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.

Accuracy in Identifying the Cricothyroid Membrane, Dr. P. Lee

Paul Lee, DO

Article review

Accuracy of Identification of the Cricothyroid Membrane in Female Subjects Using Palpation: An Observational Study

The cricothyroid membrane (CTM) is the recommended site of access to the airway during cricothyroidotomy to provide emergency oxygenation. Despite the apparent simplicity of the technique, this rescue maneuver frequently fails to achieve its goals and complications are numerous. The reasons for this failure are unclear. We sought to determine the ability of physicians to correctly identify the CTM in female patients. Using fluorescent “invisible” ink, the physician was asked to mark the CTM with the patient in the supine neutral position and then with the head extended. The actual level was identified using ultrasound and the distance between the actual and estimated margin of the CTM was measured. A correct estimation was defined as a mark made between the upper and lower limits of the membrane and within 5 mm of midline. Participants were also asked to assess the ease of CTM palpation using a 10-cm visual analog scoring (VAS) scale. Fifty-six patients participated of whom 15 were obese. In the supine neutral neck position, the CTM was identified in 10/41 vs 0/15 (P = 0.048) in nonobese versus obese, respectively. Of the 46 incorrectly identified CTMs in this position, 24 were above (maximum 3 cm) and 22 below (maximum 3 cm) the actual level. Similar results were observed when the patients were placed with the neck in the extended position; the CTM was identified correctly in 12/41 vs 1/15 nonobese and obese patients, respectively. The range of values was also extensive; the estimation of the position of the membrane was as high as 2.5 cm above and 4 cm below the actual level, and up to 1.6 cm laterally. Participating doctors found palpation of the CTM subjectively more difficult in the obese than nonobese groups; VAS score for palpation difficulty was 5.25 ± 2.5 vs 3.3 ± 2.5, respectively, P = 0.005. Using multiple linear regression, VAS scores for palpation correlated negatively with increased patient height (P < 0.001) and greater thyromental distance (P = 0.006), and correlated positively with increased sternomental distance (P = 0.011) and neck circumference (P = 0.001). Misidentification of the CTM in female patients is common and its localization is less precise in those who are obese. This has implications for the likely success of invasive airway access via the CTM. Emergency cricothyroidotomy is a life-saving maneuver that may prevent death or permanent neurological injury in the event of difficult or failed airway management and is thus a core skill for anesthesiologists. Despite its crucial importance, it is a rare requirement in clinical practice. Consequently, individual clinical experience, even for experienced anesthesiologists, is infrequent and may in fact be a once-in-a-career event. Clearly, accurate anatomic localization of the cricothyroid membrane (CTM) is of critical importance before emergency cricothyroidotomy. Should the CTM be misidentified and the invasive airway device be misplaced, the consequences include continued hypoxia, airway trauma, esophageal penetration/perforation, and vascular and neural injury. The ability of clinicians to accurately identify the CTM has not been studied extensively. The purpose of this study was to determine the accuracy of clinical identification of the CTM using the traditional palpation technique. We hypothesized that the CTM would be more likely to be misidentified in obese patients than in normal weight patients on the basis that anatomical landmarks might be obscured