Al's Morning Meeting

Late afternoon may be the least desirable time to have surgery, according to a study that finds certain adverse effects are more common after 3 p.m.

In a review of more than 90,000 surgeries performed at their medical center, Duke University researchers found that negative effects related to anesthesia -- most often pain or nausea -- were most common after late-afternoon procedures.

For example, a patient's odds of suffering postoperative nausea and vomiting, wound infection or some other "harm" were three times higher if the surgery began at 3 p.m. versus 8 a.m. -- though few patients had such problems at either time.

Along with postoperative nausea, inadequate management of patients' pain during and after surgery was the most common problem reported.

According to the study authors, there are a number of potential reasons for the late-afternoon slump, including doctors' late-day fatigue and hospital shift rotations. It's also possible that people are more susceptible to pain or nausea late in the day -- perhaps from lack of food all day or the stress of waiting to go under the knife.

"We believe that identifying the specific periods when problems are most likely to occur is an important step in the overall process of making surgery safer and ensuring that patients have a good experience," lead researcher Dr. Melanie Wright said in a statement.

She and her colleagues at the Durham, North Carolina, medical center report their findings in the journal Quality & Safety in Health Care.

Here are some details of the study from Duke:
For their analysis, the researchers drew on a database of all of the 90,159 surgeries performed at Duke Hospital over a four-year period beginning in 2000. Maintained by the Department of Anesthesiology, the database contains a record of each surgical patient's course of treatment, including any adverse events experienced, from hospital admission to discharge.

Wright's team divided all reported problems into one of three categories: "error," "harm" and "other adverse events."

The researchers identified 31 instances of error. These involved problems related to inserting tubes into patients' throats to maintain respiration and by improper dosing of patients with anesthetic agents.

They found 667 instances of harm, which included such events as prolonged sedation, wound infection and postoperative nausea and vomiting. Postoperative nausea and vomiting accounted for 35 percent of the harm events.

They assigned 1,995 events to the "other" category. These events included potentially dangerous changes in blood pressure and operating room equipment problems. About half these events were problems related to adequate management of patients' pain through anesthetic techniques and pain medication during surgery and immediately afterward.

The team then matched each adverse event with the time the patient's surgery began and conducted statistical analyses to identify differences in the rates of events over various times of day.

"We found that adverse events were most common for operations starting between 3 p.m. and 4 p.m.," Wright said. "Furthermore, the predicted probability of an adverse event in the "other" category increased from a low of 1 percent at 9 a.m. to a high of 4.2 percent at 4 p.m."

Wright said that many factors, involving both patients and hospitals, may contribute to increased rates of adverse events late in the afternoon. For example, patients may be more susceptible to either pain or post operative nausea and vomiting in the late afternoon. We don't know if issues such as not having eaten all day or spending a stressful day waiting in the hospital may have an influence on this, Wright said.

Late afternoon also is a time when changes in the teams that administer anesthesia during surgery coincide with natural circadian rhythm lows, Wright said. The circadian rhythm serves as the body's internal clock that regulates sleep, brain wave activity and other bodily functions. Circadian lows occurring around 3 p.m. to 5 p.m. and again at 3 a.m. to 5 a.m. may affect human performance of complex tasks such as those required in anesthesia care. Changes in anesthesia care teams usually occur around 7 am and again between 4 pm and 6 pm. End of day fatigue, a circadian low point, and changes in care team are all occurring around 3 pm to 6 pm and may be interacting in a way that affects patient care, she said.

Armadillo expansion into the United States appears to be limited primarily by temperature and rainfall. Armadillos have very little body fat, and are not good at conserving heat. Long periods of extremely cold weather are dangerous, especially to younger animals. Armadillos cannot establish stable colonies if the average January temperature is below -2°C (28°F). They also require a constant source of water. Estimates indicate that armadillos can survive in areas that receive at least 38 cm (15 inches) of precipitation annually. Comparing this information with annual weather and rainfall data for the United States, Taulman and Robbins generated a potential range map for the nine-banded armadillo. They estimate that the nine-banded armadillo could establish stable populations from Nebraska to New York, and northeast to Cape Cod. Although physiological barriers prevent the armadillo from moving farther west on its own, human introductions (accidental or otherwise) could establish populations in parts of Arizona, Colorado and New Mexico. Animals released on the west coast could range from California to Washington and into parts of Canada. Regions of eastern Washington and Oregon, and part of northwest Idaho could also support armadillo populations. The published range of the armadillo in 1997 suggested that only about half of the potential armadillo habitat is currently colonized by the nine-banded armadillo. The map below illustrates the current range of the nine-banded armadillo (as of 1995), as well as the estimated potential future range.

Several panel members have favored dividing planets into categories: terrestrial planets (Mercury, Venus, Earth, Mars), giant planets (Jupiter, Saturn, Uranus, Neptune) and a third class that would include Pluto.

"We'll call them dwarf planets or something," says Iwan Williams, an astronomer at the University of London who favors the idea and also served on the panel.

Sources say the panel's new definition for planets would, in fact, create a third category embracing Pluto.

It's unclear what astronomers will make of the new definition or how they will vote on it. Observers say the definition will have to be concise and unambiguous. What is too small to be a dwarf planet? Do moons count? What about round comets?

Some panel members say they favor counting any object which is large enough that its gravity has made it round. If the object is spinning, a small bulge would be tolerated. "We're talking about no more than four or five new planets," says Iwan Williams.

Small potato-shaped asteroids wouldn't make the cut. But Ceres, a big, round asteroid between Mars and Jupiter, might qualify.