Extubation criteria :

Most parameters of respiratory mechanics are useful only for predicting successful SBT and perform moderately or poorly with extubation prediction. We therefore present a brief discussion of these parameters.

Rapid shallow breathing index (RSBI - f/V _T )
Capdevila ^[16] found significantly lower values of f/V _T (50 ± 23 vs. 69 ± 25 breaths/min/l) in successfully extubated patients. Recently a cut off value of RSBI ≥ 57 was described ^[22] to separate patients who could not be extubated successfully. Epstein, ^[27] however, found that with f/V _T < 100, 14 (of 84) patients failed extubation, 13 due to other organ system problems and suggested that f/V _T was not physiologically suited to predict extubation failure. Other studies ^{[2],[20],[29]} have also reported inability of f/V _T for predicting extubation outcome.

Airway occlusion pressure at 1 s (P _0.1 ) and Ratio of occlusion pressure to maximum inspiratory pressure (MIP) [P _0.1 /MIP] 

P _0.1 /MIP is an index of balance between respiratory reserve and demand and reflects neuromuscular drive for breathing and it is unaffected by respiratory compliance or resistance. Capdevila and colleagues ^[16] reported that patients with low P _0.1 and P _0.1 /MIP failed extubation, Mergoni and colleagues ^[30] reported excellent prediction of success in weaning using P _0.1 /MIP, while Del Rosario ^[31] found similar P _0.1 /MIP values in patients with weaning success and failure. In a metaanalysis, ^[26] P _0.1 /MIP ratio of >0.3 had a pooled likelihood ratio of 2.3, indicating increased chances of successful extubation. Despite excellent predictive accuracy, the role of P _0.1 /MIP ratio may be limited in most ICUs due to need for a special device.

Minute ventilation recovery time (V _E RT) 

Minute ventilation recovery time (V _E RT) allows physiologic assessment of work imposed after SBT. Thus V _E RT may identify patients with better respiratory muscle reserve, capable of sustaining spontaneous breathing following extubation. Martinez and colleagues, ^[2] after a 2-h SBT, placed patients back on their pre-SBT ventilator settings for up to 25 min and measured various respiratory parameters including minute ventilation (V _E ) at three intervals: baseline over preceding 24 h (pre-SBT), post-trial (after SBT) and recovery (return to baseline). Patients were assumed to recover when V _E decreased to 110% of the predetermined baseline. V _E RT of patients with successful extubation was significantly shorter than those who failed extubation (3.6 ± 2.7 min vs. 9.6 ± 5.8 min, P < 0.011). On multivariate analysis, V _E RT was an independent predictor of extubation outcome and correlated with ICU LOS ( P < 0.01). Prolonged V _E RT may reflect either a limited respiratory reserve or an unrecognized, underlying disease process. Seymour and colleagues ^[32] evaluated a more practical method. For pre-SBT V _E they collected data in three ways, a 24-h nadir (as in previous study), an 8-h average and the last V _E measurement prior to SBT. They also collected data on V _E RT with threshold of 100% and 110%. They found that both, the 8-h average V _E and immediate pre-SBT value of V _E, were in close agreement with the original method. Similarly 100% threshold for V _E RT also correlated well with 110% threshold. The same group later demonstrated ^[33] the utility of the new method in predicting extubation success. Recently Hernandez and colleagues ^[34] evaluated the utility of close observation of V _E during the recovery phase after the SBT. Both V _E RT RT50% ∆V _E (recovery time needed to reduce V _E to half the difference between End-SBT- V _E and basal V _E ) were significantly lower in successfully extubated patients. They found that a threshold of RT50% ∆V _E of seven minutes was useful to discriminate between extubation failures and successes. V _E RT and derivatives appear to be promising tools, the drawback being their inability to identify patients with possible upper airway compromise.

Work of breathing (WOB) 

Kirton and others ^[35] found that patients who fail SBT due to increased imposed work of breathing (WOB) secondary to ventilatory apparatus and endotracheal tube, but have normal physiological WOB, can be successfully extubated. The same group later showed ^[36] that when physiological WOB ≤0.8 J/l, patients can be successfully extubated. Automatic Tube Compensation (ATC), a form of variable pressure support, was shown ^[37] to improve extubation success by reducing imposed work of breathing. WOB, a promising predictor; remains confined to the research setting due to technical difficulties.

Displacement of liver/spleen 

Diaphragm fatigue results in slower movement and reduced excursion. Jiang and colleagues ^[38] hypothesized that liver and spleen displacement during SBT can be a surrogate of diaphragmatic endurance. In 55 ICU patients, two separate observers measured the displacement of liver and spleen by ultrasonography. Patients were extubated by clinicians blinded to the study results. Patients who were successfully extubated had higher mean values. With a cutoff value of 1.1 cm, the sensitivity and specificity to predict successful extubation was 84.4% and 82.6%. This is a noninvasive test and can be done bedside, but needs expertise.extu

Extubation criteria

1) patient spontaneously ventilating 
2) reversed adequately: sustained tetany w/o fade > 5 sec is one way to do it. 
3) vital signs stable
4) not in stage 2

Book stuff:

RSBI < 100. Respiration rate/tidal volume in Liters.

nif <-20mmhg (you can take off bag and cover hole with hand and have patient suck in while watching pressure gauge

leak test for airway surgeries/long prone case (dunno how useful it is in reality)

Extubation Criteria

Head lift, Grip

NIF < -25 torr

RR < 30

TV > 5 cc/kg

VC > 10 cc/kg

PaO2 > 65 on FiO2 < .40

PaCO2 < 50 torr

Resting MV < 10 l/min

Level of Consciousness OK

Muscle Relaxants OK

TV/RR > 10

7 things to do prior to Extubation: 
Patient either deep or awake
Patient either breathing or easy to ventilate manually
Oral airway in place
Pharynx suctioned
Cuff deflated
Lungs manually inflated with 100% O2
Succinylcholine available.
NEVER extubate a patient without an oral airway in place.  AFTER you extubate a patient, suction the pharynx one more time, put the mask on the patient, keep your right hand on the bag, test for airway patency, and then help them breathe for a while.

A-a gradient

A-a O2 Gradient = [ (FiO2) * (Atmospheric Pressure - H2O Pressure) - (PaCO2/0.8) ] - PaO2 from ABG

Aa Gradient = (150 - 5/4(PCO2)) - PaO2
Normal Gradient Estimate = (Age/4) + 4

The 5 Causes of Hypoxemia, #1-3 have an elevated A-a Gradient:
V/Q Mismatch (ex: PNA, CHF, ARDS, atelectasis, etc)
Shunt (ex: PFO, ASD, PE, pulmonary AVMs)
Alveolar Hypoventilation (ex: interstitial lung dz, environmental lung dz, PCP PNA)
Hypoventilation (ex: COPD, CNS d/o, neuromuscular dz, etc)
Low FiO2 (ex: high altitude)

fondaparinaux

One potential advantage of fondaparinux over LMWH or unfractionated heparin is that the risk for heparin-induced thrombocytopenia (HIT) is substantially lower. Furthermore, there have been case reports of fondaparinux being used to anticoagulate patients with established HIT as it has no affinity to PF-4. However, its renal excretion precludes its use in patients with renal dysfunction.

Unlike direct factor Xa inhibitors, it mediates its effects indirectly through antithrombin III, but unlike heparin, it is selective for factor Xa.^[1]

Heparin

An IV heparin protocol

When intravenous UFH is initiated for DVT anticoagulation, the goal is to achieve and maintain an elevated activated partial thromboplastin time (aPTT) of at least 1.5 times control. Heparin pharmacokinetics are complex, and the half-life is 60-90 minutes. A protocol for IV heparin use is as follows:

• Give an initial bolus of 80 U/kg.
• Initiate a constant maintenance infusion of 18 U/kg.
• Check the aPTT or heparin activity level 6 hours after the bolus, and adjust the infusion rate accordingly.
• Continue to check the aPTT or heparin activity level every 6 hours, until 2 successive values are therapeutic.
• Monitor the aPTT or heparin activity level, hematocrit, and platelet count every 24 hours.

sedation vacation

http://staugustine.com/living/health/2009-12-17/sedation-vacation-valuable-medical-procedure

FiO2 CALCULATIONS

For every 1 L/min of oxygen by NC, you add 3% to the estimated FiO2. So someone on 4L NC is getting about 33% FiO2 (21 + 12). Of course the FiO2 when you are talking about nasal canula is always an estimate, as people are variable in how much they breathe through their mouth. The actual FiO2 can vary quite a bit.

Pulmonary HTN

Based upon a Doppler echocardiographic study, it can be determined if PH is likely, unlikely, or possible [8]:

• PH is likely if the PASP is >50 and the TRV is >3.4
• PH is unlikely if the PASP is ≤36, the TRV is ≤2.8, and there are no other suggestive findings
• PH is possible with other combinations of findings

• Pulmonary hypertension (PH) defined as a mean pulmonary arterial (PA) pressure of greater than 25 mm Hg at rest or greater than 30 mm Hg during exercise, is characterized by a progressive and sustained increase in pulmonary vascular resistance that eventually leads to right ventricular (RV) failure. 

• Diagnosis of PAH requires the presence of pulmonary hypertension with two other conditions. Pulmonary artery occlusion pressure (PAOP or PCWP) must be less than 15 mm Hg (2000 Pa) and pulmonary vascular resistance (PVR) must be greater than 3 Wood units (240 dyn•s•cm⁻⁵ or 2.4 mN•s•cm⁻⁵).

Bronchiectasis

check out the following video for Bronchiectasis CXray...

http://www.youtube.com/watch?v=Kk4x7DPJtRI&feature=player_embedded

Cold air causing cough

One of my friend always complain that her son starts coughing if he is exposed to cold air/windy weather....I saw him coughing even if he passes frozen section in grocery stores....

The cold weather cough can be caused from a couple of sources.

When you breath in cold air, your lungs contract (tighten) just like any tissue does when exposed to cold. Once you come inside and start breathing warm air, the lung tissue rapidly expands. That sudden expansion can cause the cough reflex. It is a similar reaction to what new runners experience when their lungs start to grow and expand. You'll often see new runners chuging along and hacking out a few coughs.


Your body will work as best it can to deal with the sudden change as best as it can. Taking a moment to cool down before heading inside is excellent advice. If you have a garage or somewhere that would serve as a step between the two extreme temps it would be a good place to cool down in. (Assuming there aren't too many fumes from cleaners etc. in there.)

Only other thing that comes to mind is to try and inhale through your nose while you are cooling down. Conchae inside your nose that serve to adjust the temp/humidity of your inhaled breath to a more acceptable level. They also work as a bit of a 'screen' or filter to help keep some of the junk we breathe out of your lungs.

I'm guessing the tea/coffee you drink would assist your upper airway (mouth/nose) in warming the air you inhale by increasing the temperature in those areas.