4
    事实上，ICU患者几近半数存在发热现象。基于人们的通常见识，发热是不好的。因此，一旦体温略高，家属及医生便着手退热治疗。否则，则被认为是个烂医生。

    可是，降温的合理性在那里呢？2000年2月28日，Archieves Of Internal Medicine刊登一篇文章，题为Antipyretic Therapy：Physiologic Rationale, Diagnostic Implications, and Clinical Consequences（解热治疗：生理原理、诊断价值及临床结局），作者来自美国巴尔的摩马里兰大学医学院。

    首先，作者简述到，自远古时代起人们就开始用柳树皮的浸液来降低体温。随后，又简述了阿司匹林的研发过程。Antipyretic agents have been used to lower febrile body temperature for well over two millennia.^1-2 Ancient Assyrian, Egyptian, and Greek physicians all apparently knew of and exploited the antipyretic property of extracts of the bark of the willow (Salix alba).² However, it was not until 1763 that the Reverend Edward Stone gave the first scientific description of the clinical benefits of willow bark to the Royal Society of London.³ Less than 80 years later, Piria⁴ succeeded in preparing salicylic acid from salicin, a glycoside component of willow bark. Salicylic acid was first synthesized by Gerland⁵ in 1852, some 8 years before Kolbe and Lautemann,⁶ who are frequently credited with this accomplishment, and just a year before von Gerhardt⁷ developed acetylsalicylic acid (aspirin) during efforts to find a more palatable form of salicylate. In 1899, the Bayer Company launched the modern era of antipyretic therapy with the introduction of aspirin as the world's first commercially available antipyretic drug.¹ During this same period, acetanilide and phenacetin were derived from para-aminophenol compounds in coal tar, and pyrazolon compounds such as aminopyrine were developed.²

A little less than a century later, the marketplace is replete with drugs capable of suppressing fever. Their widespread application by primary care physicians,⁸ emergency department nurses,⁹ pharmacists,¹⁰ parents, and other caregivers^11-12 has been, at least in part, motivated by a general suspicion that fever is inherently noxious. This suspicion is reflected in the results of surveys reporting that approximately 40% of parents and other caregivers regard temperatures encountered during fever as harmful,^11-12 and that 12% of physicians believe that fever has the capacity to cause brain damage.⁸ Perhaps most indicative of the medical profession's inherent antipathy toward fever is the fact that an estimated 70% of nurses and 30% of physicians routinely use antipyretic drugs to suppress fever.^8-9

    那为何人们要降温呢?最主要的一点，人们一直认为体温的升高像预警信号一般，对身体是有害的；适当的解热将减轻此种有害反应。

Nevertheless, many clinicians believe that even the relatively modest increases in core temperature encountered during fever are deleterious to certain patients and should therefore be suppressed.

Children, primarily between ages 3 months and 5 years, are 1 such category of patients. In these children, seizures have occurred during episodes of fever at a frequency of from 2% to 5% in the United States and Western Europe^18-19 to as high as 14% in other selected countries.²⁰ Although most children have temperatures of 39.0°C or lower at the time of their seizure,²¹ many tolerate higher fevers at later dates without convulsing.²² Unfortunately, antipyretic therapy has not been shown to protect against recurrences of febrile seizure in the few controlled trials conducted thus far.²³

It has also been suggested that patients with underlying cardiovascular or pulmonary disorders might be especially susceptible to the adverse effects of fever because of the increased metabolic demands imposed by the elevated temperature.²⁴ Such demands, which peak during the chill phase, largely as a result of shivering, include increases in sympathetic tone,²⁵ oxygen consumption, respiratory minute volume, and respiratory quotient.²⁶ Although these have been proffered as prima facie justification for antipyretic therapy in patients with underlying cardiopulmonary disorders, the risk-benefit ratio of such therapy has yet to be determined.

Antipyretic therapy might also be justified, at least in theory, if fever's metabolic cost exceeded its physiologic benefit, if the treatment provided symptomatic relief without adversely affecting the course of the febrile illness, and/or if the toxicologic costs (adverse effects) of the antipyretic regimen were appreciably lower than its beneficial effects. Unfortunately, although clinicians have long argued the validity of each of these propositions as justification for antipyretic therapy, few experimental observations exist to support any of these arguments.²⁷

    说归说，理论归理论，很少有人研究体温升高对人体的作用。作者在结论部分说：

Although clinicians have used various forms of antipyretic therapy since time immemorial, there is a dearth of data concerning the benefits and relative risks of such treatments. （自远古以降，医生解热方法各异，尚缺乏有效数据，以兹验证解热疗法的利弊。）Nevertheless, several tentative conclusions regarding antipyretic therapy seem justified in light of the limited data available. It is clear, for instance, that short courses of approved doses of standard antipyretic drugs carry a low risk of toxic effects. Most of these drugs have analgesic as well as antipyretic properties. Therefore, if not otherwise contraindicated (eg, aspirin in young children because of the risk of Reye syndrome), such drugs can be used to provide symptomatic relief in patients with fever, to reduce the metabolic demands of fever in chronically debilitated patients, and possibly to prevent or alleviate fever-associated mental dysfunction in the elderly. To minimize antipyretic-induced fluctuations in temperature (and the risk of recurrent shivering and its increased metabolic demands) antipyretic agents should be administered to patients with fever at regular intervals to preclude abrupt recurrences of fever, rather than as needed for temperatures above some arbitrary level. When prescribing such medications, physicians must recognize that each carries its own risk of toxic effects, and might prolong the course of at least some infections. It should be noted further that there is no compelling evidence that a response to antipyretic medications is useful diagnostically in distinguishing serious from self-limited illnesses, nor is there evidence that such medications are effective in suppressing febrile seizures, even if given prophylactically.

In view of the capacity of external cooling measures to induce a cold pressor response,^{89, 91} it is questionable whether this form of antipyretic therapy should ever be administered to patients with fever (much less to patients in the intensive care unit, for whom it is most commonly prescribed). If external cooling is used to treat fever, care must be taken to prevent shivering because of its associated increase in oxygen consumption. Unfortunately, even if shivering is prevented, there is no guarantee that a cold pressor response will be averted. In view of indomethacin's capacity to cause coronary vasoconstriction in patients with coronary artery disease,⁹³ NSAIDs should be used with caution, if at all, to suppress fever in such patients.

    5

     发热到底是好是坏呢？答案，自然并不容易得出。

    2002年出版的一本sepsi专著The Sepsis Text 中，就对脓毒症时发热是否治疗问题进行过论述。尽管sepsis的研究更新较快，但就发热这一小点而言，人们获得的新知并不比以前更多。

    在这一章节里，作者引用了几个与发热有关的名句：

   ——Sydenham

                                              ——Hutchinson

                                                         ——Hoffmann & Dreser

其中，第一位Sydenham（西德纳姆，1624～1689年）被誉为英国的希波克拉底。他认为他认为疾病是纠正紊乱的过程，发热是机体抵抗疾病的反应。他跟希波克拉底一样，认为人体存在抵抗疾病的自然康复能力。他是一位作经验主义在医学领域的代表。主要著作有：《热病治疗法》等。http://www.sil.si.edu/digitalcollections/hst/scientific-identity/fullsize/sil14-s007-02a.jpg
    上面三句里，头两句颇为有名，也颇有争议。在流感病毒引起的发热里，也有人对此进行过争议。不妨看看去年底英国医学杂志（BMJ）上的小文章:

A/H1N1 flu pandemic

Fever as nature’s engine?

Data suggest that the use of paracetamol to reduce the body temperature and alleviate the symptoms of flu is counterproductive.^{1 2}

Infectious organisms are adapted to the temperature of the part of the body they colonise. Rhinoviruses, which infect the cooler upper airway and sinuses, grow best at 33-35ºC, so inhaling air at about 45ºC for 20 minutes significantly improves the symptoms of a common cold.³ Conversely, treating the common cold with aspirin causes a significant increase in the rate of production of the virus.⁴ Moreover, if fever is suppressed in ferrets infected with flu virus, illness is prolonged.⁵

The effect of lowering or raising body temperatures in humans with flu has not been studied, but there are good reasons to treat flu by encouraging the temperature to rise to 40ºC for at least 24 hours. The lack of such research may be due to a deep seated fever phobia stemming from pre-scientific medicine, when fever was perceived as an illness in itself. However, in the 17th century Thomas Sydenham said, "Fever is nature’s engine which she brings into the field to remove her enemy," the potential of which remains unrecognised by the public and the medical profession.

    6
    上面所提到的,貌似均像是对发热的一种辩护。事实上，我所记述的，也只是罗织材料在此，以供查阅方便。而对某些疾患而言，发热或许是好的。这并不总意味着，发热或升高体温，就是一件大好事。尤其是，当专业的知识被包装套用时。

    马悦凌的《温度决定生老病死》正是一例。曾经，我在《南都周刊》上批驳过此类养生书的种种不靠谱之处。接着这一次写发热，我大致浏览了当当网上的连载。主要的感觉有以下几个：

    其一，养生书要忽悠人，必得标题如雷贯耳，一雷惊人。对一本养生书而言，最重要的是什么？答案是书名。书名就像一个巴掌，啪的一声拍在大家脸上，直接技术性击倒。换句话说，标题就是态度。只有信标题，才能得永生。其次重要的，是文采斐然的前言。比如这本书的前言，作者名之曰《我所理解的温度》。换句话说，前言像是一本养生书的理论建构，它是一本养生书赖以写作和维持的基础。一篇语言劲道，深入浅出的前言，能忽悠到大部分人。再其次的，是目录。目录必须标题明确，直击人心。只要一看到目录各条目，诸位看官便常有相见恨晚之感。

   其二，养生书要忽悠人，必须有一定的理论深度。必须上知天文，下懂地理人事。要善于将西医的理论及成果做壳，然后冠之以中医或“邪术”的养生思想，这样才能既有深度，又能接近群众。很多不靠谱的养生书，常会将正常的概念偷梁换柱，片面夸大人体正常生理指标的健康意涵。随后，借助一个自创的养生理念，来加以无限制阐释。

   其三，养生书要忽悠人，必须用通俗易懂的方式。要多用比喻，要把人体比喻成春夏秋冬，要把人体活动用最简单常见的事物来做比，如种地、施肥等。这样才平易近人，有助一般读者理解和接受。毕竟，大家喜欢的是大白话。

    上述几句，也多使用其他各种养生系列书。仔细搜索的话，你能找到N种《XX决定生老病死》的话语。有意思的是，目前倒是没有人写《基因决定生老病死》。我的感觉是，其一、对各路养生学大师而言，基因这玩意有点超乎专业之外，他们还是喜欢在简单常见的概念上忽悠。其二、基因这玩意，每个人的个体太特异，养生学大师们并不好操作（纵）。换句话说，尽管基因在某种程度上比温度，更能决定人体的生老病死，但却无益于宣扬养生学大师的理念。因此，谁要是写《基因决定生老病死》等于拆自家门台。他们才不会做这样的事！

    事实上，养生靠什么呢？要我说，最简单的一点，就是去伪存真的听妈妈的话。养成一个好习惯，好好吃饭不挑食，好好睡觉不折腾，好好心情不纠结，好好习惯讲卫生....做好最简单常见的几条，就能保准你活的有滋有味。

    可是，大家都喜欢折腾自己，活的一点都不健康！改天，养生学大师们倒是可以写本绝对有意思的书，叫《折腾决定生老病死》。随后再来个姊妹配——《不折腾的人生》。当然，还可以反其道而行之，出一本《折腾无罪：健康启示录》。腰封上写道，“人生就是一场折腾。我不是在折腾，就是在前往折腾的路上。”