Michael O'Reilly

Incidence and predictors of difficult and impossible mask ventilation.

Background:Mask ventilation is an essential element of airway management that has rarely been studied as the primary outcome. The authors sought to determine the incidence and predictors of difficult and impossible mask ventilation. Methods:A four-point scale to grade difficulty in performing mask ventilation (MV) is used at the authors’ institution. They used a prospective, observational study to identify cases of grade 3 MV (inadequate, unstable, or requiring two providers), grade 4 MV (impossible to ventilate), and difficult intubation. Univariate and multivariate analyses of a variety of patient history and physical examination characteristics were used to establish risk factors for grade 3 and 4 MV. Results:During a 24-month period, 22,660 attempts at MV were recorded. 313 cases (1.4%) of grade 3 MV, 37 cases (0.16%) of grade 4 MV, and 84 cases (0.37%) of grade 3 or 4 MV and difficult intubation were observed. Body mass index of 30 kg/m2 or greater, a beard, Mallampati classification III or IV, age of 57 yr or older, severely limited jaw protrusion, and snoring were identified as independent predictors for grade 3 MV. Snoring and thyromental distance of less than 6 cm were independent predictors for grade 4 MV. Limited or severely limited mandibular protrusion, abnormal neck anatomy, sleep apnea, snoring, and body mass index of 30 kg/m2 or greater were independent predictors of grade 3 or 4 MV and difficult intubation. Conclusions:The authors observed the incidence of grade 3 MV to be 1.4%, similar to studies with the same definition of difficult MV. Presence of a beard is the only easily modifiable independent risk factor for difficult MV. The mandibular protrusion test may be an essential element of the airway examination.

Predictors of postoperative acute renal failure after noncardiac surgery in patients with previously normal renal function.

Background:The authors investigated the incidence and risk factors for postoperative acute renal failure after major noncardiac surgery among patients with previously normal renal function. Methods:Adult patients undergoing major noncardiac surgery with a preoperative calculated creatinine clearance of 80 ml/min or greater were included in a prospective, observational study at a single tertiary care university hospital. Patients were followed for the development of acute renal failure (defined as a calculated creatinine clearance of 50 ml/min or less) within the first 7 postoperative days. Patient preoperative characteristics and intraoperative anesthetic management were evaluated for associations with acute renal failure. Thirty-day, 60-day, and 1-yr all-cause mortality was also evaluated. Results:A total of 65,043 cases between 2003 and 2006 were reviewed. Of these, 15,102 patients met the inclusion criteria; 121 patients developed acute renal failure (0.8%), and 14 required renal replacement therapy (0.1%). Seven independent preoperative predictors were identified (P < 0.05): age, emergent surgery, liver disease, body mass index, high-risk surgery, peripheral vascular occlusive disease, and chronic obstructive pulmonary disease necessitating chronic bronchodilator therapy. Several intraoperative management variables were independent predictors of acute renal failure: total vasopressor dose administered, use of a vasopressor infusion, and diuretic administration. Acute renal failure was associated with increased 30-day, 60-day, and 1-yr all-cause mortality. Conclusions:Several preoperative predictors previously reported to be associated with acute renal failure after cardiac surgery were also found to be associated with acute renal failure after noncardiac surgery. The use of vasopressor and diuretics is also associated with acute renal failure.

Surgical Site Infection Prevention: The Importance of Operative Duration and Blood Transfusion—Results of the First American College of Surgeons–National Surgical Quality Improvement Program Best Practices Initiative

BACKGROUND Surgical site infections (SSI) continue to be a significant problem in surgery. The American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) Best Practices Initiative compared process and structural characteristics among 117 private sector hospitals in an effort to define best practices aimed at preventing SSI. STUDY DESIGN Using standard NSQIP methodologies, we identified 20 low outlier and 13 high outlier hospitals for SSI using data from the ACS-NSQIP in 2006. Each hospital was administered a process of care survey, and site visits were conducted to five hospitals. Comparisons between the low and high outlier hospitals were made with regard to patient characteristics, operative variables, structural variables, and processes of care. RESULT Hospitals that were high outliers for SSI had higher trainee-to-bed ratios (0.61 versus 0.25, p < 0.0001), and the operations took significantly longer (128.3+/-104.3 minutes versus 102.7+/-83.9 minutes, p < 0.001). Patients operated on at low outlier hospitals were less likely to present to the operating room anemic (4.9% versus 9.7%, p=0.007) or to receive a transfusion (5.1% versus 8.0%, p=0.03). In general, perioperative policies and practices were very similar between the low and high outlier hospitals, although low outlier hospitals were readily identified by site visitors. Overall, low outlier hospitals were smaller, efficient in the delivery of care, and experienced little operative staff turnover. CONCLUSIONS Our findings suggest that evidence-based SSI prevention practices do not easily distinguish well from poorly performing hospitals. But structural and process of care characteristics of hospitals were found to have a significant association with good results.

Preoperative and intraoperative predictors of cardiac adverse events after general, vascular, and urological surgery.

Background:The authors sought to determine the incidence and risk factors for perioperative cardiac adverse events (CAEs) after noncardiac surgery using detailed preoperative and intraoperative hemodynamic data. Methods:The authors conducted a prospective observational study at a single university hospital from 2002 to 2006. All American College of Surgeons–National Surgical Quality Improvement Program patients undergoing general, vascular, and urological surgery were included. The CAE outcome definition included cardiac arrest, non-ST elevation myocardial infarction, Q-wave myocardial infarction, and new clinically significant cardiac dysrhythmia within the first 30 postoperative days. Results:Four years of data demonstrated that of 7,740 noncardiac operations, 83 patients (1.1%) experienced a CAE within 30 days. Nine independent predictors were identified (P ≤ 0.05): age ≥ 68, body mass index ≥ 30, emergent surgery, previous coronary intervention or cardiac surgery, active congestive heart failure, cerebrovascular disease, hypertension, operative duration ≥ 3.8 h, and the administration of 1 or more units of packed red blood cells intraoperatively. The c-statistic of this model was 0.81 ± 0.02. Univariate analysis demonstrated that high-risk patients experiencing a CAE were more likely to experience an episode of mean arterial pressure < 50 mmHg (6% vs. 24%, P = 0.02), experience an episode of 40% decrease in mean arterial pressure (26% vs. 53%, P = 0.01), and an episode of heart rate > 100 (22% vs. 34%, P = 0.05). Conclusions:In comparison with current risk stratification indices, the inclusion of intraoperative elements improves the ability to predict a perioperative CAE after noncardiac surgery.

An anesthesia information system designed to provide physician-specific feedback improves timely administration of prophylactic antibiotics.

Surgical site infections are a frequent cause of morbidity and mortality and add significantly to the cost of care. One component of the national Surgical Infection Prevention (SIP) program is to ensure timely administration of prophylactic antibiotics, a key factor to reduce postoperative infection. Our anesthesia department decided to assume the responsibility for timing and administration of antibiotic prophylaxis and we initiated a multitiered approach to remind the anesthesiologist to administer the prophylactic antibiotics. We used our anesthesia clinical information system to implement practice guidelines for timely antibiotic administration and to generate reports from the database to provide specific feedback to individual care providers with the goal of ensuring that patients receive antibiotic prophylaxis within 1 h of incision. Before the initiation of this project, 69% of eligible patients received antibiotics within 60 min of the incision. After the program began, there was a steady increase in compliance to 92% 1 yr later. Provider-specific feedback increases compliance with practice guidelines related to timely administration of prophylactic antibiotics. Anesthesia information systems hold promise for implementing and monitoring new practice guidelines and the anesthesiologist may play a key role in influencing surgical outcomes by ensuring appropriate therapy that may not be directly related to anesthesia care.

Grading scale for mask ventilation

To the Editor:—One of the most important aspects of airway management is the ability to mask ventilate a patient. Although there are methods to assess the probability of the difficulty of intubation and grading the view during laryngoscopy, there is, to our knowledge, no recognized scale to grade mask ventilation. Langeron et al. investigated factors predictive of difficult mask ventilation. They found that the incident of difficult mask ventilation was 5% of all cases and was associated with five criteria: age older than 55 yr, body mass index greater than 26 kg/m, lack of teeth, presence of a beard, or history of snoring. In this study, they rated mask ventilation as difficult when the clinician considered it “clinically relevant and could have led to potential problems if mask ventilation had to be maintained for a longer time.” They rated mask ventilation as impossible “when it completely failed and an alternative technique of ventilation was required in emergency conditions.” This study did not define a grading scale other than “difficult” and “impossible.” In an accompanying editorial, Adnet did recommend that a grading scale be developed. The American Society of Anesthesiologists Guidelines for Management of the Difficult Airway defines difficult facemask ventilation as the situation in which “it is not possible for the anesthesiologist to provide adequate face mask ventilation due to one or more of the following problems: inadequate mask seal, excessive gas leak, or excessive resistance to ingress or egress of gas.” The guidelines also describes the signs of an inadequate facemask ventilation, but again, there is no proposed grading system for the ability to facemask ventilate. During the development of a perioperative information system, we found it useful to devise a grading system similar to that used for grading the view during laryngoscopy. Initially, we chose grades 0–4, defined in table 1. There was also a means by which practitioners could type in a text description of mask ventilation. The incidence of each grade of ease or difficulty with mask ventilation is described in table 1. Institutional review board approval was received for this electronic chart review process. After approximately 3 weeks, we compiled the results of documentation using the selections chosen (table 1). On review of these data, we revised the definitions of the grading as described in table 2, removing the modifiers of “easy” and “difficult” before grades 1 and 2. After another 3 weeks, these data were again compiled with the results in table 2. The second version of the grading system resulted in similar percentages for both grade 3 and grade 4, a reduction in grade 1, and an increase in grade 2 classifications. We also noted a substantial decrease in the number of comments going from 1.4% to 0.3% of cases. We believed that the reduction in comments implied that the second method of defining the grades of mask ventilation was easier to select for the practitioners, although it may have been because individuals were more used to the system, in general. As with the grading of airway evaluation and view of laryngoscopy, grading the ability to mask ventilate is subjective and practitioner dependent. It is interesting to note that Langeron et al. reported one case of impossible to ventilate out of the 1,502 patients, whereas we noted three in 2,621 cases. This close agreement in the incidence of being unable to ventilate was probably because being unable to ventilate a patient is a more objective (and memorable) event. We did not find as close an agreement in patients who were defined as “difficult mask ventilation” (grade 3). Langeron et al. found this in 5% of their patients, whereas we noted an incidence of 1.3%. This may be because Langeron et al. had a broader definition of difficult mask ventilation. Ultimately, the most important grades to document are the more difficult ones, grades 3 and 4, because those would most likely affect the plan for future anesthetics. We have continued with the classifications and descriptions presented in table 2 and have found this information useful for planning future anesthetics, especially for patients in whom intubation was difficult.

Immunopathologic responses to non-lethal sepsis.

Although sepsis causes significant morbidity and mortality, its basic pathology is still not well understood. We investigated the inflammatory and physiologic alterations of non-lethal sepsis using cecal ligation and puncture (CLP), a model that induces peritonitis due to mixed intestinal flora, reproducing the complex immunology of sepsis. Groups of mice were subjected to CLP (25G needle) or sham surgery, had minimitters implanted to continuously monitor temperature and activity, and were sacrificed daily for 6 days. There was significant hypothermia (6-13 hrs post-surgery), and decreases in activity (to day 4) and weight (to day 3) but no mortality in the CLP group. Blood analyses of the CLP-treated mice showed reduced hemoglobin, platelets, lymphocytes, monocytes, and neutrophils, compared to sham animals. Both groups had nearly equivalent neutrophil influx into the peritoneum. Plasma and peritoneal G-CSF, IL-6, as well as the murine chemokines KC and MIP2-alpha were significantly higher in the CLP-treated mice at day 1. Plasma and peritoneal TNF were low (<70 pg/mL). While there was elevated IL-1beta in the peritoneum of the CLP-treated mice, this cytokine was not detected in the plasma in either treatment group. Cytokines were not detected in the pulmonary airspace of the CLP-treated mice and PMNs were not recruited to this site. Our data shows altered immunopathology in non-lethal sepsis with significant blood and cytokine alterations. Since there was 100% survival, the inflammatory response was appropriate and probably even protective.

Life-threatening critical respiratory events: a retrospective study of postoperative patients found unresponsive during analgesic therapy

STUDY OBJECTIVE To identify risk factors for life-threatening critical respiratory events occurring during parenteral analgesic therapy for acute postoperative pain. DESIGN Retrospective, observational, cohort study. SETTING University hospital. MEASUREMENTS The electronic records of patients with sudden-onset, life-threatening critical respiratory events during analgesic therapy for postoperative pain were studied. Critical respiratory event data were identified from the hospital risk management database between 8/1/2000 and 7/31//2007. Patients required rescue treatment with naloxone, endototracheal intubation, or cardiopulmonary resusucitation. Pediatric patients were excluded from the study. In addition to the event description (type of analgesia, opioid dose, patient monitoring data, time of day, and time from surgery), each patients record was reviewed to extract co-morbidities and outcome data. MAIN RESULTS Over the 6-year period, 32 patients experienced a postoperative critical respiratory event. Twenty-six events and three deaths occurred within the first 24 hours of opioid therapy. Four of 32 patients died. Congestive heart failure, postoperative acute renal failure, obstructive sleep apnea, cardiac dysrhythmia, diabetes mellitus, coronary artery disease, and hypertension were significant associations in adult patients. CONCLUSIONS The first 24 hours after commencing opioid-based analgesic therapy represents a high risk period. Obstructive sleep apnea, deep levels of sedation, nocturnal presentation, and postoperative acute renal failure were seen in patients who died as a result of these critical respiratory events.

Electronic reminders improve procedure documentation compliance and professional fee reimbursement.

BACKGROUND:Medicolegal, clinical, and reimbursement needs warrant complete and accurate documentation. We sought to identify and improve our compliance rate for the documentation of arterial catheterization in the perioperative setting. METHODS:We first reviewed 12 mo of electronic anesthesia records to establish a baseline compliance rate for arterial catheter documentation. Residents and Certified Registered Nurse Anesthetists were randomly assigned to a control group and experimental group. When surgical incision and anesthesia end were documented in the electronic record keeper, a reminder routine checked for an invasive arterial blood pressure tracing. If a case used an arterial catheter, but no procedure note was observed, the resident or Certified Registered Nurse Anesthetist assigned to the case was sent an automated alphanumeric pager and e-mail reminder. Providers in the control group received no pager or e-mail message. After 2 mo, all staff received the reminders. RESULTS:A baseline compliance rate of 80% was observed (1963 of 2459 catheters documented). During the 2-mo study period, providers in the control group documented 152 of 202 (75%) arterial catheters, and the experimental group documented 177 of 201 (88%) arterial lines (P < 0.001). After all staff began receiving reminders, 309 of 314 arterial lines were documented in a subsequent 2 mo period (98%). Extrapolating this compliance rate to 12 mo of expected arterial catheter placement would result in an annual incremental

Anesthesia Information Management System Implementation: A Practical Guide

40,500 of professional fee reimbursement. CONCLUSIONS:The complexity of the tertiary care process results in documentation deficiencies. Inexpensive automated reminders can drastically improve compliance without the need for complicated negative or positive feedback.