icuroom.net October 2009 archive

2009-10-31T17:55:00.001-07:00

Saturday October 31, 2009

Your Diagnosis?

Answer: Atrial fibrillation and complete heart block

Fibrillary waves of atrial fibrillation and no P waves
Regular ventricular rhythm
The wider the QRS of the ventricular escape rhythm the less reliable the escape mechanism
AF with complete heart block can be easily missed and is an indication for a permanent pacemaker

2009-10-30T18:57:00.000-07:00

Friday October 30, 2009
Reglan

Q: Reglan (Metoclopramide) is a very commonly use drug in ICU. Does it get removed via CVVHD ?

A: NO !

(Reglan) Metoclopramide is excreted principally through the kidneys. In patients with creatinine clearance below 40 mL/min, dose should be curtailed at approximately one-half the recommended dosage. Dialysis removes relatively little Metoclopramide. Similarly, continuous ambulatory peritoneal dialysis does not remove significant amounts of drug.

Cumulative doses with prolong ang higher dose may manifest as tardive dyskinesia, a syndrome consisting of potentially irreversible, involuntary, dyskinetic movements. Elderly patients are likely to develop the syndrome. Anticholinergic or antiparkinson drugs or antihistamines with anticholinergic properties may be helpful in controlling the extrapyramidal reactions. Symptoms are self-limiting and usually disappear within 24 hours.

recommended article

1. Drug Dosing in Critically Ill Patients with Renal Failure: A Pharmacokinetic Approach - Journal of Intensive Care Medicine, Volume 15 Issue 6 Page 273-313, November/December 2000

2009-10-29T17:36:00.000-07:00

Thursday October 29, 2009

Q: What could be the supporting finding on lab in (Transfusion-related acute lung injury (TRALI)?

Answer: Laboratory findings may include unexpected haemoconcentration and a sudden fall in serum albumin. As in other causes of acute alveolar capillary leak, the pulmonary exudate in TRALI has a high albumin content. Peripheral blood neutropenia has been reported but neutrophilia is more common.

Reference:

The pathology of transfusion-related acute lung injury. Am J Clin Pathol 1999; 112: 216–21

2009-10-28T19:18:00.000-07:00

Wednesday October 28, 2009
Reference Standard Change for Heparin

Source: www.fda.gov/Safety/medwatch

Effective October 1, 2009, there is a new reference standard and test method to determine the potency of heparin, as well as, impurities in heparin. This change will result in a 10% reduction in potency of heparin marketed in the United States.

Clinicians should take caution with monitoring and dosing, as more heparin may be needed to achieve and maintain desired level of anticoagulation in patients.

Product with the new “USP unit” potency definition will be available on or after October 8, 2009. Most manufacturers will place an “N” next to the lot number to indicate that the vial is of the new potency.

2009-10-27T19:06:00.000-07:00

Tuesday October 27, 2009
Sulfonylurea overdose

Anti-diabetic pills overdose remained one of the leading cause of drug overdose worldwide. Among anti-diabetic pills sulfonylureas are the most dangerous and hard to correct. Overdose of metformin rarely causes clinically evident hypoglycemia (It has its own danger of cardiovascular collapse and renal failure, due to severe lactic acidosis).

Unfortunately very few clinicians use the real antidote for sulfonylurea which is Octreotide (Sandostatin) in resistant hypoglycemia. Infusion of glucose to achieve euglycemia in the early phase is an appropriate treatment but there is some literature available which argues that prolong infusion of dextrose in sulfonylurea overdose may make hypoglycemia longer and worse by stimulating insulin release. The dose for Octreotide is 50 mcg SC every 8 hours with adjustment of dose according to blood glucose level. Octreotide is a somatostatin analogue, which activates G-protein K channel and hyperpolarization of the beta cell results in inhibition of Ca influx and insulin release. Another antidote for sulfonylurea overdose beside octreotide is Diazoxide.

Exact mechanism is unknow but probably it increases blood glucose by inhibiting pancreatic insulin release. It is found to be effective within 60 minutes of administration. The usual dose is 5 mg/kg/day intravenously and should be divided every 8 hours. Dose can be increased if needed but still its experience in comparison to octreotide is limited.

References: click to get abstracts/articles

1. Octreotide for sulfonylurea-induced hypoglycemia following overdose - The Annals of Pharmacotherapy: Vol. 36, No. 11, pp. 1727-1732

2. Clinical spectrum of sulfonylurea overdose and experience with diazoxide therapy - Archives of Internal Medicine Vol. 151 No. 9, September 1, 1991

2009-10-26T19:27:00.000-07:00

Monday October 26, 2009
Going back to basics

Q: Explain Ejection fraction (Ef)?

Answer: By definition, the volume of blood within a ventricle immediately before a contraction is known as the end-diastolic volume. Similarly, the volume of blood left in a ventricle at the end of contraction is end-systolic volume. The difference between end-diastolic and end-systolic volumes is the stroke volume, the volume of blood ejected with each beat. Ejection fraction (Ef) is the fraction of the end-diastolic volume that is ejected with each beat; that is, it is stroke volume (SV) divided by end-diastolic volume (EDV):

Ef = SV/EDV
OR
Ef = EDV-ESV/EDV

In a healthy 70-kg (154-lb) man, the SV is approximately 70 ml (left ventricular ESV is 50 ml and the left ventricular EDV is 120 ml) giving an ejection fraction of 70/120, or 0.58 (58%)

2009-10-25T06:30:00.000-07:00

Sunday October 25, 2009

Q: What is the basis of treatment for Torsade de Pointes?

Answer: The basis of treatment for Torsade de Pointe is sppression of early afterdepolarizations.

Magnesium is the drug of choice for suppressing EADs and terminating the arrhythmia. This is achieved by decreasing the influx of calcium, thus lowering the amplitude of EADs. Magnesium is effective even in patients with normal magnesium levels.

Some authorities recommend supplemental potassium to increase the potassium concentration to high normal, which increases the efflux of potassium from myocardial cells, thus causing rapid repolarization.

2009-10-24T07:21:00.000-07:00

Saturday October 24, 2009
Medical Trivia

Do you know that -

Coumadin was first approved for medical use in humans in 1954. And a famous early recipient of warfarin was US president Dwight Eisenhower, who was prescribed the drug after having a heart attack in 1955.

Reference: The discovery of dicumarol and its sequels - Circulation. 1959 Jan;19(1):97-107

2009-10-23T18:14:00.000-07:00

Friday October 23, 2009
Dexmedetomidine (precedex) reduce total extubation time?

Giving a patient dexmedetomidine prior to removing respiratory ventilation support reduced the total extubation time, according to research presented at the American Society of Anesthesiologists (ASA) 2009 annual meeting held this week in New Orleans. Researchers also found using the sedative resulted in fewer ventilator days and more successful extubation.

“Currently, if a patient cannot be successfully extubated, no viable alternative exists aside from performing additional weaning attempts and, in some cases, a tracheotomy,” said lead author Julin F. Tang, MD, MS, FCCM, clinical professor, Department of Anesthesia and Perioperative Care at San Francisco General Hospital. “This is tremendously hard on the patient. Now, based on the results of this study, dexmedetomidine may be a viable option for patients who have failed previous attempts to remove the respiratory tubes because it appears to inhibit a stress response in the body that can make it difficult to extubate.”

The prospective, randomized, controlled, IRB-approved study, "Dexmedetomidine Facilitates Extubation in Agitated SICU Patients Failing Previous Weaning Attempts," was conducted among 20 critically ill, intensive care patients who had failed previous attempts to remove ventilation support.

Participants not in the control group received dexmedetomidine at 0.5 or 0.7 mcg/kg/hr. Background sedation and analgesia were gradually decreased in the treatment group, and aerosolized lidocaine was initiated prior to weaning. Shortly after dexmedetomidine infusion, pressure support ventilation (PSV) was initiated and patients were weaned and extubated. Researchers measured the medication treatment group’s condition by checking the subjects’ arterial blood gases at three different points throughout the trial.

Following extubation, the amount of time required to take the tube out was distinctly shorter in patients who received dexmedetomidine. Ventilator time was shorter in these patients, and the rate of successful extubation was higher in the treatment group than the control group.

“Although the study size was relatively small, these results suggest that dexmedetomidine infusion during the weaning process may help control those problems that cause weaning attempts to fail such as agitation, tachypnea, tachycardia, and hypertension,” said Tang. “If a patient has these reactions, the medical team must refrain from pulling out the ventilator tube and try again the next day, which adds to the patient’s hospital costs as well as stress level.”

References: Click to get article

1. Study on the Use of Dexmedetomidine to Facilitate Extubation in Surgical Intensive-Care-Unit Patients Who Failed Previous Weaning Attempts - clinicaltrials.gov

2. Use of dexmedetomidine to facilitate extubation in surgical ICU patients who failed previous weaning attempts following prolonged mechanical ventilation: A pilot study - Respir Care 2006;51 (5):492-496.

3. Feasibility of dexmedetomidine in facilitating extubation in the intensive care unit - Journal of Clinical Pharmacy and Therapeutics, Volume 33 Issue 1, Pages 25 - 30, Published Online: 17 Jan 2008

2009-10-22T09:41:00.000-07:00

Thursday October 22, 2009

Q: What's the basic difference between Phenytoin and Fosphenytoin?

Answer:

Phenytoin (Dilantin) is not water soluble, and must be solubilized in propylene glycol carrier with pH 12 to prepare IV form; therefore, cannot be given more than 50 mg/min without risk of significant hypotension and cardiac arrhythmias. Also major risk of potential irritation at IV site and vascular compromise of infused limb.

Fosphenytoin (Cerebyx) is a phosphorylated phenytoin prodrug. Highly water-soluble and therefore easier to administer than phenytoin. Enzymatically converted to phenytoin after mean 8 min and therefore can be administered more rapidly than standard phenytoin.

2009-10-21T21:18:00.000-07:00

Wednesday October 21, 2009
Statin prophylaxis and inflammatory mediators following cardiopulmonary bypass: a systematic review shows evidence is still missing!

Introduction: Induction of an inflammatory response is thought to have a significant role in the complications that follow cardiopulmonary bypass (CPB). The statin drugs are increasingly being recognized as having potent anti-inflammatory effects and hence have potential to influence an important mechanism of injury in CPB. Our objective was to systematically review if pre-operative prophylactic statin therapy, compared with placebo or standard of care, can decrease the inflammatory response in people undergoing heart surgery with CPB.

Results: Eight RCTs were included in the review, with the number of trials for each inflammatory outcome being even more limited.

Pooled data demonstrated benefit with the use of statin to attenuate the post-CPB increase in interleukins 6 and 8 (IL-6, IL-8), peak high sensitivity C-reactive protein (hsCRP), and tumor necrosis factor-alpha (TNF-a) post-CPB.
Very limited RCT evidence suggests that prophylactic statin therapy may also decrease adhesion molecules following CPB including neutrophil CD11b and soluble P (sP)-selectin.

Conclusions: Although the RCT evidence may suggest a reduction in post-CPB inflammation by statin therapy, the evidence is not definitive due to significant limitations. Several of the trials were not methodologically rigorous and statin intervention was highly variable in this small number of studies. This systematic review demonstrates that there is a significant gap that exists in the current literature in regards to the potential anti-inflammatory effect of statin therapy prior to CPB.

Reference: click to abstract

Statin prophylaxis and inflammatory mediators following cardiopulmonary bypass: a systematic review: Critical Care 2009, 13:R165 (19 October 2009)

2009-10-20T15:46:00.000-07:00

Tuesday October 20, 2009
3 preparations of Propofol

Propofol has 3 products available in market. They each contain different preservatives.

The Hospira brand has Benzyl Alcohol,
the Teva product has Sodium Metasulfite, and
the APP product contains Edetate Disodium

Clinical significance: Some patients have allergies to sulfites so using the Teva product could be of concern in these instances.

2009-10-19T16:22:00.000-07:00

Monday October 19, 2009

Question: What is Empyema necessitans?

Answer: Empyema necessitans is a rare complication of pleural space infections and occurs when the infected fluid dissects spontaneously into the chest wall from the pleural space. This process may result from bronchopleural extension of a peripheral lung infection. These cases result from inadequate treatment of an empyema and usually occur after a necrotizing pneumonia or pulmonary abscess.

XX-year-old male intravenous drug user with "empyema necessitans".
CT image shows empyema and draining chest wall abscess

2009-10-18T22:32:00.000-07:00

Sunday October 18, 2009
Clipping of Cerebral Aneurysm

2009-10-17T21:58:00.000-07:00

Saturday October 17, 2009
Mechanism of Thrombocytopenia and Thrombosis in HIT (Heparin induced Thrombocytopenia)

2009-10-16T14:46:00.000-07:00

Friday October 16, 2009
Bedside trick - suspecting tracheal aspiration!

One quick method of suspecting tracheal aspiration or atleast ruling out tracheal aspiration is checking glucose concentration by regular bedside glucose meters. A glucose concentration of more than 20 mg/dl of bloodless tracheal aspirate doesn't confirm but atleast enhance the suspicion of tracheal aspiration.

Though literature is full of conflicting data for this method but still it is a very quick, effective and easy way of suspecting or ruling out tracheal aspiration.

References: click to get abstracts / articles

1. Clinical implications of the glucose test strip method for early detection of pulmonary aspiration in nasogastric tube- fed patients - Taehan Kanho Hakhoe Chi. 2004 Dec;34(7):1215-23

2. Comparison of blue dye visualization and glucose oxidase test strip methods for detecting pulmonary aspiration of enteral feedings in intubated adults - Chest, Vol 103, 117-121

3. Glucose content of tracheal aspirates: Implications for the detection of tube feeding aspiration. Crit Care Med 1994; 22:1557-1562

4. Glucose Content of Tracheal Aspirates - Letter to the Editor - Critical Care Medicine: Volume 23(8) August 1995 pp 1451-1452

2009-10-15T05:40:00.000-07:00

Thursday October 15, 2009

Q: How Hextend is different from regular 6% hetastarch in 0.9% NS?

Answer: 6% hetastarch in 0.9% NS contains 154 mEq/L of Sodium and 154 mEq/L of chloride along with 6% hetastarch.

Hextand is 6% Hetastarch in Lactated Electrolyte solution with following amounts of electrolytes

Sodium (mEq/L) = 143
Chloride (mEq/L) = 124
Calcium (mEq/L) = 5
Potassium (mEq/L) = 3
Magnesium (mEq/L) = 0.9
Dextrose/ Glucose Units (g/L) =0.99

Hextend also contains 28mEq/L lactate, which acts as a source of bicarbonate in patients with unimpaired lactate metabolism.

Related previous pearls:

Normosol is NOT just Normal Saline
Difference between Lactate Ringer's and Normal Saline solutions

2009-10-14T09:15:00.000-07:00

Wednesday October 14, 2009

Q: What is "cryo reduced plasma"?

A; One unit of cryoprecipitate is derived from one unit of fresh frozen plasma (FFP). Left over FFP, after removal of cryoprecipitate is called supernatant plasma or CRYO-REDUCED PLASMA.Clinical Significance: Cryo-reduced plasma is used as a treatment in plasmapheresis for TTP, not responding to regular plasma exchange with FFP. Some physicians even use it as first line for plasmapheresis/Therapeutic Plasma Exchange (TPE) for a patient with Thrombotic Thrombocytopenic Purpura (TTP).

2009-10-13T06:31:00.000-07:00

Tuesday October 13, 2009

Q: Claviprex (clevidipine butyrate) is a newly approved IV medication for acute hypertension control as a continuous infusion. It is a lipid based drug (like propofol). How many calories it provides per cc via lipid?

Answer: Claviprex (clevidipine butyrate) provides about 2 kilocalories per cc to patient. In contrast, Diprivan (propofol) provides 1.1 kilocalories per ml to patient.

2009-10-12T14:26:00.000-07:00

Monday October 12, 2009
Acetaminophen overdose Nomogram

2009-10-11T17:52:00.000-07:00

Sunday October 11, 2009

Q: While performing cardioversion for atrial flutter, synchronization of electric shock should occur with (Select one)

A) P wave in EKG
B) QRS comples in EKG
C) R wave in EKG
D) T wave in EKG
E) ST segment in EKG

Answer: While performing cardioversion for atrial flutter, synchronization of electric shock should occur to R waves.

2009-10-10T10:30:00.000-07:00

Saturday October 10, 2009
What is Lazarus Syndrome

Lazarus Syndrome is a generic term use in hospitals when patient shows sign of life after clinically declared dead, like a patient that develops vital signs after cessation of resusitative efforts or organ-donation team arrives to find a live person. The syndome is named after bible story in which Jesus brought back to life a dead person named Lazarus from his tomb.

Term became very popular after publication of book "The Lazarus syndrome: Burial alive and other horrors of the undead" (Rodney Davies - 1978).

In recent years, 'Lazarus Syndrome' has also been use for HIV/AIDS patients who feel having new chance of living with new HIV medications.

2009-10-09T22:25:00.000-07:00

Friday October 9, 2009
Increases in Endotracheal Tube Resistance Are Unpredictable Relative to Duration of Intubation

Background: Accumulated secretions after intubation can affect the resistance of an endotracheal tube (ETT). Our objective was to measure extubated patient tubes and size-matched controls to evaluate differences in resistance.

Methods: New ETTs, with internal diameters of 7.0 through 8.5 mm, were tested as controls to establish the resistance of each size group as measured by pressure drop. Measurements were obtained using a mass flowmeter and pressure transducer. Pressure drop was measured at three flow rates.

Seventy-one patient ETTs were evaluated after extubation by an identical method and compared with controls.

Results:
In each control group, pressure drop was tightly clustered with low variation and no overlap between sizes.
A total of 73 to 79% of the patient ETTs had a pressure drop of more than 3 SDs of size-matched controls at all flow rates.
Pressure drop in 48 to 56% (across three flow rates) of extubated tubes was equivalent to the next smaller size of controls.
At 60 and 90 L/min, 10% and 15% of patient tubes, respectively, had the pressure drop of a control tube three sizes smaller.
The pressure drop was unpredictable relative to the duration of intubation.

Conclusions:

Organized secretions can significantly increase resistance as measured by the pressure drop of ETTs.
The degree of change was highly variable, occurs in all sizes, and was unrelated to the duration of intubation.
The performance of an ETT may be comparable to new tubes one to four sizes smaller.

This may impact the tolerance of ventilator weaning.

References: Click to get abstract/article

Increases in Endotracheal Tube Resistance Are Unpredictable Relative to Duration of Intubation - CHEST October 2009 vol. 136 no. 4 1006-1013

2009-10-08T07:45:00.000-07:00

Thursday October 8, 2009
Hemodialysis in Salicylate overdose with normal level

Hemodialysis is recommended in salicylate overdose patients with a level at or above 100 mg/dL (cut it to half if history suggest chronic ingestion). But if there is any sign of neurological manifestation, dialysis is indicated despite normal level.
Salicylate cause "neuroglycopenia" (lower CNS glucose level) despite normal serum glucose. As patient gets more and more acidotic, salicylate enters CNS and by direct effect cause neuroglycopenia.

7 indications of Hemodialysis in Salicylate poisoning

Mental status change
Pulmonary edema
Cerebral edema
Associated or with renal failure
Level at or above 100 mg/dL(half if chronic ingestion)
If fluid overload prevents alkalinization.

Patient continue to deteriorate clinically.

References: Click to get abstract/article

1. Toxicity, Salicylate - please register free at emedicine.com

2.An evidence based flowchart to guide the management of acute salicylate (aspirin) overdose -Emerg Med J 2002; 19:206-209

2009-10-07T10:13:00.000-07:00

Wednesday October 7, 2009
Vasoconstrictor extravasation

Antidote for vasoconstrictor extravasation in skin and tissues (dopamine, epinephrine, or norepinephrine) is PHENTOLAMINE. Infiltrate 5-15 mg of PHENTOLAMINE in 10 ml of normal saline into the area of extravasation as soon as possible. Treatment may be applied and effective up to 12 hours post extravasation of vasoconstrictor. Keep yourself ready for fluid bolus post treatment.

Mechanism of action: Phentolamine is a nonspecific alpha-adrenergic blocking agent which inhibits vasoconstriction and allow improved blood circulation through the affected area.

References: Click to get abstract or article

1. Treating Extravasation Injuries - extravasation.org
2. The use of phentolamine in the prevention of dopamine-induced tissue extravasation - J Crit Care 1998 Mar;13(1):13-20

2009-10-06T14:15:00.000-07:00

Tuesday October 6, 2009
Sympathetic Storming

Sympathetic storming after traumatic brain injury remains one of the most dramatic clinical scene particularly in neurological units. It occurs due to uncontrolled sympathetic surge with a diminish or unmatch parasympathetic response. Acording to Baguley criteria 5 out of the 7 clinical features should be present -

tachycardia,
tachypnea,
hyperthermia,
hypertension,
dystonia,
posturing, and
diaphoresis

Various agents have been used for treatment (see review article below) but haloperidol may worsen the symptoms.Dr. Blackman and coll. coined the term "PAID" - paroxysmal autonomic instability with dystonia- in Archives of Neurology March 2004.

References: click to get abstract/article

1. Dysautonomia after traumatic brain injury: a forgotten syndrome? - J Neurol Neurosurg Psychiatry 1999;67:39-43 ( July )
2. Pa roxysmal autonomic instability with dystonia (PAID) - Arch Neurol. October 2004;61:1625.
3. Paroxysmal Autonomic Instability with Dystonia After Brain Injury - Arch. Neurol. March 2004;61:321-328

2009-10-05T15:50:00.000-07:00

Monday October 5, 2009
Patients who code while on pressors have low chance of survival

Following pearl contributed by:

Tony Halat, MD
Clinical Instructor in Medicine Department of Medicine,
The Methodist Hospital
Weill Medical College, Cornell University

A small retrospective study looked at the outcome of patients who code in the ICU, including those who were on pressors prior to the code.

In this group of patients only 17% of all those who coded survived to discharge and only 4% of those already on vasopressors at the time of code survived. Interestingly the patients comprising the 4% all had underlying conditions amenable to intervention (myocardial infarction, aortic dissection).

The study concluded that the administration of vasopressors prior to the code strongly predicted non survival.

Reference: click to get article

Outcomes of cardiopulmonary resuscitation for patients on vasopressors or inotropes: A pilot study - Journa of Critical Care - Volume 24, Issue 3, Pages 415-418 (September 2009),

2009-10-04T09:22:00.000-07:00

Sunday October 4, 2009
Call for dialysis in Lithium overdose

Call for Hemodialysis in Lithium toxicity is "clinical" depending on symptoms particularly neurological symptoms such as myoclonus, seizure, confusion or coma. There is no laboratory cutoff value as patient with chronic exposure to lithium may show clinical signs at much lower value. Also some recent data favors CVVHD (or HD followed by CVVHD) as it showed to prevent rebound of lithium serum concentration.

To dialyse or not to dialyse… - pwr point presentation - S. Gosselin, MD

Reference:

HD followed by continuous hemofiltration..: Am J Kidney Dis. 2001 May;37(5):1044-7

2009-10-03T21:24:00.000-07:00

Saturday, October 3 2009
Propofol and Green urine

Propofol infusion is noticed to turn colour of urine green. It is a benign potential side effect of Propofol. Recognition of this side effect is important as it averts unnecessary further workup and limits medical expenditures.

2009-10-02T20:06:00.000-07:00

Friday October 2, 2009

Following pearl contributed by:

Tony Halat, MD
Clinical Instructor in Medicine
Department of Medicine, The Methodist Hospital

Weill Medical College, Cornell University

Limited codes do not work
There is no such thing as soft code

A study looked at the outcome of limited codes in which certain treatments were intentionally not provided versus full ACLS protocol codes. These limited codes had a much lower survival rate than those run with no such limitations (29.4% vs 58.6% p=0.023)

The authors concluded that limited codes have lower rates of survival and this information should be conveyed to patients and families when making decisions about code status.

Reference: click to get abstract

Analysis of limited resuscitations in patients suffering in-hospital cardiac arrest - Resuscitation. 2009 Sep;80(9):985-9. Epub 2009 Jul 5

2009-10-01T15:51:00.000-07:00

Thursday October 1, 2009
Clonidine and Bradycardia!

Clonidine is a alpha adrenergic agonist with sympatholytic activity and has been used for various clinical indications beside blood pressure control including treatment for migraines, menopausal complaints, narcotic and alcohol withdrawal symptoms, spasticity after spinal cord injury, attention-deficit hyperactivity disorder as well as rate control for atrial fibrillation.

Mechanism of action: Symptomatic bradycardia is a side effect of clonidine which many times go ignored. Clonidine's central effect results in decreased sympathetic outflow and enhanced vagal tone, lowering blood pressure and heart rate. This also cause side effects of drowsiness, lethargy and dry mouth. Clonidine acts peripherally within the heart to inhibit norepinephrine release, contributing to further reductions in heart rate.

Risk factors: Patients at higher risk for clonidine-induced bradycardia seem to be those with an already-diseased conduction system, renal failure, high doses of clonidine, concomitant therapy with medications known to cause bradycardia or heart block, (eg, beta-blockers, verapamil, diltiazem, digoxin).

Treatment: For severe, symptomatic bradycardia, atropine can be used. For refractory symptomatic cases, isoproterenol, epinephrine, dopamine, and pacing may be required.