Patient Safety in Anesthesia - Recent Advances
Anesthesia administration and maintenance has made great strides since its infancy centuries ago. Among these improvements is a most crucial component - patient safety. Patient safety is paramount in all aspects of medicine and medical care, but there is a particular concern for safety and injury prevention in the perioperative setting where the patient is often exposed to significant risk. Fortunately, the last decade has seen significant improvements in several aspects of patient care in the realm of anesthesia.
Medicine should be evidence-based, and the discipline of Anesthesia is no exception. While experience and intuition certainly play a role in any practitioner’s decisions, empirical evidence alone cannot be relied upon when making potentially life-threatening or life-saving decisions.
This assertion is at the heart of the argument against “traditional” fluid management, or calculations using the “4/2/1 rule.”1 Firstly, it is argued that this method relies all too much on estimations and assumptions. For example, preoperative fluid loss is calculated by the anesthesia provider based on an estimation of the time since last oral intake.
Furthermore, estimations of fluid loss during the procedure are made according to the severity of tissue trauma associated with the procedure. Actual fluid loss varies widely from procedure to procedure based upon several factors like patient body habitus, surgical history, and surgical technique. While the traditional method may allow for adjustments with the standard guide of “3 mL of crystalloid for every 1 mL of blood loss,” this is an estimation albeit an educated one.1 Each estimation made introduces additional room for error.
Evidence pointing out the dangers of this approach can be found in the FEAST trial by Maitland et al. A total of 3141 febrile African children with perfusion impairment were studied in the trial. A 48-hour mortality rate of 10.6% was seen in the patients who received a 20-40 mL/kg bolus of normal saline upon admission, versus a 7.3% 48-hour mortality rate in the control group of patients who received no bolus.2
While the hazards of overly-restrictive fluid management are well-known and understood, giving too much fluid can be equally hazardous. Fluid management should be precise and must be backed by clinical evidence. As a paper in Clinics in Colon and Rectal Surgery stated, “Traditional methods of perioperative fluid management have emphasized a liberal approach to administration of fluids. Those traditional methods have now been called into question.“ This paper looked at a total of seven randomized trials that examined the effects of perioperative fluid restriction on patient outcomes. Although there were conflicting results, the majority of the trials found that restrictive fluid strategies were associated with better results.3
So what does this all mean for today’s anesthetist and CRNA? Modern fluid management equipment can actually make the job easier and less stressful as the contemporary methods of fluid maintenance do not rely on estimation.
In fact, one accurate tool for fluid management decisions endorsed by the National Health Service of the UK, esophageal Doppler monitoring (EDM), has shown promising results. Kuper et al. compared 658 major surgical procedures without EDM to 649 major procedures using EDM at three large English hospitals. They found “a 3.7 day reduction in total length of stay. Length of stay was reduced at each site, and in most specialities.”4
In summary, providing fluids in the anesthetic setting based on estimations or even general rules is proving to be less reliable. Rather, fluids should be given based on physiologic need and in pursuit of a specific improvement in patient condition, using up-to-date equipment. This does not mean that patients undergoing major procedures or in critical condition should not be monitored closely, it basically takes the practice of assumptions out of fluid management and relieves some stress from anesthesia personnel.
It is the responsibility of all operating room personnel, from surgeons to anesthetists, from CRNAs to surgical technologists, to make every effort to prevent infection opportunities. Unfortunately, it would appear that a potential source of contamination is often neglected - the ventilator.
According to a 2012 paper by Zingg et al., in one randomized trial the ventilator was the second most common infection origin. The most likely explanation was that the ventilator was contaminated by the gloved hands of anesthesia personnel and the contamination was then transferred to the next patient.5
The authors acknowledge that anesthesia providers already frequently wash their hands and almost constantly wear gloves in patient interactions.5 However, an additional infection-prevention measure can be adopted by the use of modern stopcocks, like the Marvelous™ . The Luer-activated valve in this stopcock acts as a barrier to bacteria, eliminating the need to open the line to access it. The constant flushing of the side port with (main line) carrier fluid that minimizes dead space and prevents stagnation, can further reduce the risk of bacterial colonization. The Marvelous further improves patient safety by the constant flushing of the internal valve volume. This feature assures complete rinsing of drugs from the system thereby reducing the chance of drug interactions and unintentional administration of residual drugs.
1. Stoelting, R.K. et al. Basics of Anesthesia, 5th ed. Elsevier, 2007; p. 349.
2. Maitland, K. et al. “Mortality after Fluid Bolus in African Children with Severe Infection.” NEJM. June 2011, 364(26);p.2483-2495. http://www.nejm.org/doi/pdf/10.1056/NEJMoa1101549
3. Bamboat, Z.M. et al. “Perioperative Fluid Management.” Clin Colon Rectal Surg. Feb 2009, 22(1);p.28-33. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2780230/
4. Kuper, M. et al. “Intraoperative fluid management guided by oesophageal Doppler monitoring.” BMJ. May 2011, 342;d3016. http://www.bmj.com/content/342/bmj.d3016.short
5. Zingg, W. et al. “Stopcock Contamination: The Source Does Not Explain It All.” Anesthesia & Analgesia. June 2012, 114(6);p.1151-1152. http://journals.lww.com/anesthesia-analgesia/Fulltext/2012/06000/Stopcock_Contamination___The_Source_Does_Not.3.aspx
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