I wrote a piece a while back about the first lumbar puncture—LP in medical parlance—I ever did (or tried to do). A disaster beyond imagination. LP’s are always tough, even with a lot of practice, and I can’t remember any medical student being trusted to do one. But in my intern days in England, you learned, unsupervised, on the job.

An urbane 56-year-old (to my 25) doctor was my patient—in the peak of health until he woke up that Monday morning after a weekend’s gardening in excruciating back pain. The senior house officer insisted on an LP to exclude a multitude of rare and dread diseases; at the bottom of the pecking order, I lacked the chutzpah to question his authority, or to ask for help. Even fifty years on, it still comforts me to revisit this nightmare in my writing, the way PTSD counselors advocate reliving horribly traumatic past events from the safety of the present moment.

If you should ever feel disposed to perform an LP, you’ll get the how-to in exhaustive detail from several medical tomes. Just such a one I frantically consulted while my patient lay facing away from me on the gurney, legs scrunched up as far as possible towards his chin. Hard to picture a more excruciating posture for a chap with a slipped disc. As it later proved to be—a diagnosis for which an LP is actually contraindicated.

This morning I woke to a memory of my second LP. Equally challenging, but for a totally different reason. I was now interning on the oncology ward, and this time my patient was a 12-year-old American boy with leukemia, in London with his high-up diplomat dad who had some temporary business at the American Embassy. At least my nervy efforts proved successful, mercifully so in this sick, suffering and terrified teenager in an alien land. But this time, far from being completely normal, the test brought the worst news. His leukemia, in apparent remission following chemotherapy, had recurred. Which meant a lingering and painful death sentence in those days, as he was subjected to increasingly toxic and ineffective chemotherapy. Still at the bottom rung of the ladder, I was the one who had to administer this stuff at the behest of my boss.

Over the next forty years I had to do almost an LP every week—almost all on children. I got good at it, but I owe my success almost entirely to the expertise of my nursing colleagues. Expert not only in their skill at positioning these young ones in the exactly right position on the exam table. Then all I had  to do was squirt in local anesthetic and slip my needle between third and fourth vertebrae. Bingo (almost always), I was into the subarachnoid space and crystal-clear cerebrospinal fluid was dripping into my waiting test tube. But those nurses had a second even more crucial skill: that of consummate compassion in soothing even the most terrified toddler and calm matter-of-factness in conciliating the most rebellious adolescent.

I drilled into a generation of often questioning medical students: Never forget, nurses are not only your essential allies, they are your best teachers—if you allow them to be.