When I'm on the night shift, all the department heads can't sleep.

The automatic door at the emergency room entrance had only slid halfway open when the smell of rainwater wafted in first, followed by the smell of barbecue fumes clinging to my clothes.

The flatbed cart wheel bumped against the threshold. Night shift nurse Xiao Zheng held onto the bed railing with one hand and reached for the child in the father's arms with the other. A security guard stood nearby, his uniform cuff stained with a little vomit.

The child, about seven or eight years old, had cumin powder smeared on the front of his short-sleeved shirt and mud stains on his trouser legs after the rain. He slumped limply in his father's arms, his lips grayish, as if they had been frozen.

"Doctor, doctor, please take a look! He was talking just now, but he suddenly stopped talking on the way here."

The man still clutched his car keys in his hand, the key teeth leaving several red marks on his palm. His shoelaces were untied, and he ran alongside the flatbed cart, his heels barely touching the top of his shoes.

Sun Zhiqiang had already arrived at the door.

"Lay him flat on the cart, head to one side. Xiao Zheng, bring the suction device over, connect the oxygen."

Lin Ye supported the child's shoulders and turned him slightly to the side. A small amount of vomit dripped from the corner of his mouth again, and Xiao Zheng immediately handed him the suction tube.

"Little friend, can you hear me?"

The child did not open his eyes, only making a few muffled breaths from his throat.

Sun Zhiqiang touched the child's neck with the back of his hand, then looked at Lin Ye.

"Report the situation."

Lin Ye pressed his fingertips on the child's pulse.

My heart is beating fast.

The skin wasn't hot.

But that grayish-purple color didn't seem like it had simply vomited water.

"Poor consciousness, weak response to calls. Just vomited, first check for aspiration. Rapid pulse, gray lips, check blood sugar, blood pressure, and blood oxygen, connect to monitoring."

"Put the monitor on first, and test the blood sugar."

As soon as Sun Zhiqiang finished speaking, the flatbed cart was pushed into the entrance of the red zone.

On Song Guangfu's side, the cardiologist on duty was still by his bedside completing the medical orders. Hearing the noise, he only looked up briefly before quickly looking down again to check the chest pain medication procedure.

"I'll take care of bed four, you guys go ahead with the one by the door."

Nurse Zhao wasn't too far from the red zone; the cardiology doctor on duty was holding down the medical record folder for Song Guangfu. She pulled a spare mask from the top of the treatment cart, shoved it into Xiao Zheng's hand as he passed by, and waved to the child's father.

"Father, stand at the foot of the bed, don't lie on top of the baby. You're blocking the doctor's hands."

The man stopped abruptly, pressed himself against the foot of the bed, and his voice was strained.

"Did he eat something bad? Several people at the night market threw up. He only ate two chicken wings, a cup of ice jelly, and some cold beef salad. I told him I shouldn't have let him eat that."

At the triage desk, the nurse was still following up on the earlier forecast.

"Is there a charcoal stove nearby? Is the generator inside the shed? Is the shed sealed off?"

Just as Lin Ye was about to ask what he had eaten, a light suddenly appeared at the edge of his field of vision.

A light blue notification popped up at the edge of his field of vision.

[Emergency Room Warning: Increased risk of acute methemoglobinemia.]

[Possible source: Nitrite-related food poisoning.]

[Common misdiagnosis points: common food poisoning, pulmonary hypoxia, asthma attack.]

[Key abnormality: pronounced cyanosis, blood oxygen levels do not increase after oxygen therapy, and the blood oxygen partial pressure may not be low.]

Lin Ye tightened his grip on the bed railing, his gaze shifting from the oxygen mask to the blood collection tubes on the treatment cart.

The 120 emergency call just now instructed the triage team to prioritize the shed, charcoal fire, and generator.

But the color of the child in front of me is wrong.

We have to check the blood first.

He didn't look at anyone else, but turned directly to the child's father.

"Put the chicken wings aside for now. Which stall sold the cold beef salad? When did you eat it? Who else at the table ate it? Did anyone else experience purplish discoloration, dizziness, or chest tightness?"

The man was taken aback.

"The cold beef salad was cut by the braised food stall next door, and everyone took some. He was craving it, so he ate a couple more bites."

"Did those people who vomit eat from the same plate?"

"I ate it," the man answered quickly, then panicked, "Doctor, is the meat spoiled?"

Xiao Zheng handed over the blood glucose meter.

"Blood sugar is 6.1."

Another nurse wrapped the cuff around her arm.

"Blood pressure 92/58, heart rate 132."

The moment the monitoring clip was attached to the child's finger, the numbers on the screen jumped twice.

Eighty-six.

The oxygen mask is already on, and the oxygen flow rate is set high.

The numbers didn't change much.

Xiao Zheng stared intently at the screen, and Sun Zhiqiang's gaze also lingered on it.

The man looked over and his face turned pale.

"Why aren't we going up yet? Didn't we already start using oxygen?"

Sun Zhiqiang saw it too.

"Listen to your lungs once."

Lin Ye placed the stethoscope against the child's chest and listened to both sides. The breath sounds were not clean, but there were no obvious wheezing or wet rales.

"The color of the lungs cannot be explained by sound alone."

He had barely finished speaking when the blood-drawing needle was already in Xiao Zheng's vein.

The blood returned to the syringe very slowly.

The color is wrong too.

It's not bright red.

It wasn't the dark red color seen during shock.

The blood, brownish in color, settled in the syringe, like diluted soy sauce.

Xiao Zheng paused for half a second.

"Teacher Sun, the color of this blood is wrong."

Sun Zhiqiang reached out and took the blood collection tube, glanced at it, and his face darkened.

"For blood gas analysis, check the co-oxygenation module, including methemoglobin and carboxyhemoglobin. Also check electrolytes and lactate. Call both pediatric and second-line specialists, and have the pharmacy send methylene blue to the red zone in advance. Estimate the weight first, and ask about the patient's history of G6PD deficiency and allergies. Whether or not to wait for the results and specialist evaluation is another matter."

He then looked at Lin Ye.

"Keep asking about food."

Lin Ye nodded and placed the record paper on top of the medical record folder.

"Who ordered that plate of cold beef salad? Besides your son, were there any elderly people or children eating it?"

The man's hands were shaking so badly that he almost dropped his phone.

"My wife ate some too. She threw up in the car and didn't get out. My mom ate a bite, but she said she felt dizzy and sat by the door."

Upon hearing this, Nurse Zhao's anger flared up immediately.

"Why didn't you say so earlier when you were already at the door?"

The man flinched at the shout.

"I...I brought the baby in first."

"Security, there are still elderly people and a mother at the entrance. Don't let them leave on their own." Nurse Zhao shouted as she handed out another oxygen mask. "Those with purple lips, chest tightness, and dizziness, bring them this way first."

Chaos broke out again at the emergency room entrance.

The first private car door was still open when a woman in the back seat was clutching her chest and bending over to vomit, while an old lady next to her was holding onto the car door, her lips also having an abnormal grayish-blue tinge.

The triage nurse called out through the door.

"Teacher Sun, there are three more outside! They all say that two of them had cold beef salad from the braised food stall, and their lips looked off!"

Sun Zhiqiang raised his hand and pointed to the outside of the observation area.

"Don't crowd at the entrance to the red zone. Those who have eaten cold beef salad, braised dishes, or pickled vegetables, stand on the left. Those who have only eaten barbecue and haven't turned purple yet, go to the right first. Don't miss your wristband. Those who have turned purple, have chest tightness, are unsteady, or are children or elderly, go forward first."

Ma Hao had just returned from the imaging department, carrying the CT scan bags of five fracture patients under his arm. He was about to ask where to put the scans when Nurse Zhao glanced at him.

"Don't ask about your feet yet. Clear out those chairs; those from the night market can sit there first."

Ma Hao glanced at the children in the red zone, then at the line of people being helped in through the door, and swallowed back the joke he was about to make.

"OK."

He placed the CT scan bag on the nurses' station table and turned to move a chair.

The child's father was still staring at the tube of brown blood.

"Doctor, why is the blood this color?"

Lin Ye swallowed back the words that were about to come out and looked at the blood gas analyzer first.

The blood gas analyzer then ejected a strip of paper.

Xiao Zheng tore it off, and his fingertip was burned by the edge of the paper.

She glanced down at it, and before finishing reading it, handed the paper to Sun Zhiqiang.

"Teacher Sun."

Sun Zhiqiang took it.

The oxygen partial pressure on the note didn't look low.

But the numbers on the next line made Sun Zhiqiang pause in his folding of the paper.

Methemoglobin is 34.2 percent.

Sun Zhiqiang folded the note, making a shorter sound than before.

"Pediatrics department, urge them. Pharmacy, send methylene blue to the red zone. Don't leave the phone until the second-line emergency team arrives."

The child's father stared at the corner of the paper that Sun Zhiqiang had folded, and his voice went hoarse.

"Doctor, is his lungs damaged, or did he eat something bad?"

Sun Zhiqiang didn't rush to explain, but handed the note to Lin Ye to complete the record.

Lin Ye pressed the bloody note onto the medical record folder and looked up at the door.

Behind the first car with three people, two more private cars stopped at the emergency room entrance.

As soon as the car door opened, the security guard took two unopened disposable food containers and placed them next to the nurses' station, waiting for someone to verify which stall they came from. A whiff of the mixed smell of braised food and rainwater drifted in as the automatic door opened and closed.

Lin Ye has not yet answered the child's father.

Because a new phone call has already started ringing at the triage desk.

"Teacher Sun, the ambulance service said that there were other people at the scene with takeout containers from the same stall, but they have already gone home."