Edward A. Bittner

Postoperative residual curarization from intermediate-acting neuromuscular blocking agents delays recovery room discharge

BACKGROUND Postoperative residual curarization (PORC) [train-of-four ratio (T4/T1) <0.9] is associated with increased morbidity and may delay postoperative recovery room (PACU) discharge. We tested the hypothesis that postoperative T4/T1 <0.9 increases PACU length of stay. METHODS At admission to the PACU, neuromuscular transmission was assessed by acceleromyography (stimulation current: 30 mA) in 246 consecutive patients. The potential consequences of PORC-induced increases in PACU length of stay on PACU throughput were estimated by application of a validated queuing model taking into account the rate of PACU admissions and mean length of stay in the joint system of the PACU plus patients recovering in operation theatre waiting for PACU beds. RESULTS PACU length of stay was significantly longer in patients with T4/T1 <0.9 (323 min), compared with patients with adequate recovery of neuromuscular transmission (243 min). Age (P=0.021) and diagnosis of T4/T1 <0.9 (P=0.027), but not the type of neuromuscular blocking agent, were independently associated with PACU length of stay. The incidence of T4/T1 <0.9 was higher in patients receiving vecuronium. Delayed discharge significantly increases the chances of patients having to wait to enter the PACU. The presence of PORC is estimated to be associated with significant delays in recovery room admission. CONCLUSIONS PORC is associated with a delayed PACU discharge. The magnitude of the effect is clinically significant. In our system, PORC increases the chances of patients having to wait to enter the PACU.

Effects of Supervision by Attending Anesthesiologists on Complications of Emergency Tracheal Intubation

Background:Emergent intubation is associated with a high complication rate. These intubations are often performed by resident physicians in teaching hospitals. The authors evaluated whether supervision by an anesthesia-trained intensivist decreases complications of emergent intubations. Methods:The authors performed a prospective cohort study in an Academic Tertiary Care Hospital. They enrolled 322 consecutive patients who required emergent intubation between November 1, 2006, and April 15, 2008. Emergency intubations are performed by anesthesia residents during their surgical intensive care unit rotation. An attending anesthesiologist was assigned to supervise these intubations at predetermined periods. A respiratory therapist assisted with airway management and ventilation. Information related to the intubation, detailing patient demographics, indication for intubation, attending anesthesiologist presence, medications used, and immediate complications, was recorded. Disposition and duration of mechanical ventilation were also recorded. Results:There were no differences in demographics, clinical characteristics, or illness severity among patients intubated with and without attending supervision. Attending physician supervision was associated with a significant decrease in complications (6.1% vs. 21.7%; P = 0.0001). There was no difference in ventilator-free days or 30-day mortality. Conclusion:Supervision by an attending anesthesiologist was associated with a decreased incidence of complications during emergent intubations.

Early Mobilization in Critically Ill Patients: Patients' Mobilization Level Depends on Health Care Provider's Profession

To evaluate whether the level of mobilization achieved and the barriers for progressing to the next mobilization level differ between nurses and physical therapists.

A clinical assessment of the Mucus Shaver: A device to keep the endotracheal tube free from secretions

Objective:We evaluated a new device designed to clean the endotracheal tube in mechanically ventilated patients, the Mucus Shaver. Design:Prospective, randomized trial. Setting:University hospital intensive care unit. Patients:We enrolled 24 patients expected to remain ventilated for >72 hrs. Interventions:The Mucus Shaver is a concentric inflatable catheter for the removal of mucus and secretions from the interior surface of the endotracheal tube. The Mucus Shaver is advanced to the distal endotracheal tube tip, inflated, and subsequently withdrawn over a period of 3–5 secs. Patients were prospectively randomized within 2 hrs of intubation to receive standard endotracheal tube suctioning treatment or standard suctioning plus Mucus Shaver use until extubation. Measurements and Main Results:During the study period, demographic data, recent medical history, adverse events, and staff evaluation of the Mucus Shaver were recorded. At extubation, each endotracheal tube was removed, cultured, and analyzed by scanning electron microscopy. Twelve patients were assigned to the study group and 12 were assigned to the control group. No adverse events related to the use of the Mucus Shaver were observed. At extubation, only one endotracheal tube from the Mucus Shaver group was colonized, whereas in the control group ten endotracheal tubes were colonized (8% vs. 83%; p < .001). Scanning electron microscopy showed little secretions on the endotracheal tubes from the study group, whereas thick bacterial deposits were present on all the endotracheal tubes from the control group (p < .001 by Fisher exact test, using a maximum biofilm thickness of 30 &mgr;m as cut-off). The nursing staff was satisfied by the overall safety, feasibility, and efficacy of the Mucus Shaver. Conclusions:The Mucus Shaver is a safe, feasible, and efficient device for endotracheal tube cleaning in the clinical setting. The Mucus Shaver is helpful in preventing endotracheal tube colonization by potentially harmful microorganisms.

The surgical intensive care unit optimal mobility score predicts mortality and length of stay.

Objectives:To test if the surgical intensive care unit optimal mobility score predicts mortality and intensive care unit and hospital length of stay. Design:Prospective single-center cohort study. Setting:Surgical intensive care unit of the Massachusetts General Hospital. Patients:One hundred thirteen consecutive patients admitted to the surgical intensive care unit. Investigations:We tested the hypotheses that the surgical intensive care unit optimal mobility score independent of comorbidity index, Acute Physiology and Chronic Health Evaluation II, creatinine, hypotension, hypernatremia, acidosis, hypoxia, and hypercarbia predicts hospital mortality, surgical intensive care unit and total hospital length of stay. Measurements and Main Results:Two nurses independently predicted the patients’ mobilization capacity by using the surgical intensive care unit optimal mobility score the morning after admission, whereas a third nurse recorded the achieved mobilization levels of patients at the end of the day. A multidisciplinary expert team measured patients’ grip strength and assessed their predicted mobilization capacity independently. Multivariate analysis revealed that the surgical intensive care unit optimal mobility score was the only independent predictor of mortality. Surgical intensive care unit optimal mobility score, hypotension, and hypernatremia (>144 mmol/L) independently predicted intensive care unit length of stay, whereas the surgical intensive care unit optimal mobility score and hypernatremia predicted total hospital length of stay. The Acute Physiology and Chronic Health Evaluation II score was not identified in the multivariate analysis. The surgical intensive care unit optimal mobility score was also a reliable and valid instrument in predicting achieved mobilization levels of patients. Conclusions:In surgical critically ill patients presenting without preexisting impairment of functional mobility, the surgical intensive care unit optimal mobility score is a reliable and valid tool to predict mortality and intensive care unit and hospital length of stay. (Crit Care Med 2012; 40:–1128)

Neuromuscular blocking agent administration for emergent tracheal intubation is associated with decreased prevalence of procedure-related complications.

Background:Emergent intubation is associated with a high rate of complications. Neuromuscular blocking agents are routinely used in the operating room and emergency department to facilitate intubation. However, use of neuromuscular blocking agents during emergent airway management outside of the operating room and emergency department is controversial. We hypothesized that the use of neuromuscular blocking agents is associated with a decreased prevalence of hypoxemia and reduced rate of procedure-related complications. Methods:Five hundred sixty-six patients undergoing emergent intubations in two tertiary care centers, Massachusetts General Hospital, Boston, MA, and the University of California Los Angeles, Ronald Reagan Medical Center, Los Angeles, CA, were enrolled in a prospective, observational study. The 112 patients intubated during cardiopulmonary resuscitation were excluded, leaving 454 patients for analysis. All intubations were supervised by attendings trained in Critical Care Medicine. We measured intubating conditions, oxygen saturation during and 5 mins following intubation. We assessed the prevalence of procedure-related complications defined as esophageal intubation, traumatic intubation, aspiration, dental injury, and endobronchial intubation. Results:The use of neuromuscular blocking agents was associated with a lower prevalence of hypoxemia (10.1% vs. 17.4%, p = .022) and a lower prevalence of procedure-related complications (3.1% vs. 8.3%, p = .012). This association persisted in a multivariate analysis, which controlled for airway grade, sedation, and institution. Use of neuromuscular blocking agents was associated with significantly improved intubating conditions (laryngeal view, p = .014; number of intubation attempts, p = .049). After controlling for the number of intubation attempts and laryngoscopic view, muscle relaxant use is an independent predictor of complications associated with emergency intubation (p = .037), and there is a trend towards improvement of oxygenation (p = .07). Conclusion:The use of neuromuscular blocking agents, when used by intensivists with a high level of training and experience, is associated with a decrease in procedure-related complications.

Ketamine activates breathing and abolishes the coupling between loss of consciousness and upper airway dilator muscle dysfunction.

Background: Procedural sedation is frequently performed in spontaneously breathing patients, but hypnotics and opioids decrease respiratory drive and place the upper airway at risk for collapse. Methods: In a randomized, controlled, cross-over, pharmaco-physiologic study in 12 rats, we conducted acute experiments to compare breathing and genioglossus electromyogram activity at equianesthetic concentrations of ketamine, a noncompetitive N-methyl-D-aspartate receptor antagonist that combines potent analgesic with hypnotic action effects, versus propofol. In 10 chronically instrumented rats resting in a plethysmograph, we measured these variables as well as electroencephalography during five conditions: quiet wakefulness, nonrapid-eye-movement sleep, rapid eye movement sleep, and low-dose (60 mg/kg intraperitoneally) and high-dose ketamine anesthesia (125 mg/kg intraperitoneally). Results: Ketamine anesthesia was associated with markedly increased genioglossus activity (1.5 to fivefold higher values of genioglossus electromyogram) compared with sleep- and propofol-induced unconsciousness. Plethysmography revealed a respiratory stimulating effect: higher values of flow rate, respiratory rate, and duty-cycle (effective inspiratory time, 1.5-to-2-fold higher values). During wakefulness and normal sleep, the &dgr; (f = 6.51, P = 0.04) electroencephalogram power spectrum was an independent predictor of genioglossus activity, indicating an association between electroencephalographic determinants of consciousness and genioglossus activity. Following ketamine administration, electroencephalogram power spectrum and genioglossus electroencephalogram was dissociated (P = 0.9 for the relationship between &dgr;/&thgr; power spectrum and genioglossus electromyogram). Conclusions: Ketamine is a respiratory stimulant that abolishes the coupling between loss-of-consciousness and upper airway dilator muscle dysfunction in a wide dose-range. Ketamine compared with propofol might help stabilize airway patency during sedation and anesthesia.

Prospective Study of Vitamin D Status at Initiation of Care in Critically Ill Surgical Patients and Risk of 90-Day Mortality

Objectives:1) To characterize vitamin D status at initiation of critical care in surgical ICU patients and 2) to determine whether this vitamin D status is associated with the risk of prolonged hospital length of stay, 90-day readmission, and 90-day mortality. Design:Prospective cohort study. Setting:A teaching hospital in Boston, MA. Patients:Hundred surgical ICU patients. Interventions:None. Measurements and Main Results:Mean (± SD) serum total 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels were 17 ± 8 ng/mL and 32 ± 19 pg/mL, respectively. Mean calculated bioavailable 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were 2.5 ± 2.0 ng/mL and 6.6 ± 5.3 pg/mL, respectively. Receiver-operating characteristic curve analysis demonstrated that all of four vitamin D measures predicted the three clinical outcomes; total 25-hydroxyvitamin D was not inferior to the other measures. Median (interquartile range) hospital length of stay was 11 days (8–19 d). Poisson regression analysis, adjusted for biologically plausible covariates, demonstrated an association of total 25-hydroxyvitamin D with hospital length of stay (incident rate ratio per 1 ng/mL, 0.98; 95% CI, 0.97–0.98). The 90-day readmission and mortality rates were 24% and 22%, respectively. Even after adjustment for biologically plausible covariates, there remained significant associations of total 25-hydroxyvitamin D with readmission (odds ratio per 1 ng/mL, 0.84; 95% CI, 0.74–0.95) and mortality (odds ratio per 1 ng/mL, 0.84; 95% CI, 0.73–0.97). Conclusions:Serum 25-hydroxyvitamin D levels within 24 hours of ICU admission may identify patients at high risk for prolonged hospitalization, readmission, and mortality. Randomized trials are needed to assess whether vitamin D supplementation can improve these clinically relevant outcomes in surgical ICU patients.

Case Scenario: Acute Postoperative Negative Pressure Pulmonary Edema

A 25-yr-old man (weight, 68 kg; height, 183 cm) presentedto the surgery center for excision of back and thigh schwan-nomas on the same day. The patient’s medical history wassignificant only for his history of multiple schwannoma re-sections and a history of smoking one pack of cigarettes perweek for the past 5 yr. He denied previous problems withgeneral anesthesia, and his baseline peripheral oxygen satu-ration was 99% on ambient air.Thepatientwaspremedicatedwith2mgmidazolam,andanesthesia was induced with 250 mg fentanyl, 500 mg thio-pental, and 8 mg vecuronium given for facilitation of tra-cheal intubation. He was atraumatically intubated with a7-mm ID endotracheal tube using a no. 3 Macintosh laryn-goscope (Teleflex Medical, Research Triangle Park, NC) onthe first attempt with direct visualization of the vocal cords.The patient was turned prone, bilateral breath sounds werereconfirmed, and schwannoma excisions were performed ontheleftthighandtheleftflank.Atotalof0.5mghydromor-phone was administered for analgesia. The intraoperativecoursewasunremarkable.Thepatientwashemodynamicallystable with minimal blood loss and was easily ventilated andoxygenated. A total of 500 ml lactated Ringer’s solution wasadministeredduringthe65-minsurgicalprocedure.Thepa-

Temporal trends in the epidemiology of severe postoperative sepsis after elective surgery: a large, nationwide sample.

Introduction:Multiple studies have used administrative datasets to examine the epidemiology of sepsis in general, but the entity of postoperative sepsis has been studied less intensively. Therefore, we undertook an analysis of the epidemiology of postoperative sepsis using the Nationwide Inpatient Sample, the largest in-patient dataset available in the United States. Methods:Elective admissions of patients aged 18 yr or older with a length of stay more than 3 days for any 1 of the 20 most common elective operative procedures were extracted from the dataset for the years 1997–2006. Postoperative sepsis was defined using the appropriate International Classification of Diseases, Ninth Revision, Clinical Modification codes; severe sepsis was defined as sepsis along with organ dysfunction. Logistic regression was used to assess the significance of temporal trends after adjusting for relevant demographic characteristics, operative procedure, and comorbid conditions. Results:We identified 2,039,776 admissions for analysis. The rate of severe sepsis increased from 0.3% in 1997 to 0.9% in 2006. This trend persisted after adjusting for relevant covariables—the adjusted odds ratio of severe sepsis per year increase in the study period was 1.12 (95% CI, 1.11–1.13; P < 0.001). The in-hospital mortality rate for patients with severe postoperative sepsis declined from 44.4% in 1997 to 34.0% in 2006; this trend also persisted after adjustment for relevant covariables—the adjusted odds ratio per year was 0.94 (95% CI, 0.93–0.95; P < 0.001). Conclusion:During the 10-yr period that we studied, there was a marked increase in the rate of severe postoperative sepsis but a concomitant decrease in the in-hospital mortality rate in severe sepsis.