Air embolism may be fatal and can occur in conjunction with any entry into the vascular system at any time, but it commonly occurs at insertion and removal of central venous catheters (Bodenham et al. [43], Cook [86]). For air to enter the vascular system, a pressure gradient between the vascular space and atmospheric air must exist, giving a direct line of access to the blood vessel (Cook [86]). The severity of the embolism depends on:

Incidence is considered low and while the true frequency is unknown, it is estimated to fall between 1:47 and 1:3000 (Cook [86]). Prevention of air embolism requires careful insertion and removal techniques, adequate fixation, and safe handling when accessing the catheter (Bodenham et al. [43]). For prevention see Box 17.8. Presentations range from subtle neurological, respiratory or cardiovascular signs to shock, loss of consciousness and cardiac arrest (Bodenham et al. [43]). The most common signs and symptoms include sudden dyspnoea, light‐headedness, shoulder and chest pain, tachypnoea, tachycardia and hypotension (Cook [86]). Management includes turning the patient onto the left side and moving them into the Trendelenburg position. This is the optimal position as it decreases the gradient between the atmospheric air and the vessels and holds the entrapped air in the apex of the right atrium to prevent occlusion of the pulmonary artery (Cook [86]). The patient's vital signs should be monitored, and they should have 100% oxygen administered via a mask.

Pneumothorax is the presence of air in the pleural space between the lungs and the chest wall (Bodenham and Simcock [44], Scales [400]). It can occur for a number of reasons but is the most common complication with central venous catheterization. It results when a needle, guidewire, dilator or catheter inadvertently punctures the lungs during insertion of a central venous catheter. Incidence is 0.3–2.3%, and is highest using the subclavian route (Bodenham et al. [43]). It also depends on the experience of the operator, the site and the technique used (Biffi [33]). It is more common with the subclavian approach due to this vein's anatomical proximity to the lung. It is characterized by shortness of breath and sudden onset of chest pain but it may be clinically silent (Bodenham and Simcock [44], Bodenham et al. [43]) and only be discovered on the chest X‐ray performed following the procedure. It may be invisible on initial post‐procedure image and therefore staff and patients should be warned to report late signs and symptoms. Pneumothorax may also be diagnosed by ultrasound (Lichenstein et al. [269], Volpicelli [457]). Other symptoms include tachycardia, persistent cough and diaphoresis (Dougherty [123]).

Prevention is based on the skill level of the inserting practitioner (Biffi [33], Wigmore et al. [470]) as well as the use of ultrasound (Bodenham et al. [43], NICE [349]). If symptoms are noted during insertion, the practitioner should stop the procedure. The patient's colour, respirations and pulse should be monitored and oxygen should be administered. In the case of a small pneumothorax (up to 30% of the pleural cavity), the patient may be asymptomatic or feel slightly breathless but no intervention is required and the pneumothorax will heal spontaneously (Bodenham and Simcock [44], Bodenham et al. [43]). However, a large pneumothorax will necessitate the insertion of a chest drain (Biffi [33], Bodenham et al. [43], Scales [400]).

Haemorrhage results from damage to a vein and/or artery during or following insertion of a CVAD. It is not usually a serious problem unless the carotid artery is punctured (Bodenham and Simcock [44], Scales [400]). The incidence of arterial puncture is 0–15% (Qinming [378]). The use of ultrasound can help to reduce the risk of arterial puncture as the artery can be visualized during insertion (Bodenham and Simcock [44], Lamperti et al. [260], Qinming [378]).

The incidence of accidental arterial cannulation is estimated as 0.1–1% (Bodenham et al. [43]) and it can be recognized by excessive bleeding along the guidewire or on passing dilators and introducers. It is important to ensure that the patient is not compromised by having a high international normalized ratio (INR) or a low platelet count, or receiving anticoagulant therapy (Bodenham and Simcock [44]). These should all be corrected prior to CVAD insertion by administration of platelets and vitamin K, stopping medication a few days prior to insertion, or changing the patient from warfarin to subcutaneous injectable low‐molecular‐weight heparin, for example tinzaparin (Bodenham and Simcock [44], Dougherty [123]). If symptoms are noted at the time of insertion and the artery can be located, then digital pressure should be applied for at least 5 minutes (10 minutes if the patient has a bleeding disorder), or until haemostasis is achieved; the patient should then have 6 hours of bedrest if the procedure was an arterial cannulation (Bodenham et al. [43]). Pressure is not always possible as the ability to apply pressure depends on the location of the artery (Bodenham and Simcock [44], Qinming [378]). If symptoms are not recognized immediately then the patient may develop a mediastinal haematoma, which can then lead to tracheal compression and respiratory distress and require surgical intervention (Bodenham and Simcock [44], Bodenham et al. [43]).