a cardiac arrest event. In a clinical study of the effects, 49% of patients who had the treatment versus 26% who did not were able to go home. The reason for this was found to be that patients who were allowed to undergo the moderate hypothermia were able to survive the loss of oxygen to the brain inherent patients who have a cardiac arrest.

The researchers found that there were two methods of hypothermia inducement -- noninvasive and invasive. Noninvasive inducement is characterized by using manual control of temperature such as ice packs, fans, alcohol baths and cooling blankets. This method was not recognized as effective because the nurse must maintain control of the patients temperature constantly. "Invasive methods include use of iced (4°C) intravenous fluids and the use of intravascular catheters." These methods were supported by research and found to be effective.

5. Intra-abdominal hypertension: Detecting and managing a lethal complication of critical illness.

Patients in the ICU are subject to a long list of complications which can severely diminish their prospects of survival or, at the very least, artificially prolong their stay in the ICU. One issue, which plagues as many as 50% of patients treated in the ICU, is intra-abdominal hypertension. "Patients at risk for intra-abdominal hypertension include those with major traumatic injury, major surgery, sepsis, burns, pancreatitis, ileus, and massive fluid resuscitation." This occurrence generally causes a prolonged stay, but it can also lead to further complications as well. Researchers found that certain patients were predisposed to IAH, those who were obese or had undergone certain procedures.

The danger of the occurrence is that it is detrimental to organ function. Because the abdominal region contains so many organs which are vital to sustained life, this can be an extremely life threatening condition. One of the primary purposes of the article is to make sure that caretakers can detect when IAH is occurring. Mostly the difference between hypertension and simple pressure is in the matter of the whether the organs in the abdominal cavity are compromised or not. Of course, testing to understand whether organ function has been affected is crucial.

The article also talks about risk factors for IAH. There are four such factors -- diminished abdominal wall compliance, increased intraluminal contents, increased peritoneal cavity contents, and capillary leak/fluid resuscitation -- that occur to warn clinicians when it is possible to have an IAH episode. To thwart this occurrence there are several measuring techniques that can be used. The caregiver can do a bladder pressure measurement, or a measurement of the abdominal pressure itself.

6. Long-term survival in the intensive care unit after erythrocyte blood transfusion.

Erythrocyte transfusion are commonly done in the ICU to "treat anemia, support hemodynamic status, minimize ischemic organ damage, and prevent mortality." Because it is anecdotally supported as an effective treatment, and has some efficacy in studies, there is an increasing wish to understand what the long-term effects are. The study under consideration looks at other studies which have given contradictory evidence when short-term mortality was the subject, and conduct there own study to see the effects of long-term mortality rates.

The study was conducted using data from a database of several different hospitals ICUs over an extended period of time. The authors also had a smaller control group which was compared to the study groups. The number of patients studied during this…

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