ORLANDO, FLA--Late-breaking results from a placebo-controlled trial of inhaled nitric oxide showed no benefit among patients with acute respiratory distress syndrome, as reported at the 29th Educational and Scientific Program of the Society of Critical Care Medicine in Orlando, Fla. Other highlights of the meeting included a report that zinc supplementation may be harmful for critically ill patients with infections and a study showing that smoking may be linked to risk-taking behavior.

CLINICAL CRITERIA FOR OPTIMAL PA CATHETER PLACEMENT

Use of clinical criteria for optimal pulmonary artery (PA) catheter placement may allow for an 80% reduction in the need for daily chest radiographs, according to findings from a recent prospective study.

Douglas E. Houghton and colleagues from the University of Miami/Jackson Memorial Hospital in Miami, evaluated clinical criteria as evidence of catheter migration in 100 consecutive patients. In all patients, the clinical findings were compared with chest films.

The following criteria were considered evidence of correct catheter placement:

• The amount of air required to obtain a wedge tracing was 1.25 mL or greater.
• The centimeter marking of the PA catheter at the introducer hub had moved 1 cm or less.

A total of 390 chest radiograph/clinical criteria comparisons were included in this study. In 15 instances (4% of all comparisons), the chest film showed that the PA catheter needed to be repositioned. In 11 of these 15 cases (73%), the clinical criteria also suggested migration.

Overall, clinical evidence of migration had a sensitivity of 73%, a specificity of 82%, an accuracy of 81%, a positive predictive value of 14%, and a negative predictive value of 99%.

SMOKING LINKED TO RISK-TAKING BEHAVIORS

Risk-taking behaviors and a history of trauma are more common among smokers than among nonsmokers, new findings suggest. Gabriel E. Ryb, of the Atlantic City Medical Center in New Jersey, and colleagues concluded that smoking status may be used to "target a population for injury-prevention interventions."

The investigators evaluated 1,118 adult patients (mean age, 37.3 years; 72% male; 55% white) who were hospitalized in a trauma center for more than two days. The patients were interviewed and evaluated for smoking and for psychoactive substance use disorders.

About half of the patients (52%) were smokers. Smokers were more likely than nonsmokers to be male, unmarried, and younger.

Compared with nonsmokers, smokers had lower levels of education and income and had higher rates of alcohol and drug abuse and dependence. Smokers were also significantly more likely than nonsmokers to have a history of trauma and to exhibit risk-taking behaviors (Table 1).

IS ZINC GOOD OR BAD FOR THE CRITICALLY ILL?

"Don't give zinc to acutely ill patients until their inflammatory response subsides," reported Gary P. Zaloga in his review of available data on this subject. However, he added, "if a patient has a chronic zinc deficiency--particularly someone who is not actively infected or who does not have an active inflammatory response--then certainly, giving zinc seems like a good thing to do at this point in time."

Patients who have an infection or who are traumatized show decreased levels of calcium, iron, and zinc but elevated concentrations of proinflammatory cytokines. A drop in zinc may be part of the acute-phase response, Dr. Zaloga said, explaining that "it may have evolved to be protective."

Because zinc is required for synthesis and secretion of proinflammatory cytokines, giving zinc to critically ill patients could be detrimental, according to Dr. Zaloga, who is director of critical care medicine at the Washington Hospital Center in Washington, DC.

On the other hand, there is some evidence that zinc could be cytoprotective against various influences. "The data that zinc is good is equally balanced by perhaps even better information that zinc may be extraordinarily harmful if given to a patient during a systemic inflammatory response," he explained.

Some studies indicate that "zinc will induce prolific inflammatory responses, superoxide production, and perhaps organ injury." However, at the same time, some data show that it has the opposite effect, he said.

A prospective clinical trial is needed, Dr. Zaloga concluded. But for now, "if you have someone who was reasonably well nurtured, and they came in with an acute illness, and they have an acute inflammatory response, I think the gist of the data would say that zinc is going to be proinflammatory in those individuals--and we don't know what the outcome of that would be," he said.

ARDS PATIENTS MAY NOT BENEFIT FROM INHALED NITRIC OXIDE

Results of a placebo-controlled trial of inhaled nitric oxide in patients with acute respiratory distress syndrome (ARDS) failed to show any benefit in terms of the rate of extubation or the number of days alive after a successful trial of spontaneous breathing.

This 28-day study included 385 patients with ARDS who were randomized to 5 ppm inhaled nitric oxide or placebo. The two groups were similar in terms of sex, age, race, height, weight, and underlying diseases associated with ARDS, explained Robert W. Taylor, who is president of the Society of Critical Care Medicine and director of the critical care training program at St. John's Mercy Medical Center in Missouri.

Slightly more than one third of patients in both groups had no days off of the ventilator (either because they died or they could not be extubated). Similarly, in both groups about 70% of those who underwent a trial of unassisted breathing were able to be extubated. Among those who were extubated, the mean number of days spent alive and off the ventilator was similar in the two groups (approximately 11 days).

Because the success of a weaning trial is often influenced by nonrespiratory factors (eg, head injury, respiratory muscle weakness), the researchers also determined the mean number of days patients remained alive and off the ventilator after reaching extubation criteria (ie, fraction of inspired oxygen of 0.4 or less, a positive end-expiratory pressure of 5 cm H₂O or less, and an oxygen saturation of greater than 92%). This number was also similar in the two groups (approximately 17 days). About 80% in both groups had reached these oxygenation criteria.

RESPIRATORY THERAPISTS CAN INTUBATE PATIENTS

Respiratory therapists--if given adequate training--can effectively perform in-hospital endotracheal intubation, according to data from a recent study. The findings showed a high success rate among intubations performed by respiratory therapists.

Ronald F. Sing and colleagues from the Carolinas Medical Center in Charlotte, NC, prospectively examined the outcome of in-hospital endotracheal intubations performed by respiratory therapists. Data on 226 such intubations in 207 patients were included in the analysis.

Overall, 93% of the intubations were successfully performed, and 73% were successful on the first attempt. Interestingly, 10% of the successful intubations were performed after a failed attempt by a physician.

Complications included four cases of minor dental trauma and 26 cases of esophageal intubation; all of these problems were immediately identified. In addition, aspiration occurred in seven cases.

DEMOGRAPHIC CHANGES IN THE ICU

Length of stay in the medical intensive care unit (ICU) is not affected by advanced age, according to findings from a prospective 10-year study. The data suggest that "age alone should not be utilized to exclude the elderly from admission to intensive care," according to Ramarao Suresh and colleagues from the Maimonides Medical Center in Brooklyn, NY.

The researchers studied all admissions to their medical ICU during 1988 (n = 735) and 1998 (n = 984). The mean age of patients significantly increased from 74.3 years in 1988 to 82.8 years in 1998. The percentage of patients who were older than 80 years of age increased from 25% to 45% during this 10-year period, while the percentage of patients younger than age 50 years remained relatively stable (6% and 8%, respectively).

In addition, the proportion of female patients increased significantly, from 47% to 59%. Furthermore, the average length of stay decreased significantly during the study period (from 5.8 to 4.1 days) and did not differ among age-groups.

PREDICTING NEUROLOGIC OUTCOME AFTER CARDIAC ARREST

Cranial nerve reflexes and Glasgow Coma Scale score measured early after resuscitation from cardiac arrest are highly predictive of neurologic outcome, according to data from almost 1,000 patients.

Howell C. Sasser, of the University of Pittsburgh, Pennsylvania, and colleagues analyzed data from the Brain Resuscitation Clinical Trials conducted from 1979 to 1994. A total of 942 patients who were not sedated or anesthetized were followed for six months.

Outcome--as determined by Cerebral Performance Category--was significantly associated with all of the cranial nerve reflexes at both 12 and 24 hours after return of spontaneous circulation. Only a small percentage of patients (7% or less) with an absent reflex eventually reached a good outcome. None of the patients with an absent corneal or cough reflex made a good recovery. In addition, scores on the Glasgow Coma Scale at both 12 and 24 hours after resuscitation were significantly associated with outcome.

The researchers concluded that, while patients with intact signs are more likely to have good outcomes, "many survivors remain severely impaired."

EVIDENCE-BASED GUIDELINE FOR STRESS ULCER PROPHYLAXIS

An evidence-based guideline for identifying critically ill patients at low risk for stress ulceration was determined to be effective in a recent study. The benefits of the guidelines include cost savings and avoidance of adverse effects, reported Matthew P. Chow, of Northeastern Ohio Universities College of Medicine in Columbus, and colleagues.

The researchers followed 105 patients who were in the ICU for more than 24 hours. Patients with at least one of the following risk factors were considered to be at high risk and were placed on stress ulcer prophylaxis:

• Coagulopathy.
• Head trauma.
• Mechanical ventilation.
• History of upper gastrointestinal bleeding.

Sixty patients were determined to be at high risk and were given famotidine, sucralfate, lansoprazole, or gastric feedings. The researchers found evidence of upper gastrointestinal bleeding in six of the high-risk patients but none of the low-risk patients.

GENDER DIFFERENCES IN ADRENAL RESPONSE TO SHOCK

The adrenal response to shock is different between men and women, reported Michael D. Williams and colleagues from the Washington Hospital Center in Washington, DC. Their recent study showed that cortisol levels are significantly higher in women than in men during shock.

The research team followed 46 male and 42 female postoperative patients, age 18 years and older, who were taking pressors for at least 24 hours and had no recent history of supplemental steroid use.

Cortisol levels were similar among men and women who were not in shock (about 21 µg/dL for both). However, among patients in shock, cortisol levels were significantly higher in women than in men (39.3 vs 25.4 µg/dL). Near-normal cortisol levels were found more frequently among men in shock than among women in shock. A significant gender difference was also found in the largest surgical subgroup--patients who underwent coronary artery bypass grafting.

The findings suggest that the adrenal response to shock is highly variable and that relative adrenal insufficiency is more common than previously thought, the researchers explained.

--Kristin Della Volpe

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