The Doctor's Channel - Anesthesiology

Transcatheter aortic valve implantation leaves 1 in 10 patients with kidney injury

2010-01-27T22:50:42+00:00

NEW YORK (Reuters Health) - The incidence of acute kidney injury after transcatheter aortic valve implantation (TAVI) is higher than 10%, a Canadian study shows. As reported in an early online issue of the European Heart Journal, these injuries increase the risk of postprocedural death by a factor of 4.

Still, in patients with chronic kidney disease at baseline, acute kidney injury is less common with a transcatheter approach than with open surgery, the authors found.

"Acute kidney injury is one of the most serious complications following cardiac surgery," senior author Dr. Josep Rodes-Cabau, from Laval University, Quebec City, commented to Reuters Health. "In patients with severe aortic stenosis, TAVI has emerged as an alternative to surgery for those patients considered at very high or prohibitive surgical risk, but very few data were available on the occurrence and prognosis of acute kidney injury following TAVI."

The need for contrast media, short periods of extreme hypotension, and manipulation of large catheters in the aorta all add to the risk for kidney injury after TAVI, he and his colleagues point out.

Their analysis included data on 213 patients (mean age 82 years) who underwent TAVI for severe aortic stenosis between 2005 and 2009. One hundred nineteen of these patients had pre-existing chronic kidney disease; this group was compared with a control group of 104 chronic kidney disease patients who had isolated surgical aortic valve replacement.

Acute kidney injury was defined as a drop in estimated glomerular filtration rate (EGFR) of 25% or more in the 48 hours following the procedure, or a need for hemodialysis during that hospitalization.

This endpoint occurred in 25 patients (11.7%), with 1.4% requiring dialysis. Independent predictors of acute kidney injury following TAVI were hypertension, chronic obstructive pulmonary disease, and red blood cell transfusion.

In-hospital mortality was 28% in patients with kidney injury, versus 7.4% among those with no kidney injury (p = 0.005), according to the researchers.

When the two cohorts with baseline chronic kidney disease were compared, the transcatheter group was older, with more comorbidities and a lower mean EGFR, than the surgical group (p < 0.0001 for each).

But despite its higher risk profile, the TAVI group had a lower rate of acute kidney injury than the surgery group (9.2% vs 25.9%, odds ratio 0.29, p = 0.001).

"In patients undergoing TAVI, optimal pre- and post-procedural hydration is very important, and our results suggest that efforts should be made to avoid unnecessary blood transfusions," Dr. Rodes-Cabau commented.

He added, "Continued efforts to minimize the amount of contrast media in these procedures (contrast dilution, contrast hand injections, echocardiography guidance for valve positioning) are also important in further reducing the risk of acute kidney injury following TAVI."

Because acute kidney injury nearly quadrupled the risk of death, the researchers recommend assessment of kidney function within 48 hours.

The authors caution that their results may not apply to lower volume hospitals, "especially at the beginning of the learning curve" for the transcatheter approach. Also, they consider their findings hypothesis generating and in need of confirmation by prospective randomized trials.

Eur Heart J 2009.

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Surgery duration linked to infectious complications, hospital stay

2010-01-12T17:16:46+00:00

NEW YORK (Reuters Health) – New research indicates that operative times are independently and directly linked to the risk of infectious complications and the length of hospital stay.

“These data show that operative duration remains associated with increasing infectious complications in a broad spectrum of general surgery patients after adjustment for numerous patient and operative risks,” Dr. Levi D. Procter and colleagues, from the University of Kentucky College of Medicine, Lexington, note.

In a study of nearly 300,000 operations performed at 173 hospitals from 2005 to 2007, the authors found that the 30-day rate of infectious complications rose by almost 2.5% for every 30 minutes between incision and closing. The rates ranged from 3.7% for cases lasting up to an hour to 31.4% for cases that took more than 6 hours (p < 0.001), according to the report in the January issue of the Journal of the American College of Surgeons.

After adjusting for patient risk variables, type and complexity of surgery, wound class, and intraoperative transfusion, operative time was still a significant predictor of infectious complications. Compared to patients whose operation no more than an hour, those whose surgery lasted 2.1 to 2.5 hours had nearly double the risk of infectious complications, the report indicates.

This pattern was also seen in a subgroup of otherwise healthy patients who had laparoscopic cholecystectomy with a clean or clean-contaminated wound and no blood transfusion. In this subset, infections rates were 0.7% when cases lasted less than 30 minutes, 1.4% in cases lasting from 60 to 90 minutes, and 1.7% in cases longer than 90 minutes.

“Across all procedures,” hospital stays increased geometrically along with operative times, at a rate of about 6% for every 30 minutes, the authors said.

“Our data contribute to our understanding of the independent infection risk relative to operative duration across a broad range of procedures in a very large, multicenter contemporary patient population,” the researchers conclude. “Strategies to reduce operative duration can reduce infectious complications and length of stay.”

Reference:
J Am Coll Surg 2010;210:60-65.

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Chlorhexidine-alcohol tops povidone-iodine for surgical site antisepsis

2010-01-08T16:20:12+00:00

NEW YORK (Reuters Health) – Prepping a patient’s skin with chlorhexidine-alcohol rather than with povidone-iodine reduces both superficial and deep incisional infections after clean-contaminated surgery, according to a report in The New England Journal of Medicine for January 7.

“No published randomized studies have examined the effect of one antiseptic preparation as compared with another on the incidence of surgical-site infection,” Dr. Rabih O. Darouiche, from Baylor College of Medicine, Houston, and colleagues note. Moreover, the Centers for Disease Control and Prevention have not recommended one agent over another for preventing such infections.

In the current study, the authors assessed 30-day surgical-site infection rates in patients who were randomized to receive preoperative skin preparation with chlorhexidine-alcohol scrub or povidone-iodine scrub and paint. The intention-to-treat analysis featured 849 subjects, while the per-protocol analysis included 813 patients who remained in the study throughout the 30-day follow-up period.

On the intention-to-treat analysis, the overall surgical site infection rate was significantly lower in the chlorhexidine-alcohol group than in the povidone-iodine group: 9.5% vs. 16.1% (p = 0.004). Further analysis showed that this held true for superficial (4.2% vs. 8.6%, p = 0.008) and deep (1% vs. 3%, p = 0.05) incisional infections, but not for organ-space infections (4.4% vs. 4.5%). Similar findings were seen in the per-protocol analysis.

The authors estimate that 17 surgical patients would need to receive chlorhexidine-alcohol instead of povidone-iodine to prevent one case of surgical site infection.

In a second study published in the same issue, a separate group of researchers examined the impact of Staphylococcus aureus nasal carriage on the risk of surgical-site infection and then looked at how decolonization of nasal and extranasal sites affected the risk.

Of 6771 patients who were screened with a real-time PCR assay, 1251 tested positive for S. aureus nasal carriage. Of these patients, 808 underwent a surgical procedure and were randomized to receive mupirocin nasal ointment and chlorhexidine soap or placebo ointment and soap starting at hospital admission and continuing for 5 days.

The healthcare-associated S. aureus infection rate was significantly lower in the chlorhexidine-mupirocin group than in controls: 3.4% vs. 7.7% (RR, 0.42). Deep surgical site infections were the most common type and here the difference between the groups was particularly evident: 0.9% vs. 4.4% (RR, 0.21).

“The weight of evidence suggests that chlorhexidine-alcohol should replace povidone-iodine as the standard for preoperative surgical scrubs,” Dr. Richard P. Wenzel, from Commonwealth University, Richmond, comments in a related editorial.

As for intranasal mupirocin and chlorhexidine baths for carriers of S. aureus, he continues, these “could be reserved primarily for patients who are undergoing cardiac surgery, all patients receiving an implant, and all immunosuppressed surgical candidates.”

N Engl J Med 2010;362:9-17,18-26,75-77.

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Elevated INR in liver disease not protective against clots

2010-01-08T16:05:13+00:00

NEW YORK (Reuters Health) - Although patients with liver disease often have an increased international normalized ratio (INR), their coagulopathy does not protect against venous thromboembolism (VTE), new research suggests.

The findings stem from a study of 190 hospitalized patients with chronic liver disease. Twelve patients developed VTE, resulting in a rate of 6.3%. Most importantly, the rate did not vary significantly by INR quartile.

"An elevated INR in the setting of chronic liver disease does not appear to protect against the development of hospital-acquired VTE," conclude Dr. Ousama Dabbagh and colleagues from the University of Missouri, Columbia. "The notion that 'auto-anticoagulation' protects against venous thromboembolism is unfounded."

In the study, which was reported in the December 29th online issue of Chest, patients were divided into quartiles based on admission INR cutoffs of 1.4, 1.7, and 2.2. In all four groups, the most common cause of liver disease was alcohol, followed by hepatitis B or C. Roughly 25% of patients received either mechanical or drug prophylaxis of thrombosis; the rate was comparable in each INR group.

Not surprisingly, in the overall cohort, patients with higher INRs were generally sicker. Of the 12 patients with VTE, 1 was Child-Pugh stage A, 3 were B, and 8 were C.

While hospital length of stay was similar among INR groups, hospital mortality rates rose with higher INRs (32% in highest INR group vs. 4% in lowest INR group, p < 0.001).

"In this study, half of cases of VTE occurred in patients with INR greater than 1.6, and there was still a risk of VTE with INR greater than 2.2," the authors warn.

They conclude, "Our study shows that elevated INR in chronic liver disease should not give clinicians a sense of security."

Reference:
Chest 2009.

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Outpatient ketamine improves post-trauma pain syndrome

2009-12-30T17:31:26+00:00

NEW YORK (Reuters Health) - Outpatient infusions of ketamine can significantly improve the severe pain of complex regional pain syndrome, a chronic problem after trauma, a small study has found.

The exact pathophysiology of complex regional pain syndrome is unknown, but N-methyl-D-aspartate (NMDA) receptors are thought to play a key role, according to the researchers. Ketamine, which is a potent NMDA antagonist, has already been reported to relieve the condition, but earlier studies have involved several consecutive days of anesthetic doses, or continuous or nearly continuous sub-anesthetic doses.

In their pilot study, Dr. Robert J. Schwartzman and colleagues from Drexel University College of Medicine, Philadelphia, wanted to find a ketamine regimen that could potentially achieve the complete, long-lasting remissions seen with multiple days of anesthetic doses, but with sub-anesthetic doses in outpatients.

In the December 15th issue of Pain, the investigators report on 19 patients with severe, long-standing complex regional pain syndrome who were randomized to receive 4-hour infusions of ketamine (25 mL/h) or placebo each day for 10 days, with a limit of 25 mg/h over 4 hours. All subjects also received clonidine and midazolam.

The original plans called for 40 subjects. In fact, the trial was stopped after 19 patients had been accrued, because there was almost no placebo effect, whereas the 9 patients in the ketamine group had benefits immediately.

Ketamine produced significant improvements on scores for a 7-question pain questionnaire and on the short form McGill pain questionnaire. Data from activity sensors worn by each subject also suggested improvements in pain. No significant improvements in quantitative sensory testing or quality of life were noted, however.

Four of 9 patients in the ketamine group and 2 of 10 in the placebo group complained of nausea, headache, tiredness, or dysphoria at some point during the trial, but there were no serious adverse effects.

"The results of this study warrant a larger randomized placebo-controlled trial using higher doses of ketamine and a longer follow-up period," the authors conclude.

Reference:
Pain 2009;147:107-115.

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Many endoscopy patients at high risk for obstructive sleep apnea

2009-12-21T15:22:02+00:00

NEW YORK (Reuters Health) – More than a third of patients undergoing routine outpatient endoscopic procedures are at high risk for obstructive sleep apnea (OSA), according to findings from a prospective study at a university hospital.

The good news is that high-risk patients are not more likely to experience transient hypoxia during sedation for endoscopic procedures.

OSA is under-recognized, and it is unclear how many endoscopy patients may have undiagnosed OSA. OSA patients are known to be at higher risk for anesthesia-related cardiopulmonary complications during deep sedation. Their risk of complications during conscious sedation is not known, however.

To address this question, Dr. Vijay S. Khiani, from Yale University, New Haven, Connecticut, and associates administered the validated Berlin OSA questionnaire to 233 patients before routine esophagogastroduodenoscopy or colonoscopy. Based on their responses, patients categorized either as low or high risk for OSA.

During endoscopy, the subjects were assessed for transient hypoxia, defined as a pulse oximetric reading below 92% that required an increase in supplemental oxygen.

Overall, 90 patients (39%) were at high risk for OSA. The rate of transient hypoxia in this group, 10%, was not significantly different from the 7% rate in the low risk group.

The results suggest that “the majority of patients at risk of OSA can safely undergo conscious sedation for routine endoscopic procedures by using standard sedation and monitoring practices,” the authors conclude.

Reference:
Gastrointest Endosc 2009;70:1116-1120.

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Methadone a good option for cancer pain in outpatients

2009-12-10T11:04:02+00:00

NEW YORK (Reuters Health) – Methadone is a safe, effective first- or second-line treatment of cancer pain, even in outpatients, a retrospective study suggests.

Concerns over its long half-life, its variable relative potency, and potential cardiotoxicity have led to the common opinion that methadone is difficult to manage in the outpatient setting.

To the contrary, Dr. Eduardo Bruera and associates at the University of Texas M. D. Anderson Cancer Center in Houston found in their chart review that methadone “is an ideal drug for opioid rotation because of its efficacy, higher oral bioavailability, lack of known active metabolites, incomplete cross tolerance with other mu receptor agonists, and lower cost.”

Dr. Bruera and his team studied 89 consecutive “strong opioid-naïve” cancer patients treated with methadone and 100 who were switched to it from another opioid, all between 2003 and 2007. Their findings are published online in the journal Cancer.

The median times from baseline to the first and second follow-ups were 13 and 37 days, respectively. Factors that defined success were an improvement in pain of at least 30% or at least 2 points in the Edmonton Symptom Assessment Scale pain score and/or disappearance of side effects at the first follow-up visit, and – in patients originally given a different opioid – resolution of the problem with the previous drug.

Success rates were 92% in the first-line group, 85% in patients switched from other drugs, and 88% overall. Median pain scores at baseline and the first and second follow-ups were 6, 4, and 3, respectively.

Pain scores improved in all groups, and nausea and constipation were reduced in both groups. Side effects were “tolerable,” and there was no increase in sedation, hallucinations, myoclonus or delirium.

At the first follow-up visit, median methadone doses were 10 mg/day for first-line patients and 15 mg/day for patients who switched from another drug. Corresponding values at the second follow-up visit were 10 and 18 mg/day.

The authors report that patients who switched to methadone had been taking a median morphine equivalent daily dose (MEDD) of 100 mg/day (range, 60 to 185). On both univariate and multivariate analyses, the MEDD of the previous drug was significantly associated with the MEDD:methadone ratio. Furthermore, in the multivariate models, the reason for rotation and previous opioid doses were independently associated with higher MEDD:methadone ratios.

These findings, the authors warn, suggest that with regard to opioid sensitivity, “methadone behaves in a different manner as compared with other opioids,” and patients who had escalation of their previous opioids require particularly cautious treatment.

In addition, they advise, because methadone is metabolized via cytochrome 3A4, patients taking 3A4 inhibitors (e.g., fluconazole, ciprofloxacin, venlafaxine, fluoxetine, and macrolides) are at risk for elevated, possibly toxic methadone levels. Similar effects are possible from inhibitors of cytochrome 2B6 (e.g., haloperidol, levopromazine, paroxetine, sertraline, fluoxetine, and chlorimipramine) and inhibitors of P-glycoprotein (doxorubicin, vimblastin, and actinomycin).

And because of potential cardiac effects, clinicians must check for electrolyte imbalances or concomitant use of other cardiotoxic drugs, such as tricyclic antidepressants, diuretics, and antipsychotics.

Summing up, the authors write, “Our study adds to the growing evidence in the literature” to recommend the use of methadone in these circumstances.

Furthermore, they point out, methadone is much less expensive – and therefore more affordable for patients – compared to other pain-controlling medications.

Reference:
Cancer 2009.

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Subcutaneous infusion in children

2009-12-07T16:58:16+00:00

Sharon Mace, MD, Pediatrician and Emergency Medicine Physician in Emergency Department, Cleveland Clinic, discusses subcutaneous fluid administration in children who are not amenable to IV insertion, and talks about the PEDS 2 trial which shows that subcutaneous fluid administration is faster, more effective and gives greater parent and doctor satisfaction than IV fluid use.

Reading:
Allen CH, Etzwiler LS, Miller MK, Maher G, Mace S, Hostetler MA, Smith SR, Reinhardt N, Hahn B, Harb G; for the INcreased Flow Utilizing Subcutaneously- Enabled-(INFUSE) Pediatric Rehydration Study Collaborative Research GroupRecombinant Human Hyaluronidase-Enabled Subcutaneous Pediatric Rehydration. Allen CH, Etzwiler LS, Miller MK, Maher G, Mace S, Hostetler MA, Smith SR, Reinhardt N, Hahn B, Harb G; for the INcreased Flow Utilizing Subcutaneously- Enabled-(INFUSE) Pediatric Rehydration Study Collaborative Research Group. Pediatrics. 2009 Oct 5.
Migowa AN, Gatinu B, Nduati RW. Adherence to Oral Rehydration Therapy among In-Patient Children Aged 1-59 Months with Some or No Dehydration. J Trop Pediatr. 2009 Jul 14.
Parkin PC, Macarthur C, Khambalia A, Goldman RD, Friedman JN. Clinical and Laboratory Assessment of Dehydration Severity in Children With Acute Gastroenteritis. Clin Pediatr (Phila). 2009 Jun 1.

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VIP network for hospitalists

2009-12-07T15:35:17+00:00

Matt Garber MD, Assistant Professor of Pediatrics and Director of Pediatric Hospitalists at the University of Southern California, discusses the VIP or Value in Inpatient Pediatrics Network, a grassroots effort by 5 pediatric hospitalists to collect and analyze data from hospitals across the US, and benchmark hospitals that do well with processes and outcomes.

Reading:
Beck CE, Parkin PC, Friedman JN. Pediatric hospitalist medicine: an overview and a perspective from Toronto, Canada. Clin Pediatr (Phila). 2008 Jul;47(6):546-8.
Teufel RJ 2nd, Garber M, Taylor RC. Pediatric hospitalist: a national and regional trend. J S C Med Assoc. 2007 Jun;103(5):126-9.
Gilca R, De Serres G, Skowronski D, Boivin G, Buckeridge DL. The need for validation of statistical methods for estimating respiratory virus-attributable hospitalization.

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Best peer reviewed article for pediatric hospitalists

2009-12-07T15:32:47+00:00

Matthew Garber, MD, Assistant Professor of Pediatrics and Director of Pediatric Hospitalists at the University of South Carolina, discusses one of his top ten pediatric hospitalist journal articles by author R.P. Bekmezian, which examined generalist outcomes in pediatric patients treated by generalist pediatric hospitalists versus those who had been treated by various subspecialty teams.

Reading:
Bekmezian A, Chung PJ, Yazdani S. Staff-only pediatric hospitalist care of patients with medically complex subspecialty conditions in a major teaching hospital. Arch Pediatr Adolesc Med. 2008 Oct;162(10):975-80.
Chamberlain JK, Cull WL, Melgar T, Kaelber DC, Kan BD. The effect of dual training in internal medicine and pediatrics on the career path and job search experience of pediatric graduates. J Pediatr. 2007 Oct;151(4):419-24. Epub 2007 Aug 23.
Percelay JM; Committee on Hospital Care. Physicians' roles in coordinating care of hospitalized children. Pediatrics. 2003 Mar;111(3):707-9.

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