Changing Paradigms in Surgical Rescuscitation, Dr. Perz

Katie Perz, D.O.

Patients undergoing emergency surgery typically require resuscitation, generally either because they are either hemorrhaging or septic. Intravascular hypovolemia is common at the time of anesthesia and needs to be treated appropriately based on its root cause; fluid resuscitation is different in bleeding and septic patients.  In bleeding patients, it is advisable to maintain a deliberately low blood pressure to facilitate clot formation and stabilization, which is described as controlled hypotension.  If massive transfusion is anticipated, blood products should be administered from the outset to prevent the coagulopathy of trauma.  Early use of plasma in a 1:1 ratio with pRBCs and FFP has been associated with improved outcomes.  In septic patients, early fluid loading is recommended.  The concept of “goal directed resuscitation is based on continuing resuscitation until venous oxygen saturation is normalized.  In either bleeding or septic patients, however, the most important goal remains surgical control of the source of pathology and nothing should delay transfer to the operating room. 

Newer modalities of fluid monitoring are in use, and while they are better than old modalities, they still lack validation.   The previous goal standard was CVP and PA catheters, but these methods of monitoring are falling out of favor and it is questionable whether they affect outcomes at all, or if they could possibly be leading to worse outcomes.  Echo (transthoracic or transesophageal) is a very accurate modality for assessing volume status, ventricular systolic function, cardiac output, etc. which makes it an excellent diagnostic tool, but it is an expensive technology and is highly dependent on operator experience, so it is not routinely appropriate for monitoring.  A new “goal-directed” approach to volume resuscitation is now present through new technologies that use a dynamic approach.  Arterial pressure wave form systems including the PiCCO, PulseCO, and FloTrac/Vigileo are less invasive and can possibly better assess volume status using the calculated values of stroke volume variation, pulse pressure variation, stroke volume, stroke volume index, cardiac output, and cardiac index.  SVV and PPV are more reliable indicators of volume responsiveness than SVP, PAOP, left ventricular rend diastolic volume index, and global end-diastolic volume index. 

The type of fluid is also important in volume resuscitation, and typical choices include crystalloids, colloids, hypertonic saline, or blood products.  Crystalloids are typically the beginning choice as they are inexpensive, plentiful and easy to administer.  However, they do not linger long in the bloodstream, can predispose a patient to hyperchloremic metabolic acidosis (NS), they do not carry oxygen, and can impede clotting, and are therefore be of limited value in resuscitation of hemorrhaging patients.  Colloids (hextend and albumin) are of value in that they can play a role in controlling cerebral blood flow, can preserve the microcirculation with a minimum volume, they may have anti-inflammatory properties, and remain in the intravascular space longer than crystalloids.  However, they may negatively affect coagulation or cause pulmonary edema at large doses, and have a higher risk of anaphylaxis.  Hypertonic saline is a newer and evolving modality involving small volume resuscitation.  Hypertonic saline acts like a magnet, drawing fluid from tissues into the bloodstream, thereby increasing circulating volume; additionally, it keeps this fluid in the intravascular space much longer than crystalloid.  It may improve microvascular flow, control ICP, and stabilize arterial pressure and cardiac output.  However, meta-analysis of clinical studies shows no significant improvement in survival with the use of hypertonic solutions for resuscitation in hemorrhagic shock at this time.  Finally, the pros and cons of utilizing blood products are well established.  Administration of blood products (including pRBCs, whole blood, FFP, and platelets) in the face of hemorrhage restores oxygen carrying capacity and supports coagulation; however, the “evils” of transfusion are well described, transfusion related acute lung injury is a common complication of FFP administration, and there is little doubt that increased exposure to blood products increases the long term risk of inflammatory complications.

In summary, resuscitation depends on correctly identifying the underlying pathophysiology, expediting surgical control, and supporting organ system perfusion.  Fluid administration is the mainstay of resuscitation but must be approached in a systematic fashion.  No perfect monitor exists to indicate the patient’s degree of shock, but newer modalities are promising.  In actively hemorrhaging patients, there is evidence to sugges3t that attempting to normalize blood pressure will increase mortality, and the timing and rate of fluid administration play a critical role in hemostasis.  Early use of blood products, especially plasma, may help to prevent the onset of coagulopathy.  The tactic of choice for managing patients with sepsis involves early fluid administration, judicious monitoring, and surgical control of the pathology, if necessary.