Learn — X-rays, ECG strips & instruments (image-based)

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Surgical instruments — identification

Surgical instruments are the graded set of cutting, grasping, holding, retracting, clamping and suturing tools that the scrub nurse lays out, counts, passes and accounts for during an operation, each designed for one tissue and one job. Knowing them matters because the scrub nurse must anticipate the surgeon's next instrument rather than react to a request, must never hand a delicate instrument for heavy work, and shares legal accountability with the circulating nurse for the count that prevents a retained item.

Haemostats: mosquito forceps (fine, for small vessels), Spencer Wells and Kelly or Crile artery forceps all carry transverse serrations along the blade with a box joint and ratchet; Kocher's forceps add longitudinal serrations plus interlocking teeth at the tip and grip tough structures such as aponeurosis, thyroid tissue and the appendix stump — never bowel.
Tissue forceps: Allis holds tough tissue such as fascia or a skin edge, Babcock is fenestrated and atraumatic for hollow viscera (bowel, appendix, fallopian tube), Lane's is heavy, and among dissecting forceps the toothed (rat-tooth) pattern is for skin while the non-toothed is for bowel and vessels.
Scissors: Mayo scissors are heavy and cut fascia and sutures; Metzenbaum scissors are long-handled and fine for delicate dissection. Sutures are cut with the tips, and tissue scissors are never used on suture material or dressings because it blunts them.
Needle holders (Mayo-Hegar, Crile-Wood) grip the needle at the junction of the middle and rear thirds, and a curved needle is loaded so that its point faces the surgeon's thumb and is always passed with the point directed away from the receiving hand.
Retractors: hand-held Langenbeck, Morris, Deaver and Doyen (the last used for the bladder at caesarean section), and self-retaining Balfour, Bookwalter, Joll's for thyroid and the mastoid retractor for small wounds; hand-held retraction is released periodically so that pressure injury and traction on nerves are avoided.
Bowel and vascular clamps: crushing clamps such as Payr's and Kocher's go on the specimen side, non-crushing occlusion clamps such as Doyen's intestinal clamp, bulldog clips and the Satinsky side-biting clamp go on the side that is to be preserved, and a vascular clamp is closed only to the first ratchet.
Scalpels: a No. 3 handle takes blades 10, 11 and 15 (the 11 is the pointed stab blade for draining an abscess, the 15 for fine incisions) and a No. 4 handle takes the larger 20 to 24 blades; the blade is mounted and removed with a needle holder or blade remover and never with fingers, and the scalpel is transferred in a kidney tray or through a neutral zone rather than hand to hand.
Counting is a shared, spoken procedure: swabs, needles, blades and instruments are counted aloud by the scrub and circulating nurse together before the operation starts, when a body cavity is closed, at the start of skin closure and at the end, with the count recorded and any discrepancy stopping the closure. The WHO Surgical Safety Checklist frames this with sign-in, time-out and sign-out.
Reprocessing: instruments are kept moist after use, decontaminated and cleaned before sterilisation, jointed instruments are opened, and steam autoclaving runs at 121°C for 15 to 20 minutes at 15 psi or at 134°C for 3 to 4 minutes, with chemical indicators in every pack and biological or Bowie-Dick testing of the sterilizer as scheduled.

X-ray interpretation basics

Reading a radiograph is a fixed sequence rather than a glance: confirm the patient and the projection, judge the technical quality, then work through the film in the same order every time so that nothing is skipped. Five densities make the image — air is blackest, then fat, then soft tissue and water, then bone and calcium, then metal — and every abnormality is a change in one of them, which is why an air-filled bronchus only becomes a visible black line when the alveoli around it fill with fluid.

Check the identifiers before the anatomy: name, date, side marker and projection. A posteroanterior chest film is taken standing at full inspiration, while an anteroposterior portable film magnifies the heart and mediastinum, so cardiomegaly must never be called on a portable film.
Technical adequacy on a chest film: rotation is absent when the spinous processes lie midway between the medial ends of the clavicles, inspiration is adequate when 5 to 7 anterior or 8 to 10 posterior ribs are seen above the diaphragm, and penetration is correct when the vertebral bodies are just visible through the cardiac shadow.
The cardiothoracic ratio is the widest transverse cardiac diameter divided by the widest inner thoracic diameter on a posteroanterior film, and a ratio above 0.5 in an adult means cardiomegaly.
Left heart failure appears in a sequence — upper-lobe venous diversion, then peribronchial cuffing and Kerley B lines (short horizontal septal lines reaching the pleura at the bases), then bat's-wing perihilar alveolar shadowing, then pleural effusion; roughly 200 mL is needed before the costophrenic angle blunts on an erect film, while a lateral or decubitus view shows far less.
Consolidation with air bronchograms means the alveoli are filled, by pneumonia, oedema or haemorrhage, and the silhouette sign localises it: loss of the right heart border is right middle lobe, loss of the outline of the left hemidiaphragm is left lower lobe.
Post-primary pulmonary tuberculosis favours the upper zones with infiltrates and cavitation, primary disease shows hilar or paratracheal lymphadenopathy with a peripheral Ghon focus, and miliary tuberculosis gives uniform 1 to 3 mm nodules through both lungs; in a preterm neonate, low-volume lungs with diffuse ground-glass reticulogranular shadowing and air bronchograms is respiratory distress syndrome.
Free gas under the diaphragm on an erect chest film means perforation of a hollow viscus; the erect chest view is the most sensitive plain film for it, and a left lateral decubitus abdominal film is the substitute when the patient cannot sit up.
Tube and line positions are a nursing check on every film: the endotracheal tube tip 2 to 5 cm above the carina with the head neutral, the nasogastric tube tip below the left hemidiaphragm and clear of the bronchi, and a central venous catheter tip in the lower superior vena cava at the cavoatrial junction.
A chest radiograph delivers roughly 0.02 mSv, about three days of natural background radiation, but the ALARA principle still applies — ask every woman of childbearing age about pregnancy, shield where possible, and never repeat a film that has already answered the question.

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