Econstudentlog

Handbook of critical care (II)

I finished the book. It was hard to rate, in part because I as mentioned in the first post am not exactly part of the main target audience. However I think the book is reasonably well written and it’s certainly not the authors’ fault that I couldn’t always figure out exactly what was going on because I’m an ignorant fool (compared to most people who’ll read this). I ended up giving it four stars.

I covered the first chapters in my first post about the book, but I’ll not cover the rest of the book in as much detail as I did the first part. Topics covered in the remaining chapters were acute renal failure, neurological emergencies, the endocrine system, gastrointestinal disorders, infection and inflammation, hematologic emergencies, nutritional support, physical injury (including things like burns and electrical injuries, as well as near-drowning, hypothermia and heat stroke – which is incidentally quite a bit more dangerous than I’d imagined), toxicology, a chapter on scoring systems used to assess severity of illness among patients in the ICU, and lastly a brief chapter about obstetric emergencies (pre-/eclampsia and HELLP-syndrome). So a lot of ground is covered here, meaning of course also that they do not go into as much detail in many of these chapters as they did in some of the first ones from which I quoted earlier.

I think reading a book like this may cause your viewing experience associated with watching medical dramas to change at least marginally. Some stuff from the remaining part of the book, as well as some comments:

“Traumatic brain injury
Primary brain injury occurs on impact and is considered irreversible. Secondary brain injury […] results from processes initiated by primary insult that occur some time later and may be prevented or ameliorated. Management of traumatic brain injury (TBI) aims to prevent secondary brain injury.”

“Management of organ donors
Once a potential organ donor has been identified, the regional transplant coordinator should be contacted, but he or she should not be involved in the process of diagnosing brain death or obtaining consent for organ donation. In general, the following features exclude eligibility for organ donation: malignancy (except for primary cerebral, skin, or lip), HIV, hepatitis, intravenous drug abuse, active tuberculosis, and sepsis. However, the regional transplant coordinator should make the determination of eligibility. Once brain death has been declared and the family has consented to organ donation, an aggressive approach to preservation of organ function is crucial.”

“Management of hyponatremia
Correction must not exceed 20 mol/L per 48 h and generally at a rate of no more than 0.5 mmol/L per h.” I was curious to know why, so I looked it up – it turns out that really bad things can happen if adjustment is too fast – this may lead to CPM (central pontine myelinolysis). It’s a recurring theme in the book that adjustment speeds matter, and that optimal treatment does not always imply fast adjustment; to give but one other example this is also the case when it comes to treatment of DKA (“The initial aim is to inhibit ketogenesis, which is achieved with modest doses of insulin. Rapid reductions in blood glucose should be avoided”).

“Within 24 h of admission the majority of critically ill patients will develop stress-related mucosal damage. Clinically relevant bleeding causes hematemesis and/or melena; hypotension, tachycardia, or anemia occurs in 1–4% of patients. Those who develop stress-related mucosal disease, endoscopic signs of bleeding, or clinically important bleeding have a higher risk of death. […] Maintenance of an elevated intragastic pH has the potential to prevent stress-related mucosal disease. Studies have demonstrated that a pH of more than 4.0 is adequate to prevent stress ulceration. However, a pH greater than 6.0 may be necessary to maintain clotting in patients at risk from rebleeding in peptic ulcer disease. […] There are, however, concerns that the elevation in pH in patients may lead to increased episodes of pneumonia.”

“Hypergastrinemia from a gastrinoma tumor causes Zollinger–Ellison syndrome (ZES) leading to gastric acid hypersecretion. Gastrin leads to hypertrophy and hyperplasia of the parietal cells which, in turn, also results in gastric acid hypersecretion. Although a rare disease, it is life threatening. […] ZES can be cured in 30% of patients by surgical resection. More than 50% of patients with control of acid hypersecretion who are not cured will die of tumor-related causes. Surgical resection should, therefore, be pursued whenever possible.” (‘More than 50% of patients with control of acid hypersecretion who are not cured will die of tumor-related causes’ – I’m starting to like my diabetes…)

In chapter 8 it’s noted that 50% of acute liver failure cases in the UK are caused by acetaminophen overdose, and that the various forms of viral hepatitis are behind another 40% of cases.

“Severe infection is not only a common cause of admission to intensive care, but also the most common complication suffered by critically ill patients. […] Hospital-acquired pneumonia (HAP) is defined as a pneumonia diagnosed 48 h or more after admission, which was not incubating at the time of admission. In contrast to the hospital population as a whole (in whom urinary tract and wound infections are more frequent), it is the most common infection in the critically ill, and is associated with a mortality rate of up to 50%.”

No, these are not all caused by the poor hand hygiene of nurses and doctors; 10 specific risk factors are listed and it’s made clear that:

“Although community-acquired pathogens can cause HAP, there is a much higher incidence of infection caused by aerobic Gram-negative bacilli. This is possibly the result of overgrowth of the stomach with intestinal bacteria, or the direct vascular spread of organisms that have translocated across the intestinal wall into the circulation.” On a related note, “There is no clear evidence that duration of residence in itself increases the risk of [nosocomial] bacteremia.” The chapter has some great (and/but brief) descriptions of various antibiotics, antivirals and antifungal medications. Some of the descriptions make it very obvious why such drugs are not always as great as they tend to be made out to be – here’s a presumably well-known example:

“Vancomycin inhibits cell wall synthesis. It is the drug of choice in the treatment of MRSA and coagulase-negative staphylococci that are resistant to meticillin.” Sounds great. But here’s the next sentence: “However, it is nephrotoxic and ototoxic, and serum levels must be monitored carefully.” (To those who don’t speak medical textbook, vancomycin may cause kidney failure and cause you to go deaf.)

“Respiratory function is often compromised in patients with cervical cord injury […] The level of injury critically influences the effect on ventilation […] Patients with lesions above C5 (unable to move hands or arms) usually require ventilation. Patients with intact C5 innervation (can shrug shoulders and externally rotate arms) may maintain adequate respiratory function in the absence of any other pulmonary insult. Patients with lesions at C6 will usually manage without ventilatory support in the acute phase.” Spinal cord damage can cause a lot of ugly stuff to happen besides ‘just’ being unable to move limbs – there may also be systemic problems such as various gastrointestinal problems, bladder distension and urinary retention, and loss of ability to regulate normal body temperature (Poikilothermia) as well as other metabolic problems.

“Supportive care is the basis of all treatment in poisoned patients. A medical history and physical examination can help direct which toxins or poisons are involved. It is important to seek out all sources of information because obtaining a history from an attempted suicide patient may be difficult. There may be deliberate misinformation in this setting. One must always assess for coingestions, as most patients who attempt suicide will use two or more toxins. […] Specific poison assays are often unhelpful as absorption is variable and a poor guide to prognosis. […] There are a limited number of poisons that have specific antidotes […] Many antidotes are toxic in their own right and should be reserved for life-threatening poisonings.”

August 26, 2013 - Posted by | books, health care, medicine

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