Archive for the ‘Articles’ Category

Pt s/p CVA. How long to wait before elective surgery?

Tuesday, July 29th, 2014

The literature has numerous studies examining the effect of timing of surgery after MI and coronary stenting and MACE (major adverse cardiovascular events).  However, for stroke, data is sparse.

Now comes a study from Denmark, published in JAMA.  In Denmark, all medical data is collected (single payer), allowing retrospective databases studies to be done on complete, reliable datasets.  The disadvantage is that it is an ethnically uniform database, which the authors correctly say potentially limits the generalizability of the results.  They looked at “Danish nationwide cohort study (2005-2011) including all patients aged 20 years or older undergoing elective noncardiac surgeries (n=481 183 surgeries)”; 7137 had had prior stroke.

What I found fascinating is that a key part of their data was a nationwide Anesthesia database:

Information on several surgery-related variables, including whether the surgery was acute or elective, was retrieved from the Danish Anesthesia Register, in which all surgeries requiring anesthesia have been registered since mid-2004.

So, what did they find?

In summary, we demonstrated that prior ischemic stroke, irrespective of time between ischemic stroke and surgery, was associated with an adjusted 1.8- and 4.8-fold increased relative risk of 30-day mortality and 30-day MACE, respectively, compared with patients without prior stroke. Second, we demonstrated a strong time-dependent relationship between prior stroke and adverse postoperative outcome, with patients experiencing a stroke less than 3 months prior to surgery at particularly high risk. The risk stabilized after approximately 9 months. Third, the increased relative risks associated with prior stroke were found to be of at least similar magnitudes in low- and intermediate-risk surgeries, as in high-risk surgeries.

Red arrows show the particularly high odds ratios of MACE, death, and new stroke when surgery is performed < 3 months after prior CVA.
Red arrows show the particularly high odds ratios of MACE, death, and new stroke when surgery is performed < 3 months after prior CVA.

Elective surgery in the first 3 months is associated with much higher MACE rates.  These rates stabilize by 9 months s/p CVA.

The authors did multiple analyses to try to limit the confounding effect that early surgery after stroke might indicate a not-elective indication for surgery.  For example, they looked at the association of time after stroke and total knee or hip replacement (without fracture – presumably elective), and found similar elevated rates of MACE in the first 3 months.

There is possible room for improvement, since only 52% of prior CVA patients were chronically on statins, and only 65% on antiplatelet meds (such as aspirin and/or plavix) before surgery.  Indeed, when adjusted for comorbidities, they found that in patients with prior CVA, chronic statins and antiplatelets meds were associated with reductions in postop MACE, including death from any cause.

What are some take away points?

  • Elective surgery should probably wait until 9 months after surgery.
  • This is probably true for low risk and intermediate risk surgeries, not just major ones.
  • These results likely do not apply to CEA or carotid stenting, where the goal is to repair the source of arterial occlusion and/or thromboembolism


Recent evidence and guidelines of periop management of obstructive sleep apnea (OSA).

Wednesday, June 26th, 2013

Recent evidence and guidelines of periop management of obstructive sleep apnea (OSA).


Articles discussed:

1. Chest. 2013 May;143(5):1284-93. doi: 10.1378/chest.12-1132.

Serum bicarbonate level improves specificity of STOP-bang screening for
obstructive sleep apnea.

Chung F, Chau E, Yang Y, Liao P, Hall R, Mokhlesi B.

Department of Anesthesia, Toronto Western Hospital, University Health Network,
University of Toronto, Toronto, ON, Canada.

BACKGROUND: The STOP-Bang questionnaire is a validated screening tool for the
identification of surgical patients with obstructive sleep apnea (OSA). A
STOP-Bang score ≥ 3 is highly sensitive but only moderately specific.
Apnea/hypopnea during sleep can lead to intermittent hypercapnia and may result
in serum bicarbonate (HCO₃⁻) retention. The addition of serum HCO₃⁻ level to the 
STOP-Bang questionnaire may improve its specificity.
METHODS: Four thousand seventy-seven preoperative patients were approached for
consent and screened by the STOP-Bang questionnaire. Polysomnography was
performed and preoperative HCO₃⁻ level was collected in 384 patients. Study
participants were randomly assigned to a derivation or validation cohort.
Predictive parameters (sensitivity, specificity, positive and negative predictive
values) for STOP-Bang score and serum HCO₃⁻ level were calculated.
RESULTS: In the derivation cohort, with a STOP-Bang score ≥ 3, the specificity
for all OSA, moderate/severe OSA, and severe OSA was 37.0%, 30.4%, and 27.7%,
respectively. HCO₃⁻ level of 28 mmol/L was selected as a cutoff for analysis.
With the addition of HCO₃⁻ level ≥ 28 mmol/L to the STOP-Bang score ≥ 3, the
specificity for all OSA, moderate/severe OSA, and severe OSA improved to 85.2%,
81.7%, and 79.7%, respectively. Similar improvement was observed in the
validation cohort.
CONCLUSION: Serum HCO₃⁻ level increases the specificity of STOP-Bang screening in
predicting moderate/severe OSA. We propose a two-step screening process. The
first step uses a STOP-Bang score to screen patients, and the second step uses
serum HCO₃⁻ level in those with a STOP-Bang score ≥ 3 for increased specificity.

PMID: 23238577  [PubMed - in process]

2. Anesth Analg. 2012 Nov;115(5):1060-8. doi: 10.1213/ANE.0b013e318269cfd7. Epub
2012 Aug 10.

Society for Ambulatory Anesthesia consensus statement on preoperative selection
of adult patients with obstructive sleep apnea scheduled for ambulatory surgery.

Joshi GP, Ankichetty SP, Gan TJ, Chung F.

Department of Anesthesiology and Pain Management, University of Texas
Southwestern Medical Center, Dallas, TX 75390-9068, USA.

The suitability of ambulatory surgery for a patient with obstructive sleep apnea 
(OSA) remains controversial because of concerns of increased perioperative
complications including postdischarge death. Therefore, a Society for Ambulatory 
Anesthesia task force on practice guidelines developed a consensus statement for 
the selection of patients with OSA scheduled for ambulatory surgery. A systematic
review of the literature was conducted according to the Preferred Reporting Items
for Systematic Reviews and Meta-Analyses guidelines. Although the studies
evaluating perioperative outcome in OSA patients undergoing ambulatory surgery
are sparse and of limited quality, they do provide useful information that can
guide clinical practice. Patients with a known diagnosis of OSA and optimized
comorbid medical conditions can be considered for ambulatory surgery, if they are
able to use a continuous positive airway pressure device in the postoperative
period. Patients with a presumed diagnosis of OSA, based on screening tools such 
as the STOP-Bang questionnaire, and with optimized comorbid conditions, can be
considered for ambulatory surgery, if postoperative pain can be managed
predominantly with nonopioid analgesic techniques. On the other hand, OSA
patients with nonoptimized comorbid medical conditions may not be good candidates
for ambulatory surgery. What other guidelines are available on this topic? The
American Society of Anesthesiologists (ASA) practice guidelines for management of
surgical patients with OSA published in 2006. Why was this guideline developed?
The ASA guidelines are outdated because several recent studies provide new
information such as validated screening tools for clinical diagnosis of OSA and
safety of ambulatory laparoscopic bariatric surgery in OSA patients. Therefore,
an update on the selection of patients with OSA undergoing ambulatory surgery is 
warranted. How does this guideline differ from existing guidelines? Unlike the
ASA guidelines, this consensus statement recommends the use of the STOP-Bang
criteria for preoperative OSA screening and considers patients' comorbid
conditions in the patient selection process. Also, current literature does not
support the ASA recommendations that upper abdominal procedures are not
appropriate for ambulatory surgery. Why does this guideline differ from existing 
guidelines? This consensus statement differs from existing ASA guidelines because
of the availability of new evidence.

PMID: 22886843  [PubMed - indexed for MEDLINE]

3. N Engl J Med. 2013 Jun 20;368(25):2352-3. doi: 10.1056/NEJMp1302941.

A rude awakening--the perioperative sleep apnea epidemic.

Memtsoudis SG, Besculides MC, Mazumdar M.

Department of Anesthesiology, Hospital for Special Surgery, Weill Medical College
of Cornell University, New York, USA.

PMID: 23782177  [PubMed - in process]

4. Reg Anesth Pain Med. 2013 Jul-Aug;38(4):274-81. doi:

Sleep Apnea and Total Joint Arthroplasty under Various Types of Anesthesia: A
Population-Based Study of Perioperative Outcomes.

Memtsoudis SG, Stundner O, Rasul R, Sun X, Chiu YL, Fleischut P, Danninger T,
Mazumdar M.

From the *Department of Anesthesiology, Hospital for Special Surgery, †Division
of Biostatistics and Epidemiology, Department of Public Health; and ‡Department
of Anesthesiology, New York-Presbyterian Hospital, Weill Medical College of
Cornell University, New York, NY.

BACKGROUND AND OBJECTIVES: The presence of sleep apnea (SA) among surgical
patients has been associated with significantly increased risk of perioperative
complications. Although regional anesthesia has been suggested as a means to
reduce complication rates among SA patients undergoing surgery, no data are
available to support this association. We studied the association of the type of 
anesthesia and perioperative outcomes in patients with SA undergoing joint
METHODS: Drawing on a large administrative database (Premier Inc), we analyzed
data from approximately 400 hospitals in the United States. Patients with a
diagnosis of SA who underwent primary hip or knee arthroplasty between 2006 and
2010 were identified. Perioperative outcomes were compared between patients
receiving general, neuraxial, or combined neuraxial-general anesthesia.
RESULTS: We identified 40,316 entries for unique patients with a diagnosis for SA
undergoing primary hip or knee arthroplasty. Of those, 30,024 (74%) had
anesthesia-type information available. Approximately 11% of cases were performed 
under neuraxial, 15% under combined neuraxial and general, and 74% under general 
anesthesia. Patients undergoing their procedure under neuraxial anesthesia had
significantly lower rates of major complications than did patients who received
combined neuraxial and general or general anesthesia (16.0%, 17.2%, and 18.1%,
respectively; P = 0.0177). Adjusted risk of major complications for those
undergoing surgery under neuraxial or combined neuraxial-general anesthesia
compared with general anesthesia was also lower (odds ratio, 0.83 [95% confidence
interval, 0.74-0.93; P = 0.001] vs odds ratio, 0.90 [95% confidence interval,
0.82-0.99; P = 0.03]).
CONCLUSIONS: Barring contraindications, neuraxial anesthesia may convey benefits 
in the perioperative outcome of SA patients undergoing joint arthroplasty.
Further research is needed to enhance an understanding of the mechanisms by which
neuraxial anesthesia may exert comparatively beneficial effects.

PMID: 23558371  [PubMed - in process]

5. Anesthesiology. 2012 Jul;117(1):188-205. doi: 10.1097/ALN.0b013e31825add60.

Obesity hypoventilation syndrome: a review of epidemiology, pathophysiology, and 
perioperative considerations.

Chau EH, Lam D, Wong J, Mokhlesi B, Chung F.

Department of Anesthesiology, Toronto Western Hospital, University Health
Network, University of Toronto, Toronto, Ontario, Canada.

Obesity hypoventilation syndrome (OHS) is defined by the triad of obesity,
daytime hypoventilation, and sleep-disordered breathing without an alternative
neuromuscular, mechanical, or metabolic cause of hypoventilation. It is a disease
entity distinct from simple obesity and obstructive sleep apnea. OHS is often
undiagnosed but its prevalence is estimated to be 10-20% in obese patients with
obstructive sleep apnea and 0.15-0.3% in the general adult population. Compared
with eucapnic obese patients, those with OHS present with severe upper airway
obstruction, restrictive chest physiology, blunted central respiratory drive,
pulmonary hypertension, and increased mortality. The mainstay of therapy is
noninvasive positive airway pressure. Currently, information regarding OHS is
extremely limited in the anesthesiology literature. This review will examine the 
epidemiology, pathophysiology, clinical characteristics, screening, and treatment
of OHS. Perioperative management of OHS will be discussed last.

PMID: 22614131  [PubMed - in process]


Beta blockers protective in non-vascular noncardiac surgery, but not in vascular surgery???

Friday, April 26th, 2013

Dr London and colleagues from San Francisco VA have just published a study in JAMA (retrospective; propensity analysis) showing that beta blockers are NOT protective in vascular surgery.  However, they are in non-vascular noncardiac surgery.  The protection increases as the RCRI increases.

Hypotheses as to why no protection in vascular surgery patients:

  • More careful periop care in vascular surgery patients?
  • I think it’s because vascular surgery patients bleed more than others.  In Kamel et al (see below), vascular cases were only 12.5% of cases analysed, but 41% of hemorrhage cases, where definition of major hemorrhage was “requiring transfusion of >4 U of packed red blood cells (PRBCs) or whole blood based on the NSQIP definition”). “Bleeding is Rarely Good for You!” below is the accompanying editorial.

I asked Dr. London if they had analysed bleeding and transfusion in this cohort.  They’d like to do so, but await funding to be able to examine.

Circulation. 2012 Jul 10;126(2):169-71. doi: 10.1161/CIRCULATIONAHA.112.115196.

Circulation. 2012 Jul 10;126(2):169-71. doi: 10.1161/CIRCULATIONAHA.112.115196.

Circulation. 2012 Jul 10;126(2):207-12. doi: 10.1161/CIRCULATIONAHA.112.094326. Epub 2012 Jun 7. Association between major perioperative hemorrhage and stroke or Q-wave myocardial infarction. Kamel H, Johnston SC, Kirkham JC, Turner CG, Kizer JR, Devereux RB, Iadecola C. Source Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY 10065, USA.

Circulation. 2012 Jul 10;126(2):207-12. doi: 10.1161/CIRCULATIONAHA.112.094326. Epub 2012 Jun 7.
Association between major perioperative hemorrhage and stroke or Q-wave myocardial infarction.
Kamel H, Johnston SC, Kirkham JC, Turner CG, Kizer JR, Devereux RB, Iadecola C.
Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY 10065, USA.

Association of Perioperative β-Blockade With Mortality and Cardiovascular Morbidity Following Major Noncardiac Surgery Martin J. London, MD; Kwan Hur, PhD; Gregory G. Schwartz, MD, PhD; William G. Henderson, PhD, MPH JAMA. 2013;309(16):1704-1713. doi:10.1001/jama.2013.4135.

Association of Perioperative β-Blockade With Mortality and Cardiovascular Morbidity Following Major Noncardiac Surgery
Martin J. London, MD; Kwan Hur, PhD; Gregory G. Schwartz, MD, PhD; William G. Henderson, PhD, MPH
JAMA. 2013;309(16):1704-1713. doi:10.1001/jama.2013.4135.


Another nail in the coffin for beta blockers? In this case, BB don’t help chronic AF/CHF patients as much.

Tuesday, February 5th, 2013

From Physicians First Watch:

Beta-Blockers Less Effective in Heart Failure with Atrial Fibrillation

By Joe Elia

Patients with heart failure and atrial fibrillation do not benefit as much from beta-blocker therapy as those with sinus rhythm, according to a meta-analysis in the Journal of the American College of Cardiology: Heart Failure.

Researchers analyzed mortality outcomes from four studies including over 8500 patients with heart failure and reduced left-ventricular ejection fraction (<40%). Roughly 20% also had atrial fibrillation. Although those with atrial fibrillation who received beta-blockers had lower mortality risks than those receiving placebo (odds ratio, 0.86), patients with sinus rhythm fared much better (OR, 0.63). In addition, beta-blockers did not reduce hospitalizations for heart failure among patients with atrial fibrillation, whereas they did among those with sinus rhythm.

Editorialists call the study, “hypothesis-generating,” and conclude that the results “at a minimum” suggest that treatment for those with heart failure and atrial fibrillation “should be approached differently” from those with sinus rhythm.

JACC: Heart Failure article (Free)

JACC: Heart Failure editorial (Free)

Continue, stop, or start ACE inhibitors before cardiac surgery?

Tuesday, July 17th, 2012

Keep your neo/vasopressin handy and deal with it!

A new retrospective study of 4000+ cardiac surgery patients shows that the periop use of ACE-I is associated with reduced morbid events; the primary outcome of the study was defined as the composite outcome of the cardiac, cerebral, and renal events and in-hospital mortality:

“CONCLUSIONS: Our study suggests that withdrawal of ACEI treatment after CABG surgery is associated with non-fatal in-hospital ischemic events. Further, continuation of ACEI or de novo ACEI therapy early after cardiac surgery is associated with improved in-hospital outcomes.”

So, keep your neo/vasopressin handy and deal with it!

Figure 2.

Kaplan–Meier survival analysis of event-free status by angiotensin-converting enzyme inhibitor (ACEI) therapy. The curves show data of 30-day in-hospital composite event-free status. The P value shown is for the comparison of Kaplan–Meier survival function among the 4 groups. The P value was calculated from the log-rank

Screening (and Some Rescreening) for Aortic Aneurysms Found Cost Effective

Friday, July 6th, 2012
BMJ 2012; 345 doi: 10.1136/bmj.e4276 (Published 5 July 2012)

Cite this as: BMJ 2012;345:e4276

Objective To assess the cost effectiveness of different screening strategies for abdominal aortic aneurysm in men, from the perspective of a national health service.

Setting Screening units at regional hospitals.

Participants Hypothetical cohort of 65 year old men from the general population.

Main outcome measures Costs (£ in 2010) and effect on health outcomes (quality adjusted life years (QALYs)).

Results Screening seems to be highly cost effective compared with not screening. The model estimated a 92% probability that some form of screening would be cost effective at a threshold of £20 000 (€24 790; $31 460).

Ultrasound for central lines???

Wednesday, February 29th, 2012

In January 2012 issue of Anesthesia and Analgesia:

Christopher A. Troianos, Gregg S. Hartman, Kathryn E. Glas, Nikolaos J. Skubas, Robert T. Eberhardt, Jennifer D. Walker, Scott T. Reeves,  Guidelines for Performing Ultrasound Guided Vascular Cannulation: Recommendations of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists Anesth Analg January 2012 114:46-72

Our perioperative beta blockade review. Published Dec 2011, before Poldermans misconduct allegations

Friday, January 6th, 2012

“Preoperative anaemia and postoperative outcomes in non-cardiac surgery: a retrospective cohort study”

Thursday, October 6th, 2011

Preoperative anaemia and postoperative outcomes in non-cardiac surgery- a retrospective cohort study Published online October 6, 2011 DOI:10.1016/S0140-6736(11)61381-0

“Methods We analysed data for patients undergoing major non-cardiac surgery in 2008 from The American College of Surgeons’ National Surgical Quality Improvement Program database (a prospective validated outcomes registry from 211 hospitals worldwide in 2008). We obtained anonymised data for 30-day mortality and morbidity (cardiac, respiratory, CNS, urinary tract, wound, sepsis, and venous thromboembolism outcomes), demographics, and preoperative and perioperative risk factors. We used multivariate logistic regression to assess the adjusted and modified (nine predefined risk factor subgroups) eff ect of anaemia, which was defi ned as mild (haematocrit concentration >29–<39% in men and >29–<36% in women) or moderate-to-severe (≤29% in men and women) on postoperative outcomes.

Interpretation Preoperative anaemia, even to a mild degree, is independently associated with an increased risk of 30-day morbidity and mortality in patients undergoing major non-cardiac surgery.”

Vascular patients were more anemic than others (no surprise there).  Any anemia in vascular surgery patients had OR for mortality = 1·44 (1·24–1·68) for morbidity 1·24 (1·14–1·35).

In all patient groups (by level of anemia or not), transfused patients did NOT have increase mortality or morbidity. Go figure.

Does aggressive medical therapy trump cerebral revascularization?

Thursday, September 8th, 2011

NEJM has just published an RCT of INTRAcranial stenting for symptomatic intracranial arterial stenosis vs. aggressive medical therapy.  It showed WORSE outcomes for stenting.

For me, this begs the question of whether NASCET (symptomatic; published 1998) and ACAS (asymptomatic; published 1995) CEA trials need to be repeated, up against aggressive medical Rx.

How was aggressive medical Rx defined in the trial?

Aggressive Medical Management

The rationale for the medical-management regimen and details on the management of risk factors in the study patients have been published previously.21-23…  we targeted a systolic blood pressure of less than 140 mm Hg (<130 mm Hg in the case of patients with diabetes) and an LDL cholesterol level of less than 70 mg per deciliter (1.81 mmol per liter). We provide the aspirin, clopidogrel, one drug from each major class of antihypertensive agents, rosuvastatin, and the lifestyle program to the study patients.

Medical therapy was probably less aggressive in the NASCET study: