10 free Paramedic practice questions: Critical Care Concepts

Correct answer · The oxygen saturation of 99% on room air

Two very different problems land on the same three findings: fast breathing, clear lungs, and a low end-tidal carbon dioxide. A pulmonary embolism produces them because blood cannot reach ventilated alveoli, and that same blockage impairs gas exchange, so the saturation drops and responds poorly to oxygen. A metabolic acidosis produces them because the lungs are deliberately blowing off carbon dioxide to hold the pH up, and gas exchange itself is untouched, so the saturation stays normal. A saturation of 99% on room air is therefore the finding that does the sorting for you, and it points at the metabolic side.

Correct answer · The patient has lost effective circulation

Exhaled carbon dioxide has to be carried to the lungs by blood before it can be measured at the airway. When the ventilation has not changed and the waveform still has its normal rectangular shape, the machine is doing the same work it was doing a minute ago, so the missing piece is on the blood side. A drop from 38 mmHg to 9 mmHg over two breaths is a circulation that just failed: cardiac arrest, a massive clot, or profound shock. Check a pulse before you touch a single ventilator setting.

Correct answer · The ideal body weight calculated from height and sex

Lungs do not grow when a patient gains weight. Lung size tracks skeletal size, which is why the lung-protective tidal volume is calculated from ideal body weight, and ideal body weight comes from height and sex. Set it from the 140 kg on the scale and you can deliver a breath close to double what these lungs will hold, which overdistends alveoli and injures them with every cycle. Going too small is not safe either, since small breaths waste a larger share of each breath on dead space. You are aiming at a target, not just avoiding one side of it.

Correct answer · Lower the rate and lengthen the expiratory time

The disconnect already told you the diagnosis. Pressure that falls the moment the patient is allowed to finish exhaling is trapped gas, and trapped gas is what was choking off venous return and dropping the blood pressure. Reconnecting at the same rate rebuilds the trap within a minute. An obstructed airway empties slowly, so the fix is to give it time: slow the rate down and lengthen the expiratory phase. You will accept a higher carbon dioxide for it, which is a fair trade against a pressure that keeps collapsing.

Correct answer · Disconnect the ventilator and ventilate by hand with a BVM

Before you can fix anything you have to know whether the trouble belongs to the patient or to the machine, and one move answers that immediately. Take the patient off the ventilator and squeeze the bag yourself. If the chest is hard to inflate by hand too, the problem is in the patient: a displaced tube, an obstruction, or a pneumothorax. If the bag moves air easily, the ventilator or the circuit is at fault. It also strips away any contribution the settings were making while you work through displacement, obstruction, pneumothorax, and equipment in order.

Correct answer · Increase the rate to raise minute ventilation

Two levers run a ventilated patient, and they do different jobs. Rate and tidal volume clear carbon dioxide. Oxygen concentration and end-expiratory pressure fix oxygenation. A low pH sitting on top of a high PaCO₂ with an untouched bicarbonate is carbon dioxide the patient is not clearing, which is a ventilation problem, so you reach for the ventilation lever. Minute volume is tidal volume times rate, and with the volume already set for this patient's lungs, the rate of 10 is what you raise. Recheck the capnogram as you go and let the trend tell you whether it worked.

Correct answer · Increase the positive end-expiratory pressure

Work out which job is failing first. The carbon dioxide is 41 mmHg on a rectangular waveform, so ventilation is fine. The saturation is 86% on all the oxygen you have, so oxygenation is the failure, and flooded alveoli that collapse between breaths are why. End-expiratory pressure is the lever built for exactly that: it holds those units open so blood passing them actually picks up oxygen. The plateau of 22 cm H₂O is the permission slip, since it leaves room under the pressure ceiling that protects the lung. Raise the end-expiratory pressure in steps and watch the blood pressure, because that recruitment is bought with preload.

Correct answer · Rising airway resistance from an obstructed tube

These two pressures answer different questions, and the gap between them is the whole reading. Peak pressure is measured while gas is still moving, so it carries the cost of pushing air down a narrow pathway. Plateau pressure is measured after flow stops, when resistance no longer matters, so it reports how stiff the lung itself is. A peak that jumps while the plateau sits still means the pathway narrowed and the lung did not change: secretions, a kink, the patient biting the tube, or bronchospasm. Suction the tube and check it for kinking and biting before you touch a setting.

Correct answer · Continue suctioning and apply positive end-expiratory pressure

Gastric acid injures the alveolar lining within minutes, and the flooded alveoli stop taking part in gas exchange while blood keeps flowing past them. That is a shunt, and it is why the saturation stays low no matter how much oxygen you deliver. Management at this stage is mechanical. Clear what can physically be reached with suction, then apply end-expiratory pressure to hold the flooded and collapsing units open so blood passing them can pick up oxygen again. Both of those act on the actual problem, which is alveoli full of something other than air.

Correct answer · Give sedation and analgesia per protocol

Everything about the airway and the machine reads normal: a 98% saturation, a carbon dioxide of 38 mmHg on a clean rectangular waveform, equal breath sounds, and unchanged pressures. What changed is the patient. A paralytic has no sedative or analgesic effect at all, and the induction agent given twelve minutes ago has worn off while the long-acting paralytic has not. Tachycardia, hypertension, and tearing are the autonomic signs of a patient who is awake and aware and cannot move or tell you. Give scheduled sedation and analgesia, and keep giving them for as long as the paralysis lasts.