Croup — The Bark Is Worse Than the Bite
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《新英格兰医药杂志》
It is a cliché of primary care pediatrics: on call in the winter, you find yourself on the telephone with a worried parent who is anxiously trying to describe a baby's symptoms — and then, in the background, you hear the barking. I regularly joke with other pediatricians about the things we're asked to diagnose over the phone ("Could you just hold the receiver right up to the rash?"), but croup is an easy long-distance diagnosis. Parents call at night because croup gets worse at night. The barking cough can be terrifying to a parent who hasn't heard it before, and of course, the respiratory distress can be very real. So you ask whether the baby's chest is sucking in with every breath, and you have the parent listen for the strange, tortured whistle of stridor. My paradigm for over-the-phone advice has always been that children with respiratory distress go to the emergency room, and other children into a steamy bathroom to see whether the moisture helps.
Nowadays, the term croup denotes an anatomical location, a cause, and a pathologic entity — laryngotracheobronchitis, inflammation of the upper airway below the glottis, caused by a viral infection. But that meaning has changed over time, reflecting the shifting epidemiology of infections and immunizations. "Croup" once suggested a wider spectrum of infections, viral and bacterial, much as "pneumonia" still does today. "Diphtheritic croup" was a highly serious infection in young children, associated with a mortality rate of about 25 percent. And of course, croup of any microbiologic cause that brought serious respiratory distress was potentially fatal in the era before children could be intubated and ventilated — procedures that are still performed in the small percentage of children with viral croup whose airway compromise is most severe.
In the classic 1908 girls' book Anne of Green Gables (by Lucy Maud Montgomery), the plucky red-headed orphan heroine is summoned by her friend, whose baby sister is seriously ill with croup, one January night on Prince Edward Island. The 11-year-old Anne rushes out to the rescue, pausing only to grab a bottle of ipecac. When the doctor finally arrives, the sick child is better, and Anne explains, "I was awfully near giving up in despair. . . . She got worse and worse. . . . I actually thought she was going to choke to death. I gave her every drop of ipecac in that bottle, and when the last dose went down I said to myself . . . `this is the last lingering hope and I fear 'tis a vain one.' But in about three minutes she coughed up the phlegm and began to get better right away. You must just imagine my relief, doctor, because I can't express it in words." In fact, ipecac remained part of the armamentarium used for croup well into the 20th century. One physician described to me watching for the appearance of the mucous plug after administering ipecac to a baby with croup; the plug would be a perfect cast of the child's airway. I imagine a plug disconcertingly thin, a physiological lost-wax-method image of the "steeple sign" we look for on neck films (see Figure), which results from edema and subglottic narrowing.
Figure. The "Steeple Sign" Found in Croup.
Radiograph courtesy of Sudha Anupindi, M.D.
But respiratory distress can usually be managed now, and diphtherial infection is no longer on the list of my late-night worries. Today, when you hear that classic seal-like cough, you think about a viral infection, self-limited and usually fairly mild. Still, as Bjornson et al. point out in this issue of the Journal (pages 1306–1313), even mild croup can be a frightening disease for a parent to watch — a small child helplessly wracked by a strange, harsh cough that gets worse into the night, keeping both child and parent awake. For years, part of my algorithm in dealing with mild croup, if the child was not in respiratory distress, was to warn the parents that medicine had nothing to offer. If they went to the emergency room, the trip itself might prove therapeutic — in some children, croup improves on exposure to cold outside air — but there would be no medical intervention that would ease the child's night or hasten resolution.
When you're taking care of a small, sick child, though, you feel the need to do something. I couldn't just advise parents to stand by and listen to the barking. And I think that one reason the steam-up-the-bathroom advice came so easily to me — and was so gratefully received by parents — was that it was a specific and slightly challenging assignment. Sometimes I would hang up the phone and picture the mother I had just been talking to — sitting on a closed toilet seat in a small bathroom with the shower running full and hot, holding her baby, both of them taking comforting gasps of the steamy air. Unfortunately, though this hydration and humidification therapy carries the weight of decades of practice, its efficacy has not been well supported by objective studies; when I recommend it, I am acting out of some non–evidence-based hope that it may temporarily ease the coughing — or perhaps the congestion — and because it feels better to do something.
Corticosteroids have changed our management of croup over the past 15 years. We know that they make a difference for children with respiratory distress and severe disease. But there is certainly a danger that the same need to do something, to have some therapy to offer, will drive us to generalize — to offer the therapy to any child with even mild illness, without necessarily knowing whether it confers any benefit. The study by Bjornson et al. addresses this question and quantifies the "small but important" gains that can add up to a major difference in how a young child's illness is experienced by the child and the family. A case of croup that is seen by the doctor as reassuringly mild can nevertheless mean sleepless nights, anxiety, and misery for the whole family. That's still no reason to offer an intervention that doesn't actually help, but it's an excellent reason to offer one that shortens the illness and helps everyone get a better night's sleep.
Source Information
From the Boston University School of Medicine and Boston Medical Center, Boston.(Perri Klass, M.D.)
Nowadays, the term croup denotes an anatomical location, a cause, and a pathologic entity — laryngotracheobronchitis, inflammation of the upper airway below the glottis, caused by a viral infection. But that meaning has changed over time, reflecting the shifting epidemiology of infections and immunizations. "Croup" once suggested a wider spectrum of infections, viral and bacterial, much as "pneumonia" still does today. "Diphtheritic croup" was a highly serious infection in young children, associated with a mortality rate of about 25 percent. And of course, croup of any microbiologic cause that brought serious respiratory distress was potentially fatal in the era before children could be intubated and ventilated — procedures that are still performed in the small percentage of children with viral croup whose airway compromise is most severe.
In the classic 1908 girls' book Anne of Green Gables (by Lucy Maud Montgomery), the plucky red-headed orphan heroine is summoned by her friend, whose baby sister is seriously ill with croup, one January night on Prince Edward Island. The 11-year-old Anne rushes out to the rescue, pausing only to grab a bottle of ipecac. When the doctor finally arrives, the sick child is better, and Anne explains, "I was awfully near giving up in despair. . . . She got worse and worse. . . . I actually thought she was going to choke to death. I gave her every drop of ipecac in that bottle, and when the last dose went down I said to myself . . . `this is the last lingering hope and I fear 'tis a vain one.' But in about three minutes she coughed up the phlegm and began to get better right away. You must just imagine my relief, doctor, because I can't express it in words." In fact, ipecac remained part of the armamentarium used for croup well into the 20th century. One physician described to me watching for the appearance of the mucous plug after administering ipecac to a baby with croup; the plug would be a perfect cast of the child's airway. I imagine a plug disconcertingly thin, a physiological lost-wax-method image of the "steeple sign" we look for on neck films (see Figure), which results from edema and subglottic narrowing.
Figure. The "Steeple Sign" Found in Croup.
Radiograph courtesy of Sudha Anupindi, M.D.
But respiratory distress can usually be managed now, and diphtherial infection is no longer on the list of my late-night worries. Today, when you hear that classic seal-like cough, you think about a viral infection, self-limited and usually fairly mild. Still, as Bjornson et al. point out in this issue of the Journal (pages 1306–1313), even mild croup can be a frightening disease for a parent to watch — a small child helplessly wracked by a strange, harsh cough that gets worse into the night, keeping both child and parent awake. For years, part of my algorithm in dealing with mild croup, if the child was not in respiratory distress, was to warn the parents that medicine had nothing to offer. If they went to the emergency room, the trip itself might prove therapeutic — in some children, croup improves on exposure to cold outside air — but there would be no medical intervention that would ease the child's night or hasten resolution.
When you're taking care of a small, sick child, though, you feel the need to do something. I couldn't just advise parents to stand by and listen to the barking. And I think that one reason the steam-up-the-bathroom advice came so easily to me — and was so gratefully received by parents — was that it was a specific and slightly challenging assignment. Sometimes I would hang up the phone and picture the mother I had just been talking to — sitting on a closed toilet seat in a small bathroom with the shower running full and hot, holding her baby, both of them taking comforting gasps of the steamy air. Unfortunately, though this hydration and humidification therapy carries the weight of decades of practice, its efficacy has not been well supported by objective studies; when I recommend it, I am acting out of some non–evidence-based hope that it may temporarily ease the coughing — or perhaps the congestion — and because it feels better to do something.
Corticosteroids have changed our management of croup over the past 15 years. We know that they make a difference for children with respiratory distress and severe disease. But there is certainly a danger that the same need to do something, to have some therapy to offer, will drive us to generalize — to offer the therapy to any child with even mild illness, without necessarily knowing whether it confers any benefit. The study by Bjornson et al. addresses this question and quantifies the "small but important" gains that can add up to a major difference in how a young child's illness is experienced by the child and the family. A case of croup that is seen by the doctor as reassuringly mild can nevertheless mean sleepless nights, anxiety, and misery for the whole family. That's still no reason to offer an intervention that doesn't actually help, but it's an excellent reason to offer one that shortens the illness and helps everyone get a better night's sleep.
Source Information
From the Boston University School of Medicine and Boston Medical Center, Boston.(Perri Klass, M.D.)