Friday February 27, 2009

Scenario: You have a patient with intracranial bleed. ICP monitor has been inserted by neurosurgical service. You have been asked by nurse to clarify confusion about the level of transducer for Mean Arterial pressure (MAP), so correct CPP (Cerebral Perfusion Pressure) can be calculated. What is the answer?


Answer: To calculate CPP, tansducer should be "zeroed" at the height of the head to calculate MAP. There is a misconception that transducer should always be leveled / zeroed at heart level. Its not true. For Cerebral Perfusion Presuure calculation, MAP should be calculated with transducer at head (or ear) level.

Cerebral Perfusion Pressure (CPP) is defined as the difference between the Mean Arterial Pressure (MAP) and the Intracranial Pressure (ICP).

CPP = MAP - ICP

Wednesday February 25, 2009
r-PA in massive PE

Q: For massive PE, fibrinolytic regimens currently in common use include 2 forms of recombinant tissue plasminogen activator, t-PA (alteplase) and r-PA (reteplase). What advantage does r-PA has over t-PA?


Answer: Reteplase (r-PA, Retavase) is a second-generation recombinant tissue-type plasminogen activator. As fibrinolytic agent, it seems to work faster than its forerunner, t-PA (alteplase), and also may be more effective in patients with larger clot burden. Also has been reported more effective than other agents in lysis of older clots. Two major differences help explain these improvements.

1. Compared to alteplase, reteplase does not bind fibrin so tightly, allowing drug to diffuse more freely through clot.
2. Reteplase does not compete with plasminogen for fibrin-binding sites, allowing plasminogen at site of clot to be transformed into clot-dissolving plasmin.

Dose is two 10-U IV boluses, given 30 min apart. In setting of cardiac arrest or impending arrest due to PE, single IV bolus of 20 U can be used.

Monday February 23, 2009

Q: What happen to surfactant in ARDS?


Answer: Normal lung expansion is accomplished by inspiratory muscle contraction generating a negative pleural pressure, which in turn, inflates the lung but lung mechanical properties resist inflation due to the inherent elasticity of lung tissue and the airway resistance. An important feature in all mammalian lungs is the presence of surface-active lining material in the alveoli, called surfactant. Surfactant greatly reduce the surface tension of the alveolar membrane and, as a consequence, allow the lung to inflate with relatively small transpulmonary pressure generations. In addition, surfactants have important anti-inflammatory properties.

Interestingly, In ARDS, the total amount of surfactant present in the lung may actually be elevated! However, type 2 cell injury in ARDS alters surfactant metabolism/recycling and the surfactant that is produced is often dysfunctional. As a consequence, surface tension in the alveoli of patients with ARDS is usually markedly elevated. This contributes to the poor compliance and ventilation-perfusion mismatch seen in ARDS. It may also be a factor in reduced host defenses with the loss of surfactant anti-inflammatory processes.

Saturday February 21, 2009
Risk factors for increase mortality in ICU Asthmatic patients


One review of 2152 ICU admissions with Asthma showed that

• Older age,
• female sex,
• having received CPR within 24 hours before admission,
• having suffered a neurological insult during the first 24 hours in the ICU,
• higher heart rate, and
• hypercapnia

were associated with greater risk for in-hospital death.

Lesson Learned: Early intervention (including intubation) in Asthma patients is key in decreasing mortality.

Reference: Click to get abstract

Characteristics and outcome for admissions to adult, general critical care units with acute severe asthma: a secondary analysis of the ICNARC Case Mix Programme Database -Critical Care 2004, 8:R112-R121

Thursday February 19, 2009

Q; You received following CT scan report on a patient

"The peripheral opacities are present in the form of triangles, with the base of the triangle along the pleural surface and the tip of the triangle toward the mediastinum"

What would be your diagnosis in patient with cough, fever, dyspnea, hemoptysis and hypoxia?

Answer: Bronchiolitis Obliterans Organizing Pneumonia (BOOP)

The chest computed tomographic scan shows findings similar to the chest radiograph in BOOP, with bilateral areas of consolidation and ground glass opacities, usually with a peripheral location (figure 2B). Not always but sometimes the peripheral opacities are in the form of triangles, with the base of the triangle along the pleural surface and the tip of the triangle toward the mediastinum (figure 2C).



Reference: click to get abstract

Bronchiolitis obliterans with organizing pneumonia: outcome. - Thorax, 1995;50(suppl 1):S59-S64

Wednesday February 18, 2009


Q; What's your diagnosis?





Answer: Chest x-ray of a large bulla with infection in a patient with Bullous emphysema; showing fluid level

Tuesday February 17, 2009
Induced mild hypothermia for post-cardiopulmonary bypass vasoplegia syndrome?


Interesting article....

Cardiopulmonary bypass (CPB) technique used for open-heart surgery exposes patients to numerous adverse effects. Vasoplegia syndrome (VS) is one such, reported in the early postoperative period of CPB in cardiac surgery. It commonly presents with generalized profound vasodilatation resulting in the decreased systemic vascular resistance (SVR) and hypotension despite adequate cardiac output (CO). There is decreased arteriolar reactivity towards vasoconstrictors, increased need for filling volume and vasopressor agents. A release of proinflammatory cytokines leading to inflammatory response is the major contributing factor.

In this article, authors induce mild hypothermia (core temp 34°C) by surface cooling using hypo-hyperthermia blanket. After 60 min of institution of mild hypothermia, SVR gradually improved along with normalization of cardiac output, decreased heart rate, and increased mean arterial blood pressure. Patient is rewarmed gradually in the next 4 hours. Arterial blood oxygenation also improved significantly (PaO 2 - 126 mmHg at FiO 2 of 0.5) with the use of hypothermia.

Read full article: Induced mild hypothermia in post-cardiopulmonary bypass vasoplegia syndrome (Ann Card Anaesth, Year : 2009, Volume : 12, Issue : 1 , Page : 49-52)

Monday February 16, 2009

Q: How supplemental oxygen helps in accelerating the resolution of a pneumothorax?


Answer: oxygen may speed resolution of the pneumothorax by increasing the gradient for nitrogen absorption. Resolution of pneumothorax has shown increase rate of absorption if oxygen supplement is increased from a lower concentration via nasal cannula to a partial rebreathing mask. Oxygen therapy results in a fourfold increase in the mean rate of absorption. This fact is known since last 40 years and still applicable and easy to do 1. During inhalation of room air the total gas pressure in blood from the distal end of a capillary is about 706 mm Hg, whereas during inhalation of 100% oxygen it is about 146 mm Hg. This difference is mainly due to a reduction in partial pressure of nitrogen from 573 mm Hg to a zero - and can be accompanied by an increase in the partial pressure of oxygen in arterial blood from 100 to 640 mm Hg. oxygen utilization in the tissues ensures that the partial pressure of oxygen in end-capillary blood rises only slightly from 40 mm Hg to about 53 mm Hg.

Pneumothorax during needle lung biopsy can be prevented by breathing 100% oxygen 2.



References: click to get article

1. Oxygen Therapy for Spontaneous Pneumothorax - Br Med J. 1971 October 9; 4(5779): 86–88.
2. Prevention of pneumothorax in needle lung biopsy by breathing 100% oxygen - Thorax. 1980 January; 35(1): 37–41.

Sunday February 15, 2009

Q: What is the classic Beck triad of pericardial tamponade?


Answer:

• hypotension,
• muffled heart sounds,
• jugular venous distension

Saturday February 14, 2009

Q: What position is recommended for intubation in pregnant patient ?


Answer: Ear to Sternal Notch Positioning

In pregnancy, a wedge made of blankets or towels may be placed under the right hip to displace the uterus laterally and facilitate venous return to the heart or an assistant may displace the uterus manually. Ear-to-sternal notch position is prefered in pregnant and morbidly obese patients to improve alignment of the pharyngeal, oral, and laryngeal axes and maximize the laryngoscopic view.

RELATED VIDEO: Rapid aiway management positioner (RAMP)

RELATED ARTICLE: Emergency Airway Management in the Pregnant Patient

Friday February 13, 2009
Friday is our pediatric pearl day

Does N-terminal pro-brain natriuretic peptide (N-proBNP) and troponin I (TnI) profile following mitral and/or aortic valve surgery in children correlate with echocardiography measures and outcome criteria?

In a prospective cross-controlled study in twenty children with acquired valvular disease requiring valvular surgery N-proBNP correlated with the Pediatric Heart Failure Index, left ventricle shortening fraction, left atrium to aorta ratio, left ventricle mass index, end-systolic wall stress, and with outcome measures such as inotropic score, duration of inotropic support, and ICU length of stay. Preoperative N-proBNP was significantly more elevated in patients with complicated outcome than in patients with uneventful postoperative course.

Conclusion: In pediatric valvular patients, perioperative N-proBNP is a promising risk stratification predicting factor. It is correlated with evolutive echocardiographic measures, need for inotropic support, and ICU length of stay.

BNP could be used as marker of heart failure in conjunction with other measures such as echocardiographic finding and clinical severity of illness while explaining parents about short term outcome after surgery such as length of intensive care, need for inotrope support etc.


Reference: click to get reference

Value of brain natriuretic peptide in the perioperative follow-up of children with valvular disease.- Intensive Care Med. 2008 Jun;34(6):1109-13.

Thursday February 12, 2009

Case: How Fondaparinux (Arixtra) is different in Mechanism of action from heparins (unfractionated and low molecular weights), which may give it advantage of not causing HIT (Heparin induced Thrombocytopenia)?


Answer : Fondaparinux (ARIXTRA) is the synthetic Factor Xa inhibitor. While other antithrombotics may inhibit multiple factors in the coagulation cascade, Fondaparinux selectively inhibits only Factor Xa. Fondaparinux is not a heparin. Fondaparinux is the pentasaccharide antithrombotic agent inhibiting only factor Xa.

Wednesday February 11, 2009
Hydroflouric acid exposure

Case: 23 year male while working in the refinery while disconnecting the hose was exposed to hydrofluoric acid. Patient had inhalation of hydrofluoric acid. Patient had no past medical history. Which of the following should be done first?

a. Albuterol nebulizer with 2.5 mg albuterol
b. Albuterol nebulizer with 10mg albuterol
c. Calcium gluconate nebulizer treatment
d. 10% mucomyst treatment



Answer : C

Calcium gluconate should be used after hydrofluoric acid exposure, and if there are any skin lesions it should be applied there too. Patient should be observed for 24-48 for development of pulmonary edema. Ionized calcium should be monitored very closely, and should be supplemented with intravenous calcium gluconate if low.


Related article: Medical treatment for Hydroflouric acid exposure (pdf)

Tuesday February 10, 2009

Q: In Hypothermia induced Ventricular fibrillation which cardiac medicine is preferred and which one may harm the patient?


Answer: Bretylium (5 mg/kg initially) is recommended for any hypothermic patient manifesting significant new frank dysrhythmia. However, bretylium has a worldwide shortage and may not be available. Relying on Amiodarone or Lidocaine are the next choices.

Procainamide may induce more ventricular fibrillation and should be avoided.

Defibrillation should also be performed simultaneously. Defibrillate at 2 J/kg (or the biphasic equivalent) if patient remains in ventricular fibrillation or ventricular tachycardia. Success rates of defibrillation are low if the core temperature is less than 32°C and should be performed with rise in body temperature. Actually, because many arrhythmias convert spontaneously upon rewarming, aggressive therapy of minor arrhythmias is not warranted. Transient ventricular arrhythmias should be ignored. This also is true of bradycardia or atrial arrhythmias.

The cornerstone of treatment is rewarming the patient.

Monday February 9, 2009

Case: 68 year old male presented to ER with left sided weakness and CVA (stroke) is suspected. Patient has chronic history of atrial fibrillation and is on coumadin 4 mg every day and record shows previously consistent therapeutic INR of 2.6 but today patient's INR is 1.4. According to wife, patient is very compliant with his medicines, rather he is very health conscious and lately start doing more healthy diet consist of frequent green tea, fish oil, ginseng, canola oil etc.


Answer: Green Tea carries a huge amount of Vitamin K. It is also present in clinically significant amount in other healthy diets and herbals like fish oil, ginseng, canola oil etc.

Related Web site: WarfarinDosing.org

Its a free Web site to help doctors begin warfarin therapy by estimating the therapeutic dose in patients new to warfarin. This site is supported by the Barnes-Jewish Hospital at Washington University Medical Center, the NIH, and donations. Estimates are based on clinical factors and (when available) genotypes of two genes: cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase (VKORC1).

Sunday February 8, 2009


Case: 48 year old male presented to ER with Shortness of Breath. CXR showed massive left sided pleural effusion. ER physician inserted chest tube but to surprise white milky fluid get drained from chest. You made diagnosis of "Nontraumatic" Chylothorax. What are the 5 major causes of "Nontraumatic" Chylothorax?


Answer:

1. Lymphoma
2. cirrhosis,
3. tuberculosis,
4. sarcoidosis,
5. amyloidosis

Lymphoma is the most common cause of "Nontraumatic" Chylothorax, representing about 60% of all cases, with non-Hodgkin lymphoma more likely than Hodgkin lymphoma to cause a chylothorax. Trauma is the second leading cause of chylothorax (25%) including iatrogenic injury to the thoracic duct with thoracic procedures.

Pseudochylothorax: Chylothorax must be distinguished from pseudochylothorax, or cholesterol pleurisy, which results from accumulation of cholesterol crystals in a chronic existing effusion. The most common cause of pseudochylothorax is chronic rheumatoid pleurisy, followed by tuberculosis and poorly treated empyema.

There were no pearls from February 1 to 7, 2009

- as our server was down