急危重症SCI述评文章撰写|很多讲究

急危重症SCI述评文章撰写｜很多讲究

受邀写述评，恭喜您。那么问题来了，述评怎么写？一般的思路是先介绍背景，把自己想要陈述的观点先铺垫好；当你觉得铺垫内容已经准备得足够充分的时候，第二步便是引出述评来源，通常是受邀评论article，这一部分是文章的核心内容，不只是简要介绍article的主要结果，更重要的是对结果进行透彻分析，这个分析过程是高度凝练的、没有废话、站在更全面、更高的层面的去思考现象背后的本质问题。一个好的述评一定是客观评价，而不是一边倒的褒扬；一篇优秀的述评不是空洞的谈理论，而是要与现象完美的融合，能够展现非常流畅的逻辑思维过程。当然，这首先的前提是你要全方位阅读article，包括它的设计、统计、结果、讨论、充分挖掘可以探讨的要点，摸索原作者的研究意图。然后要查阅所有重要相关的文献，整理思路。

下文便是匹兹堡大学重症监护医学科John教授近期在JAMA杂志上发表的述评文章：危重患者血管内晶体液毒性评估。评论的是Young等此前在JAMA杂志上发表的SPLIT研究（比较缓冲晶体液与生理盐水对危重患者急性肾损伤的影响）。为了引出Young的研究，John花了四个段落，16个引文作了很好的铺垫，首先从与口服比较，静脉输液相对危险；然后提到静脉输液的用途以及基本的使用特点，此后根据最经典的临床研究引出危重患者静脉输液到底坏在哪里；之后介绍生理盐水的缺点在哪里？因为高氯的危害性，从而引出低氯晶体液。这些就是为young的研究做了铺垫，使用的方法包括抽象到具体、整体到个体。

Intravenous administration of a specific fluid may have very

different effects compared with enteral administration of the

same fluid. For example, pure water is well tolerated when given

orally, but is highly injurious (leading to hemolysis) when

administered intravenously. Intravenous fluids are the most

common intervention prescribed for hospitalized patients and

may be administered for multiple reasons, such as for

rehydration (as an alternative to the enteral route), as a vehicle or

carrier for medication delivery, and to produce direct physiologic

effects on cardiac output and electrolyte concentrations (as

drugs). There are important differences in the composition,

volume, and rate of administration of fluids for these different

uses.

Over the last 25 years, the safety and efficacy of intravenous

fluids have been vigorously debated. First, the composition of

lactated Ringer solution was changed from a racemic mixture of

lactate ions to pure

L-lactate when high concentrations of the

D-isomer were found to be toxic, including cardiac and neural

toxicity.1 Next, the combination of several small studies

examining the use of albumin for fluid resuscitation suggested

an association with decreased survival.2 Even though a

subsequent large trial showed no overall mortality difference

between albumin vs saline for fluid resuscitation of patients in

the intensive care unit (ICU), there was evidence of toxicity in 1

predefined subgroup.3Subsequent analysis including detailed

follow-up provided additional evidence that a 4% albumin

solution was harmful for patients with increased intracranial

pressure, probably related to its hypotonicity and the effect on

intracranial pressure.4 More recently, the use of hydroxyethyl

starch was found to have an adverse effect on survival among

patients with sepsis, apparently related to its effect on acute

kidney injury (AKI).5 A subsequent larger trial showed no

significant difference between hydroxyethyl starch vs saline

administration and mortality, and also demonstrated that

hydroxyethyl starch was associated with a reduction in AKI but a

small increase in the use of dialysis.6Importantly, trials showing

harm used much larger volumes of starch and studied higher-risk

patients.7 As a result, most experts now accept that hydroxyethyl

starch is at least mildly nephrotoxic, although disagreement

exists as to whether the solution still has a role in the

management of some patients.

Isotonic 0.9% sodium chloride (saline) solution is the most

commonly used intravenous fluid in much of the world, and

especially in North America.8The toxic potential of sodium

chloride solutions was known at least as early as the late 19th

century and was described by Cushing9 among others. Although

the sodium concentration of isotonic saline is only slightly higher

than that of plasma, the higher than physiologic chloride

concentration can lead to hyperchloremia and acidosis if isotonic

saline is administered fast enough, and in large enough

volumes.10 Bolus administration of either isotonic saline or

albumin in saline was found to increase short-term mortality in

children with sepsis in Africa.11 Although the mechanism of this

toxicity is unclear, increased deaths appeared to be mainly

related to late cardiovascular collapse—a known consequence of

experimental hyperchloremic metabolic acidosis in septic

animals.12

Numerous observational studies13- 15 and a sequential

period trial16 have suggested a signal of potential harm when

saline administration was compared with administration of fluids

with more physiologic chloride concentrations, although the

kinds of adverse outcomes have varied. Some studies have

shown increased AKI or dialysis,13,16 whereas other reports have

shown increased hospital mortality without an effect on AKI.14

This heterogeneity of effect is important because it demonstrates

2 essential aspects about toxicity—that toxicity is dose

dependent and that the manifestation of toxicity depends on the

susceptibility of the population exposed. A high “dose” of a

low-toxicity substance will cause harm in a susceptible patient,

whereas a low dose of a highly toxic substance may be

undetectable in a low-risk patient. Put more simply, if there is a

hazard with saline administration, then healthier patients who

receive small doses will deal with the hazard better than sicker

patients who receive large doses.

第二部分是核心内容，首先引出述评引文来源，第一段必须是客观描述引文，包括研究性质、干预方法、样本量、分组、研究结果。

In this issue of

JAMA, Young and colleagues17 report the 0.9%

Saline vs Plasma-Lyte 148 for ICU fluid Therapy (SPLIT) trial, a

multicenter study comparing 0.9% saline with a buffered

electrolyte solution for fluid therapy among 2278 patients who

were receiving treatment in 4 ICUs in New Zealand and required

crystalloid fluid therapy. The indications for fluid were not

specified, but presumably included both volume replacement as

well as fluid resuscitation and other indications. The overall

exposure to study fluids was small (a median of only 2 L) during

the ICU stay, and most of the fluid administration occurred

during the first 24 hours. The population was (at most) moderate

risk (mean Acute Physiology and Chronic Health Evaluation

[APACHE] II score, 14) and predominantly included postoperative

patients. Overall, development of AKI within 90 days of

enrollment (the primary outcome) occurred in only

approximately 9%, and rates of renal replacement therapy (RRT)

and in-hospital mortality (key secondary outcomes) were

approximately 3% and 8%, respectively, with no significant

differences between the buffered crystalloid group and the saline

group (AKI, 9.6% for buffered crystalloid vs 9.2% for saline; RRT,

3.3% for buffered crystalloid vs 3.4% for saline; mortality, 7.6%

for buffered crystalloid vs 8.6% for saline).

介绍完后一定首先要表扬一下，研究有什么指导、借鉴、参考意义。禁忌一边倒的批判。

The study was well conducted with excellent adherence to

study protocol and near-complete follow-up, and the results

have high face validity. The authors conclude that fluid choice did

not alter the risk of AKI and that “further large randomized

clinical trials are needed to assess efficacy in higher-risk

populations and to measure clinical outcomes such as

mortality.”17 This trial has set the stage for future studies, which

should be guided both by the success of the trial in its protocol

adherence and pragmatic elegance as well as by its limitations.

一般情况下，如果研究暴露的问题比较大，但这些问题与研究本身无关，那么可以大胆放肆的批判，特别是需要详细解读，避免读者对文章结果进行片面性放大；如果研究牵涉问题不多，那么可以围绕结果放肆的进行表扬性评述。

However, some important points merit discussion. First, it is

unclear how much physiologic separation may have occurred

between the 2 fluid administration groups. The authors did not

report serum chloride data, which may have allowed an estimate

of whether there was sufficient difference between the groups to

permit a plausible effect on clinical outcomes. Second, the total

exposure to these 2 fluids was minimal, approximately 2 L during

the entire ICU stay. It is unlikely that this amount of fluid volume

could have demonstrated a plausible hazard, and not in the study

population that was at low risk for AKI or other adverse effects.

Third, if the trial had been designed to test the efficacy of fluids

on renal function, then the authors would have had to measure

renal function or injury in a more granular fashion, perhaps

including biomarkers or imaging studies. Prior studies in

animals18 or healthy volunteers19 have shown important effects

of fluids on the kidney. If the investigators had used the

techniques used by Chowdhury et al,19 then they would most

likely have demonstrated similar changes in renal blood flow and

function, but these do not necessarily lead to an increase in

moderate-severe AKI, as measured by changes in serum

creatinine. In the healthy kidney, substantial functional reserve

must be exhausted before serum creatinine increases.

Another concern is whether the trial reported by Young et al

is an effectiveness trial. The effectiveness of fluids for treating or

preventing AKI would require the presence of (or risk for) fluid

responsive AKI, and clinicians would need to understand that

they were using the fluid for this indication. Instead, the SPLIT

trial enrolled patients who received fluid for a variety of

indications and the effectiveness for each indication was not

assessed. Rather, adverse events were measured. Thus, the SPLIT

trial, like the CHEST6 and SAFE trials,3 were actually toxicity

studies, or at best were studies that accepted a broad assessment

of effectiveness using mortality as a surrogate outcome. The

surrogacy of the mortality end point is clear because few, if any,

patients who are critically ill die for lack of 2 L of crystalloid.

This fundamental premise that large pragmatic studies can

be used to assess the effectiveness of fluids on outcomes such as

AKI, requirement for dialysis, and mortality should be carefully

considered when the intervention is not being used specifically

for these purposes. Drugs such as 0.9% saline or other electrolyte

solutions might result in differences in these outcomes, but it will

be as a result of differences in toxicity, not efficacy, and studies

should be designed accordingly. In particular, such studies need

to deliver a plausible dose of fluids to a population at sufficient

risk for adverse outcomes to uncover the hazard, if one exists. If

there is a hazard with one or another of these fluids, then it will

be important to discover and quantify that risk, however small,

because of the sheer enormity of the exposed population that

receive intravenous fluids. This hazard will not be unmasked by

treating healthier patients with small doses of fluids, but rather

by treating sicker patients with larger fluid volumes.

第三部分为总结。形式可以是全文总结，也可以是逻辑形式上的直接结尾。

In the meantime, the results of the trial by Young et al

provide reassurance that neither 0.9% saline nor a low-chloride

electrolyte solution appears to be particularly hazardous when

the total dose used in patients at low to moderate risk is about 2

L. This is an important contribution to the care of patients in the

ICU. However, the large body of “circumstantial” evidence that

points to a harm signal for saline—with scant, if any, evidence of

comparative benefit—should behoove intensivists and other

clinicians to proceed with caution when ordering intravenous

fluids.

AUTHOR INFORMATION

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Editorials represent the opinions of the authors and

JAMA

and not those of the American Medical Association.

Corresponding Author: John A. Kellum, MD, Center for

Critical Care Nephrology, 604 Scaife Hall, 3550 Terrace St,

Pittsburgh,PA15261(*****************).

Published Online: October 7, 2015.

doi:10.1001/jama.2015.12390.