A male client with a massive pulmonary embolus is tachycardic, hypotensive, and has audible bilateral pulmonary crackles. His arterial blood gas (ABG) results are: pH 7.0: PaCO, 66 mm Fig; HCO3- 24 mEq/L (24 mmol/L); PaO, 60 mm Hg. Based on these findings, this client is at greatest risk for which pathophysiological condition?

Reference Ranges:

pH [7.35 to 7.45] PaCO, [35 to 45 mm Hg]

HCO3- [21 to 28 mEq/L (21 to 28 mmol/L)]

PaO, [80 to 100 mm Hg]

The loop of Henle, a critical structure within the nephron of the kidney, plays a key role in the concentration of urine through the process of countercurrent multiplication. Here's why option D is the correct choice:

A) Calyx:

The calyx is a structure in the kidney that collects urine from the renal papillae and channels it into the renal pelvis. It does not directly participate in the concentration of urine.

B) Proximal convoluted tubule:

The proximal convoluted tubule primarily reabsorbs water, electrolytes, and nutrients from the glomerular filtrate, but it does not contribute significantly to the concentration of urine.

C) Renal pelvis:

The renal pelvis is a funnel-shaped structure that collects urine from the calyces and funnels it into the ureter. It is not directly involved in the concentration of urine.

D) The loop of Henle:

Correct. The loop of Henle is the nephron segment responsible for generating a hypertonic medullary interstitium, which creates the osmotic gradient necessary for urine concentration. The loop of Henle achieves this through countercurrent multiplication, where the descending limb allows passive reabsorption of water, while the ascending limb actively pumps out sodium and chloride ions. This creates an osmotic gradient that allows for further water reabsorption in the collecting ducts, leading to concentrated urine.

A) Nerve degeneration due to chronic gastric reflux:

Nerve degeneration due to chronic gastric reflux may lead to conditions such as gastroesophageal reflux disease (GERD) or esophagitis, but it is not directly related to the clinical presentation of intestinal obstruction. Symptoms of GERD or esophagitis typically include heartburn, regurgitation, and dysphagia rather than severe, colicky abdominal pain, nausea, vomiting, and abdominal distention.

B) Volvulus that occurred during an appendectomy:

Correct. Volvulus refers to the twisting of a segment of the intestine around its mesentery, leading to obstruction of the bowel lumen and compromising blood flow to the affected area. In this scenario, the client's clinical presentation of severe, colicky abdominal pain, nausea, vomiting, and abdominal distention is consistent with symptoms of intestinal obstruction, which can occur secondary to volvulus. Volvulus may result from various factors, including prior abdominal surgeries, such as an appendectomy, leading to abnormal positioning or adhesions within the abdomen.

C) Esophagitis due to reflux of gastric contents:

Esophagitis due to reflux of gastric contents can cause symptoms such as heartburn, chest pain, and difficulty swallowing, but it is not typically associated with severe, colicky abdominal pain, nausea, vomiting, and abdominal distention characteristic of intestinal obstruction.

D) A history of having Helicobacter pylori infection:

Helicobacter pylori infection is associated with conditions such as peptic ulcer disease and gastritis, but it is not directly related to the clinical presentation of intestinal obstruction. Symptoms of H. pylori infection may include abdominal pain, nausea, and vomiting, but they are not typically colicky and severe as those seen in intestinal obstruction.