Tuesday, 22 July 2008

Prostration Equals Intubation

Dear Bloggers

Today I want to touch on the topic of aspiration. This is a common medical problem in Japan and the aspiration of food or gastric contents can be due to a whole host of medical and surgical problems which predispose for these substances to enter the respiratory tract to cause both chemical induced inflammation and polymicrobial infection.

All the famous textbooks can tell you the history, physical, examination x-ray findings, bacterial culture results and treatment modalities.

I want to concentrate on a simple thing-- patient positioning.

Take for example, a patient with a small bowel obstruction 小腸の閉塞. Such patients have frequent vomiting and are at significant risk of aspiration of bowel contents which include gastric acid and organisms. Such patients normally require nasogastric tube suction to prevent the contents from regurgitating leading to aspiration. Moreover, intravenous fluid administration and a strict nil by mouth regimen should be adhered to until the problem is resolved.

Patient positioning is extremely important. If a patient is lying flat at 180 degrees (prostrate) and if there is incomplete closure of the functional valve at the lower oesophageal sphincter, there is a real risk of regurgitation / vomiting with secondary aspiration. Having visited many hospitals in Japan, it is very variable whether patients are nursed flat or at an incline.

If patients are nursed at an incline, gravity helps the patient to reduce the likelihood of the regurgitation effect. It is not at all fool proof as patients nursed at an incline can still vomit and aspirate, but the 'head up' incline certainly reduces the risk of aspiration although, I would also advocate additional NG tube suction, intravenous fluid and nil per oral regimen otherwise known in the UK as 'drip and suck'.

If the patient has contraindications to being nursed at an incline e.g. shock, trauma, then the patient should ideally be nursed in the 'recovery position' or if not possible, to protect the airway with an endotracheal tube still with concomittant NG drainage of the gastric contents. The tracheal intubation is a drastic move but may be necessary if the other approaches are not feasible.

However, if the patient has no obvious contraindications, please consider raising the head of the bed e.g. 30 degrees or higher if need be, to ensure that the head of the patient is at an safe incline rather than flat, in order to reduce the risk of aspiration.

Although patients in Japan are commonly nursed in the flat / prostrate position, there is no evidence that there is any need for them to be nursed in such a position.

Moreover, as I have eluded to in previous blogs, patients with chronic lung disease, heart failure, acute myocardial infarction, etc should all be nursed at an incline e.g. 45, 90 degrees depending on the severity of their disease in order to aid respiration. Lying such patients flat is not helpful for their conditions and aspiration can occur here to worsen the scenario.

UpToDate 16.1 also advocates nursing patients at an incline. Please check out their website.

Professor Alan Lefor, Resident Professor of Surgery, Jichi Medical University (previously Prof of Surgery and Oncology at Cedars-Sinai Medical Center, USA) has kindly commented on the aspect of aspiration per se and ventilated patients.

In the USA, all patients on ventilators are expected to have the “ventilator bundle” which is defined as

The key components of the Ventilator Bundle are:

· Elevation of the Head of the Bed

· Daily "Sedation Vacations" and Assessment of Readiness to Extubate

· Peptic Ulcer Disease Prophylaxis

· Deep Venous Thrombosis Prophylaxis

This is an important quality measure in the USA, and by doing all 4 things, complication rates are significantly lower. Please note the inclusion of elevation of the head of the bed, as you emphasize.

By using anti-acid meds, if there is aspiration, it is not as serious.

I agree that positioning is critical, and that patients should have the head of the bed elevated.

Furthermore, it is critical to understand that nasogastric suction does NOT prevent aspiration, in fact by stenting open the LES [Lower Esophageal Sphincter], it may increase the rate of aspiration. Therefore, meticulous care is needed to assure that the tube is functioning well and emptying the stomach.

Also, aspiration is possible with endotracheal intubation. Thus, good clinical care and elevation of the head of the bed is required as well. Too many people think that once there is an NG or intubation that they don’t have to worry about aspiration. This is simply wrong.

Thank you as always Professor Lefor for such helpful comments.

As has been raised above, patients should be receiving thromboprophylaxis. This is indeed the case in the UK for any patient who is immobile and peri- /post- surgery. In fact, patients who are immobile >3 days or post-surgery are at increased risk of DVT-PE and to signify just how important it is, this is incorporated into the Modified Well's Score for PE prediction. Such patients, unless contraindicated, should receive Clexane (enoxaparin LMW heparin).

This may, however, not be possible in Japan as such therapy is not covered by the health insurance system. However, it is possible to provide subcutaneous unfractionated heparin twice daily e.g. 5000 U bd. Nevertheless, there is always the concern by physicians that patients may bleed on heparin. One has to measure the risk to benefit ratio of giving prophylactic heparin. The risk of bleeding with patients using LMWH is about 3-4% and such bleeds are usually non-life threatening. However, mortality from PE i.e. undiagnosed or untreated ranges from 30-40% (treated PE mortality is about 5%) . Hence, the numbers of risk to benefit are in favour of prophylaxis. Immobile patients are at risk of DVT and PE and there have been several cases of patients at various hospitals in Japan developing DVT-PE who were not receiving prior prophylaxis.

Moreover, in the UK, ICU patients are generally nursed with the head up with NG tube on free drainage / suction and IV proton pump inhibitors are given. Intravenous H2 blockers e.g. ranitidine, soon develop a reduced efficacy and are inferior compared to PPI therapy e.g. omeprazole / pantoprazole, the latter drugs which have the most evidence base. Again, as mentioned to by Prof Lefor, lying intubated patients flat is not helpful as it does not prevent aspiration and may also impair respiration.

Prof Lefor raised an extrememly important point with regards to attempting to extubate the patient. The longer the patient is maintained on pressure ventilation, which reduces the work of breathing in most instances, there is soon respiratory muscle wasting making it more difficult to eventually wean the patient off the ventilator. Of course, patients should be weaned as soon as is clinically safe to do so, but prolonged periods of intubation should be avoided at all costs to prevent the horror scenario of ventilator dependence.

I hope the above clinical discussion is helpful to all physicians...please consider....

Have a great day.....

No comments: