Steven E. Hill

Fatal Microvascular Pulmonary Emboli From Precipitation of a Total Nutrient Admixture Solution

BACKGROUND Paroxysmal respiratory failure and death occurred in two young adult females with pelvic infections. Autopsy revealed an amorphous material containing calcium obstructing the pulmonary microvasculature of each patient. Both patients received an identical total nutrient admixture (TNA) solution before their deaths. METHODS Infusion of TNA into an animal model was undertaken in an effort to reproduce the clinical effect. Laboratory investigation was also performed to isolate a precipitate and identify the factors contributing to precipitation. RESULTS A nonvisible precipitate containing calcium, phosphorus, and organic material was isolated from the TNA solution. Infusion of the formulation into healthy pigs resulted in sudden death within 4 hours. Alteration of the amino acid component, mix sequence, agitation technique, and mixing container influenced precipitate formation. CONCLUSION Pulmonary embolization of a precipitate containing calcium phosphate resulted in the death of two patients. The pH of the amino acid component, transient elevation of calcium and phosphorus concentrations during mixing, and the lack of agitation during automated preparation of the formulation were identified as the etiologic factors producing the fatal precipitate.

Effects of extreme hemodilution during cardiac surgery on cognitive function in the elderly

Background:Strategies for neuroprotection including hypothermia and hemodilution have been routinely practiced since the inception of cardiopulmonary bypass. Yet postoperative neurocognitive deficits that diminish the quality of life of cardiac surgery patients are frequent. Because there is uncertainty regarding the impact of hemodilution on perioperative organ function, the authors hypothesized that extreme hemodilution during cardiac surgery would increase the frequency and severity of postoperative neurocognitive deficits. Methods:Patients undergoing coronary artery bypass grafting surgery were randomly assigned to either moderate hemodilution (hematocrit on cardiopulmonary bypass ≥27%) or profound hemodilution (hematocrit on cardiopulmonary bypass of 15–18%). Cognitive function was measured preoperatively and 6 weeks postoperatively. The effect of hemodilution on postoperative cognition was tested using multivariable modeling accounting for age, years of education, and baseline levels of cognition. Results:After randomization of 108 patients, the trial was terminated by the Data Safety and Monitoring Board due to the significant occurrence of adverse events, which primarily involved pulmonary complications in the moderate hemodilution group. Multivariable analysis revealed an interaction between hemodilution and age wherein older patients in the profound hemodilution group experienced greater neurocognitive decline (P = 0.03). Conclusions:In this prospective, randomized study of hemodilution during cardiac surgery with cardiopulmonary bypass in adults, the authors report an early termination of the study because of an increase in adverse events. They also observed greater neurocognitive impairment among older patients receiving extreme hemodilution.

Efficacy of Single-dose, Multilevel Paravertebral Nerve Blockade for Analgesia after Thoracoscopic Procedures

Background:Although video-assisted thoracoscopic surgery for pulmonary resection is increasingly chosen over thoracotomy, the optimal analgesia regimen for thoracoscopy is unknown. The purpose of this trial was to compare the efficacy of analgesia from preoperative bupivacaine paravertebral nerve blockade with that from placebo injections. Methods:Eighty adult patients undergoing unilateral thoracoscopic procedures were enrolled in a prospective, double-blinded, randomized clinical trial of preoperative, multilevel, single-dose paravertebral nerve blockade. Patients received six paravertebral injections with 5 ml of either 0.5% bupivacaine with 0.0005% epinephrine (treated, n = 40) or preservative-free saline (control, n = 40). Cumulative weight-adjusted intraoperative fentanyl and postoperative patient-controlled morphine usage, visual analog pain scores, and spirometry were used to compare efficacy of analgesia between groups. Results:The treated group received significantly less intraoperative fentanyl compared with the control group (P = 0.003) and had a 31% smaller cumulative patient-controlled morphine dose (P = 0.03) in the 6 h after block placement. Within 6 h, treated patients also reported lower maximum pain scores (P = 0.02) and demonstrated less pain score variability (P = 0.01). No statistically significant difference in cumulative morphine usage existed at 12 or 18 h after block placement. No significant difference in spirometry, cortisol levels, or cytokine production was found between treatments. Conclusions:Single-dose paravertebral nerve blockade with bupivacaine is effective in reducing pain after thoracoscopic surgery, but only during the first 6 h after nerve blockade. Because of the limited duration of effect with currently available local anesthetic agents, the current data suggest that, at present, this technique is not indicated in the setting of thoracoscopic surgery.

Intraoperative physiologic variables and outcome in cardiac surgery: part II. Neurologic outcome

BACKGROUND The impact of alterable physiologic variables on neurologic outcome after coronary artery bypass grafting procedures is unknown. The purpose of this study was to determine whether minimum intraoperative hematocrit, maximum glucose concentration, or mean arterial pressure during cardiopulmonary bypass influences risk-adjusted neurologic outcome after coronary artery bypass grafting. METHODS Outcome data from 2,862 patients undergoing coronary artery bypass grafting were merged with intraoperative physiologic data. A preoperative stroke risk index was calculated for each patient. Variables found significant by univariate logistic regression were tested in a multivariable model to determine association with outcome. RESULTS The incidence of stroke or coma in the study population was 1.3%. After controlling for stroke risk and bypass time, only an index of low mean arterial pressure during bypass retained a significant inverse association with outcome (p = 0.0304). CONCLUSIONS This study found no evidence that glucose concentration or minimum hematocrit are associated with major adverse neurologic outcome. The association between lower pressure during bypass and decreased incidence of stroke or coma persisted in all risk groups. This points to mechanisms other than hypoperfusion as the primary cause of neurologic injury associated with cardiac surgery.

Intraoperative physiologic variables and outcome in cardiac surgery: Part I. In-hospital mortality.

BACKGROUND Risk stratification schemes have been developed to predict outcome of coronary artery bypass grafting (CABG) procedures, which are predominately based upon unalterable preoperative patient characteristics. The purpose of this study was to determine if minimum intraoperative hematocrit, maximum glucose concentration, mean arterial pressure on cardiopulmonary bypass, or duration of bypass influence risk-adjusted in-hospital mortality after CABG. METHODS Outcome data from 2,862 CABG patients were merged with intraoperative physiologic data. A preoperative mortality risk index was calculated for each patient. Variables found significant (p<0.05) by univariate logistic regression were tested in a multiple variable model to determine risk-adjusted association with mortality. RESULTS Overall mortality rate was 1.85%. The preoperative risk index was significantly associated with mortality (p = 0.0001). No significant association was present between mortality and intraoperative variables. Preexisting hypertension was an independent predictor of mortality after controlling for risk index and bypass duration. CONCLUSIONS Preexisting hypertension proved to be an independent predictor of mortality in our patient population. This study found no evidence to support the hypothesis that mean arterial pressure less than 50 mm Hg, lower hematocrit, or elevated glucose while on bypass increases in-hospital mortality.

Comparison of visually estimated blood loss with direct hemoglobin measurement in multilevel spine surgery.

Estimates of blood loss in the operating room are typically performed as a visual assessment by providers, despite multiple studies showing this to be inaccurate. Use of a less subjective measurement of blood loss such as direct measurement of the hemoglobin (Hb) mass lost from the surgical field may better quantify surgical bleeding. The objective of this investigation was to compare anesthesiologist estimates of intraoperative blood loss with measured Hb loss.

Jehovah's Witnesses and cardiac surgery: A single institution's experience

Based on biblical doctrines, patients of the Jehovahs Witness faith refuse allogeneic blood transfusion. Cardiac surgery carries a high risk of blood transfusion, but has been performed in Jehovahs Witnesses for many years. The literature contains information on the outcomes of this cohort, but does not detail the perioperative care of these patients. This article describes a single institutions experience in perioperative care of Jehovahs Witnesses undergoing cardiac surgery.

Use of hemoglobin raffimer for postoperative life-threatening anemia in a Jehovah's Witness.

PurposeTo describe the successful treatment of acute, life-threatening anemia with the oxygen therapeutic agent, hemoglobin (Hb) raffimer.Clinical featuresA 53-yr-old female Jehovah’s Witness developed severe anemia following total hip replacement. Due to prior patient directive, red blood cells were not transfused. Tachycardia, hypotension, electrocardiographic abnormalities and mental status changes developed with a nadir Hb concentration of 3.2 g.dL-1. Hb raffimer is a purified, cross-linked, human Hb solution developed as a substitute for red blood cell Hb. After obtaining informed consent as well as Food and Drug Administration and Institutional Review Board approval for compassionate use, 2 L of Hb raffimer (Hemolink, Hemosol, Inc., Toronto, ON, Canada) were administered along with ferrous sulfate and epoetin alfa therapy. The patient’s Hb level rose to 5.5 g.dL-1 with resolution of symptoms. To allow recovery of red blood cell mass while maintaining Hb level > 4.5 g.dL-1, additional 1000 mL doses of Hb raffimer were administered on postoperative days three, five and seven (total dose = 500 g Hb). The patient developed no serious adverse events related to treatment with Hb raffimer. By postoperative day 14, the patient’s Hb level increased to 6.5 g.dL-1 with a hematocrit of 23%. The patient was discharged.ConclusionsUse of Hb raffimer as a bridge to recovery of this patient’s red blood cell mass may have prevented adverse clinical outcome. Because this product is a purified Hb solution devoid of other cellular components, it may be accepted as therapy by patients who, due to religious conviction, refuse allogeneic red blood cell transfusion.ObjectifDécrire le traitement réussi d’une grave anémie aiguë avec un agent d’oxygénothérapie, un raffimère d’hémoglobine (Hb).éléments cliniquesUne femme de 53 ans, témoin de Jéhovah, souffrait d’anémie sévère post-arthroplastie totale de la hanche. Elle refusait toute transfusion sanguine. De la tachycardie, de l’hypotension, des anomalies électrocardiographiques et des changements de l’état mental sont apparus avec une concentration d’Hb minimale de 3,2 g.dL-1. Le raffimère d’Hb est une solution d’Hb humaine purifiée, polymérisée, développée comme substitut de l’Hb des globules rouges. Avec l’approbation, pour usage humanitaire, de la patiente, de la Food and Drug Administration et du Comité d’examen de l’institution, 2 L de raffimère d’Hb (Hemolink, Hemosol, Inc., Toronto, ON, Canada) ont été administrés avec du sulfate ferreux et de l’érythropoïétine humaine. L’Hb s’est élevée à 5,5 g.dL-1 avec la résolution des symptômes. Pour assurer la récupération de la masse sanguine tout en maintenant le niveau d’Hb > 4,5 g.dL-1, des doses additionnelles de 1000 mL de raffimère d’Hb ont été donnés aux jours trois, cinq et sept postopératoires (dose totale = 500 g d’Hb). Aucune complication sérieuse liée au raffimère d’Hb ne s’est développée. Au jour postopératoire 14, le niveau d’Hb est monté à 6,5 g.dL-1 avec un hématocrite de 23 %. La patiente a reçu son congé.ConclusionLe raffimère d’Hb, utilisé pour favoriser la récupération de la masse sanguine peut avoir évité des complications cliniques. Cette solution d’Hb purifiée dépourvue d’autres composantes cellulaires peut constituer un traitement acceptable aux patients qui, par conviction religieuse, refusent une transfusion allogénique.

Bipolar tissue sealant device decreases hemoglobin loss in multilevel spine surgery

BACKGROUND: Traditional techniques for obtaining hemostasis during orthopedic surgery, such as conventional electrocautery and sealants, have limited clinical effectiveness in reducing hemoglobin (Hb) loss and requirement for transfusion. The bipolar tissue sealant device studied in this trial combines radiofrequency energy with saline irrigation to hemostatically seal both cut bone and soft tissue, potentially aiding hemostasis.

Serum creatinine patterns in coronary bypass surgery patients with and without postoperative cognitive dysfunction

Renal dysfunction is common after coronary artery bypass graft (CABG) surgery. We have previously shown that CABG procedures complicated by stroke have a threefold greater peak serum creatinine level relative to uncomplicated surgery. However, postoperative creatinine patterns for procedures complicated by cognitive dysfunction are unknown. Therefore, we tested the hypothesis that postoperative cognitive dysfunction is associated with acute perioperative renal injury after CABG surgery. Data were prospectively gathered for 282 elective CABG surgery patients. Psychometric tests were performed at baseline and 6 wk after surgery. Cognitive dysfunction was defined both as a dichotomous variable (cognitive deficit [CD]) and as a continuous variable (cognitive index). Forty percent of patients had CD at 6 wk. However, the association between peak percentage change in postoperative creatinine and CD (parameter estimate = −0.41;P = 0.91) or cognitive index (parameter estimate = −1.29;P = 0.46) was not significant. These data indicate that postcardiac surgery cognitive dysfunction, unlike stroke, is not associated with major increases in postoperative renal dysfunction.