Does cerebral oximetry always measure brain tissue oxygen saturation? An anatomical study utilizing computed tomography.

Background and Aims: to quantify the scalp-cortex distance and determine its variation among patients. We hypothesized that in a significant number of patients, this distance is greater than the maximum penetration depth of current cerebral oximeters. Material and Methods: A retrospective anatomic study using transverse head CT images selected randomly from 102 patients over the age of 18 years without brain swelling, intracranial mass effect, or brain hemorrhage. Scalp-cortex distances were determined at two separate locations along the craniocaudal axis; most cephalad to the frontal sinus (I0) and also 2 cm cephalad to that location (I2). Multiple measurements were obtained bilaterally at 1, 3, 5, 7, and 9 cm from midline. Results: The average scalp-cortex distance was 14.3 mm and 15 mm at I0 and I2 respectively. Distances varied more in I2 than in I0; from the measurements, 12.8% vs. 6.8% were over 20 mm, 4.4% vs. 2.2% over 25 mm, 1.1% vs. 0.6% over 35 mm and 0.6% vs. none over 40 mm at I2 and I0, respectively. 1.5% of the measurements at I2 were over 30 mm. Conclusion: Cerebral oximetry manufacturers all claim to measure cerebral tissue up to a depth of 20-25 mm; 20 mm with the EQUANOX and INVOS compared with 25 mm with the FORE-SIGHT. Scalp-cortex distance is within 25 mm in more than 95% of patients. However, even with the probe placed as per the manufacturer's recommendations, in a small but significant subset of patients, this distance is greater than the maximum penetration depth of current cerebral oximeters and hence may not reflect actual brain tissue oxygen saturation.

An Unusual Cause of Failure to Ventilate.

We report an unusual case of endotracheal tube failure. It was due to a manufacturing defect in the internal white plastic piece that is normally depressed by the luer-lock syringe within the blue pilot balloon. Prior to use, the endotracheal tube was tested and functioned normally. A 64-year-old patient in the intensive care unit with a history of hypertension was being mechanically ventilated after uneventful abdominal surgery. After several hours in the intensive care unit, he was noted to be suddenly no longer receiving adequate tidal volumes from the ventilator. It was found that the cuff on the endotracheal tube was not retaining air when it was filled with air from a syringe. This lead to a large "leak" around the endotracheal tube such that the intended tidal volumes set on the ventilator were not delivered to the patient. The patient was uneventfully reintubated and did well. Subsequent investigation revealed the cause to be a manufacturing defect in the internal white plastic piece that is normally depressed by the luer-lock syringe within the blue pilot balloon. Other mechanisms of cuff failure are reviewed in this case report. This case is an unusual reason for cuff failure. Illustrations supplied alert the reader how to identify the appearance of this manufacturing defect in a pilot balloon. This case illustrates the potential device malfunctions that can develop during a procedure, even when the equipment has been tested and previously functioned well. Even small defects developing in well-engineered products can lead to critical patient care emergencies.

Varicella Pneumonia: Case Report and Review of a Potentially Lethal Complication of a Common Disease.

Varicella zoster virus causes varicella (chickenpox). It can be reactivated endogenously many years later to cause herpes zoster (shingles). Although varicella is usually a benign disease in healthy children, it resulted in over 11 000 hospitalizations and over 100 deaths every year, in all ages, in the United States. Morbidity was considerably worse in older teenagers and adults. Between 5% and 15% of cases of adult chickenpox will produce some form of pulmonary illness. Progression to pneumonia risk factors include pregnancy, age, smoking, chronic obstructive pulmonary disease, and immunosuppression. Typically, pulmonary symptoms occur 1 to 6 days after varicella zoster infection. They often include cough, fever, and dyspnea. Treatment is a 7-day course of intravenous acyclovir for varicella pneumonia. Early intervention may modify the course of this complication. This review illustrates practical features with a case of a 34-year-old female with severe varicella pneumonia. Despite the lack of significant past medical history and absence of immunosuppression, her pneumonia worsened and by using continuous positive airway pressure mask, intubation was avoided. More important, the radiographic progression of severe varicella pneumonia is shown. This highlights how a common disease of varicella can progress in an adult and manifest with significant organ malfunction.

Near-fatal kinking of mammary graft due to emphysematous lung disease.

Left internal mammary artery grafting is commonly used in elective coronary artery bypass graft surgery. We report a near-fatal case with graft kinking upon sternal closure due to distended, emphysematous lungs impinging on the mammary graft. After the sternum was closed, the patient suffered a severe hemodynamic deterioration. Surgical examination revealed kinking of his left internal mammary artery upon sternal closure due to distended, emphysematous lungs impinging on the mammary graft. Using an off-bypass technique, the kink in the mammary graft to the left anterior descending artery was removed by moving the origin of the left internal mammary artery to a hooded graft of a saphenous vein graft instead. In this position, the graft no longer was impinged upon by the distended emphysematous lungs. Subsequently, the patient's sternum was closed without hemodynamic impingement. Although chronic obstructive pulmonary disease is well described to increase complications in coronary artery bypass graft surgery, it has not been previously associated with the kinking of a left internal mammary artery. This report highlights another contribution that chronic obstructive pulmonary disease can make to increased morbidity following coronary artery bypass graft surgery and alerts readers to watch for this complication in susceptible patients.

Hospital initiatives in promoting smoking cessation: A 12-year follow-up.

In the present study, the availability of smoking cessation programs (SCP) was surveyed in the same randomly selected USA hospitals in 2000 and 2012. A total of 102 USA hospitals were randomly selected for this survey. Each hospital website was searched for the topic of smoking cessation. In the second phase of the survey, the main switchboard number of each hospital was anonymously telephoned and the 'stop smoking clinic' was requested. The phone survey results showed that the percentage of hospital switchboard calls that were connected to a SCP remained identical at 47% in 2000 and 2012. The results for the internet availability of SCP on hospital websites improved from 30% in 2000 to 47% in 2012. There were more hospitals that added additional SCP information (27%) compared with those that removed SCP information (15%) by 2012. Among the 57% of hospitals that showed no change in internet SCP information, 22% remained positive for such information while 35% remained negative. The phone survey of hospitals showed that 47% of USA hospitals were able to connect a caller to a SCP in the years 2000 and 2012. While there was no reduction over the 12 years, there was no increase in the percentage of hospital switchboards that connected to a SCP. Availability of SCP information on hospital web sites improved to a limited extent; increasing from 30% of sites in 2000 to 47% in 2012. Providing SCP on a hospital website is easy and free, for example adding a link to QuitNet or QuitLink. The present study adds to information gathered 12 years earlier, and is unusual in being able to provide follow-up data on the same set of hospitals studied previously.

Ropivacaine 0.025% mixed with fentanyl 3.0 µg/ml and epinephrine 0.5 µg/ml is effective for epidural patient-controlled analgesia after cesarean section.

BACKGROUND AND AIMS: We aimed to determine the ropivacaine concentration that provided adequate analgesia with early ambulation and minimal urinary retention or other side-effects when used with fentanyl and epinephrine for patient-controlled epidural analgesia (PCEA) after elective cesarean section. MATERIAL AND METHODS: Forty-eight patients were randomized to four groups in a double-blinded fashion. All groups received an initial 10 ml/h of epidural study solution for 24 h. The solution contained: 0.2, 0.1, 0.05, or 0.025% ropivacaine for Groups I-IV, respectively, with fentanyl 3.0 µg/ml and epinephrine 0.5 µg/ml. Patients could administer additional PCEA doses of 4 ml of their study solution with a lock-out time of 10 min. Overall satisfaction, side-effects, motor block, neurologic function, and pain using Visual Analog Scale were assessed. RESULTS: Patients in all groups showed no difference in sedation, pruritus, nausea, vomiting, and uterine cramps. Pain scores at rest were lower for Group IV than Groups I-III (P < 0.001). Twelve, five, one, and zero patients could not ambulate in Groups I-IV, respectively. Nine, nine, two, and zero (III

Cerebral Oximetry Decrease After External Carotid Clamping with Normal Electroencephalography and No Change After Internal Carotid Clamping.

Monitoring of cerebral perfusion by near-infrared spectroscopy estimates regional cerebral oxygen saturation (rSO2). We present a case in which, before clamping the left carotid artery during an endarterectomy, the right and left rSO2 measurements were 72% and 74%, respectively. Within 15 seconds of clamping the external carotid artery, the left rSO2 decreased by 8%, yielding right and left rSO2 measurements of 70% and 66%, respectively. No electroencephalogram changes ensued. The internal carotid artery was clamped 1 minute later, whereas the external carotid remained clamped. No electroencephalogram changes were observed. The rSO2 measurements demonstrate that the value of this cerebral oximetry is not determined solely from internal carotid blood flow and can be significantly affected by the external carotid.

Methylene blue treatment for cytokine release syndrome-associated vasoplegia following a renal transplant with rATG infusion: A case report and literature review.

Rabbit anti-thymocyte globulin (rATG) is an infusion of polyclonal rabbit-derived antibodies against human thymocyte markers, which can be used to prevent and treat acute rejection following organ transplantation. However, the product monograph issued by the manufacturer (Sanofi Canada) reports that serious immune-mediated reactions have been observed following the use of rATG, consisting of anaphylaxis or severe cytokine release syndrome (CRS), which is a form of vasoplegic syndrome (VS), in which distributive shock occurs refractory to norepinephrine (NE) and vasopressin (VP). Severe infusion-associated reactions are consistent with CRS and can cause serious cardiac or respiratory problems, or in certain cases, mortality. CRS is a form of systemic inflammatory response syndrome (SIRS). In SIRS, the substantial activation of endothelial inducible nitric oxide synthase (iNOS) and smooth muscle guanylate cyclase (GC) is observed, which can produce severe hypotension that is unresponsive to conventional vasopressors. Methylene blue (MB) is a direct inhibitor of iNOS and GC and has been used as an effective treatment for VS following cardiothoracic surgery. In the present study, the successful use of MB as a rescue therapy for CRS in a patient receiving rATG following a renal transplant was reported. Following an uneventful cadaveric kidney transplant involving the intravenous (IV) administration of rATG for the induction of immunological tolerance, the patient became markedly hypotensive and tachycardic. The patient required high doses of VP and NE infusions. Following the protocol described for treating refractory VS in post-cardiac surgery patients, the decision was made to initiate the patient on an IV MB infusion. This treatment protocol was shown to improve the hemodynamic status of the patient, which enabled the withdrawal of vasopressors and suggests an important role for methylene blue in the management of refractory VS.

A new technique for avoiding barotrauma-induced complications in apnea testing for brain death.

Prompted by our experience with complications occurring with apnea testing (AT), we discuss complications reported in the literature. AT is an integral part of brain death assessment. Many complications of AT have been described, including hypoxemia, arterial hypotension, tension pneumothorax and cardiac arrest. We conclude that a commonly used technique in conducting AT can create auto-positive end expiratory pressure (PEEP) and contributes to many complications. The mechanism of occult auto-PEEP in AT is discussed. Intensive care unit patients may have a compensated and asymptomatic relative hypovolemia that can be decompensated by a small amount of auto-PEEP produced by air trapping during insufflating oxygen (O2) through a 7.0 endotracheal tube (ETT). It could then lead to decreased preload, decreased stroke volume, decreased cardiac output and thus, to hypotension and a compensatory tachycardia. The placement of the standard O2 tubing (6mm outside diameter [OD]) inside the 7.0 ETT (7mm inside diameter [ID]) greatly decreased the ETT lumen (73%). We changed our practice to instead use readily available small pressure tubing to insufflate O2 for AT to avoid excessive reduction in the ETT lumen. The change from standard O2 tubing (6mm OD) to pressure tubing (3mm OD) will greatly decrease the reduction in cross-sectional area of 7.0 ETT lumen from 73 to 18% and avoid potential complications of air trapping, auto-PEEP and barotrauma. We have successfully used this new simple technique with readily available equipment to eliminate auto-PEEP in AT while preserving oxygenation.

Lower incidence of hypo-magnesemia in surgical intensive care unit patients in 2011 versus 2001.

BACKGROUND: Hypo-magnesemia is described to occur in as many as 65% of intensive care unit (ICU) patients. Magnesium (Mg) is a cofactor in over 300 enzymatic reactions involving energy metabolism, protein, and nucleic acid synthesis. The membrane pump that creates the electrical gradient across the cell membrane is dependent on Mg, and it is important in the activity of electrically excitable tissues. Since Mg regulates the movement of calcium in smooth muscle cells, it is also important in peripheral vascular tone and blood pressure. Studies have linked hypo-magnesemia to multiple chronic diseases and to a higher mortality rate. METHODS: To explore trends within our own tertiary care surgical ICU, we sampled our patients' laboratory records in 2001 and in 2011. Hypo-magnesemia in our ICU is defined as an Mg less than 2.0 mg/dL. RESULTS: This retrospective review of all SICU patients from October to December revealed that there was a significant increase (P < 0.01) in the patients with their serum Mg level measured between 2001 (89%) and 2011 (95%). There was a significant decrease (P < 0.001) in patients with hypomagnesemia (< 2 mg/dL) between 2001 (47.5%) and 2011 (33.0%). On the other hand, there was a significant increase (P < 0.001) in patients with normal serum Mg level (> 2 mg/dL) between 2001 (52.5%) and 2011 (67.0%). CONCLUSIONS: There was not only more monitoring of Mg in 2011, but a lower incidence of hypo-Mg compared to 2001. Possible explanations include changing patterns of antibiotic and diuretic use, less amphotericin use, more frequent laboratory surveillance, and better trained ICU practitioners.

Increasing severity of aortic atherosclerosis in coronary artery bypass grafting patients evaluated by transesophageal echocardiography.

BACKGROUND: Atherosclerotic disease in coronary artery bypass grafting (CABG) patients is a potential contributor to complications in the perioperative periods. This study was undertaken to better define how the frequency of aortic atheromatous disease among patients coming for CABG has evolved over the last decade. METHODS: Data from elective patients coming for CABG who underwent transesophageal echocardiography (TEE) examinations following induction of anesthesia were obtained for the years 2002 and 2009. Aortas were graded according to the method of Kronzon, with the following interpretations: normal = grade I, intimal thickening = 2, atheroma of less than 5 mm = 3, atheroma of > 5 mm = 4, and any mobile atheroma = 5. The data of 124 patients who underwent comprehensive exam of the aorta by one cardiac anesthesiologist were gathered and assigned into two groups based on the year TEE was done. Student's t-test was used for statistical analysis. A P value < 0.05 was considered significant. The data were presented as mean ± SD. RESULTS: There was significant difference between group 2002 (2.05 ± 1.28) and group 2009 (2.59 ± 1.11) in atheroma grade (P = 0.013). CONCLUSIONS: Patients coming for CABG in group 2009 exhibited significantly higher grades of aortic atheroma on TEE, compared to group 2002. Understanding the risk of atheroma in the elderly CABG population may help in altering surgical approaches to lessen the risk of catastrophic stroke. Potential options needing further study include the off-pump approach and modification of cross-clamp site and technique as well as other modalities.

Preventing "a bridge too far": promoting earlier identification of dislodged dental appliances during the perioperative period.

The presence of fixed partial dentures presents a unique threat to the perioperative safety of patients that require orotracheal intubation or placement of instruments into the gastrointestinal (GI) tract. There are many chances for the displacement of a fixed partial denture: instrumentation of the airway for intubation, or introduction of temporary devices, such as gastroscopes or transesophageal echo probes. If dislodged, the fixed partial dentures can enter the hypopharynx, esophagus or lungs and cause perforations with their sharp tines. Oral or esophageal perforation can lead to potentially fatal mediastinitis. We describe a case of a patient with a fixed partial denture who underwent cardiac surgery with intubation and transesophageal echocardiography (TEE). His partial denture was intact after the procedure. After extubation, he reported that his teeth were missing. Multiple procedures were required to remove his dislodged partial dentures. In sign-out reports, verbal descriptions of the patient's partial dentures were not adequate in this case. A picture of the patient's denture and oral pharynx pre-operatively would have provided a more accurate template for the post-operative team to refer to when caring for the patient. This may have avoided the multiple potentially risky procedures the patient had to undergo. We describe a suggested protocol utilizing a pre-operative photo to reduce the incidence of unrecognized partial denture dislodgement in the perioperative period. Because the population is aging, this will become a more frequent issue confronting practitioners. This protocol could mitigate this complication.

Novel configuration of laryngeal mask airway.

OBJECTIVES: Hospital airway emergency teams are often responsible for responding to codes, emergency intubations etc. The individual provider may have to respond quickly to widely separated areas of large medical centers on a moment's notice. Further, in addition to the urgency, the distance of different sites makes it important that the airway team not have to lug a large medical gear bag with airway supplies and emergency drugs. While the importance of the LMA in emergency airway management has been well established, it is sold as a fairly bulky device that requires a disproportionate space in an airway pack. We sought to examine whether modifying the LMA packaging might reduce the amount of space taken up by the need to carry three different sizes in an airway pack. METHODS: A commonly used Laryngeal Mask Size Number 3 manufactured by Ambu Company was studied. The volume displacement of the package, and then just the LMA was measured using volumetric techniques. RESULTS: Removing the large packaging yielded a much smaller footprint in cubic ml that was only 18% of the original packaging: 43 versus 240 cubic milliliters. CONCLUSIONS: This configuration of LMA transport allows for transporting more airway equipment in less space. These results have important implications for emergency airway response teams. Removing the original packaging and using this folded-over configuration allows to use 82% less volume in cubic milliliters per LMA in the airway pack. This allows emergency teams to carry more equipment in much less space.

The Swan-Ganz catheter as a teaching tool for the anesthesiologist learning minimally invasive cardiac surgery.

OBJECTIVE: To perform minimally invasive cardiac surgery through the smallest possible wound and with the least number of incisions in the heart or aorta, the necessary cannulations to undergo cardiopulmonary bypass must be done through peripheral vessels. A difficult skill to learn for the cardiac anesthesiologist is how to safely and efficiently position the coronary sinus catheter (Endoplege; Edwards Lifesciences LLC, Irvine, CA USA) required for retrograde cardioplegia administration. METHODS: In patients in whom a Swan-Ganz catheter was inserted as part of the operative management strategy for non-minimally invasive heart surgery, we have been using it as a training tool to learn how to visualize and manipulate right-sided catheters under transesophageal echocardiography. We developed this teaching technique to help hone some of the necessary skills needed to place the Endoplege catheter for minimally invasive cardiac surgery. Manipulation was done with the goal of visualizing the catheter and guiding it into the coronary sinus. For a 4-month period, anesthesia records were retrospectively reviewed. RESULTS: Fifteen patients, for a total of 19 catheter manipulations, were found in whom we had documented the use of the Swan-Ganz catheter and details about the insertion as a training tool. The coronary sinus and the catheter were visualized 100% of the time. The Swan-Ganz catheter was successfully inserted into the coronary sinus in 17 of 19 catheter manipulations. CONCLUSIONS: The Swan-Ganz catheter can be used as a training tool to develop some of the necessary skills to place catheters into the coronary sinus with transesophageal echocardiography guidance.

Cannulation of the middle cardiac vein during MICS.

Coronary sinus cannulation for retrograde cardioplegia administration during cardiac surgery is common practice. Several of the cannulas that are placed by the cardiac surgeon on open procedures are now placed by the cardiac anesthesiologist during minimally invasive cardiac surgery, including the coronary sinus catheter. The understanding of the cardiac venous anatomy is very important during coronary sinus catheter placement. We present a case where a percutaneously placed coronary sinus catheter was inadvertently placed into the middle cardiac vein but detected with the use of fluoroscopy.

Hospital initiatives in promoting smoking cessation: a survey of Internet and hospital-based programs targeted at consumers.

STUDY OBJECTIVES: This study assesses how often local US hospitals provide smoking cessation information in the following two ways: via hospital Web sites; and via routing incoming phone calls to their hospital switchboards to an in-house smoking cessation clinic. DESIGN: Random survey of US hospitals. SETTING: US hospital Web pages and telephone switchboards. PATIENTS OR PARTICIPANTS: One hundred two randomly selected US hospitals. INTERVENTIONS: One hundred two hospital Web sites were randomly selected across the United States. The site was searched for the topic of smoking cessation. In the second phase of the survey, the main switchboard number of the same 102 hospitals was anonymously called and the "stop smoking clinic" was asked for. MEASUREMENTS AND RESULTS: The overall results indicate that among the hospital Web sites surveyed, only 30% contained information relating to smoking cessation programs. The phone survey of hospital switchboards showed that 47% had a smoking cessation program available via phone inquiry, while 53% did not. CONCLUSIONS: Of the US hospital Web sites visited, only 30% contained information on smoking cessation. The yield of finding the desired information was increased by the presence of an intrasite search option, which is a low-cost enhancement to any complex Web site. The relatively low cost of promoting healthy behaviors such as smoking cessation on a hospital Web site should be used more widely. Surprisingly, the phone survey of hospitals showed that the lower technology route of providing smoking cessation information to patients via a patient-initiated phone call is only available in 47% of hospitals. Both the Internet and phone-based switchboard referrals could be more widely and effectively used. Joint Commission on Accreditation of Healthcare Organizations guidelines would be one avenue of increasing the availability of smoking cessation information at hospital switchboards and Web sites.