Learning Critical Care Medicine

Reverse triggering is a recently defined type of double triggering where a controlled mechanical breath, stimulates receptors in the lung, eliciting inspiratory effort. Seen in patients who are deeply sedated with high mechanical ventilation rates. Reverse triggering could be explained by respiratory entrainment, a form of patient ventilator interaction, where diaphragmatic muscle contraction is triggered by ventilator insufflations, leading to breath initiation. Consequences of reverse triggering are large. Continuously induced muscle contraction of diaphragm cause cytokine release and muscle fibre damage. Additionally it increases inspiratory muscle load and oxygen consumption and may lead to cardiovascular instability. Reverse triggering also makes measurement of plateu pressure misleading as well as may generate high platue pressure and ventilator induced lung injury. Management is not entirely clear. Increasing sedation does not help. Increasing inspiratory time will cause the

● Estimating correct size of suction catheter-    ▪Suction catheters are measured in FRENCH units, which refers to Circumference of the tube,    ▪ C= 3.1416 × D  ( C= circumference,  D= diameter),    ▪ Circumference is nearly 3 times Diameter,    ▪ Endotracheal/ Tracheostomy tubes are measured in DIAMETER,       ▪ Suction catheter size should be limited to not more than half the size of ET/TT,    ▪ Multiply ET/TT size by 3( converting it into French unit), now divide this number by 2, you get suction catheter size,    ▪ Example-  if ET size is 8: 8×3=24; 24/2=12; Suction catheter size is 12.

▪Negative pressure generated during first 100 ms of an occluded inspiration, ▪Measure of neuromuscular drive to breath, ▪measure of Neurogenic drive as well as respiratory muscle power, ▪Normal value: 1.5-2.5 cm HO ▪P 0.1 > 2.5 translates to increased Neurogenic drive to breath due to increased WEB ( work of breathing), ▪Therefore high P. 1 reflects high chances of weaning failure due to respiratory muscle fatigue. ▪P. 1 < 1.5 indicates decreased Neurogenic drive or neuromuscular weakness. ▪P. 1 may be low because of high ventilator support (WOB beared by ventilator, patient being passive).

▪Inappropriate adduction of true vocal cords, mostly during inspiration. This results in dyspnoea and strider during inspiration. Rarely it may happen during expiration also. ▪15 Y F presenting with acute respiratory distress for 48 hours. For the past 2 years she was on inhaled bronchodialtors and steroids with short cources of oral/IV steroids for bronchial asthma. There was history of 4 hospital admissions and several emergency visits for symptoms attributed to asthma. Examination revealed apprehensive, tachycardic, tachpnoic girl with accessory muscle use and widespread rhonchi bilaterally, SPO2 93% on room air. Other systemic examination were normal. She was started on inhalation therapy but her conditioned worsened. Oxygen saturation felled to 78% ON 10 L face mask,  ABG revealed pH 7.53, PaO2 58, PaCO2 28. She was intubated emergency and shifted TO ICU. She was treated as life threatening attack of bronchial asthma. She improved dramatically and successfully extubated in 48 h

Shared from Facebook page Learning Critical Care Medicine (posted on 18th May 2015). " marte hain aarjoo me marne ki   maut aati hai par nahi aati "                 - Mirza Ghalib Aruna Shanbaug officially died today at KEM hospital Mumbai. She was in Permanent Vegetative State (PVS) for the last 42 years. During these years she had become a living skeleton, though she pulled through this long because of effort, love and care of her fellow nurses. She did not develop a single pressure sore. Infrequently miss Shanbaug used to transform into news headlines as she became synonym for End of Life Care debate in India during last many years. As there was no clear law regarding End of Life Decision ( EOLD) in India, public interest litigation was filed in 2009 in Supreme Court to relieve Aruna of her sufferings. Court arrived to verdict in 2011, affirming that Aruna is in PVS. Decision to withdraw life support measures can be taken by parents/ spouse/ close relatives or in th

▪ Decreased glutathione store, increased activity of gamma glutamyl cyclotransferase is increased, key enzyme in gamma glutamyl cycle. This results in pyroglutamic (oxoproline) acid accumulation. ▪ Conditions associated:       -Chronic paracetamol use       -Chronic ethanol abuse       -Malnutrition       -Pregnancy       -Congenital enzyme deficiency       -Hepatic and renal impairment       -Sepsis       -Drugs: Flucloxacillin,  Netilmycin, Vigabatrin ▪80 Y F presents in ER with lethargy and dizziness. Past medical history revealed chronic back pain treated with paracetamol and ibuprofen. She also takes ramipril for Hypertension. Examination suggested chronically ill, arousal and awake patient. BP 150/65, HR 72, RR 32, SPO2 98% on room air. Other systemic examination was unremarkable. Lab revealed normal CBC , Na 138, K 3.6, Cl 98, HCO3 9, lactate 1.2, Glucose132, AST 65, ALT 75, Normal ammonia,  BUN 30, Creatinine 1.5. Toxicology result showed acetaminophen level less t

● QUORUM SENSING : Mechanism by which bacteria communicate with one another. Purpose is to ensure that sufficient cell number, of a given species is present, before initiating a response. A single bacterial cell secreting a toxin into a host organism, is not likely to do harm and would waste resources. However, in large population, a coordinated expression of toxin is most likely to result in desired harm. Bacteria use quorum sensing, to coordinate certain behavior like Biofilm formation, Virulence and Antibiotic resistance. It is achieved by secreting autoinducer by individual bacteria. When an autoinducer reaches a certain threshold, bacteria detects and responds by altering gene expression. ● QUORUM QUENCHING : Process of preventing quorum sensing by disrupting the signal. Breaking the quorum sensing or utilizing quorum quenching, biofilm formation can be minimized, bacterial Virulence and resistance can be controlled.

"The future of humanity and microbes will likely evolve...As episodes of our wits versus their genes."              - Dr. Joshua Lederberg ESBL ( EXTENDED SPECTRUM BETA LACTAMASES ) CRE ( CARBAPENEM RESISTANT ENTEROBACTERIACAE ) VRE ( VANCOMYCIN RESISTANT ENTEROCOCCI ) MRSA ( METHICILLIN RESISTANT STAPH. AUREUS ) VRSA ( VANCOMYCIN RESISTANT ENTEROCOCCI ) ESKAPE organisms - Enterococcus faecium, Staph. aureus,  Klebsiella pneumonae, Acinatobacter, Pseudomonas aeriginosa, Enterobacter. No ESKAPE,  BAD BUG NO DRUG, 10×20 Initiative- IDSA: Development of 10 new drugs by 2020. ANTIBIOTIC STEWARDSHIP : optimal Selection, Dose and Duration of antimicrobial treatment that results in best clinical outcome, for the treatment of infection, with minimal Toxicity to patient and minimal impact on subsequent Resistance. 4 D of antimicrobial therapy : Right drug, Right dose, Right duration, Deescalation.

""The rationale use of antibacterial drugs should be based on two principles. First, the specific identify of the infecting organism must be determined. Second, a test must be devised which will provide an accurate estimate that the antibiotic will be effective in vivo."             -Petersdorf and Plorde, 1963 ●90 60 RULE: Infection caused by a susceptible isolates respond to appropriate antimicrobial approximately 90% of time, whereas infections caused by resistant isolates actually respond to inappropriate antimicrobial about 60% of the time. This variability is observed probably because, the in vitro antibiotic sensitivity test do not take into account Pharmacokinetic/ Pharmacodynamic (PK/PD) properties. Also the microbial load at the site of infection is different than that in testing. ●ANTIBIOGRAM: Periodic summary of antimicrobial sensitivity of local bacterial isolates,  submitted to the hospital's clinical microbiological laboratory, used to asses