mechanical ventilator - Nursing Case Study

Pathophysiology

• Primary mechanism: Mechanical ventilation works by positive pressure flow. It pushes air into the lungs when the patient cannot initiate a breath, maintaining oxygenation and removing carbon dioxide from the body. It is set to deliver a specified volume or pressure, depending on the ventilator settings.

• Secondary mechanism: The ventilator also assists with the exchange of oxygen and carbon dioxide in the lungs (gas exchange). It does this by maintaining a positive end-expiratory pressure (PEEP), which helps to keep the alveoli open and prevent collapse, improving oxygenation.

• Key complication: Ventilator-associated pneumonia (VAP) is a common complication. It's an infection that can occur due to the ventilator introducing bacteria into the lungs. Prevention strategies include regular oral care, elevating the head of the bed, and daily "sedation vacations" to assess readiness for extubation.

Patient Profile

Demographics:

72-year-old male, retired construction worker

History:

• Key past medical history: Chronic obstructive pulmonary disease (COPD), 2-time heart attack survivor, hypertension

• Current medications: Albuterol, Atorvastatin, Lisinopril

• Allergies: Penicillin

Current Presentation:

• Chief complaint: Difficulty in breathing

• Key symptoms: Severe shortness of breath, increased heart rate, chest pain, fever, cough with greenish sputum, confusion

• Vital signs: Blood pressure 145/95 mm Hg, heart rate 110 bpm, respiratory rate 28 breaths per minute, oxygen saturation 88% on room air, temperature 38.2°C

Section 1

Change in Patient Status:

During the early hours of the morning, the patient's condition worsened. The nurse on duty noted an increase in his respiratory rate to 35 breaths per minute and a decreased oxygen saturation level of 82%, despite being on the ventilator. He appeared visibly distressed, with profuse sweating and increased agitation. His blood pressure had also increased to 160/100 mm Hg and his heart rate was now at 120 bpm.

The nurse immediately communicated these changes to the attending physician. The physician ordered an arterial blood gas (ABG) analysis and a chest x-ray. The ABG results showed a pH of 7.28, PaCO2 of 55 mm Hg, PaO2 of 65 mm Hg, HCO3 of 24 mEq/L, and SaO2 of 85%. These values indicated the patient was experiencing acute respiratory acidosis, a complication often seen in patients with COPD who are on mechanical ventilation. The chest x-ray revealed increased opacities in the lower lobes of both lungs suggestive of a developing pneumonia. The physician suspected the patient might be developing ventilator-associated pneumonia, a common complication in ventilated patients.

Section 2

Change in Patient Status:

Later in the afternoon, the patient's condition continued to decline. His respiratory rate increased to 40 breaths per minute, and his oxygen saturation dropped to 79% despite having increased the ventilator settings. The patient appeared even more agitated, and his skin was cold and clammy to touch. His blood pressure had spiked to 180/105 mm Hg, and his heart rate was now at 130 bpm.

The nurse quickly alerted the physician to these developments, who then ordered a repeat arterial blood gas (ABG) and a complete blood count (CBC). The ABG results showed a worsening respiratory acidosis with a pH of 7.22, PaCO2 of 60 mm Hg, PaO2 of 60 mm Hg, HCO3 of 22 mEq/L, and SaO2 of 80%. The CBC revealed an elevated white blood cell count of 15,000 cells/mm3, indicative of an infection. The physician confirmed that the patient was indeed developing ventilator-associated pneumonia and ordered immediate antibiotic therapy. The patient’s worsening condition and the new findings necessitated a reassessment of the ventilator settings and a review of the patient's overall care plan.

Section 3

New Complications:

As the night progressed, the patient's condition further deteriorated. His oxygen saturation plummeted to 75%, and despite maximum ventilator support, the respiratory rate remained high at 45 breaths per minute. His pulse rate climbed to 140 bpm, and his blood pressure was now a concerning 200/110 mm Hg. The patient was in clear distress, with increasing agitation and visible perspiration.

The nurse swiftly called for a rapid response, and a STAT chest X-ray was ordered, which revealed a new, large infiltrate in the right lower lung, suggesting a developing pleural effusion. A blood culture was drawn, which would later confirm the presence of antibiotic-resistant Pseudomonas aeruginosa. Concurrently, the patient's blood glucose levels rose to 300 mg/dL, indicating stress hyperglycemia. The patient's deteriorating condition signaled a potential septic shock secondary to the ventilator-associated pneumonia, requiring immediate aggressive management and a thorough re-evaluation of the current treatment plan.

Section 4

Change in Patient Status:

Despite the aggressive management initiated in response to the suspected septic shock, the patient's condition continued to worsen. His oxygen saturation had not improved, lingering around 76%, and his respiratory rate remained high at 50 breaths per minute. The patient's pulse rate was now 155 bpm, further indicating his body's struggle. Although his blood pressure had slightly decreased to 190/105 mm Hg, it was still alarmingly high. The patient was also becoming increasingly lethargic, a stark contrast to his previous agitation.

The nurse noted new signs of peripheral edema and a decreased urine output, raising concerns about possible fluid overload and kidney dysfunction. The patient's Glasgow Coma Scale was now 9, down from 14 earlier in the shift, suggesting a significant decrease in the level of consciousness. His blood glucose levels continued to rise, now at 320 mg/dL, despite regular insulin administration. These new developments indicated a worsening systemic response to the infection and the patient's deteriorating overall condition. The healthcare team would need to reassess their approach, considering the potential for multi-organ dysfunction syndrome, and prepare for possible new complications.

Section 5

New Diagnostic Results:

The healthcare team decided to run a series of additional tests to evaluate the patient's deteriorating condition. An arterial blood gas (ABG) analysis was done, which revealed a pH of 7.29, PaCO2 of 50 mm Hg, and PaO2 of 55 mm Hg, suggesting the presence of respiratory acidosis. A repeat chest x-ray showed worsening bilateral infiltrates indicative of Acute Respiratory Distress Syndrome (ARDS). The patient's serum creatinine and blood urea nitrogen (BUN) levels had also risen to 2.5 mg/dL and 30 mg/dL respectively, suggesting possible acute kidney injury.

Furthermore, a Complete Blood Count (CBC) revealed a high white blood cell count of 20,000 cells/µL, reflecting an ongoing systemic infection. The patient's high lactate level of 4.0 mmol/L indicated ongoing tissue hypoperfusion. The healthcare team also noted an elevated brain natriuretic peptide (BNP) of 900 pg/mL, suggesting possible heart failure secondary to sepsis or volume overload. This new set of diagnostic results indicated the patient's progression towards multi-organ dysfunction syndrome and required the team to reassess their management strategy, considering the new and potentially fatal complications.