People seem to be heeding well-reported warnings about the heat and staying healthy, officials at Lake County's hospitals said Thursday.
Only one area hospital -- Advocate Good Shepherd near Lake Barrington -- reported a significant increase in cases caused by the heat.
Between the last week's power outages and this week's oppressive heat, emergency room visits are up 20 percent at Good Shepherd, spokesman Mike Deering said.
Several patients over the last few days have come in with life-threatening heat stroke, but there haven't been any fatalities. Most were outdoor workers such as truck drivers or construction workers, Deering said.
"These people had a serious condition and most were unconscious by the time they got to us," he said. "They're hustling to work hard, but everyone needs to remember to be careful, slow down and drink plenty of fluids."
Lake County's other hospitals didn't report the same influx of cases.
"Once in a while someone will come in who's a little overheated," said Dr. Jack Franaszek, the emergency department's medical director at Northwestern Lake Forest Hospital.
Franaszek believes media reports about the current heat wave and past experiences have affected how people behave in extreme heat. People know to stay hydrated, to check on elderly neighbors or friends and to take other important precautions, he said.
As a result, Franaszek doubts the Chicago area will ever again suffer mass casualties like it did during a notorious 1995 heat wave.
Advocate Condell Medical Center in Libertyville has not seen a dramatic increase in the number of people coming in with heat-related ailments, either.
Those who have come in mainly have been people with respiratory ailments, such as asthma or emphysema, that have been aggravated by the heat, said Jody Jesse, a nurse and director of Condell's emergency department.
NorthShore University HealthSystem spokesman Jim Anthony said emergency room activity hadn't increased as of Thursday afternoon at its hospitals in Highland Park, Skokie, Glenview and Evanston.
"The numbers don't lie when we've had just one patient present with (heat-related) illness at all four of our hospitals," Anthony said.
Vista officials at the newly opened emergency center in Lindenhurst and Vista East in Waukegan have treated patients with heat-related symptoms, said Dr. Kenji Oyasu, medical director for both facilities.
Some patients knew they were ill but did not know why, Oyasu said.
"Symptoms of dehydration are very nonspecific, and we have had people coming in saying 'I'm nauseous, I'm feeling lightheaded, or I'm just not feeling well and I can't explain it,'" Oyasu said. "We run the tests and are finding out that in most of the cases they just haven't been managing their water intake and are becoming dehydrated."
Oyasu said it is important for the very young and the elderly to be on guard for heat-related maladies, as many of the people he has seen this week fall into those categories.
People who have other health concerns also need to be mindful of the impact of severe heat, Oyasu said.
• Daily Herald staff writers Tony Gordon, Kimberly Pohl, Bob Susnjara and Mick Zawislak contributed to this report.