Dept Of Anesthesiology & Critical Care, University Of Pennsylvania School Of Medicine

Race and socio – economic status influence acceptance of post operative epidural analgesia

Ochroch and associates (Anesth Analg 2007;105:1787) used a survey of patients scheduled for elective surgery to determine rates of acceptance of post operative epidural analgesia.  Over a four month period a trained research technician contacted the patients the day prior to their scheduled admission and then conducted a standard survey by telephone.  3739 patients were called at home, 1265 were contacted and 1193 consented to participate in the study.  64% of the study participants said that they would accept an epidural if recommended by an anesthesiologist and 36% said they would refuse.  The rate of acceptance increased to 78% if the epidural was recommended by both the surgeon and anesthesiologist with 22.5% still refusing.  A univariate logistic regression showed that patients with higher incomes, more education and who where employed full or part time were more likely to accept an epidural.  African Americans were far less likely then Caucasians to accept an epidural.  When controlling for gender, education level, employment type income and marital status, African American race predicted refusal of epidural analgesia. (OR 0.58, 95 % 0.32 – 0.78)  The authors attempted to determine some of the reasons for refusal but were unable to do so.  Of concern then is a group of patients who for some reason absent themselves from a proven form a post operative pain therapy that may have benefits with respect to reduced pain and improved recovery.  Of interest, from my observations, is the high acceptance of epidural analgesia on the HUP labor floor in a patient population that has a large number of African Americans (DSS comment).

Edward Andrew Ochroch M.D., MSCE is Associate Professor of Anesthesiology and Critical Care at the Hospital of the University of Pennsylvania

David S. Smith, M.D., Ph.D.

A proposed mechanism for isoflurane induced apoptosis

Wei and associates continue their investigations into isoflurane toxicity in this paper from Anesthesiology (2008;108:251 – 260).  Using a variety of cultured cell types they showed that isoflurane activates the endoplasmic reticulum membrane inositol 1,4,5-triphosphate (IP3) receptor.  This activation produces excessive calcium first in the cytosol and then in mitochondria.  It is this higher calcium level that triggers apoptosis.  There was considerable variability in the sensitivity of the various cell lines to isoflurane induced apoptosis.  The authors note that certain cases of familial Alzheimer’s or Huntington disease have enhanced IP3 receptor activity and thus may be more sensitive to the toxic effects of isoflurane.  Recognize the difficulty of extrapolating from cell cultures, to organs or whole animals.  Thus, it is my belief, that further work is necessary before clinical practice is altered by findings such as these (DSS comment).

Huafeng Wei, M.D., Ph.D. is Assistant Professor of Anesthesiology and Critical Care at the University of Pennsylvania

David S. Smith, M.D., Ph.D.

Risk for thromboembolism in hospitalized patients is high; the rate of appropriate prophylaxis is far too low

A recent paper and an editorial in the Lancet discussed the high rate of complications from venous thromboembolism (VTE) in both surgical and medical hospitalized patients and the relatively low rate of VTE prophylaxis.  They note that pharmacological prophylaxis reduces the risk of pulmonary embolism in general surgical patients by 75% and by 57% in medical patients.  However a cross sectional survey of nearly 70,000 hospitalized patients in 32 countries revealed that though 66% of surgical patients and 40% of medical patients were eligible for VTE prophylaxis only 59% and 40% of the at risk patients received this potentially lifesaving therapy.  Data from United States Centers appeared better than the overall.  Of the at risk surgical patients 80% were receiving some sort of prophylaxis and 71% were receiving the American College of Chest Physicians recommended prophylaxis.  However only 64% of at risk medical patients were receiving any sort of prophylaxis.  From 1) Cohen AT et al: Venous thromboembolism risk and prophylaxis in the acute hospital care setting (ENDORSE study); a multinational cross-sectional study.  Lancet 2008;371:381- 394 2) Ageno W, Dentali F: Prevention of in-hospital VTE: why can’t we do better? Lancet 2008;371:361-362

David S. Smith, M.D., Ph.D.

Coagulopathy and tranfusion

A low ratio of fresh frozen plasma to RBCs decreases mortality in patients receiving massive transfusions at a combat support hospital (Borgmann MA et al, J Trauma 2007;63:805 – 813).  The authors performed a retrospective review of the records from 246 soldiers with combat injuries who received massive transfusions (> 10 units of RBC in 24 h).  In the paper’s introduction the authors note that about 5% of patients admitted to Iraq US combat support hospitals require massive transfusion.  They note that mortality rates among these patients is more than 30% and that a considerable portion of this mortality appears related to the lethal triad of hypothermia, metabolic acidosis and coagulopathy.  Penetrating injuries were present in 94% of the group, 1% of the injured were female, and the median age was 24.  The median injury severity score (ISS) was 18 and the overall mortality was 28%.  The authors used a statistical process to divide the group into low, medium and high plasma to RBC groups with the low group having a plasma to RBC ratio of 1:8, the medium having a ratio of 1:2.5 and high with a ratio of 1:1.4.  Mortality decreased as the ratio of fresh frozen plasma to RBCs increased with a mortality of 65% in the low, 34% in the medium and 19% in the high group.  With respect to primary cause of death, hemorrhage related death was less in the high ratio group (37%) compared to the low ratio group (92.5%) producing a relative reduction of 60%.  The authors concluded that for patients with significant traumatic injuries requiring massive transfusion survival improved when fresh frozen plasma and RBCs are administered in near equal volumes (a ratio of 1:1.4).  The authors noted that those patients who received large amounts of fresh frozen plasma early required less total fluid in the first 24 hours.  They also noted that those in the low or medium plasma to RBC ratio groups often died of hemorrhage with a median time of death of 2 to 4 hours.  Remember however that this is a retrospective study with the high, medium and low ratio group created after the fact.

David S. Smith, M.D., Ph.D.

Reversing lung collapse and hypoxemia in early ARDS

Barry Fuchs (Medical Director of MICU, HUP, UPENN) calls our attention to a recent paper on the use of the recruitment maneuver to reverse lung collapse.  The new information in this paper relates to the degree and duration of the recruitment maneuver.  From the abstract: Objectives: To test if a bedside recruitment strategy, capable of reversing hypoxemia and collapse in 95% of lung units, is clinically applicable in early acute respiratory distress syndrome.  Measurements and Main Results: Twenty-six patients received sequential increments in inspiratory airway pressures (5 cm water steps) until the sum of PaO2 + PaCO2 was greater than or equal to 400 mm Hg or preset stopping criteria of mixed venous saturation less than 80%, mean arterial pressure less than 60 mmHg or barotrauma identified by CT was met.  Whenever the primary target was not met, despite inspiratory pressures reaching 60 cm H2O, the maneuver was considered incomplete. Late assessment of recruitment efficacy was performed by computed tomography (9 patients) or by online continuous monitoring in the intensive care unit (15 patients) for up to 6 h. It was possible to open the lung and to keep the lung open in the majority (24/26) of patients, at the expense of transient hemodynamic effects and hypercapnia but without major clinical consequences.  No barotrauma directly associated with the maneuver was detected. There was a strong and inverse relationship between arterial oxygenation and percentage of collapsed lung mass (R 0.91; p < 0.0001).  From Borges JB et al: Am J Respir Critic Care Med 2006;174:268.

David S. Smith, M.D., Ph.D.

Anesthesiologists and nurses apparantly infect patients with hepatitis C because of unsafe practices that have been previously demonstrated to transmit disease

It can be difficult to discern the exact nature of events from the initial news stories however it appears that physicians and nurses in an outpatient endoscopy clinic located in Las Vegas Nevada improperly drew doses of sedatives for patients from a single multi dose vial possibly exposing 40,000 patients to a risk of hepatitis C or aids.  Apparently they did not use a fresh syringe and needle for each entry into the vial so that transmission between patients via the vial contents was possible.  I cannot believe this has happened – it seems so contrary to every teaching on disease transmission and current safe practice.  Do not even consider reusing the same syringes or needles between patients.  Any item that is used on more than one patient should be designed for such use and properly disinfected between uses.

However the above is not a unique event.  On several occasions in the recent past anesthesiologists have been identified with transmitting Hepatitis C through the misguided practice of syringe/needle reuse and multi dose vials.  In 2002 there was a hepatitis C outbreak in Norman Oklahoma related to needle and syringe reuse.  About 71 people were infected there.  In 2007, an anesthesiologist from Dix Hills New York was associated with a cluster of Hepatitis C infections related to his practice.  As a result 11,000 of his former patients were contacted about infection risk.  Also in 2007 another anesthesiologist, was sued for Hepatitis C transmission from faulty infection control practice while giving anesthesia for colonoscopy.  This last anesthesiologist practiced at about 10 different physician offices and about 4,500 of his former patients were placed at risk because of his failure to use reasonable infection control.

The ASA newsletter (66:2002) provides a summary of the ASA infection control guidelines: 1) Syringes and needles are sterile, single-patient-use items. 2) After entry into or connection with a patient’s intravenous infusion, the syringe and needle should be considered contaminated and used only for that patient. 3) Medication from a syringe must not be administered to multiple patients even if the needle on the syringe is changed. 4) All infusion fluids, administration sets (intravenous tubing and connections) and pressure transducer setups are single-patient-use items. Absence of blood contamination cannot be guaranteed by visual inspection. 5) Sterile needles and syringes should always be used to aspirate the contents of an ampule or vial. 6) Each time a multidose vial is entered, aseptic techniques should be used, including cleansing the rubber stopper with alcohol and using a sterile needle and syringe. If visible contamination of a multidose vial has occurred or if sterility is questionable, the vial should be discarded. 7) Immediately after use, or at least at the end of each patient’s anesthetic, all used syringes and needles should be discarded in an appropriate puncture-resistant sharps container. Unused syringes, needles and related items should be stored in a clean area to avoid contamination by contaminated syringes and equipment. 8) Health care workers with breaks in the skin or exudative or weeping lesions should refrain from direct patient contact and from handling patient care equipment unless the open area can be protected. Strict attention to hand washing, hand antisepsis, aseptic technique and use of gloves and other barrier precautions is important to avoid transmission of pathogenic microorganisms to patients and health care workers.

There apparently persists the misguided concept that injecting high on the iv tubing is safe.  This is wrong!  The ASA Newsletter article cited above notes the following: In 1990, Trepanier et al. investigated the risk of cross-infection related to the multiple use of disposable syringes for anesthesia in the operating room. The rate of blood contamination in the intravenous (I.V.) tubing was 3.3 percent at the injection site closest to the I.V. catheter and 0.3 percent at the furthest site. The presence of a one-way check-valve did not affect the contamination rate. Trepanier and his group also found that changing the needle alone on a used syringe was useless for preventing contamination of blood into the syringe.

Considering the difficulty in maintaining sterility and preventing contamination of multi dose containers several states are considering a ban on their use for most medications.  Once a syringe is connected to a patient’s IV it is by definition contaminated and should never be used on another patient.  If a multidose vial has been entered by a syringe and needle that has been in contact with a patient that vial is also contaminated and should be discarded once the care of that patient is over.  It would be prudent not to use multidose vials between patients but to discard the remaining drug at the end of each case.  A Google news search on any of the key words mentioned will bring up the innumerable newspaper sources for this material.

Reference: Trepanier CA et al: Risk of cross-infection related to the multiple use of disposable syringes. Can J Anaesth 1990;37:156-159

David S. Smith, M.D., Ph.D.

MRI related injuries are increasing

The Joint Commission has just issued Sentinel Event Alert #38 on MRI accidents. http://www.jointcommission.org/SentinelEvents/SentinelEventAlert/sea_38.htm
            Based on the FDA’s accident reporting database (believed to represent significantly less than 10% of events), accidents in the MRI suite have experienced a dramatic increase. This increase is believed to reflect a number of combined risk factors including (1) greater attractive forces from newer magnet systems, (2) higher patient acuity levels, (3) increasing interventional applications and (4) growing numbers of sedation / anesthesia patients.
            The current Sentinel Event Alert identifies risks associated with several issues, including heating, implants that are contraindicated in the MR environment, and projectile / missile events.

Heating:
            Heating incidents can arise from improper positioning of the patient during the exam or incorrect settings on the MRI for a particular scan. Corrective actions can include providing insulation between the patient and the MRI, proper body positioning, and review of scan parameters.
Implants:
            A number of implants, both active devices such as pacemakers and passive implants such as aneurysm clips, can present significant dangers to patients when exposed to either static (unchanging) or time-varying magnetic fields. Other implants, such as the leads used in cardiac devices or nerve stimulators, can experience significant local heating as a product of the normal radiofrequency (RF) energies used during the MRI examination process. Corrective actions to prevent scanning of patients with contraindicated implants include a careful review of the patient’s medical record, patient interviews, education of referring physicians, and scrutiny of all identified surgical procedures. (For up-to-date information on the safety of implants, please visit http://www.MRIsafety.com or http://www.doctordoctor.biz )
Projectiles:
            Despite the near-universal awareness of MRI magnets’ extreme power of attraction, objects containing steel are regularly brought into MRI rooms where they are ‘sucked’ into the MRI scanner. Often, these objects are small enough to be removed by hand, but larger objects often require very expensive service calls to have them removed from the scanner. Small objects such as bobby pins and nail clippers, however, can – and do – cause injuries when drawn into MRI magnets, striking patients and/or staff. Corrective actions to prevent projectile accidents include increased vigilance in screening patients and objects, as well as the gowning of all patients. One specific recommendation of the Sentinel Event Alert is for the use of contemporary ferromagnetic detection (FMD) systems specifically designed to find projectile threats in the MRI suite. (For links to all three manufacturers of FMD systems, see http://www.MRI-Planning.com/vendor_links.html ) (from the NPSF patient safety foundation list server).