Edward C. Nemergut

The Anesthesiologist's Role in the Prevention of Surgical Site Infections

SURGICAL site infections (SSIs) continue to be a substantial source of morbidity and mortality in the surgical patient population. They are the second most common cause of nosocomial infection after urinary tract infections and account for approximately 17% of all hospital-acquired infections. These infections lead to longer hospital and intensive care unit stays, lead to substantially increased mortality, and contribute significantly to healthcare costs. In a 1999 series of cardiac surgery patients, each deep sternal wound infection added an average of

Perioperative management of patients undergoing transsphenoidal pituitary surgery.

26,400 in hospital charges and increased the average duration of stay by 16 days. The incidence of SSI varies for each operative procedure, each surgeon, and each hospital. In addition, each patient presents with his or her own unique risk profile for the development of a SSI. Although sterile surgical technique is extremely important to the prevention of SSIs, there is increasing evidence that anesthesiologists play a prominent yet under appreciated role in the prevention of SSIs. While infections typically present several days postoperatively, the first few hours after bacterial contamination are the critical window for the establishment of infection. Therefore, decreasing SSIs hinges on the optimization of perioperative conditions, many of which are controlled by anesthesiologists. In this review, we will discuss the literature surrounding six perioperative factors over which anesthesiologists have at least partial control and how these factors may influence the risk of postoperative surgical site infection. Although we acknowledge that many anesthesiologists care for patients in the intensive care unit, we limit our discussion here to the immediate perioperative period.

Intraoperative Methadone Improves Postoperative Pain Control in Patients Undergoing Complex Spine Surgery

Pituitary adenomas often present with the symptoms of hormonal hypersecretion, and although medical therapy is available for most hyperfunctioning states, it is not curative. As a result, transsphenoidal pituitary surgery has become a commonly performed neurosurgical procedure with unique challenges for the anesthesiologist due to the distinct medical comorbidities associated with various adenomas. Any type of pituitary tumor may also produce hypopituitarism and local mass effects secondary to the expanding intrasellar mass. Here we review the perioperative concerns surrounding surgery to remove adenomas and decompress the sellar space. Special attention is given to Cushing’s disease (hypercortisolism secondary to an adrenocorticotropic hormone-secreting adenoma), acromegaly (secondary to a growth hormone-secreting adenoma), and hyperthyroidism in the setting of thyrotropic adenomas. Operative risks, including bleeding, diabetes insipidus, the syndrome of inappropriate antidiuretic hormone secretion, and hypopituitarism, are addressed in detail. Understanding preoperative assessment, intraoperative management, potential complications, their management, and strategies for avoidance are fundamental to successful perioperative patient care and avoidance of morbidity and mortality.

Preoperative Statin Administration Is Associated With Lower Mortality and Decreased Need for Postoperative Hemodialysis in Patients Undergoing Coronary Artery Bypass Graft Surgery

BACKGROUND:Patients undergoing complex spine surgery frequently experience severe pain in the postoperative period. The combined opiate receptor agonist/N-methyl-D-aspartate receptor antagonist methadone may be an optimal drug for these patients given the probable involvement of N-methyl-D-aspartate systems in the mechanism of opioid tolerance and hyperalgesia. METHODS:Twenty-nine patients undergoing multilevel thoracolumbar spine surgery with instrumentation and fusion were enrolled in this prospective study and randomized to receive either methadone (0.2 mg/kg) before surgical incision or a continuous sufentanil infusion of 0.25 &mgr;g/kg/h after a load of 0.75 &mgr;g/kg. Postoperative analgesia was provided using IV opioids by patient-controlled analgesia. Patients were assessed with respect to pain scores (visual analog scale from 0 to 10), cumulative opioid requirement, and side effects at 24, 48, and 72 hours after surgery. RESULTS:Demographic data, duration, and type of surgery were comparable between the groups. Methadone reduced postoperative opioid requirement by approximately 50% at 48 hours (sufentanil versus methadone group, median [25%/75% interquartile range]: 63 mg [27.3/86.1] vs 25 mg [16.5/31.5] morphine equivalents, P = 0.023; and 72 hours: 34 mg [19.9/91.5] vs 15 mg [8.8/27.8] morphine equivalents, P = 0.024) after surgery. In addition, pain scores were lower by approximately 50% in the methadone group at 48 hours after surgery (sufentanil versus methadone group [mean ± SD] 4.8 ± 2.4 vs 2.8 ± 2.0, P = 0.026). The incidence of side effects was comparable in both groups. CONCLUSION:Perioperative treatment with a single bolus of methadone improves postoperative pain control for patients undergoing complex spine surgery.

The Physiologic Implications of Isolated Alpha1 Adrenergic Stimulation

OBJECTIVE The purpose of this study was to examine the effect of perioperative statin administration on renal outcomes after cardiac surgery. DESIGN A retrospective chart review. SETTING A university hospital. PARTICIPANTS Patients presenting for cardiac surgery. INTERVENTIONS The records of 2,760 patients admitted for coronary artery bypass graft (CABG) surgery from 1997 to 2006 were reviewed. In-hospital mortality, the need for renal replacement therapy (RRT), and acute renal failure (ARF) were considered the primary outcomes. Univariate and multiple logistic regression analyses were performed to assess the relationship between each outcome and statin therapy while adjusting for other patient characteristics. MAIN RESULTS Of the 2,760 patients, 1,557 were taking preoperative statins. On univariate analysis, the mortality rate for patients receiving statins was 2.4% versus 4.2% for those not receiving statins (p = 0.008). The requirement for RRT was 1.9% for patients receiving statins versus 3.6% for those not receiving statins (p = 0.011). The incidence of ARF was not statistically significant between groups (28% v 27.5%). On multivariate analysis, statin therapy was associated with a 43% decrease in the risk of death and a 46% decrease in the risk of RRT, but statins were not associated with a decreased risk of ARF. Also, the beneficial effects of statins were age-dependent, with younger patients experiencing a greater advantage. CONCLUSIONS The preoperative use of statins is associated with decreased in-hospital mortality and a reduction in the need for RRT.

The Clinical Implications of Isolated Alpha1 Adrenergic Stimulation

Phenylephrine and methoxamine are direct-acting, predominantly &agr;1 adrenergic receptor (AR) agonists. To better understand their physiologic effects, we screened 463 articles on the basis of PubMed searches of “methoxamine” and “phenylephrine” (limited to human, randomized studies published in English), as well as citations found therein. Relevant articles, as well as those discovered in the peer-review process, were incorporated into this review. Both methoxamine and phenylephrine increase cardiac afterload via several mechanisms, including increased vascular resistance, decreased vascular compliance, and disadvantageous alterations in the pressure waveforms produced by the pulsatile heart. Although pure &agr;1 agonists increase arterial blood pressure, neither animal nor human studies have ever shown pure &agr;1-agonism to produce a favorable change in myocardial energetics because of the resultant increase in myocardial workload. Furthermore, the cost of increased blood pressure after pure &agr;1-agonism is almost invariably decreased cardiac output, likely due to increases in venous resistance. The venous system contains &agr;1 ARs, and though stimulation of &agr;1 ARs decreases capacitance and may transiently increase venous return, this gain may be offset by changes in afterload, venous compliance, and venous resistance. Data on the effects of &agr;1 stimulation in the central nervous system show conflicting changes, while experimental animal data suggest that renal blood flow is reduced by &agr;1-agonists, and both animal and human data suggest that gastrointestinal perfusion may be reduced by &agr;1 tone.

Postoperative Care Following Pituitary Surgery

Phenylephrine is a direct-acting, predominantly &agr;1 adrenergic receptor agonist used by anesthesiologists and intensivists to treat hypotension. A variety of physiologic studies suggest that &agr;-agonists increase cardiac afterload, reduce venous compliance, and reduce renal bloodflow. The effects on gastrointestinal and cerebral perfusion are controversial. To better understand the effects of phenylephrine in a variety of clinical settings, we screened 463 articles on the basis of PubMed searches of “methoxamine,” a long-acting &agr; agonist, and “phenylephrine” (limited to human, randomized studies published in English), as well as citations found therein. Relevant articles, as well as those discovered in the peer-review process, were incorporated into this review. Phenylephrine has been studied as an antihypotensive drug in patients with severe aortic stenosis, as a treatment for decompensated tetralogy of Fallot and hypoxemia during 1-lung ventilation, as well as for the treatment of septic shock, traumatic brain injury, vasospasm status–postsubarachnoid hemorrhage, and hypotension during cesarean delivery. In specific instances (critical aortic stenosis, tetralogy of Fallot, hypotension during cesarean delivery) in which the regional effects of phenylephrine (e.g., decreased heart rate, favorable alterations in Qp:Qs ratio, improved fetal oxygen supply:demand ratio) outweigh its global effects (e.g., decreased cardiac output), phenylephrine may be a rational pharmacologic choice. In pathophysiologic states in which no regional advantages are gained by using an &agr;1 agonist, alternative vasopressors should be sought.

Strict glucose control does not affect mortality after aneurysmal subarachnoid hemorrhage.

Patients undergoing surgery for pituitary tumors represent a heterogeneous population each with unique clinical, biochemical, radiologic, pathologic, neurologic, and/or ophthalmologic considerations. The postoperative management of patients following pituitary surgery often occurs in the context of a dynamic state of the hypothalamic-pituitary-end organ axis. Consequently, a significant component of the postoperative care of these patients focuses on vigilant screening and observation for neuroendocrinologic perturbations such as varying degrees of hypopituitarism and disorders of water balance (diabetes insipidus and the syndrome of inappropriate antidiuretic hormone). Additionally, one must be cognizant of other potential complications specific to the transsphenoidal approach for tumor removal including cerebrospinal fluid leakage and meningitis. This review addresses the postoperative management of patients undergoing pituitary surgery with an emphasis on careful screening and recognition of complications.

Error in central venous pressure measurement.

Background:The effects of both hyperglycemia and hypoglycemia are deleterious to patients with neurologic injury. Methods:On January 1, 2002, the neurointensive care unit at the University of Virginia Health System initiated a strict glucose control protocol (goal glucose < 120 mg/dl). The authors conducted an impact study to determine the effects of this protocol on patients presenting with aneurysmal subarachnoid hemorrhage. Results:Among the 834 patients admitted between 1995 and 2007, the in-hospital mortality was 11.6%. The median admission glucose for survivors was lower (135 vs. 176 mg/dl); however, on multivariate analysis, increasing admission glucose was not associated with a statistically significant increase in the risk of death (P = 0.064). The median average glucose for survivors was also lower (116 vs. 135 mg/dl). This was significant on multivariate analysis (P < 0.001); however, the effect was small (odds ratio, 1.045). Implementation of the strict glucose protocol decreased median average glucose (121 vs. 116 mg/dl, P < 0.001) and decreased the incidence of hyperglycemia. Implementation of the protocol had no effect on in-hospital mortality (11.7% vs. 12.0%, P = 0.876 [univariate], P = 0.132 [multivariate]). Protocol implementation was associated with an increased incidence of hypoglycemia (P < 0.001). Hypoglycemia was associated with a substantially increased risk of death on multivariate analysis (P = 0.009; odds ratio = 3.818). Conclusions:The initiation of a tight glucose control regimen lowered average glucose levels but had no effect on overall in-hospital mortality.

The Physiology of Cardiopulmonary Resuscitation.

BACKGROUND: The variability introduced by inconsistent placement of pressure transducers for invasive monitoring may result in significant measurement error. Our goals in this study were to quantify the degree of variation among health care providers and to identify a simple tool for reducing this error. METHODS: A sample of 50 perioperative health care providers was recruited and asked to place a transducer at the appropriate level for central venous pressure (CVP) monitoring on two separate occasions: first without any additional standardization tools and second with a laser level to guide transducer placement. The variability among providers was calculated, and the results between sessions compared. RESULTS: There was significant variation in transducer placement during both sessions, in some instances, of greater magnitude than a normal CVP value. The laser level did not significantly reduce this variation. CONCLUSION: There is significant variation in transducer placement among health care providers. This variation is not reduced by a laser level and must be considered when interpreting CVP data. Hospital- or institution-wide standardization of a zero-level should be considered.