Question

Hemodynamic Vent (Question 6)

Patient Profile

R.B. is a 55-year-old woman who presented to the emergency department (ED) via ambulance for acute shortness of breath. Her daughter called an ambulance after finding her mother with an increased respiratory rate and shortness of breath. Upon arrival to the ED, R.B.’s respirations were 40 and shallow with wheezing in the lower lobes and rhonchi in the upper lobes bilaterally. She had positive jugular vein distention and a heart rate of 128. After treatment with albuterol nebulizer via mask, her vital signs were temperature 96.8˚F, pulse 98, respirations 28, blood pressure 148/84, and O₂ saturation 94% with 15 LPM via mask. Arterial blood gasses showed her pH 7.19, pCO₂ 90, PO₂ 92%, HCO₃ 38. R.B. was intubated for hypercapnia. After an echocardiogram showed an ejection fraction less than 50%, she had an emergency left heart catheterization done with two stent placements into the left anterior descending artery. A pulmonary artery catheter was placed, and the initial hemodynamic readings show elevated left ventricular preload. R.B. is now being transferred to the intensive care unit (ICU).

Subjective Data

• Lives with her single daughter, who cares for D.B. full time
• Daughter is not present at bedside
• Smokes 1 pack of cigarettes per day
• No longer active outside of the home because of her chronic illness
• Does not drink alcohol

Objective Data

Physical Examination

• Orally intubated #8 endotracheal (ET) tube taped at 26 cm to lip
• Ventilator settings: FIO₂ 60%, tidal volume 700, assist control (A/C), rate 16, PEEP of 5
• Height 5’5”,weight 117 kg
• Alert and oriented to person, place, and time
• Fine crackles and wheezes bilateral lower lobes
• 2+ pitting edema bilateral lower extremities

Diagnostic Studies

• Chest x-ray postintubation: ET tube 4 cm from carina. Infiltrates in both bases; left base is worse than right
• 12-lead ECG: ST elevation
• Troponin: 41.94
• Lung V/Q scan negative for pulmonary embolism
• Urinalysis: dark yellow and cloudy, protein 28 mg/dL, positive for casts, positive for red blood cells and white blood cells, positive for glucose and ketones

Discussion Questions

6) Describe each of R.B.'s ventilator settings and the rationale for the selection of each.

• Ventilator settings: FIO₂ 60%, tidal volume 700, assist control (A/C), rate 16, PEEP of 5

Answer 1

In ventilated patient , Oxygenation can be achieved by increasing the fraction of inspired oxygen (FIO₂) or the Positive end expiratory pressure (PEEP).

Mechanical ventilator :

Assist- control (A/C) modes of ventilation are modes that maintain a minimum respiratory rate regardless of whether or not the patient intiates a spontaneous breath.In this, pressure and volume are directly linked by the pressure-volume curve.

in Mechanical ventilated patient , the CO2 content of the blood can be modified by changing the tidal volume or the respiratory rate.

Tidal volume: It means the volume of air moved in and outside the lungs in each respiratory cycle.Too high volume risks for Overinflation and too low volume allows for Atelectasis.

Tidal volume and Respiratory rate set the minute ventilation.

Positive end expiratory pressure (PEEP) : The positive pressure will remain in the airways at the end of the respiratory cycle (end of exhalation) that is greater tahn the atmospheric pressure in mechanically ventilated patients.

Fraction of inspired oxygen (FIO₂) : It means the percentage of oxygen in the air mixture that is delivered to the patient.It is an estimation of the oxygen content a patient inhales and it is involved in gas exchange at the alveolar level.  

Most patients undergoing mechanical ventilation may benefit from applying PEEP at 5cm H₂o to limit Atelectasis. Higher levels of PEEP improve oxygenation disorders like Cardiogenic pulmonary edema. PEEP allows use of lower levels of FIO₂  while maintaining adequate atrial oxygenation.

FIO_{2 :} At the starting of intubation on ventilator should always maintain FIO₂ at 100% untill to get adequate oxygenation. it is maintained at 100 % level to protect patient from Hypoxemia and other unrecognised diagnosis. after sometime  FIO₂ should be quickly tritrated down to the minimal level required to maintain adequate oxygenation levels. Normal level is 50% or slight above.

in healthy human being normal tidal volume is 500ml per inspiration. Tidal volume is calculate by multiplying a volume factor by the body weight in Kgs .

Tidal volume = 6 117 Kg

= 700 ml

the normal respiratory rates for adult at normal rest range is 12 to 16 breaths per minute. The rate 16 means R.B is breathing at noramal rate .  Too high a rate risks for Hyperventilation and Respiratory alkalosis along with inadequate expiratory time and too low a rate risks for inadequate minute ventilation and Respiratory Acidosis.

PEEP is normal range is 5cm H2O has to maintain oxygenation levels with FIO2 60%.